Gas Compression: Engine Driver vs Electric Motor
Gas Compression: Engine Driver vs Electric Motor
(OP)
Has anyone had a recent experience with using an electric motor for a 5000hp gas compression application? We currently have units utilizing a JGZ compressor and are considering expanding with additional units that will be electric driven. I am not sure how cost effective this typically is, if any. I show my concerns for this electric consideration due to the circumstances. We are not regulated due to emissions, and the gas consumption cost for the original units are included in the rates, so we are not taking a hit on fuel. Adding an electric driven package will more than likely double our MCC size and I have a hard time understanding what legitimate reason would make sense to consider electric. With added softstarts, gear reducers (etc), I assume we are better off sticking with our original design and use the natural gas engine. Can you guys share your thought on this issue? Other than engine maintenance, what are we saving? Thanks for your replies.





RE: Gas Compression: Engine Driver vs Electric Motor
RE: Gas Compression: Engine Driver vs Electric Motor
RE: Gas Compression: Engine Driver vs Electric Motor
RE: Gas Compression: Engine Driver vs Electric Motor
Is this a constant speed application? Is it acceptable to run the compressor @ 720 or 900 rpm?
If yes, you may find the electric motor cost effective. As mentioned maintenance will be less, also no oil leaks!
If you desire a variable speed electric motor your initial purchasing and engineering costs will higher than a constant speed application. Either way you should not need a gearbox betwwen the motor and compressor.
RE: Gas Compression: Engine Driver vs Electric Motor
The Electric motor drive are cheaper to buy and install, about 30% cheaper. The operating costs of the electric are about 30% of the engine. But with VFD's and harmonic transformers, maybe a 10% savings
The units with VFD's didn't work well at all. The VFD's sign wave was pulsed and the little pulses cause the compressor to pulse and every discharge bottle failed. The units had to be run under 800 RPM. The units with no VFD, did just fine. Solution, get a VFD with 30 steps per cycle, not 12.
Downtime on the electrics was about the same as the engines, but its up to your electric provider. With big machines, you are a low priority in getting service back.
In the end, the costs are the same or favor the gas engine drives. Electricity is so expensive (in 1996 we had $.028/kW-hr).
RE: Gas Compression: Engine Driver vs Electric Motor
Other than that, the capital costs tend to be less with a motor, and the power costs can be significantly less (but that is subject to change as electric demand increases).
The answer for each facility needs to be developed for that facility. Often times one site will be able to come off an existing substation and other times your project will have to shell out $6-10 million for a substation.
David
RE: Gas Compression: Engine Driver vs Electric Motor
But, that said, you wouldn't have to worry about gas in the crankcase or water in the lube oil would you?
rmw
RE: Gas Compression: Engine Driver vs Electric Motor
There are some real maintenance savings, but never enough to scrap an existing IC engine and install a motor.
David
RE: Gas Compression: Engine Driver vs Electric Motor
RE: Gas Compression: Engine Driver vs Electric Motor
The taxes on CO2 for your electric compressor is double that on a gas engine.
RE: Gas Compression: Engine Driver vs Electric Motor
rmw
RE: Gas Compression: Engine Driver vs Electric Motor