What is the purpose of the cross-line from the shaft seal steam of the condensing steam turbine to the working steam outlet of the turbine (with a valve on it)?
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What is the purpose of the cross-line from the shaft seal steam of the condensing steam turbine to the working steam outlet of the turbine (with a valve on it)? Thank you all, experts. This issue has been bothering me for a long time. Also, at the high-pressure end, around the location of the steam seal, there is a very thin wire connected to the shaft seal steam. Is this wire a self-sealing wire? (I once heard it called a clearance bypass wire)
This valve opens before sealing steam is introduced, and closes once the sealing steam is in order. Its function is to effectively warm the seal steam pipeline from behind the self-acting control valve to the turbine shaft seal, thereby preventing condensation water from accumulating in the pipeline and affecting the sealing performance of the shaft seal.
Thank you to the person in floor 2. Does this expert know what the purpose of the wire running from the high-pressure side to the shaft seal is? I’m sincerely seeking advice!
The front steam seal of the turbine is under positive pressure, and there are three paths for the leakage steam: 1) it goes to the seal steam pipeline, where it merges with the externally supplied seal steam (through a device similar to a mixer) to supply seal steam to the rear steam seal (which is under negative pressure). 2. A steam vent pipe at the top of the front steam seal discharges steam to the atmosphere. 3. The shaft end vents to the atmosphere. There are two pipelines leading to the steam seal circuit (mixer); they are connected to chamber II and chamber I of the front seal, respectively. The thicker pipeline is connected to chamber II, while the thinner one is connected to chamber I – and it is this thinner pipeline that you mentioned. Both pipelines serve as vent pipes for the front seal. You can understand this by looking at the structure of the front and rear shaft seals in the steam turbine.
:handshake:handshake I’ve seen it now!
In addition to facilitating the drainage of warm gas from the sealing system, this thin tube allows for pressure relief when abnormal conditions cause the shaft seal steam pressure to rise. However, following the principle of self-sealing control, it would be better to install a control valve on this tube as well; the sealing gas pressure transmitter can be used to generate control signals – air is supplied from the outside when the pressure is low, and pressure is relieved to the surface cooler when it is high. As for that pipeline for the high-pressure shaft seal, its function should be as you mentioned.
That makes sense; in fact, some shaft seal self-sealing systems used in the power industry’s condensing steam turbines are equipped with relief valves that provide automatic pressure release； Since the air leakage at the high-pressure side of industrial steam turbines is relatively low, the sealing steam at the low-pressure side mainly comes from supplementary sealing steam. Additionally, the steam pipeline for sealing leaks is equipped with a drain connection to an expansion tank, which also helps to relieve pressure; therefore, the valve leading to the surface cooler (or air cooler) is merely a manual valve.
The line that connects the shaft seal steam to the exhaust steam and is equipped with a hand valve – I just checked in the Hangqi manual; it’s called the shaft seal vent pipe. The wire at the high-pressure end is indeed the exhaust gas from chamber 2. But to which chamber is the shaft seal steam at high pressure sent?
Dear expert, please send me a copy of this instruction manual. Thank you! 617773118@qq.com