U.S. patent application number 13/496115 was filed with the patent office on 2012-07-05 for steam power plant.
Invention is credited to Carsten Graeber, Georg Haberberger, Michael Wechsung.
Application Number | 20120167568 13/496115 |
Document ID | / |
Family ID | 42782044 |
Filed Date | 2012-07-05 |
United States Patent
Application |
20120167568 |
Kind Code |
A1 |
Graeber; Carsten ; et
al. |
July 5, 2012 |
STEAM POWER PLANT
Abstract
A steam power plant including a number of partial turbines is
provided. Each partial turbine is permeated by steam, an overflow
line disposed between a first partial turbine and a second partial
turbine and an intermediate superheater in the overflow line. A
bleeder line for extracting steam is thereby fluidically connected
to the first partial turbine after the expansion stage, prior to
the intermediate superheater. An expansion device is further
provided, into which the bleeder line opens, and a consumer is
connected via a process steam line of the expansion device.
Inventors: |
Graeber; Carsten; (Erlangen,
DE) ; Haberberger; Georg; (Bubenreuth, DE) ;
Wechsung; Michael; (Mulheim an der Ruhr, DE) |
Family ID: |
42782044 |
Appl. No.: |
13/496115 |
Filed: |
September 17, 2010 |
PCT Filed: |
September 17, 2010 |
PCT NO: |
PCT/EP2010/063661 |
371 Date: |
March 14, 2012 |
Current U.S.
Class: |
60/676 |
Current CPC
Class: |
F01K 7/22 20130101; Y02E
20/14 20130101; Y02E 20/32 20130101; F01K 17/04 20130101; Y02E
20/326 20130101 |
Class at
Publication: |
60/676 |
International
Class: |
F01K 13/00 20060101
F01K013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 23, 2009 |
EP |
09171049 |
Claims
1-10. (canceled)
11. A steam power plant, comprising: a plurality of turbine
sections including a first turbine section and a second turbine
section, through which steam flows in each case; a crossover line,
which is arranged between the first turbine section and the second
turbine section; and a reheater in the crossover line, wherein a
bleed line for steam extraction is connected to the first turbine
section downstream of an expansion stage, fluidically upstream of
the reheater, in that provision is made for the expansion device
which is designed as an expansion turbine and into which leads the
bleed line, wherein a consumer is connected via a process steam
line to the expansion device, and wherein the expansion turbine
including the plurality of turbine sections is arranged on a common
shaft.
12. The steam power plant as claimed in claim 11, wherein the
consumer is designed as a flue gas scrubber.
13. the steam power plant as claimed in claim 12, wherein the flue
gas scrubber is a CO.sub.2 separator.
14. The steam power plant as claimed in claim 11, wherein the
consumer is designed as a fuel treatment facility.
15. The steam power plant as claimed in claim 11, wherein the
expansion device is designed to essentially provide the total
required volume of steam for the consumer.
16. The steam power plant as claimed in claim 11, wherein the
expansion turbine is of double-flow design with two asymmetrical
expansion sections, and wherein the bleed line leads into a first
expansion section and a crossover line from a turbine section,
which is routed via a reheater, leads into a second expansion
section.
17. The steam power plant as claimed in claim 11, wherein the
expansion turbine comprises additional bleed points for process
steam.
18. The steam power plant as claimed in claim 11, wherein a
high-pressure turbine section and an intermediate-pressure turbine
section are included and are interconnected via the crossover line
having reheaters, and wherein the bleed line is connected to the
high-pressure turbine section.
19. The steam power plant as claimed in claim 18, wherein the bleed
line is connected to the high-pressure turbine section via the
crossover line.
20. The steam power plant as claimed in claim 11, wherein a
high-pressure turbine section, a first intermediate-pressure
turbine section, a second intermediate-pressure turbine section are
included, wherein the first intermediate-pressure turbine section
and the second intermediate-pressure turbine section are
interconnected via the crossover line having reheaters, and wherein
the bleed line is connected to the first intermediate-pressure
turbine section.
21. The steam power plant as claimed in claim 20, further
comprising a low-pressure turbine section.
22. The steam power plant as claimed in claim 20, wherein the bleed
line is connected to the first intermediate-pressure turbine
section via the crossover line.
23. The steam power plant as claimed in claim 11, further
comprising a steam boiler and on the exhaust gas side is connected
via an exhaust gas line to the consumer.
