U.S. patent application number 15/392703 was filed with the patent office on 2018-06-28 for steam turbine with steam storage system.
The applicant listed for this patent is General Electric Company. Invention is credited to Theres Cuche, Julia Maria Kirchner, Kevin Morris.
Application Number | 20180179915 15/392703 |
Document ID | / |
Family ID | 60574419 |
Filed Date | 2018-06-28 |
United States Patent
Application |
20180179915 |
Kind Code |
A1 |
Kirchner; Julia Maria ; et
al. |
June 28, 2018 |
STEAM TURBINE WITH STEAM STORAGE SYSTEM
Abstract
A steam turbine system including a steam source for generating a
steam flow, a high pressure turbine providing a first steam
exhaust, a low pressure turbine fluidly coupled to the high
pressure turbine, and, a steam storage system having an inlet for
receiving a portion of the first steam exhaust from the high
pressure steam turbine and storing in the steam storage system, the
steam storage system having an output with a pressure relief valve
for discharging a second steam exhaust to the low pressure
turbine.
Inventors: |
Kirchner; Julia Maria;
(Gernsheim, DE) ; Cuche; Theres; (Ehrendingen,
CH) ; Morris; Kevin; (Dublin, IE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company |
Schenectady |
NY |
US |
|
|
Family ID: |
60574419 |
Appl. No.: |
15/392703 |
Filed: |
December 28, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01K 23/10 20130101;
F01K 3/267 20130101; F01K 7/02 20130101; F01K 3/185 20130101; Y02E
20/16 20130101; F01K 11/02 20130101; F01K 23/06 20130101; F01K 7/16
20130101; F01K 7/28 20130101; F01K 1/18 20130101; F01K 7/26
20130101; F01K 7/18 20130101; F01K 7/20 20130101; F01K 3/008
20130101; F01K 3/04 20130101 |
International
Class: |
F01K 3/18 20060101
F01K003/18; F01K 11/02 20060101 F01K011/02; F01K 1/18 20060101
F01K001/18 |
Claims
1. A steam turbine system, comprising: a steam source for
generating a steam flow; a high pressure turbine providing a first
steam exhaust; a low pressure turbine fluidly coupled to the high
pressure turbine; a steam storage system having an inlet for
receiving a portion of the first steam exhaust from the high
pressure steam turbine and storing in the steam storage system, the
steam storage system having an output with a pressure relief valve
for discharging a second steam exhaust to the low pressure
turbine.
2. The steam turbine system of claim 1, wherein the steam source
includes a first superheater and a second superheater, the steam
turbine system further comprising an interstage desuperheater
operatively arranged between the first and second superheaters.
3. The steam turbine system of claim 1, further comprising a
desuperheater between the first exhaust of the high pressure steam
turbine and the inlet of the steam storage system.
4. The steam turbine system of claim 1, further comprising a heat
exchanger operatively coupled between the first exhaust of the high
pressure steam turbine and the inlet of the steam storage
system.
5. The steam turbine system of claim 4, wherein the steam source is
a heat recovery system generator (HRSG) having a low pressure
system, and the heat exchanger is configured to output into LP
steam from the low pressure system of the HRSG.
6. The steam turbine system of claim 1, further comprising an
intermediate pressure steam turbine fluidly coupled to the high
pressure steam turbine and the low pressure steam turbine.
7. The steam turbine system of claim 6, further comprising a second
desuperheater operatively coupled between the steam source and the
intermediate pressure steam turbine.
8. The steam turbine system of claim 7, wherein the steam source is
an HRSG having an intermediate pressure system, and the second
desuperheater is a water injection operatively coupled to the
intermediate pressure system and configured to control the
temperature of the inlet to the intermediate pressure steam
turbine.
9. The steam turbine system of claim 1, wherein the steam source is
a heat recovery steam generator (HRSG) and is operatively coupled
to a gas turbine.
10. The steam turbine system of claim 9, wherein there are a
plurality of HRSGs as steam sources operatively coupled to a
plurality of gas turbines, wherein the plurality of HRSGs generate
the steam flow.
11. The steam turbine system of claim 1, wherein the steam storage
system is a steam storage tank.
