DEVICE'FOR RECOVERING RESIDUAL HEAT FROM EXHAUST GAS
BACKGROUND OF TVE-INVENTION
Field of the Invention
The present invention relates to a device for
recovering residual heat from exhaust gas. Particularly,
t
the present invention relates to a device for recovering
<-%
residual heat from exhaust gas that includes a dry
I economizer which heats to-be-heated water by utilizing
I sensible heat of the exhaust gas, the dry economizer being
provided in a duct extending to a funnel through which the
exhaust gas is emitted to atmosphere; and a condensation
economizer which heats to-be-heated water by utilizing
latent heat of condensation of the exhaust gas,
$he
condensation economizer being provided on the downstream
t
side of the dry economizer. I
Description of the Related Art I
In related art, in a duct through which the exhaust
I
from a boiler is circulated, an economizer is provided, ,
which heats a boiler water supply (to-be-heated water)
using residual heat of the exhaust gas. The economizer
recovers the residual heat'of the exhaust gas by performing
a heat exchange with the boiler water supply. Particularly,
a condensation economizer has a configuration that is also
able to recover latent heat discharged when vapor in the
exhaust gas is lcondensed and becomes water. Thus, by using
the condensatio? economizer together with a dry economizer
that mainly recovers the sensible heat of the exhaust gas,
the residual heat is able to be further recovered, which is
capable of improving heating efficiency of the boiler.
[0003]
t
As the device for recovering residual heat from
--*
exhaust gas, for example, Patent Document 1 discloses a
boiler in which, in a duct through which the exhaust gas of
a downward flow is circulated, a dry economizer, an air
preheater, and a condensation economizer are sequentially
disposed in series. In Patent Document 1, residual
quantity of heat contained in the exhaust gas passed
through the dry economizer is able to be recovered by a a ,
tubular air preheater, and the condensation economizer.
8
Furthermore, in a water pipe group that is a major 1 '
component of the condensation economizer, condensation is b
promoted, and a slightly wet portion partially exists. 1
Furthermore, Patent Document 2 discloses a
condensation economizer in which a sensible heat transfer
area and a condensation heat transfer area are alternately
provided in a duct through which the exhaust gas of
downstream flow is circulated. Specifically, in Patent
I
I Document 2,-a fin tube, through which a boiler water supply
I
is circulated, is arranged in multiple stages, a front
stage of the multi-stage fin tube is set to a sensible heat
transfer area of a high temperature, a middle stage thereof
is set to a condensation heat transfer area, and a rear
stage thereof is set to a sensible heat transfer area of a
~ low temperature, whereby the sensible heat and the latent
heat of the exhaust gas are recovered in each heat transfer
area.
@
Patent Document 1: Japanese Patent Application Laid-
Open No. 11-118104
Patent Document 2: Japanese Patent Application Laid-
Open No. 2001-208302
[0006]
However, since the condensation economizer of the
boiler of Patent Document 1 is disposed in the d5ct through
which the exhaust gas of downstream flow is circulated and
8
a partial wet portion is generated in the water pipe group
b
by the condensation of vapor in the exhaust gas, the water
pipe group has a wet area and a dry area. The wet area and
the dry area are changed in position along with a change in.
boiler load. That is, when the boiler load is changed, the
1. temperature of the exhaust gas passing through the
' condensation economizer is changed. Thus, a position,
where the exhaust gas amounts 'to a condensation temperature,
is changed, a boundary p,osition between the wet area and
the -dry are2:is changed. Accordingly, since the exhaust
gas flows from the upside, the dry area is generated in the
upper part of the condensation economizer, the wet area is
generated in tde lower part thereof, and a zone, where the
drying and the vekting are repeated, is generated in the
middle part thereof. In the middle part, the water pipe
I
group repeats the cooling and the heating, and thus there
is a possibility that stress corrosion cracking (SCC) may
occur in the water pipe.
9
I Furthermore, in Patent Document 2, since the
I sensible heat transfer area and the condensation heat
transfer area are alternately provided, the structure is
complicated and the apparatus increases in size. In
addition, since it is feared that the position of the
condensation heat transfer area is changed due to a change
in boiler load, similarly to Patent Document 1, q zone is
generated where 8 the drying and the wetting are repeated,
whereby there is a possibility of the stress corrosion
cracking being generated.
