A system includes a fuel control system configured to control a fuel flow to one or more combustors and an oxidant control system configured to control an oxidant flow to each combustor of the one or more combustors, wherein the oxidant flow is configured to at least partially react with the fuel flow within the one or more combustors to form an exhaust gas flow. The system also includes an exhaust gas system configured to direct a recirculation flow of the exhaust gas flow to each combustor of the one or more combustors; and a controller coupled to the fuel control system, the oxidant control system, and the exhaust gas system. The controller is configured to independently control a fuel-to-oxidant ratio and an exhaust gas-to-oxidant ratio. The FOR is the fuel flow divided by the oxidant flow, and the EGOR is the recirculation flow divided by the oxidant flow.

The present invention provides methods and system for power generation using a high efficiency combustor in combination with a CO.sub.2 circulating fluid. The methods and systems advantageously can make use of a low pressure ratio power turbine and an economizer heat exchanger in specific embodiments. Additional low grade heat from an external source can be used to provide part of an amount of heat needed for heating the recycle CO.sub.2 circulating fluid. Fuel derived CO.sub.2 can be captured and delivered at pipeline pressure. Other impurities can be captured.

A gas separation process for treating exhaust gases from combustion processes. The invention involves routing a first portion of the exhaust stream to a carbon dioxide capture step, while simultaneously flowing a second portion of the exhaust gas stream across the feed side of a membrane, flowing a sweep gas stream, usually air, across the permeate side, then passing the permeate/sweep gas back to the combustor.

The present techniques are directed to a system and method for generating power and recovering methane from methane hydrates. The system includes a low emissions power plant configured to generate power, wherein an exhaust gas from the low emissions power plant provides a gas mixture including nitrogen and carbon dioxide. The system also includes a methane recovery system configured to recover methane from methane hydrates by injecting the nitrogen and the carbon dioxide from the gas mixture into the methane hydrates.

A supercritical working fluid closed cycle heat engine includes, in fluid flow series: a heat source heat exchanger configured to raise the temperature of a working fluid; an expander configured to extract work from the working fluid; a condenser configured to exchange heat between the working fluid and the cooling medium;
and a separator configured to separate liquid phase working fluid from gaseous phase working fluid and deliver gaseous phase working fluid to a gaseous compressor and liquid phase working fluid to a fixed displacement liquid pump, the compressor and pump being arranged in parallel. Each of the compressor and fixed displacement pump are configured to return fluid to the heat source heat exchanger. The compressor comprises a variable inlet guide vane and a variable outlet diffuser vane.

A supercritical working fluid closed cycle heat engine includes, in fluid flow series: a heat source heat exchanger configured to raise the temperature of a working fluid; an expander configured to extract work from the working fluid; a condenser configured to exchange heat between the working fluid and the cooling medium; and a separator configured to separate liquid phase working fluid from gaseous phase working fluid and deliver gaseous phase working fluid to a gaseous compressor and liquid phase working fluid to a fixed displacement liquid pump, the compressor and pump being arranged in parallel. Each of the compressor and fixed displacement pump are configured to return fluid to the heat source heat exchanger. The compressor comprises a variable inlet guide vane and a variable outlet diffuser vane.

A gas separation process for treating exhaust gases from combustion processes. The invention involves routing a first portion of the exhaust stream to a carbon dioxide capture step, while simultaneously flowing a second portion of the exhaust gas stream across the feed side of a membrane, flowing a sweep gas stream, usually air, across the permeate side, then passing the permeate/sweep gas back to the combustor.

The gas turbine system comprises a gas turbine engine, a first fuel line adapted to feed fuel to the gas turbine engine, a heat recovery steam generator adapted to receive flue gas exhausted from the gas turbine engine, and a second fuel line adapted to feed fuel to a post-burner of the heat recovery steam generator. A carbon dioxide capture unit is fluidly coupled to a stack of the heat recovery steam generator. A recycling line recycles flue gas from the stack of the heat recovery steam generator to the post-burner in the heat recovery steam generator. A carbon dioxide return line recycles a gaseous stream containing carbon dioxide from the carbon dioxide capture unit towards the gas turbine engine or the post-burner. Disclosed herein is also a power generation method with improved carbon dioxide capture.

Hydrogen-fueled gas turbine power system comprising a compressor (22), a combustor (24) and a turbine (26) as well as a fuel supply device (10). The fuel supply device (10) has the form of a hydrogen gas producing reactor system with at least one reactor (12) based on sorption enhanced steam methane reforming (SE-SMR) and/or sorption enhanced water gas shift (SE-WGS) of syngas. The reactor (12) is connected in a closed loop with a regenerator (14) for circulating and regenerating a CO.sub.2 absorber between the reactor (12) and the regenerator (14). Additionally, there is a closed heat exchange loop (21) between the regenerator (14) of the hydrogen gas producing reactor system (10) and the downstream end of the combustor (24) or the upstream end of the turbine (26). A method of its use is also contemplated.

In various aspects, a method for producing electricity by operating two or more turbines in series is provided. The method can include introducing, at least part of, the exhaust from an upstream turbine into a combustion chamber of a downstream turbine. In one aspect, exhaust from the upstream turbine is introduced into the downstream turbine's combustion chamber via the downstream turbine's compression chamber.