GEK v4.0 gas cowling with side access port
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Posted 05 April 2010 - 10:34 PM
the first v4.0 gas cowlings are going out this week. here's three in the paint booth a few days ago. these get insulation on the inside of them, then a ss insulation sleeve to hold it in place and face the gas.
for the v4 we're changing from the previous rotary grate to a side shake grate, along with adding an access port in the side of the cowling. the change to the side shake grate is motivated by easier automation, more consistent char passage and the ability to easily change out grates with different hole sizes for different fuels.
i originally though a center post would be easier to mechanize/automate. problem is you need back and forth sharp movements to really knock the ash out. with a motor and pulley, this requires a reversible motor and polarity switching mechanism. it is not an easy on off switch.
the center post also ended up fabricated into the grate. we've now well separated the grate from its supporting structure, thus you can change out grate perf sizes for different fuels and char purging rates, without having to rebuild the full grate. you now only need to change the perf disk. we default to 3/16" holes in the grate, but at times have used down to 1/8" and up to 1/4".
the rotary grate was also motivated by the desire to have an air up from the bottom via the center tube. no one is using / doing this, so maintaining this potential seems less a priority two years later.
the rotary grate creates more movement on the sides vs the center, and has more hardware blocking the center of the grate. thus its purging distribution is opposite of what is ideal. you'd rather prioritize center purging as this is where the gas flow is less, and where things are likely to start staking up. both methods will work, but the side to side shake method seems a bit superior.
the side access door replaces the bottom ash removal port. the bottom ash removal used an ash rake on the rotary grate to rake the ash over and out the hole. now you use a rake in the side, or add a 2" auger to the npt plumbing hole provided.
the ash bin is also two inches deeper to support longer runs. past here the ash auger will take the ash out the side and into an external ash bin.
all of these changes are relatively minor. they are just little details that increase the usability of the gek in response to what we've learned over many hours and sites of use.
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