Compound feed pump turbine for thermal power plant and thermodynamic system

Abstract

The invention relates to a compound feed pump turbine for a terminal power plant and a thermodynamic system, in particular to a feed pump compound turbine driving system used for the thermodynamic power plant. The feed pump compound turbine driving system comprises a steam extracting and condensing type small turbine, an extracting and condensing small machine low-pressure heater 6', an extracting and condensing small machine low-pressure heater 7' and a condensing water flow adjusting valve. The output end of the steam extracting and condensing type small turbine is connected with a boiler feed pump. The extracting and condensing small machine low-pressure heater 6' and the extracting and condensing small machine low-pressure heater 7' are connected with the steam extracting and condensing type small turbine through steam extracting pipelines. The extracting and condensing small machine low-pressure heater 6' is connected with the extracting and condensing small machine low-pressure heater 7' and the condensing water flow adjusting valve in series through a condensed water pipeline, and condensing pipelines formed through series connection are connected to a condensing pipeline which is formed through series connection of a main machine low-pressure heater 6, a main machine low-pressure heater 7 and a main machine condensed water flow adjusting valve in parallel. The problems of a feed pump configuration manner and slightly high energy consumption which trouble a direct air-cooling unit at present are solved.

Description

technical field [0001] The invention relates to a steam turbine driven by a boiler feedwater pump and a heat recovery system in a thermal power plant, in particular to a composite feedwater pump steam turbine and a thermal system used in a thermal power plant. Background technique [0002] The steam extraction and feed water pump thermal system of the main steam turbine (referred to as the main engine) in the direct air cooling unit is as follows: figure 1 As shown, the main steam from the boiler enters the high-pressure cylinder HP of the main engine to do work and then returns to the boiler BR for reheating, and the reheated steam from the boiler BR enters the medium-pressure cylinder IP of the main engine to do work and is discharged into the low-pressure cylinder LP of the main engine to continue to do work. Finally, it is discharged into the exhaust device E and condensed to form condensed water. The condensed water is passed through the low-pressure heaters No. 7, 6, a...

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Problems solved by technology

If the direct air-cooled unit adopts the method that the exhaust steam of the pure condensing unit is directly discharged into the exhaust device of the main engine, it is necessary to further consider the sudden drop of back pressure caused by strong winds in summer, and the design margin of the pure condensing unit needs to be increased. The margins are superimposed layer by layer, resulting in low operating efficiency of the pure condensing machine

[0005] In addition, as the unit develops towards higher parameters, the reheat steam temperature of the ultra-supercritical unit has reached 620°C, and is developing towards 700°C. The degree of superheat continues to increase. Even with the installation of an external steam cooler, the high-quality energy of the 3-stage extraction steam cannot be used more reasonably, which affects the efficiency of the heat recovery cycle of the unit

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