U.S. patent application number 15/761550 was filed with the patent office on 2018-11-29 for gas-and-steam combined-cycle power plant.
This patent application is currently assigned to Siemens Aktiengesellschaft. The applicant listed for this patent is Siemens Aktiengesellschaft. Invention is credited to Stefan Becker, Vladimir Danov, Uwe Lenk, Jochen Schafer, Erich Schmid, Alexander Tremel.
Application Number | 20180340451 15/761550 |
Document ID | / |
Family ID | 57113288 |
Filed Date | 2018-11-29 |
United States Patent
Application |
20180340451 |
Kind Code |
A1 |
Becker; Stefan ; et
al. |
November 29, 2018 |
Gas-and-Steam Combined-Cycle Power Plant
Abstract
The present disclosure relates to power plants. Various
embodiments thereof may include a method for operating a
gas-and-steam combined-cycle power plant. For example, some
embodiments may include a method for operating a gas-and-steam
combined-cycle power plant including: providing exhaust gas from a
gas turbine to a steam generator; generating steam by means of the
exhaust gas; driving a generator with the steam via a turbine
installation to provide an electric current; removing the exhaust
gas from the steam generator; and using at least a portion of heat
contained in the exhaust gas downstream from the steam generator to
affect an endothermic chemical reaction.
Inventors: |
Becker; Stefan; (Adelsdorf,
DE) ; Danov; Vladimir; (Erlangen, DE) ; Lenk;
Uwe; (Zwickau, DE) ; Schmid; Erich;
(Nuernberg, DE) ; Schafer; Jochen; (Nuernberg,
DE) ; Tremel; Alexander; (Mohrendorf, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Siemens Aktiengesellschaft |
Muenchen |
|
DE |
|
|
Assignee: |
Siemens Aktiengesellschaft
Muenchen
DE
|
Family ID: |
57113288 |
Appl. No.: |
15/761550 |
Filed: |
September 26, 2016 |
PCT Filed: |
September 26, 2016 |
PCT NO: |
PCT/EP2016/072847 |
371 Date: |
March 20, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
Y02E 20/16 20130101;
F01K 3/188 20130101; F01K 23/105 20130101; F01K 23/10 20130101;
F01K 7/025 20130101; F01K 1/04 20130101; F01K 23/103 20130101; F01K
3/24 20130101; F01K 13/02 20130101; Y02E 20/14 20130101; F01K 3/14
20130101; F01K 3/008 20130101 |
International
Class: |
F01K 23/10 20060101
F01K023/10; F01K 7/02 20060101 F01K007/02; F01K 3/14 20060101
F01K003/14 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 7, 2015 |
DE |
10 2015 219 403.5 |
Claims
1. A method for operating a gas-and-steam combined-cycle power
plant, the method comprising: providing exhaust gas from a gas
turbine to a steam generator; generating steam by means of the
exhaust gas; driving a generator with the steam via a turbine
installation to provide an electric current; removing the exhaust
gas from the steam generator; and using at least a portion of heat
contained in the exhaust gas downstream from the steam generator to
affect an endothermic chemical reaction.
2. The method as claimed in claim 1, wherein the at least a portion
of the heat contained in the exhaust gas downstream from the steam
generator is transferred via a heat exchanger to educts of the
endothermic chemical reaction.
3. The method as claimed in claim 1, further comprising:
branching-off at least some of the steam generated by the steam
generator and storing the at least some of the steam in a steam
accumulator; removing at least a portion of the steam stored in the
steam accumulator from the steam accumulator; heating the at least
a portion of the steam removed from the steam accumulator with heat
released in an exothermic chemical reaction; and routing the heated
steam to the turbine installation to drive the turbine installation
with the heated steam.
4. The method as claimed in claim 3, further comprising using
products of the endothermic chemical reaction as educts of the
exothermic chemical reaction.
5. The method as claimed in claim 3, further comprising supplying
the heated steam to the turbine installation to ramp up the
gas-and-steam combined-cycle power plant from a first load range
into a second load range that is higher than the first load
range.
6. The method as claimed in claim 5, wherein the endothermic
chemical reaction is affected in the second load range.
7. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a U.S. National Stage Application of
International Application No. PCT/EP2016/072847 filed Sep. 26,
2016, which designates the United States of America, and claims
priority to DE Application No. 10 2015 219 403.5 filed Oct. 7,
2015, the contents of which are hereby incorporated by reference in
their entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to power plants. Various
embodiments thereof may include a method for operating a
gas-and-steam combined-cycle power plant.
