Systems and methods for steam supply to gas capture system during shutdown

Abstract

The system may include a gas capture system (20) containing a separation material—the gas capture system is configured to operate a regeneration process during partial load operation and / or shutdown operation to desorb undesirable gases from the separation material and regenerate the separation material for an absorption process—a heat recovery steam generator (16) configured to receive exhaust gas and generate steam, and a backup line (160) fluidically coupling the gas capture system to the heat recovery steam generator (HRSG)—the backup line is configured to provide steam from the HRSG (16) to the gas capture system (20) for the regeneration process during partial load operation and / or shutdown operation.

Description

Background Technology

[0001] The present application generally relates to a system and method for supplying steam to a gas capture system during a controlled shutdown operation of a combustion system, e.g., a combustion-driven power plant. The present invention, as claimed herein, relates to the subject matter described in the appended claims.

[0002] Industrial plants, such as combustion-driven power plants, can generate various gases, such as exhaust gases from combustion systems. Combustion systems may include gas turbine engines, reciprocating piston-cylinder engines, furnaces, boilers (e.g., heat recovery steam generators (HRSGs)), steam turbines, or other industrial equipment. These exhaust gases may contain one or more unwanted gases, such as acidic gases and / or greenhouse gases. For example, an undesirable gas is carbon oxides (CO₂). X ), for example, carbon dioxide (CO2) and carbon monoxide (CO), nitrogen oxides (NO X ), for example, nitrogen dioxide (NO2), and / or sulfur oxides (SO₂) X), may include, for example, sulfur dioxide (SO2). In certain cases, the combustion-driven power plant may include a gas capture system that enables the capture of undesirable gases during the operation of the combustion-driven power plant. The gas capture system may perform a regeneration operation to remove (e.g., stripping, desorption) undesirable gases from the separation material by, for example, applying heat to the separation material (e.g., adsorbent material of the adsorber and / or solvent of the stripper). Unfortunately, during the shutdown operation of the combustion-driven power plant, the regeneration of the separation material is generally incomplete due to a lack of heat. As a result, during the subsequent startup operation of the combustion-driven power plant, the previous incomplete regeneration of the separation material leads to a reduced gas capture rate in the gas capture system. Therefore, it is necessary to improve regeneration during the shutdown operation, for example, by providing additional heat to complete the regeneration.

[0003] The invention claimed herein is set forth in the appended claims. Certain embodiments corresponding to the subject and category originally claimed are summarized below. These embodiments are not intended to limit the scope of the claimed subject, but rather are intended merely to provide a brief overview of possible forms of the subject. In practice, the subject may include various forms that may be similar or different from the embodiments presented below.

[0004] In one embodiment, the system may include a gas capture system comprising a separation material—the gas capture plant is configured to regenerate the separation material for an absorption process by operating a regeneration process during partial load operation and / or shutdown operation to desorb undesirable gases from the separation material—a heat recovery steam generator (HRSG) configured to receive exhaust gas and generate steam, and a backup line fluidically coupled to the gas capture system to the HRSG—the backup line is configured to provide steam from the HRSG to the gas capture system for the regeneration process during partial load operation and / or shutdown operation. More specifically, the system may include a main extraction line fluidically coupled to or branched from the heat recovery steam generator and configured to provide steam from the heat recovery steam generator to the gas capture system. The backup line is also fluidly coupled to or branched from the heat recovery steam generator at at least one steam extraction location that provides a higher steam pressure than the steam extraction location to which the main extraction line is coupled to or branched from the heat recovery steam generator. For example, the main extraction line may branch off a line configured to supply steam to a low pressure (LP) steam turbine or a low pressure steam turbine section, while the backup line may branch off a line configured to supply high pressure steam from a heat recovery steam generator to a high pressure (HP) steam turbine or a high pressure steam turbine section and / or a line configured to supply steam from a high pressure steam turbine or a high pressure steam turbine section to a heat recovery steam generator and / or a line configured to supply steam from a heat recovery steam generator to an intermediate pressure (IP) steam turbine or an intermediate pressure steam turbine section, or any possible combination thereof.

[0005] In another embodiment, the system may include a plant comprising a gas turbine configured to output exhaust gas, a heat recovery steam generator (HRSG) configured to receive exhaust gas and output steam, and a steam turbine configured to receive steam. The system may also include a carbon capture system configured to capture undesirable gases from the exhaust gas in the separation material, and a controller configured to initiate partial load operation and / or shutdown operation of the plant. The controller may control the gas turbine to reduce to partial load conditions and continue to output exhaust gas, control a first set of valves to at least partially close to reduce or disable steam flow to the steam turbine, and control a second set of valves to enable or increase steam flow from the HRSG to the carbon capture system through a backup line for a certain period to perform a regeneration process for the separation material. As in the embodiment outlined above, the system may more specifically include a main extraction line configured to be fluidically coupled to or branched from the heat recovery steam generator and to provide steam from the heat recovery steam generator to the gas capture system. The backup line is also fluidly coupled to or branched from the heat recovery steam generator at at least one steam extraction location that provides a higher steam pressure than the steam extraction location to which the main extraction line is coupled to or branched from the heat recovery steam generator.For example, the main extraction line may branch off a line configured to supply steam to a low-pressure steam turbine or a low-pressure steam turbine section, while the backup line may branch off a line configured to supply high-pressure steam from a heat recovery steam generator to a high-pressure steam turbine or a high-pressure steam turbine section and / or a line configured to supply steam from a high-pressure steam turbine or a high-pressure steam turbine section to a heat recovery steam generator and / or a line configured to supply steam from a heat recovery steam generator to a medium-pressure steam turbine or a medium-pressure steam turbine section, or any possible combination thereof.

