OOOl] The present invention relates to an a i r pollution
~ontrol~systeimn which discharge of an amine absorbent to
the outside of the system is significantly suppressed when
absorbing and removing GOZ in a flue gas by the amine
absorbent.
Background
[0002] In recent years, as one of causes of a global
warming phenomenon, a greenhouse effect due to COz has been
pointed out, and countermeasures against the effect have
also become an internationally urgent need in protecting
the global environment. A source of generation of C02
ranges in various fields o f human activities in which
fossil fuel is combusted, and a demand for suppressing the
discharge tends to be further strengthened. Accordingly,
directed at a power generation apparatus such as a thermal
power plant that uses a large amount of fossil fuel, a
methcd of removing and reccverihg CO2 i n a flue gas by
bringing the flue gas of an industrial apparatus, such as a
b o i l e r and a gas turbine, into contact with an mine-based
GOz absorbent, arid an air p o l l u t i o n control system that
stores the recovered C02 without releasing it to t h e
atmosphere have been extensively studied.
[00031 A CO2 recovery u n i t having a process of bringing
a flue gas and a C02 absorbent into contact with each other
in a COz absorber (hereinafter, a l s o simply r e f e r r e d t o as
l l a b ~ ~ ~ b e ralnld) a, process of heating the CO2 absorbent:
that has absorbed C02 i n a CO2 absorbent regenerator
(hereinafter, also simply referred t o as a "regenerator"),
diffusing C02, regenerating the COa absorbent and
c i r c u l a t i n g the absorbent to the CQ2 absorber again to
reuse the CQ2 absorbent, as a process of removing and
recovering COZ from the flue gas using the above-described
amins-based C02 absorbent, has been suggested (for exanple,
see Patent Literature 1).
[0004.1 In the CO2 absorber, the f l u e gas is brought into
countercurrent contact, for example, with the arnine-based
Con absorbent such as alkanolamine, C02 in the fiue gas is
absorbed t o the COn absorbent by a chemical reaction
(exothermic reaction), and the f l u e gas a f t e r removal of
10 COz is released out of the system. The COa absorbent t h a t
has absorbed C02 is also called a r i c h s o l u t i o n . The r i c h
solution is increased i n pressure by a pump, heated i n a
heat exchanger by the high-temperature COa absorbent (lean
s o l u t i o n ) obtained by diffusion of COz and regeneration in
the regenerator, and supplied to the regenerator.
[OOOS] In the C02 recovery process using the GO2
absorbent, the C02-free flue gas obtained by removing COn
from the flue gas is released to the atmosphere. However,
since a small p a r t of a small amount of amine absorbent is
present i n the released gas, it is necessary to reduce an
amount of discharge thereof.
In particular, in the future, when the C02 removal
regulation is s t a r t e d , there is a p o s s i b i l i t y t h a t the COz
removal device itself increases in size, and thus, it is
necessary to further reduce the amount of discharge.
[00061 As a technique t h a t prevents the release of the
amine absorbent, for example, a method of recovecing an
arnine compound accompanied by a C02-free flue gas, by
providing a p l u r a l i t y of stages of water washing sections
on a downstream side of a GOz absorption section of a COz
absorber of a Con removal device, and by bringing the C02-
free flue gas and washing water i n t o vapor-liquid contact
with each other has been suggested (Patent L i t e r a t u r e 2).
[0007] In addition, as another technique, a method of
recovering a basic amine compound in a decarbonator flue
gas that sprays a sulfuric acid from a sulfuric acid spray
device to a GO2-free flue gas discharged from a COP
absorber, converts an amine absorbent accompanied by the
flue gas into a basic amine compound sulfate, and collects
the basic amine compound sulfate has been suggested (Patent
Literature 3).
roo08 1 Furthermore, in the air pollution control system,
when a mist generation materlal that removes the mist
generation material being a generation source of mist
generated i n the absorber of the Cot recovery unlt is
contained i n t h e flue gas introduced into the C02 absorber
that absorbs C02 i n the C02 recovery unit, the C02 absorbent
is accompanied by the mist generation material. Therefore,
there is a problem that the amount of COz absorbent that
scatters to the outside of the system increases, and thus,
the countermeasures against the problem have been
considered (Patent Literature 4 ) .
Citation List
Patent Literature
[OOOS] Patent Literature 1: JP 3-193116 A
Patent Literature 2: JP 2002-126439 A
P a t e n t Literature 3: JP 10-33938 A
Patent Literature 4: WO 2011/152547 A
Sumnary
Technical Problem
[0010] However, in the above-described suggestions,
although the gaseous amine absorbent can be reduced in the
C02-free f l u e gas released from the COz absorber, there is
a risk of releasing the mist amine absorbent with the flue
gas. Accordingly, it is necessary to suppress this problem.
[ OOll] There is concern that the mist amine absorbent
released t o t h e outside of the system is converted into,
for example, nitrosamines, nitramine, aerosol or the l i k e
as a r e s u l t of reaction with NOx or the like in the
atmosphere a f t e r diffusion i n t o the atmosphere.
