Upper. And that short line could be a factor. But let’s think about it straight engine sucking vaccum vs. Ventrui vaccum in the end of a tail pipe. Straight sucking engine is greater even with some air mixed in.
Bob
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Bob, maybe it would be possible to still eject with venturi, but use the gasifiers incoming air.
Like those valve cover breather catch cans.
A venturi line from the gutter to a tank, with the intake line being either baffled away or simply high up in the tank. This way heavier water will settle in the tank and any siphoned producer gas goes through the nozzles.
This also would settle my worries during shutdown, no woodgas seeping out of the tailpipe and letting oxygen into the hopper. When the intake is shut down the system is closed from outside air.
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I decided to just stick with the standard WK style hopper with condensation tar / water tank. It work good.
Bob
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Hello Trigaux, if you review this topic, you will notice a small pipe installed on my gasifier from the top of the condensate tank and also on the water-cooled exhaust pipe as well, … I tried suction of steam and gases from the top of the gasifier tar gases, which, however, give a rich and powerful gas, so I abandoned this process. Condensation of water vapor should not be too intense, as superheated steam in the hot zone also forms a good gas. The gasifier is well insulated and heated to the top with the resulting gas, so the real hell is inside, pyrolysis already stretches high above the hot zone, which creates a lot of gases, which I do not want to lose because I need them in the hot zone. 
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Raw wood gasifier, additional cooling pipes for condensation above, added labyrinth for better interior heat preservation and at the same time a trap for ash and soot,…
comments are welcome
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I definitely think cooling pipes for the hopper top will aid in removing water. It may help control the chaotic pyrolysis that classic Imberts apparently suffered from.
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I would put a soot/ash trap clean out hatch door on both sides for easier cleaning out of that area. What will the spacing of the baffles above it? Hopefully more than a 1.5" so charcoal will not get stuck in that area.
I like the lower hopper heating and the upper hopper cooling tubes for removing excess moisture.
Are you going to insulate the bottom part of the TS (Tone Sustaric) Gasifier?
Bob
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i was thinking maybe build cooling rail farther away from the hopper, in a cooler location,and pump the hopper steam air too the cooling rack and back too the hopper might be even better.
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You do not want to cool the tar/water vapor down to much just enough to drop the water and tar out. If you cool it to much the pipes will tar up. Keeping the pipes as vertical as you can is best too for the tar to flow downward into the condensation tank. Angles at 45° bends is good, not 90° with flat spots.
Bob
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Good thinking Bob, limit the horizonal tubing , or it would soon tar up before it makes it too the drain tank.
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Bob, I don’t think the bits of tusk will rise up the wall, but will fall to the bottom, there is considerable volume around and around the inner cylinder, even 1 cm of space to the larger cylinder represents a large area and a slow flow of gas, only fine ash will rise and coal dust and I assume that some of these particles will be caught on the way down into a wider area where the speed decreases and changes direction… it would definitely be good to have more cleaning openings
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I think the labyrinth will not have a noticeable effect on heat retention as there is no significant exterior heat exchange surface area added or removed. In fact, the weld seam for the inner baffle that connects to the outer casing will just conduct more heat away from the interior of the system. The gas traveling in the inner mantle is only in contact with walls that have more of the same gas behind them. A ‘‘plus minus zero’’ like we say in Finland.
Further on, gas in the narrow labyrinth passages will be moving faster than it would it the single combined thickness layer, thus particulates are more likely to overcome gravity. Bernoulli’s principle in effect.
If you really want increased ash and soot trapping and output jacket gas dwell time, angle the output pipe to draw out the gas tangentially to induce a cyclone filter effect in the output jacket. Compared to that solution the labyrinth adds more flow resistance drag to the system and is another area to clean out, and a thin ring shaped one at that.
Keep It Short and Simple, I say. And lighter, cheaper and easier to fabricate for that matter. Your system has great preheating already by the way, some of the best I’ve seen in fact. I have to congratulate the smart intake design!
Going through the principles of system insulation:
1: Using material with low thermal conductivity.
2: Decreasing surface area to reduce ambient cooling.
3: Preheating. While not technically insulation, it has the same outcome of retaining more heat at a time inside system by moving waste heat back towards the middle of the system where it can do work. Also remember the effect of countercurrent heat exchange for maximum preheating.
Lastly I want to point out how the output gas makes contact with the bottom of the condensate gutter, I believe this heating boils some mist back into the hopper rotation. Water doesn’t need to reach it’s boiling point to turn into vapor, it just doesn’t happen that quickly. This is why the condensate gutter and collection tanks should be kept cool even after condensation has already happened.
I hope my criticism is constructive and not too negative. You are a great DOer Tone and deserve all the due respect.
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Hello Antero, welcome to us, from your words it is clear that an expert is speaking, I am happy for criticism and different views, because I am often like a harnessed horse with side screens next to my eyes. Thanks for the comment, I will write something else in the evening.
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Welcome Antero. You are obviously well versed in wood gas design. Please stick around and contribute more.
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Thank you both for the warm welcome. I’ve been lurking here for a long time, over a year now - lots of reading but little time for writing comments, trying to change that now.
Tone, never feel bad about the ‘horse with blinders’ feeling. It’s better to think something up in an effort to improve a system, than not to think at all. The best innovations come from thinking outside the box.
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Also Tone I want to give some food for thought: I’ve been thinking of improved preheating for a similar system with a bottom air intake.
It’s essentially a bucket that the gasifier sits inside. A thin open top sheet metal shell to guide intake air from the top down the sides and along the bottom of the hot output jacket portion of the system into where intake air is drawn in. The paths of air in the shell and gas in the output jacket go opposite directions for optimal countercurrent heat exchange. The shell would also insulate the gasifier somewhat from touch (safer for bush fires) and wind cooling.
The shell sits only a bit away from the gasifier, fixed into place around it using welded tabs. Gasifier mounting struts can simply go through it as the shell doesn’t have to be particularly airtight or structurally strong and can have cutouts or panels for performing operations like lightup and ash cleanout. The ash cleaning cutout would also work as a drain for any rainwater.
This shell could also later be filled with an insulator like rockwool or fiberglass if needed.
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I’ve occasionally seen you Like a comment here and there, I was wondering when you’d start posting! A belated welcome to the forum Antero.
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Yes , what Cody said.
Welcome Antero 
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Hello Antero.
If l read you right, l had versions of this on a couple of gasifiers. Having been building in trunks mainly, l had to use every possible way to get rid of some heat. My latest Mercedes gasifier (or was it swcond last?) Had l think at least 3 or for lairs like this, welding was a pain and l even missed a full section, about 8" of weld right next to the exit of the heart 
miraculously, the thing ran quite some time with a 8" long slit pouring air right in the superhot gas.
Anyway, sorry, got carried away here. Carry on…
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