A method for operating a turbine unit having at least two partial turbines, wherein a steam volumetric flow is conducted by a steam transfer device from the partial turbine arranged upstream to a partial turbine arranged downstream, which is connected after the partial turbine arranged upstream, wherein a pressure level within the steam transfer device is manipulated in accordance with a load range in which the turbine unit is operated, in such a way that the exhaust steam of the partial turbine arranged upstream remains superheated in the event of operation of the turbine unit in a partial-load range below the IGV point and/or in the event of a quick increase in the partial load.

Aspects of the invention disclosed herein generally provide a heat engine system, a turbopump system, and methods for lubricating a turbopump while generating energy. The systems and methods provide proper lubrication and cooling to turbomachinery components by controlling pressures applied to a thrust bearing in the turbopump. The applied pressure on the thrust bearing may be controlled by a turbopump back-pressure regulator valve adjusted to maintain proper pressures within bearing pockets disposed on two opposing surfaces of the thrust bearing. Pocket pressure ratios, such as a turbine-side pocket pressure ratio (P1) and a pump-side pocket pressure ratio (P2), may be monitored and adjusted by a process control system. In order to prevent damage to the thrust bearing, the systems and methods may utilize advanced control theory of sliding mode, the multi-variables of the pocket pressure ratios P1 and P2, and regulating the bearing fluid to maintain a supercritical state.

A method is provided for converting heat from a heat source to mechanical energy. The method comprises heating a working fluid using heat supplied from the heat source; and expanding the heated working fluid to lower pressure of the working fluid and generating mechanical energy as the pressure of the working fluid is lowered. The method is characterized by using a working fluid comprising (2E)-1,1,1,4,5,5,5-heptafluoro-4-(trifluoromethyl)pent-2-ene (HFO-153-10mzzy). Also provided is a power cycle apparatus. The apparatus is characterized by containing a working fluid comprising HFO-153-10mzzy.

A method is provided for converting heat from a heat source to mechanical energy. The method comprises heating a working fluid using heat supplied from the heat source; and expanding the heated working fluid to lower pressure of the working fluid and generating mechanical energy as the pressure of the working fluid is lowered. The method is characterized by using a working fluid comprising (2E)-1,1,1,4,5,5,5-heptafluoro-4-(trifluoromethyl)pent-2-ene (HFO-153-10mzzy). Also provided is a power cycle apparatus. The apparatus is characterized by containing a working fluid comprising HFO-153-10mzzy.

Disclosed is a Once-Through Steam Generator (OTSG) coil (52) and method, comprising a plurality of vertically arranged serpentine conduits (90) in a horizontal heat recovery steam generator (HRSG) that replaces a traditional natural circulation HP evaporator for producing super-critical steam. The OTSG comprises a lower equalization header system (130) that promotes system stability in multiple operating conditions. The equalization header allows a partial flow of fluid from the lower serpentine curved flow path (120) through an equalization conduit (125) into the equalization header (130) Disclosed also are: a flow restriction device in serpentine conduits; drainage structure from serpentine conduits through the equalization header, a drainage expansion section to accommodate stresses, and drainage bypass connections; and flow through serpentine conduits in upstream and downstream directions, mixed flow directions and longitudinally staggered directions.

Disclosed is a Once-Through Steam Generator (OTSG) coil (52) and method, comprising a plurality of vertically arranged serpentine conduits (90) in a horizontal heat recovery steam generator (HRSG) that replaces a traditional natural circulation HP evaporator for producing super-critical steam. The OTSG comprises a lower equalization header system (130) that promotes system stability in multiple operating conditions. The equalization header allows a partial flow of fluid from the lower serpentine curved flow path (120) through an equalization conduit (125) into the equalization header (130) Disclosed also are: a flow restriction device in serpentine conduits; drainage structure from serpentine conduits through the equalization header, a drainage expansion section to accommodate stresses, and drainage bypass connections; and flow through serpentine conduits in upstream and downstream directions, mixed flow directions and longitudinally staggered directions.