24. The steam power plant as claimed in claim 23, wherein a gas
turbine is included and on the exhaust gas side is connected to the
steam boiler.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is the US National Stage of International
Application No. PCT/EP2010/063661, filed Sep. 17, 2010 and claims
the benefit thereof. The International Application claims the
benefits of European Patent Office application No. 09171049.1 EP
filed Sep. 23, 2009. All of the applications are incorporated by
reference herein in their entirety.
FIELD OF INVENTION
[0002] The invention refers to a steam power plant, comprising a
number of turbine sections, through which steam can flow in each
case, a crossover line, which is arranged between a first turbine
section and a second turbine section, and a reheater in the
crossover line.
BACKGROUND OF INVENTION
[0003] A steam power plant of the type referred to in the
introduction is to be gathered from EP 1 744 032 A1, for example.
The steam power plant, in this case designed as a combined gas and
steam power plant (CCPP), comprises a number of turbine sections
which are designed for different pressures and through which steam
flows. The steam, for example after exiting from a turbine section
which is designed as a high-pressure turbine, is directed via a
crossover line into a reheater. A further crossover line is
arranged between an intermediate-pressure turbine and a
low-pressure turbine. This crossover line is equipped with a valve
for the extraction of heating steam and process steam. The process
steam is fed via a steam line to an engineering plant or to an
industrial operation.
[0004] Especially in the case of steam power plants with very high
efficiency requirements, suitable ways are sought of suitably
extracting large volumes of steam. Large volumes of steam are
required for example for district heat extraction, for the
treatment of fuel, particularly such as brown coal drying, or for
flue gas scrubbing, particularly such as CO.sub.2 separation. These
consumers, in addition to the large volumes of steam which can be
up to half the volume of steam fed to a low-pressure turbine
section in a conventional steam power plant, require the steam,
moreover, at a relatively low temperature level of 100.degree. C.
to 150.degree. C. close to the condensation temperature.
[0005] According to EP 1 744 032 A1, steam extraction is carried
out from a crossover line between two turbine sections, especially
between an intermediate-pressure steam turbine and a low-pressure
steam turbine. In this case, to remove large volumes of steam
would, however, seriously reduce the efficiency of the steam power
plant in an undesirable way.
SUMMARY OF INVENTION
[0006] For a steam power plant, it is the object of the invention
to disclose a steam treatment for a specific consumer with high
steam requirement, wherein with costs which are as low as possible
the overall efficiency remains as high as possible.
[0007] This object of the invention is achieved according to the
invention by means of a steam power plant with the feature
combination according to the claims.
[0008] Therefore, the steam power plant comprises a number of
turbine sections, through which steam can flow in each case, a
crossover line, which is arranged between a first turbine section
and a second turbine section, and a reheater in the crossover line.
In this case, a bleed line for steam extraction is connected to the
first turbine section downstream of the expansion stage,
fluidically upstream of the reheater. Provision is made for an
expansion device into which leads the bleed line, and for a
consumer which is connected via a process steam line to the
expansion device.
[0009] In a first step, the invention is based on the fact that
previously a volume of steam was customarily extracted from
crossover lines downstream of a reheater. Superheated steam,
however, provides higher temperatures than are necessary for the
mentioned consumers, particularly such as a flue gas scrubber or
for a fuel treatment facility, and therefore provides an exergy
surplus. The surplus of exergy, therefore, is lost without being
utilized, as a result of which the efficiency of the steam power
plant is reduced.
[0010] The invention solves this problem by the steam being
extracted upstream of the reheater via a bleed line. Such steam has
a usable temperature level for connected consumers. Since the
extracted steam leaves the steam power plant without unnecessary
exergy losses, the overall efficiency of the steam power plant can
be maintained at a higher level compared with the previously known
solution. In other words, the invention makes provision for
extracting the steam upstream of, or from, the so-called cold
reheat line, this being the feed line to the reheater. In this
case, the invention is also to comprise such developments in which
the required steam is essentially or predominantly extracted from
the crossover line upstream of the reheater, and wherein a further,
smaller, proportion of steam is taken, for example, from the
crossover line downstream of the reheater. This can be altogether
more cost-effective for a specific consumer, taking into
consideration the overall system, or, in a given case, can lead to
higher overall efficiency.
