U.S. patent application number 14/777253 was filed with the patent office on 2016-01-14 for power generation system and method to operate.
This patent application is currently assigned to SIEMENS AKTIENGESELLSCHAFT. The applicant listed for this patent is SIEMENS AKTIENGESELLSCHAFT. Invention is credited to Anders Stuxberg.
Application Number | 20160010511 14/777253 |
Document ID | / |
Family ID | 47913187 |
Filed Date | 2016-01-14 |
United States Patent
Application |
20160010511 |
Kind Code |
A1 |
Stuxberg; Anders |
January 14, 2016 |
POWER GENERATION SYSTEM AND METHOD TO OPERATE
Abstract
A power generation system includes an oxy-fuel-burner, a steam
cycle, and a recirculation line for feeding a part of working media
of the steam cycle into the oxy-fuel-burner. A system and a method
provides at least one first feed-water-preheater and wherein the
steam cycle joins into the recirculation line downstream the at
least one first feed water pre-heater and extracting a tenth
working-media-stream from the steam cycle, extracting an eighth
working-media-stream as carbon-dioxide downstream the first
condenser, wherein the at least one first feed water-preheater is
heated with a working media stream extracted from the first steam
turbine, namely a fifth working-media-stream.
Inventors: |
Stuxberg; Anders; (Finspong,
SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SIEMENS AKTIENGESELLSCHAFT |
Munich |
|
DE |
|
|
Assignee: |
SIEMENS AKTIENGESELLSCHAFT
Munich
DE
|
Family ID: |
47913187 |
Appl. No.: |
14/777253 |
Filed: |
March 21, 2014 |
PCT Filed: |
March 21, 2014 |
PCT NO: |
PCT/EP2014/055725 |
371 Date: |
September 15, 2015 |
Current U.S.
Class: |
60/775 ;
60/39.12 |
Current CPC
Class: |
Y02E 20/344 20130101;
Y02E 20/32 20130101; F01K 7/22 20130101; Y02E 20/326 20130101; F01K
25/005 20130101; F01K 7/38 20130101; Y02E 20/34 20130101 |
International
Class: |
F01K 25/00 20060101
F01K025/00; F01K 7/38 20060101 F01K007/38 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 21, 2013 |
EP |
13160404.3 |
Claims
1. A power generation system (PGS) comprising an oxy-fuel-burner
(OXB), wherein said oxy-fuel-burner (OXB) is made to generate a
first burner-discharge-fluid from burning fuel (F) with an oxygen
containing gas (O2), said oxygen containing gas (O2) having oxygen
content which is higher than the oxygen content of ambient air, a
recirculation line (RCL) for feeding a first liquid into said
oxy-fuel-burner (OXB) to mix with said generated first
burner-discharge-fluid to a first working-media-stream (EXH1), a
steam cycle (RC) operated with said first working-media-stream
(EXH1), wherein said steam cycle (RC) comprises at least one first
steam turbine (ST1) expanding at least a part of said first
working-media-stream (EXH1), namely a third working-media-stream
(EXH3), wherein said first steam turbine (ST1) has at least one
output port for expanded fluid, one of which providing a seventh
working-media-stream (EXH7), wherein said steam cycle (RC)
comprises at least one first water separator (CON1), downstream
said first steam turbine (ST1) condensing part of said seventh
working-media-stream (EXH7), wherein said first water separator
(CON1) has at least one output port for condensed fluid, one of
which providing a ninth working-media-stream (EXH9), wherein said
steam cycle (RC) comprises at least one first feed-water-pump
(FWP1) downstream of said first water separator (CON1) delivering
said ninth working-media-stream (EXH9) to a higher pressure level,
with an output of a feed-water-pump-output-stream, wherein said
steam cycle (RC) comprises at least one first feed-water pre-heater
(WPH1) downstream said first feed-water-pump (FWP1) heating at
least a part of said feed-water-pump-output-stream, namely a
thirteenth working-media-stream (EXH13), wherein said steam cycle
(RC) leads into said recirculation line (RCL) downstream said at
least one first feed water pre-heater (WPH1) feeding said
thirteenth working-media-stream (EXH13) into said recirculation
line (RCL) as said first liquid, wherein a part of working media in
said steam cycle (RC) is extracted from said steam cycle (RC), as a
tenth extraction-fluid-stream (EXH10), said first water separator
(CON1) further extracts carbon-dioxide from said seventh
working-media-stream (EXH7) via a further output port of said first
water separator (CON1) as an eighth carbon-dioxide-stream (EXH8),
wherein one of said output ports of said first steam turbine (ST1)
provides a fifth working-media-stream (EXH5) and wherein said at
least one first feed water-pre-heater (WPH1) is heated via said
fifth working-media-stream (EXH5).
