attempting to use grain for gasification
Posted 07 November 2011 - 02:46 AM
I think you are right and below is the latest run we have done
You can see how the gas outlet temp jumps after 11 minutes...fan was turned off while the gas ring was being removed...temp then falls when fan restarted, jumps up presumably due to actual fire in the furnace, falls as more fuel is augered in, jumps when that stops, then falls again as more fuel is augered in. The exit gas lit at about 15 min. At about 18 min we augered fuel until the agitator current increased to about 2 amp, when fuel feed then became a series of short bursts regulated by the current pull of the agitator. The whole unit reached equilibrium after about 28 min when the outer skin of the thing was at about 240 deg C. We then left it running, although the trigger agitator current was reduced at 28 min and and air flow was reduced at about 25 min, and increased at about 65 minutes. Anyway, as you suggest the temps are not hot enough...the gas will run an engine but only just.
Our next move will be to insulate the whole thing by wrapping it in 50 mm rockwool, and see if that pushes the temp up a bit. I also want to check if increasing the agitator current may also make it run hotter...that initial temp rise may indicate something.
On the plus side, I am pretty happy that we can get this thing to operate in a stable way...just a matter now of optomising the amount of stuff in the furnace, airflow, and insulation I hope.
If the above fail, I will try putting in some carbon as you suggest
Posted 20 November 2011 - 09:44 AM
The run data are shown below, but the main feature is that we achieved much higher exit gas temperatures, and could maintain this at >500 deg C. Interestingly, the higher temperatures were achieved by reducing the amount of material in the furnace (ie reducing the current draw of the agitator). My impression was that we were manipulating the fire-front...too much fuel and it smoulders, while at the other extreme the fire goes back down into the furnace...a matter of getting it just right at any given gas flow. The spread in temp readings after 180 minutes was due to carbon buildup on the thermocouple causing current leakage to earth...it was cleaned at 250 minutes and that fixed the problem. Variations in the outer skin temp are related to changes in air flow...less flow, gets hotter.
We ran the Honda engine, and it ran much better indicating the gas was a better quality, however our filtration needs work
Posted 09 January 2012 - 06:04 AM
IMG_0002-1.jpg 33.91KB 0 downloads..just one of our highly trained engineers working on the beast
Thought we should post something to show we have not given up
Posted 10 January 2012 - 02:59 AM
Is the coke tray going to be the coal bed and you dump the grain on top of it? Were you only using grain before and no charcoal base?
How long of runs have you had the engine going so far? Have you been capturing the outgoing gas temp and feeding it back into the incoming air or using the heat from the engine exhaust to preheat the incoming air? Any inside pictures would be greatly appreciated. Thanks,
Posted 16 January 2012 - 12:54 AM
The incoming gas flows down the outer wall of the furnace, so heated, enters from the bottom. The biggest surprise is no ash to deal with...the grain sort of turns into a rice bubble and when it gets small, floats up and out the outlet (wheat is only 4% ash which helps)...hence our desire to install a sort of internal cyclone, as the small carbon particles stick to the first cool surface they come to and quickly form a deposit. We are also toying with the concept of periodic "burn outs' to deal with this...sort of like the particulate filters fitted onto diesel truck exhausts.
The fuel amount in the furnace is very small, only a couple of inches at most and is added to almost continuously at just the right rate. I suspect it is a type of semi fluidised bed type system we have ended up with accidentally.
