FIELD
The present invention relates to a method of supplying a reducing gas containing
10 hydrogen to a shaft part of a blast furnace in an ironmaking plant aimed at cutting the amount of
C02 emitted from the ironmaking plant.
BACKGROUND
[0002]
15 As one measure for dealing with global warming, cutting the amount of C02 emitted
along with industrial production is being widely sought. As one part of this, to cut the C02
emitted in ironmaking operations using the blast furnace method, the art of manufacturing
hydrogen gas and supplying this to the shaft pa!1 of the blast furnace to thereby reduce the iron
ore by hydrogen and manufacture pig iron (that is, hydrogen smelting ofthe blast furnace) and
20 thereby cut the amount of use of coke and other carbonaceous materials jointly used as the
reducing material and fuel in the blast furnace (carbon input: amount of carbon charged when
producing I ton of pig iron) is disclosed in NPTLs 1 and 2. Here, the reason why hydrogen gas is
not supplied from the blast furnace tuyere, but from the shaft part is that the critical amount of
particulate coal able to be supplied is usually blown in ti·om the blast furnace tuyere. If in
25 addition to this supplying hydrogen gas from the tuyere, blast furnace operation efficient not
only in terms of spatial volume but also thermal terms would be difficult, so it is considered
advantageous to supply hydrogen from the shaft pa1i ofthe blast furnace where there is little
residual oxygen and there is leeway in thermal terms.
]0003]
30 As other prior art documents relating to the supply of gas to a blast furnace, PTLs I to 4
and NPTL 3 may be mentioned.
!0004]
PTL I describes the art of steam reforming gas containing tar and methane using a
catalyst so as to manufacture hydrogen.
35 !0005]
PTL 2 describes the art of blowing a reducing gas containing hydrogen into the shaft part
5
of a blast furnace during which adjusting the ratio of the amounts of iron ore and coke charged
into the blast furnace in the direction of the furnace diameter so as to obtain suitable reduction
and aeration inside the blast furnace.
[0006]
PTL 3 describes the art of supplying natural gas or gas obtained by pa1iial oxidation of
refined COG (coke oven gas) ti·om the shaft part of a blast furnace.
[0007]
PTL 4 describes the mi of supplying any of a nonrcducing gas obtained by causing
complete combustion of blast furnace gas etc. by air, a reducing gas obtained by indirectly
10 heating blast furnace gas etc., or a reducing gas with a high concentration of hydrogen of a
concentration of hydrogen of65% as a preheated gas to the shaft part of the blast fumace.
[0008]
NPTL 3 describes the result that even if supplying gas from the shaft part of a blast
furnace in an experiment using a blast furnace model, the supplied gas does not reach the center
15 part ofthe blast furnace.
[CITATION LIST]
[PATENT LITERATURE]
[0009]
20 [PTL I] Japanese Patent Publication No. 201 J-212552A
[PTL 2] Japanese Patent Publication No. 2013-185181A
[PTL 3] Japanese Patent Publication No. 37-8804B2
[PTL 4] Japanese Patent Publication No. 2009-22154 7 A
[NONPATENT LITERATURE]
25 [0010]
30
[NPL J] CAMPS-!S!J, vol. 23 (2010), pp. 1025
[NPL 2] CAMPS-!SIJ, vol. 25 (2012), pp. 886
[NPL 3] CAMPS-IS!J, vol. 23 (2010), pp. 879
[TECHNICAL PROBLEM]
[0011]
SUMMARY
As a tlrst problem of the prior mi, in the state of the art relating to the supply of hydrogen
gas to the shaft part of a blast furnace, there is the problem in particular of the unevenness of
35 distribution of the rate of reduction of iron ore by the hydrogen gas inside the blast furnace.
[0012]
2
This problem will be explained specifically,
[0013]
'fhc main iron ore reduction reaction inside a blast furnace is one where mainly CO gas
reduces the iron oxide (iron ore) to produce metal iron, This reaction is an exothermic reaction,
5 Fwiher, the amount of heal required for heating the iron ore or direct reduction of the iron ore by
carbon (endothennic reaction) is obtained by the latent heal of gas supplied from the tuyere
(tuyere supplied gas= air etc,) and the heat of combustion when causing the coke or coal inside
the blast furnace to burn by gas blown in from the tuyere (oxygen etc,) Further, the reduction of
iron oxide by hydrogen gas is an endothermic reaction, Therefore, supplying only hydrogen gas
10 tl,om the shaft part of a blast furnace with no tuyere supplied gas to perform all of the reduction
ofthe iron ore inside the blast furnace is impossible heat-wise, The amount of supply of
hydrogen gas from the shaft pa1i is limited to a value sufficiently smaller than the amount ofthe
tuyere supplied gas, If supplying such a small amount of hydrogen gas directly from the shaft
part of a blast furnace, as described in NPTL 3, the gas blown in rrom the shaft runs only near
15 the walls inside the blast turnace, The iron ore is reduced by hydrogen only in this region, lflhe
concentration of hydrogen gas becomes excessive near the tum ace walls, due to the hydrogen
reduction of the iron ore, the gas temperature will rapidly fall and the temperature required for
reduction will no longer be able to be maintained, so to maintain a suitable concentration of
hydrogen gas near the furnace walls, the possible amount of supply of hydrogen gas is only
20 allowed to be a value further smaller than the above upper limit Therefore, there is the problem
that due to the restriction on the amount of supply of hydrogen gas, it is not possible to set the
ratio of hydrogen reduction inside the blast furnace sufficiently high,
[0014]
Further, as a second problem of the prior art, there is the problem of the C02 emitted at
25 the time of manufacture of hydrogen, To supply a reducing gas containing the hydrogen
necessary for hydrogen smelting in a blast furnace inexpensively and in a large amount, it is
necessary to use hydrocarbons as the raw material for manufacturing it In the conventional
method for producing a reducing gas (hydrogen), there is the problem of C02 remaining in the
reducing gas and large amounts C02 being emitted along with combustion ofthe fuel for supply
30 of heat, so if totaling up the amount of C02 cut by the hydrogen smelting in the blast furnace and
the amount of C02 emitted at the time of manufacture of the reducing gas supplied to the blast
turnace, conversely the amount of emission of C02 increases and the hydrogen smelting
performed to cut the C02 does not worlc Such problems in hydrogen smelting conventionally
·were not recognized and no countermeasures vvcre taken.
35 10015]
Furthermore, as a third problem of the prior art, there is the problem of the constituents of
1 -'
- -----~~-,--
the reducing gas. Regarding the supply of the reducing gas to the shaft part of a blast furnace, in
the prior art, it was believed that it was sufficient to simply contain hydrogen in a high
concentration, but as a result of investigations by the inventors, it was learned that to actually
supply gas to a shaft of a blast furnace to smoothly continue hydrogen smelting inside the blast
5 fum ace and cut the C02 em i!ted by the blast furnace, there are severe restrictions on the
constituents of the reducing gas. In many prior mi, it has been proposed to supply a reducing gas
containing a large amount of a later explained unsuitable type of gas to the shaft part of a blast
furnace. With such a method, the operation becomes impossible for a short period of time or the
C02 emitted in the blast furnace cannot be cut.
I 0 [00l6]
The present invention, in consideration of the above situation, has as its object the
provision of a novel method for supplying a reducing gas to a shaft part of a blast furnace with
which it is possible to supply a large amount of reducing gas containing a high concentration of
hydrogen to a deeper position inside the blast furnace (location of blast furnace closer to center
15 axis in radial direction) and with which it is possible to cut the total amount of emission of C02
ofthe amount of C02 cut by the hydrogen smelting in the blast furnace and the amount of C02
emitted at the time of manulacture of the reducing gas and supplied to the blast furnace.
[SOLUTION TO PROBLEM]
20 [0017]
The gist of the method for supplying reducing gas to a shaft part of a blast furnace
according to the present invention is as follows:
( l) A method for supplying a hydrogen-containing reducing gas to a shaft part of a blast fumace,
the method comprising manufacturing a reducing gas by raising a temperature inside a reactor in
25 which an oxygen-containing gas is supplied to a preheated coke oven gas to 1200 to !800°C to
reform the coke oven gas and thereby produce reformed gas enriched in hydrogen gas, then
mixing the CO-containing gas with that reformed gas in the reactor to adjust the concentration of
hydrogen to 15 to 35 vol% (wet) and supplying the reducing gas to the shaft pa1i of the blast
furnace under a condition of a ratio of a tlow rate of blowing the reducing gas to the shaft pa!i I a
30 flow rate of blowing the reducing gas to the tuyerc > 0.42.
(2) The method tor supplying a reducing gas to a shaft part of a blast furnace according to the
above (I) wherein the oxygen-containing gas is oxygen gas and the method of reforming the gas
by raising the temperature in the reactor to 1200 to 1800°C is partial oxidation of the preheated
coke oven gas.
35 (3) The method for supplying reducing gas to a shaft part of a blast furnace according to the
above(!) wherein the oxygen-containing gas is steam produced by combustion of hydrocarbons
4
and the method of reforming the gas by raising the temperature in the reactor to 1200 to 1800°C
is mixing combustion gas of the hydrocarbons with the preheated coke oven gas.
[0018]
As more specific methods, for example, there are ones such as the following:
5 [1] The method according to the above (1) further comprising:
a) a step of raising the pressure of the coke oven gas,
b) a step of adjusting a flow rate of the coke oven gas,
c) a step of preheating the coke oven gas, and
d) a step of raising the temperature of the preheated coke oven gas inside the reactor in which
10 oxygen gas is supplied to 1200 to 1800°C and reforming the gas by pariial oxidation to produce
reformed gas enriched in hydrogen gas, then mixing into that reformed gas the CO-containing
gas in the reactor to adjust the concentration of hydrogen of the re!ormed gas to 15 to 35 vol%
(wet) and the temperature to 800 to l 000°C to produce refonning-use hydrogen gas for supply to
the shaft part of the blast furnace.
15 [2] The method according to the above [I] wherein a concentration of CO in the CO-containing
gas is 50 vol% to less than 99 vol% (dry), a concentration of C02 is 0 vol% (dry) to less than l
vol% (dry), a concentration ofH2 is 0 vol% (dry) to less than 35 vol% (dry), and a concentration
ofN2 is 1 vol% (dry) to less than 20 vol% (dry).
[3] The method according to the above[!] or (2] wherein the CO-containing gas is blast furnace
20 gas, con verier gas, or synthesis gas treated to remove C02.
[4] The method according to any one of the above[!] to [3] wherein the hydrogen-enriched
reformed gas contains a hydrocarbon gas in an amount of l% to 5%.
(5] The method according to any one oflhe above [1] to (4] wherein a flow rate of supply
(molls) of the oxygen gas is 0.4 to less than 0.5 time the flow rate of supply (molls) of carbon
25 atoms contained in the hydrocarbons in the coke oven gas.
[6] The method according to any one ofthe above [I] to [5] wherein as the coke oven gas,
reformed coke oven gas obtained by treating crude coke oven gas, obtained from a coke oven
provided with means for reducing a moisture in crude coke oven gas emitted, in a carbonization
furnace held at 700°C or more to break down the hydrocarbons in the crude coke oven gas is
30 used.
[7] The method according to any one of the above [I] to [6] wherein the step of raising the
pressure of the coke oven gas and the step of adjusting the flow rate of the coke oven gas are
perfonned in that order or in reverse order before the step of preheating the coke oven gas.
[8] The method according to the above (1) further comprising
35 a) a step of running coke oven gas ti·om the coke oven through a carbonization furnace and
breaking down the hydrocarbons in the coke oven gas into coke and hydrogen to thereby make
5
the concentration of hydrogen increase,
b) a step of removing the tar and at least part of the moisture in the gas run through the
carbonization furnace to manufacture a first reformed gas,
c) a step of raising the pressure of the first reformed gas,
S d) a step of preheating the raised pressure first reformed gas,
e) a step of supplying the preheated first refmmed gas to a patiial oxidation reforming apparatus
and supplying combustion gas to that partial oxidation reforming apparatus to fUJiher refmm the
hydrocarbons in the first reformed gas to make the concentration of hydrogen increase to
manufacture a second reformed gas, and
I 0 t) a step of supplying the second reformed gas !rom a gas supply port leading to the shaft part of
the blast furnace to the inside of the blast furnace.
[9] The method according to the above [8] fmiher comprising raising the pressure ofthe first
reformed gas to at least 0.2 MPa in pressure.
[!OJ The method according to the above [8] or [9] further comprising preheating the first
15 reformed gas to 800°C to I 000°C.
[11] The method according to any one ofthe above [8] to [!OJ fmiher comprising supplying
combustion gas to the partial oxidation refon:ning apparatus by
(i) supplying combustion gas obtained by supplying oxygen gas and flammable gas to a burner,
(ii) supplying oxygen gas and flammable gas to the pmiial refom1ing apparatus to generate
20 combustion gas inside that pmiial oxidation reforming apparatus and supplying the same, or
(iii) supplying oxygen gas to the inside of the partial oxidation reforming apparatus to make pmi
of the first reformed gas burn and supplying the same.
[12] The method according to any one of the above [8] to [II], fmiher comprising, before
preheating the tirst reformed gas, temporarily holding the raised pressure gas in a gas holder and
25 further raising the pressure of the gas from this gas holder.
[0019]
Next, characterizing features of the present invention will be explained.
[0020]
Characterizing Feature I of Present Invention
30 As described in the NPTL I, in the prior art, even if supplying reformed COG or other reducing
gas containing hydrogen in a high concentration to the shaft part of a blast furnace, the supplied
reducing gas ends up running only near the inside walls of the blast furnace. For this reason, the
supplied reducing gas can only reduce the iron ore near the inside walls of the blast furnace. In
this state, even if increasing the amount of supply of the reducing gas (flow rate of supply of
35 hydrogen gas), due to the effect of the increase in heat absorption at the time of reducing the iron
ore, it is not possible to maintain the temperature required for the reduction reaction inside the
6
blast furnace and there is the problem of the increase in the supplied hydrogen gas ending up
being exhausted tl·om the top of the blast surface without being used for hydrogen smelting. That
is, the upper limit of the flow rate of supply of hydrogen gas allowed in the prior art was low.
[0021]
5 Therefore, the present invention partially oxidizes COG containing a high concentration
ofhydrogen gas, mixes the high temperature pariially oxidized gas with blast furnace gas or
other CO-containing gas not containing almost any hydrogen gas and not high in temperature
(for example, 300°C or less) to suitably reduce the hydrogen gas concentration, then increases
the ratio of the flow rate of gas supplied to the shaft pari to the flow rate of gas supplied from the
10 tuyere (ratio of flow rate in blowing in reducing gas!flow rate in blowing reducing gas to tuyere)
to thereby cut the amount of heat absorption due to the reduction of iron ore ncar the inside walls
ofthe blast furnace and make the heat capacity oflhe supplied reducing gas increase to enable
hydrogen to reach a deeper part of the blast furnace close to the center part In particular, the
inventors discovered that by making the ratio of the flow rate in blowing in reducing gas/flow
15 rate in blowing reducing gas to the tuyere>0.42 and seHing the concentration of hydrogen gas in
the reducing gas to 15 to 35 vol% (wet), it is possible to increase the flow rate of the hydrogen
gas contained in the reducing gas supplied to the shaft part of a blast fumace compared with the
prior ali. As a result, in the presenfinvention, by making the ratio of hydrogen smelting in
reduction of iron ore in the blast furnace increase, it is possible to cut the C02 exhausted from
20 the blast furnace.