2. The power generation system (PGS) according to claim 1, further
comprising a second steam turbine (ST2) downstream of said
oxy-fuel-burner (OXB) and upstream of said first steam turbine
(ST1) receiving said first working-media-stream (EXH1) from said
oxy-fuel-burner (OXB).
3. The power generation system (PGS) according to claim 2, further
comprising a first heat exchanger (HEX1), downstream said
oxy-fuel-burner (OXB) and upstream said second steam turbine (ST2)
wherein at least a part of said first working-media-stream (EXH1)
exiting said second steam turbine (ST2), comprising a third
working-media-stream (EXH3) is heated up by said first heat
exchanger (HEX1) receiving thermal energy from said first
working-media-stream (EXH1).
4. The power generation system (PGS) according to claim 1, wherein
said recirculation line (RCL) comprises at least one adjustable
valve (WSV) to control the flow through said recirculation line
(RCL).
5. The power generation system (PGS) according to claim 1, wherein
said at least one first feed water-pre-heater (WPH1) comprises a
degasification part to collect gaseous working media from the
condensing of the provided said fifth working-media-stream
(EXH5).
6. The power generation system (PGS) according to claim 1, further
comprising upstream said oxy-fuel-burner (OXB), an air separation
unit (ASU) as part of said power generation system (PGS) to provide
pure oxygen from ambient air.
7. A method to operate a power generation system (PGS) comprising:
generating a first burner-discharge-fluid from burning an oxygen
containing gas (O2) and fuel (F), wherein an oxygen content of said
oxygen containing gas (O2) is higher than the oxygen content of
ambient air, providing a steam cycle (RC) comprising at least one
first steam turbine (ST1), at least one first water separator
(CON1), downstream said first steam turbine (ST1), at least one
first feed-water-pump (FWP1) downstream said first water separator
(CON1), at least one first feed-water-preheater (WPH1) downstream
said first feed-water-pump (FWP1), extracting a part of working
media from said steam cycle (RC) by a recirculation line (RCL) and
feeding a first liquid, as said part of said working media into
said oxy-fuel-burner (OXB) to mix with said generated first
burner-discharge-fluid to result in a first working-media-stream
(EXH1), operating said steam cycle (RC) with said first
working-media-stream (EXH1), expanding at least a part of said
first working-media-stream (EXH1), comprising a third
working-media-stream (EXH3) by said at least one first steam
turbine (ST1), outputting a seventh working-media-stream (EXH7)
from at least one output port for an expanded fluid of said first
steam turbine (ST1), the expanded fluid being a part of said third
working-media-stream (EXH3), condensing a part of said seventh
working-media-stream (EXH7) by said at least one first water
separator (CON1), delivering at least a part of said seventh
working-media-stream (EXH7) downstream of said first water
separator (CON1) to a higher pressure level, comprising a ninth
working-media-stream (EXH9), by said at least one first
feed-water-pump (FWP1), and outputting a
feed-water-pump-output-stream by said at least one first
feed-water-pump (FWP1), heating at least a part of said
feed-water-pump-output-stream, comprising a thirteenth
working-media-stream (EXH13) by at least one first
feed-water-preheater (WPH1), feeding at least a part of said
thirteenth working-media-stream (EXH13) from said steam cycle (RC)
as said first liquid into said recirculation line (RCL) downstream
said at least one first feed water pre-heater (WPH1), extracting a
part of working media of said steam cycle (RC) from said steam
cycle (RC), as a tenth extraction-fluid-stream (EXH10), extracting
a part of said seventh exhaust-fluid-stream (EXH7) as
carbon-dioxide downstream said first water separator (CON1),
comprising an eighth carbon-dioxide-stream (EXH8), heating said at
least one first feed water-preheater (WPH1) by an output-stream
extracted from said first steam turbine (ST1), comprising a fifth
working-media-stream (EXH5).
8. The method according to claim 7 further comprising expanding
received said first working-media-stream (EXH1) from said
oxy-fuel-burner (OXB) by a second steam turbine (ST2) downstream of
said oxy-fuel-burner (OXB) and upstream of said first steam turbine
(ST1).
9. The method according to claim 7 further comprising heating up at
least a part of said first working-media-stream (EXH1) exiting said
second steam turbine (ST2), comprising a third working-media-stream
(EXH3) by a first heat exchanger (HEX1) receiving thermal energy
from said first working-media-stream (EXH1), said first heat
exchanger (HEX1) being provided downstream said oxy-fuel-burner
(OXB) and upstream said second steam turbine (ST2).
10. The method according to claim 7 further comprising controlling
the flow through said recirculation line (RCL) by at least one
adjustable valve (WSV) or pump or compressor.
11. The method according to claim 7 further comprising, degasifying
to collect gaseous working media from the condensing of the
provided said fifth working-media-stream (EXH5).
