What is the function of a steam turbine shaft seal?
1 Answers
The functions of a steam turbine shaft seal are as follows: The shaft seal at the low-pressure end of a condensing steam turbine prevents external air from leaking into the cylinder, which would otherwise disrupt the vacuum in the condenser, increase the exhaust pressure of the turbine, and reduce the unit's economic efficiency. To recover the steam leaking from the high-pressure end and prevent external air from entering through the low-pressure end, steam turbines are equipped with a sealing system. Its working principle is as follows: 1. The high-pressure end shaft seal is divided into several segments, with a certain gap left between each segment. The leaking steam from these gaps is directed to different locations based on its pressure for utilization, thereby improving the unit's economic efficiency. 2. Steam flows from the high-pressure end shaft seal through pipelines; part of the steam passes through some sealing segments and enters the low-pressure cylinder, while the other part flows outward along the shaft seal clearance and is eventually discharged into the atmosphere through a signal pipe. 3. During the startup and shutdown of the steam turbine, if there is no steam at the high-pressure end shaft seal, reduced and depressurized fresh steam should be introduced and simultaneously sent to both the high and low-pressure end shaft seals.
