Fuel Maker FMQ-8-36 failure, fed from LNG stock

[gastronaut]

We have two Fuel Maker FMQ-8-36 units fed from LNG boil-off and we have experienced a high frequency of compressor failures (seized compressors) at less than 2500 hours run time, 1500 hours sooner than expected.

Does anyone have experience running a Fuel Maker off LNG feedstock?

The gas is warmed (ambient vaporizer) and odorized and regulated to 1.25 PSIG before it hits the FM units. We also have an inlet filter. I am certain it is not a temperature issue, the vaporizer is oversized and the gas temp is within 5 degrees of ambient after many hours of running. I'm thinking that the gas is so dry that we are getting premature wear on the cylinders.

I want to try oil injecting but this is challenging at low pressure and low flow. I may just replace the filter element with an oil saturated element from a different facility and hope the gas picks up some molecules on its way through the element. Adding a drip injector is another consideration.

Anyone have advice or experience they can share?

Thanks

[Amfuel]

Re: Fuel Maker FMQ-8-36 failure, fed from LNG stock

I read somewhere and it is my understanding that LNG has a different chemical make up. I'm not a chemist but this may give you a lead to investigate. It may be that you have to treat LNG as hot gas. (raw)

[larrycng]

Re: Fuel Maker FMQ-8-36 failure, fed from LNG stock

No experience with NG from LNG. NG, actually methane is an almost pure produce (methane) when it comes from LNG. Lack of oil is a problem, however, you really don't want oil in the fuel that enters the combustion chamber because can leading to carbon formation in the cylinder which would lead to possible detonation or pre ignition. This is reason for coalesing filter it the vehicle system; oil removal. In the compressor cylinder a little would be nice.

Capturing the boil off from LNG is a smart move both from an economic position as well as reducing greenhouses gases getting into the atmosphere.

Larrycng

[Gerben]

Re: Fuel Maker FMQ-8-36 failure, fed from LNG stock

I know Phill requires a tiny amount of water in the gas for lubrication, not sure about the FM series (tiny amount, so not soaking wet gas!). The easiest solution would be to mix pipeline gas and the boil off gas to get closer to or within normal NG specs. Ofcourse that can only work if the FMQ-8 is oversized and you have sufficient demand for CNG. I don't get the impression that is the case in your situation since you bought 2 FMQ-8's. I'd try the drip injector and use it to add a tiny amount of water.

[Amfuel]

Re: Fuel Maker FMQ-8-36 failure, fed from LNG stock

Anyone with thoughts on the temperature of the boil off entering the Q8?

[Gerben]

Re: Fuel Maker FMQ-8-36 failure, fed from LNG stock

The FuelMakers are designed to operate in Canadian climate. He's in California. A few degrees below Californian ambient temperature shouldn't be a problem.

[Amfuel]

Re: Fuel Maker FMQ-8-36 failure, fed from LNG stock

Since LNG boils off at -420d F that could be up to a several hundred degree difference. I hope it doesn't get that cold up there.

[larrycng]

Re: Fuel Maker FMQ-8-36 failure, fed from LNG stock

I believe the temp of LNG is -260 deg F. pipe the boil off through an heeat exchanger. If the material is compatable, and pressures low enough, (probably below 250 psi) try a air conditioning condenser to warm up the boil-off.

for wht it is worth
Larrycng

[Gerben]

Re: Fuel Maker FMQ-8-36 failure, fed from LNG stock

He already said he's using an ambient vaporizer. Those things can only bring the gas temperature to a bit below ambient temperature. His question was: is that enough. My answer: yes.