10022]
Characterizing Feature 2 of Present Invention
The inventors learned, as a result of their investigations, that there are the following restrictions
on the constituents sought from the reducing gas supplied to the shaft part of a blast furnace for
25 hydrogen smelting use.
[0023]
A first restriction is that the methane and other hydrocarbons have to be 2.5 vol% or less.
This is because at the temperature at the shaft part of a blast furnace, part of such hydrocarbons
will decompose by heat and produce solid carbon (coke). If the concentration of the supply of
30 hydrocarbons is excessive, coke will deposit in the spaces between material charged into the
blast furnace and clog the channels giving rise to the problem of difficult continuation of blast
furnace operation.
[0024]
A second restriction is that almost no C02 must be contained. This is because most of the
35 C02 supplied to the shaft pmi of a blast furnace is exhausted as is from the top of the blast
furnace without being used for a reaction inside the blast furnace whereby the amount of C02
7
exhausted tl·om the blast furnace is made to directly increase.
]0025]
A third restriction is that it is necessary that the concentration of steam be sufficiently
small (tor example, 10 vol% or less). This is because, in the shaft pati of a blast furnace, steam is
5 a substance which can oxidize the CO inside the blast furnace and emit C02 and the majority of
it is not used tor any reaction inside the blast furnace, so if supplying it in an excessively high
10
15
20
concentration, the concentration of the reducing substance in the reducing gas (H2 or CO) is
lowered and the speed of the reduction reaction of the iron ore in the blast furnace is lowered.
[0026]
Similarly, from the viewpoint of not causing a drop in concentration of the reducing
substance in the reducing gas, the concentration of nitrogen gas or other substances not reacting
much at all in the shaft part of a blast furnace becoming excessively high (for example, 20% or
more) must also be avoided.
!0027]
In the prior art, for example, it has been proposed to directly supply COG to the shaft pati
of a blast furnace, but COG usually contains about 30% of methane gas, so due to the above first
restriction, such a gas is not a constituent suitable as a reducing gas to be supplied to the shaft
part of a blast furnace.
[00281
Further, if using gas obtained by steam reforming natural gas or COG as the reducing
gas, addition of a large amount of steam would be unavoidable (or in a usual coke oven, crude
COG inherently contains a large amount of 10% or more of steam), so the reformed gas would
contain for example a large amount of 20% or more of C02 and 50% or more of steam. Such a
gas is not suitable in view ofthe above second and third restrictions.
25 [0029]
Furthermore, in the prior art of adding oxygen to a raw material of naphtha or natural gas
or other hydrocarbons at ordinary temperature or preheated to a relatively low temperature (for
example 300°C) and supplying the partially oxidized gas to the shaft part of a blast furnace as
well, the general practice is to simultaneously add steam to promote the refom1ation ofthe
30 hydrocarbons, so this is not suitable due to above third restriction. Even if not using steam, it is
necessary to add a large amount of oxygen gas (for example 02/C~0.7) so as to raise the
temperature ofthe raw material gas to a temperature sufficient for oxidation. In this regard, in
such a partial oxidation reaction of hydrocarbons, not including hydrocarbons but including only
CO as an oxide is the ideal operating condition ll·om the viewpoint ofthe above restrictive
35 conditions on the constituents. The specific condition is 02/C~O.S. In the above prior art, the
partial oxidation reaction becomes one under the condition of excess oxygen (that is, 02/C>O.S),
8
so at the time of partial oxidation, several %to I 0% or more of C02 is generated, so this is not
suitable from the above second or third restriction, In the prior art, to cut the C02 emitted in the
partial oxidation, setting the reaction temperature higher and operating in a temperature region
where C02 cannot be emitted in an equilibrium state is aimed at I Jowcver, for this, in the past,
5 the method of increasing the amount of supply of 02 to make the amount of temperature rise
increase was employed, so the amount of supply of02 became fmiher excessive. As a result, the
excessive oxygen formed not C02, but formed H20 resulting in emission of a large amount of
H20, so 02 is not a suitable constituent from the above third restriction.
10
[0030]
ln the present invention, COG is patiially oxidized to cut the hydrocarbons in the COG.
At that time, to suppress the emission of C02 and H20, 02/C is cut more than in the prior art. ln
particular, by performing partial oxidation under conditions of less oxygen than the above ideal
02/C ratio (0.5), it is possible to avoid the emission of C02. Under such partial oxidation
conditions, the amount of02 added is relatively small, so the amount of temperature rise due to
15 the heat ofthe partial oxidation reaction is smaller than the prior art, the temperature able to be
reached after partial oxidation becomes lower than the prior art, and the hydrocarbons in the
COG cannot be completely broken down. However, in the present invention, the inventors
discovered that the above first to third restrictions can be satisfied by operation under conditions
combining the conditions of making the 02/C a ratio of 0.4 to less than 0.5, making the
20 preheating temperature oft he COG a much higher one than the prior art of 800 to l 000°C, not
adding steam at the time of partial oxidation, mixing the high temperature gas obtained by partial
oxidation of COG with non-high temperature CO-containing gas, and more preferably using
reformed COG obtained by decomposing and reforming by a carbonization fumace the high
temperature crude COG exhausted as COG from a coke oven provided with means for reducing
25 the moisture.
[0031]
At the partial oxidation reaction temperature or more, by making the 02/C ratio in the
partial oxidation 0.4 to less than 0.5, it is possible to break down about 80% or more of the
hydrocarbons initially contained in the COG. Further, by using the above reformed COG, the
30 concentration of hydrocarbons in the initial COG is diluted by the H2 or CO gas emitted by the
decomposition and reforming operation and it is possible to greatly reduce the concentration of
hydrocarbons in the raw material gas ofthe partial oxidation. Furthermore, by not adding steam
at the time of partial oxidation, it is possible to avoid inclusion of excessive H20 in the reducing
gas. By mixing the high temperature gas obtained by partial oxidation of the thus obtained COG
35 with the non-high temperature CO-containing gas, it is possible to greatly reduce the
concentration of hydrocarbons remaining in the partially oxidized gas. Regarding the point of
9
insufficient amount of temperature rise due to the beat of partial oxidation reaction, the minimum
extent of preheating is performed so as to obtain the lower limit temperature under conditions
where the reforming reaction temperature can be maintained during the steam reforming reaction
(endothermic reaction) where the peak temperature at the time ofthc partial oxidation can
S continue after the partial oxidation. The inventors discovered, as a result of their investigations,
that preheating at 800 to I 000°C under the above 02/C condition is suitable.
[0032]
According to the present invention, by minimizing the C02 and H20 used as the
reducing gases supplied to the shaft part of a blast furnace by rendering the 02/C ratio a region
I 0 where the oxygen is stoichiometrically insufficient (!hat is, 02/COA2, As the reducing gas supplied to the shaft part, it is preferable to usc gas obtained by
heat treating coke oven gas to reform it and manufacture low CO concentration and high H2
concentration gas and diluting it to adjust the concentration of hydrogen,
10
[0042]
Here, the process performed by the inventors in perfecting the present invention will be
explained in brief
[0043]
The hydrogen-containing reducing gas adjusted to a temperature suitable as a reducing
gas to be supplied to the shaft part of a blast furnace (in the following explanation, sometimes
15 simply referTed to as the "reducing gas") is supplied to the shaft part of a blast fumace (part
configured by providing plurality of through holes around shaft of blast furnace and supplying
reducing gas there), For the structure and materials of the shaft part of a blast furnace, ones of the
prior art can be applied,
20
(00441
I) Constituents of Reducing Gas and Method of Calculating Temperature
Reforming Reaction
The reforming reaction predicated upon for obtaining the reducing gas used in the present
invention is as follows if taking the example of methane as the hydrocarbons of the raw material:
Steam reforming reaction: CH4 (hydrocarbon)+H20 -7 3 1-b+CO (fom1ula 1)
25 Heat decomposition reforming reaction: CH4 (hydrocarbon) -7 C (solid carbon)+2 H2 (formula
2)
Pariial oxidation reforming reaction: CH4 (hydrocarbon)+O,S 02 -7 2 H2+CO (formula 3)
Further, if using coke oven gas as the raw material, the partial oxidation reaction of formula 3 is
generally made a general reaction in which the reaction of the formula 1 continues after the
30 followiug reaction:
Combustion of hydrogen gas: H2+0,S 02-7 H20 (formula 4)
In addition to this, as the main reaction in which hydrogen gas is increased and decreased, there
is the following:
Aqueous shift reaction: CO+H20 -7 H2+C02 (formula 5)
35 [0045]
The solid carbon generated in the heat decomposition reforming reaction is mainly coke,
13
5
This contains some hydrogen in addition to carbon, so the right side of the heat decomposition
reforming reaction strictly speaking is "CnHm (solid carbon)", but in general, n>m, so tor
simplification of the explanation, the expression of formula 2 is used.
[0046]
Composition of Reformed Gas at Time of Partial Oxidation Reforming Reaction
The gas can be sampled at an exit side ofthe pm1ial oxidation apparatus and its composition
found using gas chromatography etc. Here, the hydrocarbon (for example, methane)
decomposition rate is defined as the ratio of!he volume flow rate of the hydrocarb'ons contained
in the gas after partial oxidation (converted to standard state) to the volume flow rate of
I 0 hydrocarbons contained in the raw material gas ( converied to standard state). For example,
"methane decomposition rate 70%" means 30% of the methane present in the raw material gas
remains in the reformed gas.
[00471
It is known that the constituents of the gas obtained by a patiial oxidation refonning
15 reaction or steam reforming reaction (no catalyst) of hydrocarbons under conditions greatly
exceeding l 000°C are close to the equilibrium composition of the reaction end temperature
(substantially reactor exit side temperature) if providing a sufficient residence time of!he gas in
the reactor. Therefore, by calculating the equilibrium constituents, it is possible to evaluate the
reforming perfonnance of the partial oxidation reaction and steam refonning reaction (no
20 catalyst) under conditions greatly exceeding I 000°C. Further, a thennocouple or other
thermometer is provided inside the partial oxidation apparatus to measure the peak temperature.
[0048]
2) Method of Evaluation of Effect of Blowing Reducing Gas into Shaft of Blast Furnace
A test was run blowing hydrogen gas into the blast furnace shaft of a lest blast furnace, To
25 reproduce the results, a numerical simulation of the flow of gas inside the blast furnace was
perfonned. This simulation was used to calculate and evaluate the flow of gas inside the blast
fumace under various blowing conditions.
[0049]
Method of Simulation
30 Numerical simulation was performed simulating the dimensions and shape of a lest blast furnace.
This is a technique of direct solution by setting discrete equations of motion and equation of
energy of a fluid. With this technique, it is possible to individually set the conditions for supply
of gas to the blast furnace tuyere and the conditions for supply of gas to the shaft part of a blast
fumace. At the lest blast furnace, as described in PTL 2, the phenomenon of the gas blown into
35 the shaft part rising only near the furnace walls was confirmed. To reproduce this tlow, various
parameters were adjusted to secure the precision of the numerical simulation.
14
- - - -- ---- ----:--:; -------- '
10050]
The flow rate of hydrogen gas for supply to the shaft part/tlow rate of gas for supply to
the tuyere was simulated under various conditions and the depth in the blast furnace reached by
the hydrogen gas supplied to the shaft pa!i and the distribution of concentration of the hydrogen
5 gas supplied to the shaft part in a blast furnace were found.
10051]
3) Behavior of Reducing Gas Inside Blast Furnace
The upper limit of the flow rate of H2-containing gas (reformed COG etc.) blown into the shaft
paii in the test blast furnace is defined by the amount of drop of local temperature accompanying
10 reduction (endothermic reaction) at a certain location inside the blast furnace (near furnace
walls) due to H2 reduction. If blowing gas by more than the upper limit of the inflowing flow
rate (flow rate of gas blown into shaft), the concentration ofH2 at a certain location will become
excessive and a temperature enabling reduction will no longer be able to maintained there, so H2
reduction will slop and the effect of reduction ofthe carbon input (effect of reduction of amount
15 of carbon input when producing l ton of pig iron -this being an important factor in measures
against global warming) will no longer be improved. Further, at this lime, the majority of the 112
supplied to the shaft part is wastefully discharged from the top of the blast furnace without
patiicipating in any reaction. In the tests at the test blast fumacc, in tests where the effect of
reduction of the carbon input could be sufficiently observed due to the effect of hydrogen
20 reduction inside the blast furnace, it is conceivable that the concentration of H2 at a certain
location was not excessive, so the concentration of H2 at a certain location in conditions resulting
in the maximum flow rate of gas blown into the shaft of a blast furnace among such test
conditions can be defined as the upper limit value ofthe concentration of H2 at the shaft part at a
cet1ain location. Measurement inside the blast furnace is difficult, so the upper limit of
25 concentration ofH2 cannot be directly measured, so the average concentration ofH2 in a
predetermined region near the furnace walls of a region where the H2 gas in the reducing gas
supplied from the shaft part passes when supplying reducing gas for supply to the shaft pat1 to
the shaft part of a blast furnace is calculated from the results of a numerical simulation of the
flow inside the blast furnace reproducing the test under the maximum condition oflhe in flowing
30 flow rate. The value of this average concentration ofH2 can be made the upper limit value of the
concentration ofH2 at the shaft part. As the predetermined region for obtaining an average of the
concentration of H2 near the furnace walls, for example, outside by 95% of the inside diameter
of the blast furnace is possible. As a result of running the above simulation based on the test
results in the test blast furnace, it was discovered that the upper limit value of the concentration
35 of H2 at the shaft part is 35%. The concentration of H2 in the in flowing gas (concentration of
intlowing H2) can change in various ways due to differences in the raw material gas etc., but as
15
----- -- ------,-~-;-:
an indicator for maintaining a good H2 reduction reaction in a blast furnace, as explained above,
it was learned that it is suftlcient to set the operating conditions so that the upper limit
concentration of H2 at the shaft part becomes 35% or less. That is, if the upper limit value of the
concentration of H2 at the shaft part or less inside the blast furnace, it can be judged that the
5 endothermic reaction at the time of hydrogen reduction is not excessive and that hydrogen
reduction is proceeding well at that location.