[0006] In another embodiment, the method may include the steps of initiating a shutdown operation or partial load operation of a plant having a gas turbine, a steam turbine, a heat recovery steam generator (HRSG), and a carbon capture system having a separation material; controlling the gas turbine to reduce it to a partial load condition; controlling a first set of valves to at least partially close the steam flow to the steam turbine to reduce or disable the steam flow to the steam turbine; and controlling a second set of valves coupled to a backup line to enable or increase the steam flow from the HRSG to the carbon capture system to perform a regeneration process for the separation material. Brief explanation of the drawing

[0007] These and other features, aspects, and advantages of the present invention will be better understood when reading the following detailed description with reference to the accompanying drawings, in which similar characters represent similar parts throughout the drawings. FIG. 1 is a block diagram of one embodiment of a combined cycle system having one or more gas capture systems. FIG. 2 is a schematic diagram of one embodiment of the combined cycle system of FIG. 1, further illustrating a gas turbine, a heat recovery steam generator (HRSG), a carbon capture system, and a steam turbine. FIG. 3 is a flowchart of an exemplary method for shutting down the complex cycle system of FIG. 1. FIG. 4 is a flowchart of an exemplary method for shutting down the complex cycle system of FIG. 1. Specific details for implementing the invention

[0008] One or more specific embodiments of the present invention will be described below. In order to provide a concise description of these embodiments, not all features of actual implementations may be described herein. It should be recognized that when developing any such actual implementation, as in any engineering or design project, numerous implementation-specific judgments, such as compliance with system-related and business-related constraints that may differ from implementation to implementation, must be made to achieve the developer's specific goals. Furthermore, it should be recognized that while such development efforts may be complex and time-consuming, they will nevertheless be routine work of design, fabrication, and manufacturing for those skilled in the art who have an interest in this disclosure.

[0009] When introducing the elements of various embodiments of the present invention, the articles (“a,” “an,” “the”) and “said” are intended to imply that there is one or more elements. The terms “comprising,” “comprising,” and “having” are intended to be inclusive and imply that there may be additional elements other than those listed.

[0010] The disclosed embodiments include systems and methods for improving the carbon capture rate of combustion systems, such as combustion-driven power plants and / or combined cycle power plants, having one or more gas capture systems. The gas capture systems are configured to remove undesirable gases (e.g., carbon dioxide (CO2)) from the exhaust gas of the combustion system. In the disclosed embodiments, the combustion system includes a backup line configured to provide heated water and / or steam from a heat recovery steam generator (HRSG) to the gas capture system during a shutdown operation of the combustion system. Thus, the gas capture system can perform a regeneration operation during the shutdown operation and increase the amount of available separation material for a subsequent combustion operation, which can improve the carbon capture rate during a subsequent startup operation.

[0011] FIG. 1 is a block diagram of one embodiment of a combined cycle system (10) having a gas turbine system (12), a steam turbine system (14), a heat recovery steam generator (HRSG) (16), a gas treatment system (18) having one or more gas capture systems (20), and a controller (22) coupled to each of the systems (12, 14, 16, and 18). As described below, one or more gas capture systems (20) of the gas treatment system (18) are configured to capture undesirable gases (e.g., CO2) from exhaust gases and / or air (e.g., direct air capture), wherein heat (e.g., steam) is used for a desorption mode during both normal operation and shutdown operation of the combined cycle system (10). In a given embodiment, during a shutdown operation, the combined cycle system (10) is configured to supply heat (e.g., steam) to a gas treatment system (18) (e.g., gas capture system (20)) until the separation material (e.g., adsorbent material of the adsorber and / or solvent of the stripper) is substantially free of undesirable gases (e.g., CO2) and the regeneration of the separation material is completed. For example, during a shutdown operation, the gas turbine system (12) may initiate a shutdown procedure to switch from full-load conditions to partial-load conditions, and the steam turbine system (14) may initiate a shutdown procedure to close the main valve to stop the supply of steam to the steam turbine and open the bypass valve to bypass the steam turbine, and the steam generated by the HRSG (16) is supplied to the gas treatment system (18) (e.g., gas capture system (20)) to complete the regeneration of the separation material. Upon completion of regeneration, the combined cycle system (10) can then continue and complete the shutdown procedure of the gas turbine system (12).In other words, during partial load conditions of the gas turbine system (12), the regeneration of the separated material is achieved using steam from the HRSG (16), thereby preparing the gas collection system (20) for subsequent start-up operations.

[0012] Before discussing the details of the gas treatment system (18), various aspects of the combined cycle system (10) are further discussed in detail. For the purpose of orientation in the drawings, references may be made to an axial direction or axis (40), a radial direction or axis (42) extending radially away from the axial direction or axis (40), and a circumferential direction or axis (44) extending circumferentially around the axial direction or axis (40). The directions or axes (40, 42, 44) may be related, for example, to the rotation axis (36) of the gas turbine system (12).

[0013] The gas turbine system (12) comprises an air intake (50), a compressor (52) having one or more compressor stages, one or more combustors (54), a turbine (56) having one or more turbine stages, and a load (58) (e.g., an electric generator) driven by the turbine (56). In a specific embodiment, the gas turbine system (12) further comprises an exhaust gas recirculation (EGR) system (60) configured to recirculate exhaust gas (62) to the air intake (50). The recirculated exhaust gas (62) contains certain emissions (e.g., nitrogen oxides (NO₂)) associated with combustion in the combustor (54). XIt helps to reduce the formation and temperature of )). When in operation, the compressor (52) takes air (also including exhaust gas (62) if the EGR system (60) is active) from the air intake (50) and compresses the air and / or exhaust gas (62) in one or more compressor stages (e.g., stages of rotary compressor blades). Then, the combustor (54) burns fuel from the fuel supply system together with the compressed air and / or exhaust gas to produce hot combustion gas. The hot combustion gas expands and drives one or more turbine stages (e.g., stages of rotary turbine blades) in the turbine (56) to drive the rotation of the compressor (52) and the load (58) through the shaft. The turbine (56) then outputs the hot combustion gas as exhaust gas (62).

