U.S. patent application number 09/727581 was filed with the patent office on 2001-04-05 for exhaust heat recovery boiler.
Invention is credited to Egami, Norihide, Nagashima, Takayuki, Shimada, Hideaki.
Application Number | 20010000094 09/727581 |
Document ID | / |
Family ID | 17566130 |
Filed Date | 2001-04-05 |
United States Patent
Application |
20010000094 |
Kind Code |
A1 |
Shimada, Hideaki ; et
al. |
April 5, 2001 |
Exhaust heat recovery boiler
Abstract
An exhaust heat recovery boiler in which an exhaust gas
discharged from a gas turbine into a boiler duct to recover a heat
of the exhaust gas and ammonia is injected to and mixed with the
exhaust gas to reduce nitrogen oxide contained in the exhaust gas,
the exhaust heat recovery boiler comprising: a boiler duct of a
horizontal installation type having an inner hollow portion along
which an exhaust gas flows from an upstream side to, a downstream
side; a superheater; an evaporator; a denitration reactor; and an
economizer, which are disposed inside the boiler duct in this order
from the upstream side to the downstream side of the exhaust gas
flow therein. A drum is disposed outside the boiler duct and
connected to the evaporator and a downcomer pipe extending from the
drum into the boiler duct. An ammonia injection unit is disposed
inside the boiler duct for injecting ammonia, and the ammonia
injection unit is disposed upstream side of the evaporator closely
to the downcomer pipe unit on either one of upstream side and
downstream side of the downcomer pipe unit.
Inventors: |
Shimada, Hideaki;
(Yokohama-Shi, JP) ; Egami, Norihide;
(Yokohama-Shi, JP) ; Nagashima, Takayuki;
(Yokohama-Shi, JP) |
Correspondence
Address: |
OBLON SPIVAK MCCLELLAND MAIER & NEUSTADT PC
FOURTH FLOOR
1755 JEFFERSON DAVIS HIGHWAY
ARLINGTON
VA
22202
US
|
Family ID: |
17566130 |
Appl. No.: |
09/727581 |
Filed: |
December 4, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09727581 |
Dec 4, 2000 |
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09499451 |
Feb 7, 2000 |
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09499451 |
Feb 7, 2000 |
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09167714 |
Oct 7, 1998 |
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6050226 |
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Current U.S.
Class: |
122/7R ; 122/459;
422/148; 422/172 |
Current CPC
Class: |
Y02C 20/10 20130101;
F22B 1/1815 20130101; F22B 37/008 20130101 |
Class at
Publication: |
122/7.00R ;
122/459; 422/148; 422/172 |
International
Class: |
F22D 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 8, 1997 |
JP |
P9-276203 |
Claims
What is claimed is:
1. An exhaust heat recovery boiler in which an exhaust gas
discharged into a boiler duct to recover a heat of the exhaust gas
and ammonia is injected to and mixed with the exhaust gas so as to
reduce nitrogen oxide contained in the exhaust gas, said exhaust
heat recovery boiler comprising: a boiler duct of a horizontal
installation type having an inner hollow portion along which an
exhaust gas flows from an upstream side to a downstream side; a
superheater disposed inside the boiler duct at an upstream side of
the exhaust gas flow; an disposed downstream side of the
superheater; a denitration reactor disposed downstream side of the
evaporator; an economizer disposed downstream side of the
evaporator; a drum disposed outside the boiler duct and connected
to the evaporator; a downcomer pipe unit extending from the drum
into the boiler duct; and an ammonia injection unit disposed inside
the boiler duct for injecting ammonia, said ammonia injection unit
being disposed upstream side of said evaporator closely to said
downcomer pipe unit on either one of upstream side and downstream
side of the downcomer pipe unit.
2. An exhaust heat recovery boiler according to claim 1, wherein
said ammonia injection unit is disposed upstream side of the
downcomer pipe unit.
3. An exhaust heat recovery boiler according to claim 1, wherein
said ammonia injection unit is disposed downstream side of the
downcomer pipe unit.
4. An exhaust heat recovery boiler according to claim 1, wherein
said ammonia injection unit includes a plurality of ammonia
injection pipes, a plurality of ammonia injection pipe supporting
members and a number of ammonia injection nozzles, and said
downcomer pipe unit includes a plurality of downcomer pipes, said
ammonia injection pipe supporting members being disposed in
parallel to the downcomer pipes with respect to the exhaust gas
flow.
5. An exhaust heat recovery boiler according to claim 4, wherein
said ammonia injection pipe supporting members are arranged between
adjacent downcomer pipes, respectively.
6. An exhaust heat recovery boiler according to claim 4, wherein
said ammonia injection pipe supporting members are mounted to the
downcomer pipes.
7. An exhaust heat recovery boiler according to claim 4, wherein
said downcomer unit commonly serves as said ammonia injection pipe
supporting members.
8. An exhaust heat recovery boiler according to claim 1, wherein
said evaporator unit is composed of a plurality of heat transfer
tubes arranged so as to extend in parallel to each other.