[0008]
The present inventfon was made in view of the above
circumstances, and an object thereof is to provide a device
I
fQk recovering residual heat from exhaust gas that has a , ,
simple structure and is able to prevent the drying and
wetting cycle in the condensat'ion economizer.
SUMMARY OF THE INVENTION
[0009]
According to an embodiment of the present invention,
the device for kecovering residual heat from exhaust gas
comprises a dry,economizer which heats to-be-heated water
by utilizing sensible heat of the exhaust gas, the dry
economizer being provided in a duct extending to a funnel
through which the exhaust gas is emitted to atmosphere; and
a condensation economizer which heats to-be-heated water by
t
utilizing latent heat of condensation of the exhaust gas,
c.r;t
the condensation economizer being provided on the
downstream side of the dry economizer, wherein the duct
comprises an upstream duct in which the dry economizer is
provided and a downstream duct connected to the upstream
duct and directing the exhaust gas to flow upward, and
wherein the condensation economizer is arranged in the
downstream duct so that temperature of the exhausIt gas
amounts to condpe nsation temperature at a vicinity of an
upper part of the condensation economizer. I '
[ 0 0 10 ] b
,
In the device for recovering residual heat from 1
i
exhaust gas, the condensation economizer is provided in a .
downstream duct that directs the exhaust gas to flow upward, I
an3 the device is configured so that temperature of the
' ,
exhaust gas amounts to condensation temperature at a
vicinity of the upper part ofthe condensation economizer.
Thus, vapor in the exhaqst gas is condensed in the vicinity
of the upper:part of the condensation economizer, and
1 becomes a drain (condensed water). The generated drain
falls down from vicinity of the upper part of the
condensation edonomizer and comes into contact with the
water pipe group constituting the condensation economizer,
and thus, the outer wall of the' water pipe is kept in a wet
state from the upper part to the lower part. For this
reason, the drying and wetting cycle is able to be
prevented in the water pipe group in the condensation
4
economizer, which is able to prevent the stress corrosion
'e
cracking.
Furthermore, when falling down from the vicinity
of the upper part of the condensation economizer, since the
generated drain comes into contact with the water pipe
group and falls down so as to face the exhaust gas of the
upward flow, it is possible to increase partial pressure of
the vapor in the exhaust gas flowing in the cond~sation,
economizer. Fo#r this reason, the condensation amount of
the condensation economizer is increased, the condensatio;.
b
efficiency rises, and the residual heat recovery rate of
!
the exhaust gas rises. L
In, addition, the devicesfor recovering residual I
heAt from exhaust gas has a configuration in which the t j
upstream duct is provided with the dry economizer and the
condensation economizer is in the downstream duct
which is connected to the upstream duct and directs the
exhaust gas-t.o flow upward. Thus, the device is able to be
simply configured.
~referabl'~t,h e device for recovering residual heat
further comprises:-a white-smoke detector which detects
white smoke of the exhaust gas Gmitted to the atmosphere
through the funnel; a heater which heats the exhaust gas on
the downstream side of the condensation economizer in a
flow direction of the exhaust gas by heat transfer from the
t
exhaust gas in the upstream duct to the downstream side of - the condensation economizer; and a heating controller which
controls heating condition of the heater based on detection
result of the white-smoke detector.
[0013]
Generally, since, in the exhaust gas, vapor in the
exhaust gas is cooled and changed to water droplets, when
the exhaust gas is discharged from the funnel to &he
atmosphere as i8t is, white smoke is easily generated. For
that reason, in the device for recovering residual heat I
b
from exhaust gas, the exhaust gas heat of the upstream duct
is transferred to the downstream side of the exhaust gas 1
I
flow of the condensation economizer, and the exhaust gas of*
the downst'ream side of the exhaust gas flow of the
I
i
condensation economizer is heated. As a result, it is
' possible to raise the temperature of the exhaust gas of the
downstream side of the exhaust gas flow of the condensation
economizer to lower the .relative humidity of the gas after
the -mixture-,. which is able to suppress the occurrence of
white smoke.
Furthermore, since it is possible to control the
heating state df the heater based on the detection result
of the white-smoke detector that detects white smoke of the
exhaust gas emitted from the finnel to the atmosphere, the
temperature of the exhaust gas is able to be adjusted so
that the white smoke is not generated.
