Turbine Gland Seal Steam Control Valves

[valvepuke]

I would appreciate a quick tutorial on the functions of the control valves utilized for turbine gland seal steam control. These three valves are generally designated as: Boiler supply valve; cold reheat supply valve, and the spillover valve. I am particularly interested in the operation scenarios for each of the valves as the turbine is brought on line to full load operation.

Also, in a few words, how does a gland seal work?

Any power plant valve scholars out there? I await anxiously your reply.

Valvepuke

 

[rmw]

Boiler supply steam is used until there is sufficient pressure in the cold reheat circuit to supply the gland sealing steam.

I failed the gland sealing system test at my Large Steam Turbine Field Engineering training, so I'll have to go look at my manual to answer the rest of your questions.

Gland sealing steam puts a pressure between the turbine internal pressure when it is less than atmospheric and the atmosphere so that air is prevented from entering the gland and the leakage is from the gland to the atmosphere and the gland into the turbine. That way what leaks into the turbine is gland sealing steam and not air.

I always have to look back for the circiut for positive pressure turbine shells.

rmw

 

[JimCasey]

Leslie Controls used to publish a "Power Industry Guide" that had schematics and typical application specs for all the traditionally challenging valves in a power plant. It is not listed on their website now, and the guy that wrote it went to a competitor. You could still ask if they have a copy.

Valtek released their "Power Industry Guidebook" last year and it is detailed and elaborate, but it does not specifically address Gland Seal. Still, you could drop a dime and call their power industry applications specialist.

 

[valvepuke]

It seems that this question concerning gland seal steam valves is not getting much response from the members' knowledge base. Perhaps someone knows about a text or handbook that might address this issue.

To Jim Casey: I have the Leslie application guides from way back and they do not go into much detail on this application. They touch only on the supply valve and not the others. I am trying to educate myself on this application because it is an application that is influenced almost as much by how the valves operate as it is by the pressure/temp/flow of the application. Many older turbines are ready for replacement of these valves. Just want to be up on what is best to replace them with out of the newer valve products.