U.S. patent application number 09/789774 was filed with the patent office on 2001-09-20 for gas turbine and steam turbine installation.
Invention is credited to Hannemann, Frank, Schiffers, Ulrich.
Application Number | 20010022077 09/789774 |
Document ID | / |
Family ID | 7877786 |
Filed Date | 2001-09-20 |
United States Patent
Application |
20010022077 |
Kind Code |
A1 |
Hannemann, Frank ; et
al. |
September 20, 2001 |
Gas turbine and steam turbine installation
Abstract
A gas turbine and steam turbine installation has a waste-heat
steam generator whose heating surfaces are connected into the
water/steam cycle of the steam turbine. A gasification device is
connected upstream of the gas turbine in order to provide an
integrated gasification of a fossil fuel. Reliable operation of a
saturator which is connected into a fuel line is ensured
independently of the operating condition of the gasification
device. For this purpose, a saturator-water heat exchanger
connected with its secondary side into the saturator cycle is
supplied, on its primary side, with feed water extracted from the
water/steam cycle of the steam turbine. Thus it is possible to heat
the feed water cooled in the saturator-water heat exchanger through
the use of a partial flow of compressed air, and it is possible to
supply the partial flow of compressed air to an air separation unit
connected upstream of the gasification device.
Inventors: |
Hannemann, Frank; (Spardorf,
DE) ; Schiffers, Ulrich; (Eckental, DE) |
Correspondence
Address: |
LERNER AND GREENBERG P.A.
Post Office Box 2480
Hollywood
FL
33022-2480
US
|
Family ID: |
7877786 |
Appl. No.: |
09/789774 |
Filed: |
February 20, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09789774 |
Feb 20, 2001 |
|
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|
PCT/DE99/02440 |
Aug 4, 1999 |
|
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Current U.S.
Class: |
60/39.182 ;
122/7R |
Current CPC
Class: |
F25J 2240/82 20130101;
F25J 3/04618 20130101; F25J 3/04127 20130101; F25J 3/046 20130101;
Y02E 20/18 20130101; Y02P 80/15 20151101; Y02E 20/16 20130101; F25J
3/04545 20130101; F01K 23/068 20130101; F25J 3/04575 20130101; F25J
3/04606 20130101; F25J 3/04018 20130101; F25J 2240/70 20130101;
Y02T 10/12 20130101 |
Class at
Publication: |
60/39.182 ;
122/7.00R |
International
Class: |
F02C 006/18 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 17, 1998 |
DE |
198 37 251.5 |
Claims
We claim:
1. A turbine installation, comprising: a gas turbine having a
combustion chamber and a flue gas side; a steam turbine having a
water/steam cycle; a waste-heat steam generator connected
downstream of said flue gas side of said gas turbine, said
waste-heat steam generator having heating surfaces connected into
said water/steam cycle of said steam turbine; a fuel line; a
gasification device for providing gasified fuel, said gasification
device being connected upstream of said combustion chamber of said
gas turbine via said fuel line; a saturator cycle for guiding a
waterflow; a saturator connected into said saturator cycle and into
said fuel line, said saturator guiding the gasified fuel in a
counterflow to the water flow guided in said saturator cycle; a
saturator-water heat exchanger connected, with a secondary side
thereof, into said saturator cycle, said saturator-water heat
exchanger being supplied, on a primary side thereof, with feed
water extracted from said water/steam cycle of said steam turbine,
said saturator-water heat exchanger heating the water flow and
cooling the feed water; an air separation unit connected upstream
of said gasification device; an air compressor; an extraction air
line connecting said air compressor to said air separation unit for
providing a partial flow of compressed air to said air separation
unit; a feed water tank allocated to said waste-heat steam
generator; a feed water line connecting said saturator-water heat
exchanger at an outlet side thereof to said feed water tank; and a
further heat exchanger connected with a primary side thereof in
said extraction air line, said further heat exchanger being
connected with a secondary side thereof into said feed water line,
and said further heat exchanger heating the feed water and cooling
the partial flow of compressed air.
