The invention provides a CO.sub.2 turbine power generation system that can be easily prevented from reaching an overspeed condition. A CO.sub.2 turbine power generation system of an embodiment includes a CO.sub.2 medium shutoff valve installed in a medium flow path between a regenerative heat exchanger and a combustor. When load rejection is to be performed, the CO.sub.2 medium shutoff valve closes to shut off the supply of the medium from the regenerative heat exchanger to the combustor.

The invention provides a CO.sub.2 turbine power generation system that can be easily prevented from reaching an overspeed condition. A CO.sub.2 turbine power generation system of an embodiment includes a CO.sub.2 medium shutoff valve installed in a medium flow path between a regenerative heat exchanger and a combustor. When load rejection is to be performed, the CO.sub.2 medium shutoff valve closes to shut off the supply of the medium from the regenerative heat exchanger to the combustor.

The present disclosure relates to systems and methods useful for power production. In particular, a power production cycle utilizing CO.sub.2 as a working fluid may be configured for simultaneous hydrogen production. Beneficially, substantially all carbon arising from combustion in power production and hydrogen production is captured in the form of carbon dioxide. Further, produced hydrogen (optionally mixed with nitrogen received from an air separation unit) can be input as fuel in a gas turbine combined cycle unit for additional power production therein without any atmospheric CO.sub.2 discharge.

The present disclosure relates to systems and methods useful for power production. In particular, a power production cycle utilizing CO.sub.2 as a working fluid may be configured for simultaneous hydrogen production. Beneficially, substantially all carbon arising from combustion in power production and hydrogen production is captured in the form of carbon dioxide. Further, produced hydrogen (optionally mixed with nitrogen received from an air separation unit) can be input as fuel in a gas turbine combined cycle unit for additional power production therein without any atmospheric CO.sub.2 discharge.

The present disclosure provides systems and methods wherein power production can be achieved with combustion of a fuel utilizing flameless combustion. A fuel may be combusted in a combustor/turbine in a substantially flameless operation to produce a combustion product stream that can be expanded for power generation. After expansion, the output stream can be treated to generate a recycle CO.sub.2 stream into which an oxidant can be input. The recycle CO.sub.2 stream including the oxidant can be injected into the combustor/turbine to effect combustion in a substantially flameless state. Various control schemes can be implemented to automatically control the concentration of oxygen present in the recycle CO.sub.2 stream that is injected into the combustor/turbine in order to achieve and/or maintain substantially flameless combustion.

The present disclosure provides systems and methods wherein power production can be achieved with combustion of a fuel utilizing flameless combustion. A fuel may be combusted in a combustor/turbine in a substantially flameless operation to produce a combustion product stream that can be expanded for power generation. After expansion, the output stream can be treated to generate a recycle CO.sub.2 stream into which an oxidant can be input. The recycle CO.sub.2 stream including the oxidant can be injected into the combustor/turbine to effect combustion in a substantially flameless state. Various control schemes can be implemented to automatically control the concentration of oxygen present in the recycle CO.sub.2 stream that is injected into the combustor/turbine in order to achieve and/or maintain substantially flameless combustion.

The embodiment relates to an energy conversion system having: a Solid Oxide Fuel Cell (SOFC) unit (A) having an anode and a cathode side, for receiving a fuel (1) and a steam of oxidant (4) and for converting a fraction of chemical power of the fuel (1) into electric power; a combustor unit (B) to receive unconverted fuel (5) and unconverted oxidant (6), configured for converting the unconverted fuel (5) and the unconverted oxidant (6) into product gas (10); an expander unit (C) to receive the product gas (10) and configured for expanding said product gas (10) into flue gas (12); a cooler unit (E) in thermal relationship with a heat sink (27) and configured for cooling said flue gas (12); a separator (F) for removing condensed species (15) from the cooled gas (14) exiting the cooler unit (E); and a first compression unit (K) for increasing the pressure of said oxidant (26, 4, 8) to a value suitable for the SOFC unit (A) and the combustor unit (B).

The present invention relates to systems and methods for controlling a power production plant and optionally providing a one or more product streams for an end use thereof. Control of a power production plant specifically can include executing one or more functions effective for adjusting a heat profile of a heat exchange unit (HEU) operating with a plurality of streams passing therethrough. This can include implementing a control function that alters a flow of one or more of the plurality of streams by adding flow to or withdrawing flow one or more of the plurality of streams at an intermediate temperature range within the HEU at a point that is positioned between a first end and a second end of the HEU.

The present invention relates to systems and methods for controlling a power production plant and optionally providing a one or more product streams for an end use thereof. Control of a power production plant specifically can include executing one or more functions effective for adjusting a heat profile of a heat exchange unit (HEU) operating with a plurality of streams passing therethrough. This can include implementing a control function that alters a flow of one or more of the plurality of streams by adding flow to or withdrawing flow one or more of the plurality of streams at an intermediate temperature range within the HEU at a point that is positioned between a first end and a second end of the HEU.

The present disclosure relates to systems and methods that are useful in control of one or more aspects of a power production plant. More particularly, the disclosure relates to power production plants, methods of starting power production plants, and methods of generating power with a power production plant wherein one or more control paths are utilized for automated control of at least one action. The present disclosure more particularly relates to power production plants, control systems for power production plants, and methods for startup of a power production plant.