12-28-2013 09:33 PM
We have 6 G3520C 50 hz 1966kW in a landfill in Argentina.
Our siloxane level between service and oil change (every 1000 hs), is about 80 or 90 ppm, and we are making TopEnd service about 8k or 9k hours because the detonation level don't leave use the engines at 100% of load.
We use a siloxane removal system supplied by PPTek UK.
Did you has some kind of valve failures? or problems with another thing
11-29-2013 04:42 PM
Fuel Correction Factor is telling you how accurate your CH4 or BTU value is. At my plant we have a gas analyzer that takes a sample every 15mins and updates the CH4 value in the generator's PLC, from that they calculate the BTU value and send that to the engine ECM. To calculate CH4 to BTU just multiply by 9, 55%CH4 = 495BTU.
I use the Fuel Correction Factor to tellme when I need to calibrate the gas analyzer. If it stays low for a day or so it is time to calibrate and most of the time the gas analyzer is out of calibration.
If the fuel Correction Factor is below 100% then you CH4/BTU content is greater then the reading it is reciving, if it is higher than 100% then it is less than the reading.
Let me know if you have any other questions
09-25-2013 06:03 PM
Sorry, that ends up being an answer that start with "that depends". The correlation between the amount of siloxanes in the fuel gas stream and the actual deposit formation on cylinder and other hot surfaces is not always clear cut. I have dealt with a number of sites where the siloxane levels were well above the CAT (and some other manufacturers) guidelines and found the actual deposit levels manageable. Have been on other sites with "acceptable" siloxane levels and severe deposit problems.
Some of the things I have found are,
Other fuel gas contaminents, such as organic compunds, sludge, tar, acids, CFC's and salts.
Moisture level of the gas, sometimes a "wet" fuel stream with a good water reduction system also seems to wash a bunch of problems out of the fuel stream.
Engine operating temperatures, sometimes varying the coolant, or lube oil temp or both a few degress appears to have an impact on deposit formation.
Lube oil additive packages, levels of sulphated ash can contribute to the deposits.
Engine load factor, affects both lube oil control and cylinder temperature, under and over loading can affect deposit rates.
The published guidelines are just that, a guideline based on a value and a given set of assumptions. Running engines on biogas requires active involvement by the operator and the ability to be flexible to change as needed based on how the engine reacts to the fuel gas stream.
Your best infor,ation will likely come from operators of mulitple sites. Along with what the siloxane levels are you need to get a better idea of some of the other contributors mentioned, at least in my experience.
Regards, Mike L.
09-24-2013 07:07 PM
We have supplied customers, in Australia, with large numbers of G3516 Landfill Gas generating sets, and they have accumulated huge numbers of running hours. The gas treatment processes are fairly basic and economical. And, we know that the G3516 is a good deal more tolerant of the presence of siloxanes than the G3520C. The siloxane content, in our G3516 customers fuel, is almost always higher than the recommended limits in the CAT Gas Fuel A&I Guide. So, the feeling is that the A&I Guide may be a bit too conservative, at least for the G3516.
Our customers are now looking at using the G3516C and the G3520C Low BTU engines. Since we know that these are less tolerant of siloxanes than the G3516, we expect that improved gas treatment will be necessary, however we need to get some idea of how much improvement may be necessary (still thinking that the CAT A&I Guide may be too conservative).
What practical levels of siloxane contaminants can the G3520C and G3516C really tolerate without developing piston deposits or detonation problems?
06-21-2013 09:41 AM
We have @12000 hrs on a G3520 LFG unit with approx 90-92% operation. Currently doing first top end overhaul......Other then routine maint. the only limiting factor we experianced was fuel availibility.........
05-19-2013 12:10 AM
We have 6 engines in a landfill in argentina, we have 4000 hours of generation and the problems detected was.
failure in 1 throttle.
failure in 1 asm.
failura in 1 ecm.
we change the lube oil and filters every 1000 hs.
our level methane varies between 50 to 60 %.
11-17-2010 06:24 PM
Experience based on my area, about 30 years total NG engine experience,
Natural gas fueled prime power and cogeneration units, averaged 8400 hours/year
Biofueled engines, same service (landfill and digester gas) averaged 8100 hours/year