9. An exhaust heat recovery boiler in which an exhaust gas
discharged into a boiler duct to recover a heat of the exhaust gas
and ammonia is injected to and mixed with the exhaust gas so as to
reduce nitrogen oxide contained in the exhaust gas, said exhaust
heat recovery boiler comprising: a boiler duct of a horizontal
installation type having an inner hollow portion along which an
exhaust gas flows from an upstream side to a downstream side; a
superheater disposed inside the boiler duct at an upstream side of
the exhaust gas flow; an evaporator unit disposed downstream side
of the superheater, said evaporator unit including a primary
evaporator and a secondary evaporator disposed downstream side of
the primary evaporator; a denitration reactor disposed downstream
side of the secondary evaporator; an economizer disposed downstream
side of the evaporator unit; a drum disposed outside the boiler
duct and connected to the evaporator unit; a downcomer pipe unit
extending from the drum into the boiler duct; and an ammonia
injection unit disposed inside the boiler duct for injecting
ammonia, said ammonia injection unit and said downcomer pipe unit
being disposed between said primary and secondary evaporators, said
ammonia injection unit being arranged closely to the downcomer pipe
on either one of upstream side and downstream side of the downcomer
pipe unit.
10. An exhaust heat recovery boiler according to claim 9, wherein
said ammonia injection unit is disposed upstream side of the
downcomer pipe unit.
11. An exhaust heat recovery boiler according to claim 9, wherein
said ammonia injection unit is disposed downstream side of the
downcomer pipe unit.
12. An exhaust heat recovery boiler according to claim 9, wherein
said ammonia injection unit includes a plurality of ammonia
injection pipes, a plurality of ammonia injection pipe supporting
members and a number of ammonia injection nozzles, and said
downcomer pipe unit includes a plurality of downcomer pipes, said
ammonia injection pipe supporting members being disposed in
parallel to the downcomer pipes with respect to the exhaust gas
flow.
13. An exhaust heat recovery boiler according to claim 12, wherein
said ammonia injection pipe supporting members are arranged between
adjacent downcomer pipes, respectively.
14. An exhaust heat recovery boiler according to claim 12, wherein
said ammonia injection pipe supporting members are mounted to the
downcomer pipes.
15. An exhaust heat recovery boiler according to claim 12, wherein
said downcomer unit commonly serves as said ammonia injection pipe
supporting members.
16. An exhaust heat recovery boiler in which an exhaust gas
discharged a boiler duct to recover a heat of the exhaust gas and
ammonia is injected to and mixed with the exhaust gas so as to
reduce nitrogen oxide contained in the exhaust gas, said exhaust
heat recovery boiler comprising: a boiler duct of a horizontal
installation type having an inner hollow portion along which an
exhaust gas flows from an upstream side to a downstream side; a
superheater disposed inside the boiler duct at an upstream side of
the exhaust gas flow; an evaporator disposed downstream side of the
superheater; a denitration reactor disposed downstream side of the
evaporator; an economizer disposed downstream side of the
evaporator; a drum disposed outside the boiler duct and connected
to the evaporator; a downcomer pipe unit extending from the drum
into the boiler duct; and an ammonia injection unit disposed inside
the boiler duct for injecting ammonia,; said evaporator being
composed of a plurality of heat transfer tubes which are arranged
in parallel to each other, said ammonia injection unit being
arranged in parallel to said heat transfer pipes and being
supported at upper and lower ends thereof by means of upper and
lower headers.
17. An exhaust heat recovery boiler according to claim 15, wherein
said ammonia injection unit is disposed downstream side of the
downcomer pipe unit.
18. An exhaust heat recovery boiler in which an exhaust gas
discharged into a boiler duct to recover a heat of the exhaust gas
and ammonia is injected to and mixed with the exhaust gas so as to
reduce nitrogen oxide contained in the exhaust gas, said exhaust
heat recovery boiler comprising: a boiler duct of a horizontal
installation type having an inner hollow portion along which an
exhaust gas flows from an upstream side to a downstream side; a
superheater disposed inside the boiler duct at an upstream side of
the exhaust gas flow; an evaporator disposed downstream side of the
superheater; a denitration reactor disposed downstream side of the
evaporator; an economizer disposed downstream side of the
evaporator; a drum disposed outside the boiler duct and connected
to the evaporator; a downcomer pipe unit extending from the drum
into the boiler duct; and an ammonia injection unit disposed inside
the boiler duct for injecting ammonia, said ammonia injection unit
being disposed upstream side of said evaporator and arranged
between said downcomer pipe unit and said superheater and said
ammonia injection unit being supported at upper and lower ends
thereof by means of upper and lower headers.
Description
BACKGROUND OF THE INVENTION
1. The present invention relates to an exhaust heat recovery
boiler, particularly, capable of reducing and removing a nitrogen
oxide (NOx) contained in an exhaust gas.
2. In recent years, in order to improve an efficiency of power
generation in the light of energy conservation, in addition to
power generation by a gas turbine, there is a tendency of employing
a combined cycle power generation plant which recovers an exhaust
heat of the exhaust gas of the gas turbine so as to generate a
steam and performs power generation by a steam turbine with the use
the generated steam. Further, in order to improve an efficiency of
power generation and a power generation output, the combined cycle
power generation plant tends to be further made into a large
capacity.