[0011] In a further step, the invention makes provision for an
expansion device, by means of which the extracted steam is expanded
to a corresponding pressure level upstream of the forwarding line
to a consumer. As a result of the expansion, the temperature of the
steam is also reduced and the conditions which are required for a
consumer can be specifically established. The steam can especially
be set exactly to the level which is usable by the consumer,
performing work. An expansion device therefore offers the
additional advantage of improving the overall efficiency of the
steam power plant as a result of the expansion of the steam,
performing work for the overall system.
[0012] A steam power plant is the predominant type of construction
of a power plant for the conventional generation of electric energy
from fossil fuels, in which the thermal energy from steam is
utilized in a steam turbine. For operating a steam turbine, steam
is heated in a steam boiler and introduced into the steam turbine.
There, the steam is expanded. The work which is released during the
expansion is delivered to a generator, for example, which is
connected to the turbine. The steam boiler is fired with
conventional fuels, such as natural gas or coal. In the case of a
combined gas and steam plant (CCPP), the exhaust gas of the gas
turbine is fed to a waste heat steam boiler for steam preparation.
By utilizing the residual heat which is contained within the
exhaust gas flow of the gas turbine, a particularly high level of
overall efficiency can be achieved in such a combined gas and steam
power plant, and therefore a saving in fuel can also be made. This
is of great interest with regard to the issues of protection of the
environment.
[0013] A steam power plant usually comprises a plurality of turbine
sections which are designed in each case for different pressures.
In this case, for example high-pressure (HP) turbine sections,
intermediate-pressure (IP) turbine sections and low-pressure (LP)
turbine sections connected in series are customary. It is also
possible that a steam turbine has a plurality of turbine sections
which are designed for the same pressures.
[0014] Inside a steam turbine, the steam from a turbine section at
high pressure (for example an HP turbine section) is expanded in
the direction of a turbine section with the lowest pressure (for
example an LP turbine section). The number of expansion stages,
that is to say the number of series-connected turbine sections, can
be different in this case, depending upon application and upon the
connected consumer. The individual turbine sections can be of
single-flow or multiflow design.
[0015] The steam power plant disclosed here comprises a crossover
line, having a reheater, which is arranged between a first turbine
section and a second turbine section. Via such a crossover line,
for example the steam expanded in a high-pressure turbine section
is directed into an intermediate-pressure turbine section in order
to be further expanded there.
[0016] In the process, the reheater superheats again the previously
expanded steam which discharges from the first turbine section. The
superheated steam is finally directed into the second turbine
section with a lower pressure level. The steam is again expanded
there. It is possible to provide a plurality of reheaters in a
steam power plant. A steam power plant can be designed with one
reheater, or with a plurality of reheaters, depending upon the
number of turbine sections.
[0017] The bleed line is connected to the first turbine section
downstream of the expansion stage, in fact fluidically upstream of
the reheater. By means of the bleed line, process steam can be
extracted from the turbine system. The bleed line can basically be
connected directly to the turbine or can be branched from the feed
line to the reheater.
[0018] The expansion device is connected on the outlet side, via a
process steam line, to the consumer. The process steam expanded in
the expansion device, and therefore set at the required level, is
directed via the process steam directly to the consumer. The
expansion device is preferably designed to deliver the essentially
total required volume of steam to the consumer.
[0019] In accordance with the aforesaid specific consumers, which
require enormously large volumes of steam at a relatively low
temperature level, the expansion device is especially designed for
expanding large volumes of steam from the delivered pressure level
from the cold reheat line to pressures of between about 1.5 and 5
bar at a temperature level of between about 100.degree. C. and
150.degree. C. For example, a flue gas scrubber, especially for
CO.sub.2 separation, requires a pressure of about 2 bar at such a
temperature level. A fuel treatment facility, especially a brown
coal drier, requires pressures of between 3 bar and 5 bar.
[0020] In the case of the design of the consumer as a flue gas
scrubber, exhaust gas, also referred to as flue gas, for example
from the firing system of the steam boiler, is directed through a
corresponding fluid, wherein a gas component which is to be
separated goes into solution. The residual gas is directed into the
exhaust air by means of the flue gas scrubber. The gas component,
which is in solution, is thermally driven out of the fluid and, for
example, fed to a storage facility or the like or permanently
integrated elsewhere. For the thermal removal of the dissolved gas
component, the process steam is required. The flue gas scrubber is
especially designed for separating CO.sub.2 from the flue gas. The
separated. CO.sub.2 is fed to a place of storage, for example in
underground storage facilities.
