Right, with a separate valve I can shut off the air supply to to the upper nozzle manifold, but it seems I never use it. There’s no need to. During winter it frooze in open position from tary smoke backing out the nozzles and I haven’t touched it since.
Right again. No grate. Works pretty good. I have to be careful though, not to pull too hard too long, or I lose too much char into the cyclone. Sometimes even more than the cyclone can handle. I always flush some char from the rear tank.
Over time I get a bottom sediment of sandy ash/slag in the gasifier. It has to be emptied manually, but I’ve done that only twice in 7,000 miles.
If I ever build another gasifier, the internals will probably look pretty much like a WK. I’ve been kind of reinventing the wheel, but from the Imbert layout starting-point. I don’t regret it though, because I learned a lot doing so.