In the aforementioned case, the heater may be a
'-L5
gas heater which comprises: a heat recovery section at
which residual heat of the exhaust gas is recovered by a
heat exchanger plate on the downstream side of the dry
economizer in the exhaust gas flow; and a reheating section
at which the exhaust gas is reheated on the downstream side
of the condensation economizer by the residual heat having
been recovered by means of the heat exchanger plqte at the
heat recovery section, the gas heater rotating the heat
t '
exchanger plate so as to be placed in the heat recovery
b
section and the reheating section alternately, and the
1
heating controller may increase the rotational speed of the ,
heat exchanger plate with'the increase in concentration of '
the white smoke based on the detection result of the white-
smoke detector. ' [0015]
As a result, since the exhaust gas heat of the
upstream duct is able to. bk transferred to the downstream
side of the-exhaust gas flow of the condensation economizer
and the exhaust gas is able to be reheated on the
downstream side of the exhaust gas flow of the condensation
economizer, an bccurrence of white smoke is able to be
suppressed. Fu~thermore, since the exhaust gas heat of the
upstream duct to be transferred'to the downstream side of
the exhaust gas flow of the condensation economizer is able
to be obtained by being recovered in the heat recovery
section, the temperature of the exhaust gas of the
4
downstream side of the exhaust gas flow of the dry
Crdr
economizer is able to be lowered. Thus, the temperature of
the exhaust gas is able to be lowered before flowing into
the condensation economizer, whereby the exhaust gas is
easily condensed by the condensation economizer.
Furthermore, since the rotational speed of the gas
heater is raised with the increase in concentration of the
white smoke based on the detection result of the phite- ,
smoke detector,,the temperature of the exhaust gas is able
I ' to be effectively regulated so that white smoke is not
b
generated.
[0016]
Alternatively, th'e heater may comprise: a bypass
channel th'rough which the upstream duct is in communication
I
with the downstream duct so that a portion of the exhaust ,
j
gas in the upstream duct flows into the downstream side of
the condensation economizer; and a damper which adjusts
flow rate of the portion of the exhaust gas flowing in the
bypass channel, and the heating controller may increase the
opening amount of the damper with the increase in
condensation economizer.
Thus, since water is sprayed toward the exhaust
gas flowing in the-condensation economizer, it is possible
to further improve the vapor paitial pressure in the
exhaust gas flowing in the condensation economizer. For
this reason, the condensation amount in the condensation
economizer is increased and the condensation efficiency is
4
raised, whereby the residual heat recovery rate of the
.-j,
exhaust is raised.
Furthermore, since the temperature of water to be
sprayed into the exhaust gas by the spray nozzle is set to
a temperature between the inlet temperature and the outlet
I temperature of the to-be-heated water to the condensation
economizer, a decline in condensation efficiency is able to
I
be prevented without rapidly cooling the exhaust gas. j
Further, it is preferable that the to-be-heated I '
water flows in the dry economizer and the condensation
L
,
economizer in a direction that is opposite to a direction I
I
of the exhaust gas.
Thus, since the flow dire,ction of the to-be-heated
t
1 '
water flowing in the dry economizer and the condensation
' economizer is provided so as to face the flow direction of
the exhaust gas, the heat reco'very efficiency is able to be
improved.
In the present invention, t.he condensation
economizer is provided in a downstream duct that directs
the exhaust gad to flow.upward, and the device is
configured so that temperature of the exhaust gas amounts
i to condensation temperature at a vicinity of the upper part
I of the condensation economizer. Thus, vapor in the exhaust
gas is condensed in the vicinity of the upper part of the
condensation economizer, and becomes a drain. The
?
generated drain falls down from vicinity of the upper part
lr5
of the condensation economizer and comes into contact with
the water pipe group constituting the condensation
I economizer, and thus, the outer wall of the water pipe is
I kept in a wet state from the upper part to the lower part.
For this reason, the drying and wetting cycle is able to be
prevented in the water pipe group in the condensation
economizer, which is able to prevent the stress qorrosion
cracking.
8
Furthermore, when falling down from the vicinity
C
of the upper part of the condensation economizer, since the
1
1
generated drain comes into contact with the water pipe
group and falls down so a's to face the exhaust gas of the
upward flow, it is possible to increase partial pressure of
I
thb vapor in the exhaust gas flowing in the condensation , ,,
economizer. For this reason, the condensation amount in
the condensation economizer is' increased, the condensation
efficiency rises, and th,e residual heat recovery rate of
the -exhaust-g as rises.