S [0012] Thus, t h e r e has been a desire for establishment
of an air pollution control system that can f u r t h e r
suppress the release of the amine compound accompanied by
t h e COz flue gas from the COz absorber.
lo013 1 In view of the above-described problems, an
10 object of the present invention is to provide an air
pollution control system that is capable of g r e a t l y
suppressing entrainment of the amine absorbent when
discharging the treated f l u e gas, from which COn is removed,
t o the outside of the system.
15 Solution t o Problem
[0014] According t o a first aspect of the present
invention i n order t o solve the above-mentioned p~oblems,
t h e r e is provided an air p o l l u t i o n control system including
a C02 recovery u n i t equipped with a CQZ absorber t h a t
20 removes GO2 i n a f l u e gas from a b o i l e r by an amine
absorbent, and an absorbent regenerator t h a t regenerates
the m i n e absorbent, wherein the CO2 absorber is equipped
with a C02 absorption u n i t that absorbs C02 in the flue gas
by the mine absorbent, and a water-repellent f i l t e r unit
25 t h a t is disposed on a gas flow downstream side of the C02
absorption unit and c o l l e c t s mist amine absorbent
accompanied by a GO2-free f l u e gas.
[0015] According to a second aspect of the present
invention, t h e r e is provided the air pollution control
30 system according t o the first aspect, wherein the waterrepellent
filter unit is equipped with a f i l t e r cylinder
having a gas introduction space i n t o which t h e COz-free
flue gas rising from the COz absorption unit is introduced,
and a plurality of water-repellent filters provided on a
side surface of the filter cylinder to allow the introduced
C02-free flue gas t o pass through the filters in a
direction orthogonal to a gas flow direction.
[0016] According to a third aspect of the present
invention, there is provided the air pollution control
system according to the second aspect, wherein a cleaning
unit for cleaning a gas in-flow surface o f the waterrepellent
filter is provided in the filter cylinder.
[0017] According to a fourth aspect of the present
invention, there is provided the air pollution control
system according to the second or third aspect, wherein a
collecting u n i t for collecting f a l l i n g water falling down
along the surface of the filter is provided on a lower end
side of the water-repellent filter.
[0018 I According t o a fifth aspect of the present
invention, there is provided the air pollution control
system according to the first aspect, wherein the waterrepellent
filter unit is integrally provided within the C02
absorber.
[0019] According t o a sixth aspect of the present
invention, there is provided the air pollution control
system according to the f i x s t aspect, Wherein the waterrepellent
filter u n i t i s provided separately from the C02
absorber.
[OOZO] According to a seventh aspect of the present
invention, there i s provided the air pollution control
system according t o the first aspect, wherein a water
cleaning unit is provided on one or both of an upstream
30 side and a downstream side of the gas flow of the waterrepellent
filter unit.
Advantageous Effects of Znvention
[002i] According to the air pollution control system of
the present i n v e n t i ~ n , by collecting t h e mist amine
accompanied by the COz-free flue gas using. a waterrepellent
filter, it is possible to'iurther reduce the
arnine concentration of the gas diffused to the atmosphere.
Brief Description of Drawings
[0022] FIG. 1 is a schematic diagram of an air pollution
control system provided with a COz recovery unit according
to a first embodiment.
FIG. 2 is a perspective view of a water-repellent
filter unit according to the first errtbodiment.
FIG. 3 is a longitudinal cross-sectional view of the
water-repellent filter unit according to the first
embodiment.
FIG. 4 is a cross-sectional view taken along a line XX
of FIG. 3.
FIG. 5 is a perspective view o f the water-repellent
filter according t o t h e f i r s t embodiment.
FIG. 6 is a cross-sectional view of another filter
cylinder according to the f i r s t embodiment.
FIG. 7 is a cross-sectional view of another f i l t e r
cylinder according to the first embodiment.
FIG. 8 is a cross-sectional view of another aspect
corresponding to FIG. 4.
FIG. 9 i s a cross-sectional view of another filter
cylinder according to the first embodiment.
FIG. 10 is a schematic diagram illustrating an
increase or decrease i n a gas passage area of the filter
depending on presence or absence of water-repellency.
FIG. 11 is a diagram illustrating an example of the
30' distribution of a mist particle diameter in an outlet gas
of a CO2 absorber.
FIG. 12 is a diagram illustrating a relation between a
gas passage flow velocity of t\e watex-repellent f i l t e r and
a f i l t e r pressure loss.
FIG. 13 i s a diagram illustrating a relation between a
SO3 concentration i n t h e gas and a f i l t e r pressure loss.
FIG, 14 is a schematic diagram of an a i r pollution
control system provided with a GO:! recovery u n i t according
t o a second embodiment.
FIG. 15 is a schernztic diagram of the a i r pollution
control system provided with a COZ recovery u n i t according
t o a t h i r d embod~ment.
FIG. 16 is a schematic diagram of an air pollution
control system provided with a COz recovery unit according
to a fourth embodiment.
Description of Embodiments
lo0231 Preferred embodiments of the present invention
w i l l be described i n detail with reference to the attached
drawings. Note t h a t the present invention is not intended
to be limited by these embodiments. When there is a
p l u r a l i t y of embodiments, t h e present invention also
includes an embodiment configured by combining the
embodiments.
