for a Cat stoichiometric 3516 @100% load, temperature can be between 462 C and 543 C depending on rating. At 75% load those figures are 449 C and 513 C. For a lean-burn version of the same engine, with higher ratings, the exhaust gas temps are 455 C to 465 C at 100% load and 449C to 461 C at 75% load. Lots of other specs on their website.
The engine in question is indeed turbocharged, it's a V16 Deutz running on land-fill gas. Can't remember the displacement - I'll find out, it's around the 24L mark, I think.
My son has recently started work for an electricity generator and remarked that the manifolds on this particular unit were glowing dull red and it certainly didn't sound right to me, but then I have no experience of methane as a fuel.
A quick check suggested that the temperature of the manifolds must be around 550-600ºC if he can see it and this seemed a little hot to me.
Hi Bill
We run naturally aspirated v12 Superiors on biogas. Assuming our temperature sensors are correct, exhaust temps generally run from 600-650. This varies a bit with changes in AF ratio and timing.
Cheers
Many thanks firefrog, your experience would suggest that the Deutz units have similar temperatures at the head face.
My lad can get hold of an IR gun thermometer so I've suggested to him that he takes a proper reading when he goes back on shift next week.
Hemi - many thanks. Your figures would certainly align with the visible condition of the manifolding.
I was wondering about AFR on these engines as I am advised that the flow of gas from the source (decaying rubbish) varies considerably with weather conditions. I had imagined that a variation in total mass flow rate would trigger a shut-down of one or more generators to prevent any extreme effects on AFR.
I suppose (but don't know) that the gas is buffered somewhere to help out this potential problem but I think I'll try to find out what AFRs are logged.
Watch what type of IR gun your son uses, they typically don't go high enough for exhaust manifolds and we've had a few operators wreck them trying to take EGTs.
Manifolds on these do glow a dull red but if the turbine housing is bright red, you've likely got clogged air filters. Canadian design temp for natural gas engine exhaust parts is 1000 degF (538 degC) and up to 1500 degF (815 degC) for brief periods.
Hi Bill
Our engines have a little different problem. The composition of the biogas is fairly consistent, but the pressures can vary significantly. If our pressure changes too much, the engines switch over to utility natural gas. It's a fairly smooth transition.
I can't imagine any system that would shut down or even trip the generator on a turbocharged, fully loaded engine. I would suspect some sort of 'btu calculator' is encorporated to adjust the generator load accordingly. I think that extreme changes in AFR would show some noticeable changes with the engine monitoring devices. That said, if the system is unmanned, there has to be some kind of alarms or protection mechanisms.
Cheers
I'm not familiar with that engine, but i'd bet it's a turbo charged lean burn engine?
It's quite common for the manifolds (and turbo's) to glow red when they are loaded hard.
Landfill gas is a nasty beast, the CO2 levels tend to make it burn a bit hotter as well, if I remember correctly.
I have only dealt with a few landfill gas power generation units nearby, and the main problem is getting consistent fuel. Hot days it runs rich, cooler days it borderline stalls. Just runs out of fuel. AFRC is a necessity (the only I mentioned above opted not to have one, and they are paying for it now...)
frog, I'm curious, can you tell us more about the system that switches to utility gas when the biogas starts to crap out? Like, who makes the system, what logic/condition triggers the switchover, and is switching back to biogas (when pressure is restored) done manually or automatically?
Hello
I'm not an instrumentation guy, so I can't give you many details or nuts-and-bolts explanations. I can physically see these devices and know basically what they do. Engine control is a ragtag combination of Alltronics, Woodward, and local talent. It's surprising it works as well as it does. The gas switchover is an in-house creation. There are two fuel lines running up to the intake manifold. Each has an on/off solenoid. The pressure sensor is located on the biogas line. In high or low pressure situations, the utility gas solenoid is activated. Then the biogas solenoid closes. Biogas has to be reactivated manually.
Cheers
frog, thanks for the explanation. There seems to be a market developing for turn-key fuel switching and even fuel blending systems, hence my curiousity in your application.