3. In the combined cycle power generation plant, an exhaust heat
recovery boiler is employed to recover an exhaust heat and to
generate a steam. The exhaust heat recovery boiler recovers a heat
of the exhaust gas discharged from, for example, a gas turbine or
diesel engine, and then, generates and supplies a driving steam for
a steam turbine and a process steam hot water. Further, taking
environmental protection into consideration, the exhaust heat
recovery boiler includes a denitrator for reducing a harmful
nitrogen oxide contained in the exhaust gas. In particular,
recently, there is a tendency of providing a high performance
denitrator which can remove 90% or more of the nitrogen oxide
contained in the exhaust gas, in the exhaust heat
recovery-boiler.
4. A conventional exhaust heat recovery boiler will be described
hereunder with reference to FIG. 22 which is a side view
schematically showing the exhaust heat recovery boiler, and FIG. 23
which is a top plan view of an ammonia injection section (unit) of
the exhaust heat recovery boiler.
5. As shown in these figures, a horizontal natural circulation type
exhaust heat recovery boiler is a reheat dual pressure type boiler,
which is opertively connected to, for example, a gas turbine G,
diesel engine, or the like. A boiler duct 14 is provided therein
with heat transfer pipes of a high pressure secondary superheater
15, a reheater 16, a high pressure primary superheater 13, a high
pressure evaporator 4, a low pressure superheater 17, a high
pressure economizer 18, a low pressure evaporator 19 and a low
pressure economizer 20, which are located successively in the
described order in the boiler duct from the upstream side to the
downstream side along an exhaust gas flow direction. Further, the
boiler duct 14 is provided therein with an ammonia injection
section 1 and an NOx removal reactor 5, and the upper portion of
the boiler is provided with a high pressure drum 6 and a low
pressure drum 21. A reference numeral 2 denotes an ammonia
injection section support member, a reference numeral 3 denotes a
high pressure drum downcomer pipe, a reference numeral 7 denotes an
ammonia injection pipe, and a reference numeral 8 denotes an
ammonia injection nozzle.
6. Further, it is to be noted that, in the above description, the
some members or units are disposed to be adaptable for high and low
pressures, but in an equipment having relatively small capacity,
these members or units may be utilized as one member or unit,
respectively.
7. Next, an operation of the aforesaid exhaust heat recovery boiler
will be described hereunder.
8. An exhaust gas flowing into the exhaust heat recovery boiler
successively passes through the high pressure secondary superheater
15, the reheater 16 and the high pressure primary superheater 13,
and then, is mixed with ammonia in the ammonia injection section 1.
Then, the exhaust gas passes through the high pressure evaporator
4, and thereafter, nitrogen oxide contained in the exhaust gas is
removed by means of the NOx removal reactor (denitration reactor or
denitrator) 5 including a catalyst layer facilitating a reduction
reaction. Further, the exhaust gas successively passes through the
low pressure superheater 17, the high pressure economizer 18, the
low pressure evaporator 19 and the low pressure economizer 20, and
then, is discharged to the atmospheric air.
9. The ammonia injection section 1 of the exhaust heat recovery
boiler is arranged on an upstream side of the high pressure
evaporator 4 with respect to the exhaust gas flow direction.
Further, ammonia needs to be uniformly mixed with the exhaust gas,
and for this reason, the ammonia injection section 1 is arranged at
a position separated from the denitration reactor 5 to some degree
in a manner that the high pressure evaporator 4 is interposed
between the injection section 1 and the denitration reactor 5. When
passing through the high pressure evaporator 4 having many heat
transfer pipes regularly arranged, the ammonia and the exhaust gas
are uniformly mixed. The ammonia is oxidized at a temperature of
490.degree. C. or more, and then, a nitrogen oxide is generated.
For this reason, it is not preferable to properly keep an NOx
removal efficiency. Thus, a proper exhaust gas temperature is
required, and then, in order to satisfy these conditions, the
ammonia injection section 1 is arranged on a downstream side of the
high pressure primary superheater 13 from the exhaust gas flow
direction and on the upstream side of the high pressure evaporator
4, and a planned gas temperature is about 470.degree. C. In this
manner, in the exhaust heat recovery boiler, a harmful nitrogen
oxide contained in the exhaust gas is removed while heat exchange
being made by the heat transfer pipes.
10. FIG. 24 is a view showing the ammonia injection section of FIG.
22 in the case of viewing from the exhaust gas flow direction.
11. In FIG. 24, the ammonia injection section 1 includes an ammonia
injection pipe(s) 7, an ammonia injection section support member(s)
2 and a number of ammonia injection nozzles 8 formed to the ammonia
injection pipe 3. The ammonia is mixed with an air in a mixer 22,
and then, passes through an ammonia injection section inlet
connecting pipe 23, an ammonia injection section header 24 and an
ammonia injection section inlet pipe 25, and thus, flows into an
ammonia injection pipe 7 supported by the ammonia injection section
support member 2. The ammonia flowing into the ammonia injection
pipe 7 is injected from many ammonia injection nozzles 8 provided
on the ammonia injection pipe 7, and then, is mixed with an exhaust
gas. These many ammonia injection nozzles 8 are vertically
alternately provided on the ammonia injection pipe 7 so that the
ammonia is uniformly mixed with the exhaust gas. Further, the flow
rate of ammonia is controlled by means of ammonia flow control
valves 26 so that the ammonia is uniformly mixed with the exhaust
gas. As described above, the ammonia injection section is
constructed in a manner that ammonia is uniformly injected to the
overall section of exhaust gas passage in the boiler duct.
