Yevgen Kolyvan “Joni” has found through experimentation that around 20 degrees upwards is the ideal angle. It makes his gasifiers insensitive to fuel size, he’s even used fist sized chunks at times, but he typically uses rebak chunked wood or chips found on the side of the road. The upwards angle helps to prevent bridging.
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Maybe I’m thinking wrong, but wouldn’t angled up nozzle be vulnerable to filling with debris?
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20 degrees isn’t that much, and from Joni’s pictures they don’t appear to have any junk in them.
The air clears it I would think. Kristijan used an upwards angle with his Double Flute build.
Edit: Forgot to mention, even the MEN gasifier had direct parallel to the walls vertical pointing nozzles. Ron Lemler may be able to confirm how well they work.
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I like your well thought out and written statement AnteroS.
Perceptive. On how flows must occur.
I have always been uncomfortable with the cold velocity method. In the Oxidization heat making zone all gases passing will be heated and will increase in volume. To keep flowing down, either the velocity must be increased; or the flow areas increased; and/or flow resistance would seem must be decreased.
Now a bit farther down in the flow through Reduction areas the compact combined H’s C’s and any remaining O’s , or ripped free O’s molecules are reduced (even O2 into free available - lost and lonely, O and O) and re-combined into separate simplified gas molecules. The compact solid carbon char chunks converted into more space taking up gaseous.
Forced flow; and rapid cooling keeps things working in balance.
Static blower flow loads are what are deceptive in developing. "In a perfect world . . "
Use engines for true real world results.
A solids to gaseous gasifier you are always juggling at least three active factors. Often five. Sometimes more.
Do not drop the many plates spinning or balls up in trajectories!
Steve Unruh
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I’m late to the party as usual, but the chemistry question about where the oxygen goes caught my eye. The carbon in the wood or charcoal combines with one oxygen to make CO, which is a flammable fuel gas, which combusts in the engine to make CO2. This has probably been covered here already, sorry to be redundant.
But here’s what I think is the fun part:
You wouldn’t think of an air-combusting fuel to already contain oxygen, but it can. That is a distinct feature of alcohol fuels (ethanol, methanol, etc), that they have an oxygen atom in them. And they will react in a combustion when you add some more oxygen.
Then there are fuels that already include all of the oxygen they need, without an air mix, such as thermite, sugar rocket fuel, gunpowder, and so forth. In terms of the fire triangle, the only thing needed for combustion is some heat to kick things off. Fuel and oxygen are already there. The oxygen jumps off of its “storage” atom, and onto the fuel atom, releasing the combustion energies.
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Antero, I did take the time to read it all and you have my utmost respect for taking of your time to give such a thorough explanation from your perspective. I really appreciate it and of course everyone who has contributed to this thread. It has greatly broadened my understanding of the process.
You had mentioned turbulent flow like when an aerofoil stalls - I know exactly what you are talking about since I used to be a pilot and also build aircraft.
Your explanation and the contributions of everyone on this thread are exactly what I had hoped when I started this thread, to understand the process better, because to understand the process is to understand the theory of the design. Back to the aircraft analogy, this is the reason we have different types of airfoils (wings to the laymen) with different design properties allowing different functions - neither is wrong, just different, some fat squared off wings like on a small plane allow for slow flight, while some narrow swept back wings are not suited for slow flight but are made for jet aircraft. As it applies to gasifiers it therefore helps me to understand why there are so many different design ideas out there, because they are all different ways of trying to achieve the same process, but it is necessary I think to fully understand the process that one is trying to achieve to understand why something may or may not be working the way you thought it would.
Edit to add, Dynamodan, I had to give you a shout out too because you comparisons of the different types of fuel that already have oxygen present and the chemistry aspect of it was very interesting indeed!
So again thank you all for taking the time to write, and again, many thanks to all who have contributed to this thread, my hopes are that long after I get my gasifier up and running, some new builder in the future might reference this thread to learn as much as I have.
I haven’t made much progress on mine since my last leap forward a couple of weeks ago. Other projects crowding for my attention and a stomach bug have slowed me down a little, but I am looking forward to making a couple more modifications on mine and running another test in the next few days.
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Here is another personal use DIY gasifier reality Derrick.
With the internally made larger volumous made gasses they actually self-pressurize. Continuously. And self-pressurize lot, until the driving force internal heats bleeds off.
You can see this in many videos. Blowers shut down changing over to engine starting. Whole gasifier becomes a smoke puffer out any, and all, places possible. All experience this when gasifer operating.
So how could it ever draw in air for the air nozzle jets?
By letting-out/drawing-out the produced gasses at a greater rate than they are being produced.
The W.K. guys monitor internal pressures at 2-3 places. Learn to operate and diagnose by pressure change differences.
Many historic system diagram pictures show at least two points of pressure monitoring.
The India Institute of Science CPGL shows always using six channel systems pressures monitoring.
And one commercial system: PowerHearth I am reliably told does not just internally many places pressures monitor, but uses pressure balance changes for valving controls.
Another in-use factor to have to juggle for best performance results.
Ha! Pressure taps clog easily in gasifiers!
Temperature probes soots collect, insulating themselves. Or long-term exposures overheat and burn out.
C’s, H’s and O’s understandings is just a beginning.
Steve unruh
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In H, thanks for the input, you wrote that well about the presence of oxygen in the wood, … start the process with some concentrated heat, and then the gasification process runs and the product of this is a very calorific wood gas, that’s the goal of a good gasifier,… … if the wood were not moist and if there were no heat losses. We are trying to get closer to this ideal gasification process with the construction of the gasifier, heat exchanger, insulation, dry fuel, this is how minimal water is removed, minimal heat is carried out on the cooler and on the surface of the gasifier, and thus minimal air is supplied to maintain the process,…and thus the dilution of the resulting gas, that would be also the key difference between the gasification of wood and the gasification of coal, in which there is no oxygen and we have to introduce it into the process mostly with air, but also with water, and this gas is inappropriately more diluted and less calorific than gas from wood.
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