Looking great Tone, i really admire you work!
I like your vehicle hoist! I think that maybe Jakob is the only other woodgasser that has one? Wish I did, then I wouldn’t have to worry about getting up off the floor.
Looks good, Tone. I still wonder how time works in Slovenia. 48 hours a day?
You mount one of those little Harbor Freight hoists in your rafters Don and wear a sturdy belt. You only have to be careful about flipping upside down.
I know you are not fond of much praise Tone but that is a masterpiece.
I am still thinking a bit about the construction of a wood gasifier, here is a sketch where the interior would be without constrictions to the bottom nozzle, and the air would travel from the top and be heated by hot gas on a large surface, the nozzles for charcoal formation would be placed widely on the inner surface, well, the air here would enable pyrolysis, and the remaining air would go down through the vertical hollow grate, where it would be additionally preheated and thus superheated it would be blown onto the lower nozzle in the middle. condensation of water vapor would take place on the hood, where the surface area would be increased by WK-style tubes. The surface would be insulated, so all the heat would remain inside, necessary losses would only be due to the condensation of excess steam. Any comment?
I was always under the impression that gas was created in an oxygen starved reduction environment, but here it looks like that is the only place where oxygen enters this system. Am I missing something? I wonder what kind of turndown ratio or flywheel effect this would have?
EDIT: I looked closer and saw the higher nozzles arount the fire tube so disregard my former statement.
How I imagine gasification:
- coal gasification is carried out at a high temperature, which is achieved by incomplete combustion of coal, where CO is produced, this is only possible where oxygen is supplied to the coal so far from the exit that there is always an excess of coal during the path of the gases and thus it is impossible complete combustion or the formation of CO2
- if the temperature is high and there is not enough oxygen in the hot zone, the coal has the condition for gasification, which is further deposited in the system as soot
-if water vapor is introduced between the hot coals, this is good for reducing the temperature, and since energy is used here, the splitting of water into hydrogen and oxygen and a stronger gas is formed
- if rich tar gas is fed into the hot coals, it most likely breaks down into methane, which also cools the hot zone somewhat
- temperatures are supposed to be lower higher up, pyrolysis or coal cooking is supposed to take place there, coal, rich tar gas and water vapor are supposed to be produced here
- water vapor is the lightest gas, so the concentration of this gas is highest just under the lid and the condensation of excess water vapor is carried out under the lid
I hope to entertain you at least a little with my posts, winter evenings are long and it’s nice to think about a warm wood flame. Well, let’s get to work, … the last sketch of the gasifier shows a design where the upper ring of air nozzles is placed right on the walls of the funnel, so the wood can slide down unhindered to this place, where hot air is supplied, which enables burning and thus raising the temperature for the course of pyrolysis and also partial reduction of gases. The amount of air depends on the negative pressure in this area, and the negative pressure depends on the gas consumption and the density of the coal in the lower part, if the density is high below, the air intrusion at the lower nozzle is large and this causes the gasification of the coal below and the withdrawal of ash, thus creating a space for new fuel.If the charcoal at the bottom were consumed too much and an empty space was created, the oxygen supply at the bottom nozzle would cause the gases coming from the funnel to burn, and this would prevent the spread of tar throughout the system. The system would, due to its wide range of upper nozzles, without large narrowings below and the large surface area of the vertical grid enabled the supply of a large amount of gas, as well as stable operation at low flow rates. That’s how I think now.
Okay Tone, I see by this design you are trying to prevent bridging of the wood in the hopper as the wood is pyrolysis and moving down. The upper air nozzles in a larger diameter can only penatrate so far into the center before be sucked downward. I am not sure of the diameter size of the upper nozzles anything pass 14" with the larger WK type nozzles will still need a choke or restriction area if running on raw wood. Smaller hole nozzles might be needed to accomplish the more penatration to the center at the upper nozzles ring of the firetube area. The charcoal reserve below the restricton or choke needs to be large enough to keep up with the lower nozzles Charcoal consumption like you said. Basically I like this idea you have come up with the hottest area at the grate tubes heating the incoming air before going out of the upper and lower nozzles.
I think he is letting each row of nozzles progressively make the charcoal, and the lower nozzle is to clean up a tight char bed and also burn away tar gasses. The bottom nozzles substitute the restriction.
In his current build the first nozzles to get air is the bottom Stand Pipe with nozzle holes in the side, and it goes progressively up.
His new drawing shows the upper rows get air first and the final nozzles, aka the stand pipe, gets very well preheated air thanks to his tubular bird cage grate.