[0014] The HRSG (16) recovers waste heat from exhaust gas (62) to generate steam for driving a steam turbine system (14). The HRSG (16) includes a high-pressure (HP) steam section (70), an intermediate-pressure (IP) steam section (72), and a low-pressure (LP) steam section (74), which are configured to generate HP steam (76), IP steam (78), and LP steam (80). The steam turbine system (14) may include an HP steam turbine (82) driven by HP steam (76), an IP steam turbine (84) driven by IP steam (78), and an LP steam turbine (86) driven by LP steam (80). In addition to the steam provided by the HRSG (16), the HP steam turbine (82) provides IP steam to the IP steam turbine (84), and the IP steam turbine (84) provides LP steam to the LP steam turbine (86). Then, the LP steam turbine (86) outputs any remaining steam / water to a condensate line (88) coupled to the LP steam section (74) of the HRSG (16). The condensate line (88) may include a condenser (90) configured to condense any remaining steam to form condensate, and a pump (92) configured to pump the condensate back to the LP steam section (74). In operation, the steam turbine system (14) drives a load (94) (e.g., an electric generator) through a shaft. In a given embodiment, the steam turbine system (14) and / or HRSG (16) may provide heated water and / or steam (e.g., HP steam (76), IP steam (78) and / or LP steam (80)) to the gas treatment system (18) to support a desorption mode (e.g., regeneration operation) of one or more gas capture systems (20). In another example, the gas collection system (20) may accommodate heated water and / or steam in a temperature range of 100 to 150 degrees Celsius, 110 to 150 degrees Celsius, 120 to 150 degrees Celsius, or 130 to 150 degrees Celsius.

[0015] After the HRSG (16), the exhaust gas (62) may flow to an EGR system (60) and / or a gas treatment system (18). In the illustrated embodiment, the exhaust gas (62) flows through one or more gas capture systems (20) configured to capture undesirable gases. The undesirable gases are carbon dioxide (CO₂). X )(e.g., carbon dioxide (CO2) and carbon monoxide (CO)), nitric oxide (NO₂) X )(e.g., nitrogen dioxide (NO2)), sulfur oxides (SO₄) X It may include )(e.g., sulfur dioxide (SO2)), or any combination thereof. In the following discussion, CO2 may be used as an example of an undesirable gas; however, the gas capture system (20) may be designed to capture any of the aforementioned undesirable gases. For example, the gas capture system (20) may include one or more carbon capture systems (100) (e.g., CO2 capture systems). The gas capture system (20) (e.g., carbon capture systems (100)) may include an adsorbent-based gas capture system, a solvent-based gas capture system, a cryogenic gas capture system, or any combination thereof, configured to remove and capture undesirable gases. A carbon capture system (100) may include components (102, 104, 106, 108) configured to output a treated gas (110) and a captured gas (112) (e.g., CO2) by enabling the capture of an undesirable gas (e.g., CO2) from an exhaust gas (62). The treated gas (110) may be substantially free of the undesirable gas (e.g., CO2) and may be discharged through an exhaust stack. The captured gas (112) (e.g., CO2) may be compressed by a compression system (114) and stored and / or transported by a storage and / or pipeline system (116).

[0016] In a specific embodiment, the carbon capture system (100) is an adsorbent-based carbon capture system, and the components (102, 104, 106 and / or 108) comprise a plurality of adsorbent-based carbon capture units (e.g., adsorbers). For example, the adsorbent-based carbon capture units may comprise a temperature swing adsorption (TSA) unit or an adsorber, wherein the temperature swing or change is used to operate sequentially in an adsorption mode, a desorption mode, and a cooling mode at different temperatures. In the adsorption mode, the adsorber is configured to adsorb an undesirable gas (e.g., CO2) onto the adsorbent material at a first temperature. In the desorption mode, the adsorber is configured to desorb the undesirable gas (e.g., CO2) from the adsorbent material by heating the adsorbent material from the first temperature to a higher second temperature using a heat source (e.g., regeneration of the adsorbent material). The heat source may include a heated fluid, such as a heated gas and / or liquid (e.g., steam). In the following discussion, the heat source includes steam from a steam turbine system (14) and / or HRSG (16) during normal operation and / or shutdown operation of the combined cycle plant (10). In particular, the combined cycle system (10) continues the steam supply to complete the regeneration of the adsorbent material during shutdown operation by generating steam from the HRSG (16) by maintaining a partial load condition of the gas turbine system (12) to support the regeneration of the adsorbent material of the carbon capture system (100), for example. In cooling mode, the adsorber is cooled to prepare for the next adsorption mode.

[0017] In a specific embodiment, the carbon capture system (100) is a solvent-based carbon capture system, and the components (102, 104, 106 and / or 108) include one or more absorbers, strippers, and associated equipment. For example, the absorber is configured to output the treated gas (110) through an exhaust stack and a CO2-rich solvent to the stripper by absorbing an undesirable gas (e.g., CO2) into the solvent. The stripper is configured to apply heat to the CO2-rich solvent, thereby stripping the undesirable gas (e.g., CO2) from the solvent to produce the captured gas (112) and the CO2-lean solvent (e.g., regeneration of the solvent). The stripper may receive heat through a heat source such as heated gas and / or liquid (e.g., steam). The stripper returns the CO2-lean solvent to the absorber to repeat the cycle. In the following discussion, the heat source includes steam from the steam turbine system (14) and / or HRSG (16) during normal operation and / or shutdown operation of the combined cycle plant (10). In particular, the combined cycle system (10) continues the steam supply to complete the regeneration of the solvent during shutdown operation by generating steam from the HRSG (16) by maintaining the partial load condition of the gas turbine system (12) to support the regeneration of the solvent of the carbon capture system (100), for example.

[0018] In the illustrated embodiment, the controller (22) is configured to control all aspects of the combined cycle system (10). The controller (22) includes one or more processors (120), a memory (122), instructions (124) stored in the memory (122) and executable by the processor (120), and a communication circuit (126) configured to communicate with the sensors and various equipment of the combined cycle system (10). For example, the controller (22) is configured to receive sensor feedback from sensors coupled to the gas turbine system (12), the steam turbine system (14), the HRSG (16), and the gas processing system (18) (e.g., the gas capture system (20)), and to control the same equipment based on the sensor feedback, operating mode, user input, computer model, or any combination thereof. The sensors may include temperature sensors, pressure sensors, flow sensors, gas composition sensors, or any combination thereof. In a specific embodiment, the controller (22) is configured to control the operation of the gas collection system (20) (e.g., carbon collection system (100)) by controlling, for example, an operation mode (e.g., adsorption mode, desorption mode, and cooling mode), controlling a heat source to supply a heated fluid (e.g., steam) to the gas collection system (20), controlling a cooling source to supply a cooled fluid to the gas collection system (20), or any combination thereof.

