Power plant and method of operation

At least one main air compressor makes a compressed ambient gas flow. The compressed ambient gas flow is delivered to both master and slave turbine combustors at a pressure that is greater than or substantially equal to an output pressure delivered to each turbine combustor from each turbine compressor as at least a first portion of a recirculated gas flow. A fuel stream is delivered to each turbine combustor, and combustible mixtures are formed and burned, forming the recirculated gas flows. A master and slave turbine power are produced, and each is substantially equal to at least a power required to rotate each turbine compressor. At least a portion of the recirculated gas flow is recirculated through recirculation loops. At least a second portion of the recirculated gas flow bypasses the combustors or an excess portion of each recirculated gas flow is vented or both.

BACKGROUND OF THE INVENTION

The subject matter of the present disclosure relates generally to the field of electric power plants, and more particularly to methods of operating stoichiometric exhaust gas recirculation turbine systems. Various types of gas turbine systems are known and in use for electricity generation in power plants. Typically, the gas turbine systems include a turbine compressor for compressing an air flow and a turbine combustor that combines the compressed air with a fuel and ignites the mixture to generate an exhaust gas. The exhaust gas may then be expanded through a turbine, thereby causing the turbine to rotate, which in turn may be connected to a turbine generator via a turbine shaft, for power generation. Gas turbines have traditionally used excess air within the combustion process to control turbine temperatures and manage undesirable emissions. This often results in an exhaust stream with large amounts of excess oxygen.

Accordingly, there exists a need for a power plant arrangement that uses a gas turbine system that may operate without an exhaust stream with large amounts of excess oxygen. Furthermore, it would be desirable for the power plant arrangement to provide for the option to further reduce emissions through treatment of exhaust gases and/or to recover streams of carbon dioxide, nitrogen, and water.

BRIEF DESCRIPTION OF THE INVENTION

In one aspect, a method for operating a power plant at constant speed no load is provided. Ambient air is compressed with at least one main air compressor to make a compressed ambient gas flow. At least a first portion of the compressed ambient gas flow having a first compressed ambient gas flow rate is delivered from the at least one main air compressor to a master turbine combustor at a pressure that is greater than or substantially equal to an output pressure delivered to the master turbine combustor from a master turbine compressor as at least a first portion of a master recirculated gas flow having a master recirculated gas flow rate. At least a second portion of the of the compressed ambient gas flow having a second compressed ambient gas flow rate is delivered from the at least one main air compressor to at least one slave turbine combustor at a pressure that is greater than or substantially equal to an output pressure delivered to the at least one slave turbine combustor from the at least one slave turbine compressor as at least a first portion of a slave recirculated gas flow having at least one slave recirculated gas flow rate. A master fuel stream is delivered to the master turbine combustor with a master fuel flow rate, wherein the master fuel flow rate, the first compressed ambient gas flow rate, and the master recirculated gas flow rate are sufficient to maintain combustion. At least one slave fuel stream is delivered to the at least one slave turbine combustor with at least one slave fuel flow rate, wherein the at least one slave fuel flow rate, the second compressed ambient gas flow rate, and the slave recirculated gas flow rate are sufficient to maintain combustion. At least a first portion of the compressed ambient gas flow is mixed with the at least a first portion of a master recirculated gas flow and with the master fuel stream in the master turbine combustor to form a master combustible mixture. At least a second portion of the compressed ambient gas flow is mixed with the at least a first portion of the at least one slave recirculated gas flow and with the at least one slave fuel stream in the at least one slave turbine combustor to form at least one slave combustible mixture. The master combustible mixture in the master turbine is burned to form the master recirculated gas flow. The at least one slave combustible mixture in the at least one slave turbine is burned to form the at least one slave recirculated gas flow. A master turbine connected to the master turbine compressor is driven using the master recirculated gas flow, such that the master turbine and a master turbine compressor rotate, and produce a master turbine power that is substantially equal to at least a power required to rotate the master turbine compressor. At least one slave turbine connected to the at least one slave turbine compressor is driven using the at least one slave recirculated gas flow, such that the at least one slave turbine and at least one slave turbine compressor rotate, and produce at least one slave turbine power that is substantially equal to a power required to rotate the at least one slave turbine compressor. At least a portion of the master recirculated gas flow is recirculated through a master recirculation loop, wherein the at least a portion of the master recirculated gas flow is recirculated from the master turbine to the master turbine compressor. At least a portion of the at least one slave recirculated gas flow is recirculated through at least one slave recirculation loop, wherein the at least a portion of the at least one slave recirculated gas flow is recirculated from the at least one slave turbine to the at least one slave turbine compressor. The master turbine combustor is bypassed with at least a second portion of the master recirculated gas flow as a master bypass flow having a master bypass flow rate and the master bypass flow rate is adjusted or an excess portion of the master recirculated gas flow is vented between an output of the master turbine compressor and an input to the master turbine compressor. The at least one slave turbine combustor is bypassed with at least a second portion of the at least one slave recirculated gas flow as at least one slave bypass flow having at least one slave bypass flow rate and the at least one slave bypass flow rate is adjusted or an excess portion of the at least one slave recirculated gas flow is vented between an output of the at least one slave turbine compressor and an input to the at least one slave turbine compressor or both.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, numerous specific details are given to provide a thorough understanding of embodiments. The embodiments can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the embodiments.

Reference throughout this specification to “one embodiment,” “an embodiment,” or “embodiments” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

Recent requirements in the power generation industry have necessitated the development of a gas turbine arrangement that may be configured to consume substantially all of the oxygen in the air working fluid to produce an essentially oxygen-free exhaust stream. Such an exhaust stream may be more easily suited to emissions reductions using NOxcatalysts. Additionally, such an exhaust stream may be better suited to post combustion carbon capture solutions due to the low oxygen concentrations. Furthermore, a largely oxygen-free exhaust stream may be more easily suited to enhanced oil recovery applications.

A substantially oxygen-free exhaust from a gas turbine may be accomplished by stoichiometric burning in the combustion system. That is, the oxygen-containing fresh air supply may be matched to the fuel flow such that the combustion process operates at near combustion stoichiometry.

A stoichiometric combustion reaction of methane and oxygen is illustrated below:
CH4+2O2→CO2+2H2O

Stoichiometric combustion may result in gas temperatures much too high for the materials and cooling technology employed in gas turbine engines. In order to reduce those high temperatures, a portion of the gas turbine exhaust products may be recirculated back to the combustion system to dilute the combustion temperatures. Ideally, this diluent gas should also be significantly oxygen free so as to not introduce additional oxygen into the system and thereby reduce the advantages of stoichiometric combustion. The gas turbine application using stoichiometric combustion and recirculated exhaust gas is referred to as Stoichiometric Exhaust Gas Recirculation (SEGR).

The SEGR system may use a supply of high pressure air fed directly into the combustion process to provide the oxygen for combustion. This air may be supplied by an auxiliary compressor. In practice, the ability of an auxiliary compressor to provide air at the pressure and flow rate required by the SEGR gas turbine will not be matched across all operating ranges of load and ambient temperature experienced by the system. The auxiliary compressor may allow the compressor to provide more air at times than is required by the gas turbine. Further, the auxiliary compressor may be designed with the capability to always provide more air than is required by the gas turbine. It some situations, it may be necessary to discharge some of the air compressed by the auxiliary compressor to the atmosphere.

