System and method for supplying motive power for auxiliary machinery of thermal power plant

Abstract

The invention discloses a system and a method for supplying motive power for auxiliary machinery of a thermal power plant. The system comprises a screw expansion power machine, a speed reducer, a load supplementing motor, a low-pressure heater, a deaerator and an induced draft fan. The method for supplying the motive power for the auxiliary machinery includes driving the screw expansion power machine by extracted steam of a low-pressure cylinder of a steam turbine of the thermal power plant or other low-grade steam (with the steam pressure ranging from 0.3MPa to 1.0MPa and the steam temperature ranging from 200 DEG C to 300 DEG C); replacing the motor by the motive power generated by the screw expansion power machine to directly drive the auxiliary machinery including the induced draft fan and the like of the thermal power plant; and sufficiently utilizing the low-grade steam of the thermal power plant to achieve the purpose of reducing power consumption of the thermal power plant. By the system and the method, the low-grade steam can be sufficiently utilized, and the system and the method have the advantages of flexible configuration of the system, convenience in operation, high energy gradient utilization efficiency and the like.

Description

technical field [0001] The invention relates to a supply system and method using a screw expansion power machine as the driving force of auxiliary machines such as induced draft fans in thermal power plants, and belongs to the technical field of waste heat recovery in thermal power plants. Background technique [0002] In a traditional thermal power plant, the high-temperature and high-pressure steam produced by the boiler passes through the steam turbine and then the exhaust steam is recirculated through the condenser, during which a large amount of waste heat is taken away by the circulating water vapor, resulting in a huge loss of energy and a serious waste of energy. At present, the energy-saving and environmental protection standards of my country's power industry are increasing day by day. However, in my country's thermal power plants, the pumps and fans of small and medium-sized units still generally have the problem of low efficiency. According to statistics, the ave...

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Problems solved by technology

[0004] Patent CN101899999A The small steam turbine system of a power plant and the thermal cycle system of a power plant containing the system discloses a system that utilizes a small steam turbine to generate electricity for an auxiliary machine of a thermal power plant and drives a high-power auxiliary machine, but the small steam turbine still has relatively high requirements for steam quality , the power plant steam cannot be completely and fully applied, resulting in a certain degree of waste

In addition, the model of the small steam turbine is fixed, and it is impossible to make corresponding adjustments after the working conditions change, and the adaptability is weak

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