Self-adaptation shaft seal steam supply system

Abstract

The invention discloses a self-adaptation shaft seal steam supply system. The self-adaptation shaft seal steam supply system comprises a shaft seal main pipe, a valve rod air leakage adjusting steam supply branch, an overflow branch, a bypass pneumatic branch, a high-pressure cylinder shaft seal, a medium-pressure cylinder shaft seal and a low-pressure cylinder shaft seal; the inlet end of the shaft seal main pipe is provided with an auxiliary steam adjusting valve, the inlet end of the shaft seal main pipe communicates with the valve rod air leakage adjusting steam supply branch, the overflowbranch and the bypass pneumatic branch, and the outlet end of the shaft seal main pipe communicates with a rear shaft seal of the high-pressure cylinder shaft seal and a rear shaft seal of the medium-pressure cylinder shaft seal. According to the self-adaptation shaft seal steam supply system, when a unit is started, and after steam supply fails, the pressure difference of the two sides of a steam leakage check valve is increased, a differential pressure transmitter closes an adjusting valve of the valve rod air leakage adjusting steam supply branch, steam supply breaking off is prevented, inthe self-seal condition, the shaft seal steam supply pressure is increased, the differential pressure transmitter opens the adjusting valve of the valve rod air leakage adjusting steam supply branch,over-pressure of the shaft seal steam supply pipeline is prevented, through assisting of a steam adjusting valve, the steam temperature is adjusted, and safety and anti-failure capacity of the systemare improved.

Description

technical field [0001] The invention relates to the technical field of steam turbine equipment, in particular to an adaptive shaft seal steam supply system. Background technique [0002] Supercritical units usually adopt high and medium pressure split cylinder structure, especially the unit with medium pressure single split flow design, the rotor temperature difference at the front and rear shaft seals of high pressure cylinder and medium pressure cylinder is very different. The temperature of the rotor at the seal is relatively high, while the temperature of the rotor at the rear shaft seal of the high-pressure cylinder and the rear shaft seal of the medium-pressure cylinder is relatively low. Match the temperature of the rotor, otherwise it will affect the life of the rotor, and it is more likely that the large shaft will be locked. [0003] Power plant shaft seal steam supply usually uses auxiliary steam as the steam supply source for shaft seal, which can meet the steam...

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Problems solved by technology

[0003] Power plant shaft seal steam supply usually uses auxiliary steam as the steam supply source for shaft seal, which can meet the steam supply temperature requirements of the shaft seal after high-pressure cylinder and the rear shaft seal of medium-pressure cylinder in hot state and extremely hot state, but it cannot meet the steam supply temperature requirements before high-pressure cylinder. The high-temperature steam supply requirements for the shaft seal and the front shaft seal of the medium-pressure cylinder, when the conventional unit is started in a hot state or an extremely hot state, mainly rely on the steam supply from the main steam station or add an electric heater to the auxiliary steam station to provide high-temperature steam source. Although the system is simple, it can only provide one steam supply temperature for each steam seal of the high and medium pressure cylinders, and cannot perform independent temperature matching for the front shaft seals of the high and medium pressure cylinders and the rear shaft seals of the high and medium pressure cylinders. Conventional steam supply from the main steam station or adding an electric heater to the auxiliary steam station, the mismatch between the temperature of the steam supplied by the shaft seal and the temperature of the rotor is still prominent, and the problem of matching the temperature of the steam supplied by the rotor and the steam supplied by the shaft seal is not fundamentally solved

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