[0052]
The concentration of reducing gas inside the blast furnace when making the flow rate of
hydrogen gas (reducing gas) for supply to the shaft part of the blast turn ace increase more can be
I 0 found by a similar numerical simulation. If using the calculated value ofthe concentration of
reducing gas in this region near the furnace walls so as to set the concentration of H2 in the
reducing gas so that the average concentration of H2 at the above region near the furnace walls
(attime corresponding to flow rate of reducing gas supplied at the test blast furnace) becomes
not more than the upper limit value of the concentration of H2 at the shaft part, hydrogen
15 reduction in the blast furnace becomes possible (this is because at the deeper part of the blast
fumace, the concentration of H2 falls from that at the region near the furnace walls, so the effect
of the endothennic reaction at the time of hydrogen reduction becomes smaller), At this time, the
upper limit value of the flow rate of supply of H2 in the reducing gas to the shaft part of the blast
furnace can be found by
20 [Upper limit value of concentration ofH2 in reducing gas (upper limit value of concentration of
in flowing H2)]x[Flow rate of supply of reducing gas (in flowing gas)],
!0053]
Even if the allowed concentration of H2 at the shaft part is constant, the upper limit value
of the concentration ofinflowing H2 will change depending on the flow rate ofthe reducing gas.
25 The relationship of the upper limit value of the concentration of in flowing H2 (upper limit value
of concentration ofH2 in reducing gas) to the ratio of flow rates of blowing operations(= [flow
rate of gas flowing in (blown into shaft)]/[flow rate of gas blown into tuyere]) will be explained
using FIG. I. In the figure, the black dot is the test point, in the test of supplying refonned COG
independently to the shaft part in the test blast furnace, showing the concentration ofinflowing
30 H2 of the upper limit possible under the condition ofthe maximum flow rate of blowing gas to
the shaft (in the figure, the "UPPER LIMIT VALUE OF RATIO OF FLOW RATES OF
BLOWING OPERA T!ONS WITH REFORMED COG ALONE"). In the figure, the curve of the
upper limit value of the concentration ofinflowing H2 passes through this test point. The
supplied hydrogen gas (reducing gas) blown into the blast furnace from the shaft part is quickly
35 mixed with the rising tlow derived from the gas blown in from the tuyere in the region near the
walls ofthe blast furnace resulting in the concentration ofH2 falling compared with that in the
16
- ------ -------,-~,
inilowing gas. In general, if rnaking the flow rate of reducing gas containing H2 blown in from
the shaft part (tlow rate ofinf1owing gas) increase, this effect of mixing is reduced and the
concentration ofH2 near the wall surfaces increases. For this reason, to obtain the allowed
concentration of H2 at the shaft part or less, it is necessary to further decrease the concentration
5 ofH2 in the inflowing gas. The upper limit value of the concentration ofinflowing H2 falls. For
this reason, if supplying to the shaft pa1i just pa.tially oxidized or otherwise reformed gas of
reformed COG or refined COG, in which the value of the concentration ofH2 is substantially
fixed, it is not possible to make the flow rate of inflowing gas increase to at least the condition at
the test blast furnace. To make the flow rate of in flowing gas increase more than this, it is
l 0 necessary to dilute the reformed gas to lower the concentration of H2 in the inflowing gas. In
FIG. I, the upper limit value of the concentration ofintlowing H2 falls along with the increase in
the flow rate of gas blown into the shaft part (increase in ratio of flow rates of blowing
operations) and gradually approaches the upper limit value of the concentration oHll at the shaft
prui (35%). This gradually approached value (35%) of the upper limit value of the concentration
15 of in flowing H2 will be called the "critical upper limit value of the concentration of inflowing
lb". lfthe ratio of flow rates of blowing operations is particularly large, the reducing gas near
the tumace walls of the blast furnace will not be diluted much at all by the gas blown into the
tuyere, so the upper limit value of the concentration ofH2 at the shaft part will become the upper
limit value ofthe concentration ofinflowing H2 as it is (critical upper limit value of
20 concentration ofinflowing H2), Fmiher, if there are special circumstances such as convenience
in work, the concentration of H2 in the inflowing gas may be made a concentration of less than
the upper limit value.
10054]
As shown in FIG, 2, the ratio of flow rates of blowing operations is made to increase to
25 thereby make the cross-sectional area of passage in the blast tum ace of intlowing gas supplied
from the shaft increase more. That is, it is possible to make the reducing gas reach a deeper
location inside the blast fumace (closer to center axis of blast furnace). However, there are
restrictions in blast furnace operations on the ratio of flow rates of blowing operations, If
blowing in reducing gas from the shaft part, trom the viewpoint of uniformity of the hydrogen
30 reduction reaction inside the blast furnace, the cross-sectional area of passage ofthe reducing gas
(horizontal plane) is preferably at least 50% ofthe cross-sectional area ofthe blast furnace
(horizontal plane) (see FIG. 2, "LOWER LIMIT VALUE OF RA T!O OF FLOW RATES OF
BLOWING OPERATIONS PREFERABLE IN BLAST FURNACE OPERATION"). In fact,
even with a ratio of flow rates of blowing operations below this such as in a test blast tumace,
35 operation of the blast tl1rnace is not impossible, but if the hydrogen reduction region remains at a
cc1tain location near the furnace walls, the difference in temperature distribution in the furnace
17
will increase. This is not preferable from the viewpoint of the stability of operations. The crosssectional
area of passage of the intlowing gas is found from the results oflhe above-mentioned
numerical simulation and was de lined as !he region of concentration of intlowing gas of I 0% or
more at !he lop end ofthe material charged into the blast furnace. On the other hand, trom the
5 viewpoint of operation stability, the ratio of the tlow rate of in flowing gas from the shaft part and
the flow rate of gas blown into the tuyere (ratio of flow rates of blowing operations) has to be I
or less (see "UPPER LIMIT VALUE OF RATIO OF FLOW RATES OF BLOWING
OPERATIONS DUE TO RESTRICTIONS ON BLAST FURNACE OPERA T!ON" in FIG. 2).
This is because if a ratio of flow rates of blowing operations greater than this, the amount of heat
I 0 supplied due to the gas supplied ti-orn the tuyere becomes insufficient and !he blast furnace
operation becomes unstable. Therefore, the region in FIG. 2 between the "LOWER LIMIT
VALUE OF RA T!O OF FLOW RATES OF BLOWING OPERATIONS PREFERABLE IN
BLAST FURNACE OPERATION" and the "UPPER LIMIT VALUE OF RATIO OF FLOW
RATES OF BLOWING OPERATIONS DUE TO RESTRICTIONS ON BLAST FURNACE
15 OPERA T!ON" is the range of ratio of flow rates of blowing operations suitable in blast furnace
operation. Further, the "UPPER LIMIT VALUE OF RA TlO OF FLOW RATES OF BLOWING
OPERA TlONS WITH REFORMED COG ALONE" in FIG. 2 shows the upper limit value of the
flow rate ofinflowing gas in the p1'ior art (results of test blowing reforn1ed COG into shaft part
oflest blast furnace- corresponding to lest point in FIG. 1) and is not necessarily a suitable
20 condition in blast furnace operation.
[0055]
Furthermore, in terms of the object of the present invention, it is advantageous to increase
the flow rate of H2 supplied to the shaft part of a blast furnace. From this viewpoint, there is a
further restrictive condition on the concentration of inflowing H2. This restrictive condition will
25 be explained using FIG. 3. Along with increasing the ratio of flow rates of blowing operations
(ratio of flow rate of gas flowing in from shaft part and flow rate of gas blown in from tuyere ),
the flow rate ofH2 able to he supplied from the shaft part to the inside of the blast furnace
together with the inilowing gas (upper limit value of flow rate of in flowing H2) increases (see
curve of"TIME OF UPPER LIMIT OF CONCENTRA T!ON OF INFLOWING Hi' in FIG. 3).
30 However, when increasing the tlow rate of in !lowing gas from the intlowing gas conditions of
the reformed gas containing a high concentration ofH2 (reformed COG or COG partial oxidation
reformed gas etc.) alone, as shown in FIG. I, near the "UPPER LIMIT VALUE OF RATIO OF
FLOW RATES OF BLOWING OPERA TlONS WlTH REFORMED COG ALONE", the
allowed upper limit value of the concentration of the in flowing H2 rapidly falls cancelling out
35 the majority of the effect of increase ofthe upper limit oflhe tlow rate ofthe in!1owing H2 due to
the increase in flow rate ofthe in!1owing gas, so ncar the "UPPER LIMIT VALUE OF RATIO
18
----------------- ~T
OF FLOW RATES OF BLOWING OPERA T!ONS WITH REFORMED COG ALONE"', even
if increasing the ratio of tlows rates of blowing operations, the increase ofthe upper limit of the
tlow rate ofthe inflowing I-12 is kept at a slight effect. Furiher. the area near the "UPPER LIMIT
VALUE OF RATIO OF FLOW RATES OF BLOWING OPERATIONS WITH REFORMED
5 COG ALONE" is less than the "LOWER LIMIT VALUE OF RATIO OF FLOW RATES OF
BLOWING OPERATIONS PREFERABLE !N BLAST FURNACE OPERATIONS" shown in
FIG. 2 and is not a suitable range of operating conditions. In this way, near the "UPPER LIMIT
VALUE OF RATIO OF FLOW RATES OF BLOWING OPERATIONS WITH REFORMED
COG ALONE", a concentration of inflowing 1-12 of a high concentration of I-12 (value far
10 exceeding critical upper limit value of concentration of intlowing I-12 (35% )) is possible, but
operation in this region is not preferable. On the other hand, as explained above, if a
concentration ofinflowing I-12 of not more than the 35% ofthe critical upper limit value of
concentration ofintlowing 112, this can be applied without impeding the blast fumace operation
in the above "RANGE OF RATIO OF FLOW RATES OF BLOWING OPERATIONS
15 SUITABLE IN BLAST FURNACE OPERATION"'. When making the critical upper limit value
ofthe concentration ofinflowing I-12 (35%) the concentration ofinflowing l-12 ("TIME OF 35%
CONCENTRATION OF !NFLOWING H2" in figure), the flow rate ofinflowing H2 in the
majority ofthe region ofthe "RANGE OF RATIO OF FLOW RATES OF BLOWING
OPERATIONS SUIT ABLE IN BLAST FURNACE OPERATION" in the figure matches the
20 tlow rate of in flowing I-12 at the "TIME OF UPPER LIMIT OF CONCENTRATION OF
INFLOWING Hi' in the figure and becomes the maximum flow rate ofinflowing I-12. A flow
rate of inflowing I-12 greater than that of the prior art can be realized. For example, in the case of
a concentration ofinflowing I-12 of35% and a ratio oftlow rates of blowing operations of 1.0, a
flow rate of inflowing I-12 of2 times or more the prior art is possible. In a region where the ratio
25 of flow rates of blowing operations falls greatly below 0.5, the flow rate ofinflowing I-12 at a
concentration of inflowing I-12 of 35% becomes a smaller value than that of the prior art, but
operation under the condition of such a small ratio of flow rates of blowing operations is not
preferable in blast furnace operation, so basically this cannot be employed. Therefore, as the
upper limit value ofthc concentration of in flowing H2, about 35% is preferable.
30 [0056]
A concentration of inflowing I-12 of less than 35% can also be employed, but to make the
flow rate of in flowing H2 increase, the concentration of inflowing I-12 has to be one where the
flow rate of in flowing H2 can become larger than the past. From FIG. 3, when the concentration
of inflowing I-12 is ]5°/,,, a flow rate of in flowing 1-b equal to the upper limit value of the ilow
35 rate ofintlowing l-12 in the prior arl at the upper limit value (1.0) ofthe ratio oft1ow rates of
blowing operations can be realized, For this reason, if a concentration of in flowing I-12 less than
19
5
- - ---- ---- ----_,-
1 5%, a tlow rate of inilowing H2 exceeding the upper lim it value of the prior art cannot be
realized, so this is not suitable. Therefore, as the lower limit value ofthe concentration of
in flowing H2, 15% is preferable.
[0057]
If considering the object ofthe present invention of obtaining a flow rate of in flowing H2
above the upper limit value ofthe flow rate of in flowing H2 in the prior art in addition to the
above restrictive condition on the concentration of inilowing H2, as a more preferable operating
condition, the "SUITABLE OPERATING RANGE" shown by the hatching in FIG. 3 can be set.
The upper limit value ofthe concentration of inflowing H2 satisfying this "SUITABLE
l 0 OPERATING RANGE", as explained above, is the upper limit value of the concentration of
in flowing lb or a value close to this, that is, 35%.
[0058]
This "SUITABLE OPERATING RANGE" corresponds to the range where the
concentration of H2 which can be blown into the shaft part can be made to increase. It is leamed
15 that to realize this range, the ratio of the tlow rate of shaft blowing/flow rate oftuyere blowing
has to be made at least the value at the cross point of the line of the flow rate ofintlowing
H2/upper limit value of flow rate of in flowing H2 = 1.0 and the curve of a concentration of
inflowing H2 of35% in FIG. 3. The ratio of the flow rate of shaft blowing/tlowrate oftuyere
blowing at this cross point is about 0.42. That is, the present invention able to supply H2 in a
20 larger amount to deeper in the blast furnace can be realized under this condition of the ratio of
the flow rate of shaft blowing/tlow rate oftuyere blowing.
[0059]
Further, the lower limit value of the concentration ofinilowing H2 satisfying the
"SUITABLE OPERATING RANGE" can be expressed by the following fonnula:
25 [Lower limit value of concentration of inflowing H2] =[Upper limit value of flow rate of
inilowing H2 in prior art (blowing only COG into shaft)]/[Fiow rate ofinflowing gas]
[0060]
Further, increasing the ratio of flow rates of blowing operations also has the effect of
improving the spatial unifmmity of the H2 reduction reaction in the blast furnace such as shown
30 in FIG. 2, so from the viewpoint of stress on such reaction uniformity, it is also possible to
employ operating conditions resulting in a somewhat lower flow rate ofinilowing H2 than the
upper limit value of flow rate ofinflowing H2 in the prior art so long as within the "RANGE OF
RATIO OF FLOW RATES OF BLOWING OPERATIONS SUITABLE IN BLAST FURNACE
OPERATION".
35 [0061]
Further, in the present invention, gas obtained by diluting by the blast furnace gas the low
20
CO concentration and high H2 concentration gas manufactured from the coke oven gas is used as
the reducing gas, so the inflowing gas unavoidably contains steam. The steam in the reducing gas
acts to reduce the concentration ofH2 and acts to enable the reducing gas to reach a deeper part
of the blast fumace. Regarding this, it has a similar effect as the blast furnace gas for dilution use
5 in the present invention, so the concentration ofinflowing H2 should be defined by the wet%
including steam.
