That drawing is much better then I expected.
I am going to sound a little bit negative, don’t take it the wrong way. Just suggestions. I wish I had a nice chunk of pipe to work with.
I suspect the chain for the trapdoor is going to get hung up, and it is going to interfere with the flow of the material through the system.
I don’t think your airflow is going to work that well either. The more I think about it, you have like a closed Kon Tiki, which would work good without a top since you keep having to add material to it, but the fire marshall might be after you, and taking the top off while it is running is probably going to have a flame that shoots up. For batch mode, you are most likely going to want the air from bottom to top, or top to bottom.
I am a bit bias. I am very partial to my 55 gallon drum smoker. err charcoal maker because it dramatically reduces the risk of fire. The fire marshall guy was okay with it. It doesn’t create consistent charcoal, because of airflow through it and I start with inconsistent pieces, but it will dramatically reduce the size of the brush pile, and you can sift off the ash, then run your system during the rainier season or after a rain as an open top kon tiki type of system.
Someone did have a huge kon tiki type of system with a trapdoor on the bottom.
Honestly, I might try a closed retort and use the pipe you have as a rocket stove to heat it up. I’m not sure a rocket stove gets around the open flame restrictions though.