2. The turbine installation according to claim 1, wherein: said air
separation unit has an inlet side and receives at said inlet side
the partial flow of compressed air compressed in said air
compressor associated with said gas turbine; and said gasification
device receives oxygen from said air separation unit.
3. The turbine installation according to claim 1, wherein: said
saturator cycle defines a flow direction for the water flow; and a
feed line opens into said saturator cycle upstream of said
saturator-water heat exchanger as seen in the flow direction of the
water flow.
4. The turbine installation according to claim 2, wherein: said
saturator cycle defines a flow direction for the water flow; and a
feed line opens into said saturator cycle upstream of said
saturator-water heat exchanger as seen in the flow direction of the
water flow.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of copending
International Application No. PCT/DE99/02440, filed Aug. 4, 1999,
which designated the United States.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a gas turbine and steam turbine
installation with a waste-heat steam generator connected downstream
of a gas turbine. The heating surfaces of the waste-heat steam
generator are connected into the water/steam cycle of a steam
turbine. A gasification device for gasifying fuel is connected,
with a fuel line, upstream of a combustion chamber of the gas
turbine. A saturator is connected into the fuel line. The gasified
fuel is guided in counterflow to a water flow which is guided in a
saturator cycle.
[0004] A gas turbine and steam turbine installation with integrated
gasification of fossil fuel usually includes a fuel gasification
device which is connected, at the outlet end, to the combustion
chamber of the gas turbine via a number of components provided for
gas cleaning. The waste-heat steam generator can then be connected
downstream of the gas turbine, at a flue gas side. The heating
surfaces of the waste-heat steam generator are connected into the
water/steam cycle of the steam turbine. Such an installation is
known, for example, from Published UK Patent Application GB-A 2 234
984.
[0005] In order to reduce the pollutant emission during the
combustion of the gasified fossil fuel, a saturator is connected,
in this installation, into the fuel line between the gasification
device and the combustion chamber of the gas turbine. The gasified
fuel is loaded with water vapor in the saturator. For this purpose,
the gasified fuel flows through the saturator in counterflow to a
flow of water which is guided within a water cycle. This water
cycle is designated as saturator cycle. In order to set a
temperature level in the saturator which is sufficient for loading
the gasified fuel with water vapor, heat is coupled into the
saturator cycle by cooling the tapped or extracted air and/or by
cooling the crude gas from the fuel gasification.
[0006] In this installation, however, the operation of the
saturator depends on the operating condition of the gasification
device and/or on the operating condition of an air separation unit
connected upstream of the gasification device, so that this concept
only has limited flexibility. With respect to control, furthermore,
such a concept is comparatively complicated and therefore
susceptible to failure.
[0007] U.S. Pat. No. 5,319,924 discloses to preheat, in a heat
exchanger, the feed water to be fed into a saturator, wherein it is
possible to provide the heat exchanger with uncleaned crude gas on
the primary side. In addition, a saturator configured as a fuel
humidifier is known from Published, Non-Prosecuted Patent
Application DE 43 21 081 in which a heat exchanger, which is
supplied with feed water on the primary side, is provided for
preheating the saturator water.
[0008] In the article "Effiziente und umweltfreundliche
Stromerzeugung im GUD-Kraftwerk mit integrierter Vergasung"
[Efficient and environmentally friendly power production in a gas
and steam power plant with integrated gasification] by G. Haupt in
"Elektrotechnik und Informationstechnik" [Electrical engineering
and information technology], AT, Springer Verlag, Vienna, Volume
113, No. 1,2 (February 1996), pages 102-105, the heating in a heat
exchanger of a water flow which is to be fed into a saturator is
described. The water flow is heated in a heat exchange with feed
water extracted from the water/steam cycle of the steam turbine and
supplied in a dedicated reservoir ("flash tank") connected into a
circulating circuit. A heat exchanger is connected into this
circulating circuit and in the heat exchanger the feed water
absorbs heat from a partial flow of compressed air, the air being
appropriately cooled in the process.