12. The method according to claim 7 further comprising, providing
an air separation unit (ASU) as part of said power generation
system (PGS) to provide pure oxygen from ambient air upstream said
oxy-fuel-burner (OXB).
13. The power generation system (PGS) according to claim 1, wherein
the first liquid comprises water.
14. The power generation system (PGS) according to claim 1, wherein
the at least one first water separator (CON1) comprises a
condenser.
15. The power generation system (PGS) according to claim 1, wherein
the part of working media in said steam cycle (RC) is extracted
from said steam cycle (RC) downstream said first feed-water-pump
(FWP1).
16. The power generation system (PGS) according to claim 1, wherein
said tenth extraction-fluid-stream (EXH10) comprises water.
17. The method according to claim 7, wherein the first liquid
comprises water.
18. The method according to claim 7, wherein the at least one first
water separator (CON1) comprises a condenser.
19. The method according to claim 7, wherein extracting the part of
working media of said steam cycle (RC) from said steam cycle (RC)
is downstream said first feed-water-pump (FWP1).
20. The method according to claim 7, wherein said tenth
extraction-fluid-stream (EXH10) comprises water.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is the US National Stage of International
Application No. PCT/EP2014/055725 filed Mar. 21, 2014, and claims
the benefit thereof. The International application claims the
benefit of European Application No. EP13160404 filed Mar. 21, 2013.
All of the applications are incorporated by reference herein in
their entirety.
FIELD OF INVENTION
[0002] The invention relates to a power generation system
comprising an oxy-fuel-burner and a steam cycle.
BACKGROUND OF INVENTION
[0003] Power generation systems and respective methods to operate
such systems are known for a long time since mechanical power or
electrical power is generated especially by burning a fuel with an
oxygen containing gas. Recently concerns came up about
carbon-dioxide content in air increasing up to an amount where a so
called green-house effect might occur. Since such awareness is
rising several projects are initiated to reduce the emission of
carbon-dioxide. One of those projects is burning a fuel with an
oxygen containing gas other than air to a avoid the generation of
NOx (nitrogen oxides) and to avoid the mixing of essential inert
components with the carbon-dioxide generated during combustion to
more easily enable the separation of carbon-dioxide from the
exhaust gas generated. This easy separation simplifies storage of
pure carbon-dioxide in a final storage capacity. Essentially pure
carbon-dioxide can further better be used for subsequent chemical
processes. The oxygen containing gas is basically pure oxygen with
minor impurities generated by for example an air separation unit,
which can be of conventional membrane type. In the context of this
invention an oxy-fuel-burner is characterized by burning basically
a fuel with an oxygen containing gas wherein said oxygen containing
gas has significant higher oxygen content than ambient air or
wherein oxygen is its main component or wherein said oxygen
containing gas is preferably pure oxygen with some impurities. This
oxygen containing gas may contain some further additives but its
main component is preferably oxygen.
[0004] One known power generation system is disclosed in U.S. Pat.
No. 7,021,063 B2, which deals with an oxy-fuel-burner respectively
gas generator comprising a recuperative heat exchanger for
reheating of steam that has passed a first expansion machine stage,
which heat exchanger is heated by outlet steam respectively exhaust
from said gas generator.
[0005] The total efficiency of a conventional power generation
system with an oxy-fuel-burner is significantly below the
efficiency of an ordinary power generation system if the energy
consumption of the air separation unit is considered. The
efficiency is therefore to be improved to make this technology
economically feasible and to have a positive effect on the
environment.
SUMMARY OF INVENTION
[0006] It is an object of the invention to improve the efficiency
of the known power generation system comprising an
oxy-fuel-burner.
[0007] This object of enhancing the efficiency of the incipiently
defined power generation system is achieved by a power generation
system according to the claims. Further this object is achieved by
a method according to the claims.
[0008] One aspect of the proposed improvement of the power
generation system respectively the method according to the
invention is the addition of heat exchangers for preheating of the
re-circulated feed water submitted to the oxy-fuel-burner for
mixing into exhaust stream of the oxy-fuel-burner (being a working
media for a steam cycle). According to the invention by preheating
with extraction steam the cycle performance is improved.
[0009] In the cycle according to the invention the steam
respectively working media (substantially exhaust-fluid of the
oxy-fuel-burner) taken from the steam turbine(s) contains
carbon-dioxide in a substantial concentration, typically more than
5%, in particular about 10% by volume, which makes the cycle much
different from a conventional steam cycle. The carbon-dioxide led
to the pre-heaters is advantageously separated from the pre-heaters
and then collected to be routed to an export carbon-dioxide stream.
In particular a carbon-dioxide compression process for the delivery
to a final user--for example enhanced oil recovery or methane
synthesis--is integrated in the power generation system
respectively method.