[0019] For example, the controller (22) may initiate a shutdown operation (e.g., a controlled shutdown operation) of the combined cycle system (10). During the shutdown operation, for example, the controller (22) may instruct the gas turbine system (12) to operate at a partial load (e.g., 30, 40, 50, or 60 percent of the full load) and to output exhaust gas (62). The controller (22) may instruct the shutdown of the steam turbine system (14) to isolate the HRSG (16). The controller (22) may instruct the HRSG (16) to generate steam (128) with exhaust gas (62) and instruct a set of valves (130) to open to provide steam (128) to the gas collection system (20) (e.g., carbon collection system (100)) to support the desorption mode or regeneration of the separation material (e.g., adsorbent material and / or solvent). The controller (22) may monitor the gas collection system (20) for the completion of the desorption mode. The controller (22) may determine the completion of the desorption mode based on the elapsed time of a certain period, a comparison between the concentration of undesirable gases in the separation material and a concentration range, or both. In response to completion, the controller (22) may direct a set of valves (130) to close, the HRSG (16) to stop producing steam (128), the gas turbine system (12) to complete deloading, or any combination thereof. In this way, the controller (22) can complete shutdown operations.

[0020] FIG. 2 is a schematic diagram of a gas treatment system (18) having a gas turbine system (12), a steam turbine system (14), an HRSG (16), one or more carbon capture systems (100), and a controller (22) coupled to each of the systems (12, 14, 16, and 18). In a given case, the carbon capture system (100) may be coupled to an auxiliary boiler (157) that provides additional steam to the carbon capture system (100). For example, the amount of steam supplied from the HRSG (16) may be less than the critical steam supply amount, and the auxiliary boiler (157) may provide additional steam to enable the regeneration process of the carbon capture system (100). In a given embodiment, the controller (22) is configured to control the steam supply from the HRSG (16) and auxiliary boiler (157) to the carbon capture system (100) to complete the regeneration process during partial load operation and / or shutdown operation of the combined cycle system (10). Accordingly, the controller (22) may selectively activate, deactivate, increase, decrease, or any combination thereof any number of steam supplies to the carbon capture system (100).

[0021] During the combustion operation, the gas turbine system (12) may be outputting exhaust gas (62), and gas capture systems (20) (e.g., carbon capture system (100)) may be performing an adsorption operation to enable the capture of undesirable gases (e.g., CO₂) from the exhaust gas (62). The exhaust gas (62) may also be supplied to the HRSG (16) for steam generation. The HRSG (16) may provide steam to drive the steam turbine system (14). For example, the HP steam section (70) of the HRSG (16) may supply HP steam (76) to the HP steam turbine (82) through the inlet of the HP steam turbine (82). The HP steam turbine (82) may supply HP return steam (150) through the outlet of the HP steam section (70), which directs the HP return steam (150) back to the HRSG (16). The IP steam section (72) of the HRSG (16) can supply IP steam (78) to the IP steam turbine (84) through the inlet of the IP steam turbine (84). The LP steam section (74) can receive steam from the LP steam section (74) of the HRSG (16) and the IP steam turbine (84) through the inlet of the LP steam turbine (86). Then, the LP steam turbine (86) outputs any remaining steam / water to a condensate line (88) coupled to the LP steam section (74) of the HRSG (16). The condensate line (88) may include a condenser (90) configured to condense any remaining steam to form condensate, and a pump (92) configured to pump the condensate back to the LP steam section (74). In a given case, the steam turbine system (14) may provide heated water and / or steam to the carbon capture system (100) to support a desorption mode (e.g., regeneration operation) of the carbon capture system (100). Although the following discussion focuses on the carbon capture system (100), the illustrated embodiments are applicable to any type of gas capture system (20).For example, as illustrated, the LP steam turbine (86) can supply steam to the carbon capture system (100) through the main extraction line (152).

[0022] To facilitate steam movement between the HRSG (16), the steam turbine system (14), and the carbon capture system (100), the controller (22) may adjust the position of one or more valves (e.g., actuator-driven valves) within the combined cycle system (10). For example, the controller (22) may instruct a first set of valves (154) positioned between the HRSG (16) and the steam turbine system (14) to open to provide HP steam (76), IP steam (78), and / or LP steam (80) to the steam turbine system (14). In another example, the controller (22) may instruct a second set of valves (156) to open to provide LP steam (80) to the carbon capture system (100). The controller (22) may instruct the first set of valves (154) to close when instructing the second set of valves (156) to open, thereby supplying LP steam (80) to the main extraction line (152). In another example, the controller (22) may instruct the third valve (158) coupled to the LP steam turbine (86) to adjust its position based on the direction of the steam. For example, the controller (22) may instruct the third valve (158) to open in a first direction to supply LP steam (80) or steam from the IP steam turbine (84) to the LP steam turbine (86), and instruct it to open in a second direction to supply steam from the LP steam turbine (86) to the carbon capture system (100) through the main extraction line (152).

[0023] After a certain period, the controller (22) may initiate a controlled shutdown of the combined cycle system (10). The controlled shutdown may initiate a reduction in the load of the gas turbine system (12) from a first load condition (e.g., a larger load condition or a full load condition) to a second load condition (e.g., a smaller load condition or a partial load condition), and also a shutdown of steam through the steam turbines (e.g., HP steam turbine (82), IP steam turbine (84), and LP steam turbine (86)) by closing the main valves and opening the bypass valves. For example, the controller (22) may shut down the steam turbine system (14) by isolating the steam turbine system (14) from the HRSG (16) by directing the closure of the first set of valves (154), the second set of valves (156), and the third valve (158). When the valves reach a minimum position (e.g., a closed position), the steam turbine system (14) may trip and begin deceleration. In other cases, the controller (22) may instruct the steam turbine system (14) to decelerate based on instructing the valves to close.