SUMMARY OF THE INVENTION
[0009] It is accordingly an object of the invention to provide a
turbine installation which overcomes the above-mentioned
disadvantages of the heretofore-known turbine installations of this
general type and which allows, in a particularly simple manner,
reliable operation of the saturator even under different operating
conditions.
[0010] With the foregoing and other objects in view there is
provided, in accordance with the invention, a turbine installation,
including:
[0011] a gas turbine having a combustion chamber and a flue gas
side;
[0012] a steam turbine having a water/s team cycle;
[0013] a waste-heat steam generator connected downstream of the
flue gas side of the gas turbine, the waste-heat steam generator
having heating surfaces connected into the water/steam cycle of the
steam turbine;
[0014] a fuel line;
[0015] a gasification device for providing gasified fuel, the
gasification device being connected upstream of the combustion
chamber of the gas turbine via the fuel line;
[0016] a saturator cycle for guiding a waterflow;
[0017] a saturator connected into the saturator cycle and into the
fuel line, the saturator guiding the gasified fuel in a counterflow
to the water flow guided in the saturator cycle;
[0018] a saturator-water heat exchanger connected, with a secondary
side thereof, into the saturator cycle, the saturator-water heat
exchanger being supplied, on a primary side thereof, with feed
water extracted from the water/steam cycle of the steam turbine,
the saturator-water heat exchanger heating the water flow and
cooling the feed water;
[0019] an air separation unit connected upstream of the
gasification device;
[0020] an air compressor;
[0021] an extraction air line connecting the air compressor to the
air separation unit for providing a partial flow of compressed air
to the air separation unit;
[0022] a feed water tank allocated to the waste-heat steam
generator;
[0023] a feed water line connecting the saturator-water heat
exchanger at an outlet side thereof to the feed water tank; and
[0024] a further heat exchanger connected with a primary side
thereof in the extraction air line, the further heat exchanger
being connected with a secondary side thereof into the feed water
line, and the further heat exchanger heating the feed water and
cooling the partial flow of compressed air.
[0025] In other words, the object of the invention is achieved by a
saturator-water heat exchanger, which is connected on the secondary
side into the saturator cycle to heat the water flow, and which can
be supplied, on the primary side, with feed water extracted from
the water/steam cycle of the steam turbine, wherein it is possible
to heat the feed water cooled in the saturator-water heat exchanger
through the use of a partial flow of compressed air, wherein it is
possible to supply the partial flow of compressed air to an air
separation unit connected upstream of the gasification device, and
wherein it is possible to connect a further heat exchanger on the
primary side in an extraction air line connecting the air
compressor to the air separation unit in order to cool the partial
flow of compressed air, the secondary side of the further heat
exchanger is connected into a feed water line connecting the
saturator-water heat exchanger at the outlet end to a feed water
tank associated with the waste-heat steam generator.
[0026] According to another feature of the invention, the air
separation unit has an inlet side and receives at the inlet side
the partial flow of compressed air compressed in the air compressor
associated with the gas turbine; and the gasification device
receives oxygen from the air separation unit.
[0027] According to a further feature of the invention, the
saturator cycle defines a flow direction for the water flow; and a
feed line opens into the saturator cycle upstream of the
saturator-water heat exchanger as seen in the flow direction of the
water flow.
