my downdraft central nozzle failure again
I wonder about the choice of a central nozzle vs a ring of nozzles. I hoped that the central nozzle would be easier to build than the ring of nozzles, but the heat that this type of nozzle must support seriously complicates things . I’m considering building a water cooled nozzle or opting for a nozzle ring. your suggestions are welcome
Please excuse if you have already mentioned it , what material is your nozzle made from ?
I looked to see if you had any photo’s of this build but couldn’t see anything could you explain to me a little more ,you say its a central nozzle is it vertically pointing down from above or horizontal from the side .
If its of any use to you for the low cost of the Hexoloy tubes you could try testing it in your build , save you having to change anything apart from mounting it inside of your nozzle pipe .
Dave.
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Hi David
it’s a central nozzle that points vertically downwards, made of stainless steel. thanks for the suggestion, I might try the Hexoloy tubes one day maybe
I built this new nozzle. I will test it tomorrow. it is cooled with a liquid… I can’t wait for tomorrow
the coolant will be stored in the small container that communicates with the space between the two concentric pipes
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I just had a thought, with that style nozzle, liquid cooled, would there be a way to catch the tar in the hopper and feed it directly down the nozzle into the firelobe?
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Marcus, my idea is to test motor oil in this nozzle. the oil vapors should crack in the hot zone and the liquid oil should cool the nozzle, at least that’s what I hope
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Marcus you could do that theoretically using a venturi in the air intake pipe connected to the gutter. Main issue would be it cooling down the reaction, and it would be hard to meter the tar to prevent that and it could clog the lines.
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I would think that tar vapor would be better than tar. My WK Gasifier already does comsume tar that makes it to the firetube. It gets sucked in as tar fumes and pass through the hot charcoal lobe and is cracked into good gases. The extra thicker tars just gets collected and dump out with the extra water. You just can’t convert it all.
Bob
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Bob my gasifier runs on coal, it does not produce tar
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Sorry I forgot you run on coal not raw wood.
Bob
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I tested the new nozzle today. I never managed to light the gas. everything seemed normal. the hopper was slightly warmer than usual (probably due to oil vapor rising from the cooling oil bath.
I don’t know why the gas didn’t turn on, do you have an explanation?
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Is the oil inside of your bath inside of the Gasifier from the very start ? or can you pour oil in once its up to temp ?
I have only really let oil into my gasifier one the engine was running so maybe re think how you can load the oil in once up to temp .
Dave
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David, the oil bath is in the hopper of the gasifier and it takes a while for the oil to start smoking. For me
the oil bath nozzle seems to resist the high temperature well. For the moment the oil smoke is dispersing in the hopper. I plan to channel the smoke into the nozzle. but I hesitate to make this modification, I fear that the overheated smoke will burn in the nozzle. What do you think?
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In the past when i dripped in motor oil you could see it vaporise so fast and ignite before it reached the coals , i did not really do too much after that with waste oil due to worrying about any oil running out of the gasifier and onto the ground , maybe i will try again when i get a chance .
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I installed an iron pipe in the ash pan of my gasifier to supply preheated air to the bottom nozzle. Would you recommend using Teflon to seal the plumbing threads in this area?
I fear that the Teflon will disappear, because of the heat, and thus free up a space through which the air could infiltrate.
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Depending on the location, maybe a graphite type grease.
And thread it down very tight, the threads will act like a labyrinth seal. This is why I like plumbing threads, they are tapered.
Edit: I believe Tone made an ash cup for ashes to build up and seal the threads on his.
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I never use any sealant threads on hotest parts. Like Cody sayd, threds seal plenty enaugh for the purpose.
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Labyrinth seal was a new one to me Cody. I had to look it up. Old dog-new tricks.
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Stephen Abbadessa put that one in my lexicon, I think for his little 2" pipe cross draft gasifier.
Edit:
I’ve never made a Constance but I honestly should, and see if it can power one of my sub 100cc engines.
By the way this gasifier according to Stephen has been run on wood pellets and his size of chips.
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I tested my gasifier again today
internal view of the gasifier. The curved pipe feeds, in air, the central nozzle
ignition of the gasifier
this is what my charcoal looks like
the charcoal ignited quickly but the gas never ignited. thick white smoke was coming out of the gas pipe which did not want to burn. My coal may be too wet or too much oil vapor is mixing with the gas and preventing ignition?
Do you have an explanation?
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