stoker-man wrote:I can't see how wet/damp coal fines could cause a crust on the plates. ???Maybe a poor grade of coal???
I can see how waste oil could coke up and cause a crust, but In all the years I've used it in my underfeed stoker, I've never had any buildup on the tuyeres until I played with some wood pellets (creosote crust in the bottom of the pot and clogged some of the air holes in the tuyeres, but my air was misadjusted for pellets, which didn't help). I only switched to TSC mineral oil because it's cleaner to handle and being lighter, migrates through the coal much better. Perhaps the air setting is really out of whack and causing burn-back into the screw? I really have no idea.
I've burned some wet coal and never had an issue with that causing any crust either - and this is with bituminous, a coal that as it burns releases tar and cokes and has a high hydrocarbon content compared to anthracite.