[0010] A further beneficial improvement of the process according to
the invention is obtained by providing a recuperator respectively
first heat exchanger downstream said oxy-fuel-burner before the
exhaust-fluid of the oxy-fuel-burner (a first working-media-stream)
enters a steam turbine. This heat exchanger respectively
recuperator re-heats steam respectively the first
working-media-stream that has passed a first expansion through said
steam turbine, wherein the exhaust-fluid from said oxy-fuel-burner
is heating a working-media-stream from said steam turbine. This
heat exchanger provides a certain protection for the downstream
steam turbine as it provides some heat capacity damping thermal
gradients from upstream equipment control variations or
disturbances. Further this heat exchanger assist in protecting the
turbine from possible water droplets carried over from said
oxy-fuel-burner.
[0011] Said oxy-fuel-burner according to the invention is basically
a gas generator generating an exhaust gas respectively exhaust
fluid from a fuel burned or combusted with essentially pure oxygen.
This exhaust gas is referred to as exhaust-fluid since it might
contain liquid components or parts of the fluid might condense to a
liquid. As this exhaust-fluid is a burned fluid (thus exhaust in
this respect) of the oxy-fuel-burner but also a medium for the
steam cycle, it is also called working-media-stream in this
document. All modifications and processing of this working-media
stream within the steam cycle will also be called working-media
stream.
[0012] Another beneficial improvement of the invention is given by
providing at least one adjustable valve to control the flow through
said recirculation line. This control feature allows maintaining
the desired exhaust-fluid temperature downstream said
oxy-fuel-burner (thus also called burner-discharge-fluid)
respectively before said exhaust-fluid or working-media-stream
enters any turbine equipment. Advantageously a control unit
controls the position of said adjustable valve in the recirculation
line according to a temperature measurement upstream a turbine
(i.e. steam turbine) of the power generation system. This control
unit is designed such that it receives the measurement results from
temperature measurement and submits control signals to said control
valve. The control method in particular is designed such that the
valve opens further when exceeding a temperature limit is
recognized. Further the valve control unit can be designed such
that upper limits of temperature increases respectively steep
temperature transients in a turbine of the power generation system
are avoided.
[0013] Another embodiment provides a degasification port at said at
least one feed water pre-heater to collect gaseous carbon-dioxide
from the condensing exhaust-fluid.
[0014] Another embodiment of the invention provides an air
separation unit upstream of said oxy-fuel-burner to advantageously
separate oxygen from ambient air to be burned with a fuel in said
oxy-fuel-burner. This air separation unit can be of a membrane
type.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The above mentioned attributes and other features and
advantageous of this invention and the manner of attaining them
will become more apparent and the invention itself will be
understood by reference to the following description of the
currently known best mode of carrying out the invention taken in
conjunction with the accompanying drawings, wherein
[0016] FIG. 1 shows a schematic flow diagram of an oxy fuel power
plant comprising the arrangement according to the invention and
depicting the method according to the invention.
DETAILED DESCRIPTION OF INVENTION
[0017] FIG. 1 is a schematic depiction of a simplified flow diagram
showing a power generation system and illustrating a method
according to the invention. Fuel F and oxygen O.sub.2 from an air
separation unit ASU are both elevated to a higher pressure level by
compressors C1, C2, C3, C4, C5 which compressors C1, C2, C3, C4, C5
are respectively provided with intercoolers INT1, INT2, INT3 before
both fluids are injected in an oxy-fuel-burner OXB at a pressure of
for example 150 bar. In said oxy-fuel-burner OXB--which can also be
considered as a gas generator--combustion takes place of said fuel
F with said oxygen O.sub.2 generating exhaust gas hereinafter
referred to as exhaust-fluid or first burner-discharge-fluid. This
exhaust-fluid will be modified as explained in the paragraph below
and converted to a first working-media-stream EXH1--and exits said
oxy-fuel-burner OXB and enters a first heat exchanger HEX1 (wherein
the first working-media-stream EXH1 heats a second medium).
[0018] The temperature of said first working-media-stream EXH1 is
adjusted by controlling a flow of evaporating media--particularly
water as medium--as recirculating stream to the oxy-fuel-burner OXB
to be boiled off and thus cool the first burner-discharge-fluid to
the right temperature (resulting in the first working-media-stream
EXH1 then) to subsequently enter a second steam turbine ST2.
[0019] Downstream said first exchanger HEX1 said first
working-media-stream EXH1 is expanded in said second steam turbine
ST2, which is a high pressure steam turbine (high pressure means
that this pressure level is higher than the pressure level of the
downstream turbine--a first steam turbine ST1).
