A fume incineration system for an industrial process site such as a paint-drying oven (10) producing a combustible effluent. A first duct system (34, 38, 42) conveys effluent to the incinerator (14). A second duct system (44, 48) conveys incinerated effluent back to the site. A third duct system (52, 56) conveys part of the incinerated effluent to an atmospheric vent (57). Control dampers (50, 74) in the duct systems operate sequentially to handle temperature changes, and control damper (84) controls system air flow balance. All ducts and thermal devices except the incinerator are located in an insulated housing (12). A thermal incinerator (14) having an internal preheater comprising an annular tube bundle is disclosed.