Regenerative thermal oxidation apparatus and method

Abstract

An improved regenerative thermal oxidizer ('RTO') and improved method of operating same in order to provide a substantially steady-state flow of contaminant-laden air into the RTO. The RTO includes an automatically-operated balancing valve structure for minimizing pressure variations experienced at the inlet of the RTO. The balancing valve is connected to and provides a selectively closeable bypass path for air flow between the high pressure and low pressure sides of an exhaust fan. The balancing valve opens the bypass path whenever flush valves of the RTO are all closed. The RTO further includes a hydraulic control system for minimizing variations in the operation of the RTO due to varying ambient or seasonal temperature conditions to which the RTO may be subjected. The RTO additionally includes a gravity-actuated damper valve structure near the top of a vertically arranged exhaust stack. The damper valve automatically prohibits entry of a stream of cold air into the exhaust stack, while automatically allowing heated processed air to escape the exhaust stack. The RTO is operated according to an improved six-step sequence which provides for the substantially steady-state inlet air flow, due to highly stable air draw rates. The six-step sequence maintains mass air flow rates constant, even though the inlet and outlet valves to the heat exchange chambers of the RTO are opening and closing, and produce periodic air flow reversals within the heat exchange chambers. During the six-step sequence, the steady-state flow is also maintained by opening and closing the balancing valve in a way which counteracts the effects of stopping and starting the flushing gases which are periodically circulated through the heat exchange chambers.