[0020] The first working-media-stream EXH1 exiting said second
steam turbine ST2 is divided in a second exhaust-fluid-stream or
second working-media-stream EXH2 and a third exhaust-fluid-stream
or third working-media-stream EXH3, wherein in particular
approximately above 90% of said first working-media-stream EXH1
becomes said third exhaust-fluid-stream EXH3.
[0021] Downstream said second steam turbine ST2 said third
working-media-stream EXH3 enters said first heat exchanger HEX1 to
be reheated taking thermal energy from said first
exhaust-fluid-stream EXH1 coming from said oxy-fuel-burner OXB.
[0022] The presence of the second steam turbine ST2 and the first
heat exchanger HEX1 may be optional.
[0023] Further downstream said third working-media-stream EXH3
enters a first steam turbine ST1 to be expanded from approximately
40 bar pressure down to a pressure of 0.2 bar. The pressure values
are meant as examples. Said first turbine ST1 comprises several
extractions of fluid streams so that said expanded third
working-media-stream EXH3 is reduced to a seventh
exhaust-fluid-stream or seventh working-media-stream EXH7 by
extraction of a fourth exhaust-fluid-stream or fourth
working-media-stream EXH4, extraction of a fifth
exhaust-fluid-stream or fifth working-media-stream EXH5 and
extraction of a sixth exhaust-fluid-stream or sixth
working-media-stream EXH6. Downstream said first steam turbine ST1
said seventh working-media-stream EXH7 is partly liquefied in a
first condenser CON1 (or more generally, in a water separator),
which is equipped with a degasifier to separate said seventh
working-media-stream EXH7 into a gaseous eighth
exhaust-fluid-stream or eighth working-media-stream EXH8 and a
liquid ninth exhaust-fluid-stream or ninth working-media-stream
EXH9 both exiting said first condenser CON1. Said eighth
working-media-stream EXH8 is basically gaseous carbon-dioxide and
further downstream compressed in an intercooled multistage
compressor MCP consisting of the stages CP1, CP2, CP3 and the
intercooling heat exchangers INT3, INT4. Said multistage compressor
MCP may receive further gaseous streams of carbon-dioxide at
several intermediate pressure levels of compression to be
compressed for subsequent usage, here indicated as storage STO.
[0024] Downstream said first condensers CON1 said ninth
working-media-stream EXH9 it delivered to a higher pressure level
by a first feed water pump FWP1, which has again an output of a
feed-water-pump-output-stream. At a downstream division point DIV1
(which can be located at many different positions in the cycle,
though) said ninth working-media-stream EXH9--more precisely: said
feed-water-pump-output-stream--is split into a tenth
exhaust-fluid-stream or tenth working-media-stream or
extraction-fluid-stream EXH10--which basically consists of liquid
water H.sub.2O--and an eleventh exhaust-fluid-stream or eleventh
working-media-stream EXH11, which enters a downstream mixing
pre-heater and degasifier MPD. In said mixing pre-heater and
degasifier MPD said eleventh working-media-stream EXH11 mixes with
said sixth working-media-stream EXH6 extracted from said first
steam turbine ST1 to increase the temperature and further mixes
with a 22nd exhaust-fluid-stream or 22nd working-media-stream
EXH22, which is throttled by a valve TH3 into said mixing
pre-heater and degasifier MPD. The gaseous amount generated in said
mixing pre-heater and degasifier MPD is directed to said multistage
compressor MCP as a twelfth exhaust-fluid-stream or twelfth
working-media-stream EXH12. The liquid amount from said mixing
pre-heater and degasifier MPD is delivered to a downstream second
feed-water-pump FWP2 as a thirteenth exhaust-fluid-stream or
thirteenth working-media-stream EXH13. Further downstream said
thirteenth working-media-stream EXH13 is heated-up in a second
sub-cooler SCO2 exchanging heat with said 22th working-media-stream
EXH22 before the latter enters said mixing pre-heater and
degasifier MPD. Further downstream said thirteenth
working-media-stream EXH13 enters in the following order a first
feed water pre-heater WPH1, a first (optional) sub-cooler SCO1, a
second (optional) feed water pre-heater WPH2, a third (optional)
heat exchanger HEX3 and a third (optional) feed water pre-heater
WPH3 and a second (optional) heat exchanger HEX2.
[0025] As already indicated the division point DIV1 can be
positioned also at other positions in the cycle.
[0026] Downstream this pre-heating sequence said thirteenth
working-media-stream EXH13 joins or leads into said recirculation
line RCL through an adjustable valve WSV to be injected into said
oxy-fuel-burner OXB to adjust the temperature of said first
working-media-stream EXH1 as said above mentioned cooling
media.