As discussed in detail below, embodiments of the present invention may function to minimize emissions in gas turbine power plant systems by using an SEGR cycle that may enable substantially stoichiometric combustion reactions for power production. The SEGR gas turbine may be configured so as to provide a low oxygen content exhaust. This low oxygen content exhaust may be used with an NOxreduction catalyst to provide an exhaust stream that may also be free of NOxcontaminants.

Embodiments of the present invention include the ability to start up a gas turbine power plant that may use an SEGR cycle by first bringing the one or more gas turbines of the power plant up to constant speed no load operation. As used herein, the term “constant speed no load” means operating a gas turbine at a constant rotational speed (e.g., >1000 rpm) and producing enough power to operate at least the turbine compressor without any applied electrical load from an attached generator unit. In some embodiments, a gas turbine operating at constant speed no load may have a turbine that is running at full speed but that may not be connected to a power grid.

Power Plant Arrangement

Turning now to the drawings and referring first toFIG. 1an exemplary power plant arrangement10is illustrated. The exemplary power plant arrangement10may include a main air compressor12for compressing ambient air into at least a first portion of a compressed ambient gas flow26. In some embodiments, the at least a first portion of the compressed ambient gas flow26may be vented to the atmosphere via a master variable bleed valve14. Further, the power plant arrangement10may include a master turbine combustor32that may be fluidly connected to the main air compressor12. The flow of the at least a first portion of the compressed ambient gas flow26to the master turbine combustor32may be regulated by a master air injection valve25.

The master turbine combustor32may be configured to receive the at least a first portion of the compressed ambient gas flow26from the main air compressor12, a master recirculated gas flow50from a master turbine compressor30, and a master fuel stream28, to form a master combustible mixture and to burn the master combustible mixture to generate the master recirculated gas flow50. In some embodiments, the master fuel stream28may be regulated by a master gas control valve27to deliver a master fuel flow rate. In addition, the exemplary power plant arrangement10may include a master turbine34located downstream of the master turbine combustor32. The master turbine34may be configured to expand the master recirculated gas flow50and may drive an external load such as a master turbine generator20via a master turbine shaft22to generate electricity. In the embodiment shown byFIG. 1, the main air compressor12and the master turbine compressor30may be driven by the power generated by the master turbine34via the master turbine shaft22.

In some embodiments, the main air compressor12may further comprise adjustable inlet guide vanes to control the flow of air into the main air compressor12. The inlet guide vanes of the main air compressor may be used to regulate the flow and the pressure of the at least a first portion of the compressed ambient gas flow26that is delivered to the master turbine combustor32. In some embodiments, the master turbine compressor30may further comprise adjustable inlet guide vanes to control the flow of air into the master turbine compressor30. The inlet guide vanes of the master turbine compressor30may be used to regulate the output pressure and the flow delivered to the master turbine combustor32from the master turbine compressor30as the at least a first portion of the master recirculated gas flow50.

As used herein, the term “master recirculated gas flow” refers to the gas flow generated by the burning of the master combustible mixture in the master turbine combustor32and flowing through a master recirculation loop52. In some embodiments, the master recirculated gas flow50may have a low oxygen content. As used herein, the term “low oxygen content” refers to an oxygen content of below about 5 vol %, below about 2 vol %, or below about 1 vol %.

As used herein, the term “gas turbine assembly” refers to all listed components of the power plant arrangements except for the main air compressor12. In embodiments comprising multiple main air compressors, the term “gas turbine assembly” refers to all listed components of the power plant arrangements except for the multiple main air compressors.

In some embodiments, the master recirculated gas flow50may be directed from the master turbine combustor32through the master recirculation loop52to a master heat recovery steam generator36for the generation of steam. A master steam turbine may further be configured to generate additional electricity using the steam from the master heat recovery steam generator36, and the master steam turbine may be connected to a master steam generator. In some embodiments, the master heat recovery steam generator36, in conjunction with the master steam turbine and the master steam generator, may be configured to generate additional electricity when the temperature of the master recirculated gas flow50is in the range from about 200° C. to about 700° C., from about 260° C. to about 600° C., or from about 300° C. to about 550° C. In some embodiments, the master steam turbine may be arranged to be connected to the master turbine shaft22. The master recirculated gas flow50may then be directed back into the master recirculation loop52to a master recirculated gas flow cooler40. In still other embodiments, the master recirculation loop52may not contain a master heat recovery steam generator36and the master recirculated gas flow50may instead be introduced directly into the master recirculated gas flow cooler40upon exit from the master turbine34. In other embodiments, the master recirculation loop52may not comprise the master recirculated gas flow cooler40.

The master recirculated gas flow cooler40may be incorporated into the master recirculation loop52anywhere downstream of the master turbine34. The master recirculated gas flow cooler40may be configured to lower the temperature of the master recirculated gas flow50to a suitable temperature for downstream delivery into the master turbine compressor30via the master recirculation loop52. In some embodiments, a suitable temperature may be below about 66° C., below about 49° C., or below about 45° C.

In some embodiments, a master blower42may be fluidly connected to the master recirculation loop52upstream of the master recirculated gas flow cooler40. The master blower42may be configured to increase the pressure of the master recirculated gas flow50prior to delivery into the master recirculated gas flow cooler40via the master recirculation loop52.

In some embodiments, the exemplary power plant arrangement10may include a master bypass conduit49located downstream of the master turbine compressor30and may be in fluid connection with a portion of the master recirculated gas flow50via a master turbine compressor exhaust44. In some embodiments, a master bypass flow through the master bypass conduit49may be regulated by a master turbine bypass valve47. The master turbine bypass valve47may be used to adjust a master bypass flow rate through the master bypass conduit49. In some embodiments, the master bypass conduit49may be used to bypass the master turbine combustor32with at least a second portion of the master recirculated gas flow50.

In some embodiments, the master bypass flow may be fluidly connected to the master recirculation loop52downstream of the master turbine34. In still other embodiments, a portion of the master bypass flow into the master bypass conduit49may be extracted as a master extraction flow48and regulated by a master extraction valve45.

In some embodiments, the master extraction valve45may be fluidly connected to the master bypass conduit49at a point that is either upstream of or downstream of the master turbine bypass valve47. In some embodiments, the master bypass extraction valve may be fluidly connected to a secondary process. In some embodiments, the master extraction valve45may be fluidly connected to a master gas separation system such as a carbon capture sequestration (CCS) system via the master extraction flow48. In still other embodiments, the master gas separation system may produce a stream of concentrated carbon dioxide and concentrated nitrogen, both with a low oxygen content.

In some embodiments, a master gas turbine vent to the atmosphere may be in fluid communication with the master gas turbine assembly and may be located anywhere between an output of the master turbine compressor30and an input of the master turbine compressor30. In some embodiments, the power plant arrangement10may include a master damper door38connected to the master recirculation loop52. The master damper door38may be opened to vent a portion of the master recirculated gas flow50to the atmosphere. In some embodiments, an excess portion of the master recirculated gas flow50may be vented from the master bypass conduit49.