Posted 28 February 2012 - 04:38 AM
Pic below is of the engine and pump, with gas connected in where the aircleaner used to be
showing wet scrubber (aquarium tank pump in RH bucket moving water into the LH bucket full of chips...design from this web site), then going to a oil bath aircleaner, then to a paper cartridge filter, then off to the engine)
The outlet now is a simple sort of horizontal cyclone, going up to the burner on top...here it has been shut down with a cap and the engine is drawing as through the gasifier. The outlet pipe to the engine is on the LHS and the thermocouple is on the RHS to sense the outgoing gas temp. It looks as if 600 deg C is a good temp to use and you can see how all the paint has been burnt off the horizontal cyclone
Posted 28 April 2012 - 12:08 AM
At the start of WW2, wheat was in short supply due to drought and the need to feed Europe (specifically the UK). With the entry of Japan into the war in 1942 (well, late 1941), shipments of wheat to Europe became more difficult due to enemy action. About this time, several years of low wheat production reversed with the breaking of the drought in many areas. Australia had more wheat than it knew what to do with. However, supplies of charcoal were still in comparatively short supply (and expensive) - particularly in some rural areas where land clearing had removed the timber suitable for charcoal production. A few people, Martin in particular, started experimenting with the use of surplus wheat as a fuel in the producer gas process. Immediately, they ran into problems because wheat in the conditions prevailing in the combustion zone of a gas producer unit formed a clinker (silicone?) which rapidly blocked the system. From memory, Martin was one (possibly the only one) who devised a form of shaker to break the clinker and allow unburned wheat to enter the combustion zone (strictly speaking, to allow unburned wheat to fall down from the hopper zone into the combustion zone at the base of the unit). I think the wheat burning units may have had a limited following in city areas.
It is unlikely that too many other countries ever experimented with wheat - at least during WW2. All of Europe and Russia needed it for food etc. The US was never much into gas producers at that time and I don't think Canada had much need for them either. IN terms of wheat for the motorist, Australia probably did it alone. In my recollection, wheat did not attract a large following although I cant speak for WA where farmers were utilising producer gas in tractors well before the war.
Posted 17 October 2012 - 11:16 PM
Please continue to keep us informed about your progress.
Posted 12 November 2012 - 10:59 AM
Still active, but somehow haven't got round to posting for a while. Still on a steep learning curve, but it seems to come down to this...grain ash melts at about 700 deg C, so we cannot use a throat and high temps in the furnace to reduce tars...hence very poor quality gas. Two solutions...bleed off and condense stuff at the pyrolysis stage, or pass the exit gas over a very high temp section made by burning some of the gas to heat a section of exit pipe. Both solutions have been done before, and we just need to find time to build the darn thing and get it going...I have two very useful sources of info ....one is the experiences of a chap called Kurt Johannsen who ran a truck on wood scraps in the centre of Australia for many years...his equipment is now in the truckers hall of fame I believe...the other is a patent taken out by Martin detailing the above modificatios for gasifiers running on grain...if I can work out how to put these documents on the forum I will, but I struggle sometimes
Thanks for the interest
Posted 21 January 2013 - 10:21 PM
- Fuel treatment / preparation / production
- Gasify this "revised fuel"
The reason I wonder this, is because 700C melt temperatures are really low and are going to always give you a headache. Worse, if you are a famer, you absolutely need your tractor to run perfectly when it is time to run it. Problems with a gasifer stopping plowing or harvesting would be a disaster at these critical times.
At least part of this fuel problem could be reduced by extracting the useful part of the chaff / rice / grain into the desired fuel - off line, and then using this "better fuel" to run your gasifier.
Just an example of what I am thinking:
Fuel Preparation Stage:
- Dry the grain - really bone dry (of course being very careful about ignition)
- Pyrolize this dry grain at around 500 C or so to extract the volatiles, but keep it below melt temperatures. Try to avoid getting grain biproduct into the volatiles.
- Rapidly cool these volatiles to pull out the solids / flowing liquids / gas.
- Burn the gas portion to dry and pyrolize the grain
- Use the solids organics, perhaps mixed with coal / charcoal / wood in the gasifier as needed.
- Some people have attempted to use the liquid portion as a diesel fuel substitute, although this is not that easy
The goal hereis to sort of concentrate down the fuel value into a form that is easier to use without all of the rice silica blowing all over.
I have not tried this, it is just an idea.
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