[0027] Said third feed water pre-heater WPH3 is heated by said
second working-media-stream EXH2 extracted from said second steam
turbine ST2 downstream passing said second heat exchanger HEX2
transferring thermal energy to said thirteenth working-media-stream
EXH13. Said third feed water pre-heater WPH3 splits the hot side of
this heat exchange into a gaseous component supplied to the
multistage compressor MCP as an eighteenth exhaust-fluid-stream or
eighteenth working-media-stream EXH18. The liquid component of the
hot side of the third feed water pre-heater WPH3 is provided as a
heating fluid through a first throttle TH1 into said second feed
water pre-heater WPH2 as 20.sup.th exhaust-fluid-stream or
20.sup.th working-media-stream EXH20.
[0028] Said second feed water pre-heater WPH2 subsequently receives
said fourth working-media-stream EXH4 from said first steam turbine
ST1 to heat-up said thirteenth working-media-stream EXH13.
[0029] Said second feed water pre-heater WPH2 discharges a gaseous
sixteenth exhaust-fluid-stream or sixteenth working-media-stream
EXH16--consisting basically of carbon-dioxide--and a liquid 21st
exhaust-fluid-stream or 21st working-media-stream EXH21 both
resulting from said incoming fourth working-media-stream EXH4 and
said 20.sup.th working-media-stream EXH20. Said 21st
working-media-stream EXH21 enters the heating side of said first
sub-cooler SCO1 and further downstream enters said first feed water
pre-heater WPH1 through a second throttle valve TH2 on the heating
side.
[0030] Partly already explained, said first feed water pre-heater
WPH1 receives said fifth working-media-stream EXH5 from said first
steam turbine ST1 to heat-up said thirteenth working-media-stream
EXH13.
[0031] Further, said first feed water pre-heater WPH1 discharges a
gaseous fourteenth exhaust-fluid-stream or fourteenth
working-media-stream EXH14--consisting basically of
carbon-dioxide--and the liquid 22nd working-media-stream EXH22 both
resulting from said incoming fifth working-media-stream EXH5 and
said 21st working-media-stream EXH21. Said 22nd
working-media-stream EXH22 enters the heating side of said second
sub-cooler SCO2 and further downstream enters said mixing
pre-heater and degasifier MPD through said third throttle valve TH3
on the heating side.
[0032] Said first steam turbine ST1 and said second steam turbine
ST2 both drive at least one generator GEN to produce electrical
power. As an alternative a direct drive can be provided for example
for a compressor or any other unit to be driven.
[0033] Said first condenser CON1 can be cooled by ambient air,
ambient water from a sea or a river or it can be a water spray
condenser cooling the fluid to be condensed by water jet. Water can
be provided by for example water extracted from said power
generation system cooled and re-injected.
[0034] To prevent accumulation of undesired products in the cycle a
water treatment WT can be inserted for example in said
recirculation line RCL or at another location in the cycle.
Alternatively or in addition (as shown in the FIGURE) another water
treatment WT can be inserted upstream of the extraction of water
H.sub.2O as the tenth extraction-fluid-stream EXH10. This location
would also improve the quality of water to be extracted for any
potential subsequent usage.
[0035] It has to be noted that the extraction-fluid-stream EXH10
could be extracted at a lot of different positions in the
cycle.
[0036] The steam cycle RC is operated with the
working-media-streams EXH1, EXH7, EXH9, EXH11, EXH13. New fluid is
provided via the first working-media-streams EXH1, some of the
fluid is also extracted from the cycle, e.g. working-media-streams
EXH8, EXH12, EXH14, EXH16, EXH18.
[0037] In an embodiment, the separation of carbon dioxide (CO2)
from the first feed water pre-heater WPH1 (or the other feed water
pre-heaters WPH2, WPH3) may differentiate from known feed water
preheaters found in other steam cycles, since the magnitude of gas
to be separated may be substantial, many percent of the steam
turbine extraction flow (here: EXH2 or EXH4 or EXH5), whereas in
known condensers just some ppb (part per billion) levels are
separated during normal operation.