[0028] The invention is based on the consideration that a reliable
operation of the saturator is made possible even when there are
differing operating conditions, and therefore a particularly high
flexibility of the gas turbine and steam turbine installation is
achieved in that the saturator can be operated independently of the
operating parameters of the gasification device and the air
separation unit. In this connection, the coupling of the heat into
the saturator cycle, in particular, should not take place directly
through the use of a medium flowing out of the gasification device
or through the use of tapped or extracted air flowing into the air
separation unit. Instead of this, coupling of heat into the
saturator cycle is, rather, provided through the use of a medium
extracted from the water/steam cycle of the steam turbine, such
that the operating parameters for the gasification device and/or
the air separation unit, on the one hand, and the saturator, on the
other, can be set independently of one another. The control devices
necessary for operating these components can also, therefore, be
comparatively simply constructed.
[0029] In a particularly advantageous further embodiment, oxygen
from an air separation unit can be supplied to the gasification
device, wherein the air separation unit can, for its part, be
subjected at the inlet end to a partial flow of air compressed in
an air compressor associated with the gas turbine, a further heat
exchanger being connected on the primary side in an extraction air
line connecting the air compressor to the air separation unit in
order to cool the partial flow of compressed air, the secondary
side of the further heat exchanger is connected into a feed water
line connecting the saturator-water heat exchanger at the output
end to a feed water tank associated with the waste-heat steam
generator. Such a configuration ensures a particularly high
installation efficiency. The feed water flowing to the
saturator-water heat exchanger is initially cooled by the thermal
coupling into the water flow guided in the saturator cycle. In the
further heat exchanger connected on the feed water side downstream
of the saturator-water heat exchanger, the cooled feed water then
experiences reheating, wherein the partial flow of compressed air,
also referred to as tapped air or extracted air, flowing to the air
separation unit, is simultaneously cooled. Coupling of heat from
the tapped air flow into the water/steam cycle of the steam turbine
therefore occurs to provide a particularly large recovery of
heat.
[0030] In order to compensate for losses in the water flow guided
in the saturator cycle, for example because of the loading or
charging of the gasified fuel with water vapor in the saturator, a
feed line expediently opens into the saturator cycle, the entry
location of the feed line into the saturator cycle being provided
before the saturator-water heat exchanger, viewed in the flow
direction of the water flow, in order to provide a particularly
high installation efficiency in a particularly advantageous
embodiment. With such a configuration, a particularly high transfer
of heat from the feed water to the water flow guided in the
saturator cycle is ensured. The feed water therefore flows out of
the saturator-water heat exchanger with a particularly low
temperature so that, particularly when the cooled feed water is
used for cooling the tapped (extracted) air, a particularly
effective cooling of the tapped air is also made possible.
[0031] The advantages achieved by the invention result from the
fact that because of the coupling of heat into the saturator cycle
through the use of feed water extracted from the water/steam cycle
of the steam turbine, reliable operation of the saturator is made
possible independent of the operating condition of the gasification
device. In consequence, the gas turbine in particular can also be
operated within specified parameter limits independent of the
operating condition of the gasification device. Such a concept for
coupling in heat is therefore particularly flexible and, in
particular, is also independent of the integration concept, i.e.
independent of the type of air supply for the air separation unit
and the components employed for that purpose. Because of the use of
the feed water, cooled due to the heat transfer to the water flow,
for cooling the tapped air from the air separation unit, a
particularly high installation efficiency is also ensured.
[0032] Other features which are considered as characteristic for
the invention are set forth in the appended claims.
[0033] Although the invention is illustrated and described herein
as embodied in a gas turbine and steam turbine installation, it is
nevertheless not intended to be limited to the details shown, since
various modifications and structural changes may be made therein
without departing from the spirit of the invention and within the
scope and range of equivalents of the claims.
[0034] The construction and method of operation of the invention,
however, together with additional objects and advantages thereof
will be best understood from the following description of specific
embodiments when read in connection with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWING
[0035] FIG. 1, which is composed of FIGS. 1a and 1b, is a schematic
diagram of a gas turbine and steam turbine installation.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] Referring now to the drawing in detail there is shown a gas
turbine and steam turbine installation 1 which includes a gas
turbine installation 1a and a steam turbine installation 1b. The
gas turbine installation 1a includes a gas turbine 2 with,
connected to it, an air compressor 4 and a combustion chamber 6,
which is connected upstream of the gas turbine 2 and is connected
to a compressed air line 8 of the compressor 4. The gas turbine 2,
the air compressor 4 and a generator 10 are located on a common
shaft 12.