[ F i r s t Embodiment]
[0024] FIG. 1 is a schematic diagram of an a i r pollution
control system provided w i t h a CO2 recovery u n i t according
to a first embodiment.
As illustrated in FIG. 1, an a i r poliution control
system 10A provided w i t h a CO:! recovery u n i t according t o
t h e present embodiment is a C02 recovery apparatus t h a t
removes C02 contained i n a coal combustion f l u e gas
(hereinafter, referred to as "flue gas") 11 discharged from,
for example, a coal combustion boiler. The a i r pollution
control system 10A has a cooling tower 20 that cools the
flue gas 11, a C02 recovery u n i t 30 that removes C02, and a
C02 compression apparatus 50 t h a t compresses C02 recovered
in the COz recovery unit 30 t o be C02 gas of high purity.
In the present embodiment, a first water cleaning u n i t
62B is provided between a COz absorption u n i t 34 and 8
water-repellent filter u n i t 36 in a Cop absorber 32.
In t h e f i r s t water cleaning u n i t 62A, t h e flue gas
comes i n t o gas-liquid contact with a cleaning water 63
supplied from the tower top side, and a p a r t of the
liquefied amine absorbent and the gaseous amine absorbent
accompanied by a COz-free flue gas 12A is removed p r i o r t o
10 i n t r c d u c t i o n i n t o the water-repellent f i l t e r u n i t 36.
In the present embodiment, on a gas flow downstream
side of the first water cleaning unit 62A, a demister 37
which is a glass fiber f i l t e r is installed.
[OOZS] The cooling tower 20 has a cooling part 20a that
15 injects cooling water 21 from the top side of the cooling
tower and brings t h e cooling w a t e r 21 i n t o countercurrent
contact with t h e f l u e gas 11 introduced from the lower p a r t .
Thereby, the gas temperature is reduced to a predetermined
temperature, and the cooling water 21 is reused by a
20 c i r c u l a t i o n l i n e L1l, a circulation pump Pll, and a cooler
22.
[00261 The COz recovery unit 30 that removes COa i n the
flue gas 11 after cooling has a C02 absorber ( h e r e i n a f t e r ,
also referred t o as an "absorber") 32 that removes COz by
25 bringing the flue gas 11 introduced from a l a t e r a l surface
side of t h e tower lower end into countercurrent contact
with the amine absorbent (lean solution) serving as a cOz
absorbent, and an absorbent regenerator (hereinafter, also
referred to as a "regenerator") 33 that, releases C02 from
30 the amine absorbent ( r i c h solution 31a) t h a t has a b s ~ r b e d
COz and regenerates t h e amine absorbent, and the C02
recovery u n i t 30 supplies a lean solution 31b from which
COz is removed by the absorbent regenerator 33 to the GOZ
absorber 32 side so as t o be used as the amine absorbent
(lean solution) again.
In FIG. 1, reference numeral L1 represents a rich
solution supply line, Lp represents a lean solution supply
5 line, L3 represents a reboiler circulation line, La
represents a gas discharge l i n e , L5 represents a condensed
water line, Ls represent$ a cleaning fluid circulation llne,
Ps represents a circulation pump, reference numeral 64
represents a cooler, and reference numeral 65 represents a
10 chimney t r a y .
[0027 1 The CO2 absorber 32 is provided with the COz
absorption unit 34 that absorbs C02 i n the flue gas 11 by
the amine absorbent (Lean solution 31b), and the waterrepellent
filter unit 36 that is provided on an upper
15 portion (gas flow downstream) side of the COz absorpkion
unit 34 and collects the mist amine absorbent accompanied
by the C02-free flue gas 12A.
[0028] PIG. 2 is a perspective view of the waterrepellent
filter unit according to the first embodiment,
20 FIG. 3 is a longitudinal cross-sectionai view of the waterrepellent
filter unit according to the first embodiment.
FIG. 4 is a cross-sectional view taken along a line X-X of
FIG. 3. FIG. 5 is z perspective view of the watarrepellent
filter according t o the first embodiment. FIGS.
25- 6 and 7 are cross-sectional views of another waterrepellent
filter unit according to the first embodiment.
As illustrated in these drawings, the water-repellent
filter unit 36 is provided with a filter cylinder 42 having
a gas introduction space S into which the Con-free flue gas
30 12A rising from the COz absorption unit 34 is introduced,
and a p l u r a l i t y of water-repellent filters 43 that is
provided on a side surface 42a o f the filter cylinder 42 to
allow the introduced C O 2 - f r e e flue gas 1ZA to pass in a
direction orthogonal to a gas f l o w d i r e c t i o n .
[0029] The filter cylinder 42 has the introduction space
S into which the CDz-free flue gas 12A is introduced from
at least one openings 41a that are provided in a f i l t e r
5 base 41 orthogonal to the gas flow direction of the COzfree
flue gas 12A rising from the COZ absorption unit 34.
The upper slde of the gas introduction space S is
closed by a ceiling surface 42c provided on a ceiling side
of the side surface 42a.
10 [0030) Furthermore, on the side surface 42a of the
filter cylinder 42, the plurality o f water-repellent
filters 43, through which the introduced C02-free flue gas
12A passes in a direction orthogonal to the gas rising
direction, is provided.