In some embodiments, the gas turbine assembly may further comprise a master secondary flow path31that may deliver at least a third portion of the master recirculated gas flow50from the master turbine compressor30to the master turbine34as a secondary flow. The secondary flow may be used to cool and to seal the master turbine34, including individual components of the master turbine34such as the turbine shroud, the turbine nozzle, the turbine blade tip, the turbine bearing support housing, and the like. After cooling and sealing the master turbine34and any individual master turbine components, the secondary flow may be directed into the master recirculation loop52near the output of the master turbine34.

As illustrated byFIG. 1, in some embodiments, the turbine shaft22may be a “cold-end drive” configuration, meaning the turbine shaft22may connect to the generator20at the compressor end of the turbine assembly. In other embodiments, the turbine shaft22may be a “hot-end drive” configuration, meaning the turbine shaft22may connect to the generator20at the turbine end of the turbine assembly.

As used herein, the term “slave” is synonymous with the terms secondary, auxiliary, or additional. In the following embodiments, the term “slave” refers to the second of two gas turbine assemblies, but can also mean any additional gas turbine assemblies operated with a master gas turbine assembly such as is the second gas turbine assembly in the following embodiments.

In some embodiments, the main air compressor12may deliver compressed ambient gas to a slave turbine combustor72that may be fluidly connected to the main air compressor12via an inter-train conduit19. The flow of the compressed ambient gas through the inter-train conduit19may be further regulated by an inter-train valve16to create at least a second portion of a compressed ambient gas flow66. The at least a second portion of the compressed ambient gas flow66may further be vented to the atmosphere via a slave variable bleed valve18. The flow of the at least a second portion of the compressed ambient gas flow66to a slave turbine combustor72may be regulated by a slave air injection valve65.

The slave turbine combustor72may be configured to receive the at least a second portion of the compressed ambient gas flow66from the main air compressor12, a slave recirculated gas flow90from a slave turbine compressor70, and a slave fuel stream68, to form a slave combustible mixture and to burn the slave combustible mixture to generate the slave recirculated gas flow90. In some embodiments, the slave fuel stream68may be regulated by a slave gas control valve67to deliver a slave fuel flow rate. In addition, the exemplary power plant arrangement10may include a slave turbine74located downstream of the slave turbine combustor72. The slave turbine74may be configured to expand the slave recirculated gas flow90and may drive an external load such as a slave turbine generator60via a slave turbine shaft62to generate electricity.

In some embodiments, the slave turbine compressor70may further comprise adjustable inlet guide vanes to control the flow of air into the slave turbine compressor70. The inlet guide vanes of the slave turbine compressor70may be used to regulate the output pressure and the flow delivered to the slave turbine combustor72from the slave turbine compressor70as the slave recirculated gas flow90.

As used herein, the term “slave recirculated gas flow” refers to the gas flow generated by the burning of the slave combustible mixture in the slave turbine combustor72and flowing through a slave recirculation loop92. In some embodiments, the slave recirculated gas flow90may comprise a low oxygen content. As used herein, the term “low oxygen content” refers to an oxygen content of below about 5 vol %, below about 2 vol %, or below about 1 vol %.

In some embodiments, the slave recirculated gas flow90may be directed from the slave turbine combustor72through the slave recirculation loop92to a slave heat recovery steam generator76for the generation of steam. A slave steam turbine may be further configured to generate additional electricity using the steam from the slave heat recovery steam generator76, and the slave steam turbine may be connected to a slave steam generator. In some embodiments, the slave heat recovery steam generator76, in conjunction with the slave steam turbine and the slave steam generator, may be configured to generate additional electricity when the temperature of the slave recirculated low oxygen content gas flow90is in the range from about 200° C. to about 700° C., from about 260° C. to about 600° C., or from about 300° C. to about 550° C. In some embodiments, the slave steam turbine may be arranged to be connected to the slave turbine shaft62. The slave recirculated gas flow90may then be directed back into the slave recirculation loop92to a slave recirculated gas flow cooler80. In still other embodiments, the recirculation loop92may not contain a slave heat recovery steam generator76and the slave recirculated low oxygen content gas flow90may instead be introduced directly into the slave recirculated gas flow cooler80upon exit from the slave turbine74. In some embodiments, the slave recirculation loop92may not comprise a slave recirculated gas flow cooler80.

The slave recirculated gas flow cooler80may be incorporated into the slave recirculation loop92anywhere downstream from the slave turbine74. The slave recirculated gas flow cooler80may be configured to lower the temperature of the slave recirculated low oxygen content gas flow90to a suitable temperature for downstream delivery into the slave turbine compressor70via the slave recirculation loop92. In some embodiments, a suitable temperature may be below about 66° C., below about 49° C., or below about 45° C.

In some embodiments, a slave blower82may be fluidly connected to the slave recirculation loop92upstream of the slave recirculated gas flow cooler80. The slave blower82may be configured to increase the pressure of the slave recirculated gas flow90prior to delivery into the slave turbine compressor70via the slave recirculation loop92.

In some embodiments, the exemplary power plant arrangement10may include a slave bypass conduit89located downstream of the slave turbine compressor70and may be in fluid connection with a portion of the slave recirculated gas flow90via a turbine compressor exhaust84. In some embodiments, a slave bypass flow through the slave bypass conduit89may be regulated by a slave turbine bypass valve87. In some embodiments, a portion of the slave bypass flow into the slave bypass conduit89may be extracted as a slave extraction flow88and regulated by a slave extraction valve85. In some embodiments, the slave bypass conduit89may be used to bypass the slave turbine combustor72with at least a second portion of the slave recirculated gas flow90.

In some embodiments, the slave bypass flow may be fluidly connected to the slave recirculation loop92downstream of the slave turbine74. In still other embodiments, a portion of the slave bypass flow into the slave bypass conduit89may be extracted as a slave extraction flow88and regulated by a slave extraction valve85.

In some embodiments, the slave extraction valve85may be fluidly connected to the slave bypass conduit89at a point that is either upstream of or downstream of the slave turbine bypass valve87. In some embodiments, the slave extraction flow88may be used for a secondary process. In some embodiments, the slave extraction valve85may be fluidly connected to a slave gas separation system such as a carbon capture sequestration (CCS) system via the slave extraction flow88. In still other embodiments, the slave gas separation system may produce a stream of concentrated carbon dioxide and concentrated nitrogen, both with a low oxygen content.

In some embodiments, a slave gas turbine vent to the atmosphere may be in fluid communication with the slave gas turbine assembly and may be located anywhere between an output of the slave turbine compressor70and an input of the slave turbine compressor70. In some embodiments, the power plant arrangement10may include a slave damper door78connected to the slave recirculation loop92. The slave damper door78may be opened to vent a portion of the slave recirculated gas flow90to the atmosphere. In some embodiments, an excess portion of the slave recirculated gas flow90may be vented from the slave bypass conduit89.

In some embodiments, the gas turbine assembly may further comprise a slave secondary flow path71that may deliver at least a third portion of the slave recirculated gas flow90from the slave turbine compressor70to the slave turbine74as a slave secondary flow. The slave secondary flow may be used to cool and to seal the slave turbine74, including individual components of the slave turbine74such as the turbine shroud, the turbine nozzle, the turbine blade tip, the turbine bearing support housing, and the like. After cooling and sealing the slave turbine74and any individual slave turbine components, the slave secondary flow may be directed into the slave recirculation loop92downstream of the slave turbine74.