[0024] During a controlled shutdown of the combined cycle system (10), the controller (22) may instruct the gas turbine system (12) to operate at a reduced load (e.g., partial load conditions) for an extended period, thereby causing the HRSG (16) to generate steam (128) for the regeneration operation of the carbon capture system (100). In other words, instead of immediately continuing the shutdown of the gas turbine system (12), the gas turbine system (12) will continue to operate at a reduced load to continue generating steam in the HRSG (16) to support the regeneration operation. For example, during a controlled shutdown, the controller (22) may instruct the gas turbine system (12) to change from a full load condition (e.g., 100 percent power output) to a partial load condition (e.g., 30, 40, 50, or 60 percent or less power output) so that exhaust gas (62) continues to be sent to the HRSG (16) to generate steam (128). For example, during a regeneration operation, the controller (22) may instruct the gas turbine system (12) to maintain a partial load condition at a constant load and / or a gradually decreasing load, so that the HRSG (16) can still generate enough steam (128) for the regeneration operation. In another example, the controller (22) may instruct the gas turbine system (12) to maintain a minimum environmental load (MECL) so that the HRSG (16) generates steam (128). The steam (128) may be residual steam generated while the gas turbine system (12) is operating under a partial load condition.

[0025] During the shutdown operation, steam generated by the HRSG (16) can be supplied to the carbon capture system (100) via the backup line (160). For example, the backup line (160) may be located between the HRSG (16) and the steam turbine system (14). As illustrated, the inlet of the backup line (160) may be located between the HRSG (16) and the HP steam turbine (82), and the outlet of the backup line (160) may be located along the main extraction line (152). The backup line (160) may include another inlet located between the HRSG (16) and the IP steam turbine (84). To provide steam (128), the controller (22) may instruct the fourth set of valves (161) on the backup line (160) to open. In this way, steam (128) output by the HRSG (16) (e.g., HP steam (76), IP steam (78)) can be captured by the backup line (160) and supplied to the carbon capture system (100).

[0026] The steam (128) may include high-temperature reheat steam and low-temperature reheat steam. The high-temperature reheat steam may include steam (128) traversing from the outlet of the IP steam turbine (84) along the backup line (160) to the carbon capture plant (100). The low-temperature reheat steam may include steam supplied from the outlet of the HP steam return section (150) along the additional backup line (167) to the backup line (160) and the carbon capture plant (100). The high-temperature reheat steam may have a higher temperature compared to the low-temperature reheat steam.

[0027] The backup line (160) may include a fifth valve (162) that can be opened or closed based on the operation of the combined cycle system (10). For example, the controller (22) may instruct the fifth valve (162) to open during a shutdown operation to provide steam along the backup line (160), and to close during a combustion operation.

[0028] The backup line (160) may also include a first attemperator (164) configured to reduce or control the temperature of the steam (128). For example, the steam may travel along the backup line (160) in a temperature range of 300 to 500 degrees Celsius. To maintain the temperature of the steam (128) within a constant temperature range, the first attemperator (164) along the backup line (160) receives water from an attemperator water source (166) to adjust the temperature of the steam (128). For example, the attemperator water source (166) may adjust the temperature of the steam (128) based on a temperature control setpoint that can be determined based on a regeneration process. The superheat reduction water supply source (166) can inject water into the superheat reducer (164) along the backup line (160) to reduce the temperature of the steam (128) when the temperature of the steam (128) is higher than the temperature control set point.

[0029] The controller (22) can control the operation of the superheat reduction water supply source (166) based on a certain temperature range. For example, the controller (22) can monitor the temperature of the steam (128) through one or more temperature sensors and instruct the sixth set of valves (168) to open or close based on a comparison between this temperature and the first temperature range. If the temperature of the steam (128) is outside the first temperature range, the controller (22) can adjust the temperature of the steam (128) by instructing the sixth set of valves (168) to open to provide water from the superheat reduction water supply source (166) to the first superheat reducer (164). If the temperature of the steam (128) is within the first temperature range, the controller (22) can instruct the sixth set of valves (168) to close or keep them closed. If the steam (128) exceeds an upper safety threshold (e.g., maximum steam pressure and / or maximum steam temperature), the controller (22) may release the steam pressure by instructing the safety valve (170) to open along the backup line (160) for safety reasons. The safety valve (170) may include a pressure release valve.

[0030] The main extraction line (152) may include a second superheat reducer (174) configured to reduce or control the temperature of the steam (128) along the main extraction line (152). For example, the steam (128) may travel along the backup line (160) in a temperature range of 200 to 300 degrees Celsius. The controller (22) may monitor the temperature through one or more sensors and compare the temperature of the steam (128) along the main extraction line (152) with the second temperature range. If the temperature of the steam (128) falls outside the second temperature range, the controller (22) may adjust the temperature of the steam (128) by instructing the seventh set of valves (172) to open to inject water into the second superheat reducer (174) along the main extraction line (152). If the temperature of the steam (128) is within the second temperature range, the controller (22) may instruct the valves of the seventh set to close or remain closed. From the main extraction line (152), steam (128) may be supplied to the carbon capture system (100) for regeneration operation.

[0031] The carbon capture system (100) may perform a regeneration operation using steam (128). The regeneration operation may include desorbing undesirable gases from the separation material by heating the separation material (e.g., the adsorbent material of the adsorber, the solvent of the stripper). For example, the carbon capture system (100) may remove undesirable gases from the adsorbent material by heating the adsorbent material from a first temperature to a second temperature higher than the first temperature using steam (128). In another example, the carbon capture system (100) may provide a CO2-lean solvent by applying heat to a CO2-rich solvent to strip undesirable gases from the solvent. The HRSG (16) may provide steam (128) to the carbon capture system (100) for any suitable period during a shutdown operation, for example, while the gas turbine system (12) is operating under partial load conditions and the steam turbine system (14) remains in a shutdown state. The controller (22) can monitor the completion of the regeneration operation. For example, the controller (22) can monitor the concentration of undesirable gases in the separated material, the time taken to perform the regeneration operation, etc. In response to determining the completion of the regeneration operation, the controller (22) can continue the shutdown operation until it is completed. For example, the controller (22) can stop the supply of steam (128) to the carbon capture system (100) by instructing the fourth set of valves (161), the fifth valve (162), or both to be closed. In another example, the controller (22) can instruct the gas turbine system (12) to continue deloading and eventually shut down completely. In this way, the controller (22) can complete the shutdown of the combined cycle system (10). By providing steam (128) during the shutdown operation, the regeneration of the separated material can be completed, making it possible for the subsequent startup operation to start the carbon capture operation more quickly and efficiently.In this way, the carbon capture rate of the composite cycle system (10) can be increased during subsequent startup operations.