[0038] Some of the features as explained in the embodiment above
are optional. The following setup is sufficient:
[0039] A power generation system PGS comprising--an oxy-fuel-burner
OXB, wherein said oxy-fuel-burner OXB is made to generate a first
burner-discharge-fluid from burning fuel F with an oxygen
containing gas O2, said oxygen containing gas O2 having oxygen
content which is higher than the oxygen content of ambient air, --a
recirculation line RCL for feeding a first liquid, particularly
water, into said oxy-fuel-burner OXB to mix with said generated
first burner-discharge-fluid to a first working-media-stream EXH1,
--a steam cycle RC operated with said first working-media-stream
EXH1, --wherein said steam cycle RC comprises at least one first
steam turbine ST1 expanding at least a part of said first
working-media-stream EXH1, namely a third working-media-stream
EXH3, wherein said first steam turbine ST1 has at least one output
port for expanded fluid, one of which providing a seventh
working-media-stream EXH7, --wherein said steam cycle RC comprises
at least one first water separator CON1, particularly a condenser,
downstream said first steam turbine ST1 condensing part of said
seventh working-media-stream EXH7, wherein said first water
separator CON1 has at least one output port for condensed fluid,
one of which providing a ninth working-media-stream EXH9, --wherein
said steam cycle RC comprises at least one first feed-water-pump
FWP1 downstream of said first water separator CON1 delivering said
ninth working-media-stream EXH9 to a higher pressure level, with an
output of a feed-water-pump-output-stream, wherein, said steam
cycle RC comprises at least one first feed-water pre-heater WPH1
downstream said first feed-water-pump FWP1 heating at least a part
of said feed-water-pump-output-stream, namely a thirteenth
working-media-stream EXH13, --wherein said steam cycle RC leads
into said recirculation line RCL downstream said at least one first
feed water pre-heater WPH1 feeding said thirteenth
working-media-stream EXH13 into said recirculation line RCL as said
first liquid, --wherein a part of working media in said steam cycle
RC is extracted from said steam cycle RC, particularly downstream
said first feed-water-pump FWP1, as a tenth extraction-fluid-stream
EXH10, said tenth extraction-fluid-stream EXH10 being particularly
water, --said first water separator CON1 further extracts
carbon-dioxide from said seventh working-media-stream EXH7 via a
further output port of said first water separator CON1 as an eighth
carbon-dioxide-stream EXH8, --wherein one of said output ports of
said first steam turbine ST1 provides a fifth working-media-stream
EXH5 and wherein said at least one first feed water-pre-heater WPH1
is heated via said fifth working-media-stream EXH5.
[0040] The following method steps will be performed for such a
system:
[0041] Method to operate a power generation system (PGS) defined by
the following steps: --generating a first burner-discharge-fluid
from burning an oxygen containing gas (O2) and fuel (F), --wherein
an oxygen content of said oxygen containing gas (O2) is higher than
the oxygen content of ambient air, --providing a steam cycle RC
comprising at least one first steam turbine ST1, at least one first
water separator CON1, particularly a condenser, downstream said
first steam turbine ST1, at least one first feed-water-pump FWP1
downstream said first water separator CON1, at least one first
feed-water-preheater WPH1 downstream said first feed-water-pump
FWP1, --extracting a part of working media from said steam cycle RC
by a recirculation line RCL and feeding a first liquid,
particularly water, as said part of said working media into said
oxy-fuel-burner OXB to mix with said generated first
burner-discharge-fluid to result in a first working-media-stream
EXH1, --operating said steam cycle RC with said first
working-media-stream EXH1, --expanding at least a part of said
first working-media-stream EXH1, namely a third
working-media-stream EXH3 by said at least one first steam turbine
ST1, --condensing at least a part of said expanded third
working-media-stream EXH3, namely a seventh working-media-stream
EXH7, by said at least one first water separator CON1, --delivering
at least a part of said seventh working-media-stream EXH7
downstream of said first water separator CON1 to a higher pressure
level, namely a ninth working-media-stream EXH9, by said at least
one first feed-water-pump FWP1, and outputting a
feed-water-pump-output-stream by said at least one first
feed-water-pump FWP1, --heating at least a part of said
feed-water-pump-output-stream, namely a thirteenth
working-media-stream EXH13 by at least one first
feed-water-preheater WPH1, --feeding at least a part of said
thirteenth working-media-stream EXH13 from said steam cycle RC as
said first liquid into said recirculation line RCL downstream said
at least one first feed water pre-heater WPH1, --extracting a part
of working media of said steam cycle RC from said steam cycle RC,
particularly downstream said first feed-water-pump FWP1, as a tenth
extraction-fluid-stream EXH10, said tenth extraction-fluid-stream
EXH10 being particularly water, --extracting a part of said seventh
exhaust-fluid-stream EXH7 as carbon-dioxide downstream said first
water separator CON1, namely an eighth carbon-dioxide-stream EXH8,
--heating said at least one first feed water-preheater WPH1 by an
output-stream extracted from said first steam turbine ST1, namely a
fifth working-media-stream EXH5.
