reciprocating gas compressor unloading
reciprocating gas compressor unloading
(OP)
Good Day
I'm working in an engineering company and one of our projects is a gas compressor station which includes 4 trains of reciprocating gas compressor. Currently we are in detailed engineering phase of that plant. The issue that we have in most of our projects (which are mainly gas gathering and compression plants) is that the process of the plan requires compressors to work under 25% or 50% of their capacity for long period of time( in some points during life cycle of compressors) which is very harmful for compressors and valves and causes excess heat in compressor body, valve and... . the main method that we use for unloading is suction valve unloader + spill-back( cooled bypass from discharge after-coolers to compressor's suction scrubber), but we prefer valve unloaders.
someone said to me that a hoerbiger HydroCOM system has overcome the the issue and we wont have overheating of our compressor if we install that system and it's the only solution if we want to operate compressors under 25% or 50% unloading continual.
but I don't understand how a valve unloading system(even HydroCOM) can solve that problem. any one have similar experience? or is there any way to perform continual unloading without any problem?
Thanks in advance.
I'm working in an engineering company and one of our projects is a gas compressor station which includes 4 trains of reciprocating gas compressor. Currently we are in detailed engineering phase of that plant. The issue that we have in most of our projects (which are mainly gas gathering and compression plants) is that the process of the plan requires compressors to work under 25% or 50% of their capacity for long period of time( in some points during life cycle of compressors) which is very harmful for compressors and valves and causes excess heat in compressor body, valve and... . the main method that we use for unloading is suction valve unloader + spill-back( cooled bypass from discharge after-coolers to compressor's suction scrubber), but we prefer valve unloaders.
someone said to me that a hoerbiger HydroCOM system has overcome the the issue and we wont have overheating of our compressor if we install that system and it's the only solution if we want to operate compressors under 25% or 50% unloading continual.
but I don't understand how a valve unloading system(even HydroCOM) can solve that problem. any one have similar experience? or is there any way to perform continual unloading without any problem?
Thanks in advance.





RE: reciprocating gas compressor unloading
Seems like a better way than forcing dependence on one vendor's system.
What would you be doing, if you knew that you could not fail? Ans. Bonds and derivative brokering.
RE: reciprocating gas compressor unloading
Each Train consists of 3 reciprocating compressors (2 working+1 standby) and final train compress the gas to about 2000psi. So considering the capacity of compressors (each about 15000 kg/hr depending to the stages), increasing the number of compressors doesn't seem economic, but it is practical I guess.
RE: reciprocating gas compressor unloading
Firstly, you need to determine what the minimum load the driver needs to maintain...for example, a Caterillar gas-fueled engine you probably want to keep it loaded to at around 60 to 70% load minimum....they advertise 50% load, but I'd be conservative. So, that's one contrainst, you'll have to consider, along with minimum speed, discharge temperature and gas cooling capacity.
You mentioned pockets, valve unloaders and recycling (spill-back), all of which are good capacity and load control options, as well as speed control. Another option, is suction pressure control. You cand affect both compressor/engine load and throughput by lowering your suction pressure, or even discharge pressure.
RE: reciprocating gas compressor unloading
RE: reciprocating gas compressor unloading
RE: reciprocating gas compressor unloading
Johnny Pellin
RE: reciprocating gas compressor unloading
Yes, they are in series and each compression stage(train) feeds the other one till it compress the gas to 2000psi. I think a 4 throw frame would be enough for our purpose, because it's hard to achieve 25-50-75% unloading on a 6 throw frame if we going to use the valve unloaders only.
RE: reciprocating gas compressor unloading
RE: reciprocating gas compressor unloading
That doesn't even make sense to me. The logic and controls will cost more than the units.
put in 12 4 stage units, then use unloaders spillbacks whatever and you'll get a low end of 3% of design flow if you need to be that low.
RE: reciprocating gas compressor unloading