[0032] As discussed in this specification, valves may include any suitable valves for providing heated water and / or steam between the steam turbine system (14), HRSG (16), and carbon capture system (100). For example, valves may include check valves, two-way valves, ball valves, gate valves, butterfly valves, etc. Each valve may be coupled to an actuator (e.g., electric actuator, pneumatic actuator, and / or hydraulic actuator) that controls the position of the valve. For example, the actuator may adjust the position of the valve between an open position and a closed position based on instructions from the controller (22).

[0033] FIG. 3 is a flowchart of one embodiment of a process (200) for shutting down the combined cycle system (10) of FIG. 1 and 2. In the illustrated embodiment, the process (200) may be partially or wholly controlled by the controller (22) of FIG. 1 and 2. The process (200) includes initiating a controlled shutdown of the plant (10) having a gas turbine system (12), a steam turbine system (14), a heat recovery steam generator (HRSG) (16), and a carbon capture system (100) (block (202)). The process (200) also controls valves to direct steam from the HRSG (16) to the carbon capture system (100) for regeneration during the controlled shutdown (block (204)). For example, the controller (22) can isolate the steam turbine system (14) from the HRSG (16) by instructing the first set of valves (154), the second set of valves (156), and the third valve (158) to close. The controller (22) can also provide steam (128) to the carbon capture system (100) by instructing the fourth set of valves (161) and the fifth valve (162) to open. Subsequently, the process (200) completes the controlled shutdown of the plant (10) after the regeneration of the carbon capture system (100) is complete (block (206)). For example, the controller (22) may instruct the fourth set of valves (161) and the fifth valve (162) to close to stop supplying steam (128) to the carbon capture system (100), or to continue deloading the gas turbine system (12), or to shut down completely, or both. In this way, the controller (22) can complete the controlled shutdown of the composite cycle system (10) after the complete regeneration of the separated material within the carbon capture system (100).

[0034] FIG. 4 is a flowchart of one embodiment of a process (240) for shutting down the combined cycle system (10) of FIG. 1 and FIG. 2. In the illustrated embodiment, the process (240) may be partially or wholly controlled by the controller (22) of FIG. 1 and FIG. 2. The process (240) includes initiating a controlled shutdown of the plant (10) having a gas turbine system (12), a steam turbine system (14), a heat recovery steam generator (HRSG) (16), and a carbon capture system (100) (block (242)). The process (240) also controls the gas turbine system (12) to reduce it to a partial load condition (block (244)). In a given case, the gas turbine system (12) may operate under full load conditions. In other cases, the gas turbine system (12) may operate under a partial load condition lower than the full load condition, for example, 30, 40, 50, or 60 percent or less of the full load condition. Next, process (240) initiates the shutdown of the steam turbine system (14) by controlling the valves of the steam turbine system (14) to close (block (246)). For example, the controller (22) can isolate the steam turbine system (14) from the HRSG (16) by instructing the first set of valves (154) to close. Process (240) can also shut down the steam turbine system (14) after closing the valves (block (248)). Process (240) can supply steam to the carbon capture system (100) by controlling the valves to direct steam from the HRSG (16) (block (250)). For example, the controller (22) can direct steam (128) from the HRSG (16) to the carbon capture system (100) through the backup line (160) by instructing the valves to open. Process (240) also controls the carbon capture system (100) to regenerate using steam (128) from the HRSG (16) (block (252)).For example, the controller (22) can instruct the carbon capture system (100) to operate in a desorption mode using steam (128) (e.g., to perform a regeneration operation). The process (240) can monitor the carbon capture system (100) for the completion of regeneration (block (254)). For example, the controller (22) can determine completion based on the elapsed time of a certain period, the concentration of undesirable gases in the separation material, or both. Subsequently, the process (240) can control the valves to stop (e.g., close) the steam (128) from the HRSG (16) to the carbon capture system (100) when regeneration is complete (block (256)). For example, the controller (22) can instruct the valves to close to stop directing steam from the HRSG (16) to the carbon capture system (100). Process (240) can also control the gas turbine system (12) to continue deloading to complete the controlled shutdown of the plant (block (258)).

[0035] The technical effect of the disclosed embodiments is to provide steam during a shutdown process to improve gas capture by an adsorbent-based gas capture (e.g., carbon capture of CO2) system or a solvent-based gas capture system. During the shutdown process, for example, the gas turbine may operate at load (e.g., partial load) and output exhaust gas, thereby allowing the HRSG to continue outputting steam. Steam may be supplied to the gas capture system via a backup line for a regeneration process. For example, steam may remove undesirable gases (e.g., CO2) from a CO2-rich solvent and increase the total CO2 captured by the gas capture system before a complete shutdown. In another example, steam may desorb undesirable gases (e.g., CO2) from the adsorbent material, thereby regenerating the adsorbent material. Supplying steam to the gas capture system may increase the amount of CO2-lean solvent and / or CO2-lean adsorbent material for carbon capture during a subsequent startup operation. As such, the disclosed embodiments may provide an increased CO2 capture rate during the subsequent startup process due to a more dilute solvent and / or an increased amount of available adsorbent material.

[0036] The subject described in detail above may be defined by one or more provisions as stated below.

[0037] The system comprises a gas capture system including a separation material—the gas capture plant is configured to operate a regeneration process during partial load operation and / or shutdown operation to desorb undesirable gases from the separation material and lean the separation material for an absorption process—a heat recovery steam generator (HRSG) configured to receive exhaust gas and generate steam, and a backup line fluidically coupling the gas capture system to the HRSG—the backup line is configured to provide steam from the HRSG to the gas capture system for the regeneration process during partial load operation and / or shutdown operation.