12. The steam turbine system of claim 1, wherein the steam storage
system includes a plurality of steam storage tanks.
13. A power plant, comprising: a steam turbine system, having: a
heat recovery steam generator (HRSG) for generating a steam flow; a
high pressure turbine providing a first steam exhaust; a low
pressure turbine fluidly coupled to the high pressure turbine; and,
a steam storage system having an inlet for receiving a portion of
the first steam exhaust from the high pressure steam turbine and
storing a storage steam, the steam storage system having an output
with a pressure relief valve for discharging a second steam exhaust
to the low pressure turbine.
14. The power plant of claim 13, wherein the HRSG includes a first
superheater and a second superheater, the steam turbine system
further comprising an interstage desuperheater operatively arranged
between the first and second superheaters.
15. The power plant of claim 13, further comprising a gas turbine
operatively coupled to the HRSG.
16. The power plant of claim 13, further comprising an intermediate
pressure turbine.
17. The power plant of claim 13, further comprising a second
desuperheater between the HRSG and the intermediate pressure
turbine.
18. A method, comprising: feeding a first portion of a first
exhaust steam from a high pressure steam turbine to a steam storage
system, and feeding a second portion of the steam to an HRSG;
storing the first portion of the steam in the steam storage system;
outputting, with a pressure relief valve, a steam flow from the
steam storage system to a low pressure steam turbine; and,
controlling the temperature of the exhaust steam from the steam
storage system by adding superheated steam from the first steam
exhaust, wherein the steam storage discharges superheated steam to
the low steam turbine.
19. The method of claim 18, further comprising running a combined
cycle power plant in part load, and providing an interstage
desuperheater between a first superheater and a second superheater
of the HRSG.
20. The method of claim 18, further comprising providing a heat
exchanger configured between the high pressure steam turbine and
the inlet of the steam storage system.
Description
BACKGROUND OF THE INVENTION
[0001] The disclosure relates generally to steam turbine systems,
and more particularly, to a steam turbine system with a steam
storage system.
[0002] In general, combined cycle power plants (CCPPs) operatively
couple a gas turbine system with a steam turbine system in order to
increase the plant's power output. Such plants' operating
capacities are a function of their design specifications, and
include certain limitations. One of these limitations is the
combined cost and time involved in re-starting the CCPP after a
shut down or interruption period.
BRIEF DESCRIPTION OF THE INVENTION
[0003] A first aspect of the disclosure provides a steam turbine
system including a steam source for generating a steam flow, a high
pressure turbine providing a first steam exhaust, a low pressure
turbine fluidly coupled to the high pressure turbine, and, a steam
storage system having an inlet for receiving a portion of the first
steam exhaust from the high pressure steam turbine and storing in
the steam storage system, the steam storage system having an output
with a pressure relief valve for discharging a second steam exhaust
to the low pressure turbine.
[0004] A second aspect of the disclosure provides a power plant
including a steam turbine system having a heat recovery steam
generator (HRSG) for generating a steam flow, a high pressure
turbine providing a first steam exhaust, a low pressure turbine
fluidly coupled to the high pressure turbine, and a steam storage
system having an inlet for receiving a portion of the first steam
exhaust from the high pressure steam turbine and storing a storage
steam, the steam storage system having an output with a pressure
relief valve for discharging a second steam exhaust to the low
pressure turbine.
[0005] A third aspect of the disclosure provides a method including
feeding a first portion of an exhaust steam from a high pressure
steam turbine to a steam storage system, and feeding a second
portion of the steam to an HRSG, storing the first portion of the
steam in the steam storage system, outputting, with a pressure
relief valve, a steam flow from the steam storage system to a low
pressure steam turbine, and, controlling the temperature of the
exhaust steam from the storage by adding superheated steam from the
first steam exhaust to discharge superheated steam to an LP steam
turbine.
[0006] The illustrative aspects of the present disclosure are
designed to solve the problems herein described and/or other
problems not discussed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] These and other features of this disclosure will be more
readily understood from the following detailed description of the
various aspects of the disclosure taken in conjunction with the
accompanying drawings that depict various embodiments of the
disclosure, in which:
[0008] FIG. 1 is a schematic view of portions of an illustrative
prior art combined cycle power generating system.