12. As described above, the combined cycle power generation plant
has a tendency of being made into a large capacity, and for this
reason, the exhaust heat recovery boiler is also made into a large
size. Thus, this is a factor of causing an increase in an
installation space, cost and a unit price of power generation. In
order to avoid the above disadvantage, there is a need of saving a
space of the exhaust heat recovery boiler and making low cost
design. The conventional exhaust heat recovery boiler has a problem
of requiring a large space around the ammonia injection section and
a drum downcomer pipe and increasing the entire length of the
boiler.
13. Further, the combined cycle power generation plant is made into
a large capacity, thus increasing the gas turbine power output
while the exhaust gas temperature rising up. Accordingly, the
exhaust heat recovery boiler has also a tendency of being made into
high temperature and large capacity. For this reason, in the light
of environmental conservation, it is obliged for the exhaust heat
recovery boiler to include a high performance denitrator.
14. However, in the conventional exhaust heat recovery boiler, the
exhaust gas temperature rises up, and also, the temperature of the
ammonia injection section rises up depending upon a system for
supplying a cooling steam to a gas turbine. For this reason, there
is the possibility that ammonia injection is not performed at a
proper temperature. In other words, there is a problem that it is
difficult to realize high NOx removal efficiency in the exhaust
heat recovery boiler which is made into a high temperature and
large capacity.
SUMMARY OF THE INVENTION
15. An object of the present invention is to eliminate defects or
drawbacks encountered in the prior art mentioned above and to
provide an exhaust heat recovery boiler capable of saving and
effectively utilizing an installation space for the exhaust heat
recovery boiler by arranging an ammonia injection section to an
optimal position and capable of effectively removing a nitrogen
oxide contained in an exhaust gas in accordance with a high
temperature and large capacity exhaust heat recovery boiler.
16. This and other objects can be achieved according to the present
invention by providing, in one aspect, an exhaust heat recovery
boiler in which an exhaust gas discharged from, for example, gas
turbine, into a boiler duct to recover a heat of the exhaust gas
and ammonia is injected to and mixed with the exhaust gas so as to
reduce nitrogen oxide contained in the exhaust gas, the exhaust
heat recovery boiler comprising:
17. a boiler duct of a horizontal installation type having an inner
hollow portion along which an exhaust gas flows from an upstream
side to a downstream side;
18. a superheater disposed inside the boiler duct at an upstream
side of the exhaust gas flow;
19. an evaporator disposed downstream side of the superheater
superheater;
20. a denitration reactor disposed downstream side of the
evaporator;
21. an economizer disposed downstream side of the evaporator;
22. a drum disposed outside the boiler duct and connected to the
evaporator;
23. a downcomer pipe unit extending from the drum into the boiler
duct; and
24. an ammonia injection unit disposed inside the boiler duct for
injecting ammonia,
25. the ammonia injection unit being disposed upstream side of the
evaporator closely to the downcomer pipe unit on either one of
upstream side and downstream side of the downcomer pipe unit.
26. In another aspect, there is provided an exhaust heat recovery
boiler in which an exhaust gas discharged from, for example, a gas
turbine, into a boiler duct to recover a heat of the exhaust gas
and ammonia is injected to and mixed with the exhaust gas so as to
reduce nitrogen oxide contained in the exhaust gas, the exhaust
heat recovery boiler comprising:
27. a boiler duct of a horizontal installation type having an inner
hollow portion along which an exhaust gas flows from an upstream
side to a downstream side;
28. a superheater disposed inside the boiler duct at an upstream
side of the exhaust gas flow;
29. an evaporator unit disposed downstream side of the superheater,
the evaporator unit including a primary evaporator and a secondary
evaporator disposed downstream side of the primary evaporator;
30. a denitration reactor disposed downstream side of the
evaporator unit;
31. an economizer disposed downstream side of the evaporator
unit;
32. a drum disposed outside the boiler duct and connected to the
evaporator unit;
33. a downcomer pipe unit extending from the drum into the boiler
duct; and
34. an ammonia injection unit disposed inside the boiler duct for
injecting ammonia,
35. the ammonia injection unit and the downcomer pipe unit being
disposed between the primary and secondary evaporators, the ammonia
injection unit being arranged closely to the downcomer pipe on
either one of upstream side and downstream side of the downcomer
pipe unit.
36. In a further aspect, there is provided an exhaust heat recovery
boiler in which an exhaust gas discharged from, for example, a gas
turbine, into a boiler duct to recover a heat of the exhaust gas
and ammonia is injected to and mixed with the exhaust gas so as to
reduce nitrogen oxide contained in the exhaust gas, the exhaust
heat recovery boiler comprising:
37. a boiler duct of a horizontal installation type having an inner
hollow portion along which an exhaust gas flows from an upstream
side to a downstream side;
38. a superheater disposed inside the boiler duct at an upstream
side of the exhaust gas flow;
39. an evaporator disposed downstream side of the superheater;
40. a denitration reactor disposed downstream side of the
evaporator;
41. an economizer disposed downstream side of the evaporator;
42. a drum disposed outside the boiler duct and connected to the
evaporator;
43. a downcomer pipe unit extending from the drum into the boiler
duct; and
44. an ammonia injection unit disposed inside the boiler duct for
injecting ammonia,
45. the evaporator being composed of a plurality of heat transfer
tubes which are arranged in parallel to each other, the ammonia
injection unit being arranged in parallel to the heat transfer
pipes and being supported at upper and lower ends thereof by means
of upper and lower headers.