The water-repellent filter 43 is installed on a
plurality of openings 42b provided on the side surface 42a
of the filter cylinder 42 via a casing and a gasket.
[0031] The water-repellent filter 43 is disposed in a
multistage in a direction of height of the side surface 42a
20 of the filter cylinder 42 according to the flow velocity of
the gas to be treated, and is configured to remove the
amine mist in the C02-free flue gas 12A under the condition
of a predetermined pressure loss.
In FIG. 2, reference numeral W1 represents a width of
25 the. filter base 41, and L1 xepresents a length of the
f i l t e r base 41. The width and the length are the same as an
inner dimension of the COP absorber 32. Reference numeral
Wz represents a width of the filter cylinder 42, and Lz
represents a length of the f i l t e r base 41, The number of
30 installation of t h e filter cylinder 42 is not limited in
the present invention and can be appropriately changed in
consideration of the amount of gas to be treated, the
pressure loss, or the like.
COO321 As illustrated in FIG. 3, in t h e water-repellent
f i l t e r unit 36, the f i l t e r base 41, which is l n s t a l i e d
within the tower o f the COz absorber 32 to block the gas
flow of the COP-free flue gas 128, is installed. In the
5 filter base 41, the p l u r a l i t y of elongated rectangular
openings 4la is provided. Moreover, in the opening 41a,
the filter cylinders 42 having a rectangular cross-section
are disposed, respectively, and on both side surfaces 42a
of the filter cylinder 42, the plurality of water-repellent
10 filters 43 is installed.
[(I0331 The water-repellent filter 43 is disposed such
that its gas passage cross-section 1 s orthogonal to the
C02-free flue gas 12A.
Moreover, when the COz-free flue gas 12A passes
15 through the water-xepellent filter 43, the water-repellent
filter 43 collects the mist amine absorbent accompanied by
the gas, thereby further reducing the amine concentration
when a purified COz-free flue gas 12B is diffused t o the
atmosphere.
20 [(lo341 In addition, as illustrated i n FIG. 5, the waterrepellent
filter 43 may be configured to be equipped la a
f i l t e r frame 49. In such configuration, the waterrepellent
f i l t e r 43 is equipped i n the f i l t e r frame 49 i n
the a l t e r n a t e l y folded pleated shape. By weaving i n the
25 pleated shape several times, the filter area through which
the C02-free flue gas 12A passes i s improved.
lo0351 Here, it is preferred thac the gas flow velocity
(V1) of the COz-free flue gas 12A be approximately 2.5 m/s
la preferabke range is from 2.0 t o 3.0 m/s) at the flow
30 velocity of the gas rising from the C02 absorption unit 34,
and a cross-section of standard flow velocity (V2) when
passing through the water-repellent filter 43 be
approximately 0.3 to 1.2 m/s (a preferable range is from
0.5 to 0.8 m/s).
In addition, it is preferred that the pressure loss of
the water-repellent f i l t e r 43 be 30 t o 120 mmHaO (a
preferable range is from 40 t o 80 mmHZO).
S 100361 Thus, in the present invention, from the
viewpoint of facilitating the discharge ~f the c o l l e c t e d
mist, the water-repellent filter 43 is disposed so that its
gas passage cross-section is orthogonal to the C02-free
flue gas 12A (the water-repellent filter 43 itself is
10 v e r t i c a l l y disposed).
to0371 This is because, when the gas passzge crosssection
is horizontally disposed with respect t o the C02-
f r e e flue gas 12A (the water-repellent f i l t e r 43 itself is
horizontally disposed), the discharge of the collected mist
15 is poor, the pressure loss increases, and the amount of
process gas decreases, which is not preferable.
In addition, as in the present embodiment, i n addition
to a complete vertical disposition, the water-repellent
f i l t e r 43 may be obliquely disposed such that the opposite
20 side surfaces thereof have a tapered shape, for example, in
a roof shape.
[0038] In the pxesent embodiment, as illustrated in FIG.
6, as a collecting unit for collecting the falling water
t h a t f a l l s down along the surface of the filter, for
25 example, a trough 44 or the like may be provided on the
lower end side of the water-repellent filter 43.
[0039] Furthermore, in the present esnbodirnent, as
illustrated in FIG. 7, a cleaning u n i t (for example, a
cleaning spray, and a cleaning nozzle) 47 for cleaning the
30 gas in-flow surface of the water-repellent f i l t e r 43 by a
cleaning water 46 is i n s t a l l e d in the filter cylinder 42.
The d u s t adhering to the filter surface may be removed by a
spraying water 46a sprayed from the cleaning unit 47. Here,
FIG. 8 is a diagram corresponding to FIG. 4, and
illustrates a spray region state of the spraying water 46a
within the space.
[0040] Furthermore, in the present embodiment, as
illustrated in FIG. 9, as a shape of the filter cylinder 42
in which the water-repellent filter 43 is provided, a
stepped shape may be used.
In the embodiment illustrated in FIG. 9, a width A of
the opening 41a of the gas introduction side is wider than
a width B of the top o f the filter cylinder 42, the side
surface 42a has a stepped shape, and the interval between
the side surfaces facing each other is narrowed as the COzfree
flue gas 12A rises.
