Here is another option make it a square shield and a pipe inside.
Now that I really like. Very simple way to add some mass. I think I will still go with a double flute just to keep this build as simple as possible but I can really work with this idea.
Thank you Bob
I wonder if just laying down some weld around the nozzles to make it as thick as you want would work. You could even lay down some fins between the nozzles to dissipate heat?
Yes Cody the double flute is a must in my way of think now. @KristijanL proved it in the single flute design, doubling the flutes and drown draft gasifer will definitely work with this design. I think you can run any size IC Engines with in reason, because of the amount of charcoal that would be consumed for every mile you would drive or with every KW of power you would be generating power.
The important thing is getting the high melting temperatures of heat away from the nozzles area and dissipate it into the metal mass. Let the slag form to protect the nozzles and down below to be cleaned out or carried away with the ash.
Bob
That is another great idea Don. Great input.
Bob
I was thinking of tapping the holes to put pipe nipples in place as stand off consumables.
I like to design gasifiers that can withstand the worst case scenario, dry charcoal with no exhaust or steam injecting. The gasifier MUST withstand this otherwise its just a gamble of “will the gasifier overheat today?” everitime you fire it up.
This sayd, let me add what others have sayd. This design has NOT yet beed made. Its fair to asume it will work but in contrast to a true flute nozzle gasifier it has a big disadvantige. There will be no slag and ash acumulated on the flute as it is 90° rotated. So it is even more important to do things right!
If there is absolutely no other way l wuld go with Dons idea of “3D printing” metal on the flute with a wealder. Remember, its not just mass thats important! In the end heat has to go somewhere and if there is no solid connection to the incomeing air it will build up to a point where it will start to oxidise, burn away.
I wuld reccomend calling a machinist shop. Thick walled pipes like this are usualy feedstock for latheing etc, its where l get them and they are the same price as every other black steel part, around 40c/pound.
If even this doesent get you the pipe, l wuld think of building one.
Make 2 rings out of thick steel, then roll a strip of thick steel around and weald strong and thick together. Now, doing it this way you can easyly add finns inside too!
A bit obscure . . . but then maybe not for some.
Rifle barrels.
The competition guys shoot their out to no longer useable.
You’d only need one. Then cut to lengths.
My adult shooter nephew just retired out a thick barreled Sako. Chrome moly to S.S.
S.U.
Heavy duty bull barrels in stainless can be had for decent pricing right now depending on platform. I paid 280 for a precision barrel on my ar long range coyote remover, much cheaper options are available
I found a source on eBay for a very thick 2"id tube. I think it was 9 or 10mm wall thickness for 80 bucks, 48" length.
If I abandon double flute and go for a Svedlund air intake then I know what I’m welding as a heat sink on the tip of the pipe.
There is one thing i don’t think has been mentioned yet , but the flute nozzle i have used and the flute nozzles i have read about have all been used in the vertical position facing upwards and allowing a mountain of slag to build up around the flute holes and helping to protect it , so in my eyes i see the holes pointing more to the horizontal might not be as well protected as such .
I guess until its been tried and tested we wont know for sure
Yes thats what l ment on my previous post about them being 90° rotated. This is why l think its essential to put effort in making this right.
I do apologize Kristijan i must have missed that bit of your post , i think that’s my problem when these postings go back and forth and i tend to read them after just waking up or last thing at night , my excuse and i’m stickin to it 
Dave
You and me both my friend l try to make my self at least a bit usefull by posting before l get out of bed or while atending the crapper, so take my thods for what they are worth
Do you know where that name came from? I read somewhere that it was the last name of an Englishman who invented the porcelain toilet and his last name was Crapper and it was stamped on every unit that was made and when the American GI’s were stationed in England during WW1, they saw that and the name stuck. For what it’s worth.
Don,
You are a very knowledgeable guy. Here are more Crapper details.
So that being said Kristijan, so then what protects the nozzles in a down draft firetube? Mass of steel shielding that can dissipate the heat or insulation around the nozzles to protect it against the heat of the white hot charcoal. There can be a little slag build up but not much at 90° nozzles. The other protection is water vapor and the hotter the better. Or exhaust vapor from the engine I do not like this.
How about pointing the nozzles downward since the air is going that direction anyways in a down draft gasifer. The charcoal does not need to be bake out of any more tars that has been already gone.
So mass shielding is what I am going to try first with water vapor into the nozzle.
The other is a water jacket flute tube. I am running it though my head right now as I am writing this, hopefully something will come to my mind how to build it and weld it up. I want it to work on convection with the water going through small radiators like on a motorcycle. I found some for free.
Basically Heat on steel is the enemy causing metal and weld failure, but high heat on the charcoal is the producer of good burnable char gas.
Bob
When I get my paycheck this week I will order some heavy duty DOM tubing for the downdraft experiment. I’ll do as Kristijan said and just make the pipes a friction fit for now. Tubing has a 9.5mm thick wall
I think the first test will be with engine grade sized pieces of charcoal and then with some verious sizes no bigger than the average fist and no smaller than minimum spec engine grade. I’m starting to wonder if I should expand the burn tube diameter to 10" if I’m going to use bigger pieces of charcoal. I can always make it smaller but it’s harder to make it wider once it’s already covered in refractory.
Also when I build the unit I will test to see if it can run my 4.3L Sierra using the same dimensions.
What size holes should I drill out for the flutes? 10mm? The intakes will be open ended so I won’t have the air hammer effect that others have experienced with a one ended flute.
I think the first test will be with engine grade sized pieces of charcoal and then with some verious sizes no bigger than the average fist and no smaller than minimum spec engine grade .
I would say do not waste your time playing with the size of the charcoal stick to what we know works well anything up to 1 inch works great , golf ball size upwards to a fist is allowing too much space between charcoal allowing ratholes a clear pathway out and shorter run times due to less dense fuel .
As always just my thoughts .
Dave
The 9.5mm pipe sounds magic! Whats the diameter?
For refference, on my 2.3l Mercedes gasifier l had 8 8mm nozzles (not a flute gasifier) and l had good resaults. You dont wanna go too big, you want a bit of a “cutting torch” effect to push the heat away from the nozzles.
What Dave sayd. Fist size smells of danger. You can and shuld go larger thain engine grade with a downdraft but the great thing about engine grade size is it is bridgeing free and flows le water. Going too big can form bridges.