[0009] FIG. 2 is a perspective partial cut-away illustration of a
prior art steam turbine system.
[0010] FIG. 3 is a schematic view of a combined cycle power plant
integrating a steam storage system, according to embodiments of the
disclosure.
[0011] FIG. 4 is a schematic view of a combined cycle power plant
integrating a steam storage system and an extra desuperheater,
according to embodiments of the disclosure.
[0012] FIG. 5 is a schematic view of a combined cycle power plant
integrating a steam storage system and a heat exchanger, according
to embodiments of the disclosure.
[0013] It is noted that the drawings of the disclosure are not to
scale. The drawings are intended to depict only typical aspects of
the disclosure, and therefore should not be considered as limiting
the scope of the disclosure. In the drawings, like numbering
represents like elements between the drawings.
DETAILED DESCRIPTION OF THE INVENTION
[0014] As an initial matter, in order to clearly describe the
current disclosure, it will become necessary to select certain
terminology when referring to and describing relevant machine
components within a steam turbine system. When doing this, if
possible, common industry terminology will be used and employed in
a manner consistent with its accepted meaning. Unless otherwise
stated, such terminology should be given a broad interpretation
consistent with the context of the present application and the
scope of the appended claims. Those of ordinary skill in the art
will appreciate that often a particular component may be referred
to using several different or overlapping terms. What may be
described herein as being a single part may include and be
referenced in another context as consisting of multiple components.
Alternatively, what may be described herein as including multiple
components may be referred to elsewhere as a single part.
[0015] In addition, several descriptive terms may be used regularly
herein, and it should prove helpful to define these terms at the
onset of this section. These terms and their definitions, unless
stated otherwise, are as follows. As used herein, "downstream" and
"upstream" are terms that indicate a direction relative to the flow
of a fluid, such as the working fluid through the turbine engine
or, for example, the flow of air through the combustor or coolant
through one of the turbine's component systems. The term
"downstream" corresponds to the direction of flow of the fluid, and
the term "upstream" refers to the direction opposite to the flow.
The terms "forward" and "aft," without any further specificity,
refer to directions, with "forward" referring to the front or
compressor end of the engine, and "aft" referring to the rearward
or turbine end of the engine. It is often required to describe
parts that are at differing radial positions with regard to a
center axis. The term "radial" refers to movement or position
perpendicular to an axis. In cases such as this, if a first
component resides closer to the axis than a second component, it
will be stated herein that the first component is "radially inward"
or "inboard" of the second component. If, on the other hand, the
first component resides further from the axis than the second
component, it may be stated herein that the first component is
"radially outward" or "outboard" of the second component. The term
"axial" refers to movement or position parallel to an axis.
Finally, the term "circumferential" refers to movement or position
around an axis. It will be appreciated that such terms may be
applied in relation to the center axis of the turbine.
[0016] To extend the operating range of a power plant and increase
its operating flexibility, it is possible to use storage devices
that store thermal energy. One possibility of direct storage is to
store hot water or steam within the water-steam cycle.
[0017] In general, embodiments of the present disclosure integrate
saturated steam storage (sliding pressure storage) into a combined
cycle power plant, and more specifically, into a water-steam cycle.
With such storage, the amount of steam in the water-steam-cycle can
be easily reduced in order to reduce the electrical power output,
and the amount of steam can be increased to increase the electrical
power generation.
[0018] In example embodiments, the steam storage system will be
charged with steam from the cold reheat (CRH), or in other words,
from the steam flow exiting a high pressure steam turbine (HP
turbine), during times when the minimum operating load is reduced
or when a short and quick load drop is required with the intention
to return to the original load soon. Discharging the steam storage
system adds stored steam from the steam storage system to the low
pressure steam flow which is sent to a low pressure steam turbine
(LP turbine). By increasing the mass flow through the LP turbine,
more electricity is generated. Charging at any load leads to a
reduced plant load while discharging at any load results in a plant
load increase higher than the load would be originally. If, for
example, only a GT load increase is desired but not plant load
increase, the steam storage can be charged at any load and the gas
turbine system operates at a slightly higher load point. It is also
possible to operate the gas turbine system at a slightly lower load
point if GT load reduction is desired but no plant load decrease
while the steam storage is discharging.
