How is the steam for turbine sealing established?

It is necessary to set this up before starting the machine, especially for condensing steam turbines. In the case of single-stage condensing steam turbines, the steam required for the steam seal is supplied by an external low-pressure steam network; whereas in multi-stage condensing steam turbines, the steam leakage from the high-pressure end, along with some steam drawn from between the stages, is used to control the pressure of the steam seal through self-acting control valves. Generally, during startup, the steam leakage from the high-pressure end is the source of steam used, and it is sufficient to increase the bypass opening of the self-acting control valves before starting the machine. In back-pressure steam turbines, the shaft seals have steam leaks at both ends that are above atmospheric pressure; these leaks are removed using ejectors to prevent steam from entering the bearings.

According to you, it should be set up before driving, but the seal steam comes from the high-pressure side – how can there be steam before the vehicle even starts? Where does the sealed steam go then?

Introduce steam first. The steam from driving should condense in the steam condenser!

Many preparations are needed before starting the machine. During warm-up, it is sufficient to open the bypass for the self-acting control valve of the seal steam. Of course, if it is felt that the negative pressure in the surface cooler decreases at the start of operation, to the point where no steam can be drawn in, it is possible to introduce low-pressure steam from an external steam network to supply the seal steam required for startup. Part of this seal steam leaks into the turbine exhaust side and is discharged into the surface cooler, while another part is drawn out by the seal steam extractor, condensed, and then discharged into the surface cooler as well.

Is a self-acting control valve a steam control valve located between the high-pressure side and the low-pressure side, through which steam is directed from the high-pressure side to the low-pressure side? Doesn’t the high-pressure side require sealed steam? You said that when driving, sealed steam is drawn from the high-pressure side; then is it also drawn from the high-pressure side under normal conditions? According to what you say, the sealing steam isn’t established before starting up; it is only generated at the moment of startup

Where does the sealing steam for a back-pressure turbine come from? It would be good to have a diagram with shaft seals

http://bbs.hcbbs.com/viewthread.php?tid=192580&highlight=%C3%DC%B7%E2%D5%F4%C6%FB Principle of sealed steam.

Before starting the machine, steam from the pipeline network should be used; after startup, it can be switched to steam leaking from the high-pressure side. As for the sealing steam, it can be condensed and removed using an extractor.