10062]
Next, the reducing gas for supply to the shaft part will be explained. As explained
previously, the reducing gas for supply to the shaft pa11 has to have a hydrogen concentration of
10 15 to 35 vol% (wet). The reducing gas should be supplied to the shaft part at 800 to I 000°C in
temperature so that the operation of the blast furnace is not impeded further.
[0063!
As the reducing gas satisfying such a condition, it is not possible to directly utilize the
coke oven gas or blast furnace gas usually emitted in an ironmaking plant. Therefore, in the
15 present invention, low CO concentration and H2 concentration gas manufactured from coke oven
gas is diluted by blast furnace gas to adjust the hydrogen concentration for use of the gas.
[0064]
For example, the reducing gas used in the present invention can be prepared by reforming
coke oven gas by heat treatment and mixing with the refonned gas enriched in hydrogen gas one
20 of the gases selected from (i) a gas containing CO, (ii) combustion gas obtained by combustion
of flammable gas and oxygen, and (iii) oxygen.
[ilil65J
First, an embodiment reforming coke oven gas by heat treatment and mixing with the
reformed gas enriched in hydrogen gas a flammable gas containing CO and oxygen will be
25 explained with reference to FIG. 4. In this embodiment, as the refonning by heat treatment,
partial oxidation is utilized.
[0066]
Raw Material Coke Oven Gas (COG)
In the present invention, reformed COG obtained by heat decomposition of coke oven gas
30 (COG) emitted. in a coke oven, that is, crude COG, in a carbonization furnace to increase the
hydrogen and otherwise adjust the constituents is most preferably used as the raw material COG
from the viewpoint of reducing C02 emission. Alternatively, refined COG obtained by refining
the crude COG emitted in a coke oven and generally used as fuel in an iron making plant may be
used as the raw material COG. The raw material COG gas may be supplied t!·om the COG
35 supply source 1 shown in FIG. 4. As the COG supply source I, a COG gas holder etc. can be
used.
21
----- ----- ---:c; ---------
[0067]
The crude COG emitted at the time of coal dry distillation at the coke oven (not shown)
contains methane, ethane, and other aliphatic organic gases, benzene, toluene, and other aromatic
hydrocarbon light oil gases, tar gas mainly comprised of aromatic heavy hydrocarbons, etc.
5 Further, the moisture deposited on or contained in the coal used evaporates inside the coke oven
so the COG generally contains steam.
[0068]
In an embodiment using refined COG obtained by treating the crude COG in a
carbonization furnace, as !he main substance decomposed by heat in the hydrogen generation
l 0 reaction in the carbonization furnace, tar is suitable. This is because when decomposing by heat
the aromatic hydrocarbons of the main ingredient oflar, the remaining hydrocarbons after the
release of hydrogen easily grow into macromolecules comprised of two-dimensional aromatic
polycyclic structures whereby solid carbon granules of diameters of several 1.un to several mm
are easily obtained and whereby solid carbon is easily held in the carbonization furnace. By
15 holding the produced solid carbon in the carbonization furnace for a certain lime period, the
hydrogen which remained in the solid carbon also gradually disassociates as hydrogen gas, so the
heat decomposition is promoted much more. On the other hand, aliphatic organic substa11ces can
also be decomposed by heat, but the solid carbon generated at that time generally often becomes
an amorphous state structure with diamond-like crystal structures scattered at random. The solid
20 carbon is generated as ultratine particles with diameters of the nanometer to submicron size.
Therefore, it tends to be difficult to hold the generated solid carbon in the carbonization furnace
or separate and discharge it all together from the carbonization furnace. Further, in the case of
COG unavoidably containing a high concentration of hydrogen sulfide gas, in the hydrogen
generation reaction using a catalyst, the reaction of the tar generally proceeds at a faster reaction
25 speed than the reaction of the aliphatic hydrocarbons. On this point as well, heat decomposition
oftar is advantageous.
[0069]
Raising COG in Pressure
According to the present invention, the blast fumace 10 with the shaft part to which the reducing
30 gas is supplied is Ltsually operated at a pressure of several thousand kPa to 1 MPa, so to supply
gas from the shaft part 11 of the blast furnace to the inside of the blast furnace 10, the ordinary
pressure COG at the gas holder I has to be raised in pressure to at least the inside pressure at the
shaft pmi ofthe blast furnace. This rise in pressure may be performed using a compressor 2. For
the compressor 2, a commercially available one can be applied. For example, a multistage axial
35 tlow compressor or centrifugal type compressor can be used. A compressor operating a! the
temperature of the supply of gas a! the shaft part of the blast fum ace (about 900°C) is not
22
generally available, so the COG can also be compressed alan ordinary temperature part.
[0070]
Adjustment of flow Rate of COG
The flow rate of the hydrogen gas supplied to the shaft part II of a blast furnace is adjusted to
5 match with the operating state of the blast furnace I 0 by adjusting the flow rate oflhe raw
material COG. The tlow rate of the COG can be adjusted by a flow rate adjustment apparatus 3
suitably configured by combining a commercially available flowmeter, flow rate regulator,
computer, and other control devices. A high temperature specification flow rate regulator is not
generally available, so COG can also be adjusted in the flow rate at an ordinary temperature part.
I 0 In the embodiment of FIG. 4, the flow rate is adjusted after raising the pressure, but the order of
this may be suitably changed.
[0071]
Pariial Oxidation Refonning Reaction of COG
The raw material COG is mixed with oxygen gas in the patiial oxidation refom1ing reactor 5 and
15 part ofthe COG is made to bum (partial oxidation) to raise the COG to a temperature of over
1200°C and thereby raise the reaction speed. The methane and other hydrocarbons in the COG
are decomposed and reformed without using a catalyst so as to manufacture hydrogen gas. As
explained later, in the preset1t invention, it is not necessary to break down all of the hydrocarbons
in the raw material COG, so the gas temperature may be allowed to fall due to the absorption of
20 heat due to the steam reforming reaction occurring after the partial oxidation and become less
than the steam refotming reaction temperature before all ofthe hydrocarbons decompose. If
raising the temperature to a sufficiently high temperature over 1200°C at the time of pariial
oxidation, the subsequent steam reforming reaction will enable the majority of the hydrocarbons,
though not all, to be decomposed, so there is no problem.
25 [0072]
The oxygen gas is preferably supplied in the fonn of pure oxygen from the viewpoint of
the quality of the hydrogen gas manufactured. Oxygen-enriched air or other oxygen-containing
gas can also be supplied as the oxygen gas. The flow rate of supply of the oxygen gas (molar
flow rate) is preferably 0.4 to less than 0.5 ofthe total value of the molar flow rate of carbon
30 atoms contained in the hydrocarbons (methane etc.) in the COG (that is, 02/C=OA to less than
0.5) from the viewpoint of the quality ofthe gas. If the 02/C ratio is less than 0.4, hydrogen is
not sufficiently enriched at the time of the patiial oxidation, so it is not possible to sufficiently
manufacture the hydrogen gas required for hydrogen smelting in the blast furnace and the
hydrocarbon decomposition rate becomes excessively low and the restrictions on the constituents
35 ofthe reducing gas supplied to the shaft part ofthe blast furnace are not satisfied. Further, if the
02/C ratio is 0.5 or more, with a partial oxidation operation predicated on a nonequilibrium
23
-- -- -- ---- ---;-r
reaction like in the present invention, a large amount of steam generated due to combustion of
the hydrogen remains in the gas after the partial oxidation, so this is not preferable.
10073]
Preheating of COG
5 In the present invention, the flow rate of02 supplied at the time of partial oxidation is made the
minimum extent by preheating the raw material COG. For the preheating apparatus 4 for this,
various types of commercially available heat exchangers can be used. As the preheating method,
the outside heat system not causing contamination of the raw material COG is preferable. The
temperature of the raw material COG afler preheating is preferably made 800°C to 1000°C. !f
I 0 the preheating temperature is less than 500°C, the peak temperature of the gas temperature at the
time of partial oxidation becomes lower than the reforming reaction temperature during
refonning of the hydrocarbons and there is the problem that the hydrocarbons cannot be
sufficiently decomposed. Preheating up to a temperature of over I 000°C is no! a problem from
the viewpoint of the reactivity, but a high temperature unnecessary for decomposition of
15 hydrocarbons is reached at the time of partial oxidation, so the energy required for the excessive
preheating becomes wasted, so this is not preferable from the viewpoint of reducing C02
emission, Further, preheating up to a high temperature such as one over l000°C requires a
special heating apparatus, so this is not preferable from the viewpoint of capital costs.
20
[00741
Operating Conditions of Pa1tial Oxidation Step
Stoichiometrically, the 02/C ratio in the partial oxidation of the raw material COG can become
optimal when 0.5. This is because all of the H20 emitted by formula 4 due to the supply of
oxygen gas is consumed by the steam reforming reaction of formula 1 and because all of the
hydrocarbons are broken down into CO and H2 due to the steam reforming reaction, However, to
25 cause such a reaction under the pressure conditions of the reducing gas supplied to the shaft part
of a blast furnace, in terms of equilibrium theory, a 1300°C or more temperature has to be
maintained during the steam reforming occurring after the partial oxidation. In the case of a
temperature lower than this, for example an order of several% of hydrocarbons and a large
amount of H20 derived ti'om the excess 02 remain in the gas after partial oxidation. For
30 achieving such a high temperature by just partial oxidation, a large amount of02 has to be
supplied. It is also possible to cut the amount of supply of 02 by preheating the raw material gas,
but in the past, the exhaust heat generated in the plant was used for this preheating, so at the
highest, only preheating up to about 500°C was performed. This is because preheating up to a
temperature higher than this becomes disadvantageous in tem1s of heat efficiency. For this
35 reason, in conventional partial oxidation of hydrocarbons, the complete decomposition ofthe
hydrocarbons was aimed at and the 02/C ratio, in the case of using natural gas or naphtha or
24
---:'\: -- ---- ------~-:;:-
other pure hydrocarbon as a raw material, was 0.6 to 0.7 or so (if the hydrocarbon is methane, the
supplied 02 volume flow rate is 0.6 to 0.7 time the raw material volume flow rate) and, in the
case of using purified COG with a concentration of hydrocarbons of 30% or so as a raw material,
was 0.8 or more (ifthe hydrocarbon is methane, the supplied 02 volume flow rate is 0.24 time or
5 more the raw material volume flow rate). !fusing such a high 02/C ratio, if possible to maintain
a high temperature at the time of steam reforming, the residual amount of C02 becomes a level
of several% to I 0 odd%, while if not possible to maintain a sufficiently high temperature at the
time of steam reforming, J 0% or more steam remains, so in each case, the already explained
restrictive conditions relating to the constituents of the reducing gas supplied to the shaft pmi of
10 a blast furnace cannot be satisfied. In the present invention, reformed COG having a
concentration of hydrocarbons further smaller than refined COG (20% or so or less) is used as
the raw material, so the amount of oxygen supplied per flow rate of the raw material gas is
smaller than the case of using such gases as the raw material (if the hydrocarbon is methane and
the 02/C ratio is made 0.8, the supplied 02 volume flow rate is 0.16 time or less of the raw
15 material volume flow rate) and the amount of temperature rise due to partial oxidation is also
very small, so this is more disadvantageous in the point of maintaining the temperature required
for the steam reforming reaction.
{0075)
In the present invention, the concentration of hydrocarbons in the reducing gas is made to
20 become the already explained restricted range by mixing it with CO-containing gas to dilute the
residual hydrocarbons. In the present invention, complete decomposition of hydrocarbons is not
aimed at, so the 02/C may also be less than 0.5. The supplied 02 may be further reduced (ifthe
02/C ratio is 0.4 and the hydrocarbons are methane, the supplied 02 volume flow rate is 0.08
time or less the raw material volume flow rate), and the C02 and H20 in the reducing gas can be
25 made the already explained restricted ranges. Furthermore, in the present invention, to secure the
temperature required for steam reforming after pa1iial oxidation for a ce1iain time, as the method
of making up tor the deficient amount of temperature rise, preheating at 800°C to l000°C is
jointly used. Such high temperature preheating in the partial oxidation process is a cause of
deterioration ofthe heat efficiency compared with the prior art if viewing the partial oxidation
30 step alone, so in the past, such high temperature preheating had been considered difficult
economically. However, after partial oxidation, it is possible to directly supply the reducing gas
diluted by the CO-containing gas to the shaft part of a blast furnace, so if considering the fact
that the supply of heat energy for reheating the reducing gas aiter cooling it once so as to adjust
the constituents after partial oxidation in the prior art is unnecessary in the present invention etc.,
35 in the present invention, it is possible to slash the overall energy consumption, so in the present
invention, preheating at such a high temperature is possible. ln this way, by preheating the raw
25
---- ------- ---~-'C
material to 800°C to I 000°C, using reformed COG as the raw material, performing partial
oxidation combined with supply of oxygen making 02/C OA to less than 0,5, and diluting the gas
after partial oxidation by CO-containing gas in ajoint manner, in the present invention, it is
possible to manufacture reducing gas suitable as the reducing gas for supply to the shaft pa1i of
5 the blast furnace under conditions of reduced C02 emission.
[0076]
A burner or other igniting means (not shown) may also be provided inside of the partial
oxidation reforming reactor 5 or upstream of the partial oxidation reforming reactor 5. If the
inside walls of the partial oxidation reforming reactor are held at a temperature sufficiently
l 0 higher than the ignition point ofthc raw material COG, the partial oxidation reaction can be
stably continued inside the partial oxidation reforming reactor without relying on the temperature
of supply of the raw material COG or the supplied oxygen gas.
[0077]
The gas temperature after raising the temperature by combustion in the reactor 5 is
IS preferably made 1200°C to 1800°C in range. lfless than 1200°C gas temperature, the chemical
reaction speed is excessively slow, so if trying to proceed with the reforming operation at this
range oftemperature, the problem arises ofthe dimensions of the reactor becoming gigantic. If
the highest temperature of the gas exceeds 1800°C, there is the problem that the temperature of
the inside walls of the reactor which contact the gas becomes too high and the lifetime of the
20 furnace members is remarkably shortened. Due to the absorption of heat at the time of the steam
reforming reaction occurring after the partial oxidation, the gas temperature will fall at the
downstream side of the partial oxidation fumace and may become one of the above temperature
or less, but if the peak temperature of the gas after partial oxidation is in the above range, tbere is
no problem since the majority of the hydrocarbons in the raw material COG can be decomposed.
25 [0078]
The volume of the reactor 5 is preferably one by which the apparent average residence
time of the gas ([Reactor volume]/([Fiow rate of treated COG (standard state)]+[Fiow rate of
oxygen supplied from outside (standard state)])) becomes 5 seconds to 120 seconds. lflcss than
this range, the reactor residence time of the treated gas is excessively small and the problem
30 arises of the reforming reaction of the methane not sufficiently proceeding. Further, if over this
range, the reactor residence time is excessively large and the problem arises of excessive capital
costs being required.