[0037] The steam turbine installation 1b includes a steam turbine
20 with, coupled to it, a generator 22 and, in a water/steam cycle
24, a condenser 26 and a waste-heat steam generator 30 connected
downstream of the steam turbine 20. The steam turbine 20 consists
of a first pressure stage or a high-pressure part 20a and a second
pressure stage or a medium-pressure part 20b and a third pressure
stage or a low-pressure part 20c, which drive the generator 22 via
a common shaft 32.
[0038] An exhaust gas line 34 is connected to an inlet 30a of the
waste-heat steam generator 30 in order to feed a working medium AM
or flue gas expanded in the gas turbine 2 into the waste-heat steam
generator 30. The expanded working medium AM from the gas turbine 2
leaves the waste-heat steam generator 30 via its outlet 30b in the
direction of a chimney (not shown).
[0039] The waste-heat steam generator 30 includes a condensate
preheater 40 which can be fed, at its inlet end, with condensate K
from the condenser 26 via a condensate line 42, into which is
connected a condensate pump unit 44. At its outlet end, the
condensate preheater 40 is connected via a line 45 to a feed water
tank 46. In order, if required, to bypass the condensate preheater
40, the condensate line 42 can, in addition, be connected directly
to the feed water tank 46 via a bypass line (not shown). The feed
water tank 46 is connected via a line 47 to a high-pressure feed
pump 48, with medium pressure extraction.
[0040] The high-pressure feed pump 48 brings the feed water S
flowing from the feed water tank 46 to a pressure level suitable
for a high-pressure stage 50 of the water/steam cycle 24 associated
with the high-pressure part of the steam turbine 20. The feed water
S--which is at a high pressure--can be supplied to the
high-pressure stage 50 via a feed water preheater 52 which, at its
outlet end, is connected to a high-pressure drum 58 via a feed
water line 56 which can be shut off by a valve 54. The
high-pressure drum 58 is connected to a high-pressure evaporator 60
provided in the waste-heat steam generator 30 for the formation of
a water/steam circuit 62. For the removal of the live steam F, the
high-pressure drum 58 is connected to a high-pressure superheater
64 provided in the waste-heat steam generator 30, the high-pressure
superheater 64 being connected at its outlet end to the steam inlet
66 of the high-pressure part 20a of the steam turbine 20.
[0041] The steam outlet 68 of the high-pressure part 20a of the
steam turbine 20 is connected via a reheater 70 to the steam inlet
72 of the medium-pressure part 20b of the steam turbine 20. The
steam outlet 74 of the medium-pressure part 20b is connected via a
transfer line 76 to the steam inlet 78 of the low-pressure part 20c
of the steam turbine 20. The steam outlet 80 of the low-pressure
part 20c of the steam turbine 20 is connected via a steam line 82
to the condenser 26 so that a closed water/steam cycle 24
results.
[0042] In addition, a branch line 84 branches off from the
high-pressure feed pump 48 at an extraction location at which the
condensate K has reached a medium pressure. This branch line 84 is
connected via a further feed water preheater 86 or medium-pressure
economizer to a medium-pressure stage 90 of the water/steam cycle
associated with a medium-pressure part 20b of the steam turbine 20.
For this purpose, the second feed water preheater 86 is connected
at its outlet end via a feed water line 94, which can be shut off
by a valve 92, to a medium-pressure drum 96 of the medium-pressure
stage 90. The medium-pressure drum 96 is connected to a heating
surface 98 provided in the waste-heat steam generator 30 and
configured as a medium-pressure evaporator in order to form a
water/steam circuit 100. For the removal of medium-pressure live
steam F', the medium-pressure drum 96 is connected via a steam line
102 to the reheater 70 and therefore to the steam inlet 72 of the
medium-pressure part 20b of the steam turbine 20.