By changing the gas in-flow space on the gas
introduction side of the bottom of the filter cylinder 42,
it is possible to allow the gas to more uniformly flow in
the f i l t e r s of each stage.
[0041] Here, it is essential in the present invention
that the filter used in the water-repellent filter unit 36
have water repellency.
[0042] FIG. 10 is a schematic diagram i l l u s t r a t i n g an
increase or decrease in a gas passage area depending on
presence or absence of water repellency.
In FIG, 10, the Left side is the case of using a
water-repellent filter, and the right side is the case of
using a water-resistant filter. FIG. 10 i l l u s t r a t e s a
cross-section of the filter, and in the figure, reference
numeral t represents a thickness of the filter, and
reference numeral 48 represents a water f i l m . Here, in FIG,
10, the right side of the filter is a space interior side
of the filter cylinder 42, and the left side of the filter
is an exterior.
As illustrated on the r i g h t side of FIG. 10, in the
case of the water-resistant filter. Accordingly, a
material thereof is glass wool having a low w a t e ~
repellency, the moisture accompanied by the GO2-free f l u e
gas 12A is held on the surface of the filter to become a
5 water film 48 to block the gap of the filter passage gas
part and as a result, a pressure loss increases. Thus, the
water-resistant filter is not preferable.
[0043] In contrast, as in the present invention, in the
case of the water-repellent filter iliustrated on the left
10 side, since the filter has water repellency, the moisture
acconpanied by the Con-free flue gas 12A is not held on the
f i l t e r surface and f a l l s downward, and the gap of the
filter passage gas part remains. Consequently, a decrease
in the gas passage area is small, the pressure loss
15 increases but is within a tolerance, and thus, the watexrepellent
filter is preferable.
Therefore, in order to obtain this effect, it is
preferred that the filter be vertically disposed rather
than obliquely disposed.
20 [0044] Here, as the water-repellent filter 43, it is
desirable to use a polytetrafluoroethylene (hereinafter,
referred to as "PTFE") porous film having a high water
repellency.
Furthennore, an average pore diameter of the porous
25 film is about 0.01 t o 10.0 pm (preferably, about 0.1 to 0.5
P) -
In addition, as the water-repellent filter 43, it is
desirable that a contact angle to water be 60' or more
(preferably, 90° or more) .
30 COO451 This is because the average particle size of the
mist to be collected in the C02 recovery unit is
approximately 1 ,p.m. In p a r t i c u l a r , when SO3 coexists in
the flue gas introduced into the C02 recovery u n i t , a
phenomenon of an increase in the diffused amine is observed
with an increase in the fine mist having the p a r t i c l e size
of 1 p or less (see the above-described Patent Literature
5 4 ) .
Therefore, in order to increase the collection
efficiency of the mist having an average particle diameter
or less, the average pore size of the porous film is
preferably about 0 . 1 t o 0.5 p.
10 [0046] In addition, other than a filter made of PTFE,
for example, it is preferable to use a water-repellent
filter obtained by coating PTFE to polyethylene,
polypropylene, and a glass wool, and another waterr
e p e l l e n t filter containing a fluorine resin. The filter
15 may have a structure that is reinforced i n combination with
another low pressure loss porous material (a reinforcement
m a t e r i a l ) .
[0047] FIG. 11 is a diagram illustrating an example of
the distribution of the mist particle diameter in the
20 outlet gas of the COZ absorber. As i l l u s t r a t e d i n FIG. 11,
it is understood t h a t the m i s t present in the COz-free f i u e
gas i s present as a mist state having an average particle
diameter of 1 p.
Therefore, by aLLowing the C02-free flue gas 12A
25 containing the mist arnine having the particle size to pass
through the water-repellent filter, it is possible to
collect the accompanied mist arnine, thereby suppressing the
reiease to the outside.
[go481 FIG. 12 is a diagram illustrating a relation
30 between a gas passage flow velocity of the water-repellent
f i l t e r and the filter pressure loss. The relation between
t h e gas passage flow velocity of the water-repellent filter
43 and the filter pressure 'loss was obtained using a gas
Having the SO3 c o n c e n t r a t i o n of 3 ppm.
As i l l u s t r a t e d i n FIG. 12, when the gas passage flow
velocity increases, the pressure l o s s also gradually
5 increases accordingly, but a s i g n i f i c a n t pressure change
was not observed.
Therefore, the gas passage flow velocity of t h e f i l t e r
unit may be determined i n consideration of t h e amount o f
gas to be treated, and t h e pressure l o s s .
10 [0049] FIG. 13 is a diagram illustrating a relation
between t h e SO3 concentration i n the gas and the filter
pressure loss.
Since the gas in the C02 absorber 32 is a moisturesaturated
gas, it was observed whether there was any
15 pressure f l u c t u a t i o n in the filter according to the change
of the SOs concentration contained i n t h e gas. Here, t h e
gas flow velocity was 0.35 m/m.
As i l l u s t r a t e d i n FIG. 13, it was observed that there
was no significant fluctuation i n the pressure loss by the
20 filter passage even when the SO3 concentration in t h e gas
changed (0.2 to 3 ppm) .