]0079]
At the downstream side in the partial oxidation reforming reactor after the elapse of a
35 predetermined apparent average residence time, the gas can be considered to have been
sufficiently reformed, so gas at the downstream side of this will be called "reformed gas".
26
- ------- ---------~"-
[0080]
Supply of CO-Containing Gas
Next, CO-containing gas is supplied to the reformed gas in the pmiial oxidation reforming
reactor to dilute the reformed gas and reduce in particular the concentration of hydrogen gas in
5 the refom1ed gas to a suitable range. By supplying such a gas in a greater amount to the shaft
part of a blast furnace, it is possible to supply the larger amount of hydrogen gas contained in the
reformed gas to a deeper position inside the blast furnace (location of blast furnace closer to
center axis in radial direction).
[00811
1 0 The supply of CO-containing gas to the refom1ed gas in the partial oxidation reforming
reactor also acts to cause heat exchange (mixture) between the high temperature refmmed gas
and low temperature CO-containing gas to thereby obtain a temperature range suitable for the
reducing gas to be supplied to the shaft part of a blast fumace. Further, due to this, preheating of
the CO-containing gas to be supplied to the patiial oxidation reforming reactor becomes
15 unnecessary or can be greatly reduced in extent. Further, the refonned gas finishes being cooled
inside the patiial oxidation refonning reactor which inherently has heat resistance, so due to this,
in the downstream equipment, there is no longer a need for extreme heat resistance specifications
(for example: 1200°C or more), the lifetime ofthe equipment can be extended, and the apparatus
also becomes inexpensive.
20 [0082]
The CO-containing gas is supplied from a supply pmi provided at a location where gas
passes after the elapse of the above predetermined residence time inside the partial oxidation
reforming reactor 5 to the inside of the partial oxidation reforming reactor 5. This supply port
must be provided downstream from the location of supply of oxygen gas to the patiial oxidation
25 reforming reactor 5.
[0083]
The CO-containing gas is supplied by a CO-containing gas supplying means 9 comprised
of a CO-containing gas supply source 7, a CO-containing gas flow rate adjusting means 8, and a
CO-containing gas supply port to the partial oxidation reforming reactor 5 connected to the gas
30 pipe in that order.
[0084]
CO-Containing Gas
The necessary conditions of the CO-containing gas supplied to the reducing gas obtained at the
partial oxidation reforming reactor 5 are as to !lows:
35 ·It be mainly comprised of CO so as to secure the reducibility ofthe gas after dilution of COG.
· lt be dry gas not containing tar or other hydrocarbons or steam impeding the operation of the
27
---~-( ---- ---- -
blast furnace.
· It as much as possible not contain fb or C02 which might cause an endothermic reaction ti·om
the viewpoint of securing the temperature at the shaft part of the blast fumace.
It have a sufficiently small N2 content so as to avoid energy loss due to running useless gas
5 through the inside of the blast fumace.
[0085]
There is no existing inexpensive gas which satisfies all of these conditions, so the desired
gas is manufactured based on a specific raw material. As the raw material, for example, blast
furnace gas, conve11er gas, synthesis gas, etc. can be used. These gases all contain C02. From the
I 0 above-mentioned restriction 2 of the constituents of the reducing gas, the smaller the
concentration ofthis C02, the greater the reduced C02 emission, so when manufacturing the
CO-containing gas, means for removing C02 are applied. As the means for removing C02, for
example, a commercially available physical adsorption method CO separation apparatus or C02
separation apparatus can be used. The CO-containing gas to which the means for removing C02
15 has been applied should not contain l vol% (dry) or more of C02 so as to keep the detrimental
effect of heat absorption due to the C02 decomposition reaction which can occur in a blast
furnace from being manifested. That is, the concentration of C02 of the CO-containing gas
supplied to the partial oxidation reactor is preferably 0 vol% (dry) to less than l vol% (dry). In
the case of using synthesis gas or other gas containing H2 as the raw material, the concentration
20 ofH2 in the CO-containing gas for mixture with the gas after partial oxidation, which generally
has a concentration of H2 higher than the upper limit value 35% of the preferable concentration
of H2 in the reducing gas explained above, so as to obtain 35% or less of a reducing gas has to be
at least less than 35%. To use gas containing excessive 112 as CO-containing gas, it is possible to
use means for removing H2 to reduce the concentration ofH2. As the means for removing H2, it
25 is possible to use a commercially available membrane separation apparatus etc. The N2
concentration is also preferably at least less than 20 vol% from the viewpoint ofthc abovementioned
restrictions on the constituents of the reducing gas. For this reason, this can be
realized by reducing the amount of use and amount of mixture of air (that is, the N2 source) at
the time of manufacture ofthe CO-containing gas. However, to lower the amount of use and
30 amount of mixture of air at the time of manufacturing the CO-containing gas to the extremely
low concentration of less than I%, a large amount of additional energy has to be supplied, so this
is not preferable from the viewpoint ofreduced C02 emissions. For this reason, the N2
concentration is preferably I vol% or more.
35
[0086]
Supply of Manufactured Hydrogen-Containing Reducing Gas to Shaft Part of Blast
Furnace
28
----------:::-
The hydrogen gas-containing reducing gas adjusted by supply of CO-containing gas to a
temperature suitable for hydrogen gas for supply to the shaft part of a blast furnace is supplied to
the shat1 part II of the blast furnace (part around blast furnace shaft where plurality of through
holes arc provided from which hydrogen gas is supplied). For the structure and materials of the
5 shall part of a blast furnace, ones of the prior art can be applied.
[0087]
Water Content Reducing Means of COG
The coal supplied to the coke oven may be made to dry in advance using a known DAPS or
SCOPE21 furnace. If dry distilling the thus dried coal, it is possible to make the moisture in the
10 COG emitted decrease. Alternatively, in the case of a smaller system, it is also possible to store
the coal in a stock house for a long period of time of several months or more and allow the
moisture to naturally evaporate during that time. FIG. 5 shows a coke oven 11 to which a means
IIA for reducing the moisture of the emitted coke oven gas (COG) is attached. For example, a
DAPS, SCOPE 21, etc. tor reducing the moisture of coal may be made the moisture reducing
15 means llA and the coal dehydrated by the moisture reducing means IIA may be transported by
a belt conveyor or other coal conveying means II B to the coke oven 11.
100881
In some cases, it is also possible to supply the moisture ofthe coal to the coke oven
without decreasing it, extract the COG containing a high concentration of steam generated in the
20 coke oven, and run it through high temperature use zeolite or other adsorbent to thereby decrease
the moisture in the COG.
!00891
Carbonization Furnace
ln the present invention, if using the reformed coke oven gas (refined COG) obtained by treating
25 the crude coke oven gas from the coke oven 11 (FIG. 5) in the carbonization furnace as the raw
material gas, the carbonization furnace 12 (FIG. 5) is a furnace for reforming the hydrocarbons
(mainly tar gas) in the COG continuously supplied from the coke oven 11, separating the
hydrogen gas and solid carbon, and discharging reformed gas enriched in hydrogen gas to the
downstream side. The temperature inside the fumace is held at a temperature suitable tor a heat
30 decomposition reaction and the heat of reaction required for the hydrogen generation reaction,
mostly comprised of heat decomposition, is supplied by providing the carbonization furnace with
a heat supplying means (not shown) tor supplying heat from outside the furnace body (or by
providing the furnace with a heating element etc. for supplying heat from inside the furnace). To
supply this heal, general heating by an electric heater or direct flame heating can be used. The
35 carbonization furnace 12, to avoid combustion at that location of the solid carbon produced, has
a structure avoiding as much as possible the inflow oflhc source of oxidation of oxygen, air,
29
---------~"-
steam, etc. to the carbonization furnace. Specifically, no means for supplying oxygen to the COG
in the hydrogen generation reaction such as in a partial oxidation method is provided. Steam also
is not added to the COG other than what was originally contained in the COG. The reaction
temperature suitable for the heat decomposition reaction of tar is generally 650'C to 900°C in
5 range in the case of using a pyrolysis catalyst. lfless than this temperature range, if running the
COG through the carbonization furnace, the tar will condense and this condensate will close the
spaces between solid carbon particulates, so there is the problem that the carbonization furnace
will easily clog. Further, the pressure inside the carbonization furnace is preferably lower than
the pressure inside the coke oven. For example, the pressure inside the coke oven is usually over
I 0 I 0 Pa (gauge pressure), so the pressure inside the carbonization furnace may be made I 0 Pa
(gauge pressure) or less to maintain the passage of the COG. There is no particular lower limit of
the pressure inside the carbonization furnace, but from the viewpoints ofthe pressure resistance
of the carbonization furnace, the gas density inside the carbonization furnace, the necessary
vacuum apparatus capability (this sometimes becomes necessary), etc., it may be made -20000
I 5 Pa (gauge pressure) or more.
[0090]
Catalyst
Inside of the carbonization furnace 12, a pyrolysis catalyst (not shown) can be placed. For the
pyrolysis catalyst, for example, a catalyst comprised of a composite oxide containing nickel,
20 magnesium, cerium, and aluminum but not containing alumina, in which catalyst the composite
oxide uses a catalyst comprised ofNiMgO, MgAI204, and Ce02 crystal phases can be used.
[0091]
Gas Refining Apparatus
In the primary reformed gas extracted from the carbonization furnace 12, at least the tar, light oil,
25 benzene and other high boiling point hydrocarbons or moisture and other condensable gases can
be removed by a gas refining apparatus 13. The condensable gas can be removed by using a
water cooling apparatus of gas using a scrubber etc. or by using a distillation tower. If necessary,
treatment for removing sulfur or treatment for removing ammonia may also be added. The high
temperature primary refonned gas from the carbonization furnace 12 is cooled by treatment at
30 the gas refining apparatus 13 at least down to a temperature lower than the heat resistance
temperature of the gas conveyor apparatus 14, usually down to close to ordinary temperature.
[0092]
Gas Conveyor Apparatus
The gas conveyor apparatus 14 is an apparatus for taking in primary reformed gas from the
35 carbonization furnace 12 and for raising it in pressure and sending it to the partial oxidation
reforming apparatus 16 (explained later). For this reason, the gas conveyor apparatus 14 requires
30
5
----- -- - -,--------,---,-----c----
a head enabling the entrance side pressure to be maintained at -I 0 kPa or so and the exit side
pressure to be maintained at least at 0.2 MPa. generally 0.2 to I MPa or so. For the gas conveyor
apparatus 14, it is possible to use a commercially available multistage axial tlow compressor etc.
111093]
Preheating Apparatus
The primary refonned gas raised in pressure at the gas conveyor apparatus 14 is subsequently
sent to the reforming apparatus 16 for further reforming by partial oxidation. In this reforming
apparatus 16, gas combustion using oxygen gas is utilized to raise the temperature of the running
gas, but Jl·om the viewpoint of reducing the amount of C02 generated and from the prime units
10 of hydrogen, the amount of oxygen supplied should be set to the minimum necessary limit.
However, if raising the temperature of the ordinary temperature primary reformed gas by gas
combustion, the temperature of the running gas after being raised in temperature will often not
rise to an extent enabling promotion of decomposition of methane by steam refom1ing. For this
reason, it is possible to preheat the primary reformed gas from the carbonization furnace 12 by
15 the preheating apparatus 15, then raise the temperature of the running gas by gas combustion to
make the temperature of the running gas after being raised in temperature a suitable range. The
preheating temperature of the primary refonned gas is preferably 300 to 800°C or so.
[0094]
The primary refonned gas can be preheated in the preheating apparatus IS by, for
20 example, using a commercially available heat exchanger or by causing heat exchange with
combustion gas generated in a separately provided combustion furnace.
[0095]
Next, an embodiment in which coke oven gas is refotmed by heat treatment and in which
the refom1ed gas enriched in hydrogen gas is mixed with a combustion gas obtained by burning a
25 flammable gas and oxygen will be explained with reference to FIG. 5. In this embodiment,
reforming using heat decomposition in a carbonization furnace explained previously as
reforming by heat treatment (primary reforming) and further reforming in a partial oxidation
reforming apparatus (secondary reforming) are utilized. Other than the pat1s of the apparatus and
method explained below, it is possible to use an apparatus and method similar to the tirst
30 embodiment.
[0096]
Partial Oxidation Reforming Apparatus
The partial oxidation rcfonning apparatus 16 is an apparatus which mixes combustion gas with
the primary reformed gas to raise the temperature ofthc primary reformed gas to a temperature
35 greatly exceeding I 000°C (for example, 1500°C) and thereby increase the reaction speed and
break down the methane and other hydrocarbons in the primary rcfonncd gas without the use of
31
a catalyst and thus emit hydrogen gas or CO gas. As the partial oxidation reforming apparatus
16, any one can be used so long as satisfying these requirements.
[0097]
The reforming apparatus 16 has a burner 18 connected to it. The burner 18 is supplied
5 with oxygen gas and flammable gas. These are mixed and made to ignite inside the burner and
the combustion gas is exhausted to the inside of the reforming apparatus 16. As the burner 18, a
commercially available axial tlow burner etc. can be used.
[0098]
The oxygen gas is preferably supplied in the form of pure oxygen from the viewpoint of
I 0 the quality of the secondary reformed gas, but air or oxygen-enriched air or other oxygencontaining
gas can also be supplied as the oxygen gas.
[00991
The tlow rate of supply of oxygen gas (molar flow rate) is preferably 0.4 time to less than
0.5 time the total value ofthe molar flow rates of carbon atoms contained in the hydrocarbons in
15 the primary refonned gas and the hydrocarbons in the flammable gas (that is, corresponding to
02IC=OA to less than 0.5) from the viewpoint of the quality of the secondary reformed gas.
{OUlOj
On the other hand, the flow rate of flammable gas supplied to the burner 18 (molar flow
rate) is preferably 0.2 to 1 time the flow rate of oxygen gas (molar tlow rate).
20 [0101]
25
For the flammable gas, natural gas, liquefied petroleum gas, etc. can be used. Further,
naphtha, light oil, heavy oil, and other liquid fuels can also be used if atomized for supply to the
inside of the burner since they are fundamentally no different from flammable gas.
101021
Among these flammable gases, use of natural gas mainly comprised of methane is
particularly advantageous. Natural gas is advantageous in that the price per amount of heat
generated is inexpensive, the amount of C02 generated per amount of heat generated is relatively
small, the gas does not (like COG) contain hydrogen gas, so hydrogen is not consumed at the
time of combustion, etc.
30 101031
Oxygen gas and flammable gas may be supplied to the burner 18 at ordinary temperature
or may be supplied after preheating. If supplying them at less than the ignition temperature of the
flammable gas, it is necessary to provide an igniting means (not shown) at the bumer 18. For
example, it is possible to provide a pilot burner (not shown) at the burner 16 to make the mixed
35 gas of the i1ammable gas and oxygen gas ignite.
