Thermal integration of a carbon dioxide capture and compression unit with a steam or combined cycle plant

Abstract

A power plant system including a fossil fuel fired power plant (6) for the generation of electricity, a carbon dioxide capture and compression system (5, 13), and an external heat cycle system has at least one heat exchanger (1,2,3) for the heating of the flow medium of the external heat cycle system. The heat exchanger (1,2,3) is connected to a heat flow from the CO.sub.2 capture plant (5) or a CO.sub.2 compression unit (13). A return flow from the heat exchanger (1,2,3) is led to the CO.sub.2 capture and compression system (5,13) or to the power plant (6). The power plant system allows an increase in overall efficiency of the system.

Claims

1. A method for operation of a power plant system including a power plant for generation of electricity, an external heat cycle system, and a carbon dioxide capture and compression system, the carbon dioxide capture and compression system comprising a carbon dioxide capture plant and a carbon dioxide compression unit, the method comprising: operating the carbon dioxide capture plant to absorb carbon dioxide from exhaust gases of the power plant with an absorber solution and release the absorbed carbon dioxide from the absorber solution to form a carbon dioxide gas stream and an absorber solution by directing the absorber solution through a reboiler; forwarding the carbon dioxide gas stream to the carbon dioxide compression unit configured to compress and cool the carbon dioxide gas stream; operating a main heat exchanger to transfer heat from a steam flow extracted from the power plant to a flow medium of the external heat cycle system and direct a return flow from the main heat exchanger to a water steam cycle of the power plant; transferring heat from the carbon dioxide capture plant and the carbon dioxide compression unit to the flow medium of the external heat cycle system with at least one additional heat exchanger, wherein the least one additional heat exchanger comprises a first heat exchanger, a second heat exchanger, and a third heat exchanger; and directing a return flow from the first heat exchanger of the at least one additional heat exchanger to the power plant; and directing a return flow from the third heat exchanger of the at least one additional heat exchanger to the carbon dioxide compression unit.

2. The method according to claim 1, further comprising: operating the at least one additional heat exchanger for the cooling of carbon dioxide in the carbon dioxide compression unit; directing a flow from the first heat exchanger of the at least one additional heat exchanger to the second heat exchanger of the at least one additional heat exchanger; operating the second heat exchanger of the at least one additional heat exchanger to transfer heat to the flow medium of the external heat cycle system; and directing a first return flow from the second heat exchanger of the at least one additional heat exchanger to a cooling cycle for compressed carbon dioxide operatively connected to the carbon dioxide compression unit.

3. The method according to claim 2, further comprising: operating the second heat exchanger of the at least one additional heat exchanger in series with the main heat exchanger; and operating the main heat exchanger downstream of the second heat exchanger of the at least one additional heat exchanger in the direction of the flow medium of the external heat cycle system.

4. The method according to claim 2, further comprising: directing a condensate flow from the reboiler to the first heat exchanger of the at least one additional heat exchanger for heat exchange with the flow medium of the external heat cycle system; and directing a second return flow from the first heat exchanger of the at least one additional heat exchanger as a condensate flow to the water steam cycle of the power plant; wherein the first heat exchanger of the at least one additional heat exchanger and the second heat exchanger of the at least one additional heat exchanger are operated in series.

5. The method according to claim 1, further comprising: directing a carbon dioxide flow generated by the carbon dioxide capture plant to the third heat exchanger of the at least one additional heat exchanger; operating the third heat exchanger of the at least one additional heat exchanger to transfer heat from the carbon dioxide flow to the flow medium of the external heat cycle system; and directing a carbon dioxide flow returning from the third heat exchanger to the carbon dioxide compressing unit.

6. The method according to claim 5, further comprising: operating the third heat exchanger of the at least one additional heat exchanger in series with the main heat exchanger; and operating the main heat exchanger downstream of the third heat exchanger of the at least one additional heat exchanger in the direction of the flow medium of the external heat cycle system.

