A thermal oxidizer is a process unit for air pollution control in many chemical plants that decomposes hazardous gases at a high temperature and releases them into the atmosphere. It is generally in the shape of a cylindrical stack, and usually releases at one of the highest altitudes in the facility. While the temperature and gaseous composition during operation is lethal, a thermal oxidizer must frequently be checked inside for cracks during downtime. A steady, visible flame during operation at night is considered normal, but emission of sparks is a sign of poor combustion and may require changing the temperature or gaseous inputs. The device is generally hooked up to control systems to aid in this correction, although changes are often necessary not only within the stack, but in the process units upstream.