[0019] In example embodiments, the steam storage system may include
a storage tank. The maximum mass flow to and from the storage tank
is limited by the combined cycle gas turbine design. The storage
capacity is limited by the tank size. After a certain tank size, it
does not make economical and technological sense to build the tank
any bigger. In such a case, additional storage tanks may be added
(not shown for clarity). This enables a customer flexibility to
extend the storage capacity by just adding storage tanks and
connecting them to the existing system. It would be possible to use
a different type of thermal storage, for example one with
phase-changing material to generate steam as well.
[0020] Referring to the drawings, in FIG. 1 a schematic view of
portions of an illustrative prior art combined cycle power
generating system as combined cycle power plant (CCPP) 1 are shown.
Prior art CCPP 1 has gas cycle 2 and water/steam cycle 3. Gas cycle
2 has gas turbine system 4 operatively coupled to generator 5. Gas
turbine system 4 includes compressor 6, combustor 7, and gas
turbine 8 coupled to output shaft 9. In operation, air enters the
inlet of compressor 6, is compressed and then discharged to
combustor 7. A fuel flow 10 is provided to combustor 7 where fuel
such as a gas, e.g., natural gas, or a fluid, e.g., oil, is burned
to provide high energy combustion gases which drive gas turbine 8.
In gas turbine 8, the energy of the hot gases is converted into
work, some of which is used to drive compressor 6 through rotating
shaft 9, with the remainder available for useful work to drive a
load such as generator 5 via shaft 9 for producing electrical
output 11.
[0021] FIG. 1 also represents the combined cycle in its simplest
form in which the energy in exhaust gas 12 exiting gas turbine 8 is
converted into additional useful work. Exhaust gas 12 enters heat
recovery steam generator (HRSG) 13 in which water is converted to
steam in the manner of a boiler.
[0022] Water/steam cycle 3 includes HRSG 13, steam turbine system
14, and generator 15. Steam turbine system 14 includes high
pressure turbine (HP turbine) 16, intermediate pressure steam
turbine (IP turbine) 17, and low pressure turbine (LP turbine) 18.
HRSG 13 has gas duct 19 and heat exchangers 20, 21, 22 that
transfer heat from gas turbine exhaust flow 12 to feed water from
condenser 23 and external water source 24 to generate steam for
powering steam turbine system 14. These heat exchangers heat
incoming water pumped from external water source 24 and/or
recovered from a condenser 23. Heat exchangers 20, 21, 22 may be
mounted in the HRSG duct 19 such that a first stage of water
heating occurs at the downstream end of the HRSG, and progressively
hotter stages occur progressively upstream. Exhaust gas 12 cools as
it flows over heat exchangers 20, 21, 22 and transfers heat to
them, eventually exiting CCPP 1 via exhaust stack 26. Steam at
different temperatures and pressures may be extracted at different
points along the series of heat exchangers 20, 21, 22. Some of this
steam may be routed to steam turbine system 14 driving a generator
15 for electrical output 27. Other portions of this steam may be
routed to heat exchangers upstream in the HRSG 13 for additional
heating to recover as much energy as possible from exhaust gas 12
and provide high pressure steam for the steam turbine system 14 and
other uses. For example, the downstream heat exchanger 22 may
provide low-pressure steam to LP turbine 18, and/or it may provide
low-pressure steam or hot water to another exchanger 21.
[0023] FIG. 2 shows a perspective partial cut-away illustration of
a prior art steam turbine 50. Steam turbine 50 includes a rotor 52
that includes a rotating shaft 54 and a plurality of axially spaced
rotor wheels 56. A plurality of rotating blades 58 are mechanically
coupled to each rotor wheel 56. More specifically, blades 58 are
arranged in rows that extend circumferentially around each rotor
wheel 56. A plurality of stationary vanes 60 extends
circumferentially around shaft 54, and the vanes are axially
positioned between adjacent rows of blades 58. Stationary vanes 60
cooperate with blades 58 to form a stage and to define a portion of
a steam flow path through turbine 50.