7. The method according to claim 5, further comprising: directing a return condensate flow from the reboiler to the first heat exchanger of the at least one additional heat exchanger for heat exchange with the flow medium of the external heat cycle system; and directing a second return flow from the first heat exchanger of the at least one additional heat exchanger as a condensate flow to the water steam cycle of the power plant; wherein the first heat exchanger of the at least one additional heat exchanger and the third heat exchanger of the at least one additional heat exchanger are operated in series.

8. The method according to claim 5, further comprising: operating the at least one additional heat exchanger for the cooling of carbon dioxide in the carbon dioxide compression unit; directing the second return flow from the at least one additional heat exchanger to the second heat exchanger of the at least one additional heat exchanger; operating the second heat exchanger of the at least one additional heat exchanger to transfer heat to the flow medium of the external heat cycle system; and directing a first return flow from the second heat exchanger of the at least one additional heat exchanger to a cooling cycle operatively connected to the carbon dioxide compression unit; wherein the second heat exchanger of the at least one additional heat exchanger and the third heat exchanger of the at least one additional heat exchanger are operated in series.

9. The method according to claim 5, further comprising: directing a condensate flow from the reboiler to the first heat exchanger of the at least one additional heat exchanger for heat exchange with the flow medium of the external heat cycle system; directing a second return flow from the first heat exchanger of the at least one additional heat exchanger as a condensate flow to the water steam cycle of the power plant; operating at least one heat exchanger of the at least one additional heat exchanger for the cooling of carbon dioxide in the carbon dioxide compression unit; directing the second return flow from the first heat exchanger of the at least one heat exchanger of the at least one additional heat exchanger to the second heat exchanger of the at least one additional heat exchanger; operating the second heat exchanger of the at least one additional heat exchanger to transfer heat to the flow medium of the external heat cycle system; and directing the first return flow from the second heat exchanger of the at least one additional heat exchanger to a cooling cycle operatively connected to the carbon dioxide compression unit wherein the first heat exchanger of the at least one additional heat exchanger and the second heat exchanger of the at least one additional heat exchanger and the third heat exchanger of the at least one additional heat exchanger are operated in series.

10. A power plant system comprising: a power plant configured and arranged to generate electricity, the power plant including a steam extraction; a carbon dioxide capture and compression system, the carbon dioxide capture and compression system comprising a carbon dioxide capture plant and a carbon dioxide compression unit, the carbon dioxide capture plant configured to maintain a cycle comprising an absorber solution configured and arranged to absorb carbon dioxide from exhaust gases of the power plant, and a reboiler configured and arranged to receive and heat the absorber solution and release the absorbed carbon dioxide to at least one of the carbon dioxide capture plant; wherein concentrated carbon dioxide released from the carbon dioxide capture plant is passed to the carbon dioxide compression unit; an external heat cycle system; a main heat exchanger configured and arranged to heat flow medium of the external heat cycle system, wherein the power plant is operatively connected to the external heat cycle system by the steam extraction from the power plant and the main heat exchanger; at least one additional heat exchanger comprising a first heat exchanger, a second heat exchanger, and a third heat exchanger, configured and arranged to heat the flow medium of the external heat cycle system with at least one heat flow generated by the carbon dioxide capture plant and the compression unit from a carbon dioxide gas, the at least one additional heat exchanger being configured and arranged to direct a return flow to the power plant and carbon dioxide compression unit, the at least one additional heat exchanger arranged at least one of in series upstream of the main heat exchanger.

11. The power plant system according to claim 10, wherein the power plant system comprises a water steam, a first line configured and arranged to direct a flow of condensate from the reboiler to the first heat exchanger of the at least one additional heat exchanger; and a second line configured and arranged to return condensate from the first heat exchanger of the at least one additional heat exchanger to the water steam cycle of the power plant.

12. The power plant system according to claim 11, wherein: the first heat exchanger of the at least one additional heat exchanger is arranged in series with the main heat exchanger; and the main heat exchanger is arranged downstream of the first heat exchanger of the at least one additional heat exchanger in the direction of flow medium of the external heat cycle system.