[0104]
32
The gas temperature inside the reforming apparatus J 6 has to be maintained at least at
J 000°C or more. The maximum temperature is preferably l 200 to 1800°C in range. This is
because if less than this temperature range. the chemical reaction speed becomes excessively
slow, so the problem arises orthe dimensions of the relorming apparatus 6 used as a reactor
5 becoming gigantic and because if over this temperature range, there is the problem that the
temperature of the inside walls ofthe reforming apparatus contacting the gas becomes too high
and the lifetime of the material forming the inside walls is remarkably sh01iened.
[0105]
A thermometer (not shown) may be provided inside !he partial oxidation reforming
I 0 apparatus 16 to measure the temperature of the gas inside the apparatus and this measured value
may be used as the basis to control the temperature of the gas inside the apparatus. For the
thennometer, an R-type or B-lype thermocouple covered by ceramic or another heat resistant
material for protection may be used.
[0106]
15 The volume of the reforming apparatus 16 used as the reactor is preferably one whereby
the apparent average residence time of the gas ([Volume of reaction vessel]/([Flow rate of treated
primary reformed gas (standard state )]+[Flow rate of combustion gas supplied from outside
(converted to ordinary pressure and I 00°C)])) becomes 30 seconds to I 00 seconds. If less than
this range, the residence time of the treatment gas in the reforming apparatus becomes
20 excessively small and the problem arises of the reaction not sufficiently proceeding. Further, if
over this range, the residence time in the reforming apparatus becomes excessively large and the
problem arises of excessive capital costs being required.
[0107]
Supply of Manufactured Reducing Gas {Secondary Refom1ed Gas) to Shaft Part of Blast
25 Furnace
The reducing gas (secondary reformed gas) containing hydrogen obtained from the partial
oxidation reforming apparatus 16 is supplied to the shaft part 7 of a blast furnace. In some cases,
before introduction into the blast furnace, the reducing gas may also be adjusted in temperature.
The art of supplying reducing gas to a blast furnace is broadly known. There is no need to
30 explain it in detail here.
[0Hl8]
Next, an embodiment mixing unburned flammable gas and oxygen with the reformed gas
enriched in hydrogen gas by reforming the coke oven gas by heat treatment will be explained
with reference to FIG. 6. In this embodiment, flammable gas is directly supplied to the pa1iial
35 oxidation refom1ing apparatus 16 in advance without being made to burn. Therefore, in this
embodiment, the burner 18 explained in FIG. 5 is not used.
33
[0109]
In the reforming apparatus 16 ofthis embodiment, the independent burner is eliminated
and the oxygen gas and the tlammable gas are closely and directly supplied to the reforming
apparatus. In this case, the supplied oxygen gas and flammable gas are in close proximity, so a
5 combustion region is formed near the gas supply pori. Here, mainly oxygen gas and tlammable
gas burn, so this combustion region plays substantially the same role as a burner. In some cases,
the oxygen gas and the flammable gas may be supplied to the inside of the reforming apparatus
together in advance.
10
[OlHl]
Further, in the embodiment shown in FIG. 6, a gas holder 19 is arranged between the gas
refining apparatus 13 and the preheating apparatus 15 and a first gas conveyor apparatus 14' and
a second gas conveyor apparatus 14" arc provided before and after it The gas holder 19 can
temporarily store the primary reformed gas. The operability is improved in that there is no need
to completely synchronize the production ofthe primary refonned gas and the production ofthe
15 secondary reformed gas. The capacity of the gas holder 19 can be suitably determined based on
the operating conditions ofthe coke oven 11 and the blast furnace 17. The entrance side and exit
side ofthe gas holder 9 are respectively provided with gas conveyor apparatuses 14', 14", so it is
possible to select the optimal gas conveyor apparatuses in accordance with the characteristics of
the operating conditions of the primary reformed gas production side and the secondary retom1ed
20 gas production side. For example, the first gas conveyor apparatus 14' docs not require pressure
boosting, so a Roots blower or other inexpensive apparatus can be applied. For the second
conveyor apparatus 14", a commercially available multistage axial flow compressor etc. can be
used. Needless to say, a configuration using a gas holder 19 and gas conveyor apparatuses 14',
14" before and after it can also be applied to the embodiment explained previously with
25 reference to FlG. 5.
[OlH]
30
The other apparatuses and equipment in the embodiment of FIG. 6 are similar to those in
the embodiment shown in FIG. 5.
[0112]
In the embodiment utilizing reforming by heat decomposition in the carbonization
furnace explained with reference to FIG. 5 and FIG. 6 (primary reforming) and further reforming
at the pmiial oxidation reforming apparatus (secondary reforming), the primary reformed gas is a
single type of flammable gas, so the primary reformed gas can also be used as the flammable
gas. In this case, the primary reformed gas does not necessarily have to be supplied by another
35 system to the burner 8 (FIG. 5) or the combustion region ofthe partial oxidation refon11ing
apparatus 16 (I'!G. 6). It is sufticient that oxygen gas alone be directly supplied to the inside of
34
s
the reforming apparatus. The space near the oxygen supply port inside the reforming apparatus
16 becomes the combustion region. This combustion region plays substantially the same role as a
burner.
[0113]
Note that, the primary reformed gas contains a large amount of hydrogen gas along with
methane. The speed of combustion of hydrogen gas is generally faster compared with methane
gas, so if oxygen is supplied inside the reforming apparatus 16, the hydrogen in the primary
reformed gas is consumed and steam is produced. If this gas is maintained at a high temperature
inside the reforming apparatus J 6, the generated steam reforms the methane to produce
1 0 hydrogen, so if a sufficient time period for holding the gas at a high temperature can be set inside
the refonning apparatus 16, there is no problem in breaking down the methane in the primary
reformed gas. However, if the time period for holding the gas is not sufficient, the secondary
reformed gas is exhausted before the steam reforming of the methane sufficiently proceeds, so it
becomes impossible to restore the hydrogen gas consumed by combustion. Therefore, if directly
IS supplying oxygen to the inside of the reforming apparatus 16, it is necessary to set the
dimensions of the reforming apparatus 6 used as the reaction vessel sufficiently large.
[0114]
If directly supplying oxygen gas into the primary reformed gas, it would be difficult to
separate the amount ofthe primary reformed gas of the combustion gas from the primary
20 reformed gas as a whole, so the tlow rate of supply of flammable gas in this case may be less
than 0.2 time the lower limit tlow rate of supply of oxygen gas (molar tlow rate) in the case of
supply as combustion gas to the refonning apparatus through the bumer 18.
EXAMPLES
25 [0115]
Using the following examples, the present invention will be further explained. This being
said, the present invention is not limited to these examples.
[0116]
Example I
30 The apparatus of the embodiment shown in FIG. 4 is used to produce hydrogen gas for supply to
the shaft pa11 of a blast furnace. However, instead of directly blowing the reducing gas to an
actual blast furnace, a gas recovery facility was provided at a location corresponding to where
the gas is blown to the shaft part of a blast furnace, the temperature and pressure conditions there
were set to typical operating conditions at the shaft part of the blast furnace, and the gas flowing
35 into the gas recovery facility was sampled and analyzed for composition. Specitlcally speaking, a
gas holder filled with refined COG as the raw material COG was used as the COG supply
35
source, then the COG from the gas holder was raised in pressure from ordinary pressure to I
MPa, then was preheated and supplied to the patiial oxidation reforming reactor to manufacture
reformed gas containing H2. The partial oxidation reforming ofthe COG is performed by
supplying oxygen gas without addition of steam. At the downstream side of!he region used for
5 the reforming reaction inside the partial oxidation refonning reactor (region allocated for
securing apparent average residence time considered required for reforming), CO-containing gas
is supplied to the inside of the reactor and mixed with the rcfom1ed gas to obtain reducing gas to
be supplied to the shaft pa1i of a blast furnace. Due to the heat exchange between the gases
mixed in the process of production of the reducing gas, the high temperature reformed gas
I 0 generated by the reaction is cooled, while due to the heating (preheating) ofthe ordinary
temperature CO-containing gas, the reducing gas temperature is made a value suitable for
reduction at the shaft part of a blast fumace (about 900°C). If with mixing with ordinary
temperature CO-containing gas, the above suitable temperature of the reducing gas could not be
obtained, the CO-containing gas was preheated, then mixed with the refom1ed gas. For
15 preheating the raw material COG and CO-containing gas, the heat exchanger attached to the gas
combustion tumace was used.
[OH7J
For the partial oxidation Tumace, one with an inside diameter of0.6 m and a length of2
m was used. The residence time of the raw material gas inside the partial oxidation furnace was
20 80 seconds predicated on converting the raw material gas to a flow rate in the standard stale.
10118]
The main constituents of the refined COG for raw material use were H2: 55%, CH4:
30%, CO: 7%, and C02: 2% (actually measured values ofretlned COG obtained by treating
crude COG from coke oven using coal not treated to reduce moisture). The CO-containing gas
25 for use for manufacturing the reducing gas is blast fum ace gas (BFG) treated by a physical
adsorption apparatus to remove C02. The main constituents ofthe CO-containing gas were CO:
80% and N2: 18% (actually measured values).
[0119]
To the patiial oxidation refonning reactor, CO-containing gas was supplied under the
30 following three conditions:
35
a. 0.8 time tlow rate ofreformed gas
b. I time now rate ofreformed gas
c. 2 times tlow rate of reformed gas
[0120]
The above refined COG was supplied to !he partial oxidation furnace and partially
oxidized to obtain the compositions of reformed gases shown in Table I. Table I shows the
36
results obtained under the following three partial oxidation conditions:
· Partial oxidation I: 02/C~0.48, raw material COG preheating temperature~ I 000°C
· Partial oxidation 2: 02iC~0.48, raw material COG preheating temperature~soooc
·Partial oxidation 3 (comparative example): 02/C~0.7, raw material COG preheating
S temperature~soooc
In terms ofthe compositions of the reformed gases, in each case, the concentration ofH2 greatly
exceeded 35%, so with this, the gases are not suitable as reducing gases for supply to the shaft
part of a blast furnace.
[0121]
I 0 [Table I]
15
20
Reformed gas Reformed gas Reformed gas
(partial oxidation 1) (partial oxidation 2) (pmiial oxidation 3)
CH4 0.03 0.06 0.06
C2H4 0.00 0.01 0.01
co 0.26 0.20 0.19
Mole
C02 0.01 0.01 0.02
fraction
H2 0.65 0.61 0.50
1'120 0.03 0.08 0.19
N2 0.02 0.02 0.02
[0122]
Next, the refonncd gases of Table 1 were used mixed with CO-containing gas under the
following conditions to manufacture reducing gases.
Reducing gas (I):
Refon:ned gas (partial oxidation 1) diluted by LO time the flow rate of the above COcontaining
gas
Reducing gas (2):
Refom1ed gas (partial oxidation 2) diluted by 1.0 time the flow rate of the above COcontaining
gas
Reducing gas (3):
Rcfom1ed gas (partial oxidation 2) diluted by 2.0 times the flow rate of the above COcontaining
gas
Reducing gas ( 4):
Refom1cd gas (partial oxidation 3) diluted by 2.0 times the flow rate of the above CO-
25 containing gas
[01231
The compositions of the reducing gases supplied to the shaft part of a blast furnace
obtained as a result are shown in Table 2. The concentrations of C02 and H20 in all examples
37
were of levels not problems as reducing gases to be supplied to the shaft part of a blast furnace.
Regarding the concentrations of the hydrocarbons CH4 and C2l l4. in the reducing gas (2), the
upper limit values of the restriction on the constituents ofthe reducing gas supplied to the shall
pmi of a blast furnace are exceeded and therefore not suitable. As opposed to this, !he same
5 reformed gas mixed with more CO-containing gas (3) satisfied the condition of concentration of
hydrocarbons. The other reducing gases also satisfied the above-mentioned restrictive condition
of the concentration of hydrocarbons. The £;C02 in the reducing gas ( 4) is equal to the absolute
value ofthe £;C02 cut, so the effect of cutting C02 added up through the manufacture of the
reducing gas and the hydrogen smelting at the blast furnace is not obtained. With the reducing
l 0 gases (l) to (3), the /\.C02 was smaller than the absolute value ofthe /\.C02 cut by hydrogen
smelting in the blast furnace so it is possible to cut the total amount of generation of C02 ofthe
time of manufacturing the reducing gas and hydrogen smelting at the blast furnace. However,
with the reducing gases (l) and (3), the £;C02 was close to the absolute value ofthe /\.C02 at the
blast furnace. This is because ofthe supply of the heat required for preheating the raw material
15 COG (case of I) and the supply of heat required for preheating the CO-containing gas for mixing
a large amount of CO-containing gas for diluting the concentration of hydrocarbons in the
reducing gas to an allowable value (case of3 and 4).
[111241
[Table 2)
Mole
fraction
/\.C02
CH4
C2H4
co
C02
H2
H20
N2
(mol/mol!J2)
20 [0125]
Reducing gas
(1)
0.01
0.00
0.53
0.00
0.33
0.02
0.10
0.12
Reducing gas Reducing gas Reducing gas
(2) (3) (4)
0.03 0.02 0.02
0.01 0.00 0.00
0.50 0.60 0.60
0.005 0.00 0.007
0.30 0.20 0.16
0.04 0.03 0.06
0.11 0.14 0.14
0.08 0.14 0.16
Fw1hermore, from the measurements, the following results were obtained:
· Peak temperature of refonned gas: l200'C to 1800°C in range
·Temperature of hydrogen gas supplied to shaft part of blast furnace: 800°C to 900°C in range
·Range of concentration ofH2 of hydrogen gas supplied to shaft pmi of blast furnace: 16% to
25 33%
[0126]
38
---------------~-~--~----:'!. --------- ---- ------- ~-,--------
At the reducing gases (l) and (3), the manufactured gas satisfied the required temperature
and composition conditions oflhe hydrogen gas supplied to the shalt part of a blast furnace.
[0127]
From the results of the simulation explained above, if making the flow rate of supply of
5 the reducing gas to the shaft part of a blast furnace a rate exceeding 0.42 time the flow rate of the
gas supplied to the blast furnace tuyere, it is possible to supply hydrogen to a deeper part ofthe
blast furnace and possible to enhance the hydrogen smelting effect at the blast furnace.
(OWl]
Example 2
I 0 COG extracted from a coke oven using coal reduced in moisture by a DAPS as a raw material
was reformed by a carbonization furnace and refined. The refonned COG recovered at a gas
holder used as the source of supply of COG was used as the raw material COG for a partial
oxidation refon11ing reaction.
15
[0129]
The reformed COG was manufactured as follows by an actual machine. Coal reduced in
moisture by a DAPS from I 0% to 4% was conveyed by a belt conveyor !o a stock vat above the
coke oven. For conveying the coal from the stock vat to the inside of!he coke oven, a
commercially available skip car was used. From a branch pipe provided at the coke raising pipe
of the coke oven, approximately 800°C reduced moisture crude COG was extracted by suction.