[0024] In operation, steam 62 enters an inlet 124 of turbine 50 and
is channeled through stationary vanes 60. Vanes 60 direct steam 62
downstream against blades 58. Steam 62 passes through the remaining
stages imparting a force on blades 58 causing shaft 54 to rotate.
At least one end of turbine 50 may extend axially away from rotor
52 and may be attached to a load or machinery (not shown) such as,
but not limited to, a generator, and/or another turbine.
[0025] As an example, turbine 50 comprises five stages. The five
stages are referred to as L0, L1, L2, L3 and L4. Stage L4 is the
first stage and is the smallest (in a radial direction) of the five
stages. Stage L3 is the second stage and is the next stage in an
axial direction. Stage L2 is the third stage and is shown in the
middle of the five stages. Stage L1 is the fourth and next-to-last
stage. Stage L0 is the last stage and is the largest (in a radial
direction). It is to be understood that five stages are shown as
one example only, and each turbine may have more or less than five
stages.
[0026] Referring now to FIG. 3, a schematic view of CCPP 100
integrating steam storage system 212, according to embodiments of
the disclosure is shown. In an example embodiment, CCPP 100 may
include gas turbine system 102 operably connected to generator 104
as is known in the art, and steam turbine system 200 operably
coupled to generator 104 and/or another generator (not shown).
Steam turbine system 200 may include HP turbine 206, IP turbine
228, and LP turbine 210. In the exemplary embodiment shown, one gas
turbine system 102 is shown with HRSG 202 feeding steam to steam
turbine system 200. However, it should be appreciated that aspects
of the present disclosure can be implemented into power plants with
configurations having multiple gas turbines together with their
HRSG feeding steam to steam turbine system 200, or multiple gas
turbines together with their HRSG feeding steam to multiple steam
turbine systems. Further, in the example embodiment shown in FIG.
3, CCPP 100 is a single shaft system with one generator 104, but
one with skill in the art will readily understand that the
teachings of the disclosure are applicable to any variety of CCPP
configurations. For example, in a multi-shaft arrangement, drive
shaft 106 can be driven by gas turbine 108 of gas turbine system
102 and the steam produced by HRSG 202 drives at least part of
steam turbine system 200 which drives a separate shaft (not shown)
and an additional load such as a second generator (not shown),
which in turn, produces additional electric power. If there is more
than one gas turbine, each gas turbine may drive their own drive
shaft and a respective generator. As such, in some configurations,
turbines 108, 206, 228, and 210 drive common generator 104, but
more than one generator may be provided.
[0027] CCPP 100 has heat exchanger 202 that, in an example
embodiment, may be HRSG 202. In the embodiment shown in FIG. 3,
HRSG 202 may include LP system 203, IP system 205, and HP system
207. LP, IP and HP systems 203, 205 and 207, respectively, of HRSG
202 generally include a drum and a plurality of heat exchangers. In
example embodiments, systems 203, 205 and 207 of HRSG 202 may
include several elements, such as a preheater, a drum, an
evaporator, and a superheater. In operation, steam from HRSG 202
enters an inlet of HP turbine 206, IP turbine 228 and/or LP turbine
210, and is channeled to impart a force on blades thereof (not
shown) causing their common shaft to rotate. As understood, steam
from an upstream turbine may be employed later in a downstream
turbine. The steam thus produced by HRSG 202 drives at least a part
of steam turbine system 200 in which additional work is extracted
to drive shaft 106.
[0028] In an example embodiment, steam turbine system 200 includes
IP turbine 228 fluidly coupled to HP turbine 206 and LP turbine
210. IP turbine 228 is fed from a reheat system of HRSG 202, and
the IP turbine provides an exhaust 232 that feeds into LP turbine
210. Steam 230 is additional steam coming from LP system 203 of
HRSG 202 and is mixed with IP exhaust 232. Steam 230 and exhaust
232 are both sent to LP turbine 210.