[0021]
' In addition, the device for recovering residual
heat from exhadst gas has a configuration in which the
upstream duct ig provided with the dry economizer and the
condensation economizer is prov'ided in the downstream duct
which is connected to the upstream duct and directs the
exhaust gas to flow upward. Thus, the device is able to be
simply configured.
-*
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic configuration diagram that
illustrates an example of the device for recovering
residual heat from exhaust gas according to a first
embodiment.
Figs. 2A to 2C are schematic diagrams thatl illustrate installation examples of a spray nozzle.
8
Figs. 3A and 3B are schematic configuration diagram&
b
that illustrate modified examples of the device for
f recovering residual heat from exhaust gas according to the ,
first embodiment. ,
Fig; 4 is a schematic con,figuration diagram that
illustrates an example of a device for recovering residual, ,
heat from exhaust gas according to a second embodiment.
Fig. 5 is a schematic configuration diagram that
illustrates an example of a device for recovering residual
heat- from exhaust gas according to a third embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinaft,er., preferred embodiments of the present
invention will be described in 'detail with reference to the
drawings. However, sizes, materials, shapes, relative
dispositions or the like of components described in the
, .
present embodiment do not purport to limit the scope of the
t
present invention thereto but are mere description examples
unless specifically described.
I First Embodiment
I Fig. 1 is a schematic configuration diagram that
illustrates an example of the device for recovering
residual heat from exhaust gas according to a first
embodiment of the present invention. Fig. 2 is 4 schematic
diagram that illustrates an installation example of a spray
I
nozzle provided at the vicinity of a condensation
economizer.
The device 1 for recovering residual heat from
exhaust gas according to the present invention is provided
I
inb;'dau ct connected to a funnel 10 that discharges the
' exhaust gas from a boiler to the atmosphere. As shown in
Fig. 1, the device 1 for recov'ering residual heat from
exhaust gas mainly include-s a dry economizer 2 and a
condensation economizer 4.
The dry economizer 2 and the condensation
economi'zer 4 include a water pipe through which the to-beheated
heated water (a',boilerw ater) is circulated. A material of
the water pipe refera ably uses SUS316L added with
molybdenum in austenitic stainl&ss steel from the viewpoint
improving a corrosion resistance.
The dry economizer 2 heats the to-be heated water
4
using the sensible heat of the exhaust gas, and is provided
.-
on the upstream side (an upstream duct 6) of the duct. The
exhaust gas subjected to the heat exchange with the to-beheated
water in the dry economizer 2 drops in temperature
owing to residual heat recovery. For example, when the
temperature of the exhaust gas flowing in the dry
economizer 2 is 300°C, the temperature of the exhaust gas
flowing out of the dry economizer 2 drops to 180°f. In
this case, for example, the inlet temperature of the to-be-
I
heated water to the dry economizer 2 may be 150°C, and the'
b
outlet temperature thereof may be 250°C.
The condensation economizer 4 is arranged on the
downstream. side of the dry economizer 2 to heat the to-be-
I
hekted water using the latent heat of the condensation of , the'exhaust gas, and is provided on the downstream side
(the downstream duct 8) of the' duct. The downstream duct 8
is connected to the upstream duct 6 to direct the exhaust
gas -to flow-upward. The condensation economizer 4 is
provided so that the exhaust gas amounts to the
condensation temperature at the vicinity of the upper part
5. In the predent embodiment, the condensation temperature
I of the exhaust gas is 58 to 62OC. For example, another dry
1 economizer, which lowers the teinperature of the exhaust gas,
may be provided on the upstream side of the condensation
economizer 4 so that the exhaust gas amounts to the
condensation temperature at the vicinity of the upper part
f
5 of the condensation economizer 4.
..b
[0028]
I In addition, the flow direction of the to-beheated
water flowing in the dry economizer 2 and the
condensation economizer 4 is provided so as to face the
flow direction of the exhaust gas.
Thus, since the flow direction of the to-be-heated
water flowing in the dry economizer 2 and the co3densation
economizer 4 is provided so as to face the flow direction
I
of the exhaust gas, the heat recovery efficiency can be I
improved.