[0038] In a system as described in the preceding provision and / or any appended claim or in connection therewith, the system comprises a main extraction line fluidically coupled to or branched from a heat recovery steam generator and configured to provide steam from the heat recovery steam generator to a gas collection system, and a backup line is also fluidly coupled to or branched from the heat recovery steam generator at at least one steam extraction location that provides a higher steam pressure than the steam extraction location to which the main extraction line is coupled to or branched from the heat recovery steam generator. For example, the main extraction line may branch to a line configured to supply steam to a low-pressure steam turbine or a low-pressure steam turbine section, while the backup line may branch to a line configured to supply high-pressure steam from the heat recovery steam generator to a high-pressure steam turbine or a high-pressure steam turbine section and / or a line configured to supply steam from the high-pressure steam turbine or a high-pressure steam turbine section to the heat recovery steam generator and / or a line configured to supply steam from the heat recovery steam generator to a medium-pressure steam turbine or a medium-pressure steam turbine section, or any possible combination thereof.

[0039] In a system as described in any preceding provision and / or any appended claim or in connection therewith, a gas turbine system configured to output exhaust gas during partial load operation and / or shutdown operation.

[0040] In a system as described in any prior provision and / or any appended claim or in connection therewith, the superheat reducer coupled to a backup line—the superheat reducer is configured to control the temperature of steam along the backup line—a pressure reducing valve for controlling the pressure of steam for a regeneration process, and a safety valve coupled to a backup line—the safety valve is configured to release steam when the steam pressure exceeds a pressure threshold.

[0041] In a system as described in any prior provision and / or any appended claim or in connection therewith, the system includes a superheat reduction water supply configured to inject water into a superheat reducer along a backup line based on the steam temperature being higher than the temperature control setpoint for the regeneration process.

[0042] In a system as described in any prior provision and / or any appended claim or in connection therewith, the backup line is configured to provide steam to a main extraction line fluidically coupled to a gas capture system.

[0043] In a system as described in any prior provision and / or any appended claim or in connection therewith, the main extraction line includes a superheat reducer configured to control the temperature of steam along the main extraction line.

[0044] In a system as described in any prior provision and / or any appended claim or in connection therewith, the system includes a superheat reduction water source configured to inject water into a superheat reducer along a main extraction line based on the steam temperature being higher than a temperature control setpoint for a regeneration process.

[0045] In a system as described in any prior provision and / or any appended claim or in connection therewith, a steam turbine fluidly coupled to an HRSG through a set of valves, and a controller communically coupled to a set of valves—the controller is configured to control each of the set of valves to close at least partially upon receiving a command to initiate a partial load operation and / or a shutdown operation.

[0046] In a system as described in any preceding provision and / or any appended claim or in connection therewith, a controller is configured to monitor the regeneration process of the gas capture system and steam from the HRSG, and to start a steam supply from an additional steam source to support the regeneration process of the gas capture system based on the fact that the amount of steam from the HRSG is less than a critical steam supply amount.

[0047] In a system as described in any preceding provision and / or any appended claim or in connection therewith, an additional steam source comprises an auxiliary boiler.

[0048] The system may include a plant comprising a gas turbine configured to output exhaust gas, a heat recovery steam generator (HRSG) configured to receive exhaust gas and output steam, and a steam turbine configured to receive steam. The system may also include a carbon capture system configured to capture undesirable gases from the exhaust gas in the separation material, and a controller configured to initiate partial load operation and / or shutdown operation of the plant. The controller may control the gas turbine to reduce to partial load conditions and continue to output exhaust gas, control a first set of valves to at least partially close to reduce or disable steam flow to the steam turbine, and control a second set of valves to enable or increase steam flow from the HRSG to the carbon capture system through a backup line for a certain period to perform a regeneration process for the separation material. More specifically, the system may include a main extraction line fluidically coupled to or branched from the heat recovery steam generator and configured to provide steam from the heat recovery steam generator to the gas capture system. The backup line is also fluidly coupled to or branched from the heat recovery steam generator at at least one steam extraction location that provides a higher steam pressure than the steam extraction location to which the main extraction line is coupled to or branched from the heat recovery steam generator.For example, the main extraction line may branch off a line configured to supply steam to a low-pressure steam turbine or a low-pressure steam turbine section, while the backup line may branch off a line configured to supply high-pressure steam from a heat recovery steam generator to a high-pressure steam turbine or a high-pressure steam turbine section and / or a line configured to supply steam from a high-pressure steam turbine or a high-pressure steam turbine section to a heat recovery steam generator and / or a line configured to supply steam from a heat recovery steam generator to a medium-pressure steam turbine or a medium-pressure steam turbine section, or any possible combination thereof.

[0049] In a system as described in any prior provision and / or any appended claim or in connection therewith, the controller is configured to control the carbon capture system to perform a regeneration process using steam from the HRSG.

[0050] In a system as described in any preceding provision and / or any appended claim or in connection therewith, the controller is configured to stop steam from the HRSG to the carbon capture system by controlling a second set of valves to close based on the completion of the regeneration process or based on a change from the HRSG to an additional steam source for the completion of the regeneration process.

[0051] In a system as described in any preceding provision and / or any appended claim or in connection therewith, the controller is configured to control an additional steam source to start steam supply to support the regeneration process of the gas capture system based on the fact that the steam supply from the HRSG is less than the critical steam supply.

[0052] In a system as described in any prior provision and / or any appended claim or in connection therewith, the system comprises a superheat reducer configured to inject water into a superheat reducer along a backup line based on the fact that the temperature of the steam along the backup line is higher than the temperature control setpoint for the regeneration process.

[0053] In a system as described in any prior provision and / or any appended claim or in connection therewith, the controller is configured to control a second set of valves during the regeneration process to direct steam from the high-pressure steam (HP) section of the HRSG, the medium-pressure (IP) steam section of the HRSG, or a combination thereof, to a carbon capture system.

[0054] In a system as described in any prior provision and / or any appended claim or in connection therewith, the separation material comprises an adsorbent material or a solvent.