[0029] CCPP 100 includes HRSG 202 for generating a steam exhaust
204 feeding into HP turbine 206. In turn, HP turbine 206 provides a
first steam exhaust 208 that fluidly couples HP turbine 206 to an
LP turbine 210. In an example embodiment, first steam exhaust 208
fluidly couples HP turbine 206 to LP turbine 210 via HRSG 202 and
IP turbine 228. A steam storage system 212 is operatively arranged
between HP turbine 206 and LP turbine 210.
[0030] Storage system 212 may include a storage tank or a drum or
any suitable storage unit, or any plurality or combination of such
units. The storage system has a charging mode and a discharging
mode of operation.
[0031] During the charging mode, storage system 212 receives a
portion 214 of first steam exhaust 208 from HP turbine 206 via an
inlet valve 216. Portion 214 is stored within storage system 212 as
a stored steam 218. In an embodiment, the water level in storage
system 212 rises and the pressure increases. The water level and
the pressure increases until stored steam 218 has a pressure that
equals the pressure of first steam exhaust 208. At that point, the
water level and the pressure in steam storage system 212 are at
their highest points and the charging of storage system 212 has
reached its limit. At this storage limit, there is steam and water
inside storage system 212, and as such, the temperature equals the
saturation temperature of the given pressure.
[0032] During the discharging mode, storage system 212 releases a
second steam exhaust 222 via output valve 220. In an example
embodiment, second steam exhaust 222 is saturated steam and output
valve 220 is a pressure-control valve so that saturated steam 222
is released at a constant pressure to LP turbine 210. The water
level and the pressure within steam storage system 212 decreases
during the discharging mode. When extracting steam 222 from storage
system 212, water within storage system 212 evaporates to maintain
the equilibrium within the storage tank, thus leading to a pressure
reduction within the tank. To provide a fixed pressure output from
steam storage system 212, pressure control valve 220 is configured
at the steam outlet in order to maintain a certain pressure
downstream of the valve. In an example embodiment, the steam at the
storage outlet, i.e., control valve 220, is at saturated
conditions.
[0033] Saturated steam exhaust 222 can be superheated by adding
superheated steam downstream from pressure control valve 220. In an
example embodiment, first steam exhaust 208 is used for
superheating because this steam is already available at storage
system 212. However, it should be appreciated that it can be any
steam source with suitable parameters.
[0034] Typically, overheating problems occur when the exit
temperature from HRSG 202 reaches about 600.degree. C., however
this temperature limit depends on material and also on pressure,
and mainly exists only for part load operation. To overcome this
problem, at least one interstage desuperheater may be operatively
arranged between the superheaters (or heat exchangers) of HRSG 202.
For example, interstage desuperheater 234 may be provided between
superheaters A and B of HRSG 202, insterstage desuperheater 236 may
be provided between superheaters B and C of HRSG 202, and/or
interstage desuperheater 235 may be provided between superheaters
A' and B' of HRSG 202. Desuperheating, sometimes called
attemperation or steam conditioning, is the reduction of steam
temperature. Desuperheaters described in this disclosure may
include any now known desuperheaters (e.g., a water injection) or
future developed equivalents.
[0035] Depending on the arrangement of the power plant, additional
desuperheaters, such as, for example, 234, 235 and 236 may be
included for general temperature control. HRSG 202 shown in FIG. 3
is shown with various desuperheaters, but it should be appreciated
that the additional desuperheaters may be optional and can include
any number of desuperheaters based on specifications that the
generating system requires to operate. In an example embodiment,
there are a number of desuperheaters operatively arranged to
maintain the temperature of the steam in steam exhaust 204 going to
HP turbine 206 and the steam exhaust going to IP turbine 228.
[0036] In addition to desuperheater 224 along the live steam flow
between HRSG 202 and HP turbine 206, a desuperheater 226 can be
operatively arranged along the reheat steam flow between HRSG 202
and IP turbine 228.
