Abstract:Based on the on-line monitoring system of ultra-low emission flue gas for two million units of Shenfuhong Electric Power Station, this paper analyses the structure and measurement principle of CEMS system, and introduces the principle of high and low range switching of the instrument itself and its implementation. Simulated tests were carried out during unit standby, start-up and operation. The high and low range switching signals triggered normally, the high and low range switching of the instrument itself was normal, and the environmental protection parameters of the unit were monitored normally under different working conditions.