[0043] A further line 110, which is provided with a low-pressure
feed pump 107, which can be shut off by a valve 108 and which is
connected to a low-pressure stage 120 of the water/steam cycle 24
associated with the low-pressure part 20c of the steam turbine 20,
branches off from the line 47. The low-pressure stage 120 includes
a low-pressure drum 122, which is connected, in order to form a
water/steam circuit 126, to a heating surface 124 provided in the
waste-heat steam generator 30 and configured as a low-pressure
evaporator. In order to remove low-pressure live steam F", the
low-pressure drum 122 is connected to the transfer line 76 via a
steam line 128, into which is connected a low-pressure superheater
129. The water/steam cycle 24 of the gas turbine and steam turbine
installation 1 therefore includes, in the exemplary embodiment,
three pressure stages 50, 90, 120. As an alternative, however,
fewer pressure stages, in particular two, can be provided.
[0044] The gas turbine installation 1a is configured for operation
with a gasified synthesis gas SG which is generated by the
gasification of a fossil fuel B. Gasified coal or gasified oil can,
for example, be provided as the synthesis gas. For this purpose,
the combustion chamber 6 of the gas turbine 2 is connected at its
inlet end via a fuel line 130 to a gasification device 132. Coal or
oil, as the fossil fuel B, can be supplied to the gasification
device 132 via a charge system 134.
[0045] In order to make available the oxygen O.sub.2 necessary for
the gasification of the fossil fuel B, an air separation unit 138
is connected via an oxygen line 136 upstream of the gasification
device 132. At its inlet end, the air separation unit 138 can be
subjected to a partial flow T of the air compressed in the air
compressor 4. For this purpose, the air separation unit 138 is
connected, at its inlet end, to an extraction air line 140 which
branches off from the compressed air line 8 at a branch location
142. A further air line 143, into which is connected an additional
air compressor 144, also opens into the extraction air line
140.
[0046] In the exemplary embodiment, the total airflow L flowing to
the air separation unit 138 is made up of the partial flow T
branched off from the compressed air line 8 and the airflow
delivered by the additional air compressor 144. Such a connection
concept is also designated a partially integrated installation
concept. In an alternative embodiment, the so-called fully
integrated installation concept, it is possible to dispense with
the further air line 143 and also with the additional air
compressor 144 so that the complete air feed to the air separation
unit 138 takes place through the use of the partial flow T
extracted from the compressed air line 8.
[0047] The nitrogen N.sub.2 obtained, in addition to the oxygen
O.sub.2, in the air separation unit 138 during the separation of
the airflow L is supplied to a mixing appliance 146, via a nitrogen
line 145 connected to the air separation unit 138, and is there
mixed with the synthesis gas SG. The mixing appliance 146 is then
configured for a particularly uniform and streak-free mixing of the
nitrogen N.sub.2 with the synthesis gas SG.
[0048] The synthesis gas SG flowing away from the gasification
device 132 passes initially, via the fuel line 130, into a crude
gas waste-heat steam generator 147 in which, through the use of
heat exchange with a flow medium, cooling of the synthesis gas SG
takes place. High-pressure steam generated during this heat
exchange is supplied, in a manner not shown in any more detail, to
the high-pressure stage 50 of the water/steam cycle 24.
[0049] Behind the crude gas waste-heat steam generator 147 and
before the mixing appliance 146, viewed in the flow direction of
the synthesis gas SG, a dust-removal device 148 for the synthesis
gas SG and a desulphurization installation 149 are connected into
the fuel line 130. In an alternative configuration, a soot-washing
appliance can also be provided instead of the dust-removal device
148, in particular in the case of the gasification of oil as the
fuel.
