Efficiency of Gas Engines

Chris Olson wrote:

r john wrote:
Looking for a new engine capable of driving a minimum 500kw generator. I appreciate the micron size but we have that covered as our charcoal slurry is technically an emulsion.

Cummins has nothing that small, and nothing at present the meets Tier IV/EU Stage IIIB. In the KT's that we modified for mining use in the late 90's we used conical pattern injectors with 20 micron slurry. None of those engines are in service anymore. There were several problems. Standard injectors do not work at all because the coal particles are very abrasive to injector tips. There was also excessive wear to the liners, top piston ring and ring land due to abrasives in the fuel. I don't know how you managed to turn coal dust into a liquid to get an emulsion though. An emulsion would usually suggest two liquids. If it has solids in it, then there has to be a micron size for the solids, and when you have solids in the fuel you have filtration issues and abrasives that must be dealt with.

Frankly, the huge hurdle right now for all engine manufacturers is meeting US EPA and EU Stage emission specs. Here in the US the directive for 15 ppm sulfur fuel (ULSD) was necessary to be able to use DPF and NOx absorbers. This gets increasingly hard with coal dust. So most of the current push in research is in coal-to-liquid diesel fuel production where the sulfur can be removed in the gasification treatment when making diesel fuel with the Fischer-Tropsch process.

The Cummins QSK-series is presently available in dual fuel configuration for diesel fuel only or diesel/natural gas. And, according to my associates that work at Cummins, alternative fuel technology is constantly being worked on, including coal slurry. But there is nothing commercially available at present. And more than likely, when it does become available it will be for the QSK78 and QSK95 at power ratings of 3,500hp and up. The investment in engineering time to develop special fuel engines that meet EPA is not justified in sub-2,000 hp classes because it is not profitable.
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Chris

Chris

The 500kw generator was the minimum size anything bigger is a bonus. Where not actually using coal but torrefied wood (charcoal) so we dont have the sulfur and NOx problems. As for the emulsion its a coloidial process similar to making peanut butter but adapted for charcoal and water. I was led to believe Cummins had solved the wear on injectors by a new design of injector with hardened pistons and liners.

r john wrote:
I was led to believe Cummins had solved the wear on injectors by a new design of injector with hardened pistons and liners.

No. None of the trial engines ever had anything but stock pistons and liners. The fuel systems were the only thing modified. Where a KTA50 should run 1.5 million gallons between overhauls on diesel fuel, on coal slurry they would run 300,000 - 400,000. When you inject a fuel containing abrasives it is no different than running an engine with a hole in the air filter. Water simply flowing over rock will erode rock and create canyons. Mix fine particles of dust in it and inject it into an engine and there are considerable challenges. Where diesel fuel acts as a lubricant, coal slurry acts as a cutting fluid.
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Chris