Process for treating waste feedstock and gasifier for same

A method for processing waste feedstock comprising:

• introducing said waste feedstock into a gasifier having a top, bottom and sides forming an enclosure;
• passing hot exhaust through a plurality of sealed-hollow heating plates stacked vertically within said gasifier, each heating plate having a top surface and a bottom surface and an outer wall, with spaces between each set of successive heating plates forming reaction zones;
• conveying said waste feedstock through said reaction zones, starting from said top of said gasifier and exiting from an exit in the bottom of said gasifier;
• wherein each reaction zone between a pair of heating plates comprising an upper treatment area and a lower treatment area, and said waste feedstock being conveyed through said upper and lower treatment areas to a next reaction zone or to said exit;
• wherein vapors from said waste feedstock are drawn off through an outlet for further processing;
• and
• wherein said exhaust first entering a lowermost one of said plurality of hollow heating plates and moving progressively upwards through successive hollow heating plates in said gasifier until exiting through an uppermost one of said plurality of hollow heating plates.