Its now a week since the boron carbide nozzle was inserted and thats 21 hours run time so far , no idea the state of the nozzle yet , but one thing i do know is that the shut off tap at the bottom of the tube is cold to the touch after 3 hours run time , so that means its still intact and working very well .
I had a message from my supplier of the tungsten carbide hiding away in my inbox that i missed telling me they only had 10mm bore and did i want that instead , so that means i waited all this time for nothing ! i was expecting it this week as well ready to swap out when i took the boron carbide nozzle out next week .
Bruce do you have the link for the half inch ID bore you said you looked at ?
Cheers Dave
I have long waited if somebody will start blasting charcoal from a distance of >1/2" from the glowing surface. So far it has only lead to sceptisism and denials.
Thanks Bruce more or less the same as the ones i can get from ali express, forget the second one with the plastic cover and thread though
Max if i knew what was happening inside while running i would be a happy man who knows how far its blasting too , but it seems that its far enough away from the nozzle and far enough away from the base , and so i’m happy for now with the results .
Dave
Max I would like to explain a little from what i have found over the past few years , on first light up from filling i always got good gas within a few minutes , but after that i noticed that always lighting was taking longer and longer to get going and also longer get a good quality gas ,it was then when a few of us were talking about how on fresh charcoal they got faster light up times and better gas that i started taking more notice of what was happening to my setup and because my gasifier at the time was a 210 litre drum it was not possible to run it right down and reload with fresh charcoal that in a small unit is easily done .
What i did find out though with a vertical facing nozzle from below on first light up was as i said a very east fast start up and after that longer and longer , it was then i noticed that the reason it was taking longer to light was due to the fact that there was no charcoal anywhere near my nozzle , it had made its own void where nothing seemed to fall onto my nozzle , at least thats how i see it .
Now when i start up i lift the lid and do what the wood guys do , i gently poke a long bar down in the direction of the nozzle and as i get close i suddenly see the level of charcoal drop , i then replace the lid and light from below and it lights up straight away with a strong bright glow and good gas within a few mins .
Nowdays i run my gasifier for roughly 4 weeks@ 4 or 5 hours a week day before i run it down till the gas stops , then the next day i tip it over i remove and slag build up and decide if the nozzle needs replacing or not .
I had also read post from you and others talking about the birdcage and a bell type arrangement to keep the char from the nozzle tip and was myself going to cast a bell type nozzle , until i came across this .
Your system is blowing vertically upward with the nozzletip in direct contact with the downfalling glow?
Developing a lancet-like cavity above it? Naturally.
The opposite, blowing downwards from the bottom of an intensionally developing funnel-like ~60 degree cavity with fresh char is the version I was proposing.
That way one can regulate how high the nozzletip is above the mouth of the burning cavity.
The 60 degree cavity developes as char flowes downward past a large enough funnel opening or tube end.
The “bell” or an upside-down funnel can be sheet metal as they are not exposed to the fire or glow. A large enough 3 — 5" pipe can also be used, and transports the gas out.
The hanging down nozzle tube can be adjusted from above at any time.
To above comments:
1: a working nozzle = a good nozzle
2: if you poke in the nozzle with a welding rod, when running, and it melts, then it is hot…
3: if its to hot your ashes will melt and form clumps around your nozzle tips
4: Those clumps prevent a good gasifying from the new charcoal to come ( the new fuel adsorbs the heat ), more heat stays at the nozzle tip…
5: IMHO pointing the nozzle downwards and having a ash melting temperature is more likely to fail.
6: IME a smaller nozzle gives more blast but also more temperature.
I am waiting until i see someone using this downwards funnel like cavity, then study the results of it… meanwhile i keep it simple
Many things i learned by listening and by doing… listening to the older’s, doing by burning my fingers
Since i did not change my MOA and don’t see the need of that , i started to construct (in my mind) a working system where as i can easy empty the old charcoal without having to replace the whole hopper filling.
Therefore i will follow some idea from *** can’t remember his name but will update this later he has some nice builds , and extract my gas just below the hopper.
My grandpa teached me to clean out the woodstove daily… so why would i not do the same with something as important ?
With the gasifier, This helps a lot to improve startup time , also avoiding unexpected downtime , no repair to wait for cool down
Checking the nozzle daily , clean the filter daily
Oh i fully agree with you Koen , and its because of those rules of keeping it cheap,simple,and as easy to operate with as little fuss as possible that i am able to run for a minimum of 4 weeks before i have to lay a finger on it . my drum has to be the size it is simply because i want a run time of at least 5 hours , and that is why i keep on searching out the holly grail of nozzle material , and its getting closer to the point now where i hope to be able to only empty the gasifer to remove clinkers and slag build ups . , another 2 and a half weeks and i will know for sure how well my latest nozzle has help up .
Dave
The so called tungsten carbide nozzle arrived yesterday , i say so called because as soon as i took it out the container it was in i could feel the weight difference from my old piece of tungsten carbide i got from the UK , so i sent the supplier a message asking him if he had made a mistake and sent me a boron carbide by accident , he has just replied asking me to please try it and if it does not work as i had hoped he will refund my money , he also said that it was indeed tungsten carbide with a mixture of boron and that is why it is lighter ! hmmmm we see .
Anyway the old boron carbide nozzle is still in and running so i am in no rush to test this one out just yet till the old one fails
The Boron carbide cost about $14 and the so called carbide/Boron nozzle was $24 .
I think its got the better of me now and i shall be taking out the Boron nozzel so i can see how its stood up to daily runs for the past 3 weeks , plus i shall be able to compare the 2 side by side as long as its not destroyed too much .
Please forgive the newbie question here. Why is graphite not an option for a nozzle (albeit it’s brittle and may present challenges to seal against the reduction vessel wall)?
Thank you for your reply, Koen. The reason I thought of graphite is because it’s the material of choice for crucibles to melt many metals. It’s typically in direct contact with flames, and in the presence of oxygen ( not liquid oxygen). It’s not particularly expensive and can be found in various sizes, and very machinable. Am I right in assuming that the fact that it does not conduct heat, is an advantage for not robbing the heat out of the system?