BACKGROUND
[0003] Gas-and-steam combined-cycle power plants may be known as
COGAS power plants. The gas-and-steam power plant is also referred
to as a combined-cycle power plant, and typically comprises at
least one turbine installation, at least one generator that can be
driven by the turbine installation, for providing electric current,
and at least one gas turbine. When the generator is driven by the
turbine installation, the generator can convert mechanical energy
into electrical energy, or electric current, and provide this
electrical energy, or the electric current. The electric current
can then be fed, for example, into an electricity grid.
[0004] The gas turbine provides exhaust gas, by means of which hot
steam may be generated. For example, a fuel, such as a gaseous fuel
for example, natural gas, is supplied to the gas turbine, the fuel
then burned by means of the gas turbine. In particular, in addition
to the fuel, oxygen or air is supplied to the gas turbine, such
that a fuel-air mixture is produced from the air and the fuel. This
fuel-air mixture is burned, resulting in exhaust gas of the gas
turbine. By means of the exhaust gas, a fluid, e.g. water, is
heated and thereby evaporated, resulting in hot steam. This means
that the hot steam is generated by means of the exhaust gas of the
gas turbine in such a manner that a fluid such as, for example,
water, is evaporated by means of the hot exhaust gas of the gas
turbine.
[0005] The steam is then supplied to the turbine installation, such
that the turbine installation is driven by means of the steam. As
already described, the generator is driven via the turbine
installation, or by means of the turbine installation. The
gas-and-steam combined-cycle power plant is a power plant in which
the principles of a gas-turbine power plant and a steam power plant
are combined. The gas turbine, or its exhaust gas, serves in this
case as a heat source for a downstream steam generator, by means of
which the steam for the turbine installation, for driving the
turbine installation, is generated. The turbine installation is
thus realized as a steam turbine.
[0006] This means that the gas turbine provides its exhaust gas,
which is supplied to the steam generator. Thus, by means of the
exhaust gas supplied to the steam generator, and by means of the
steam generator, hot steam is generated, by means of which the
turbine installation is driven and, via the turbine installation,
the generator is driven, for the purpose of providing electric
current. In addition, the exhaust gas supplied to the steam
generator is removed again, at least in part.
[0007] It has been found that such a gas-and-steam combined-cycle
power plant (COGAS power plant) must be switched off in response to
the electricity demand, such that the generator does not provide an
electric current and, for example, is not driven, and such that no
current is fed into the electricity grid by means of the COGAS
power plant. Owing to the switch-off, the gas-and-steam
combined-cycle power plant can cool down, whereupon a renewed
start-up, or ramping-up, of the gas-and-steam combined-cycle power
plant requires a particularly long time and a particularly high
energy demand.
[0008] For this reason, the gas-and-steam combined-cycle power
plant is usually kept warm during the period in which the
gas-and-steam combined-cycle power plant is switched off. In this
case, the gas-and-steam combined-cycle power plant is kept warm by
means of steam. This steam for retaining warmth is usually
generated by means of a boiler, e.g. a gas boiler. The boiler
evaporates a fluid such as, for example, water. The steam generated
by means of the boiler is routed at least through a part of the
gas-and-steam combined-cycle power plant, to keep the latter warm,
or heat it. The gas-and-steam combined-cycle power plant, after
having been switched off, can then be started in a warm-start
operation, since the gas-and-steam combined-cycle power plant then
already has a sufficiently high temperature at which it can be
started. Nevertheless, as the time during which the gas-and-steam
combined-cycle power plant is switched off increases, an increasing
quantity of steam is required to keep the gas-and-steam
combined-cycle power plant warm, or to heat it, since it cools down
gradually.
SUMMARY
[0009] The teachings of the present disclosure may be embodied in
methods that offer particularly efficient operation. For example, a
method for operating a gas-and-steam combined-cycle power plant
(10) in which exhaust gas is provided by a gas turbine (12) and is
supplied to a steam generator (20), wherein hot steam is generated
by means of the exhaust gas supplied to the steam generator (20)
and by means of the steam generator (20), which steam is used to
drive at least one generator (30), via at least one turbine
installation (22), for the purpose of providing electric current,
and wherein the exhaust gas supplied to the steam generator (20) is
removed from the steam generator (20), may include at least a
portion of heat contained in the exhaust gas downstream from the
steam generator (20) is used to effect an endothermic chemical
reaction.