It is assued that there is no s i g n i f i c a n t fluctuation
in the pressure loss as a result of the discharge due t o
the natural drop of the collected m i s t f r a c t i o n along the
25 water-repellent f i l t e r surface.
[OOSO] Here, i n the above-described absorber 32, the
flue gas 11 containing COz introduced from the tower bottom
side comes i n t o countercurrent contact with t h e amine
absorbent based on, for example, alkanoiamine, i n the COz
30 absorption u n i t 34, and GO2 i n t h e f l u e gas 11 is absorbed
to t h e mine absorbent side by the chemical reaction (R -
NHz -t Hz0 1- CO;, -+ R - NH3HCO3) .
[00511 Then, t h e C02-free f l u e gas 12A after removal of
COz rises to the water-repellent filter unit 36 side after
passing through the demister 37, and the mist amine
absorbent is removed by the water-repellent f i l t e r unit 36.
In the demister 37, it is possible to collect the mist
5 having the large particle diameter generated i n the filling
unit or the liquid supply unit of the absorber, but for
example, the collection characterrstics of the fine mist
caused by SO3 are low. Meanwhile, since the waterrepellent
filter unit 36 is able to collect the fine mist,
10 the amine concentration diffused to the atmosphere is
further reduced compared to the related art when the
purified C02-free flue gas 12B is discharged to the outside
from the tower t ~ opf the COZ absorber 32. In the present
embodiment, on the tower top side of the downstream of the
15 water-repellent filter unit 36, a wire mesh demister 38 is
provided to further collect the mist components.
This aims to reduce the concentration of the diffused
amine by collecting the mist having the large particle
diameter generated by re-scattering of a part of the mist
20 collected in the water-repellent filter 43.
LO0521 The rich solution 31a after absorbing COz is
increased in pressure by a rich solvent pump P1 interposed
i n the rich solution supply line L1, is heated by the lean
solution 31b regenerated in the absorbent regenerator 33 in
25 a rich-lean solution heat exchanger 39, and is supplied to
the tower top srde of the absorbent regenerator 33.
[0053] The rich solution 31a released to the tower
interior from a tower top 33a side of the regenerator 33
releases most COZ by heating due to water vapor from the
30 tower bottom of the reg-enerator 33. The introduced arnine
absorbent (rich solution 31a) becomes the lean solution
( a m i r l e absorbent) obtained by removing almost all COz, by
th.e t i m e of flowing down to the tower bottom of t h e
regenerator 33. A part of the lean solution 31b is heated
by saturated water vapor 52 i n a regenerative heater 51
interposed in the reboiler circulation line L3. The
saturated water vapor 52 after heating becomes condensed
5 water 53.
[0054 1 Meanwhiie, COi gas 54, which is accompanied by
the water vapor released within the tower, is discharged to
the outside from the tower top 33a of the regenerator 33.
Then, the C02 gas 54 accompanied by the water vapor is
10 derived by the gas discharge line Lq, the water vapor is
condensed by a condenser 55 interposed in the gas discharge
l i n e Ls, and the condensed water is separated in a
separation drum 56. The CO2 gas from which the moisture i s
separated is released to the outside of the system, and is
15 subjected to post-treatment such as compression and
recovery, using a p l u r a l i t y of C02 compressors 57
interposed in the gas discharge l i n e La. A cooler 58 is
interposed between the plurality of C02 compressors 57 to
cool the compressed gas.
A compressed C02 gas 59 subjected to the compression
and recovery is stored, for example, in the ground or used
as a high purity COz-
[OOSS] The condensed water separated in the separation
drum 56 is supplied to the top of the absorbent regenerator
25 33 by a condensed water circulation pump P3 interposed in
the condensed water l i n e Lg.
roo561 The regenerated amine absorbent (lean solution)
is sent to the C02 absorber 32 side by the lean solution
pump P2 via the lean solution supply line L2 and is heat-
30 exchanged in the rich-lean heat exchanger 39. Subsequently,
the regenerated amine absorbent is cooled to a
predetermined temperature in a cooler 61, and is circulated
and used as t h e amine absorbent (lean solution 31b).
Tnerefoxe, the arnine absorbent forms a closed path
that circulates through the C02 absorber 32 and the
absorption solution regenerator 33, and is reused i n the
Can absorption unit 34 of the CO2 absorber 32. Note t h a t
5 an amine absorbent 31 is also supplied by a supply line
(not illustrated) zf necessary, and the thermostable salt
i n t h e amine absorbent is removed by a reclaimer (not
i l l u s t r a t e d ) i f necessary.
[0057] In the present embodiment, the water-repellent
10 filter unit 36 having the water-repellent filters 43 is
installed inside the C02 absorber 32 forming t h e COn
recovery unit 30. Sy introducing the C02-free flue gas 12A
into the water-repellent filter unit 36 and causing the gas
to pass through the water-repellent filters 43, it is
possible to collect the mist amine accompanied by the COzfree
flue gas. As a result, even when t h e purified C02-
free flue gas 125 is released to the outside ~f the
absorber 32, it is possible t o f u r t h e r reduce the amine
concentration diffused to the atmosphere compared to the
.dernisters such as the conventional glass f i l t e r .
