https://m.youtube.com/watch?v=ROMVJnVgqlk
Bestest video of a wet kiln tire injection setup that I know of. I think this one was in New York and shut down during the 08-09 crash.
Wet kiln means you feed a wet feed stock into a long rotary kiln (ours is 450 ft). The feed is about 35-37% solids and the rest water that you drive off. Considering we put 200 gpm into our kiln some water in the tires doesn't matter.
A dry kiln means you feed in dry material typically through a preheater and calciner into a short kiln (~100 ft). Not driving off all that water and capturing the heat in the preheater means you use about 40% less energy/ton hence other than markets like ours where raw materials costs are super low and the demand isn't comparatively high all of the wet kilns went away during the 08-09 slow down. In a dry kiln they burn shredded tires, medical waste, shredded rail road ties, saw dust, and anything else organic that they can get permitted and cheap to burn rather than injecting natural gas or coal.