Abstract: This paper addresses practical problems in industrial process control, describes the energy-saving principle of frequency converters, introduces solutions to some technical problems in the transformation of the combustion process control system of a 65T/H boiler using variable frequency speed regulation technology, and provides a reliable way for industrial enterprises to achieve energy conservation, consumption reduction and improved production efficiency. Keywords : frequency converter; fan; energy saving; control system; regulator. Two 65T/H boilers of Giti Tire Co., Ltd. were originally equipped with a combustion system using a damper-type control for the forced and induced draft air volume and a slip-ring excitation type for regulating the coal feed. The main defects were: (1) The fan motor power design had to consider fuel, heat load, electrical load, season, and margin in case of accidents, so the configuration was generally large. Long-term operational statistics showed that the damper opening was generally between 40% and 80%. This method of manually increasing resistance to regulate air volume wasted a lot of energy. Furthermore, the poor damper regulation accuracy made automatic control difficult. (2) The damper regulation equipment had a high failure rate and high noise levels, and the motor's full-voltage start-up had a significant impact on the power grid. (3) The system was not suitable for fully automatic control, and its stability and reliability were poor. Therefore, we adopted modern frequency conversion technology to upgrade the system, improving equipment operation quality and achieving energy saving and consumption reduction. 1. Variable Frequency Speed ​​Regulation Energy-Saving Principle and Combustion Process Control System [b][align=center]For details, please click: Application of Variable Frequency Drives in Boiler Combustion Systems[/align][/b]