The retort system has both double and single surface air and/or gas heaters heated by the heat carried off by the products of combustion. The double-surface heaters are in this class called recuperators, the single surface, regenerators.
SEE OR SEARCH THIS CLASS, SUBCLASS:
122, 123, 130, 132, 140, 141, and indented subclasses, 146 and 148.
SEE OR SEARCH CLASS
201, Distillation: Processes, Thermolytic,
15+, for a carbonizing process including burning a product of the carbonizing step and recovering heat from a product by indirect heat exchange, and subclass 37, for a process in which externally produced combustion gases are passed through the retort.