13. The power plant system according to claim 10, wherein the second heat exchanger of the at least one additional heat exchanger is configured and arranged to heat flow medium of the external heat cycle system, and further comprising: a cooling tower; a cooling cycle for compressed carbon dioxide operatively connected to the carbon dioxide compression unit; a third line configured and arranged to direct cooling medium of a carbon dioxide compression and cooling unit from the cooling tower to the second heat exchanger of the at least one additional heat exchanger; and a fourth line configured and arranged to return flow from the second heat exchanger of the at least one additional heat exchanger to the cooling cycle operatively connected to the carbon dioxide compression unit.

14. The power plant system according to claim 13, wherein: the second heat exchanger of the at least one additional heat exchanger is arranged in series with the main heat exchanger; and the main heat exchanger is arranged downstream of the second heat exchanger of the at least one additional heat exchanger in the direction of flow medium of the external heat cycle system.

15. The power plant system according to claim 13, wherein the power plant comprises a water steam cycle, and further comprising: a first line configured and arranged to direct a flow of condensate from the reboiler to the first heat exchanger of the at least one additional heat exchanger; and a second line configured and arranged to return condensate from the first heat exchanger of the at least one additional heat exchanger to the water steam cycle of the power plant; wherein the first heat exchanger of the at least one additional heat exchanger and the second heat exchanger of the at least one additional heat exchanger are arranged in series with respect to flow medium of the external heat cycle system.

16. The power plant system according to claim 10, wherein the carbon dioxide capture and compression system comprises the carbon dioxide compression unit, and the third heat exchanger of the at least one additional heat exchanger is configured and arranged to heat flow medium of the external heat cycle system with a carbon dioxide flow generated by the carbon dioxide capture plant, and further comprising: a line leading from the carbon dioxide capture plant to the third heat exchanger of the at least one additional heat exchanger; and a further line leading from the third heat exchanger of the at least one additional heat exchanger to the carbon dioxide compression unit.

17. A power plant system according to claim 16, wherein: the third heat exchanger of the at least one additional heat exchanger is arranged in series with the main heat exchanger; and the main heat exchanger is arranged downstream of the third heat exchanger of the at least one additional heat exchanger in the direction of flow medium of the external heat cycle system.

18. The power plant system according to claim 16, wherein the power plant comprises a water steam cycle, and further comprising: a first line configured and arranged to return condensate from the reboiler to the first heat exchanger of the at least one additional heat exchanger; and a second line configured and arranged to return condensate from the first heat exchanger of the at least one additional heat exchanger to the water steam cycle of the power plant; wherein the first heat exchanger of the at least one additional heat exchanger and the third heat exchanger of the at least one additional heat exchanger are arranged in series with respect to the flow medium of the external heat cycle system.

19. A power plant system according to claim 16, wherein the second heat exchanger of the at least one additional heat exchanger configured and arranged to heat flow medium of the external heat cycle system, and further comprises: a cooling tower; a cooling cycle operatively connected to the carbon dioxide compression unit; a third line configured and arranged to direct cooling medium of a carbon dioxide compression and cooling unit leading from the cooling tower to the second heat exchanger of the at least one additional heat exchanger; and a fourth line configured and arranged to return flow from the second heat exchanger of the at least one additional heat exchanger to the cooling cycle operatively connected to the carbon dioxide compression unit; wherein the second heat exchanger of the at least one additional heat exchanger and the third heat exchanger of the at least one additional heat exchanger are arranged in series with respect to the flow medium of the external heat cycle system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Preferred embodiments of the invention are described in the following with reference to the drawings, which illustrate exemplary embodiments of the present invention and shall not be considered to limit the scope of protection. In the drawings,

(2) FIG. 1 shows a power plant according to the prior art including a steam power plant or a combined cycle power plant, a carbon dioxide capture and compression plant, and an external heat cycle system.

