Where is the difficulty in controlling a wood gasifier? feed it good fuel, shake the grate and the rest looks after it self pretty much. I am able run successfully on woodchips with up to 30% water content. Main issues I have have been with augers and grate shakers but I am getting on top of that.
âWhere is the difficulty in controlling a wood gasifier? feed it good fuelâ
Exactly ⌠the difficulty is the fuel⌠the rest is pretty much easy 
have a gasifier ? find the good fuel for itâŚ
have fuel ? build a suitable gasifier for itâŚ
90% of the challenge is the operatorâŚ
10% of the operators are causing 90% of the troubles âŚ
not all builders are having the same high skill level as you have Gary⌠thats why nearly every gasifier will work if it gets in your handsâŚ
i have posted vids of the feed stock i use, without hopper or grate shaking other than the very slight tremour that is provided by the engine. a well designed gasser runs with very few glitches.
Yes, a very true statementâŚ
Bill S.: âTo operate a gasifier you need to do 1 of 3 things. One can purchase a a turnkey ready to run machine, 2: GEK has all the parts stamped out and then only assembly is required or thirdly get a welder and some scrap metal and follow a design.â A 4th option to operating a gasifier is find the nearest person with a working gasifier unit and ask really nicely if you can come visit them to see/hear/smell/feel how the unit works. The nearest person might very well be several hundred miles/KM away, depending on where you are located. Also, quite possibly that there isnât anyone in your country that has a working unit that theyâd be willing to show you.
The following is from my reading of the shared knowledge here. I have not operated any gasifiers beyond the camp-stoves made out of soup/paint cans.
One âcanâ crack the tar chains with heat, but it is WAY above the melting temperatures of steel, or non-specialty clays. Using a catalyst of large bed of hot carbon, EG the hearth of most gasifiers, one can crack those chains down into simpler molecules. Most gasifiers just call that part of the âreductionâ stage. One still needs to make a worthy gasifier and know how to operate it correctly to be able to crack these tars. That said, those tars only exist for a few inches of space within the hot core of the gasifier, not in the âfuel streamâ that has left the reactor.
One thing that I have heard repeatedly that deserves mentioning, and Iâm surprized hasnât been mentioned yet, is that gasifiers do NOT âsupplyâ woodgas and give it up easily. They must have their woodgas taken from them by force, litterally sucked out of them. Traditionally, this is done using the intake vacuum created by the engine one wants to use. The more the engine revs, the more it sucks on the intake, the more vacuum on the gasifier, the more woodgas is taken from the unit. This is a somewhat self-regulating process. The flow of gas can be hampered in by going out of the optimal range in either direction: 1. Not enough vacuum (âUnder-pullâ) and the unit cools down and doesnât produce enough woodgas. Too much cooling and you start to make tar. Engine rebuild time.; 2. Too much vacuum (âOver-Pullâ) and you pull the oxygenated combustion/pyrolisys zones too deep into the reactor. This turns your reactor into a wood stove, AKA âHeater Modeâ, where you are burning off all your woodgas inside the unit and only getting non-flameable smoke out the outlet. This also runs your reactor too hot which WILL melt your hearth/reactor vessel. Regardless of which opposite condition was occuring, a computer would only see the unit was not giving off enough gas and increase the throttle/fan speed to compensate; In Under-Pull, that is (probably) the correct option. In Over-Pull, that just increases the problem in a self-perpetuating run-away cycle until the unit is a puddle of slag.
Theoretically, blowing air (positive pressure) into the intake âshouldâ have the same effect as sucking on the outlet (negative pressure), but that doesnât stand up in the cases of a gasifier core. I think it is a thermo-chemistry thing, but Iâm not sure as Iâve only read what those who have used proven designs have said.
On a side note, a âMonoratorâ only allows a user to use somewhat moister wood, not change the dimensions of the wood fuel. It only lets the steam coming off the warm (100-200F, 37-93C) wood in the hopper condense someplace other than back on the wood, where it can be removed from the system into a sealed storage tank. A Monorator would theoretically allow a gasifier designed to use chunked wood to use 35% moisture wood chunks vs maximum 20% moisture wood chunks that the same unit without a Monorator would need; It would not allow that same unit to use 20% moisture wood chips though.
not sure your posting was meant to be here ?
a few dimes of comment dough:
A given gasifier can work ( produce good gas ) between 2 values minimum load and maximum load, depending the size of the engine to be used.
A correct sizing of the nozzles will reduce the risk in case off overpull, at max vacuum the gasifier will not be able to produce more ⌠the rest of air will come trough the mixer-air inlet.
Measuring with a computer and correct programming ( a computer is as smart as the programmer ) will reduce any risks significantly.
Positive air pressure is never the same as negative air presure, the chemical balance from the gas changes dramatically in favor of producing more Co2 , raising heat, decreasing the conversion rate of the bouduard reaction.
Positive pressure can work fine if the gasifier is constructed for positive pressure ( old style coal gasification for example )
My dime worth âŚ