As illustrated byFIG. 1, in some embodiments, the slave turbine shaft62may be a “cold-end drive” configuration, meaning the slave turbine shaft62may connect to the slave generator60at the compressor end of the turbine assembly. In other embodiments, the slave turbine shaft62may be a “hot-end drive” configuration, meaning the slave turbine shaft62may connect to the slave generator60at the turbine end of the turbine assembly.

FIG. 2is a diagrammatical illustration of an exemplary configuration100of the exemplary power plant arrangement10ofFIG. 1. As discussed with reference toFIG. 1, a booster compressor24may be incorporated downstream of and in fluid connection with the main air compressor12and upstream of and in fluid connection with the master turbine combustor32. The booster compressor24may further compress the at least a first portion of the compressed ambient gas flow26before delivery into the turbine combustor32. Similarly, a slave booster compressor64may be incorporated downstream of and in fluid connection with the main air compressor12and upstream of and in fluid connection with the slave turbine combustor72. The slave booster compressor64may further compress the at least a second portion of the compressed ambient gas flow66before delivery into the slave turbine combustor72.

In some embodiments, the power plant arrangement may comprise two gas turbine assemblies that are fluidly connected by the inter-train conduit19. As used herein, the term “inter-train conduit” may refer to a fluid connection between two or more gas turbine assemblies and one or more main air compressors. In still other embodiments, the power plant arrangement may comprise three or more gas turbine assemblies and one or more additional main air compressors, wherein the additional main air compressors are in fluid connection with each other and with the gas turbine assemblies. In yet other embodiments, the power plant arrangement may be configured for substantially stoichiometric combustion. In still other embodiments, the power plant arrangement may be configured for substantially zero emissions power production.

In some embodiments, the fuel stream28and/or the slave fuel stream68may comprise an organic gas, including but not limited to methane, propane, and/or butane. In still other embodiments, the fuel stream28and/or the slave fuel stream68may comprise an organic liquid, including but not limited to methanol and/or ethanol. In yet other embodiments, the fuel stream28and/or the slave fuel stream68may comprise a fuel source obtained from a solid carbonaceous material such as coal.

Method for Operating a Power Plant

In one embodiment, a method for operating the exemplary power plant arrangement10is provided, wherein the inter-train valve16may be open. In operation, ambient air may be compressed with a main air compressor12to make at least a first portion of a compressed ambient gas flow26and at least a second portion of a compressed ambient gas flow66. The at least a first portion of the compressed ambient gas flow26may be delivered from the main air compressor12to the master turbine combustor32and may be regulated by a master air injection valve25. In some embodiments, the at least a first portion of the compressed ambient gas flow26may further be regulated by a master variable bleed valve14.

The at least a first portion of the compressed ambient gas flow26may be mixed, in the master turbine combustor32, with the master recirculated gas flow50and with the master fuel stream28to form a master combustible mixture. In some embodiments, the master fuel flow rate of the master fuel stream28may be regulated by a master gas control valve27. The master combustible mixture may then ignited and burned in the master turbine combustor32, thereby forming the master recirculated gas flow50and driving both the master turbine34and the master turbine compressor30.

In some embodiments, the at least a second portion of the compressed ambient gas flow66may be delivered from the main air compressor12to the slave turbine combustor72and may be regulated by a slave air injection valve65. In some embodiments, the at least a second portion of the compressed ambient gas flow66may be further regulated by a slave variable bleed valve18. The at least a second portion of the compressed ambient gas flow66may be mixed, in the slave turbine combustor72, with the slave recirculated gas flow90and with the slave fuel stream68to form a slave combustible mixture. In some embodiments, the slave fuel flow rate of the slave fuel stream68may be regulated by a slave gas control valve67. The slave combustible mixture may then be ignited and burned in the slave turbine combustor72, thereby forming the slave recirculated gas flow90and driving both the slave turbine74and the slave turbine compressor70.

As used herein, the term “driving” means the expansion of the recirculated gas flow50in the turbine34thereby causing the turbine34to rotate. The master turbine34may be connected to the turbine compressor30via the turbine shaft22, and thus rotation of the turbine34causes rotation of the turbine compressor30. The turbine shaft22may also rotate in a turbine generator20and may further generate electricity. Additionally, the term “driving” also means the expansion of the slave recirculated gas flow90in the slave turbine74thereby causing the slave turbine74to rotate. The slave turbine74may be connected to the slave turbine compressor70via the slave turbine shaft62, and thus rotation of the slave turbine74causes rotation of the slave turbine compressor70. The slave turbine shaft62may also rotate in a slave turbine generator60and may further generate electricity.

In some embodiments, at least a portion of the master recirculated gas flow50may be recirculated through a master recirculation loop52. The master recirculation loop52may fluidly connect the output of the master turbine34with the input of the master turbine compressor30. The master recirculated gas flow50may further pass through the master heat recovery steam generator36, the master recirculated gas flow cooler40, and the master turbine blower42en route from the output of the master turbine34to the input of the master turbine compressor30.

In some embodiments, at least a portion of the slave recirculated gas flow90may be recirculated through a slave recirculation loop92. The slave recirculation loop92may fluidly connect the output of the slave turbine74with the input of the slave turbine compressor70. The slave recirculated gas flow90may further pass through the slave heat recovery steam generator76, the slave recirculated gas flow cooler80, and the slave turbine blower82en route from the output of the slave turbine74to the input of the slave turbine compressor70.

An excess portion, if any, of the master recirculated gas flow50may be vented from the system at a location between an output of the master turbine compressor30and an input to the master turbine compressor30. The venting step may be used to prevent over-pressurization of the master gas turbine assembly. In some embodiments, the venting step may be used to reduce the pressure of the master recirculated gas flow50that is delivered from the master turbine compressor30to the master turbine combustor32. In some embodiments, the method of operation may further comprise opening a master damper door38, which may be fluidly connected to the master recirculation loop52, to the atmosphere. In some embodiments, an excess portion of the master recirculated gas flow50may be vented from the master bypass conduit49.

An excess portion, if any, of the slave recirculated gas flow90may be vented from the system at a location between an output of the slave turbine compressor70and an input to the slave turbine compressor70. The venting step may be used to prevent over-pressurization of the slave gas turbine assembly. In some embodiments, the venting step may be used to reduce the pressure of the slave recirculated gas flow90that is delivered from the slave turbine compressor70to the slave turbine combustor72. In some embodiments, the method of operation may further comprise opening a slave damper door78, which may be fluidly connected to the slave recirculation loop92, to the atmosphere. In some embodiments, an excess portion of the slave recirculated gas flow90may be vented from the slave bypass conduit89.

In some embodiments, at least a portion of a master turbine compressor exhaust44may bypass the master turbine combustor32via the master bypass conduit49. As used herein, the “exhaust” of the master turbine compressor30is an output of the master recirculated gas flow50from the master turbine compressor30. A master bypass flow with a master bypass flow rate may be regulated by the master turbine bypass valve47. Additionally, the master bypass conduit49may deliver the master bypass flow to the master recirculation loop52downstream of the master turbine34. In some embodiments, the master bypass conduit49may be used to bypass the master turbine combustor32with at least a second portion of the master recirculated gas flow50.

