Steam turbine extraction valve

  • Thread starter Kanad Putatunda
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Kanad Putatunda

What type of valve is a "steam turbine extraction valve"? Which make actuators are generally used?

How does it function?
 
>What type of valve is a "steam turbine extraction valve"? Which make actuators are generally used? How does it function?<

It depends on the valve design the manufacturer used. I've seen spool valves and grid valves used for extraction valves (GE terms and design). Extraction valves are usually not required to be able to do 100% shutoff of steam flow (in fact some leak-by is often necessary for cooling). Which leads to another point, in certain steam turbines (GE for sure), the extraction valves OPEN to allow steam flow to continue down the remaining turbine stages and the valves CLOSE to force steam out the extraction lines.

Some actuators were pistons using steam, others used lube oil/control oil. I'm sure there are electro hydraulic actuators that use servo valves as well.

Actuators are controlled by various means including extraction pressure regulators, digital control systems, and more. GE made "3-arm" governors that control both extraction and inlet valves. To most people they are truly confusing, but I think they are fun to work on.
 
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