Hi Steve, also go back and look at the cut in half gasifer that Joni provided us to look at. I have snap shot the photo and zoomed in on it. His welds are holding on the part that I can see and he said the gasifer was still operating when he replaced it. If you look closely and study the heat patterns on the metal you can tell this was one very hot area. The bottom of the gasifer barrel has insulation 2 cm according to the diagram with a loose plate on top no welding there. The side of the barrel has
2 cm insulation and a inside shielding around it. This has no welding that I can see attached to the rest of the gasifer. It just fits around the outside of the bottom of the firetube preheater on one side and the bottom of the hopper gas out side. This allows this super hot area the expand and contract with out causeing cracking on the important welded joints. Behind this is more insulation going all the way up to the tar gutter. This stops heat from transferring up into the hopper or bunker area. At this much cooler area is where it is welded to make a complete seal for the gasifer unit. The Gasifier firetube is hanging from the weld tar gutter and can now expland and contract millimeters up and down in and out freely. The reduction plate sits in a grove at the bottom of the fire tube and seals up with ash like most other gasifers, and adjustments can be made here if need.
Now how the hopper or bunker makes the transition in the nozzles area not really sure may be cut the metal and bend shape it and weld it back up. I know I could do it this way and put nozzles in and build the heat cowling around it weld it up. With the way it is done it can expand and contract also.
But with this new method putting a nozzles pipe ring in, this is much easier to install and will receive more heat on all sides, which is very good. I could still make the smooth hopper barrel to fire tube transition with nozzles coming out this would create the hot gases under it, that Max Gasman talks about.
My conclusion is this if metals can expand and contract freely they will not crack as easily. And I am pretty sure I see this in Joni’s build. I like trying to figure things out. I have spent about 5 hours studying this if I am wrong oh well no harm done. It is fun and I like a challenge and a mystery.
Bob
Edit: Hi Joni this is also linked over on my Barrel in a Barrel in a Barrel thread. It was supposed to go there. Thanks for all the help on this I appreciate it very much.
Bob
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