[0010] In some embodiments, at least the portion of the heat
contained in the exhaust gas downstream from the steam generator
(20) is transferred, via a heat exchanger (38), to educts of the
endothermic chemical reaction.
[0011] Some embodiments include branching-off at least a portion of
the steam generated by means of the steam generator (20) and
storing the branched-off steam in a steam accumulator (34);
removing at least a portion of the steam, stored in the steam
accumulator (34), from the steam accumulator (34); heating the
steam removed from the steam accumulator (34) by means of heat that
is released in an exothermic chemical reaction; and routing the
heated steam to the turbine installation (22), which is driven by
means of the supplied heated steam.
[0012] In some embodiments, products of the endothermic chemical
reaction are used as educts of the exothermic chemical
reaction.
[0013] In some embodiments, the heated steam for driving the
turbine installation (22) is supplied to the turbine installation
(22), in order to ramp up the gas-and-steam combined-cycle power
plant (10) from a first load range into a second load range that is
higher than the first load range.
[0014] In some embodiments, the endothermic chemical reaction is
effected in the second load range.
[0015] Some embodiments may include a gas-and-steam combined-cycle
power plant (10) that executes a method as described above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Further advantages, features, and details are disclosed by
the following description of an exemplary embodiment and with
reference to the drawing. The features and feature combinations
mentioned in the description and the features and feature
combinations mentioned in the following description of the FIGURE
and/or shown alone in the single FIGURE can applied, not only in
the respectively specified combination, but also in other
combinations or singly, without departure from the scope of the
invention.
[0017] The drawing, in the single FIGURE, shows a schematic
representation of a gas-and-steam combined-cycle power plant, in
which a thermochemical heat accumulator is used to realize a
particularly high efficiency according to the teachings of the
present disclosure.
DETAILED DESCRIPTION
[0018] Particularly efficient operation can be realized in
embodiments wherein at least a portion of heat contained in the
exhaust gas of the gas turbine downstream from the steam generator
is used to effect an endothermic chemical reaction, i.e. a reaction
that absorbs chemical heat. This means that the exhaust gas, for
example flowing out of the steam generator--in the direction of
flow of the exhaust gas of the gas turbine--has a temperature
downstream from the steam generator, such that, in the exhaust gas
of the gas turbine downstream from the steam generator, i.e. after
generation of the steam, there is heat contained in the exhaust gas
of the gas turbine. This heat that is contained in the exhaust gas
downstream from the steam generator, or after the steam generator,
is used to affect the endothermic chemical reaction. For this
purpose, the heat contained in the exhaust gas is supplied to the
endothermic chemical reaction, or to educts of the endothermic
chemical reaction.
[0019] As a result, at least a portion of the heat supplied to the
endothermic chemical reaction is stored in products of the
endothermic chemical reaction, such that a thermochemical
accumulator, in particular a thermochemical heat accumulator, can
be created. The heat contained in the exhaust gas of the gas
turbine downstream from the steam generator can be stored, at least
partly, in the products of the endothermic chemical reaction,
wherein the heat stored in the products can be used, for example,
at a subsequent point in time and/or for other purposes. Some
embodiments use heat contained in the exhaust gas of the gas
turbine after the steam generator, which is usually lost without
being used, for the purpose of storing at least a portion of the
heat contained in the exhaust gas downstream from the steam
generator.
[0020] In particular, the heat may be stored for district heating
purposes. For example, an exothermic chemical reaction, i.e. a
reaction giving off chemical heat, can be affected, wherein the
products of the endothermic chemical reaction are educts of the
exothermic chemical reaction, or are used as educts of the
exothermic reaction. In the course of the exothermic chemical
reaction, heat is released, by means of which a medium, in
particular water, can be heated efficiently. Products of the
exothermic chemical reaction may be used, for example, as the
educts of the endothermic reaction.
[0021] The thermochemical heat accumulator can be used to realize
particularly high flexibility in respect of the realization of
district heating. In particular, it is possible to store heat, or
energy, in the thermochemical heat accumulator, such that, in
particular in the case of high demands for heat, a medium, in
particular water, can be heated effectively by means of the heat
stored in the thermochemical heat accumulator. Since energy
contained in the exhaust gas downstream from the steam generator is
used for this purpose, a particularly high efficiency can be
realized. The heat that is stored in the products of the
endothermic reaction, and released in the exothermic reaction, is
transferred, for example, to heat the medium. The medium can then
be used for heating purposes, in particular to realize district
heating.
[0022] In some embodiments, at least a portion of the heat
contained in the exhaust gas downstream from the steam generator is
transferred, via a heat exchanger, to educts of the endothermic
chemical reaction.
