Recomendations for larger steam pressure reducing valve

[KevinNZ]

We have application where we need to reduce steam pressure from 18 to 9 bar.a and the flow is 130kg/s. The valve also needs to be sized for 12 bar.a upstream pressure. There a lot of energy here and vibration and noise needs to be controlled.

 

[mk3223]

May contact different Sales for quote the valve based on the design conditions as specified. The proposal may provide the detail of the valve with the operation concerns regarding the noise, vibration, etc., and any mitigation as needed.
Per your process conditions, just wondered that is the valve to be operated in the different upstream pressures, i.e. the process to be changed from 12 to 18 bar.a, with the constant downstream pressure of 9 bar.a?

 

[KevinNZ]

Thanks MK233

The valve controls the upstream pressure with a set point between 18 and 12 bar. Downstream pressure is constant.

I have seen Flowserve valves used for this application. Hoping someone would know other valve companies with experience this application.

 

[mk3223]

May Google the Fisher-Emerson or Masoneilan valves for additional information for your application. Good luck.

 

[ValveWagen]

I believe a sliding stem control valve with noise-attenuation trim will be able to solve your problem. The trim will bring down the noise to low level but it has one downside which there should have no particles which could clog the cage. Better to install a filter upstream for it.

Look for Emerson-Fisher sliding stem control valve with whisper trim. I have seen that worked for many such cases.

 

[pennpiper]

KevinNZ,
What is the line size for your situation?

Sometimes its possible to do all the right things and still get bad results

 

[HitokiriAoshi]

best suggestion is to use multiple valves if space allows, will drive total cost down over time.

for example, spend more on a high priced body guided precision machined y pattern globe valve for 1st stage drop, then spend less on the second control valve if you need a control valve.

 

[georgeverghese]

That is a lot of energy wasted if you just let it down with a PCV - is there not economic justification for a power recovery expander here? Some makes of radial flow expanders can tolerate up to 50%wt of the expander exit stream as dispersed liquid phase. The more superheat in the feed stream, the more energy you could recover. Maybe even a 2 stage expander with intermediate phase separator ? On the brake side of the expander, you could have a pump, or electric power generator, or a gas compressor. For times when you have an expander breakdown, install a backup low noise trim PCV on a parallel piping run.

 

[KevinNZ]

Pennpiper
The flow is 130 kg/s. Line size upstream DN1100, down stream DN1200, but this would be reduced next to the valves.

georgeverghese
A back pressure turbine is being considered but in anycase a the pressure let down valves will be needed for by-passing the turbine.

 

[georgeverghese]

Okay, so this is the backup PCV to the power recovery backpressure turbine. Run the calcs on this JT letdown to see if it is 2phase on the exit - if it is, then you'll need hard faced trim to handle the very erosive conditions (commonly called "wire drawing", if I remember the term correctly). To enable quick response to a turbine trip and prevent from blowing the PSV on the upstream side, quick open style trim will be required. Adding a pneumatic volume booster at the PCV actuator will also help - use an oversized instrument air supply line to the pneumatic booster.