[0055] The method may include the steps of initiating a shutdown operation or partial load operation of a plant having a gas turbine, a steam turbine, a heat recovery steam generator (HRSG), and a carbon capture system having a separation material; controlling the gas turbine to reduce it to a partial load condition; controlling a first set of valves to at least partially close the steam flow to the steam turbine to reduce or disable the steam flow to the steam turbine; and controlling a second set of valves coupled to a backup line to enable or increase the steam flow from the HRSG to the carbon capture system to perform a regeneration process for the separation material.

[0056] In a method as described in any prior provision and / or any appended claim or in connection therewith, the method further comprises the steps of monitoring a carbon capture system during a regeneration process, controlling a second set of valves to stop directing steam to the carbon capture system based on the detection that the carbon capture system has completed the regeneration process, and controlling a gas turbine to continue deloading to complete the shutdown operation of the plant.

[0057] In a method as described in any preceding provision and / or any appended claim or in connection therewith, the method further comprises the step of controlling the steam supply of steam from an additional steam source to support the regeneration process of a carbon capture system based on the fact that the steam supply amount of steam from the HRSG is less than a critical steam supply amount.

[0058] The description provided discloses the present invention, including an optimal method, and uses examples that enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system and performing any included method. The scope of the present invention as claimed herein is limited by the appended claims and may include other examples other than those provided in the description provided above that come to mind for a person skilled in the art.

Claims

Claim 1 A system comprising: a gas collection system (20) including a separation material - said gas collection system is configured to collect undesirable gases from exhaust gases from the separation material and to regenerate the separation material for an absorption process by operating a regeneration process to desorb undesirable gases from the separation material -; a heat recovery steam generator (16) configured to receive the exhaust gas and generate steam; and a backup line (160) fluidically coupling the gas collection system (20) to the heat recovery steam generator (16) - said backup line is configured to provide steam from the heat recovery steam generator to the gas collection system for the regeneration process during partial load operation and / or shutdown operation - a system. Claim 2 A system according to claim 1, wherein the backup line (160) is fluidically coupled to the high-pressure steam section (70) of the heat recovery steam generator, the medium-pressure steam section (72) of the heat recovery steam generator, or a combination thereof, and is configured to provide steam from the heat recovery steam generator to the gas collection system for the regeneration process from the high-pressure steam section of the heat recovery steam generator, the medium-pressure steam section of the heat recovery steam generator, or a combination thereof. Claim 3 A system according to claim 1 or 2, comprising: an attemperator (164) coupled to the backup line—the attemperator is configured to control the temperature of steam flowing along the backup line—; a pressure reducing valve (162) for controlling the pressure of the steam supplied from the backup line to the gas collection system; and a safety valve (170) coupled to the backup line—the safety valve is configured to release steam when the steam pressure of the steam supplied from the backup line to the gas collection system exceeds a pressure threshold. Claim 4 A system according to any one of claims 1 to 3, wherein the backup line is configured to provide the steam to the main extraction line (152) fluidically coupled to the gas collection system. Claim 5 In paragraph 4, the system comprises a main extraction line including a superheat reducer (174) configured to control the temperature of the steam flowing along the main extraction line. Claim 6 A system further comprising: a gas turbine (12) configured to output the exhaust gas in any one of claims 1 to 5; a steam turbine (14) fluidically coupled to the heat recovery steam generator (16) and configured to receive steam from the heat recovery steam generator; and a controller (22) configured to initiate a partial load operation and / or a shutdown operation of the plant including the gas turbine, the steam turbine, the heat recovery steam generator and the gas collection system by: controlling the gas turbine to reduce to a partial load condition and continue to output the exhaust gas (244); and at least one of activating or increasing the steam flow from the heat recovery steam generator to the gas collection system through the backup line for a certain period of time to perform a regeneration process on the separated material. Claim 7 A system according to claim 6, wherein the controller is configured to perform at least one of reducing or deactivating the steam flow from the heat recovery steam generator to the steam turbine. Claim 8 A system configured to perform at least one of the following: in claim 6 or 7, the controller controls a first set of valves to at least partially close (246) to reduce or deactivate the steam flow to the steam turbine and / or controls a second set of valves coupled to the backup line to enable or increase the steam flow from the heat recovery steam generator to the gas collection system through the backup line (250). Claim 9 A system configured such that, in any one of claims 6 to 8, the controller controls the gas collection system to perform the regeneration process using steam from the heat recovery steam generator (252), monitors the regeneration process of the gas collection system over a period of time (254), and stops the steam flow from the heat recovery steam generator to the gas collection system based on the completion of the regeneration process or based on a change from the heat recovery steam generator to an additional steam source for the completion of the regeneration process (256). Claim 10 A method comprising: initiating a shutdown operation or partial load operation of a plant having a gas turbine (12), a steam turbine (14), a heat recovery steam generator (16), and a gas collection system (20) having a separation material (242); controlling the gas turbine to reduce to a partial load condition (244); and activating or increasing steam flow from the heat recovery steam generator to the gas collection system through a backup line to perform a regeneration process for the separation material. Claim 11 A method according to claim 10, comprising at least one of the steps of reducing or deactivating steam flow from the heat recovery steam generator to the steam turbine. Claim 12 A method comprising at least one of the steps of: controlling a first set of valves to at least partially close to reduce or deactivate the steam flow to the steam turbine (246) and / or controlling a second set of valves coupled to the backup line to enable or increase the steam flow from the heat recovery steam generator to the gas collection system through the backup line (250). Claim 13 A method according to any one of claims 10 to 12, further comprising: a step (254) of monitoring the gas collection system during the regeneration process; a step (256) of stopping directing steam to the gas collection system based on the detection of the gas collection system that completes the regeneration process; and a step (258) of controlling the gas turbine to continue deloading to complete the shutdown operation of the plant, wherein, in particular, the step of stopping directing steam to the gas collection system comprises a step of controlling a second set of valves. Claim 14 A method according to any one of claims 10 to 13, further comprising the step of controlling the steam supply amount of steam from an additional steam source to support the regeneration process of the gas capture system based on the fact that the steam supply amount of steam from the heat recovery steam generator is less than the critical steam supply amount. Claim 15 A system further comprising a controller (22) configured to perform the method of any one of claims 10 to 14 in any one of claims 1 to 9.

Images