[0058] I n addition, in the present embodiment, s~nce a
part of the amine absorbent and the gaseous amine absorbent
is removed in the first water cleaning unit 62B prior to
introduction into the water-repellent filter unit 36, load
to the water-repellent filter 'unit 36 is reduced and the
c o l l e c t i o n efficiency of the mist amine is also improved.
[Second Embodiment]
[OOSSJ Next, an air pollution control system provided
with a CO2 recovery unit according to a second embodiment
of the present invention will be descxibed. Mote that the
components same as those i n t h e first embodiment are
denoted by the same reference numerals, and the d e s c r i p t i o n
thereof w i l l not be provided.
FIG. 14 is a schematic diagram of the air pollution
c o n t r o l system provided wlth the COz recovery unit
according t o the second embodiment of t h e present invention.
As i l l u s t r a t e d i n FIG. 1 4 , an air p o l l u t i o n control
5 system 108 equipped with a C02 recovery u n i t 30 according
t o t h e present embodiment is provided with a second water
cleaning u n i t 62B, on the downstream s i d e of a waterrepellent
filter unit 36 i n the C02 absorber 32 of t h e
first embodiment.
10 [00601 In the second water cleaning unit 625 of the
present embodiment, a f l u e gas comes into gas-liquid
contact with cleaning water 63 supplied from the tower top
side, t h e liquefied amine absorbent and the gaseous arnine
absorbent accompanied by C02-free flue gas 12A are removed
15 a f t e r being removed in the water-repellent filter unit 36.
Reference numeral P6 represents a c i r c u l a t i o n pump,
reference numeral 66 represents a cooler, and L7 represents
a cleaning f l u i d circulation line.
I n s t a l l a t i o n of the second water cleaning unit 62B on
20 the downstream side of the water-repellent f i l t e r unit 36
allows further reduction of the diffused amine
concentration, compared to the first embodiment, by
collecting the re-scattered mist from a water-repellent
filter 43 and the re-scattered amine components evaporated
25 from t h e mist collected i n the water-repellent f i l t e r 43.
[Third Embodiment]
[OOSl] Next, an air pollution control system provided
with a COz recovery unit according to a third embodiment of
the p r e s e n t invention w i l l be described. Note that the
30 components same as those in the first and second
embodiments are denoted by the same reference numerals, and
the d e s c r i p t i o n thereof w i l l not be provided.
FIG-' 15 is a schematic diagram of the air pollution
control system provided with t h e COz recovery unit
according t o the third embodiment of the present invention.
As illustrated in FIG. 15, an air pollution control
system 10C equipped with a C02 recovery unit 30 according
5 to the present embodiment is provided with a second water
cleaning unit 62B, on the downstream side of the gas flow
of the water-repellent filter unit 36 in the COz absorber
32 of the Eirst embodiment,
In the present embodiment, it is possible to f u r t h e r
10 reduce the diffused amine concentration compared to the
Eirst embodiment, by collecting t n e re-scattered mist from
a water-repellent filter 43 and the amine components
generated by evaporation from the m i s t collected by the
water-repellent filter 43 in the second water cleaning unit
15 62B.
[Fourth Embodiment]
[ 00 621 Next, an air pollution control system provided
with a C02 recovery unit according to a fourth embodiment
of the present invention will be descxibed. Note that t h e
20 components same as those in the first to third embodiments
are denoted by the same reference numerals, and the
description thereof will not be provided.
FIG. 16 is a schematic diagram of the air pollution
control system equipped with the C02 recovery unit
2.5 according to the fourth embodiment of the pxesent invention.
As illustrated in FIG. 16, in an air pollution control
system 10D equipped with a COz recovery unit 30 according
to the present embodiment, a water-repellent filter unit 36
and a second water cleaning unit 62B installed in the Con
30 absorber 32 of the second embodiment 2 are provided i n a
gas cleaning tower 70, which is separately placed.
This configuration avoids an increase in the vertical
placement of the COZ absorber 32.
Furthermore, by using the conventional C02 absorber 32,
and by separately additionally providing the gas cleaning
tower 70 on which the water-repellent filter unit 36 and
the second water cleaning unit 6ZB of the present
5 embodiment are disposed, it is possible to further reduce
the diffused amine concentration without a large
modification.
Note t h a t , even in the first, second, and third
embodiments, the water-repellent filter unit 36 may be
10 provided in a gas cleaning tower 70 i n s t a l l e d outside the
COz absorber 32.
[0063] [Example]
Hereinafter, Examples illustrating the effects of the
present invention will be described. However, the present
15 invention is not limited thereto.
As Example 1, as a mist removal unit, a glass fiber
filter (GS) was i n s t a l l e d i n a first stage, the waterrepellent
filter unit 36 of the water-repellent filter was
i n s t a l l e d i n a second stage of the downstream side of the
20 gas flow, and a wire mesh demister (MD) was instailed i n a
third stage of the downstream side of the gas flow.