(3) FIG. 2 shows a power plant according to a first embodiment to the invention including a steam power plant or a combined cycle power plant with a carbon dioxide capture and compression system thermally integrated with an external heat cycle system by a first heat exchanger;

(4) FIG. 3 shows a power plant according to a second embodiment to the invention including a steam power plant or a combined cycle power plant with a carbon dioxide capture and compression system thermally integrated with an external heat cycle system by a second heat exchanger;

(5) FIG. 4 shows a power plant according to a third embodiment to the invention including a steam power plant or a combined cycle power plant with a carbon dioxide capture and compression system thermally integrated with an external heat cycle system by a third heat exchanger;

(6) FIG. 5 shows a power plant according to a further embodiment to the invention including a steam power plant or a combined cycle power plant with a carbon dioxide capture and compression system thermally integrated with an external heat cycle system by a combination of heat exchangers;

(7) FIG. 6 shows a power plant according to a further embodiment to the invention including a steam power plant or a combined cycle power plant with a carbon dioxide capture and compression system thermally integrated with an external heat cycle system by a further combination of heat exchangers.

(8) In the figures elements with same reference numerals designate the same elements and fulfill the same function unless described otherwise.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

(9) FIG. 2 shows a power plant 6 with a CO.sub.2 capture plant 5 having a line 27 for flue gas leading from the power plant to the CO.sub.2 capture plant 5, a line 20 leading the extracted CO.sub.2 away from the capture plant 5, and a line 29 releasing flue gas free of CO.sub.2. An absorber solution cycle includes a line 26 for the absorber solution leading from the capture plant to a reboiler 4 for the absorber solution. A steam extraction line 23 directs steam for the operation of the reboiler 4 from the power plant's water steam cycle, for example from the heat recovery steam generator, and a line 25 leads return condensate away from the reboiler 4. The line 20 for the CO.sub.2 extracted extends from the CO.sub.2 capture plant to a precooler 12, which is arranged prior to the CO.sub.2 compression unit 13.

(10) The power plant of FIG. 2 includes an integration of the power plant and CO.sub.2 capture and compression and cooling system with an external heat cycle system. The heat cycle system includes a cycle line 28 for a medium to be heated, for example water, a source unit 11, and a user 19, to which the heated outflow of the cycle is directed. The embodiment according to FIG. 2 includes a line 25 directing the return condensate flow from the amine reboiler 4 to a first heat exchanger 1 configured and arranged for heating a flow medium in line 28 of the external heat cycle system. In the heat exchanger 1, the heat contained in the condensate may be transferred to the flow medium in line 28. The return flow of the heat exchanger 1 is directed via line 25 to line 24, which directs the feedwater back to the power plant 6.

(11) The typical temperature range of the condensate flow resulting from the amine reboiler 4 can range from 160 C.-100 C.

(12) The configuration according to this embodiment of the invention contributes in multiple ways to the overall efficiency of the power plant. Compared to the plant configuration in FIG. 1, the temperature level of the return flow back to the water steam cycle is reduced. Thereby, the heat available in the HRSG or boiler may be used more effectively and the overall thermal efficiency of the power plant and external heat cycle system is increased. Due to the integration of the CO.sub.2 capture plant with the external heat cycle system by heat exchanger 1, the remaining heat from the reboiler 4 is used to contribute heat to the external cycle system. The temperature of the flow in line 28 at the outflow to the user 19 of the cycle system is generally given at a required level. In order to reach that required temperature level in line 28 at user 19, the main heat exchanger CHEX in FIG. 2 has to contribute less than the heat exchanger HEX in the configuration of FIG. 1. Thereby, the massflow of the steam extraction 17 for the main heat exchanger CHEX can be reduced. Consequently, the power plant 6 suffers less energy loss and can operate at a higher efficiency.