[0023] In some embodiments, at least a portion of the steam
generated by means of the steam generator is branched-off and
stored in a steam accumulator. In addition, at least a portion of
the steam stored in the steam accumulator is removed from the steam
accumulator. The steam removed from the steam accumulator is heated
by means of heat that is released in the exothermic chemical
reaction. In addition, the heated steam is routed to the turbine
installation, which is driven, in particular accelerated, by means
of the supplied heated steam.
[0024] In some embodiments, products of the endothermic chemical
reaction are used as educts of the exothermic chemical
reaction.
[0025] In some embodiments, the heated steam for driving the
turbine installation is supplied to the turbine installation, to
ramp up the gas-and-steam combined-cycle power plant from a first
load range into a second load range that is higher than the first
load range. In some embodiments, the endothermic chemical reaction
is affected in the second load range.
[0026] Some embodiments may include a gas-and-steam combined-cycle
power plant executing a method a described above. Advantageous
designs of the method are to be regarded as advantageous designs of
the gas-and-steam combined-cycle power plant, and vice versa.
[0027] The single FIGURE, in a schematic representation, shows a
gas-and-steam combined-cycle power plant 10, also referred to as a
COGAS power plant or--to improve readability--as a power plant. The
power plant 10 comprises at least one gas turbine 12, to which fuel
is supplied, for example in the course of a process for operating
the power plant 10. This supply of fuel to the gas turbine 12 is
indicated in the FIGURE by a direction arrow 14. The fuel may
include a gaseous fuel such as, for example, natural gas. In
addition, air is supplied to the gas turbine 12, this being
indicated in the FIGURE by a direction arrow 16. The fuel is burned
by means of the gas turbine 12, resulting in exhaust gas of the gas
turbine 12. The gas turbine 12 thus provides the exhaust gas, as
indicated in the FIGURE by a direction arrow 18. A mixture of the
fuel and the air, for example, is formed in the gas turbine 12,
this mixture being burned. This results in the exhaust gas of the
gas turbine 12.
[0028] It can be seen from the direction arrow 18 that the exhaust
gas is supplied to a steam generator 20 of the power plant 10. The
steam generator 20 may be referred to as a boiler or evaporator. In
addition, a fluid, e.g. water, is supplied to the steam generator
20. A transfer of heat is affected from the exhaust gas of the gas
turbine 12 to the water, as a result of which the water is heated
and evaporated. As a result, steam is generated from the water.
This means that, by means of the exhaust gas of the gas turbine 12
and by means of the steam generator 20, steam is generated from the
water (fluid) supplied to the steam generator 20. As a result of
this transfer of heat from the exhaust gas to the water, the
exhaust gas is cooled, such that it is removed from the steam
generator 20, for example, at a first temperature T1. The first
temperature T1 is, for example, at least substantially 90.degree.
C. (degrees Celsius).
[0029] The power plant 10 additionally comprises a turbine
installation 22, which in the present case comprises a first
turbine 24 and a second turbine 26. The turbine 24 may comprise a
high-pressure turbine and turbine 26 may comprise a medium-pressure
and low-pressure turbine. The steam generated by means of the
exhaust gas of the gas turbine 12 and by means of the steam
generator 20 is supplied to the turbine installation 22, such that
the turbine installation 22, in particular the turbines 24 and 26,
are driven by means of the generated hot steam. By means of the
turbine installation 22, energy contained in the hot steam is
converted to mechanical energy, the mechanical energy being
provided via a shaft 28. The turbine installation 22 comprises, for
example, turbine wheels, not represented in detail in the FIGURE,
to which the steam is supplied. As a result, the turbine wheels are
driven by means of the steam. The turbine wheels are connected, for
example, in a rotationally fixed manner to the shaft 28, such that
the shaft 28 is driven by the turbine wheels when the turbine
wheels are driven by means of the steam.
[0030] The power plant 10 additionally comprises at least one
generator 30, which can be driven, or is driven, by the turbine
installation 22, via the shaft 28. The mechanical energy provided
via the shaft 28 is thus supplied to the generator 30, at least a
portion of the supplied mechanical energy being converted to
electrical energy, or electric current, by means of the generator
30. The generator 30 can provide this electric current, which, for
example, can be fed into an electricity grid.