As Example 2, as a mist removal unit, a glass fiber
demister (GD) was installed i n the first stage, the waterrepellent
filter unit 36 of the water-repellent filter was
25 installed i n the second stage of the downstream side of the
gas flow, and a glass fiber demister (GD) was i n s t a l l e d in
the third stage of the downstream side of the gas flow.
[00641 As Comparative Example 1, as a m i s t removal u n i t ,
the glass fiber demister (GD) was i n s t a l l e d i n the first
30 stage, and the wire mesh demister (MD) was installed in the
second stage of the downstream side of the gas flow.
As Comparative' Example 2, as the mist removal unit,
the glass f i b e r demister (GD) was installed in the first
stage, the wire mesh demister (MD) was installed in the
second stage of the downstream side of the gds flow, and
the glass fiber demister (GD) was installed i n the third
stage of the downstream side of the gas flow.
As Comparative Example 3, as the mist removal unit,
the glass f i b e r demister (GD) was installed in the first
stage, a water-resistant filter of the water-resistant
filter was installed in the second stage of the downstream
side of t h e gas flow, and the wire mesh demister (MD) was
10 i n s t a l l e d in the third stage of the downstream s i d e of the
gas flaw.
[do651 The diffused amine concentration was measured
under t h e conditions where the SO3 mist concentration in
the gas was set t o 1 ppm and 3 ppm. The results are
15 illustrated in Table 1.
Table 1
GD: glass f i b e r demister
MD: wire mesh demister
Water-repellent filter
Water-resistant filter
LO0671 ' As illustrated i n Table 1, in Comparative Example
1 of t h e related art, when the SO3 mist concentration was 1
ppm, t h e amine concentration of absorber outlet was 20 ppm.
In Comparative Example 1 of the &elated art, when the
SO3 mist concentration was 3 pprn, the amine concentration
5 of absorber outlet was 37 ppm.
to068 J As in Comparative Example 2, when the SO, mist
concentration was 1 ppm, even In a case where the glass
fiber demister (GD) was i n s t a l l e d in the third stage, the
amine concentration of the absorber outlet was lowered only
10 to 2 pprn.
Furthermore, as in Comparative Example 2, when the SO3
mist concentration was 3 ppm, even i n a case where the
glass fiber demister (GD) was installed in the third stage,
the amine concentration of the absorber outlet was lowered
15 only to 7 ppm.
[0069] In contrast, as in Example 1, in a case where the
water-repellent f i l t e r was installed in the second stage
and the w i r e mesh demister (MD) was installed i n the third
stage, when the SO3 mist concentration was 1 ppm, the mine
20 concentration of the absorber o u t l e t was significantly
lowered to 0.7 ppm. Furthermore, when the SO3 mist
concentration was 3 pprn, t h e arnine concentration of the
absorber o u t l e t was significantly lowered to 1.0 ppm.
[00701 A s i n Example 2, i n a case where the water-
25 repellent filter was installed in t h e second stage and the
glass fiber demister (GD) was installed in the third stage,
when the SO3 mist concentration was 1 ppm, the arnine
concentration of the absorber outlet was further lowered t o
0.15 pprn. Furthermore, when the SO3 mist concentration was
3 ppm, the amine concentration of the absorber outlet was
significantly lowered to 0.3 ppm.
[0071] As i n Comparative Example 3, i n a case where the
water-resistant filter was installed, the filter pressure
loss increased, and the measurement was not possible.
[0072] Thus, when using the water-repellent filter as in
the present invention, it was observed that it is possible
to collect the mist amine accompanied by the C02 flue gas
and to further reduce the concentration of amine diffused to
the atmosphere.
We C l a i m :
1. An air pollution control system comprising a C02
recovery unit equipped with a C02 absorber that removes C02
in a flue gas from a boiler by an amine absorbent, and an
absorbent regenerator that regenerates the amine absorbent,
Wherein the C02 absorber is equipped with a C02
absorption unit that absorbs co2 in the flue gas by the
amine absorbent, and
a water-repellent filter unit that is disposed on a gas
flow downstream side of the C02 absorption unit and collects
mist amine absorbent accompanied by a C02 -free flue gas.
2. The air pollution control system according to claim 1,
Wherein the water-repellent filter unit is equipped
with a filter cylinder having a gas introduction space into
which the C02-free flue gas rising from the C02 absorption
unit is introduced, and
A plurality of water-repellent filters provided on a
side surface of the filter cylinder to allow the introduced
co2-free flue gas to pass through the filters in a direction
orthogonal to a gas flow direction.
3. The air pollution control system according to claim 2,
wherein a cleaning unit for cleaning a gas in-flow
surface of the water-repellent filter is provided in the
filter cylinder.
4. The air pollution control system according to claim 2
or 3,
Wherein a collecting unit for collecting falling water
falling down along the surface of the filter is provided on
a lower end side of the water-repellent filter.
5. The air pollution control system according to claim 1,
wherein the water-repellent filter unit is integrally
provided within the C02 absorber.
6. The air pollution control system according to claim l,
wherein the water-repellent filter unit is provided
separately from the COz absorber.
7. The air pollution control system according to claim 1,
wherein a water cleaning unit is provided on one or
both of an upstream side and a downstream side of the gas
flow of the water-repellent filter unit.