In some embodiments, a portion of the master bypass flow into the master bypass conduit49may be extracted as a master extraction flow48and may be regulated by a master extraction valve45. In some embodiments, the master extraction valve45may be fluidly connected to the master bypass conduit49at a point that is either upstream of or downstream of the master turbine bypass valve47. In some embodiments, the master extraction flow48may be used for one or more secondary processes. In some embodiments, the master extraction flow48may be delivered to a master gas separation system. In some embodiments, the master extraction valve45may be fluidly connected to a master gas separation system such as a carbon capture sequestration (CCS) system via the master extraction flow48. In still other embodiments, the master gas separation system may produce a stream of concentrated carbon dioxide and concentrated nitrogen, both with a low oxygen content.

In some embodiments, at least a portion of a slave turbine compressor exhaust84may bypass the slave turbine combustor72via the slave bypass conduit89. As used herein, the “exhaust” of the slave turbine compressor70is an output of the slave recirculated gas flow90from the slave turbine compressor70. A slave bypass flow with a slave bypass flow rate may be regulated by the slave turbine bypass valve87. Additionally, the slave bypass conduit89may deliver the slave bypass flow to the slave recirculation loop92downstream of the slave turbine74. In some embodiments, the slave bypass conduit89may be used to bypass the slave turbine combustor72with at least a second portion of the slave recirculated gas flow90.

In some embodiments, a portion of the slave bypass flow into the slave bypass conduit89may be extracted as a slave extraction flow88and may be regulated by a slave extraction valve85. In some embodiments, the slave extraction valve85may be fluidly connected to the slave bypass conduit89at a point that is either upstream of or downstream of the slave turbine bypass valve87. In some embodiments, the slave extraction flow88may be used for one or more secondary processes. In some embodiments, the slave extraction flow88may be delivered to a slave gas separation system. In some embodiments, the slave extraction valve85may be fluidly connected to a slave gas separation system such as a carbon capture sequestration (CCS) system via the slave extraction flow88. In still other embodiments, the slave gas separation system may produce a stream of concentrated carbon dioxide and concentrated nitrogen, both with a low oxygen content.

In some embodiments, the master turbine power generated by the combustion of the master combustible mixture may be used to rotate a master turbine shaft22that may be configured to generate electricity when rotated in the master turbine generator20. In some embodiments, the electricity may be generated using substantially stoichiometric combustion. In some embodiments, the slave turbine power generated by the combustion of the slave combustible mixture may be used to rotate a slave turbine shaft62that may be configured to generate electricity when rotated in the slave turbine generator60. In some embodiments, the electricity may be generated using substantially stoichiometric combustion.

In some embodiments, the master gas turbine assembly may further comprise a master secondary flow path31that may deliver at least a third portion of the master recirculated gas flow50from the master turbine compressor30to the master turbine34as a master secondary flow. The master secondary flow may be used to cool and to seal the master turbine34, including individual components of the master turbine34such as the turbine shroud, the turbine nozzle, the turbine blade tip, the turbine bearing support housing, and the like. After cooling and sealing the master turbine34and any individual master turbine components, the master secondary flow may be directed into the master recirculation loop52downstream of the master turbine34.

Similarly, in some embodiments the slave gas turbine assembly may further comprise a slave secondary flow path71that may deliver at least a third portion of the slave recirculated gas flow90from the slave turbine compressor70to the slave turbine74as a slave secondary flow. The slave secondary flow may be used to cool and to seal the slave turbine74, including individual components of the slave turbine74such as the turbine shroud, the turbine nozzle, the turbine blade tip, the turbine bearing support housing, and the like. After cooling and sealing the slave turbine74and any individual slave turbine components, the slave secondary flow may be directed into the slave recirculation loop92downstream of the slave turbine74.

In some embodiments, a method for operating an exemplary power plant configuration100is provided and may include the use of the master booster compressor24which may be incorporated downstream of and in fluid connection with the main air compressor12and upstream of and in fluid connection with the master turbine combustor32. The master booster compressor24may further compress the at least a first portion of the compressed ambient gas flow26before delivery into the master turbine combustor32. The exhaust of the master booster combustor24may be delivered to the master turbine combustor32. In some embodiments, the exhaust of the master booster compressor24may be regulated by the master air injection valve25.

In some embodiments, a method for operating the exemplary power plant configuration100is provided and may include the use of the slave booster compressor64which may be incorporated downstream of and in fluid connection with the main air compressor12and upstream of and in fluid connection with the slave turbine combustor72. The slave booster compressor64may further compress the at least a second portion of the compressed ambient gas flow66before delivery into the slave turbine combustor72. The exhaust of the slave booster combustor64may be delivered to the slave turbine combustor72. In some embodiments, the exhaust of the slave booster compressor64may be regulated by the slave air injection valve65.

Method for Operating a Power Plant at Constant Speed No Load

In another embodiment, a method for operating an exemplary power plant arrangement10at constant speed no load is provided, wherein the inter-train valve16may be open.

Constant speed no load operation of the master turbine assembly may consider several factors for operation. First, the master power produced by the master turbine34should be equal to the power consumed by the main air compressor12(if attached to the master turbine shaft22) plus the power consumed by the master turbine compressor30. Second, the master exhaust gas temperature of the master gas turbine assembly may be maintained at an appropriate temperature to enable the master heat recovery steam generator36to operate. Third, the pressure of the at least a first portion of the compressed ambient gas flow26entering the master turbine combustor32should be greater than or substantially equal to the pressure of the master recirculated gas flow50entering the master turbine combustor32from the master turbine compressor30. Fourth, there should be sufficient oxygen from the combination of the at least of first portion of the compressed ambient gas flow26and the master recirculated gas flow50such that combustion may proceed in the master turbine combustor32without a lean blow-out.

Similarly, constant speed no load operation of the slave turbine assembly may consider several factors for operation. First, the slave power produced by the slave turbine74should be equal to the power consumed by the slave turbine compressor30. Second, the slave exhaust gas temperature of the slave gas turbine assembly may be maintained at an appropriate temperature to enable the slave heat recovery steam generator76to operate. Third, the pressure of the at least a second portion of the compressed ambient gas flow66entering the slave turbine combustor72should be greater than or substantially equal to the pressure of the slave recirculated gas flow90entering the slave turbine combustor72from the slave turbine compressor70. Fourth, there should be sufficient oxygen from the combination of the at least a second portion of the compressed ambient gas flow66and the slave recirculated gas flow90such that combustion may proceed in the slave turbine combustor72without a lean blow-out.

Additionally, each element of equipment described above in the section “Power Plant Arrangement” may influence constant speed no load operation. At constant speed no load operation, the master turbine34is rotating at a constant speed but the master turbine generator20is not engaged to generate electricity. In some embodiments, the main air compressor12may have inlet guide vanes set to allow the minimum flow necessary to match or exceed the pressure of the flow from the master turbine compressor30. In some embodiments, the master turbine compressor30may have inlet guide vanes set to allow the minimum flow necessary to provide any necessary remainder flow not provided by the main air compressor12to the master turbine combustor32. The master variable bleed valve14may be closed. The inter-train valve16is open. The master fuel flow rate of the master fuel stream28may be set in conjunction with the combination of the flow rates of the at least a first portion of the compressed ambient gas flow26and the master recirculated gas flow50to provide sufficient master turbine power through combustion. Additionally, any excess portion of the master recirculated flow50may be vented from the master gas turbine assembly so that the master gas turbine assembly does not over-pressurize.