[0037] FIG. 4 is a schematic of an embodiment of the present
disclosure having a desuperheater 238 configured after inlet valve
216 of storage system 212. In an example embodiment, desuperheater
238 is water injection 238. In an example embodiment, portion 214
of first steam exhaust 208 from HP turbine 206 is mixed with water
from IP system 205 of the HRSG. IP system 205 in general may
include a drum with everything upstream of the IP drum being water,
and downstream of the IP drum being steam. In an embodiment, line
240 is a water connection from IP system 205 to desuperheater 238
in order for desuperheater 238 to reduce the temperature of steam
214. In an example embodiment, water from IP system 205 is used for
desuperheating, however a person having ordinary skill in the art
will appreciate that it can be a water source other than from IP
system 205 with suitable parameters.
[0038] FIG. 5 is a schematic of an embodiment of the present
disclosure having an extra heat exchanger 242 for use when
long-term storage may be desired. When using first steam exhaust
208 to charge storage system 212, first steam exhaust 208 may still
be approximately 150 K superheated. This thermal energy of the
superheated first steam exhaust can be used efficiently by
installing a steam-steam-heat exchanger 242 between first steam
exhaust 208 and LP turbine 210.
[0039] With embodiments of the present disclosure, the storage can
add some percent of additional power (for a discrete period,
depending on the storage size and number of storage tanks) as well
as reduce the minimum load by some percent. The load increase
happens when discharging the storage. During charging, the plant
load is reduced.
[0040] Advantages of the embodiments of the present disclosure
include extending the operating range of combined cycle power
plants, and enable quick reaction to system demands. Integration of
the steam storage into a combined cycle gas turbine plant means
that during charging of the steam storage system, the power plant
will generate less electric power, but thermal power is sent to the
storage system. During discharging of stored steam from within the
storage system, the thermal power is released and the electric
power output increases. Charging at any load leads to a reduced
plant load while discharging at any load results in a plant load
increase higher than the load would be originally.
[0041] Embodiments of the present disclosure enable the power plant
to quickly react to system demands. When delivering system
services, e.g. primary or secondary frequency control, the service
is normally required for a distinct period of time. For a power
plant, this means it has to react quickly, change the load point
and run after a short period, for example 15 minutes, back to the
prior load. The possibility with such storage is that the operation
of the power plant is not so much influenced, but parts of the
service are delivered from the storage. Also, the power plant can
offer a greater range of system services.
[0042] Another advantage of the present disclosure is that the
electrical power output can be changed during charging and
discharging without impacting the operation of the gas turbine. It
also adds a certain surplus on the ramp rate, i.e., the rate that a
generator changes its output. If there is now some additional power
that can be added to the existing ramp rate, a power plant can
offer a higher capacity of such a system serviced. The steam
storage has a faster reaction time than battery storage.
[0043] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the disclosure. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof.
"Optional" or "optionally" means that the subsequently described
event or circumstance may or may not occur, and that the
description includes instances where the event occurs and instances
where it does not.
[0044] Approximating language, as used herein throughout the
specification and claims, may be applied to modify any quantitative
representation that could permissibly vary without resulting in a
change in the basic function to which it is related. Accordingly, a
value modified by a term or terms, such as "about," "approximately"
and "substantially," are not to be limited to the precise value
specified. In at least some instances, the approximating language
may correspond to the precision of an instrument for measuring the
value. Here and throughout the specification and claims, range
limitations may be combined and/or interchanged, such ranges are
identified and include all the sub-ranges contained therein unless
context or language indicates otherwise. "Approximately" as applied
to a particular value of a range applies to both values, and unless
otherwise dependent on the precision of the instrument measuring
the value, may indicate+/-10% of the stated value(s).
[0045] The corresponding structures, materials, acts, and
equivalents of all means or step plus function elements in the
claims below are intended to include any structure, material, or
act for performing the function in combination with other claimed
elements as specifically claimed. The description of the present
disclosure has been presented for purposes of illustration and
description, but is not intended to be exhaustive or limited to the
disclosure in the form disclosed. Many modifications and variations
will be apparent to those of ordinary skill in the art without
departing from the scope and spirit of the disclosure. The
embodiment was chosen and described in order to best explain the
principles of the disclosure and the practical application, and to
enable others of ordinary skill in the art to understand the
disclosure for various embodiments with various modifications as
are suited to the particular use contemplated.
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