3 replies to this topic

[LeoLeo]

Hello everybody,

Steam condition after steaming out or steam expansion is always a challenge. in out project we have a steam drum (DP 27,5 barg and DT 288C). To control the the pressure (@ 10,5 barg) inside the steam drum there is a control valve which vents the steam to the atmosphere. To control the noise level, there is a silencer at the discharge side of the control valve. The discharge side of the control valve is open to atmosphere and it is not pressurized.

Now the question is "what should be the design temperature of the silencer?"

I appreciate you opinion.

Cheers,

ARM

[kkala]

If steam in the dram had the design conditions, temperature at atmospheric pressure would drop to 247 oC (see attached "silencer.xls").
We do not know pressure upstream silencer at maximum flow, http://www.geothermal-energy.org/pdf/IGAstandard/WGC/2005/1345.pdf, which would define a temperature T higher than 247 oC but lower than 288 oC.
Design temperature for silencer can be conservatively considered as 288 oC. Difference from T is expected to have negligible cost consequence (if any).

Attached Files

•  silencer.xls   21.5KB   138 downloads

[TS1979]

Steam out of the silencer will be at the atmospheric pressure. Therefore, from the control valve to the silencer some where the steam will be at choke flow condition (most likely at the port of the control valve) - the silence at a maximum operating pressure of 5 barg (based on upstream pressure of 10.5 barg). With that maximum operating pressure and short piece of piping, I agree with Kostas that selecting the design temperature 288C may not have effect on the cost

[LeoLeo]

Thank you all for sharing information.

The pressure at the inlet of the silencer will be atmospheric. I was checking the Spirasx-Sarco website for some information.

This is the explanation, I found " In the case of a control valve, where the velocities in the connecting upstream and downstream pipes are near enough the same, the overall process occurs with constant enthalpy (isenthalpic). In the case of a nozzle, where the final velocity remains high, the overall process occurs with constant entropy. " The temperature difference will be a lot.

Based on the Spirax-Sarco explanation overall process will be constant entropy, not isenthalpic.

I agree that the cost effect is negligible, but I want to know what will be the final temperature in the silencer.