[quote=“Tone Šuštarič, post:572, topic:5240, username:Tone”]
an even bigger heat exchanger, which will close with the swirling of the gas above, which will enable the removal of fine ash and at the same time a good heat transfer to the fresh air.
]what do you mean by “, which will close with the swirling of the gas above,” 
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Cody, I don’t have any formula for the diameter of the hot zone, but based on the size of the wood pieces and the size of the engine, I would determine the diameter of the top tube by the WK method, and the restrictor tube below would not choose less than 20 cm. Thierry, I hope the sketch below will help you
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Tone, I want to think with you but you are way ahead, cant keep up 
. When you started with your low nozzle I thought it would only give problems. Now I think, yes of course:smiley:. Like I said, you are to clever for me but I enjoy looking at what you come up with…
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Joep , if a person is made “smart” by writing a few “confused” sentences and a few vague sketches drawn with a pencil,… ??? 
What can I say, the only thing is, thank you for the kind words and praise, which I do not deserve.
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Not really Tone, not only sketches but actually building. Still trying to figure out how your lpg carburetor wirks 
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Joep, if you sacrifice your one working day and make a smaller unit (for your Yanmmar), you will be able to test the operation in practice and quickly understand the operation itself.
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Yes, that is the idea. If you do the thinking I can do the cutting and welding
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At the moment, it is relevant to draw gasifiers, here is a sketch that shows apertures for forced swirling of the gas immediately at the exit from the reduction zone, thus a considerable part of the ash would be eliminated.
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I like that air-transfer port Tone 
, often a problematic thing to build.
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With all the metal baffles in the drawing it looks to me like a place where lots of char bits can get stuck? And how to clean it out? Air hose blasting in from the bottom ash/char clean out hatch?
Bob
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Bob, my assumption is just the opposite, a loose hot zone is formed down here around the center nozzle, where all the coal dust and bits of coal turn into gas and fine ash, which the vacuum of the engine can therefore suck out. A tube is inserted inside the zone to prevent the ash and charcoal from directly sliding through the openings, thus creating a hold on the fuel in the hot zone until it turns into gas and ash. At the bottom of the exit openings, I want to achieve a vortex of hot gases, which would thus throw ash on the walls of the pipe, which surrounds this part and reflects thermal radiation. The hot gases are light and for the most part rise up inside the heat exchanger, well, towards the top they cool down a bit and a small part cools additionally next to the outer wall and thus creates an insulating layer against the outer casing, with less gas consumption this part would be cooler gases due to its greater weight, it would travel downwards, but with a greater one, the gas flow would be upwards and thus the outer casing would act as a cooler…
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Oh okay, in the drawing I did not know it had the bottom nozzle still, now this is making more sense to me now. It is just a simpler design here of what you have designed before. With heat shield reflecting at the bottom causing vortices and no preheating tubes for the vertical grate. All air preheating done above for the upper nozzles.
Bob
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More a general question, since more people use grateless gasifiers. What about clinkers? How do you get rid of them and or how do you prevend them?
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Hmm, the questions are more and more demanding, well, my theory and experience regarding the melting of ash and the formation of mineral solids is as follows… The condition for this process is extreme temperature and the amount of molten ash that remains in the center. If we change this central hot zone into a narrower layer that expands from the center outwards, the formation of lumps is avoided, as the flow of gases continuously withdraws the molten ash through the side openings… I have not noticed any large pieces of clinker on my tractor in the last 100 hours of operation. maybe a maximum diameter of 5mm. 
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Joep, usualy, if the foot is not too heavy and the gasifier is designed right, not much clinker forms. Poking in the hearth with each lightup also helps break any lumps. Also wood species/soil seem to matter.
When l was runing grateless l had to empty the reduction zone about weekly. Hatch underneeth. No big deal.
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Bob, if you look carefully at the sketch, the air is counter-currently preheated at the top and travels to the very bottom, there are pipes installed and welded to the inner jacket, which lead the air from the very bottom to the upper nozzles, but part of the hot air feeds the central lower nozzle. The WK system has something similar built inside,…
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Here I will list some thoughts as I observe and think about the processes that take place in the gasifier. At the beginning, I should say that the total diameter of the holes through which the air enters is only 15 mm, which is the diameter of the water pipe 1/2". The air is distributed in three areas, above in a wide area, where, in addition to radiation from the hot zone, it enables pyrolysis and thus the formation of pyrolysis gases, then into the hot zone, where the coal is gasified and the conversion of pyrolysis gases takes place, and below in the middle, where the remaining fine coal is also gasified and thus the mixture of coal and ash is loosened, which is a condition for the smooth removal of fragments with the flow of gas. Since the negative pressure in the lower part is almost always present, air almost always enters through the central lower nozzle and ensures a high temperature and gasification of the coal and thus also prevents the breakthrough of tar gases. When the negative pressure increases slightly, the central main nozzles start to work , which activate the charcoal in the hot zone, but with an even greater negative pressure, air begins to enter through the upper nozzles, which means that the formation of a large amount of gases begins here, which causes a large expansion and thus reduces the negative pressure in the storage tank. The steam and tar gas rises under the cooled cover, where part of the water vapor and also the tar condenses and is excreted, condensation is better if the surface is cooler and when the negative pressure is lower, or when there is no negative pressure.
Of course, it is very important to maintain a high temperature in the lower part, great emphasis must be placed on the heat exchange between the generated gas and fresh air, here I still have some room to improve this. Let me also say that it seems to me that the upper nozzles buried in ash (boreholes in the pipes) dissipate much less heat from this part, so the pyrolysis and drying of the wood continues long after the shutdown…
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How large of a gasoline engine do you think your gasifier would fuel to run in the 2-4 thousand RPM range?
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Tom, I think this size gasifier would provide gas production from 5 to 30 kW (maybe even a little more, up to 35 kW), this would correspond to engines from 1.0 liter to 2.5 liter working volume. Of course, the output amount of gas depends on the size and type of wood, smaller pieces allow more gas.
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The “development” of the gasifier is apparently not going to be completed any time soon, well, here is one “confused” sketch that probably looks complicated, …
Here, the emphasis is on counterflow preheating of fresh air, which acts as a thermal barrier for the condensation zone at the top, where it enters still cold.
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