Power is produced by operating first and second nested cycles utilising CO.sub.2 as working fluid without mixing of working fluid between the nested cycles. The first cycle comprises a semi-open loop operating under low pressure conditions in which CO.sub.2 is sub-critical. The second cycle comprises a closed loop operating under higher pressure conditions in which CO.sub.2 is supercritical. The first cycle operates in a Brayton cycle including oxycombustion of hydrocarbons, preferably LNG, in a combustion chamber under low pressure conditions, expansion for power production to provide a first power source, cooling in a recuperator, compression, reheating by counter-current passage via the recuperator, and return of working fluid heated by the recuperator back to the combustion chamber. Water and excess CO.sub.2 resulting from the oxycombustion step are separated from the first cycle. The first cycle serves as a source of heat for the second cycle by gas/gas heat exchange in a gas/gas heat exchanger which results in cooling of the products of combustion and circulating working fluid in the first cycle and heating of working fluid in the second cycle. The second cycle is operated in a Brayton cycle including heating of working fluid in the second cycle by the gas/gas heat exchanger, expansion for power generation to provide a second power source, cooling in two-stages by first and second recuperator steps, compression, reheating by counter-current passage via the first recuperator step, and return of working fluid heated by the first recuperator step back to the gas/gas heat exchanger. Working fluid in the first cycle following the compression step is heated by working fluid in the second cycle by counter-current passage via the second recuperator step.

Power is produced by operating first and second nested cycles utilising CO.sub.2 as working fluid without mixing of working fluid between the nested cycles. The first cycle comprises a semi-open loop operating under low pressure conditions in which CO.sub.2 is sub-critical. The second cycle comprises a closed loop operating under higher pressure conditions in which CO.sub.2 is supercritical. The first cycle operates in a Brayton cycle including oxycombustion of hydrocarbons, preferably LNG, in a combustion chamber under low pressure conditions, expansion for power production to provide a first power source, cooling in a recuperator, compression, reheating by counter-current passage via the recuperator, and return of working fluid heated by the recuperator back to the combustion chamber. Water and excess CO.sub.2 resulting from the oxycombustion step are separated from the first cycle. The first cycle serves as a source of heat for the second cycle by gas/gas heat exchange in a gas/gas heat exchanger which results in cooling of the products of combustion and circulating working fluid in the first cycle and heating of working fluid in the second cycle. The second cycle is operated in a Brayton cycle including heating of working fluid in the second cycle by the gas/gas heat exchanger, expansion for power generation to provide a second power source, cooling in two-stages by first and second recuperator steps, compression, reheating by counter-current passage via the first recuperator step, and return of working fluid heated by the first recuperator step back to the gas/gas heat exchanger. Working fluid in the first cycle following the compression step is heated by working fluid in the second cycle by counter-current passage via the second recuperator step.

Various technologies pertaining to tuning composition of a fluid mixture in a supercritical Brayton cycle power generation system are described herein. Compounds, such as Alkanes, are selectively added or removed from an operating fluid of the supercritical Brayton cycle power generation system to cause the critical temperature of the fluid to move up or down, depending upon environmental conditions. As efficiency of the supercritical Brayton cycle power generation system is substantially optimized when heat is rejected near the critical temperature of the fluid, dynamically modifying the critical temperature of the fluid based upon sensed environmental conditions improves efficiency of such a system.

Various technologies pertaining to tuning composition of a fluid mixture in a supercritical Brayton cycle power generation system are described herein. Compounds, such as Alkanes, are selectively added or removed from an operating fluid of the supercritical Brayton cycle power generation system to cause the critical temperature of the fluid to move up or down, depending upon environmental conditions. As efficiency of the supercritical Brayton cycle power generation system is substantially optimized when heat is rejected near the critical temperature of the fluid, dynamically modifying the critical temperature of the fluid based upon sensed environmental conditions improves efficiency of such a system.