Similarly, each element of equipment described above in the section “Power Plant Arrangement” for the slave gas turbine assembly may influence constant speed no load operation. At constant speed no load operation, the slave turbine74is rotating at a constant speed but the slave turbine generator60is not engaged to generate electricity. The slave turbine compressor70may have inlet guide vanes set to allow the minimum flow necessary to provide any necessary remainder flow not provided by the main air compressor12to the slave turbine combustor72. The slave variable bleed valve18may be closed. The slave fuel flow rate of the slave fuel stream68may be set in conjunction with the combination of the flow rates of the at least a second portion of the compressed ambient gas flow66and the slave recirculated gas flow90to provide sufficient slave turbine power through combustion. Additionally, any excess portion of the slave recirculated gas flow90may be vented from the slave gas turbine assembly so that the slave gas turbine assembly does not over-pressurize.

In some embodiments, discussed in detail below, a master bypass conduit49may be used to “bleed” extra pressure from the master turbine compressor30as a master bypass flow. The master bypass flow may be regulated by a master turbine bypass valve47. The flow across the master turbine34may be equal to the flow rate from the master turbine compressor30multiplied by one minus the master turbine bypass valve opening percentage, plus the flow rate of the at least a first portion of the compressed ambient gas flow26plus the flow rate of the master fuel stream26. The master turbine power may then be equal to the flow across the master turbine34multiplied by the specific work extracted across the master turbine34. The specific work extracted from the master turbine34may be proportional to the pressure and temperature drop across the master turbine34. The temperature drop across the master turbine section may be influenced by the master turbine34inlet temperature, which may be influenced by the fuel flow into the master turbine combustor32.

Similarly, and as discussed in detail below, in some embodiments, a slave bypass conduit89may be used to “bleed” extra pressure from the slave turbine compressor70as a slave bypass flow. The slave bypass flow may be regulated by a slave turbine bypass valve87. The flow across the slave turbine74may be equal to the flow rate from the slave turbine compressor70multiplied by one minus the slave turbine bypass valve opening percentage, plus the flow rate of the at least a second portion of the compressed ambient gas flow66plus the flow rate of the slave fuel stream66. The slave turbine power may then be equal to the flow across the slave turbine74multiplied by the specific work extracted across the slave turbine74. The specific work extracted from the slave turbine74may be proportional to the pressure and temperature drop across the slave turbine74. The temperature drop across the slave turbine section may be influenced by the slave turbine74inlet temperature, which may be influenced by the fuel flow into the slave turbine combustor72.

In operation, ambient air may be compressed with the main air compressor12to make at least a first portion of a compressed ambient gas flow26having a first compressed ambient gas flow rate. In some embodiments, the inlet guide vanes to the main air compressor12may be used to control the compressed ambient gas flow rate and may be adjusted to a range of about 30° to about 55°, from about 35° to about 50°, or from about 40° to about 45°.

The at least a first portion of the compressed ambient gas flow26may be delivered from the main air compressor12to the master turbine combustor32and the flow may be further regulated by a master air injection valve25. In some embodiments, the flow of the at least a first portion of the compressed ambient gas flow26may additionally be regulated by the master variable bleed valve14. The first compressed ambient gas flow rate may be adjusted to control the pressure at which the first portion of the compressed ambient gas flow26is delivered to the master turbine combustor32.

Ambient air may also be compressed with the main air compressor12to provide at least a second portion of a compressed ambient gas flow66having a second compressed ambient gas flow rate. The at least a second portion of the compressed ambient gas flow66may be delivered from the main air compressor12to the slave turbine combustor72and the flow may be further regulated by a slave air injection valve65. In some embodiments, the flow of the at least a second portion of the compressed ambient gas flow66may additionally be regulated by the slave variable bleed valve18. The second compressed ambient gas flow rate may be adjusted to control the pressure at which the second portion of the compressed ambient gas flow66is delivered to the slave turbine combustor72.

The at least a first portion of the compressed ambient gas flow26may be delivered from the main air compressor12to the master turbine combustor32at a pressure that is greater than or substantially equal to an output pressure that is delivered to the master turbine combustor32from a master turbine compressor30as at least a first portion of a master recirculated gas flow50having a master recirculated gas flow rate. A master fuel stream28may also be delivered to the master turbine combustor32with a master fuel flow rate. In embodiments, the master fuel flow rate, the first compressed ambient gas flow rate, and the master recirculated gas flow rate may be sufficient to maintain combustion in the master turbine combustor32.

The at least a second portion of the compressed ambient gas flow66may be delivered from the main air compressor12to the slave turbine combustor72at a pressure that is greater than or substantially equal to an output pressure that is delivered to the slave turbine combustor72from a slave turbine compressor70as at least a first portion of a slave recirculated gas flow90having a slave recirculated low oxygen content gas flow rate. A slave fuel stream68may also be delivered to the slave turbine combustor72with a slave fuel flow rate. In embodiments, the slave fuel flow rate, the second compressed ambient gas flow rate, and the slave recirculated gas flow rate may be sufficient to maintain combustion in the slave turbine combustor72.

The at least a first portion of a master recirculated gas flow50has a flow rate that may be adjusted. Adjusting the flow rate of the at least a first portion of the master recirculated gas flow50may control the output pressure that is delivered from the master turbine compressor30to the master turbine combustor32. In some embodiments, the inlet guide vanes of the master turbine compressor30may be used to adjust the master recirculated low oxygen content gas flow rate. In some embodiments, the inlet guide vanes of the master turbine compressor30may be adjusted to a range of about 35° to about 65°, about 40° to about 60°, or about 45° to about 55°.

The at least a first portion of a slave recirculated gas flow90has a flow rate that may be adjusted. Adjusting the flow rate of the at least a first portion of the slave recirculated gas flow90may control the output pressure that is delivered from the slave turbine compressor70to the slave turbine combustor72. In some embodiments, the inlet guide vanes of the slave turbine compressor70may be used to adjust the slave recirculated gas flow rate. In some embodiments, the inlet guide vanes of the slave turbine compressor70may be adjusted to a range of about 35° to about 65°, about 40° to about 60°, or about 45° to about 55°.

The master fuel flow rate of the master fuel stream28may be regulated by a master gas control valve27to give a master fuel flow rate in the range of about 10 pps to about 30 pps, about 15 pps to about 25 pps, or from about 18 pps to about 22 pps. The slave fuel flow rate of the slave fuel stream68may be regulated by a slave gas control valve27to give a slave fuel flow rate in the range of about 10 pps to about 30 pps, about 15 pps to about 25 pps, or from about 18 pps to about 22 pps. As used herein, the term “pps” means pounds per second and specifies a flow rate by mass.