[0050] For particularly low pollutant emission during the
combustion of the gasified fuel in the combustion chamber 6, the
gasified fuel is loaded with water vapor before it enters into the
combustion chamber 6. This can take place in a thermally
particularly advantageous manner in a saturator system. For this
purpose, a saturator 150, in which the gasified fuel is guided in
counterflow relative to the heated water flow W (also referred to
as saturator water), is connected into the fuel line 130. The
saturator water or the water flow W then circulates in a saturator
cycle 152, which is connected to the saturator 150 and into which a
circulating pump 154 is connected. A feed line 158 is connected to
the saturator cycle 152 to compensate for losses of saturator water
occurring during the saturation of the gasified fuel.
[0051] The secondary side of a heat exchanger 159 acting as a crude
gas/mixed gas heat exchanger is connected into the fuel line 130
behind the saturator 150, viewed in the flow direction of the
synthesis gas SG. The primary side of the heat exchanger 159 is
then likewise connected into the fuel line 130 at a position in
front of the dust removal installation 148, so that the synthesis
gas SG flowing to the dust removal installation 148 transfers a
part of its heat to the synthesis gas SG flowing out of the
saturator 150. The guidance of the synthesis gas SG via the heat
exchanger 159 before it enters the desulphurization installation
149 can then also be provided in a modified connection concept
relative to the other components. In the case of the connection of
a soot-washing device, in particular, the heat exchanger can
preferably be provided on the crude gas side downstream of the
soot-washing device.
[0052] The secondary side of a further heat exchanger 160, whose
primary side can be heated by feed water or also by steam, is
connected into the fuel line 130 between the saturator 150 and the
heat exchanger 159. Particularly reliable preheating of the
synthesis gas SG flowing to the combustion chamber 6 of the gas
turbine 2, even in the case of different operating conditions of
the gas turbine and the steam turbine installation 1, is then
ensured by the heat exchanger 159, which is configured as a crude
gas/clean gas heat exchanger, and by the heat exchanger 160.
[0053] In order to subject the synthesis gas SG flowing to the
combustion chamber 6 to steam, if required, a further mixing
appliance 161 is, in addition, connected into the fuel line 130.
Medium-pressure steam can be supplied to this further mixing
appliance 161 via a steam line (not shown) in order, in particular,
to ensure reliable gas turbine operation in the case of operational
faults.
[0054] In order to cool the partial flow T of compressed air, also
designated as tapped air or extracted air, to be supplied to the
air separation unit 138, the primary side of a heat exchanger 162
is connected into the extraction air line 140, the secondary side
of this heat exchanger 162 being configured as a medium-pressure
evaporator for a flow medium S'. The heat exchanger 162 is
connected to a water/steam drum 164, which is configured as a
medium-pressure drum, in order to form an evaporator circuit 163.
The water/steam drum 164 is connected to the medium-pressure drum
96 associated with the water/steam circuit 100 by lines 166, 168.
As an alternative, the secondary side of the heat exchanger 162 can
also be directly connected to the medium-pressure drum 96. In the
exemplary embodiment, the water/steam drum 164 is therefore
directly connected (see III, IV) to the heating surface 98, which
is configured as a medium-pressure evaporator. In addition, a feed
water line 170 is connected to the water/steam drum 164 in order to
top up evaporated flow medium S'.
