A coal-fired power generation system and a supercritical CO.sub.2 cycle system thereof are provided. The supercritical CO.sub.2 cycle system includes a compressor unit and a turbine unit. The turbine unit includes a preceding stage heater, a preceding stage turbine, a last stage heater and a last stage turbine successively connected in series. An exhaust port of at least one of compressors in the compressor unit is in communication with the turbine unit through a split flow pipe, and a communication position between the split flow pipe and the turbine unit is located downstream of a suction port of the preceding stage turbine. An auxiliary regenerator and an auxiliary heater are provided at the split flow pipe, and the auxiliary regenerator is located upstream of the auxiliary heater.

The single-working-medium vapor combined cycle is provided in this invitation and belongs to the field of energy and power technology. A single-working-medium vapor combined cycle method consisting of eleven processes which are conducted with M.sub.1 kg of working medium and M.sub.2 kg of working medium separately or jointly: performing a pressurization process to set a state (1) to (2) of the M.sub.1 kg of working medium, performing a heat-absorption and vaporization process to set a state (2) to (3) of the M.sub.1 kg of working medium, performing a depressurization process to set a state (3) to (4) of the M.sub.1 kg of working medium, performing a pressurization process to set a state (1) to (e) of the H kg of working medium, performing a heat-absorption process to set a state (e) to (7) of the H kg of working medium, performing a pressurization process to set a state (7) to (4) of the M.sub.2 kg of working medium, performing a heat-absorption process to set a state (4) to (5) of the (M.sub.1+M.sub.2) kg of working medium, performing a depressurization process to set a state (5) to (6) of the (M.sub.1+M.sub.2) kg of working medium, performing a mixed heat-releasing process to set a state (6) to (7) of the (M.sub.1+M.sub.2) kg of working medium and H kg of working medium, performing a depressurization process to set a state (7) to (8) of the (M.sub.1+H) kg of working medium, performing a heat-releasing and condensation process to set a state (8) to (1) of the (M.sub.1+H) kg of working medium.

The single-working-medium vapor combined cycle is provided in this invitation and belongs to the field of energy and power technology. A single-working-medium vapor combined cycle method consisting of eleven processes which are conducted with M.sub.1 kg of working medium and M.sub.2 kg of working medium separately or jointly: performing a pressurization process to set a state (1) to (2) of the M.sub.1 kg of working medium, performing a heat-absorption and vaporization process to set a state (2) to (3) of the M.sub.1 kg of working medium, performing a depressurization process to set a state (3) to (4) of the M.sub.1 kg of working medium, performing a pressurization process to set a state (1) to (e) of the H kg of working medium, performing a heat-absorption process to set a state (e) to (7) of the H kg of working medium, performing a pressurization process to set a state (7) to (4) of the M.sub.2 kg of working medium, performing a heat-absorption process to set a state (4) to (5) of the (M.sub.1+M.sub.2) kg of working medium, performing a depressurization process to set a state (5) to (6) of the (M.sub.1+M.sub.2) kg of working medium, performing a mixed heat-releasing process to set a state (6) to (7) of the (M.sub.1+M.sub.2) kg of working medium and H kg of working medium, performing a depressurization process to set a state (7) to (8) of the (M.sub.1+H) kg of working medium, performing a heat-releasing and condensation process to set a state (8) to (1) of the (M.sub.1+H) kg of working medium.

A steam network assembly for a plant including an ammonia-producing unit and a urea-producing unit, including a high-pressure steam line, two medium-pressure steam lines and first and second turbines supplied with high-pressure steam by the high-pressure steam line; wherein the first turbine is a condensing-type turbine with extraction into one of the two medium-pressure steam lines, and is configured to deliver power to a syngas compressor in the ammonia-producing unit of the plant, and the second turbine is a counter-pressure type turbine with extraction connected to the two medium-pressure steam lines and is configured to deliver power to a CO.sub.2 compressor in the urea-producing unit of the plant. A method to distribute high-pressure steam in a steam network assembly for a plant including an ammonia-producing unit and a urea-producing unit and a method to revamp the steam network assembly for a plant including an ammonia-producing unit and a urea-producing unit.