The at least a first portion of the compressed ambient gas flow26may be mixed, in the master turbine combustor32, with at least a first portion of the master recirculated gas flow50and with the master fuel stream28to form a master combustible mixture. The master combustible mixture may then be ignited and burned in the master turbine combustor32, thereby forming the master recirculated gas flow50and driving both the master turbine34and the master turbine compressor30, and producing a master turbine power that is substantially equal to at least the power required to rotate the master turbine compressor30. As used herein, the term “driving” means that both the master turbine34and the master turbine compressor30rotate. Thus, the burning of the master combustible mixture may produce a master turbine power that is substantially equal to at least a power required to rotate the master turbine compressor30.

The at least a second portion of the compressed ambient gas flow66may be mixed, in the slave turbine combustor72, with at least a first portion of the slave recirculated gas flow90and with the slave fuel stream68to form a slave combustible mixture. The slave combustible mixture may then be ignited and burned in the slave turbine combustor72, thereby forming the slave recirculated gas flow90and driving both the slave turbine74and the slave turbine compressor70, and producing a slave turbine power that is substantially equal to at least the power required to rotate the slave turbine compressor70. As used herein, the term “driving” means that both the slave turbine74and the slave turbine compressor70rotate. Thus, the burning of the slave combustible mixture may produce a slave turbine power that is substantially equal to at least a power required to rotate the slave turbine compressor70.

At least a portion of the master recirculated gas flow50may be recirculated through a master recirculation loop52. The master recirculation loop52may fluidly connect an output of the master turbine34with an input of the master turbine compressor30. The master recirculated gas flow50may further pass through the master heat recovery steam generator36, the master recirculated gas flow cooler40, and the master turbine blower42en route from the output of the master turbine34to the input of the master turbine compressor30.

At least a portion of the slave recirculated gas flow90may be recirculated through a slave recirculation loop92. The slave recirculation loop92may fluidly connect an output of the slave turbine74with an input of the slave turbine compressor70. The slave recirculated low oxygen content gas flow90may further pass through the slave heat recovery steam generator76, the slave recirculated gas flow cooler80, and the slave turbine blower82en route from the output of the slave turbine74to the input of the slave turbine compressor70.

In some embodiments, the master recirculated gas flow50may be directed through the master heat recovery steam generator36for the generation of steam. A master steam turbine may be further configured to generate additional electricity using the steam from the master heat recovery steam generator36, and the master steam turbine may be connected to a master steam generator. In some embodiments, the master heat recovery steam generator36, in conjunction with the master steam turbine and the master steam generator, may be configured to generate additional electricity when the temperature of the master recirculated gas flow50is in the range from about 200° C. to about 700° C., from about 260° C. to about 600° C., or from about 300° C. to about 550° C. In some embodiments, the master steam turbine may be connected to the master turbine shaft22.

In some embodiments, the slave recirculated gas flow90may be directed through the slave heat recovery steam generator76for the generation of steam. A slave steam turbine may be further configured to generate additional electricity using the steam from the slave heat recovery steam generator76, and the slave steam turbine may be connected to a slave steam generator. In some embodiments, the slave heat recovery steam generator76, in conjunction with the slave steam turbine and the slave steam generator, may be configured to generate additional electricity when the temperature of the slave recirculated gas flow90is in the range from about 200° C. to about 700° C., from about 260° C. to about 600° C., or from about 300° C. to about 550° C. In some embodiments, the slave steam turbine may be connected to the slave turbine shaft62.

An excess portion of the master recirculated gas flow50may be vented from the master gas turbine assembly at a location between an output of the master turbine compressor30and an input to the master turbine compressor30. The venting step may be used to prevent over-pressurization of the master gas turbine assembly. In some embodiments, the venting step may be used to reduce the pressure of the master recirculated gas flow50that is delivered from the master turbine compressor30to the master turbine combustor32. In some embodiments, the method of venting may further comprise opening a master damper door38, which may be fluidly connected to the master recirculation loop52, to the atmosphere. In some embodiments, an excess portion of the master recirculated gas flow50may be vented from the master bypass conduit49.

An excess portion of the slave recirculated gas flow90may be vented from the slave gas turbine assembly at a location between an output of the slave turbine compressor70and an input to the slave turbine compressor70. The venting step may be used to prevent over-pressurization of the slave gas turbine assembly. In some embodiments, the venting step may be used to reduce the pressure of the slave recirculated gas flow90that is delivered from the slave turbine compressor70to the slave turbine combustor72. In some embodiments, the method of venting may further comprise opening a slave damper door78, which may be fluidly connected to the slave recirculation loop92, to the atmosphere. In some embodiments, an excess portion of the slave recirculated gas flow90may be vented from the slave bypass conduit89.

In some embodiments, at least a portion of an exhaust of the master turbine compressor30may bypass the master turbine combustor32via the master bypass conduit49. As used herein, the “exhaust” of the master turbine compressor30is an output of the master recirculated gas flow50from the master turbine compressor30. Additionally, the master bypass conduit49may deliver the master bypass flow to the master recirculation loop52downstream of the master turbine34. In some embodiments, the exhaust of the master turbine compressor30may bypass the master turbine combustor32as a master bypass flow having a master bypass flow rate, wherein the master bypass flow rate may be adjusted. In some embodiments, the master bypass conduit49may be used to bypass the master turbine combustor32with at least a second portion of the master recirculated gas flow50. In some embodiments, the master bypass flow rate may be adjusted using the master turbine bypass valve47. In some embodiments, the master turbine bypass valve47may be configured to deliver the master bypass flow with the master bypass flow rate in the range of about 20% to about 80%, from about 30% to about 70%, or from about 40% to about 60% of the output flow rate of the master turbine compressor30.

In some embodiments, at least a portion of an exhaust of the slave turbine compressor70may bypass the slave turbine combustor72via the slave bypass conduit89. As used herein, the “exhaust” of the slave turbine compressor70is an output of the slave recirculated gas flow90from the slave turbine compressor70. Additionally, the slave bypass conduit89may deliver the slave bypass flow to the slave recirculation loop92downstream of the slave turbine74. In some embodiments, the exhaust of the slave turbine compressor70may bypass the slave turbine combustor72as a slave bypass flow having a slave bypass flow rate, wherein the slave bypass flow rate may be adjusted. In some embodiments, the slave bypass conduit89may be used to bypass the slave turbine combustor72with at least a second portion of the slave recirculated gas flow90. In some embodiments, the slave bypass flow rate may be adjusted using the slave turbine bypass valve87. In some embodiments, the slave turbine bypass valve87may be configured to deliver the slave bypass flow with the slave bypass flow rate in the range of about 20% to about 80%, from about 30% to about 70%, or from about 40% to about 60% of the output flow rate of the slave turbine compressor70.

In some embodiments, a portion of the master bypass flow into the master bypass conduit49may be extracted as a master extraction flow48and may be regulated by a master extraction valve45. In some embodiments, the master extraction valve45may be fluidly connected to the master bypass conduit49at a point that is either upstream of or downstream of the master turbine bypass valve47. In some embodiments, the master extraction flow48may be used for a secondary process. In some embodiments, the master extraction flow48may be delivered to a master gas separation system. In some embodiments, the master extraction valve45may be fluidly connected to a master gas separation system such as a carbon capture sequestration (CCS) system via the master extraction flow48. In still other embodiments, the master gas separation system may produce a stream of concentrated carbon dioxide and concentrated nitrogen, both with a low oxygen content.

