What is the purpose of installing water spray cooling device in low pressure cylinder of steam turbine?

When the steam turbine is started, no-load and low-load, the steam flow is too small to take away the heat generated by the blast friction in the low-pressure cylinder, so the exhaust temperature rises and the exhaust cylinder temperature also rises.

The low pressure cylinder closing structure makes the expansion of steam turbine complicated, and it is difficult to control the differential expansion in operation. Moreover, the high pressure cylinder of ultra-supercritical steam turbine needs to be made of austenitic alloy steel, and the medium and low pressure steel does not need it. In order to save the amount of expensive austenitic alloy steel, ultra-supercritical steam turbines generally adopt cylinder structure.

Extended data:

The shell of the steam turbine is used to separate the flow passage of the steam turbine from the atmosphere, forming a closed steam chamber to ensure that the steam completes the energy conversion process inside the steam turbine. Nozzle chamber, diaphragm, diaphragm sleeve and other components are installed in the cylinder. The outside of the cylinder is connected with steam inlet, exhaust and extraction pipes.

Generally, the high-pressure section of the cylinder adopts alloy steel or carbon steel casting structure, and the low-pressure section can adopt casting structure or welded structure formed by welding simple castings, section steel and steel plates according to the requirements of capacity and structure.

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