[0021] For separating CO.sub.2 and other acidic gas components from
the flue gas, a so-called amine scrubber, for example, is used,
wherein the flue gas is directed through an aqueous amine solution.
In the process, the acidic components, especially CO.sub.2, go into
solution. The residual components are directed into the exhaust
air. The solution is subsequently heated by means of the process
steam to between 100.degree. C. and 150.degree. C., as a result of
which the CO.sub.2 emerges again from the solution. The residual
gases possibly remain in the solution. The CO.sub.2 can
subsequently be compressed and then, for example, pumped into
storage facilities in the ground.
[0022] The flue gas scrubber is designed especially to extract the
required heat, for expelling the CO.sub.2, from the supplied
process steam, which discharges this possibly by condensing. The
steam condensate is fed back into the steam cycle.
[0023] The high cost for separating CO.sub.2 from the exhaust gases
of a power plant, especially of a steam power plant--wherein large
volumes of steam are extracted, reducing the efficiency,--is
necessary taking into consideration overall environmentally
relevant effects. A steam power plant equipped in such a way,
compared with conventional plants, fulfills the stipulated
emissions requirements, which are becoming more stringent, in
relation to this.
[0024] In the case of the design of the consumer as a flue gas
scrubber, the steam power plant comprises an exhaust gas line which
leads into the consumer. By means of such an exhaust gas line, the
exhaust gas is fed to the consumer, for example directly from the
firing system of the steam boiler, or as exhaust gas of a gas
turbine from a waste heat steam boiler.
[0025] In another development, the consumer of large volumes of
steam is constructed as a fuel treatment facility. In this case,
the heat of the process steam is used for removal of residual
moisture from brown coal, for example.
[0026] The expansion device can especially be designed separately
for the turbine sections. In this case, the possibility exists of
retrofitting an existing steam turbine or an existing steam power
plant. The expansion device, however, is advantageously an
integrated component part of the turbine generator set of the steam
power plant. This solution is especially ideal in the case of a new
design of a steam power plant since less space is required overall,
and such an arrangement can possibly contribute positively to the
overall efficiency. However, a separate solution also offers the
great advantage that the system parts downstream of the steam bleed
point can be designed more cost effectively. Since a substantial
proportion of steam is extracted for the said consumer, pipelines
downstream of the bleed point, especially for a crossover line
between an intermediate-pressure turbine section and a low-pressure
turbine section, can be designed with a smaller cross section than
normal, as a result of which considerable cost advantages ensue. In
the same way, heating surfaces downstream of the bleed point can be
designed smaller than in the case of conventional types of
construction, which again is associated with cost advantages.
[0027] The expansion device is preferably designed as an expansion
turbine. As a result of such a design, it becomes easily possible
to still utilize existing energy surplus for the performing of work
for the overall system. Via the expansion of the extracted steam, a
shaft in particular, which can be connected to a generator, is
driven.
[0028] The expansion turbine is preferably operated in
back-pressure mode. The expansion end downstream of the expansion
turbine then corresponds to the required process steam pressure.
Therefore, the required pressure level and temperature level can
ideally be provided for the consumer.
[0029] If the expansion turbine in an advantageous development is
not constructed as a separate turbine, but is arranged on a common
shaft with the turbine sections, then the work produced is
delivered directly to the overall system.
[0030] The design of the expansion device as an expansion turbine
furthermore offers the great advantage that the pressure level for
the consumer can ideally be set by control of the turbine, in fact
within broad limits regardless of the pressure level of the
inflowing steam. In particular, pressure fluctuations of the
inflowing steam can also easily be compensated by corresponding
control of the turbine.
[0031] The expansion turbine expediently has additional bleed
points. For example, a regenerative feed-water preheater, or a
plurality of feed-water preheaters, can be fed as a result of
this.
[0032] A high-pressure turbine section and an intermediate-pressure
turbine section are advantageously included and interconnected via
the crossover line having reheaters, wherein the bleed line is
connected to the high-pressure turbine section, especially via the
crossover line. In this case, the extracted steam is expanded
downstream of the high-pressure turbine section in a separate
expansion step to the corresponding pressure level of a connected
consumer. The process steam is not directed via a reheater upstream
of the extraction. The downstream system parts are designed more
cost-effectively corresponding to the reduced volume of steam.