[0031] The steam is removed from the turbine installation 22 and
supplied to a heat exchanger 32, which may comprise a condenser. By
means of the heat exchanger 32, the steam is cooled, as a result of
which the steam condenses. As a result of this, the steam again
becomes the aforementioned water, which can be supplied back to the
steam generator 20. To cool the steam by means of the heat
exchanger 32, a cooling medium, in particular a cooling fluid, may
be supplied to the heat exchanger 32. A transfer of heat can then
be affected from the steam to the cooling fluid, as a result of
which the steam is cooled and subsequently condenses.
[0032] The power plant 10 has a plurality of lines, not represented
in greater detail in the FIGURE, flowing through which there are
respective flows of the steam generated by means of the exhaust gas
of the gas turbine 12. These flows may have differing temperatures.
Represented in the FIGURE are differing temperatures T2, T3, and T4
of the steam generated by means of the exhaust gas of the gas
turbine 12, for example the temperature T2 being 595.degree. C.,
the temperature T3 360.degree. C., and the temperature T4
240.degree. C. The water leaves the condenser, for example, at a
temperature T5, which is, for example, 40.degree. C.
[0033] Depending on the demand for electricity, the power plant 10
is activated, i.e. switched on, and/or deactivated, i.e. switched
off. For example, the power plant 10 is switched off if there is
only low demand for electricity. If the demand for electricity
increases, then the power plant 10, after having been switched off,
is switched on again. This switching-on subsequent to switching-off
may be a warm start, to enable the power plant 10 to be switched on
in a rapid and energy-efficient manner. To realize this warm start,
in particular to realize a particularly energy-efficient warm
start, the power plant 10, after having been switched off and
during a period in which the power plant is switched off, is kept
warm, or heated, in order to avoid excessive cooling off, or
cooling down, of the power plant 10.
[0034] The gas turbine 12 provides its exhaust gas to the steam
generator 20. In addition, the water is supplied to the steam
generator 20. By means of the exhaust gas of the gas turbine 12
supplied to the steam generator, and by means of the steam
generator 20, the water is heated and evaporated, at least partly,
as a result of which steam is generated. In addition, the exhaust
gas of the gas turbine 12 that is supplied to the steam generator
20 is removed, at least partly, from the steam generator 20.
[0035] To realize a particularly high efficiency, or particularly
efficient operation, the power plant 10 may comprise a
thermochemical heat accumulator 34 comprising at least one reactor.
Since the exhaust gas of the gas turbine 12--relative to a
direction of flow of the exhaust gas of the gas turbine
12--downstream from the steam generator 20, i.e. after the steam
generator 20, has the temperature T1, the exhaust gas of the gas
turbine 12 downstream from the steam generator 20 contains
heat.
[0036] At least a portion of this heat contained in the exhaust gas
of the gas turbine 12 downstream from the steam generator 20--as
indicated in the FIGURE by a direction arrow 36--is supplied to the
thermochemical heat accumulator 34 (reactor). This heat supplied to
the thermochemical heat accumulator 34 is used to affect an
endothermic chemical reaction. In other words, an endothermic
chemical reaction is affected by means of the heat, from the
exhaust gas removed from the steam generator 20, that is supplied
to the thermochemical heat accumulator 34. As a result, the heat
supplied to the thermochemical heat accumulator 34, or at least a
portion of the heat supplied to the thermochemical heat accumulator
34, is stored in products of the endothermic chemical reaction, the
stored heat being able to be used according to demand.
[0037] At least the portion of the heat contained in the exhaust
gas of the gas turbine 12 downstream from the steam generator 20 is
supplied to the thermochemical heat accumulator 34, in particular
to the endothermic chemical reaction, or educts of the endothermic
chemical reaction, for example via at least one heat exchanger 38,
through which at least a portion of the exhaust gas flows. In this
case, there is a transfer of heat from the exhaust gas, via the
heat exchanger 38, to educts of the endothermic chemical reaction.
Relative to the direction of flow of the exhaust gas, the heat
exchanger 38 is arranged downstream from the steam generator
20.
[0038] As a result of the described transfer of heat, the exhaust
gas is cooled. The exhaust gas that is supplied to the heat
exchanger 38--as indicated in the FIGURE by a direction arrow
40--is, for example, removed from the heat exchanger 38, and
downstream from the heat exchanger 38 has, for example, a
temperature T6 that is 70.degree. C. and less than the temperature
T1. In addition, the exhaust gas may have a mass flow rate of 884
kg/s and a pressure of one bar. Furthermore, at least a portion of
the exhaust gas flowing out of the steam generator 20 is supplied
to the heat exchanger 38, or to the thermochemical heat accumulator
34.
