[Gasification] Solid Fuel Gas Turbine, was Re: Where is Everyone?

[Bob Stuart]

Another option has occurred to me for single house size units.  Turbines 
always lose efficiency as they get smaller, with a higher surface/volume 
ratio.  Since I'm only looking for pressures in fractions of 
atmospheres, vane pumps and/or rootes blowers might be more suitable.  
Could regular injections of a solvent or cleaning solution prevent 
excess tar build-up?

Bob


On 17-01-03 01:39 PM, Bob Stuart wrote:
>
> Thanks again.  This has saved me a lot of trial and error.
>
> It sounds like I should try using plenty of air to minimize CO 
> content, preheated for secondary combustion, and a cyclonic separator 
> for the ash, probably with another filter as well, perhaps 
> electrostatic?  Air lubricated bearings seem wise as well.  The 
> impeller case should open with the feed door, swinging a rotary wire 
> brush into contact with the turbo, angled to both clean and turn it 
> slowly.  The magnet needs a strong enclosure to handle the centrifugal 
> force, and careful balancing.
>
> As usual with gasifiers, price does not go down well for a 
> small-capacity rig, so solar may have this beat for home use now.  
> Maybe I've just dreamed up a good way to get forced draft on a 
> condensing stove using low-tech impellers.  I hope someone will find 
> this inspiring for a larger scale unit.
>
> Bob
>
> On 17-01-03 12:06 PM, Doug wrote:
>> Hi Bob,
>>
>> Coking is caused by the reversion of CO gas back to CO2 and carbon 
>> soot, where-by the hot gas entering the turbo is over a temperature 
>> of say 500C. If you were to first combust this gas with air so that 
>> only CO2 hot gas drove the turbo, the problem then becomes one of ash 
>> particle impaction onto the impeller blades. Naturally you get heaps 
>> of waste heat, but the practicalities of cleaning the impeller daily 
>> or after each refueling is a real party pooper! The only safe way is 
>> to use ceramic filter candles, expensive and needing compressed air 
>> to pulse clean.
>>
>> Not sure maths is all that's required to make your idea work in the 
>> way you perceive without adding energy. Steam and coke need the high 
>> temperatures and pressures associated with turbo operation, but in 
>> differing design application. I'm sure others will offer you comment 
>> to develop this interesting concept.
>>
>> Doug Williams.
>>
>>
>>
>> On 03/01/17 12:56, Bob Stuart wrote:
>>
>>> Thanks, Doug.
>>>
>>> I'd been worried about coking, so you have saved me a test setback.  
>>> Will a cyclonic separator upstream help?  I've never dealt with 
>>> coking, so I don't even understand its vulnerabilities.  Would a 
>>> good wire brushing with each new load of fuel do the trick?  That 
>>> could be automated pretty easily.
>>>
>>> All the ICEs have to deal with the power for a compression stroke.  
>>> I'll do the math on intake vs exhaust volume before building, of 
>>> course, to make sure the turbo efficiency is a minor fraction of the 
>>> equations.  With a built-in air pump, a condensing flue is easy to 
>>> arrange, and it recaptures any heat used to burn wet wood.  Would 
>>> the steam help clean coke?  It eats carbon in an ICE.
>>>
>>> From what I know about generators, a rapidly spinning magnet is 
>>> quite effective.  Those little DC-DC voltage converters are 
>>> surprisingly small and efficient, running at very high frequencies.
>>>
>>> Bob
>>
>>
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>
>
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