46. In a still further aspect, there is provided an exhaust heat
recovery boiler in which an exhaust gas discharged from, for
example, a gas turbine, into a boiler duct to recover a heat of the
exhaust gas and ammonia is injected to and mixed with the exhaust
gas so as to reduce nitrogen oxide contained in the exhaust gas,
the exhaust heat recovery boiler comprising:
47. a boiler duct of a horizontal installation type having an inner
hollow portion along which an exhaust gas flows from an upstream
side to a downstream side;
48. a superheater disposed inside the boiler duct at an upstream
side of the exhaust gas flow;
49. an evaporator disposed downstream side of the superheater;
50. a denitration reactor disposed downstream side of the
evaporator;
51. an economizer disposed downstream side of the evaporator;
52. a drum disposed outside the boiler duct and connected to the
evaporator;
53. a downcomer pipe unit extending from the drum into the boiler
duct; and
54. an ammonia injection unit disposed inside the boiler duct for
injecting ammonia,
55. the ammonia injection unit being disposed upstream side of the
evaporator and arranged between the downcomer pipe unit and the
superheater and the ammonia injection unit being supported at upper
and lower ends thereof by means of upper and lower headers.
56. In preferred embodiments of the above various aspect, the
ammonia injection unit is disposed on the upstream side or
downstream side of the downcomer pipe unit.
57. The ammonia injection unit includes a plurality of ammonia
injection pipes, a plurality of ammonia injection pipe supporting
members and a number of ammonia injection nozzles, and the
downcomer pipe unit includes a plurality of downcomer pipes, the
ammonia injection pipe supporting members being disposed in
parallel to the downcomer pipes with respect to the exhaust gas
flow. The ammonia injection nozzles are formed to two ammonia
injection pipes, which are arranged in the same level with respect
to the exhaust gas flow, the injection nozzles being formed in a
manner that injection nozzles formed to one ammonia injection pipe
and injection nozzles formed to another one ammonia injection pipe
are arranged alternately with respect to the exhaust gas flow
direction.
58. The ammonia injection pipe supporting members are arranged
between adjacent downcomer pipes, respectively. The ammonia
injection pipe supporting members may be mounted to the downcomer
pipes. The downcomer unit may commonly serve as the ammonia
injection pipe supporting members.
59. The evaporator unit is composed of a plurality of heat transfer
tubes arranged in parallel to each other.
60. According to the characters and structures of the exhaust heat
recovery boiler of the present invention mentioned above, the
ammonia injection unit (section) is arranged at the same position
as the drum downcomer pipe unit when viewing from the exhaust heat
recovery boiler. Thus, a dimension is reduced in the exhaust gas
flow direction of the exhaust heat recovery boiler, and therefore,
there can be provided a compact exhaust heat recovery boiler which
can save a space with low cost design. Further, the ammonia
injection section is supported by the downcomer pipe, so that the
above effects will be enhanced.
61. Furthermore, the evaporator may be divided, and the ammonia
injection unit and the boiler downcomer pipe unit are interposed
between the divided evaporators. Thus, even if the exhaust gas
temperature rises up due to a rise of the combustion temperature of
the prime mover, heat exchange is made up to a proper temperature,
and thereafter, ammonia is injected, and then, it is possible to
remove a nitrogen oxide. Therefore, space saving is achieved in the
exhaust heat recovery boiler, and the exhaust heat recovery boiler
is provided at a low cost. Further, a nitrogen oxide can be
sufficiently removed in a high temperature and large capacity
exhaust heat recovery boiler as compared with the conventional
arrangement, and it is possible to sufficiently take measures for
environmental protection in the high temperature and large capacity
exhaust heat recovery boiler.
62. Still furthermore, since no downcomer pipe is arranged on the
pipe group outlet of the vaporizer, the mixed gas smoothly flows
into the denitrator, and the catalyst is effectively acted.
Therefore, it is possible to improve the NOx removal efficiency
even with the same quantity of catalyst as compared with the
conventional case.
