Jim, are you proposing to build these? Bruce

Hi Bruce,

Jim said at:

http://www.gekgasifier.com/forums/showthread.php?t=65

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as for scaling up the gek, i've already done the basic scale up studies. the summary is below. the gek design is based on a series of formal ratios and stock dimensions, and by propagating those out across common north american tank sizes, the sizes of step up follow. at some point i'll write out these formalisms in detail. but for now you can see the resulting four sizing steps for the future below, somewhat indulgently named: small block, big block, mountain and merlin.

we are not making any of these other sizes for regular production, as just keeping everything straight on one size is more than enough at the moment. if/when people really need these larger ones, i can rather quickly elaborate the cad files to make them. it is pretty much a scripted design system at this point. elaborating new sizes within the basic system is not difficult. and really, most everyone wants small scale gasifiers, until they are doing vehicles or industrial applications. thus why we started at the current default GEK scale.

Terry

Hi Jim,
what would be feed rate (kg/hr) of raw chips for a Merlin GEK size? Igor

Fuel flow will scale in proportion to the cross-sectional area, which in turn scales as diameter squared. One can rightly quibble whether to use the hearth dimension or the vessel size dimension. Using the hearth dimension, going from a 3" diameter hearth to a 10" diameter hearth, the Merlin will flow (10/3)^2 = 100/9 = about 11 times as much fuel as the "small-block".

I don't know if anyone has confidently asserted what the standard GEK's flowrate is. Until someone does, I'll provide an estimate that a 3"-throat standard GEK should be expected to flow (this is based on a 2.5 m/s hearth "cold gas" superficial velocity) 11.35 litres per second of cold gas. Assuming 75% cold gas efficiency and 5500 kJ/m3, that's a gas output of 62kW heating value, and a fuel input of 83.3kW (19.6 kg/hr of 15% m.c. wood). Using the conservative figure of 1kg/hr wood being able to produce 1hp of engine power, that indicates that a standard GEK can power a 20hp engine.

So my calculated baseline GEK numbers are: 83 kW thermal input, fuel flow 19.6 kg/hr 15% m.c. wood, air flow 26.6 kg/hr (12.8 scfm), and can nominally fuel a 20hp engine

Scaling this 11X, we'd expect to see the Merlin take in 915kW of fuel (I'd be tempted to call it 1 MWth in round numbers), which is 215 kg/hr of 15%m.c.. Air flow would be 292 kg/hr (141 scfm), and it would be able to nominally fuel a 220hp engine.