[Gasification] Gasifier Energy Balance

[Kermit Schlansker]

           I hope that someone will comment on my numbers

                 Gasifier Energy Balance

        Assume 100% input, heat energy.

Gasifier, 80% of energy goes to fuel gas, 20% goes to waste heat.

Gas cooler, Assume that 80% is chemical energy and 20% is heat energy, Thus chemical energy is .8*.8=64% and waste heat is .2*.8=16%.

Engine, 35% efficient .64*.35=.224  is work and .65*.64=.416 waste heat

Total of waste heat .2+.16+.416=.776 

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          If we assume that waste heat from the gas cooler and engine exhaust could produce steam at 400 deg F and this can be converted to work using a Rankine cycle at about 15% efficiency then mechanical energy from gas cooling and engine exhaust would be ( .16+.416)*.15=.0864 or  8.64% energy from Rankine cycle.  This indicates that Rankine work is about 40& of engine work. Use of the Rankine energy plus engine energy would then give .0864+.224=.310 or 31% work. 
          Since these numbers are only educated guesses there can be no exact result. They obviously need to be corrected by better guesses. However they clearly show that a gasifier is as much a furnace as it is a gasifier. We might as well round off the numbers and say that gasification without Rankine is about 20% efficient in producing work. With Rankine it could be about 30%. Of course the same line of thinking is applicable to all engines.
          It seems to me that the ideal place to put a gasifier now would be as a Combined Heat and Power system for a school. Of course you would have to consider fuel feeding, engines, and ash removal in order to make a commercial system.

                                    Kermit Schlansker