20 The extracted reduced moisture crude COG was supplied to the carbonization furnace by a gas
pipe maintained in temperature at its surroundings so as to keep the temperature from falling.
[0130]
The carbonization furnace had gas passage cross-section (horizontal plane) dimensions of
120 mmx900 mm and a gas passage direction height of 1200 mm. The layer of the granular
25 bodies in the carbonization furnace was formed while holding the catalyst filled in the
carbonization furnace (diameter 15 mm Ni-MgO-based catalyst) by a holder with a bottom of a
drainboard shape. The height was 600 mm. During operation, the carbonization fumace was
maintained at 800°C in temperature by outside heating.
30
[0131]
The crude reformed COG from the carbonization furnace was refined using a scrubber to
remove the tar and majority of moisture in the gas and obtain reformed COG. The gas
temperature of the reformed COG alter passing through the scrubber was about sooc.
10132]
The refined reformed COG was transferred by a Roots blower to a gas holder. A branch
35 was provided at the gas pipe to the gas holder, the reformed COG was extracted, then this was
supplied to a commercially available gas chromatography apparatus for on-line analysis of the
39
constituents.
[0133]
Based on the composition of the reformed COG obtained by analysis (sec Table 3),
partial oxidation rcfonning similar to Example 1 was performed (under conditions of 02/C~0.48
5 and a preheating temperature of reformed COG of 800°C). The rate of decomposition of the
hydrocarbons in the partial oxidation was 70%. The reaction was a nonequilibrium reaction.
Next, this reformed gas was mixed with 1.0 time the flow rate of CO-containing gas
(constituents similar to Example 1). As a result, reducing gas of the composition shown in Table
3 for supply to the shaft part of a blast furnace was obtained.
10 10134]
[Table 3]
Reformed COG Reformed gas
(manufacture in (partial oxidation 4) Reducing gas 4
carbonization furnace)
CH4 0.22 0.05 0.02
C2H4 0.03 0.01 0.00
co 0.09 0.17 0.48
Mole
C02 0.02 0.00 0.00
fraction
H2 0.61 0.68 0.35
H20 0.00 0.07 0.04
N2 0.03 0.02 0.10
!'.C02
- - 0.09
(mol/molH2)
[0135]
From the results of Table 3, the reducing gases obtained in this example satisfy all of the
above-mentioned restrictive conditions on the constituents of a reducing gas to be supplied to the
15 shaft part of a blast furnace. The !'.C02 also is a sufficiently smaller one of about half of the
absolute value ofthe !'.C02 at the blast furnace so it is possible to cut the C02 when added with
the amount of C02 cut by the hydrogen smelting at the blast furnace. Furthermore, comparing
the present example with the actual values of the refined COG composition obtained by treating
crude COG from a coke oven using coal not treated to reduce moisture as the raw material gas in
20 partial oxidation (see Example 1 ), it is learned that the reformed COG obtained from a coal raw
material treated to reduce moisture in the present example is increased in concentration oHh.
From this, it is shown that by using reformed COG obtained from a coal raw material treated to
reduce moisture so as to work the present invention, it becomes possible to supply a greater
amount of H2 to the blast furnace. Further, the present example is more advantageous than any of
25 the reducing gases of Example lin that the !'.C02 is smaller (except for reducing gas 2 not
40
suitable in composition) and in the point of reduced f..C02 emission.
[0136]
From the results ofthe simulation explained above, if making the flow rate of supply of
the reducing gas to the shaft pmi of a blast furnace a rate exceeding 0.42 time the t1ow rate of the
5 gas supplied to the blast furnace luyere, it is possible to supply hydrogen to a deeper pati of the
blast furnace and possible to enhance the hydrogen smelting effect at the blast furnace.
[0137]
Comparative Example I
A conventional type of partial oxidation reforming reactor not supplying CO-containing gas to
10 the inside ofthe partial oxidation reforming reactor was used to manufacture reformed gas. COcontaining
gas was separately independently heated to 800°C by outside heating using a heat
exchanger, then was mixed with the above reformed gas to find the AC02 when supplied to the
shaft part of a blast furnace. As the method for this, the amount of C02 emitted was calculated
from the measured value of the amount of heat consumption when independently making the
15 CO-containing gas rise in temperature to 800°C. Next, this was added to the A C02 of the
reducing gas 3 of Example I to calculate the overall AC02. As a result, the f.. C02 was 0.19
molC02/molH2· This is a value greatly exceeding the results of Example I shown as a preferable
example (reducing gases (1) and (3) of Table 2) and exceeding the absolute value of the f..C02
emission at the blast furnace (0.16 moiC02/moiH2), so the C02 cannot be cut. This is due to the
20 heating efficiency of the CO-containing gas in the present comparative example being lower
compared with the present invention.
[0138]
Below, a comparison will be made with a method of manufacture of hydrogen gas for
supply to the shaft part of a blast furnace using another method of retonning using COG as a raw
25 material.
[0139]
Comparative Example 2
Catalytic Steam Reforming of Crude COG
Here, an actual oven was operated for 2 hours and the following procedure was followed to
30 manufacture hydrogen gas tor supply to the shaft part of a blast furnace from crude COG. The
crude COG extracted from the coke oven was treated by a catalytic reforming reactor (with
steam added (S/C (number of molecules ofH20/number of atoms ofC in hydrocarbons) =2) at
700°C or more (Ni-MgO-based catalyst used) to steam reform it, then was refined by a scrubber
to manufacture reformed COG. After gas sampling, the reformed COG was raised in pressure
35 (0.3 MPa) and raised in temperature (800°C) then supplied to the shaft part of a blast furnace.
Just the moisture in the crude COG is not sufficient for steam reforming, so 800°C steam was
41
--------- ----------,
added from the outside so that S/C~2 a! !he catalytic reforming reactor.
[0140]
The chemical composition ofthe hydrogen gas supplied to the shaft part of a blast
furnace obtained as a result and the actual value of the amount of C02 emitted llC02 during
5 manufacture of hydrogen are shown in Table 4. /lC02 was calculated trom the C02 in the
hydrogen gas supplied to the shaft pari of a blast furnace and the theoretical amount of C02 in
the combustion exhaust gas in the case of obtaining the theoretical heat of reaction in the
catalytic steam reforming reaction+ the energy required for raising the temperature and raising
the pressure ofthe reformed COG by complete combustion of natural gas.
10 [0141]
[Table 4]
Hydrogen gas supplied to shaft part of blast furnace
manufactured by catalytic steam reforming of crude COG
CH4 0.22
C2H4 0.01
co 0.06
Mole
C02 0.11
fraction
H2 0.58
H20 -
N2 0.02
L1C02
0.43
(mollmolH2)
[0142)
ln the results of Table 4, the concentration of methane and concentration of C02 were
excessive, so the gas was not suitable as hydrogen gas for supply to the shaft of a blast furnace.
15 Further, it was learned that with just a retonning step, the A C02 exceeded the allowable value
(0.16 moiC02/molH2) so was excessive.
[0143]
Comparative Example 3
Partial Oxidation Reforming of Crude COG
20 The manufacture of hydrogen gas for supply to the shaft pmi of a blast furnace by partial
oxidation retonning of crude COG described in Japanese Patent Publication No. 2001-220584
will be studied next.
[0144]
In Japanese Patent Publication No. 2001-220584, crude COG extracted from a coke oven
25 is reformed by partial oxidation by addition of pure oxygen (using the crude COG itself as the
flammable gas), then refined by a scrubber to obtain rcfom1ed COG. Consider supplying this
42
'- ---- - ------ -----.,----,----
reformed COG as the reducing gas (hydrogen gas supplied to shaft part of a blast furnace) to the
shaft part of a blast furnace. The chemical composition of the reformed COG obtained by partial
oxidation shown in the examples of Japanese Patent Publication No. 200l-220584A and the
amount of C02 emitted L\C02 during production of hydrogen calculated from the amounts of
5 C02 emitted and the amounts of hydrogen emitted ofthe same are shown in Table 5.
!0145]
[Table 5]
Mole
traction
L1C02
CH4
C2ll4
co
C02
H2
H20
N2
(mol/molAH2)
[0146]
Hydrogen gas supplied to shaft part of blast furnace
manufactured by partial oxidation reforming of crude COG
0.02
0.00
0.23
0.08
0.65
-
0.01
0.24 or more
Here as well, it was learned that with just the reforming stage, the AC02 exceeded the
I 0 above allowable value (0.16 molC02/molH2) and was excessive. Further, the concentration of
C02 also greatly exceeded the upper limit concentration as a reducing gas supplied to the shaft
of a blast fum ace. This was also not suitable in terms of constituents.
[0147]
Comparative Example 4
15 Catalytic Steam Reforming of Refined COG
20
Catalytic steam reforming of refined COG (crude COG retlned to remove the majority of the tar,
BTX (benzene and other aromatic compounds), moisture, sulfides, and nitrides to obtain fuel
gas. Widely used as fuel in ironmaking plants) will be studied next
[0148]
Refined COG from the gas holder was raised in temperature (800°C) and treated by a
catalytic reactor (steam added (S/C~2), reaction temperature 700°C or more, Ni-MgO-based
catalyst used) to manufacture reformed COG. This was cooled, raised in pressure (0.3 MPa),
then raised in temperature by indirect heating (800°C) to obtain a gas for supply to the shaft part
of a blast furnace. The composition of the refom1ed COG was found by a small scale test.
25 Assuming this process, the reason why not directly supplying high temperature reformed COG to
the shaft part of a blast furnace is as follows: With this process, due to the residual H2S
43
contained in a large amount in the refined COG, the catalyst is poisoned and loses activity in a
short period of time (several hours to several tens of hours). Each time the catalyst loses activity,
the reforming operation has to be suspended and a catalyst regeneration operation has to be
performed. Therefore, the operation cannot be said to be a continuous reforming operation. For
5 this reason, it is difficult to directly connect such a batch type reaction apparatus to the shaft part
of a blast furnace where continuous supply of hydrogen gas is sought for securing stability of
operations (gas holder or other production butfer is necessary).
[OWl]
The amount of C02 emilled l'l.C02 during production of hydrogen was calculated from
I 0 the C02 in the above constituents and the theoretical amount of C02 in the combustion exhaust
gas in the case of obtaining the theoretical heat of reaction in the steam refonning
reaction+energy required for raising temperature and raising pressure of reformed COG by
complete combustion of natural gas. The results are shown in Table 6.
[0150]
15 [Table6]
Composition of reducing gas
CH4 0.01
C2H4 0.00
co 0.10
Mole
C02 0.21
fraction
H2 0.66
H20 -
N2 0.02
ll.C02
0.70
(mol/moiH2)
[0151]
In Table 6, the concentration of C02 exceeds the upper limit concentration of the
reducing gas supplied to the shaft part of a blast furnace, so is not suitable. Further, the 6.C02
exceeds the above allowable value (0.16 mo!C02/moiH2), so the gas manufactured in this
20 example is not suitable as the reducing gas to be supplied to the shaft pmi of a blast furnace.
!0152]
From the above results, in the typical prior art, it is diftlcult to eftlciently manufacture
hydrogen gas for supply to the shaft part of a blast turn ace under the condition of reduced C02
emission. The superiority of the present invention is clear.
25 [0153]
In the following example, crude COG obtained ti·om a coke oven without using a
moisture reducing means and reduced moisture crude COG obtained from a coke oven operating
44
-------------- --~,c;-
using a DAPS as a moisture reducing means and reducing the coal moisture were used as the raw
material gases. The chemical compositions of the crude COG and reduced moisture crude COG
are shown in Table 7.
[0154]
5 [Table 7]
Crude COG
Reduced moisture
crude COG
CH4 0.22 0.25
C2H4 0.04 0.04
co 0.05 0.06
Mole
C02 0.02 0.02
fraction
H2 0.39 0.44
H20 0.25 0.17
N2 0.03 0.03
[0155]
Comparative Example 5
COG extracted from a coke oven using coal treated to reduce moisture by DAPS was treated in a
carbonization furnace (temperature 700°C or more, Ni-MgO-based catalyst used) to manufacture
I 0 primary reformed gas. This was passed through a scrubber to refine it, then was raised in
pressure (0.3 MPa) and raised in temperature, without pa1iial oxidation, by indirect heating
(800°C) and was supplied to the shaft part of a blast furnace.
[0156]
In the treatment to reduce moisture by DAPS, the coal moisture was reduced from 7% to
15 4%. The coal reduced in moisture was conveyed by a belt conveyor to a stock vat above the coke
oven, then was conveyed by a commercially available skip car from the stock vat to the inside of
the coke oven. From a branch pipe provided at the coke raising pipe of the coke oven,
approximately 800°C reduced moisture crude COG was extracted by suction. The extracted
reduced moisture crude COG was supplied to the carbonization furnace by a gas pipe maintained
20 in temperature at its SUJToundings so as to keep the temperature from falling.
[0157]
The carbonization furnace had gas passage cross-section (horizontal plane) dimensions of
120 mmx900 mm and a gas passage direction height of 1200 mm. The layer of the granular
bodies (catalyst layer) in the carbonization furnace was formed while holding the catalyst
25 (diameter 15 mm) filled in the carbonization fumace by a holder with a bottom of a drainboard
shape. The height was 600 mm. During operation, the carbonization Jumace was maintained at
800°C in temperature by external healing and was operated for 2 hours to generate 4 kg of coke.
Unless otherwise indicated, the coke (solid carbon) deposited at the catalyst layer ofthc
45
s
carbonization furnace was not separated and recovered from the catalyst layer during operation.
If periodically separating and recovering the coke (solid carbon) deposited on the catalyst layer,
the operating time was made 24 hours.
[0158]
As the retlning apparatus, a scrubber was used. The tar and majority of moisture in the
reduced moisture crude COG were removed to manufacture the primary reformed gas. The
temperature of the gas after passing through the scrubber was about 50°C. A branch for sampling
use was provided at the gas passage pipe at the exit side of the scrubber, the primary reformed
gas was extracted, then this was supplied to a commercially available gas chromatography
I 0 apparatus for on-line analysis of the constituents. The results of analysis are shown in Table 8
IS
(""Heat decomposition of reduced moisture crude COG").
[0159]
[Table 8]
Mole
fraction
LI.C02
CH4
C2H4
co
C02
H2
H20
N2
(mol/molH2)
[0160]
Heat decomposition of reduced
moisture crude COG
0.!8
0.03
0.10
0.02
0.66
0.00
0.02
0.13
The amount of C02 emitted during manufacture of hydrogen was calculated from the
amount of C02 in the primary reformed gas and the theoretical amount of C02 in the
combustion exhaust gas in the case of obtaining the theoretical heat of reaction in the above heal
decomposition reaction+energy required for raising the temperature and raising the pressure of
the primary refonned gas by complete combustion of natural gas. The results of calculation are
20 shown in Table 2 as the ;\C02 values. The obtained value (0.13%) is within the range of the
allowable value of the amount of C02 generated when producing hydrogen allowed when
producing the above-mentioned I mol of hydrogen gas (0.16 mo!C02/molH2) (in NPTL 2,
amount of C02 emitted during manufacture of hydrogen allowed when producing hydrogen gas
I mol), while the concentrations of methane and hydrogen are excessive. With this, application
25 to reducing gas for supply to the shaft part of a blast furnace is not possible.