[0055] A further heat exchanger 172, whose secondary side is
configured as the low-pressure evaporator for a flow medium S", is
connected into the extraction air line 140 after the heat exchanger
162, viewed in the flow direction of the partial flow T of
compressed air. The heat exchanger 172 is then connected to a
water/steam drum 176, which is configured as a low-pressure drum,
in order to form an evaporator circuit 174. In the exemplary
embodiment, the water/steam drum 176 is connected (see I, II) to
the low-pressure drum 122, which is associated with the water/steam
circuit 126, via lines 178, 180 and is therefore directly connected
to the heating surface 124, which is configured as a low-pressure
evaporator. As an alternative, however, the water/steam drum 176
can also be connected in another suitable manner, wherein it is
then possible to supply steam taken from the water/steam drum 176
to an auxiliary consumption unit as process steam and/or as steam
for heating purposes. In a further alternative embodiment, the
secondary side of the heat exchanger 172 can also be directly
connected to the low-pressure drum 122. The water/steam drum 176
is, in addition, connected to a feed water line 182.
[0056] Each of the evaporator circuits 163, 174 can be configured
as a forced circulation system, the circuit of the flow medium S'
or S" being ensured by a circulating pump and the flow medium S',
S" being at least partially evaporated in a heat exchanger 162 or
172 configured as an evaporator. In the exemplary embodiment,
however, both the evaporator circuit 163 and the evaporator circuit
174 are respectively configured as natural circulation systems, the
circulation of the flow medium S' or S" being ensured by the
pressure differences arising during the evaporation process and/or
by the geodetic configuration or positioning of the respective heat
exchanger 162 or 172 and the respective water/steam drum 164 or
176. In this configuration, only a comparatively modestly
dimensioned circulating pump (not shown) is respectively connected
into the evaporator circuit 163 or into the evaporator circuit 174
for starting the system.
[0057] In order to couple heat into the saturation cycle 152 and
therefore for setting a temperature in the water flow W sufficient
for charging the synthesis gas SG with water vapor, a
saturator-water heat exchanger 184 is provided which can be
subjected on the primary side to feed water S from the feed water
tank 46. For this purpose, the primary side of the saturator-water
heat exchanger 184 is connected (see V), at the inlet end, via a
line 186 to the branch line 84 and, at the outlet end, via a line
188 (see VI) to the feed water tank 46. The saturator-water heat
exchanger 184 is then connected on the secondary side downstream,
viewed in the flow direction of the water flow W, of the inlet of
the feed line 158 into the saturator cycle 152.
[0058] For additional heating of the water flow W, if required, an
additional heat exchanger 189 is connected into the saturator cycle
152 in the exemplary embodiment. The additional heat exchanger 189
is then subjected on the primary side (see VII, VIII) to preheated
feed water from the medium pressure stage 90 of the water/steam
cycle 24. The additional heat exchanger 189 can, however, also be
dispensed with--depending on the specified emission values and/or
combustion gas temperatures.
[0059] A further heat exchanger 190 is connected into the line 188
for reheating the cooled feed water S flowing from the
saturator-water heat exchanger 184, this further heat exchanger 190
being connected on the primary side downstream of the heat
exchanger 172 in the extraction air line 140. Such a configuration
can achieve a particularly high heat recovery from the tapped
(extracted) air and, therefore, a particularly high efficiency of
the gas turbine and steam turbine installation 1.
[0060] A cooling air line 192, through the use of which a partial
quantity T' of the cooled partial flow T can be supplied as cooling
air to the gas turbine 2 for blade cooling, branches off from the
extraction air line 140 between the heat exchanger 172 and the heat
exchanger 190, viewed in the flow direction of the partial flow
T.
[0061] Subjecting the saturator-water heat exchanger 184 to feed
water S from the water/steam cycle 24 of the steam turbine 20
permits reliable operation of the saturator 150 independent of the
operating condition of the air separation unit 138. The overall
efficiency of the gas turbine and steam turbine installation 1 then
benefits particularly from the fact that reheating of the feed
water S cooled in the saturator-water heat exchanger 184 takes
place in the additional heat exchanger 190. The invention thus
ensures a reliable setting of the final temperature of the partial
flow T flowing as tapped air to the air separation unit 138 and
also ensures a simultaneous recovery of the heat carried in this
partial flow for the energy generation process of the gas turbine
and steam turbine installation 1.
* * * * *