In order to prevent the high concentration of VOC exhaust gas entering the RTO (RCO) furnace from causing explosion hazards, and to prevent the environmental problems of excessive emissions caused by insufficient combustion due to high concentration of VOC exhaust gas entering the RTO furnace, it is necessary to monitor and control the inlet VOC exhaust gas concentration of the RTO furnace within a certain reliable range to ensure the reliable and safe operation of the entire RTO furnace.