seal steam control valve 2

[abeltio]

what type of installation would you recommend to laminate steam from 30 bar to 0.2 bar (seal steam for a steam turbine)?
the supply pressure is fairly constant.
the system is used for start-up and shut-down of the steam turbine only.

one valve?
two valves?
orifice + valve?
valve + diffuser?
other?

type of valves?



saludos.
a.

 

[rmw]

How much steam flow does this turbine require at the 0.2 bar pressure?

rmw

 

[abeltio]

1.59kg/sec


saludos.
a.

 

[JimCasey]

I ran this through the Flowserve sizing program.
You need a 4" valve or you will have a sonic velocity problem downstream.
With the noise attenuation trim (Valtek's program selects a 6-tooth tigertooth trim) , schedule 80 pipe, and assuming 8db attenuation in the pipe insulation, the program predicts 86dB. You could use a steel Class 600 body and I would heartily suggest hardfaced seating surfaces and guide surfaces. Unless you have a lot of superheat you are not telling us about, the packing can be TFE V-Ring

I don't know your control logic but my first guess is that you would want this valve to fail open. air-to-close. You probably would want an opening travel stop so that the valve could not go too far open in case of loss of air. The selected valve in the referenced program would be at 86% of travel.

 

[quark]

There will be about 60⁰C superheating with the pressure reduction. You can reduce the steam consumption marginally by desuperheating(about 0.1 kg/sec). I would go with a two stage pressure reducing valve with desuperheating.

The specific volume of steam at 0.2 bar at superheated condition(I pressume it is gauge pressure) is 1.6669m³/kg and with 1.59kg/sec mass flowrate, the velocity comes out to be 337m/s(if I am not mistaken) with 4" pipe.