Giorgio , Thank you for the wonderful photo’s anyway they do help to explain a lot of what’s going on along with your commentary i can only imagine how fantastic the engine must sound to you .
Looking closer at your nozzle is it around a 12mm the opening ? with a slight downwards angle onto of your reduction basket , so the distance between the tip of the nozzle and the grate must be somewhere around 120mm ?
I ask these questions out of pure frustration from my past downdraft experiments where i think maybe i am going wrong is my reactors are always much larger and i think maybe i should go with a smaller set up and maybe re fill on the fly instead of aiming for 5 hours uninterrupted run times .
Anyway well done as always
Dave
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Giorgio, l dont know what to say. Your gasifiers are art. I can only imagine the amount of thinking behind.
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don, i like more if the horses are fat as too meagre, also for a certain reason i cannot write here…
when we must do plowing here is september or oktober, in our area really hot and dry, so this heavy work with the horse can last only for two or 3 hours early in the morning, after is too hot…
and in this time we have always yet a LOT of stinging horse fly around the horses, so i have always the hands bloody from killing them…in other climates or also here more later or earlier in the year horse working is divertent, but here from end of june to end of october not…but the seed must came in the ground till end of october, later the ground is often to wet for doing this works…so, with the engine i am more flexible , i get the stings and not the horse!
it is only another standing leg, and i can do it alone and need not another person to guide the horse…and such reasons more…harrowing with the horse is easier more speed, the insects cannot sit down so easy on the horse…
dave,what problems exact make your downdraft?.. today, when i am emptying the gasifier, i will take the measures…on my stationary set, my first build, i have running time 6 hours with a 200ccm engine…for tresher and band saw…
all from propane tanks…look on my “transmission belt” thread, …but propane tanks are too heavy for mobile little engines how as for my mowers, so i used there thinner stainless sheet material …less weight and more rust resistant…
downdraft is not dificult from my sight, and for bigger ccm sizes the nozzle problem is easy to resolve with a water cooled one…with running the engine the last 2 days, in one hour the water consume by evaporation is less than a cup, the water tank has 5 liters, so one must not always look if there is water yet or no…
kristijan, the basically design i have found on a pdf for a project in columbia (i have it posted also in my threads somewhere)… this was before i found this forum…made only smaller diameter and less high the reduction area, because of using a smaller motor…and nozzle from side instead of centered from top downward…for this type of nozzle my available material not keeps up…i used the same piece as i have in my forge as nozzle, a cast iron piece with a 30cm or so hole…piece from a old wooden horse cart wheel…the piece what stays on the axle…in the forge with side fire it keeps up excellent, in the gasifier from up to down it melts away…-too big hole and therefore to slow air speed, and also as a newbie i overpulled the system in the beginning , using my forge hand blower, so the complete reduction coal burned away…beginner problems with hopely learning effect…
the other things are combined by obsevations…more confortable clean out instead digging out from the top, the filtering and so on…always also take benefit from the obsevations of the forum members here…great forum, great family…i will say…
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dave, the nozzle hole is 10mm,
nozzle height in center(hole) is 18 cm from the grate,
diameter of the reduction pot is 24cm,
nozzle protruding in the reduction pot is 4,5 mm
inclination of the nozzle downwars is 16 degree
slots of the grate are 5 to 6 mm
what you run with your gasifier? a electric generator or other motor? in what ccm size?
i think it is important to have a very “open” grate, will say a lot of slots or holes, so ash can pass through with vibrations of the motor
important testing a self built water cooled nozzle with water pressure…filling water inside without pressure is not enough, because the welding seams have very small holes-pores what can only be detected under pressure, and this water dropd than somewhere down in the gasifier hearth and makes a mess .
the pressure test is best before the connection fitting -thread is welded on…i knew from my ram pumps that the welds must be tested under pressure , but here with the nozzle i was too lazy, the welding seam looks perfect…and than the unthigt spot was really under the threaded fitting, what gives me a day of additional work to weld around the fiting on the threaded side without destroying the thread, and always testing between…
for the reduction pot can be used also kitchen pot in stainless, best with a bended edge on the upper side…when your wife goes shopping in town, take the pot…and your wife will never have the idea to search the pot in the gasifier…!!!
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Here’s a post with a link to that file.
The post right below it has the drawing I made rounding up the dimensions to inch measurements.
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the clinker from yesterday…
this historic foto was a bit my inspiration…a real beast, how one of our tom´s has said, i don´t remember if it was tom holton or tom collins…?he has worked in his youth with such a engine…
some other fotos…
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Hello Giorgio , I run 8KW inverter generators , running flat out making as much power as charcoal gas will allow the engines to make , in these generators are clone 13 hp GX390 engines .
I have used downdraft units i put together over the years first ones did not seem to make powerful enough gas , i think that was down to too hot of a gas coming out and so i have tried various ways of slowing down and cooling down till i managed a very fast start up time with excellent powerful gas , but then i had runs when i started and walked away and just as i get to the house i hear the engine slow and i have to go back and adjust .
I need to spend more time refining the downdraft for sure ,but i always have my trusty updraft 55 gallon simple fire that once started i walk away (99% of the time ) for up too 5 hours and never have to adjust tinker or mess , and its still running the same Hexoly nozzle i put in the unit in i think it was 2018 anyway its still in 1 piece , but i cant help myself i have many gasifier projects on the go at the moment wood and charcoal , winter and poor health has slowed me down this year but i feel more enthused with new and old members all having fun building there downdrafts units so that is helping me get on with it .Keep up the great work everyone .
Dave
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Giorgio, this machine of yours looks really nice, it certainly works well, the Acme 550 engine is no joke, it already develops a fair amount of power, which is sufficient for any job, the full power probably reaches 10 HP 
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tone, when plowing i used the 1 gear, with the 2 it suffers a bit, and the 2 gear is just a bit speedy…and the ground was a bit too wet and sticky- clay ground, and the plow is a seep turner, what makes more resistance as a flat turner, but breakes more up the ground pieces…
my horse plow is more between steep turner and flat turner, this needs less power for draft…
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dave, maybee the reduction area of your downdraft is too short??
the beauty of the updraft is, one must not calculate the reduction volume, it is from itself flexible and has always enough coal over the “head”
i have had a instructive experience with my downdraft gasifier on my harvester little blue mower…it runs always fine till last year, not likes to start more because of weak compression…so i must grind the valves, than the compression was really strong again -
but it starts well on chargas, runs for some seconds and than stops- my conclusion because of bad gas. (ignition, valve timing ecc was all ok)
what has happened?
because of the better compression the motor sucks more quantity of gas, till there was good gas available from the filter, it runs, and than comes bad gas and the engine stalls…
the reason was that with the stronger suction i got a bigger reaction- fire ball- this goes deeper down in the reduction area, and therefore the reduction was not more long enough.
so i must modyfie a bit my reduction chest with the bypass -anti plugging -slots…
i made it about 2 cm more down, and than the mower runs well again !
maybee this can be a explanation of your problem??
especially with electric generators you have a very high rpm, so a big suction on the gasifier.
ciao giorgio
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Hi Giorgio yes i thought that too and so i made sure of giving it the longest time possible from the nozzle height to the grate (approx 10 inches) with a good depth of charcoal the gas then has to run to the other side of the container furthest away from the nozzle to be taken away by a pipe connect back on its self under the nozzle , imagine the letter S is how the gas is routed along under the grate to help the cooling time .
Hoping to get back into this summer lots to do so i hope to be able to show some of it later on if it all works out well .
Dave
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