[0039] The endothermic chemical reaction is, for example, a forward
reaction of a chemical equilibrium reaction. In the course of the
forward reaction, products of the endothermic chemical reaction are
produced from the educts of the endothermic chemical reaction
(forward reaction). This chemical equilibrium reaction also
comprises a back reaction, realized as an exothermic chemical
reaction. In this case the products of the forward reaction are
educts of the back reaction, and products of the back reaction are
the educts of the forward reaction. The forward reaction and/or the
back reaction is/are affected, for example, in the reactor, i.e. in
the thermochemical heat accumulator 34.
[0040] Heat is released in the course of the back reaction. This
heat that becomes free or is released in the course of the back
reaction can be used for heating purposes, in particular for
district heating purposes. For example, it is conceivable to use
heat released in the course of the back reaction to generate steam,
and/or to heat, in particular to superheat, provided steam, in
order to heat, for example, at least a portion of the power plant
by means of the generated, or heated, steam, or alternatively to
drive, in particular to accelerate, the turbine installation 22,
such that, for example, the power plant can be ramped-up from a
first load range into a second load range that is higher than the
first.
[0041] In the present case, however, the heat released in the back
reaction is used for heating purposes, in particular district
heating purposes. In some embodiments, a fluid may be heated by
means of the heat released in the back reaction. The water is
supplied to a further heat exchanger 42 of the thermochemical heat
accumulator, as indicated in the FIGURE by a direction arrow 44.
The heat released in the back reaction is supplied, via the heat
exchanger 42, to the water flowing through the heat exchanger 42,
as a result of which the water is heated. The heated water is
removed from the heat exchanger 42, as indicated in the FIGURE by a
direction arrow 46. The water has, for example, a mass flow rate of
1100 kg/s (kilograms per second). The water is provided at a
temperature T7, for example, the water being supplied at the
temperature T7 to the heat exchanger 42. By means of the heat
exchanger 42, the water is heated to a temperature T8, for example
the temperature T7 being 65.degree. C. (degrees Celsius) and the
temperature T8 being 100.degree. C. The temperature T8 is thus
greater than the temperature T7, the water having the temperature
T7 upstream from the heat exchanger 42, and the temperature T8
downstream from the heat exchanger 42. It is additionally provided,
for example, that the water has a pressure of 14.5 bar, the water
being provided at this pressure and at the temperature T7, and
supplied to the heat exchanger 42.
[0042] Since the forward reaction is affected with the exhaust gas
at 90.degree. C., the thermochemical heat accumulator is charged at
90.degree. C. Since the water is heated, by means of the
thermochemical heat accumulator 34, to 130.degree. C., the
thermochemical heat accumulator 34 is discharged at 130.degree.
C.
[0043] The use of the heat exchanger 38 makes it possible to
realize a spatial separation of the educts of the forward reaction
from the exhaust gas, such that the exhaust gas does not come into
direct contact with the educts of the forward reaction.
Alternatively, it is conceivable that the exhaust gas does come
into direct contact with the educts of the forward reaction, and in
this case flows onto, or around, the educts. The heat exchanger 38,
for example, is then omitted. This is also transferrable to the
back reaction: the use of the heat exchanger 42 makes it possible
to realize a spatial separation of the educts and/or products of
the back reaction from the water that is heated by means of the
released heat, such that the water does not come into direct
contact with the educts and/or products of the back reaction.
Alternatively, it is conceivable that the water does come into
direct contact with the educts and/or products of the back
reaction, and in this case flows onto, or around, the educts and/or
products. The heat exchanger 42, for example, is then omitted.
[0044] The water heated by means of the thermochemical heat
accumulator 34 can be used, for example, to supply households with
hot water, and/or for household heating. As a result, a
particularly efficient process overall can be realized. In
addition, it is possible to realize particularly high flexibility
of the heat supply. In particular, it is conceivable for peak
loads, or high demands for heat, to be covered in an
energy-efficient manner by means of the thermochemical heat
accumulator 34, since at least a portion of the energy contained in
the exhaust gas downstream from the steam generator 20 is used, at
least indirectly, to heat the water. Depending on the mass flow
rate of the exhaust gas and of the water, it is conceivable to
supply only a portion of the exhaust gas downstream from the steam
generator 20 to the heat exchanger 38, and/or only a portion of the
water to the heat exchanger 42, to ensure, in particular, an at
least substantially continuous heating of the water by means of the
thermochemical heat accumulator 34.
* * * * *