63. The nature and further characteristic features of the present
invention will be made more clear from the following descriptions
of preferred embodiments made with reference to the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
64. In the accompanying drawings:
65. FIG. 1 is a side view showing an ammonia injection section
(unit) according to a first embodiment of the present
invention;
66. FIG. 2 is a top plan view of the ammonia injection section as
viewed from an arrow II-II in FIG. 1;
67. FIG. 3 is a view showing the ammonia injection section shown in
FIG. 1 or FIG. 11 viewing it from an exhaust gas flow direction
(arrow III);
68. FIG. 4 is a side view showing an ammonia injection section
according to a modified embodiment of the first embodiment of the
present invention;
69. FIG. 5 is a top plan view showing the ammonia injection section
as viewed from an arrow V-V in FIG. 4;
70. FIG. 6 is a side view showing an ammonia injection section
according to a second embodiment of the present invention;
71. FIG. 7 is a top plan view of the ammonia injection section as
viewed from an arrow VII-VII in FIG. 6;
72. FIG. 8 is a view showing the ammonia injection section shown in
FIG. 6 viewing it from an exhaust gas flow direction (arrow
VIII);
73. FIG. 9 is a side view showing an ammonia injection section
according to a modified embodiment of the second embodiment of the
present invention;
74. FIG. 10 is a top plan view showing the ammonia injection
section as viewed from an arrow X-X in FIG. 9;
75. FIG. 11 is a side view showing an ammonia injection section
according to a third embodiment of the present invention;
76. FIG. 12 is a top plan view showing the ammonia injection
section as viewed from an arrow XII-XII in FIG. 11;
77. FIG. 13 is a side view showing an ammonia injection section
according to a modified embodiment of the third embodiment of the
present invention;
78. FIG. 14 is a top plan view showing the ammonia injection
section as viewed from an arrow XIV-XIV in FIG. 13;
79. FIG. 15 is a side view showing an ammonia injection section
according to a fourth embodiment of the present invention;
80. FIG. 16 is a top plan view showing the ammonia injection
section as viewed from an arrow XVI-XVI in FIG. 15;
81. FIG. 17 is a side view showing an ammonia injection section
according to a modified embodiment of the fourth embodiment of the
present invention;
82. FIG. 18 is a top plan view showing the ammonia injection
section as viewed from an arrow XVIII-XVIII in FIG. 17;
83. FIG. 19 is a side view showing an ammonia injection section
according to a fifth embodiment of the present invention;
84. FIG. 20 is a view showing the ammonia injection section shown
in FIG. 19 viewing it from an exhaust gas flow direction (arrow
XX);
85. FIG. 21 is a side view showing an ammonia injection section
according to a sixth embodiment of the present invention;
86. FIG. 22 is a side view schematically showing a conventional
exhaust heat recovery boiler;
87. FIG. 23 is a top plan view showing an ammonia injection section
as viewed from an arrow XXIII-XXIII in FIG. 22; and
88. FIG. 24 is a view showing the ammonia injection section of the
exhaust heat recovery boiler shown in FIG. 23 viewing it from an
exhaust gas flow direction (arrow XXIV).
DESCRIPTION OF THE PREFERRED EMBODIMENTS
89. Embodiments of the present invention will be described below
with reference to FIGS. 1 to 21 of the accompanying drawings, in
which like reference numerals are added to units or members
corresponding to those shown in FIG. 22 and the detailed
description of the common members are omitted herein, and that is,
hereunder, only the essential portions of the exhaust heat recovery
boiler of the present invention are mentioned for the sake of
convenience.
90. FIGS. 1 to 3 are views showing an ammonia injection section
according to a first embodiment of the present invention.
91. As shown in these figures, in this first embodiment, the
ammonia injection section (unit) 1 is arranged on an upstream side
of a high pressure evaporator 4 with respect to the exhaust gas
flow direction in the boiler duct 14 and at the same position as a
high pressure drum downcomer pipe of a high pressure drum 6, and
usually, a plurality of downcomer pipes are arranged so as to
extend in parallel to each other. Further, the high pressure drum
downcomer pipe 3 and an ammonia injection section support member 2
are arranged in parallel to the boiler horizontal direction, normal
to the exhaust gas flow direction in the boiler duct. The ammonia
injection section 1 includes plural pairs of ammonia injection
pipes 71, 72, each pair including two pipes arranged side by side,
a plurality of ammonia injection pipe support members 2 and a
number of ammonia injection nozzles formed to the respective
ammonia injection pipes. The two ammonia injection pipes 71 and 72
are arranged in parallel to each other in the exhaust gas flow
direction. The ammonia injection nozzles 8 are alternately provided
on each of the ammonia injection pipes 71 and 72 in the exhaust gas
flow direction. Thus, an exhaust gas is mixed with ammonia in the
ammonia injection section 1, and then, passes through the high
pressure evaporator 4, and thereafter, a nitrogen oxide is removed
by means of an NOx removal reactor 5 which functions as a
denitration reactor or denitrator.
92. According to this embodiment, the ammonia injection section 1
is arranged on an upstream side of a high pressure evaporator 4
with respect to the exhaust gas flow direction in the boiler duct
14 and at the same position as a high pressure drum downcomer pipe
3 of a high pressure drum 6. Thus, it is possible to save a space
in the exhaust gas flow direction. Further, the exhaust gas flows
from the ammonia injection section 1 into the denitration reactor 5
via the high pressure evaporator 4, which is composed of a
plurality of heat transfer pipes arranged in parallel to each
other, so that a nitrogen oxide can be removed in a state that
ammonia and exhaust gas are uniformly mixed with each other.
Furthermore, a mixed gas smoothly flows into the denitration
reactor 5 because no high pressure drum downcomer pipe 3 is
provided on a pipe group outlet of the high pressure evaporator 4,
and therefore, catalyst is effectively activated, so that the NOx
removal efficiency can be improved even the same quantity of
catalyst as compared with the conventional case.
93. FIGS. 4 and 5 are views showing an ammonia injection section
according to a modified embodiment of the first embodiment of the
present invention.