(13) FIG. 3 shows a further power plant with CO.sub.2 capture and compression system and an integrated external heat cycle system. The flow medium of the external heat cycle system is heated by the main heat exchanger CHEX, which is provided by the steam extraction 17 from the water steam cycle of the power plant. In addition, it is heated by a heat exchanger 2 arranged in the heat cycle upstream from the main heat exchanger. The heat exchanger 2 is provided with heat from the flow for cooling the CO.sub.2 extracted by the capture system 5. The return flow of the cooling medium for a precooler 12 and from several intercoolers 7 arranged between the several CO.sub.2 compressors 15 is directed via line 8 to the heat exchanger 2. The temperature of the flow in line 8 may be about 100 C. The cooling cycle of the carbon dioxide compression unit 13 is thus used actively for heat transfer to the client network 11. This is most efficiently done as illustrated in FIG. 3 by using the cooling water lines 8 essentially just upstream of the cooling tower 9, so where the cooling medium in the cycle 8 has the highest temperature, for heat exchange with the water in line 28 of the client network in a heat exchanger 2. Heat exchanger 2 is preferably arranged upstream of the conventional heat exchanger CHEX with respect to the flow of the cooling medium in cycle 8.

(14) The return flow from this heat exchanger 2 is then directed to a cooling facility 9. Heat gained from the CO.sub.2 cooling is put to use in the heat cycle system. The heat exchanger 2 transfers heat to the cycle system and as such supports the main heat exchanger CHEX. In order to reach a required temperature of the flow medium in line 28 for user 19, the main heat exchanger CHEX in FIG. 3 needs less heat compared to the main heat exchanger shown in the power plant in FIG. 1. By the arrangement of heat exchanger 2, the massflow of the steam extraction in line 17 may be reduced and the efficiency of the power plant increased.

(15) FIG. 4 shows another embodiment of the power plant according to principles of the present invention, where a heat exchanger 3 is arranged in the external heat cycle system, upstream of the main heat exchanger CHEX. Heat from the carbon dioxide flow extracted by the carbon capture plant 5 is used for heating purposes in the external cycle system. For this, a carbon dioxide line 20 between the carbon dioxide capture plant 5 and the carbon dioxide compressor unit 13, which transports the carbon dioxide at an elevated temperature, is directed to the heat exchanger 3 prior to being directed to the precooler 12 and the compressor unit 13.

(16) In the heat exchanger 3, heat from the CO.sub.2 flow is transferred to the flow in line 28 of a client network. Downstream of heat exchanger 3, in order to allow for different operational regimes, the line 21 is coupled to pre-cooler 12 prior to being fed via line 22 to the first stage of the compressor 15. The pre-cooler 12 serves as a back-up cooler for the CO.sub.2. Heat exchange in the back-up cooler 12 takes place by coupling to the cooling circuit 8 of the compressor unit 13.

(17) An idea embodied in the system illustrated in FIG. 4 thus hinges again upon using heat from the CO.sub.2 Capture and Compression system (CCS) in order to increase the overall power plant efficiency. The thermal integration of the CCS with the power plant includes the integration and transfer, either direct or indirect, of heat from the CCS to a client network 11 requiring heat by the CO.sub.2 condenser or heat exchanger 3 located between the CO.sub.2 capture plant 5 (more precisely downstream of the regenerator column) and the CO.sub.2 compressor unit 13 (before the first compression stage). The client network 11 is an external consumer of the power plant that requires heat, such as a district heating, a greenhouse heating, biomass, or any industrial applications.

(18) Heat exchanger CHEX is required downstream of the CO.sub.2 condenser or heat exchanger 3. The heat exchanger CHEX is basically fed by steam in line 17 extracted from the main steam turbine, as for typical heat exportation. The steam can be extracted at different pressure levels, which will require different heat exchangers in series. This heat exchanger CHEX is used as a heater if the heat integrated by the CO.sub.2 condenser 3 is not sufficient to cover the requirements of the client network 11 (in terms of temperature and/or heat load) or if the CO.sub.2 capture and compression unit is not in operation at all. It should be designed to cover the requirements of the client network 11 when the integrated the CO.sub.2 condenser 3 is not in operation. The heat load required by the client's network 11 and the temperature of the water delivered to the client network is controlled by the steam extraction from low pressure steam turbine steam extraction, from an intermediate pressure-low pressure cross-over pipe, or from low pressure steam of a heat recovery steam generator. This steam can have a pressure level from 1 bar up to 5 bar.