[0033] In a further advantageous development, a high-pressure
turbine section, a first intermediate-pressure turbine section, a
second intermediate-pressure turbine section and, if necessary, a
low-pressure turbine section, or a plurality of low-pressure
turbine sections, are included, wherein the first
intermediate-pressure turbine section and the second
intermediate-pressure turbine section are interconnected via the
crossover line having a second reheater, and wherein the bleed line
is connected to the first intermediate-pressure turbine section,
especially via the crossover line. In this case, the volume of
steam which is required for a CO.sub.2 separation facility, for
example, can be extracted downstream of the first
intermediate-pressure turbine section and be expanded especially in
an expansion turbine to the desired pressure level.
[0034] Preferably included is a steam boiler, which is connected on
the exhaust gas side, via the exhaust gas line, to the consumer.
The steam boiler provides exhaust gases from the combustion system
which are fed to a CO.sub.2 separation facility. As a result of the
connection between the steam boiler and the consumer, the
possibility is presented of clearing the exhaust gas of CO.sub.2
before being emitted into the atmosphere. Such a treatment of the
exhaust gas offers the possibility of designing a steam power plant
in an especially environmentally caring and energy efficient
manner. In a further development, the exhaust gas of a gas turbine
is ducted for heating steam in a waste heat steam boiler and is
directed from there to the consumer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Exemplary embodiments of the invention are explained in more
detail in the following text with reference to a drawing. In this
case, in the drawing
[0036] FIG. 1 schematically shows a steam power plant with a number
of turbine sections and a bleed line downstream of the
high-pressure (HP) expansion stage, wherein extracted steam is
expanded in a separate expansion turbine,
[0037] FIG. 2 schematically shows a steam power plant with a number
of turbine sections and a bleed line downstream of a high-pressure
(HP) expansion stage, wherein extracted steam is expanded in an
expansion turbine which is integrated in the turbine generator
set,
[0038] FIG. 3 schematically shows a steam power plant with a number
of turbine sections and a bleed line downstream of a first
intermediate-pressure (IP) expansion stage, wherein extracted steam
is expanded in a separate expansion turbine, and
[0039] FIG. 4 schematically shows a steam power plant with a number
of turbine sections and a bleed line downstream of a first
intermediate-pressure (IP) expansion stage, wherein extracted steam
is expanded in a double-flow expansion turbine which is integrated
in the turbine generator set.
[0040] The same components in the figures retain the same
designations in each case here.
DETAILED DESCRIPTION OF INVENTION
[0041] FIG. 1 shows a steam power plant 1 with a number of turbine
sections which are designed for different pressures. The turbine
sections are allocated in series to a common shaft 5.
[0042] For operation, water is heated in a steam boiler 7 and steam
is produced via a live-steam superheater 9. The superheated steam
is introduced as operating steam, via a piping arrangement, into a
high-pressure turbine section 13, where the steam is expanded.
After expansion in the high-pressure turbine section 13, a portion
of the steam is directed, via a first crossover line 14, into a
reheater 15, reheated there, and then directed into a double-flow
intermediate-pressure turbine section 17.
[0043] Here, the steam expands again to a predetermined, now lower
pressure level.
[0044] Following this, the steam, which is expanded in the
intermediate-pressure turbine section 17 to the lower pressure
level, is directed, via an associated second crossover line 21,
into an also double-flow low-pressure turbine section 25.
[0045] A generator 29 is driven via the common shaft 5 for electric
power generation. The steam, expanded and cooled, leaving the
low-pressure turbine section 25, flows into a condenser 31 where it
condenses as a result of heat transfer to the environment and
accumulates as liquid water. Via a condensate pump 33 and a
preheater 35, the water is temporarily stored in a feed-water tank
37 and then fed again to the steam boiler 7 via a feed-water pump
39.
[0046] Downstream of the expansion stage, a bleed line 41 is
connected to the high-pressure turbine section 13 downstream of its
expansion stage, in fact fluidically upstream of the reheater 15.
Via this bleed line 41, steam which is required for a consumer 49
is extracted from the system downstream of the expansion in the
high-pressure turbine section 13.
[0047] The bleed line 41 leads into an expansion device 43 which is
therefore connected to the high-pressure turbine section 13. The
expansion device 43 is designed as a separate expansion turbine 44
to which is connected a second generator 45. Inside the expansion
turbine 44, the extracted steam is expanded ideally to a level
(pressure, temperature) desired for the consumer 49, performing
work for the overall system. Instead of the generator, a suitable
consumer for mechanical energy can also be arranged or
connected.