94. As shown in these figures, this embodiment differs from the
first embodiment in that the ammonia injection pipes 71 and 72 and
the ammonia injection nozzle 8 are arranged on a down stream side
of the high pressure drum downcomer pipe 3 with respect to the
exhaust gas flow direction in the boiler duct 14, and other
construction is substantially the same as that of the first
embodiment. Thus, like reference numerals are used to designate the
same components or units as those of the first embodiment, and the
overlapping explanation is omitted.
95. According to this embodiment, the ammonia injection section 1
and the high pressure drum downcomer pipe 3 are arranged at the
same position when viewing the side of the exhaust heat recovery
boiler. Thus, it is possible to save a space in the exhaust gas
flow direction. Further, the exhaust gas flows from the ammonia
injection section 1 into the denitration reactor 5 via the high
pressure evaporator 4, so that a nitrogen oxide can be removed in a
state that ammonia and exhaust gas are uniformly mixed with each
other. Furthermore, the mixed gas smoothly flows into the
denitration removal reactor 5 because no high pressure drum
downcomer pipe 3 is provided on a pipe group outlet of the high
pressure evaporator 4, and therefore, catalyst is effectively
activated, so that the NOx removal efficiency can be improved even
the same quantity of catalyst as compared with the conventional
case.
96. FIGS. 6 to 8 are views showing an ammonia injection section
according to a second embodiment of the present invention.
97. As shown in these figures, this second embodiment differs from
the first embodiment in that the high pressure drum downcomer pipe
3 functions as the ammonia injection section support member 2 in
order to eliminate the ammonia injection section support member,
and other construction is the same as that of the first embodiment.
Thus, like reference numerals are used to designate the same
components as those of the first embodiment, and the overlapping
explanation is omitted.
98. In this second embodiment, like the first embodiment, the
exhaust gas is mixed with ammonia in the ammonia injection section
1, and then, passes through the high pressure evaporator 4, and
thereafter, a nitrogen oxide is removed by means of the denitration
reactor 5. Further, the high pressure drum downcomer pipe 3
functions as the ammonia injection section support member 2, so
that the ammonia injection section support member is dispensed.
Therefore, the number of components can be reduced.
99. FIGS. 9 and 10 are views showing an ammonia injection section
according to a modified embodiment of the second embodiment of the
present invention.
100. As shown in these figures, this embodiment differs from the
second embodiment in that the ammonia injection pipes 71 and 72 and
the ammonia injection nozzle 8 are arranged on a down stream side
of the high pressure drum downcomer pipe 3 with respect to the
exhaust gas flow direction in the boiler duct 14, and other
construction is the same as that of the first embodiment. Thus,
like reference numerals are used to designate the same components
as those of the first embodiment, and the overlapping explanation
is omitted.
101. According to this embodiment, the ammonia injection section 1
and the high pressure drum downcomer pipe 3 are arranged at the
same position when viewing the side of the exhaust heat recovery
boiler. Thus, it is possible to save a space in the exhaust gas
flow direction. Further, the exhaust gas flows from the ammonia
injection section 1 into the denitration reactor 5 via the high
pressure evaporator 4, so that a nitrogen oxide can be removed in a
state that ammonia and exhaust gas are uniformly mixed with each
other. Furthermore, the mixed gas smoothly flows into the
denitration reactor 5 because no high pressure drum downcomer pipe
3 is provided on a pipe group outlet of the high pressure
evaporator 4, and therefore, catalyst is effectively activated, so
that the NOx removal efficiency can be improved even with the same
quantity of catalyst as compared with the conventional case.
102. FIGS. 11 and 12 are views showing an ammonia injection section
according to a third embodiment of the present invention.
103. As shown in these figures, this third embodiment differs from
the first embodiment in that the high pressure evaporator 4 is
divided into a first high pressure evaporator section 9 and a
second high pressure evaporator section 10 and that the ammonia
injection section 1 and the high pressure drum downcomer pipe 3 are
interposed between these first and second high pressure evaporator
sections 9 and 10, and other construction is the same as that of
the first embodiment. Thus, like reference numerals are used to
designate the same components as those of the first embodiment, and
the overlapping explanation is omitted.
104. In this third embodiment, the ammonia injection section 1 and
the high pressure drum downcomer pipe 3 are arranged at the same
position when view the side of the exhaust heat recovery boiler,
like the first and second embodiments. Further, the high pressure
drum downcomer pipe 3 and the ammonia injection section support
member 2 are arranged in parallel in the horizontal direction, like
the first embodiment. The exhaust gas passes through the first high
pressure evaporator section 9, and then, is mixed with ammonia in
the ammonia injection section 1. Further, the exhaust gas passes
through the second high pressure evaporator section 10, and
thereafter, a nitrogen oxide is removed by means of the denitration
reactor 5. Therefore, according to this third embodiment, it is
possible to improve the NOx removal efficiency as compared with the
conventional case.
105. FIGS. 13 and 14 are views showing an ammonia injection section
according to a modified embodiment of the third embodiment of the
present invention.