In some embodiments, a portion of the slave bypass flow into the slave bypass conduit89may be extracted as a slave extraction flow88and may be regulated by a slave extraction valve85. In some embodiments, the slave extraction valve85may be fluidly connected to the slave bypass conduit89at a point that is either upstream of or downstream of the slave turbine bypass valve87. In some embodiments, the slave extraction flow88may be used for a secondary process. In some embodiments, the slave extraction flow88may be delivered to a slave gas separation system. In some embodiments, the slave extraction valve85may be fluidly connected to a slave gas separation system such as a carbon capture sequestration (CCS) system via the slave extraction flow88. In still other embodiments, the slave gas separation system may produce a stream of concentrated carbon dioxide and concentrated nitrogen, both with a low oxygen content.

In some embodiments, the at least a first portion of the compressed ambient gas flow26may be delivered to the master turbine combustor32at a pressure that may be substantially equal to an output pressure from the master turbine compressor30to the master turbine combustor32. As used herein, the term “substantially equal” means a pressure difference that is less than about 10%, less than about 5%, or less than about 1%. In some embodiments, the at least a first portion of the compressed ambient gas flow26may be delivered to the master turbine combustor32at a pressure that may be greater than or substantially equal to an output pressure from the master turbine compressor30to the master turbine combustor32.

In some embodiments, the at least a second portion of the compressed ambient gas flow66may be delivered to the slave turbine combustor72at a pressure that may be substantially equal to an output pressure from the slave turbine compressor70to the slave turbine combustor72. As used herein, the term “substantially equal” means a pressure difference that is less than about 10%, less than about 5%, or less than about 1%. In some embodiments, the at least a second portion of the compressed ambient gas flow66may be delivered to the slave turbine combustor72at a pressure that may be greater than or substantially equal to an output pressure from the slave turbine compressor70to the slave turbine combustor72.

In some embodiments, the master turbine shaft22may connect the master turbine34to the master turbine compressor30. Under constant speed no load operation, the master turbine power that is produced by burning the master combustible mixture may be substantially equal to the power necessary to rotate the master turbine compressor30. In other embodiments, the master turbine shaft22may further connect to the main air compressor12, wherein the master turbine power that is produced by burning the master combustible mixture may be substantially equal to the power necessary to rotate both the master turbine compressor30and the main air compressor12.

In some embodiments, the slave turbine shaft62may connect the slave turbine74to the slave turbine compressor70. Under constant speed no load operation, the slave turbine power that is produced by burning the slave combustible mixture may be substantially equal to the power necessary to rotate the slave turbine compressor70.

In some embodiments, the master gas turbine assembly may further comprise a master secondary flow path31that may deliver at least a third portion of the master recirculated gas flow50from the master turbine compressor30to the master turbine34as a master secondary flow. The master secondary flow may be used to cool and to seal the master turbine34, including individual components of the master turbine34such as the turbine shroud, the turbine nozzle, the turbine blade tip, the turbine bearing support housing, and the like. After cooling and sealing the master turbine34and any individual master turbine components, the master secondary flow may be directed into the master recirculation loop52downstream of the master turbine34.

In some embodiments, the slave gas turbine assembly may further comprise a slave secondary flow path71that may deliver at least a third portion of the slave recirculated gas flow90from the slave turbine compressor70to the slave turbine74as a slave secondary flow. The slave secondary flow may be used to cool and to seal the slave turbine74, including individual components of the slave turbine74such as the turbine shroud, the turbine nozzle, the turbine blade tip, the turbine bearing support housing, and the like. After cooling and sealing the slave turbine74and any individual slave turbine components, the slave secondary flow may be directed into the slave recirculation loop92downstream of the slave turbine74.

In still other embodiments, a method for operating the exemplary power plant configuration100at constant speed no load is provided and may further include the use of the master booster compressor24which may be incorporated downstream of and in fluid connection with the main air compressor12and upstream of and in fluid connection with the master turbine combustor32. The master booster compressor24may further compress the at least a first portion of the compressed ambient gas flow26before delivery into the master turbine combustor32. The exhaust of the master booster combustor24may be delivered to the master turbine combustor32. In some embodiments, the exhaust of the master booster compressor24may be regulated by the master air injection valve25.

In some embodiments, a method for operating the exemplary power plant configuration100at constant speed no load is provided and may further include the use of the slave booster compressor64which may be incorporated downstream of and in fluid connection with the main air compressor12and upstream of and in fluid connection with the slave turbine combustor72. The slave booster compressor64may further compress the at least a second portion of the compressed ambient gas flow66before delivery into the slave turbine combustor72. The exhaust of the slave booster combustor64may be delivered to the slave turbine combustor72. In some embodiments, the exhaust of the slave booster compressor64may be regulated by the slave air injection valve65.

In some embodiments, the method comprises operating a power plant arrangement at constant speed no load that comprises two gas turbine assemblies that are fluidly connected by the inter-train conduit19. In some embodiments, both a master gas turbine assembly and a slave gas turbine assembly may be operated at the same constant speed. In other embodiments, a master and one or more slave gas turbine assemblies may each be operated at a different constant speed. In still other embodiments, the method comprises operating a power plant arrangement that comprises three or more gas turbine assemblies and one or more additional main air compressors, wherein the additional main air compressors are in fluid connection with each other and with the gas turbine assemblies. In yet other embodiments, the method comprises operating a power plant arrangement that is configured for substantially stoichiometric combustion. In still other embodiments, the method comprises operating a power plant arrangement that is configured for substantially zero emissions power production.

Other configurations and methods of operation are provided by U.S. patent applications including “Power Plant and Method of Use” to Daniel Snook, Lisa Wichmann, Sam Draper, and Noemie Dion Ouellet (filed Aug. 25, 2011), “Power Plant and Method of Operation” to Daniel Snook, Lisa Wichmann, Sam Draper, Noemie Dion Ouellet, and Scott Rittenhouse (filed Aug. 25, 2011), “Power Plant Start-Up Method” to Daniel Snook, Lisa Wichmann, Sam Draper, Noemie Dion Ouellet, and Scott Rittenhouse (filed Aug. 25, 2011), “Power Plant and Control Method” to Daniel Snook, Lisa Wichmann, Sam Draper, and Noemie Dion Ouellet (filed Aug. 25, 2011), “Power Plant and Method of Operation” to Predrag Popovic (filed Aug. 25, 2011), “Power Plant and Method of Operation” to Sam Draper and Kenneth Kohl (filed Aug. 25, 2011), “Power Plant and Method of Operation” to Sam Draper (filed Aug. 25, 2011), “Power Plant and Method of Operation” to Sam Draper (filed Aug. 25, 2011), “Power Plant and Method of Operation” to Lisa Wichmann (filed Aug. 25, 2011), and “Power Plant and Control Method” to Karl Dean Minto (filed Aug. 25, 2011), the disclosures of which are incorporated by reference herein.

It should be apparent that the foregoing relates only to the preferred embodiments of the present invention and that numerous changes and modifications may be made herein without departing from the spirit and the scope of the invention as defined by the following claims and equivalents thereof.