Advantages and uses of power station valves
Follow times: Release time: 2018-03-26
The gate valve for welding connection of the power station valve is suitable for the pipelines of various systems of petroleum, chemical, hydraulic and thermal power stations with a nominal pressure of PN16.0-32.0MPa and an operating temperature ≤540 ° C (among which P57170V operating temperature is 570 ℃) Connect the pipeline medium. Applicable media: water, oil, steam, acid media, etc. The operation modes are: manual, gear transmission, electric, etc.
The main valve of the turbine is installed between the pressure pipe and the volute. The main valve has only two working positions, fully open and fully closed. It does not adjust the water inlet flow of the turbine. Its functions include the following aspects.
1. Provide safe working conditions for unit maintenance. When the power station adopts a combined or group water supply method in which one pressure pipe supplies water to two or more units, one of the units can be overhauled and its main valve can be closed to form safe work without affecting the operation of other units. condition.
2. Reduce the water leakage of the unit when the machine is stopped, and shorten the time required for startup when the machine is turned on. The turbine's water-guiding mechanism is often not tightly closed, and there is a large amount of water leakage after shutdown. This not only wastes water energy, but also causes cavitation damage in the gap due to water leakage. According to statistics, the leakage of the general guide vane is about 2% -5% of the maximum flow of the turbine, and the serious can reach 8%. Even small units with high heads cannot stop due to excessive leakage. When the unit is shut down for a long time, closing its water inlet valve can greatly reduce water leakage. When the unit is shut down for a short time, the inlet gate of the pressure pipeline is generally not closed. Because this will cause the water in the pressure pipe to be drained due to water leakage at the end of the pipe, the pressure pipe needs to be refilled before restarting, which prolongs the startup time of the unit and prevents the unit from maintaining standby status at any time. And quick action. Closing the water inlet valve can both reduce water leakage and shorten the time required to restart the unit. For medium and high head power stations with longer pressure pipes, this effect of the turbine main valve is even more pronounced.
3. Prevent the flight accident of the unit from expanding. When the unit or the governor system fails, the turbine failure to shut down in time may cause a unit flight accident. At this time, the speed signaler should automatically issue a command to urgently close the turbine main valve to quickly shut off the water flow to prevent the unit from escaping and prevent the accident from expanding. If the main valve of the turbine is not set, the inlet gate of the pressure pipeline should be closed quickly, but because the pressure tube is emptied, the flight time of the unit will be longer.