It also means the gasifier could be mounted sitting on a truck bed or as a stationary setup
Tone I like the design, a couple months ago after I read your tractor build I a drew up a sketch on computer to see how to use the water heater tanks and stuff I have, and a couple days ago I started to build it, every section is flanged so I can change things if it needs.
Enakomeren pretok goriva skozi plinifikator je zelo pomembna stvar , še posebno pri stacionarnih enotah brez vibracij, tukaj sem poskušal narisati skico , kaj se dogaja v taki zasnovi vroče cone . Ko se pojavi most in pod njim praznina , se spremenijo tudi tlačne razmere , zaradi tega prične dotekati na zgornje šobe več zraka , kar povzroči zmanjšanje kosov v bližini šob , pravzaprav to pomeni izpodkopavanje temeljev mostu in zanesljivo rušenje oboka.
Hello Dean, you probably intend to vent the gas below through the grate through which the lower nozzle is installed, which in my opinion is not the best solution. A better option is to replace the grate with a plate that has an edge around it to hold the coal, into which the restrictor tube will be immersed, and the gas will move to the side through the fine coal and at the same time carry away the ash. It is also a good idea to place a small ring around the nozzle below, which will hold the cone of ash next to the nozzle stem, and this will prevent the nozzle from overheating.
do you want to explain that the soot comes from the thermal gasification of coal? (in the absence of o2)
thank you Tone for your explanations all this seems very sensible. how do you proportion the size of the top nozzles with the bottom nozzle?
I envy your insight
Hello Thierry, I use nozzles with small openings, 4mm at the top, the bottom one has a 6mm inlet hole, and the top one has 6 4mm holes. Kristjan once told me that the correct idea of what is happening in the gasifier is when we think about a full gasifier. Below is small coal mixed with ash, higher are somewhat larger pieces of coal, even higher still larger… up in the funnel there is a large expansion of pyrolysis gases, which raises the pressure in this part, which extends evenly until the narrowing or to more condensed area, if we descend lower with the flow of gases, the pressure also decreases due to the resistance between the pieces of fuel and the narrower section, thus we reach the lower nozzle, where the pressure is already quite low, here the difference between the pressure of the outside air and this place is already relatively large and so the air blows through the nozzle to a considerable extent, we must not forget that here all parts are heated and the air is hot, which reduces its density and increases its volume. Now we are separated from the end of the path only by small coal mixed with ash, which is filled in the siphon barrier, so the flow of gases in this part has to raise this mixture and carries away light particles with it.
I am very impressed by the good balance between the two nozzle levels. At first glance, I would have thought that the bottom nozzle was very difficult to adjust. This nozzle would push too much or too little air. the gas would be burned or the ash/coal bed would be clogged
Congratulations again. I’m a big fan of your creations
PS: what is the displacement and the rated speed of your engine?
I’m still thinking a bit about the process of condensing excess water in the gasifier. Considering the fact that water vapor is the lightest gas in pyrolysis and therefore rises right under the hood, … well, I’m already thinking wrongly, the correct explanation would be that heavier gases are more easily displaced to the top. What determines the weight of a gas? The answer would first be its chemical composition and its current temperature, but here things get complicated. Let’s say that the gases above the hot zone are the hottest, that means in the middle of the funnel, but they are slightly cooler near the walls, which means that these gases are displaced from the sides in the middle upwards, and the heavier ones are partly pulled down into the hot zone by the pull of the engine, and partly they warm it up again and lift it up in the middle. If the walls of the funnel are also heated to prevent condensation of water vapor, the buoyancy of the heavier tar gases would really push the water vapor under the top. Well, here at the top, we cool the surface and droplets of water are formed, which collect in the gutter. If I focus on condensation itself, I can see that this is actually a change in the aggregate state of water from gaseous to liquid, and here the volume is greatly reduced (1600:1), which creates space for new gases. This fact and the desire that the condensation zone is used exclusively for the elimination of water, but not for the cooling of other gases, I think that the best method for this condensation in the refrigerator is a “dead end” or “caecum”.
thank you for the nice video…i also like plowing very much, till now with the horse, but in the moment i am preparing a old plow for the motorcultivator, i hope it will work, we have a very hard ground, especially if it is dried out during summer, and a lot of stones- calculated by volume : more stones than earth…
have you used in the video the sheep wool in the filter?
what experiences with it?
is there always the paper filter as final filter?
always interesting seeing what you do!