Multi steps gas pressure regulation, compensate temperature drop
Multi steps gas pressure regulation, compensate temperature drop
(OP)
Hi,
In gas compression (with reciprocant compressors & combustion engines) sometimes we have no option but taking fuel gas from the discharge line. Given the most common escenario we usually encounter there is a gas feed at 70 kg/cm2, whereas our fuel stream pressure needs to be around 7 kg/cm2. Considering a discharge gas temperature of 40 deg C, this will imply, in a single step pressure reduction, that our fuel gas supply would be around 8.5 deg (using a rule of thumb of 0.5 deg C reduction for every kg/cm2 reduced).
Leeting alone possible choked flow escenarios, and the above implying we need a multi step pressure reduction (two steps) Is there any general recommendation for distance between valves in order for the gas to recover temperature before entering the following regulator valve? (we generally work with 35 deg C ambient).
Thank you in advance.
In gas compression (with reciprocant compressors & combustion engines) sometimes we have no option but taking fuel gas from the discharge line. Given the most common escenario we usually encounter there is a gas feed at 70 kg/cm2, whereas our fuel stream pressure needs to be around 7 kg/cm2. Considering a discharge gas temperature of 40 deg C, this will imply, in a single step pressure reduction, that our fuel gas supply would be around 8.5 deg (using a rule of thumb of 0.5 deg C reduction for every kg/cm2 reduced).
Leeting alone possible choked flow escenarios, and the above implying we need a multi step pressure reduction (two steps) Is there any general recommendation for distance between valves in order for the gas to recover temperature before entering the following regulator valve? (we generally work with 35 deg C ambient).
Thank you in advance.
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RE: Multi steps gas pressure regulation, compensate temperature drop
Best regards, Morten
RE: Multi steps gas pressure regulation, compensate temperature drop
There is a proper way to do this - install an electric heater UPstream your first regulator to heat the gas to about 60 to 70 C, then let down.
Or you could run a few loops of pipe ( say 5m in total) downstream the hot air blast from your radiator on your engine or even take a side stream off the radiator water into a HX and run the gas through that.
Initial gas to run the engine might get a bit cold, but once the engine has warmed up away you go.
Just straight pipe in still air you would need about 100m.
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RE: Multi steps gas pressure regulation, compensate temperature drop
RE: Multi steps gas pressure regulation, compensate temperature drop
Best regards, Morten
RE: Multi steps gas pressure regulation, compensate temperature drop
RE: Multi steps gas pressure regulation, compensate temperature drop
Going from 70 down to 7 can be quite noisy and expensive.
There may be a small relaxation in temperature between the two, but not enough to make any appreciable difference unless you wrap the interconnecting pipe in electric trace heating. Even then the amount of heat you can get in is quite low - It just might stop the pipe freezing.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Multi steps gas pressure regulation, compensate temperature drop
RE: Multi steps gas pressure regulation, compensate temperature drop