106. As shown in these figures, this embodiment differs from the
third embodiment in that the ammonia injection pipes 71 and 72 and
the ammonia injection nozzles 8 are arranged on a down stream side
of the high pressure drum downcomer pipe 3 with respect to the
exhaust gas flow direction in the boiler duct 14, and other
construction is the same as that of the first embodiment. Thus,
like reference numerals are used to designate the same components
as those of the first embodiment, and the overlapping explanation
is omitted.
107. According to this embodiment, as the ammonia injection pipes
71, 72 and the ammonia injection are arranged on a downstream side
of the high pressure drum downcomer pipe 3 with respect to the
exhaust gas flow direction, in addition to reduction in space, in
the exhaust gas flow direction, of the exhaust heat recovery
boiler, the exhaust gas passes more heat transfer pipe groups than
the conventional one before it reaches the ammonia injection
section 1 so that the exhaust gas reaches the ammonia injection
section 1 after the heat exchanges are performed many times.
108. Further, since the temperature difference between the inlet of
the exhaust heat recovery boiler and the ammonia injection section
1 becomes large, if the temperature of the exhaust gas at the inlet
of the exhaust heat recovery boiler is higher than the conventional
one, the temperature of the exhaust gas is reduced up to a proper
temperature so that the exhaust gas can be guided into the ammonia
injection section 1. Accordingly, it is possible to increase the
exhaust heat recovery efficiency and denitration efficiency.
109. FIGS. 15 and 16 are views showing an ammonia injection section
according to a fourth embodiment of the present invention.
110. As shown in these figures, this fourth embodiment differs from
the third embodiment in that the high pressure drum downcomer pipe
3 also functions as the ammonia injection section support member 2
in order to eliminate the ammonia injection section support member,
and other construction is the same as that of the first embodiment.
Thus, like reference numerals are used to designate the same
components as those of the first embodiment, and the overlapping
explanation is omitted.
111. In this fourth embodiment, like the third embodiment, the
exhaust gas is mixed with ammonia in the ammonia injection section
1, and then, passes through the high pressure evaporator 4, and
thereafter, a nitrogen oxide is removed by means of the denitration
reactor 5. Further, the high pressure drum downcomer pipe 3 also
functions as the ammonia injection section support member 2, so
that the ammonia injection section support member is dispensed.
Therefore, the number of components can be reduced.
112. FIGS. 17 and 18 are views showing an ammonia injection section
according to a modified embodiment of the fourth embodiment of the
present invention.
113. As shown in these figures, this embodiment differs from the
fourth embodiment in that the ammonia injection pipes 71 and 72 and
the ammonia injection nozzles 8 are arranged on a down stream side
of the high pressure drum downcomer pipe 3 with respect to the
exhaust gas flow direction in the boiler duct 14, and other
construction is the same as that of the first embodiment. Thus,
like reference numerals are used to designate the same components
as those of the first embodiment, and the overlapping explanation
is omitted.
114. According to this embodiment, like the third embodiment, it is
possible to improve an exhaust heat recovery and an NOx removal
efficiency, and further, the support member is dispensed, so that
the number of components can be reduced.
115. FIGS. 19 and 20 are views showing an ammonia injection section
according to a fifth embodiment of the present invention.
116. As shown in these figures, in this fifth embodiment, the
ammonia injection section 1 is constructed in a manner that the
ammonia injection pipe 7 is connected with the use of an upper pipe
header 11 and a lower pipe header 12. Further, the ammonia
injection section 1 is inserted from the vertical direction, and is
arranged on an intermediate portion of the high pressure evaporator
4 which is composed of a plurality of heat transfer pipes as
mentioned before.
117. According to this fifth embodiment, in the ammonia injection
section 1, upper and lower pipe headers 11 and 12 are used as like
a heat transfer pipe, so that the ammonia injection section can be
located from the vertical direction. Further, like the third and
fourth embodiments, a space in the exhaust gas flow direction is
saved, and it is possible to perform ammonia injection at a proper
exhaust gas temperature.
118. FIG. 21 is a view showing an ammonia injection section
according to a sixth embodiment of the present invention.
119. As shown in FIG. 21, like the fifth embodiment, the ammonia
injection section 1 is constructed in a manner that the ammonia
injection pipe 7 is connected with the use of an upper pipe header
11 and a lower pipe header 12. Further, the ammonia injection
section 1 is inserted from the vertical direction and is arranged
on the downstream side of the high pressure primary superheater 13
with respect to the exhaust gas flow direction. Further, the
ammonia injection pipe 7 and the ammonia injection nozzle 8 have
the same arrangement as that of the fifth embodiment of FIG.
20.
120. According to this sixth embodiment, like the fifth embodiment,
the ammonia injection section 1 is constructed with the use of
upper and lower pipe headers 11 and 12. Therefore, a space in the
exhaust gas flow direction is saved, and it is possible to perform
ammonia injection at a proper exhaust gas temperature.
121. Further, it is to be noted that the present invention is not
limited to the described embodiment and many other changes,
modifications and combinations may be made without departing from
the scopes of the appended claims.
122. For example, in the aforementioned various embodiments,
although some units or members, such as superheater, evaporator,
drum, downcomer and economizer, are utilized for high and low
pressures, in the case of an equipment of relatively small
capacity, only one unit or member may be utilized,respectively.
That is, in the described embodiments, the units or members for low
pressure may be eliminated.
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