(19) Heat exchanger CHEX can be either one heat exchanger supplied by one pressure level, or two heat exchangers in sequence that have two different steam supply pressure levels where the load distribution of the two heaters can be controlled according to the heat demand from the client network and the plant operation, for example during part load operation.

(20) Another backup cooler 12 that is provided with by main cooling water 8 can be installed between the heat exchanger 3 and the CO.sub.2 compressor 13. This additional cooler 12 ensures the cooling of the CO.sub.2 if the network is not in operation or if its lowest water temperature is too high to make sure that the CO.sub.2 is low enough to meet the temperature requirements of the CO.sub.2 compressor unit 13.

(21) The typical temperature range of the CO.sub.2 upstream of the CCS captured CO.sub.2 condenser 3 can be 80 C. up to 150 C. The typical temperature range of the flow of the external heat system or client network downstream of the CO.sub.2 condenser 3 can range from 70 C. to 140 C.

(22) The heat load of the CO.sub.2 condenser 3 is a function of the temperature of the cooling water 8, the load of the power plant 6, and the load of the CO.sub.2 capture plant 5. It is typically about 5 MWth up to 80 MWth for a combined cycle plant and about 5 MWth up 350 MWth for a steam plant.

(23) A combination of a heat exchanger 3, a main heat exchanger CHEX, and a heat exchanger 12 allows a great versatility in the operation of the power plant with CO2 capture, that is in regard to different modes of operation under different load conditions of the power plant 6, the carbon dioxide recovery 5, and the client network 11, respectively.

(24) The following operation concepts for the CCS captured CO.sub.2 condenser 3 and the main heat exchanger(s) CHEX are facilitated by a setup according to FIG. 4 and very generally in the context of using a heat exchanger 3, a main heat exchanger CHEX, and a heat exchanger or precooler 12.

(25) a) Operation of the power plant 6 and carbon dioxide capture 5 at full load, the client network 11 at full or part load:

(26) CO.sub.2 condenser or heat exchanger 3 at full load for client's network heat exchanger, further cooling of the captured CO.sub.2 stream downstream of the CCS captured CO.sub.2 condenser 3 by backup condenser 12, the steam fed heater(s) CHEX will work under full load or part load (e.g., with reduced steam extraction) depending on the heating load requirement of client network 11.

(27) b) Operation of the power plant 6 and carbon dioxide capture 5 at part load, client network 11 at full or part load:

(28) CO.sub.2 condenser or heat exchanger 3 operating at full load, further cooling of the captured CO.sub.2 flow downstream of heat exchanger 3 by heat exchanger or precooler 12, which functions as a backup heat exchanger, steam fed heat exchanger CHEX operates at full load or part load (e.g., with reduced steam extraction massflow) depending on heating load requirement of the external heat cycle system 11.

(29) c) Operation of the power plant 6 at full load or part load, while the carbon dioxide capture plant 5 is shut down, and the client network 11 operating full or part load:

(30) The external heat cycle system's load will be satisfied by heat exchanger CHEX. If heat exchanger CHEX is a two-stage heat exchanger system with two different steam pressure levels, distribution of heat load between the two heaters will depend on the power plant load 6 and the external heat cycle system's 11 heat load, and the minimized exergy losses due to steam extraction from power plant.

(31) d) Operation of the power plant 6 and carbon dioxide capture 5 at full load or part load, while client network 11 is shut-down:

(32) The CO.sub.2 condenser or heat exchanger 3 is bypassed, the backup condenser or precooler 12 operates to full to provide full precooling of CO.sub.2 prior to compression in unit 13.

(33) A further example of the thermal integration of the power plant and CO.sub.2 capture plant with an external heat cycle system is illustrated in FIG. 5. It includes a combination of the integration of the first heat exchanger 1 and the third heat exchanger or CO.sub.2 condenser 3, together with the precooler 12 and the conventional heat exchanger CHEX operated by steam extraction from the power plant.