A steam network assembly for a plant including an ammonia-producing unit and a urea-producing unit, including a high-pressure steam line, two medium-pressure steam lines and first and second turbines supplied with high-pressure steam by the high-pressure steam line; wherein the first turbine is a condensing-type turbine with extraction into one of the two medium-pressure steam lines, and is configured to deliver power to a syngas compressor in the ammonia-producing unit of the plant, and the second turbine is a counter-pressure type turbine with extraction connected to the two medium-pressure steam lines and is configured to deliver power to a CO.sub.2 compressor in the urea-producing unit of the plant. A method to distribute high-pressure steam in a steam network assembly for a plant including an ammonia-producing unit and a urea-producing unit and a method to revamp the steam network assembly for a plant including an ammonia-producing unit and a urea-producing unit.

A steam network assembly for a plant including an ammonia-producing unit and a urea-producing unit, including a high-pressure steam line, two medium-pressure steam lines and first and second turbines supplied with high-pressure steam by the high-pressure steam line; wherein the first turbine is a condensing-type turbine with extraction into one of the two medium-pressure steam lines, and is configured to deliver power to a syngas compressor in the ammonia-producing unit of the plant, and the second turbine is a counter-pressure type turbine with extraction connected to the two medium-pressure steam lines and is configured to deliver power to a CO.sub.2 compressor in the urea-producing unit of the plant. A method to distribute high-pressure steam in a steam network assembly for a plant including an ammonia-producing unit and a urea-producing unit and a method to revamp the steam network assembly for a plant including an ammonia-producing unit and a urea-producing unit.

A coal-fired power generation system and a supercritical CO.sub.2 cycle system thereof are provided. The supercritical CO.sub.2 cycle system includes a compressor unit and a turbine unit. The turbine unit includes a preceding stage heater, a preceding stage turbine, a last stage heater and a last stage turbine successively connected in series. An exhaust port of at least one of compressors in the compressor unit is in communication with the turbine unit through a split flow pipe, and a communication position between the split flow pipe and the turbine unit is located downstream of a suction port of the preceding stage turbine. An auxiliary regenerator and an auxiliary heater are provided at the split flow pipe, and the auxiliary regenerator is located upstream of the auxiliary heater.

An improved heat engine employing a dual-component working fluid and configured to generate internal heat from one component of the working fluid that heats the other component through the physical contact between them such that together with the addition of external heat, the engine advantageously yields enhanced work extraction efficiency through separate, parallel expansion of each of the working fluids.

A dual-cycle heat engine employing a first cycling working fluid and a second cycling working fluid whose cycles overlap when fused into a combined working stream so as to preserve compression heat generated during compression of the first working fluid thereby yielding enhanced work extraction when complying with additional thermodynamic requirements.

A process and system of extracting useful work or electricity from a thermal source, wherein heat energy from the thermal source is used in the form of a heated collection fluid; a first side of a heat exchanger is filled with a liquid or supercritical working fluid; fluid flow out of the first side of the heat exchanger is closed such that a fixed volume of the working fluid is maintained in the first side; the heated collection fluid flowed through a second side of the heat exchanger that is adjacent to the first side to affect a transfer of heat from the heated collection fluid to the fixed volume of the working fluid to raise its temperature and pressure; the pressurized working fluid is released from the first side of the heat exchanger upon the working fluid reaching a threshold state; a flow of the pressurized working fluid is directed to an expander capable of converting the kinetic energy of the pressurized working fluid into useful work or electricity; and the foregoing steps are repeated. A plurality of such operably coupled heat exchangers may be used in a manner such that the timing of the pressurized working fluid from each heat exchanger to the expander is offset.