[0161]
46
Comparative Example 6
The secondary reformed gas chemical composition and the amount of C02 emitted during
manufacture of hydrogen combining primary and secondary reforming in the case of using
primary reformed gas obtained by heat decomposition ofthc reduced moisture crude COG of
5 Comparative Example 5 with an amount of C02 emitted during manufacture of hydrogen within
the above range of allowable values to manufacture the secondary reformed gas by catalytic
steam reforming were calculated by thermodynamic calculations assuming equilibrium
conditions at the reaction temperature of the secondary reforming. Regarding the secondary
reforming, the values of the amounts of generation ofthe constituents at the time of 100%
10 methane decomposition obtained by equilibrium calculations and the values obtained when
making the amounts of generation of the constituents respectively 70% ofthe values at the time
of about 100% methane decomposition and assuming 30% of methane in the primary retonned
gas remaining as reformed gas were used (in reforming, about I 00% methane decomposition
(equilibrium) is not always obtained, so an example where methane is incompletely decomposed
15 will also be studied.) Table 9 shows the amounts of generation of the constituents at the time of
I 00% decomposition ofthe methane used and the amounts of generation of the constituents at
the time of 70% decomposition.
(Ol62J
[Table 9]
Mole
fraction
A C02
CH4
C2H4
co
C02
H2
H20
N2
( mol/mo1H2)
20 [0163]
Equilibrium catalytic steam Nonequilibrium catalytic steam 70%
reforming of reduced moisture reforming of reduced moisture crude
crude COG primary reformed gas COG primary refonned gas
0.00 0.04
0.00 0.01
0.16 0.09
0.03 0.02
0.68 0.65
0.12 0.19
0.01 0.02
0.19 0.19
The constituents of the gas obtained by a steam refonning reaction or partial oxidation
reaction (no catalyst) under conditions greatly exceeding I 000°C are known to be close to the
equilibrium composition at the reaction end temperature (substantially the reactor exit side
temperature) if sufficiently setting the residence time of the gas in the reactor, so by calculating
25 the equilibrium constituents, it is possible to evaluate the reforming performance of a steam
47
reforming reaction or partial oxidation reaction (no catalyst) under conditions greatly exceeding
!000°C.
[0164]
The secondary reformed gas obtained by catalytic steam reforming was manufactured by
5 raising the primary reformed gas in temperature (to 800°C) and treating it in the catalytic reactor
(steam added (SIC (number of molecules of H20/number of atoms of C in hydrocarbons) ~2.
reaction temperature 700°C or more, and Ni-MgO-bascd catalyst used). The thus manufactured
secondary reformed gas was cooled once, raised in pressure (0.3 MPa), then raised in
temperature by indirect heating (800°C) to obtain a gas to be supplied to the shaft pati of a blast
I 0 fumace.
10165]
The amount of C02 emitted during manufacture of hydrogen was calculated from the
C02 derived from the energy supplied at the time of primary reforming, the C02 in the above
constituents, and the theoretical amount of C02 in the combustion exhaust gas in the case of
15 obtaining the theoretical heat of reaction in the above steam refom1ing reaction+energy required
for raising temperature and raising pressure of secondary reformed gas by complete combustion
of natural gas. The results are shown in Table 9.
[01661
In both the equilibrium composition at the time of l 00% methane decomposition and the
20 nonequilibrium 70% reformed composition, the amount of C02 emitted during manufacture of
hydrogen exceeded the above allowable value (0.16 mo!C02/molH2) so was excessive.
Accordingly, the secondary reformed gas of this example is not suitable as the reducing gas for
supply to the shaft part of a blast fumace. Furthermore, the moisture and hydrogen in the
secondary reformed gas were excessive (allowable value: 10%). With that, supply to the shaft
25 part of a blast furnace is not possible.
[0167]
Comparative Example 7
The catalytic steam reforming of crude COG (COG obtained from coke oven without using
moisture reducing means, for composition, see Table 7) will be explained next.
30 [0168]
Crude COG extracted from a coke oven (operated for 24 hours) was treated by a catalytic
reactor (800°C steam added (S/C~2), reaction temperature 700°C or more, Ni-MgO-based
catalyst used) to manufacture secondary refonned gas. This was passed through a scrubber to
reilne it, then was raised in pressure (0.3 MPa) and raised in temperature by indirect heating
35 (800°C) to obtain gas for supply to the shaft part of a blast furnace. As explained in Comparative
Example 6, the amounts of generation of the constituents of the secondary reformed gas at the
48
- ---- -------------;-
time of I 00'% methane decomposition and the amounts of generation of the constituents at the
time of70% decomposition were found by calculation. FUiiher, the amount of C02 emitted
during manufacture of hydrogen was calculated from the C02 in the above constituents and the
theoretical amount of C02 in the combustion exhaust gas in the case of obtaining the theoretical
S heat of reaction in the above catalytic steam reaction+energy required for raising the temperature
and raising the pressure of the reformed gas by complete combustion of natural gas._Thc
obtained results are shown in Table 10.
[0169]
[Table I 0]
Mole
fraction
CH4
C2H4
co
C02
H2
FbO
N2
!'.C02
(mol/molH2)
10 [0170]
Catalytic steam
reforming of
crude COG
0.22
0.01
0.06
0.11
0.58
-
0.02
0.43
Equilibrium partial
Nonequilibrium partial
oxidation of crude COG
oxidation 70% refom1ing
primary refom1ed gas
of crude COG primary
reformed gas
0.01 0.05
0.00 0.00
0.26 0.19
0.02 0.02
0.63 0.61
0.07 0.11
0.01 0.02
0.32 0.38
In both the equilibrium composition at the time of 100% methane decomposition and the
nonequilibrium 70% reformed composition, the amount of C02 emitted during manufacture of
hydrogen exceeded the above allowable value (0.16 molC02/molH2) so was excessive.
Accordingly, the secondary refonned gas of this example is not suitable as the reducing gas for
15 supply to the shaft part of a blast furnace.
[0171]
Comparative Example 8
The example of manufacture of primary reformed gas by heat decomposition of the reduced
moisture crude COG in a carbonization furnace and manufacture of secondary refom1ed gas by
20 catalytic steam reforming will be explained.
10172]
For manufacture of the primary reformed gas, primary reformed gas obtained by heal
decomposition of the reduced moisture crude COG of Comparative Example 5 was used. Next,
the primary reformed gas was raised in temperature (800°C) and was treated by the catalytic
49
reactor (steam added (S/C=2, reaction temperature 700°C or more, Ni-MgO-based catalyst used)
to manufacture the secondary reformed gas. This was cooled once down to ordinary temperature,
then raised in pressure (0.3 MPa) and raised in temperature (800°C) to obtain gas for supply to
the shaft part of a blast furnace. As explained in Comparative Example 6, the amounts of
5 generation of the constituents at the time of I 00% methane decomposition of the secondary
reformed gas and the amounts of generation of the constituents at the time of70% decomposition
were found by calculations.
[0173]
The amount of C02 emitted during manufacture of hydrogen was calculated from the
I 0 C02 derived ti·om the energy supplied at the time of primary reforming, the C02 in the above
constituents, and the theoretical amount of C02 in the combustion exhaust gas in the case of
obtaining the theoretical heat of reaction in the above catalytic steam reforming reaction+energy
required for raising temperature and raising pressure of secondary refom1ed gas by complete
combustion of natural gas. The results are shown in Table II.
15 {0174]
fTable II]
Equilibrium steam reforming of Nonequilibrium steam 70%
reduced moisture crude COG refonning of reduced moisture crude
primary reformed gas COG primary refom1ed gas
CH4 0.00 0.04
C2H4 0.00 0.01
co 0.16 0.10
Mole
C02 0.03 0.02
fraction
H2 0.66 0.60
H20 0.13 0.21
N2 0.01 0.02
~C02
0.21 0.21
(mol/mo1H2)
10175]
In both the equilibrium composition at the time of 100% methane decomposition and the
nonequilibrium 70% reforming composition, the amount of C02 emitted during manufacture of
20 hydrogen exceeded the allowable value (0.16 molC02/moiH2) and was excessive. Accordingly,
in this example, the secondary reformed gas is not suitable as reducing gas for supply to the shaft
pmi of a blast furnace. Furthermore, the moisture and hydrogen in the secondary reformed gas
are excessive. With this as is, supply to the shafi part of a blast ti.Jmace is not possible.

CLAIMS
[Claim I]
A method for supplying a hydrogen-containing reducing gas to a shaft part of a blast
furnace, the method comprising manufacturing a reducing gas by raising a temperature inside a
5 reactor in which an oxygen-containing gas is supplied to a preheated coke oven gas to 1200 to
1800°C to reform the coke oven gas and thereby produce reformed gas enriched in hydrogen gas,
then mixing the CO-containing gas with that reformed gas in the reactor to adjust the
concentration of hydrogen to 15 to 35 vol% (wet) and supplying the reducing gas to the shaft
part of the blast furnace under a condition of a ratio of a flow rate of blowing the reducing gas to
I 0 the shaft part I a flow rate of blowing the reducing gas to the tuycre > 0.42.
[Claim 2]
The method for supplying reducing gas to a shaft part of a blast furnace according to
claim l wherein the oxygen-containing gas is oxygen gas and the method of refonning the gas
15 by raising the temperature in the reactor to 1200 to l800°C is pa.iial oxidation ofthe preheated
coke oven gas.
[Claim 3]
The method for supplying reducing gas to a shaft part of a blast furnace according to
20 claim 1 wherein the oxygen-containing gas is steam produced by combustion of hydrocarbons
and the method of reforming the gas by raising the temperature in the reactor to 1200 to 1800°C
is mixing combustion gas of the hydrocarbons with the preheated coke oven gas.
[Claim 4]
The method for supplying reducing gas to a shaft part of a blast furnace according to
claim 1, further comprising:
a) a step of raising the pressure of the coke oven gas,
b) a step of adjusting a flow rate ofthe coke oven gas,
c)
d)
a step of preheating the coke oven gas, and
a step of raising the temperature of the preheated coke oven gas inside the reactor
in which oxygen gas is supplied to 1200 to 1800°C and refom1ing the gas by pa1iial oxidation to
produce reformed gas enriched in hydrogen gas, then mixing into that reformed gas the COcontaining
gas in the reactor to adjust the concentration of hydrogen of the reformed gas to 15 to
35 vol% (wet) and the temperature to 800 to 1 000°C to produce reforming-use hydrogen gas tor
35 supplying to the shaft part ofthe blast fum ace.
[Claim 5]
The method for supplying reducing gas to a shaft part of a blast furnace according to
claim 4, wherein a concentration of CO in the CO-containing gas is 50 vol% to less than 99 vol%
(dry), a concentration of C02 is 0 vol% (dry) to less than I vol% (dry), a concentration ofH2 is 0
5 vol% (dry) to less than 35 vol% (dry), and a concentration ofN2 is I vol% (dry) to less than 20
vol% (dry),
[Claim 6]
The method for supplying reducing gas to a shait part of a blast furnace according to
10 claim 4, wherein the CO-containing gas is blast furnace gas, converter gas, or synthesis gas
treated to remove C02.
[Claim 7]
The method for supplying reducing gas to a shaft part of a blast furnace according to
15 claim 4, wherein the hydrogen-enriched refonned gas contains a hydrocarbon gas in an amount
ofl%to5%.
[Claim 8]
The method for supplying reducing gas to a shaft part of a blast furnace according to
20 claim 4, wherein a flow rate of supply (molls) of the oxygen gas is 0.4 to less than 0.5 lime the
flow rate of supply (molls) of carbon atoms contained in the hydrocarbons in the coke oven gas.
[Claim 9]
The method for supplying reducing gas to a shaft part of a blast furnace according to
25 claim 4, wherein as the coke oven gas, reformed coke oven gas obtained by treating crude coke
oven gas, obtained from a coke oven provided with means for reducing a moisture in crude coke
oven gas emitted, in a carbonization tum ace held at 700°C or more to break down the
hydrocarbons in the crude coke oven gas is used.
30 [Claim 10]
35
The method for supplying reducing gas to a shaft part of a blast furnace according to
claim 4, wherein the step of raising the pressure of the coke oven gas and the step of adjusting
the flow rate of the coke oven gas are performed in that order or in reverse order before the step
of preheating the coke oven gas.
[Claim I J]
52
The method for supplying reducing gas to a shaft part of a blast furnace according to
claim 1, !utiher comprising
a) a step of running coke oven gas J1·om the coke oven through a carbonization
furnace and breaking down the hydrocarbons in the coke oven gas into coke and hydrogen to
5 thereby make the concentration of hydrogen increase,
10
b) a step of removing the tar and at least part of the moisture in the gas run through
the carbonization furnace to manufacture a first reformed gas,
c)
d)
e)
a step of raising the pressure of the first reformed gas,
a step of preheating the raised pressure tlrst reformed gas,
a step of supplying the preheated first reformed gas to a partial oxidation
reforming apparatus and supplying combustion gas to that partial oxidation reforming apparatus
to further reform the hydrocarbons in the first reformed gas to make the concentration of
hydrogen increase to manufacture a second reformed gas, and
f) a step of supplying the second reformed gas from a gas supply port leading to the
15 shaft pa1i of the blast furnace to the inside ofthc blast furnace.
[Claim 12]
The method for supplying reducing gas to a shaft part of a blast fumace according to
claim II, further comprising raising the pressure of the first reformed gas to at least 0.2 MPa in
20 pressure.
[Claim 13]
The method for supplying reducing gas to a shaft part of a blast furnace according to
claim II, fmiher comprising preheating the first reformed gas to 800°C to I 000°C.
[Claim 14]
The method for supplying reducing gas to a shaft part of a blast furnace according to
claim II, further comprising supplying combustion gas to the partial oxidation reforming
apparatus by
30 (i) supplying combustion gas obtained by supplying oxygen gas and flammable gas
35
to a burner,
(ii) supplying oxygen gas and flammable gas to the partial reforming apparatus to
generate combustion gas inside that partial oxidation reforming apparatus and supplying the
same, or
(iii) supplying oxygen gas to the inside of the partial oxidation reforming apparatus to
make parl of the first refmmed gas burn and supplying the same.
53
[Claim 15]
The method for supplying reducing gas to a shaft part of a blast furnace according to
claim 11, further comprising, before preheating the first reformed gas, temporarily holding the
5 raised pressure gas in a gas holder and further raising the pressure of the gas from this gas
holder.