[0048] From the expansion turbine 44, the expanded process steam is
forwarded directly to the consumer 49 via a process steam line 47.
This consumer is designed as a fuel treatment facility or as a flue
gas treatment facility, for example. The separate expansion turbine
44 is operated in back-pressure mode.
[0049] The expansion end corresponds as far as possible in this
case directly to the required process steam pressure so that the
expansion turbine 44 ideally provides the required level of
pressure and temperature for the connected consumer 49.
[0050] FIG. 2 shows a further development of a steam power plant 61
with a number of turbine sections.
[0051] As also in FIG. 1, the turbine generator set is operated by
means of superheated steam from a steam boiler 7. The steam finds
its way from the steam boiler 7 into the live-steam superheater 9
and then, via a piping arrangement, into the high-pressure turbine
section 13.
[0052] In contrast to FIG. 1, the expansion device 43 of the steam
power plant is now, however, not arranged separately from the
turbine generator set but allocated to the common shaft 5 as a
correspondingly designed expansion turbine 64. Via a bleed point A
from the first crossover line 14, extracted steam is fed to the
expansion turbine 64 and expanded to the level required by the
consumer 49, which is connected on the outlet side via the process
steam line 47, performing work for the overall system.
[0053] The consumer 49 in this case is designed as a flue gas
scrubber for CO.sub.2 separation from the exhaust gases of the
firing system 65 of the steam boiler 7. Correspondingly, an exhaust
gas line 51 from the firing system 65 leads into the consumer 49.
The resulting CO.sub.2, as described previously, is removed from
the exhaust gases and stored.
[0054] In FIG. 3, a third development of a steam power plant 71 is
to be seen. The steam power plant 71, as also in FIGS. 1 and 2, is
designed as a steam power plant with a number of turbine sections.
The operation of the steam power plant 71 can be gathered in
accordance with the preceding embodiments.
[0055] As in FIG. 1, the expansion device 43 in the steam power
plant 71 is designed as a separate expansion turbine 44. In
contrast to FIG. 1, the expansion turbine 44, however, is connected
via the bleed line 41 to the first intermediate-pressure turbine
section 17 downstream of the expansion stage.
[0056] The operating steam, after expansion in the high-pressure
turbine section 13, is directed via a first crossover line 14 and
via the first reheater 15 into the first intermediate-pressure
turbine section 17 and expanded there. Via the third crossover line
73, the expanded steam is directed downstream of the first
intermediate-pressure turbine section 17 through a second reheater
75 and from there is led into a second intermediate-pressure
turbine section 19. Via the second crossover line 21, the steam
expanded in the second intermediate-pressure turbine section 19 is
directed into the double-flow low-pressure turbine section 25. From
there, the steam is further processed in accordance with the
processes described in FIGS. 1 and 2.
[0057] According to FIG. 3, provision is made to feed the exhaust
gases of a gas turbine 53 to the boiler 7 for steam generation.
From there, the exhaust gases flow via the exhaust gas line 51 into
the consumer 49 which in the present case is again designed as a
flue gas scrubber.
[0058] The steam power plant 81 according to FIG. 4 comprises a
single-flow intermediate-pressure turbine section 20, from which
discharging, expanded steam is led via the third crossover line 73
and via the second reheater 75 into an expansion turbine 44 which
is integrated into the turbine generator set.
[0059] The expansion turbine 44, which is allocated to the common
shaft 5, is designed, according to FIG. 4, as an asymmetrical
turbine section which has a first expansion section 77 and a second
expansion section 78. The second expansion section 78 is designed
as an intermediate-pressure turbine. After expansion, the steam
flows via the crossover line 21 into the double-flow low-pressure
turbine section 25. The first expansion section 77 is connected on
the inlet side, via the bleed line 41, to the third crossover line
73. From this, steam is extracted for the consumer 49. The first
expansion section 77 expands the extracted steam for the consumer
49 to the required level, performing work for the overall system.
The expanded steam is fed via the process steam line 47 to the
consumer 49.
[0060] The asymmetrical expansion turbine 44 according to FIG. 4
can also be used as a separate expansion device in isolation from
the turbine generator set.
* * * * *