[0029]
In this manner, the device 1 for recovering"
residual heat from exhaust gas mentioned above is
cohfigured such that the condensation economizer 4 is I
provided in the downstream duct 8 directing the exhaust gas
to flow upward, and the exhaust gas amounts to the
condensation temperature, at the vicinity of the upper part
5 of the condensation economizer 4. Thus, vapor in the
exhaust gas is condensed at the vicinity of the upper part
5 of the condensation economizer 4 and becomes the drain
(the condensed hater) . .
Since tQe-generated drain falls down from the
vicinity of the upper part 5 of'the condensation economizer
and comes into contact with the water pipe group
constituting the condensation economizer 4, the outer wall
of the water pipe is kept in the wet state from the upper
+
part to the lower part. For this reason, the drying and
.e
wetting cycle is able to be prevented in the water pipe
group of the condensation economizer 4, whereby the stress
corrosion cracking is able to be prevented.
Furthermore, since the generated drain falls down
so as to come into contact with the water pipe group and
face the exhaust gas of the upward flow when fallIi ng down
from the vicinity of the upper part 5 of the condensation
8
economizer 4, it is possible to increase the partial 1 '
b pressure of vapor in the exhaust gas flowing in the
condensation economizer 4. For this reason, the
condensation amount in the condensation economizer is
increased;the condensation efficiency rises, and the
rehidual heat recovery rate of the exhaust gas rises.
I In addition, the drain comes into contact with the
water pipe group of the conden'sation economizer 4 or the
exhaust gas of the upward 'flow, and then is discharged from
the drain outlet 7.
[0031]
' In addition, since the device 1 for recovering
residual heat from exhaust gas of the present embodiment is
configured such,that the condensation economizer 4 is
provided in the upstream duct G'provided with the dry
economizer 2 and in the downstream duct 8 that is connected
to the upstream duct 6 and directs the exhaust gas to flow
upward, it is possible to easily assemble and manufacture
t
the device for recovering residual heat.
-*
[0032]
Furthermore, as shown in Fig. 2, the device 1 for
recovering residual heat from exhaust gas may include a
spray nozzle 9 that sprays water toward the exhaust gas
flowing in the condensation economizer 4.
As shown in Fig. ZA, the spray nozzle 9 may be
provided on the lower part side (the exhaust gas If low ,
upstream side) of the condensation economizer 4, and, as
t
shown in Fig. ZB, the spray nozzle 9 may be provided in an'
b
inner part of the condensation economizer 4. Furthermore,
as shown in Fig. 2C, the spray nozzle 9 may be provided on
an upper part side (the exhaust gas flow downstream-side)
of the condensation economizer 4.
Thus, since water is sprayed toward the exhaust
gas flowing in the condensation economizer 4, it is
possible to further increaBe the partial pressure of vapor
in the exhaust gas flowing in the condensation economizer 4.
For this reason, the condensation amount in the
condens'ation economizer 4 is increased, the condensation
efficiency rise's, and the residual heat recovery rate of
the exhaust gas .,-ri-ses.
Particularly, as shown ?n Fig. 2C, when the spray
nozzle 9 is provided in the upper part side of the
condensation economizer 4, it is possible to expect that
the drying of the water pipe 11 constituting the
+
condensation economizer 4 is prevented, whereby the outer
.-
wall of the water pipe 11 is generally kept in the wet
state. Thus, it is possible to increase the partial
pressure of vapor in the exhaust gas and prevent the drying
and wetting cycle the condensation economizer which
is able to effectively prevent the stress corrosion
cracking.
In addition, the temperature of water to be
8
sprayed to the exhaust gas by the spray nozzle 9 is set to'
&
a temperature between the inlet temperature and the outlet
temperature of the to-be-heated water to the condensation I
economizer 4.
For example, when the inlet temperature of the tobeLheated
water to the condensation economizer 4 is 20°C, ,
and'the outlet temperature thereof is 60°C, as shown in Fig.
2A, the temperature of water tb be sprayed from the lower
part side of the condens.a The heat recovery section 16 gives the heat ' !
transfer layer plate 20 the residual heat of the exhaust
gas on the downstream side of'the exhaust gas flow of the
dry economizer 2 to recqvery the residual heat. In this
manner, the-heat of the exhaust gas of the upstream duct 6
to be transferred to the downstream side of the exhaust gas
flow of the condensation economizer 4 is obtained by being
recovered by the heat recovery section 16. Thus, it is
possible to lowex the temperature of the exhaust gas of the
downstream side of the exhaust gas flow of the dry
economizer 2. Accordingly, the temperature of the exhaust
gas is lowered before flowing in the condensation
economizer 4, whereby the exhaust gas is easily condensed
t
by the condensation economizer 4.