(34) This specific combination of the four heat exchangers 1,3,12, and CHEX provides for even more efficient and more versatile transfer of heat from the power plant and heat generated by the carbon dioxide capture and compression process to the client network 11.

(35) Heat required for the heating of the flow in line 28 of the external heat cycle system is provided by both the CO2 condenser 3 and the heat exchanger 1 transferring the heat from the condensate resulting from amine reboiler 4. This results in a yet lower requirement for the temperature and pressure of the steam extracted from the power plant for the conventional heat exchanger CHEX. The condensate produced in the amine reboiler 4 will be sub-cooled by heat exchanger 3. The return flow from heat exchanger 3 together with the return flow from the conventional heat exchanger CHEX will have a yet lower temperature level when it enters via line 18 back to the HRSG or boiler of the power plant 6. Thereby, the heat available in the HRSG is again used more effectively in reheating the flow of line 18.

(36) The heat exchangers CHEX, 1, and 3 can be arranged in series, where heat exchangers 1 and 3 are arranged upstream of heat exchanger CHEX, as illustrated in FIG. 5. They can also be arranged in parallel, or in a combination of parallel and series arrangements.

(37) Several operation concepts for the CO.sub.2 condenser 3, heat exchanger 1 and conventional heat exchanger CHEX, as arranged for example in a power plant according to FIG. 5 or any of its possible variants are possible.

(38) a) Operation of power plant 6 and carbon dioxide capture 5 at full load, operation of the client network 11 at full or part load:

(39) The CO.sub.2 condenser or heat exchanger 3 operates at full load, further cooling of the captured CO.sub.2 flow downstream of the CO.sub.2 condenser 3 is provided by backup heat exchanger or precooler 12. If the heat load of the client network 11 decreases, first the heat load of the conventional heat exchanger CHEX will be reduced until shut-down; if the heat load of the client network 11 further decreases, the heat load from heat exchanger 1 will be reduced.

(40) b) Operation of both the power plant 6 and carbon dioxide capture plant 5 at part load, client network 11 at full or part load:

(41) Heat exchanger 3 operates at full load for client's network 11. The CO.sub.2 flow from the CO.sub.2 capture plant 5 is cooled further by the backup condenser or precooler 12. If the heat load from network 11 is reduced, the heat load from the conventional heat exchanger CHEX will be reduced first until shut-down; if the heat load from client network 11 reduces further, the heat load of heat exchanger 1 will then be reduced.

(42) c) Operation of the power plant 6 at full load or part load, shut-down of the carbon dioxide plant 5, operation client network 11 at full load or part load:

(43) The client's heat load will be provided by the conventional heater(s) CHEX. If heaters CHEX are of a two-stage heat exchanger design with two different steam pressures, the heat load will be distributed between the two heaters of CHEX depending on the power plant load 6 and the heat load of client's network 11 and the minimized exergy losses due to steam extraction from power plant 6.

(44) d) Operation of both the power plant 6 and operation of the carbon dioxide recovery 5 at full load or part load, shut-down of client network 11:

(45) Heat exchanger 3 and heat exchanger 1 will be bypassed, 100% of CO.sub.2 cooling performed by backup heat exchanger or precooler 12. The return condensate from the amine reboiler 4 goes directly back to the power plant 6.

(46) A further embodiment of the integration of CO.sub.2 capture plant 5 with power plant 6 and external heat cycle system 11 is illustrated in the schematic of FIG. 6.

(47) This power plant system includes all the of the first, second, and third heat exchangers 1, 2, and 3 in addition to the convention heat exchanger CHEX arranged to heat the flow of the external heat cycle system and thereby putting to use all of the possibilities of integrating the heat available from the CO.sub.2 capture and compression and cooling system in the external heat cycle system. The arrangement of FIGS. 2, 3, and 4 are thereby integrated in one power plant. By this integration, heat from the return condensate of the amine reboiler 4 together with the heat from the CO.sub.2 condenser 3 and the heat from the cooling medium inline 8 of the CO.sub.2-precooler 12 and CO.sub.2-intercoolers 7 is all used to heat the flow medium of the heat cycle system 11. Thereby, the benefit of reducing the steam extraction massflow in line 17 can be increased and the operation of the HRSG made more effective.