[0042] Just in slightly different wording, the previously explained
system and method are substantially equivalent to the following
system and method (identical or similar elements are identified by
the same reference numerals):
[0043] Power generation system comprising--an oxy-fuel-burner
(OXB), wherein said oxy-fuel-burner (OXB) is made to generate
exhaust-fluid from burning fuel (F) with an oxygen containing gas
(O2), which's oxygen content is higher than the oxygen con-tent of
ambient air, --a steam cycle (RC) operated with said exhaust-fluid
generated by said oxy-fuel-burner (OXB), --a recirculation line
(RCL) extracting a part of said exhaust-fluid from said steam cycle
(RC) and feeding said exhaust-fluid-stream into said
oxy-fuel-burner (OXB) to mix with said continuously generated
exhaust-fluid, --wherein said steam cycle (RC) comprises at least
one first steam turbine (ST1) expanding at least a part of said
exhaust-fluid, namely a third exhaust-fluid-stream (EXH3),
--wherein said steam cycle (RC) comprises at least one first
condenser (CON1) downstream said first steam turbine (ST1)
condensing at least a part of said third exhaust-fluid-stream
(EXH3), namely a seventh exhaust-fluid-stream (EXH7), --wherein
said steam cycle (RC) comprises at least one first feed-water-pump
(FWP1) downstream of said first condenser (CON1) delivering at
least a part of said seventh exhaust-fluid-stream (EXH7) to a
higher pressure level, namely a ninth exhaust-fluid-stream (EXH9)
wherein, said steam cycle (RC) comprises at least one first
feed-water-preheater (WPH1) downstream said first feed-water-pump
(FWP1) heating at least a part of said seventh exhaust-fluid-stream
(EXH7), namely a thirteenth exhaust-fluid-stream (EXH13), --wherein
said steam cycle (RC) joins into said recirculation line (RCL)
downstream said at least one first feed water pre-heater (WPH1)
feeding at least a part of said thirteenth exhaust-fluid-stream
(EXH13) into said recirculation line (RCL), namely a nineteenth
exhaust-fluid-stream (EXH19), --wherein a part of said ninth
exhaust-fluid-stream (EXH9) is extracted from said steam cycle (RC)
downstream said first feed-water-pump (FWP1) as a tenth
exhaust-fluid-stream (EXH10), --wherein a part of said seventh
exhaust-fluid-stream (EXH8) is extracted as carbon-dioxide
downstream said first condenser (CON1), namely an eighth
exhaust-fluid-stream (EXH8), --wherein said at least one first feed
water-preheater (WPH1) is heated with an exhaust-fluid-stream
extracted from said first steam turbine (ST1), namely a fifth
exhaust-fluid-stream (EXH5).
[0044] The corresponding method will be executed on such a
system:
[0045] Method to operate a power generation system (PGS) defined by
the following steps: --generating exhaust-fluid from burning an
oxygen containing gas (O2) and fuel (F), --wherein an oxygen
content of said oxygen containing gas (O2) is higher than the
oxygen content of ambient air, --providing a steam cycle (RC)
comprising at least one first steam turbine (ST1), at least one
first condenser (CON1) downstream said first steam turbine (ST1),
at least one first feed-water-pump (FWP1) downstream said first
condenser (CON1), at least one first feed-water-preheater (WPH1)
downstream said first feed-water-pump (FWP1), --operating said
steam cycle (RC) with said exhaust-fluid generated by said
oxy-fuel-burner (OXB), --extracting a part of said exhaust-fluid
from said steam cycle (RC) by a recirculation line (RCL) and
feeding said exhaust-fluid-stream into said oxy-fuel-burner (OXB)
to mix with said continuously generated exhaust-fluid, --expanding
at least a part of said exhaust-fluid, namely a third
exhaust-fluid-stream (EXH3) by said at least one first steam
turbine (ST1), --condensing at least a part of said third
exhaust-fluid-stream (EXH3), namely a seventh exhaust-fluid-stream
(EXH7), by said at least one first condenser (CON1), --delivering
at least a part of said seventh exhaust-fluid-stream (EXH7)
downstream of said first condenser (CON1) to a higher pressure
level, namely a ninth exhaust-fluid-stream (EXH9), by said at least
one first feed-water-pump (FWP1), --heating at least a part of said
seventh exhaust-fluid-stream (EXH7), namely a thirteenth
exhaust-fluid-stream (EXH13) by at least one first
feed-water-preheater (WPH1), --feeding at least a part of said
thirteenth exhaust-fluid-stream (EXH13) from said steam cycle (RC)
into said recirculation line (RCL), namely a nineteenth
exhaust-fluid-stream (EXH19), downstream said at least one first
feed water pre-heater (WPH1), --extracting a part of said ninth
exhaust-fluid-stream (EXH9) from said steam cycle (RC) downstream
said first feed-water-pump (FWP1) as a tenth exhaust-fluid-stream
(EXH10), --extracting a part of said seventh exhaust-fluid-stream
(EXH8) as carbon-dioxide downstream said first condenser (CON1),
namely an eighth exhaust-fluid-stream (EXH8), --heating said at
least one first feed water-preheater (WPH1) by an
exhaust-fluid-stream extracted from said first steam turbine (ST1),
namely a fifth exhaust-fluid-stream (EXH5).
* * * * *