~-*
For example, when the temperature of the exhaust
gas discharged from the dry economizer 2 is 180°C, the
exhaust gas subjected to the heat recovery by the heat
recovery section 16 is lowered to 60 to 80°C.
The reheating section 18 reheats the exhaust gas
on the downstream side of the exhaust gas flow oflthe ,
condensation ecpnomizer 4 by the residual heat recovered to
the heat transfer layer plate 20 by the heat recovery I '
b
section 16. Thus, it is possible to transfer the heat of
the exhaust gas of the upstream duct 6 to the downstream 1
I
side of the exhaust gas flow of the condensation economizer^
- 4 and reheat the exhaust gas on the downstream side of the
> '
exhaust gas flow of the condensation economizer 4.
' Accordingly, it is possible to raise the temperature of the
exhaust gas, lower the relative humidity of the gas after
the mixture, and suppress 'the occurrence of white smoke.
F Oe~xa mple, when the temperature of the exhaust
gas discharged from the condensation economizer 4 is 30 to
50°C, the exhaust gas reheated by the reheating section 18
is raised to 80 to 100°C-.
The heating controller 22 controls the heating
state of the heater (the gas-gas heater) 14 based on the
detection result of the white-smoke detector 12. In the
present embodiment, the heating controller 22 may raise the
4
rotational speed of the gas-gas heater 14 &h the increase
in concentration of the white smoke based on the detection
result of the white-smoke detector 12. In addition, the
heating controller 22 is a controller, and drives the motor
24, which rotates the heat transfer layer plate 20 of the
gas-gas heater 14, based on the detection result of the
white-smoke detector 12.
In this manner, since the rotational spegd of the
gas-gas heater,14 is raised with the increase in
concentration of the white smoke based on the detection
b
result of the white-smoke detector 12, it is possible to
effectively adjust the temperature of the exhaust gas so
that the white smoke is not generated.
Third Embddiment
Next, a device for recovering residual heat
according to a third embodiment will be described.
Fig. 5 is a schematic configuration diagram that
illustrates-a device for recovering residual heat from
exhaust gas according to the third embodiment.
The devkce 1 for. recovering residual heat from
exhaust gas accqrding to the third embodiment has the same
configuration as the device 1 f6r recovering residual heat
described in the second embodiment except that a bypass
channel and a damper are provided instead of the gas-gas
heater 14 as the heater, and thus, the detailed description
t
of the same configuration will be omitted. - [0048]
As shown in Fig. 5, the heater includes a bypass
channel 28 and a damper 32. The bypass channel 28 connects
the upstream duct 6 with the downstream duct 8, and joins a
part of the exhaust gas of the upstream.duct 6 on the
downstream side of the exhaust gas flow of the condensation
economizer 4. The damper 32 controls the flow rate of the
exhaust gas of the bypass channel 28.
8
[0049]
b
In this case, the heating controller 36 increases
the opening amount of the damper 32 with the increase in
concentration of the white smoke based on the detection
result of the white-smoke detector 12. In addition, the
I
h&ting controller 36 is a controller, and drives the mot05
j
38, 'which operates the damper 32, based on the detection
result of the white-smoke detector 12.
As a -result, since it is possible to join a part
of the exhaust gas of the upstream duct 6 on the downstream
side of the exhaust gas flow of the condensation economizer
4, it is possidle to raise the temperature of the exhaust
gas of the down$tream side of the exhaust gas flow of the
condensation economizer 4 to subpress the occurrence of
white smoke.
Furthermore, since it is possible to increase the ,
opening amount of the damper 32 with the increase in
t
concentration of the white smoke based on the detection
.-Z
result of the white-smoke detector 12, it is possible to
control the flow rate of the exhaust gas of the bypass
channel 28 so that the white smoke is not generated. Thus,
it is possible to effectively adjust the temperature of the
exhaust gas.
In addition, since the heater including the bypass
channel 28 and the damper 32 has a simple struct~e, the,
equipment cost is able to be reduced.
?
