Abstract : The existing boiler system is retrofitted using a frequency converter to improve product quality and save labor, time, and energy, thereby significantly increasing labor productivity. Keywords : Boiler; Frequency converter; Energy saving 1 Introduction Currently, AC frequency converter speed control technology, with its superior speed control performance and energy-saving advantages, has been widely applied in various industries, achieving considerable economic benefits. When applied to boiler systems, this technology significantly improves energy efficiency compared to other methods, and can further enhance the stability, safety, and control accuracy of system operation. [b]2 Boiler System Retrofit 2.1 Retrofit of the Induced Draft Fan[/b] The original induced draft fan operated by direct start-up and industrial frequency operation, with its air volume adjusted by regulating the damper opening. The disadvantages of this method are high energy waste, poor real-time adjustment, high noise, and high labor intensity for workers. The proposed modification scheme is to use a pressure closed-loop circuit composed of a differential pressure transmitter, frequency converter, controller, and induced draft fan to automatically control the speed of the induced draft fan, maintaining a stable slight negative pressure in the furnace. This improves control accuracy, saves energy, and makes the induced draft fan control economically sound. 2.2 Blower Modification The original blower operated under reduced pressure and industrial frequency conditions, with its airflow adjusted by the damper opening. This control method has disadvantages such as high energy and fuel waste, poor real-time adjustment, high noise levels, and high labor intensity for workers. Therefore, a frequency converter modification scheme is proposed: using a differential pressure transmitter, frequency converter, and blower to form a pressure closed-loop circuit to automatically control the blower speed, maintaining a stable steam pressure at the boiler outlet. This improves control accuracy, saves energy (electricity and fuel), and makes the blower control economically sound. [b][align=center]For more details, please click: Application of Variable Frequency Speed ​​Control Technology in Boiler Modification[/align][/b]