(48) The heat exchangers as shown in FIGS. 2-6, can be arranged in the client network line 28 depending on the specific relative temperature levels of their flow media in order to allow for the most efficient heat transfer between the individual cycle heat exchangers. In FIGS. 2-6, the heat exchangers may be arranged in different series arrangements as well as in different parallel arrangements. Also the heat exchangers CHEX, 1, 2, 3, may be realized by several individual heat exchanger apparatuses arranged in parallel or in series.

(49) Instead of only integrating the heat of the heat exchanger 3, the CO.sub.2 inter coolers and after-cooler 7 can also be integrated, either directly or indirectly, into the client network 11 by the heat exchanger 2 and the intermediate loop of cooling water 8. The intermediate loop 8 is needed to ensure the protection of the main condensate from a CO.sub.2 leakage at the CO.sub.2 inter-coolers or after-cooler. The cooling tower 9 (or another cooling device) is still needed to finalize the cooling if the inlet temperature from the client network 11 is too high or if the district heating is not in operation. This will ensure a good efficiency of the CO.sub.2 compressor unit 13.

(50) The heat exchangers 2 and 3 can be arranged in series or in parallel.

(51) The typical temperature range of the CO.sub.2 upstream of the CO.sub.2 inter-coolers and after-cooler 7 is in the range of 100 C.-230 C., depending on the inlet temperature and on the arrangement of the coolers.

(52) The following operation concepts for the heat exchanger 2 in a setup according to FIG. 3 are possible:

(53) a) Power plant 6 and carbon dioxide recovery 5 at full load or part load, client network 11 at full load or part load:

(54) Certain rate integrated by heat exchanger 2, the rest to backup cooling device 9.

(55) b) Power plant 6 and carbon dioxide recovery 5 at full load or part load, client network 11 shut-down:

(56) Heat exchanger 2 is bypassed, 100% on backup cooling device 9.

(57) The operation concepts for the CO.sub.2 condenser 3 and the heater(s) CHEX for such a setup according to FIG. 6 are analogous to the ones discussed with respect to other figures.

LIST OF REFERENCE SIGNS

(58) CHEX conventional heat exchanger using steam extraction from steam power plant for external heat cycle system 1 first heat exchanger using heat from amine reboiler of carbon capture plant 2 second heat exchanger using heat from CO.sub.2 compression and cooling unit 3 third heat exchanger using heat from carbon capture plant 4 amine reboiler 5 carbon dioxide capture plant 6 power plant 7 intercooler in CO.sub.2 compression unit 8 cooling water lines for CO.sub.2 compression and cooling unit 9 cooling tower 10 carbon dioxide storage facility 11 from client network 12 backup cooler 13 carbon dioxide compression and cooling unit 15 compressor 16 pump 17 steam extraction from the steam turbine of power plant 18 recirculation line, condensate return 19 to client network 20 line for CO.sub.2 flow from carbon dioxide capture plant to carbon dioxide compressor unit 21 line for CO.sub.2 flow to CO.sub.2 precooler 22 line for CO.sub.2 flow from CO.sub.2 precooler to CO.sub.2 compressor 23 steam extraction line to amine reboiler 24 line for return condensate from amine reboiler 25 line for return condensate from amine reboiler 25 line for return condensate to the first heat exchanger 25 line from first heat exchanger to feedwater pump 26 line for amine solution 27 flue gas line 28 line for external heat cycle system, e.g. district heating water 29 flue gas free of CO.sub.2 M motor

(59) While the invention has been described in detail with reference to exemplary embodiments thereof, it will be apparent to one skilled in the art that various changes can be made, and equivalents employed, without departing from the scope of the invention. The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents. The entirety of each of the aforementioned documents is incorporated by reference herein.