L
In addition, the installation locations or the
numbers of the bypass channel and the damper are not
particularly limited, but'the installation locations may bes
changed and a plurality of them may be provided. For
exgmple, in order that the exhaust gas amounts to the P i
condensation temperature at the vicinity of the upper part
5 of the condensation economiz'er 4, a low temperature dry
economizer separate from,the dry economizer 2 may be
provided, and the bypass channel and the damper may be
provided on the downstream side of the low temperature dry
economizer.
~pecif$cally, as shown in Fig. 5, besides the
configuration mentioned above, a low temperature dry
economizer 26, a bypass channel'30, and a damper 34 may be
further included.
The low temperature dry economizer 26 is arranged
4
in the upstream duct 6 of the downstream side of the dry
-*
economizer 2 and performs the residual heat recovery of the
exhaust gas in a temperature area of the temperature lower
than that of the dry economizer 2. For example, when the
temperature of the exhaust gas discharged from the dry
economizer 2 is 180°C, the low temperature dry economizer
26 may be provided in the temperature area where the
exhaust gas subjected to the residual heat recovery by the
I
low temperature dry economizer 26 is lowered to 60 to 80°C.
?
By recovering the remaining residual heat of the 1 ,
b
exhaust gas discharged from the dry economizer 2 through
such a low temperature dry economizer 26, it is possible to 1
lower the temperature of the exhaust gas flowing in'the
condensation economizer 4 and enhance the condensation
I
efEiciency of the condensation economizer 4.
' In addition, although it is not illustrated, from
the viewpoint of improving the' heating efficiency,
outlet to-be-heated water of the low temperature dry
economizer 26 after the heat exchange may be used as an
inlet to-be-heated water of the dry.economizer 2 via a
deaerator.
[0053] 1,
The byppss channel 30 connects the upstream duct 6
with the downstream duct 8, and' joins a part of the exhaust
gas of the downstream side of the low temperature dry
economizer 26 on the downstream side of the exhaust gas
flow of the condensation economizer 4. The damper 34
?
controls the flow rate of the exhaust gas of the bypass
.-*
channel 30, that is, the flow rate of the exhaust subjected
to the residual heat recovery by the low temperature dry
economizer 26. Similarly to the damper 32 mentioned above,
the opening amount of the damper 34 is increased by driving
the motor the heating controller (controller) 36 with
the increase in concentration of the white smoke based on
the detection result of the white-smoke detector 12.
I I
[0054]
I
As a result, it is possible to select the I '
b temperature of the exhaust gas of the upstream duct 6 that
. I
is joined on the downstream side of the exhaust gas flow of
the condensation economizer 4. For example, from the
viewpoint ,of reliably performing the temperature control of
thb exhaust gas of the downstream side of the exhaust gas , flow of the condensation economizer 4 so that the white
smoke is not generated, a part' of the exhaust gas of the
downstream side of the loG temperature dry economizer 26
may be joined via the bypass channel 30 and the damper 34.
Furthermore, from the viewpoint of suppressing a decline in
heating efficiency, as shown in Fig. 5, a part of the
exhaust gas of &he downstream side of the dry economizer 2
having temperature-higher than that of the exhaust gas of
the downstream side of the low • rotational speed of the heat exchanger plate with increase , in concentration of the white smoke based on the detection
result of the white-smoke detector.
4. The'device for recovering residual heat according
to claim 2,
wherein the heater comprises: a bypass channel
^through which the' upstream duct is in communication with
the downstream duct-so that a portion of the exhaust gas in
the upstream d.uct flows into the downstream side of the
condensation economizer; and a damper which adjusts flow
rate of the portion of the exhaust gas flowing in the
bypass channel, and
wherein the heating controller increases an
'opening amount of the damper with increase in concentration
o'f the white smoke based on the detection result of the
- I . white-smoke detector. ,
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5. The device for recovering residual heat according
to any one of claims 1 to 4, further comprising:
a spray nozzle which sprays water to the exhaust
gas flowing in the condensation economizer,
wherein the water sprayed to the exhaust gas by
the spray nozzle has temperature between an inlet
i
temperature and .f.a»^0utlet temperature of the. to-be-heated
water in the condensation e'conomizer.
6. •. • The device for recovering residual heat according
to claim 1, wherein the to-be-heated water flows in the dry
economizer and the condensatio'n economizer in a direction
that is opposite to a direction of the exhaust gas.