Abstract : Currently, variable frequency speed control technology has become a major development direction in modern electric drive technology. Its superior speed control performance, significant energy-saving effect, improved operating conditions of existing equipment, enhanced system safety and reliability, increased equipment utilization, and extended equipment lifespan are all advantages that are becoming increasingly apparent with the expanding application areas. This article introduces the practice of variable frequency drive retrofitting of the sulfuric acid system fans at Shanxi Northern Copper Industry, providing a reference for similar retrofitting projects in the industry. Keywords : Fan; Coupling; Variable Frequency Drive; Speed ​​Regulation; Economic Benefits The sulfuric acid system of the Yuanqu Smelter of Shanxi Northern Copper Industry utilizes mixed flue gas from a closed blast furnace and converter copper smelting to produce sulfuric acid. Due to significant fluctuations in the mixed flue gas volume and SO₂ concentration, the Shenyang Blower Factory's S1200-16 centrifugal blower was selected. Initially, this blower used a hydraulic coupling speed regulation system. Although hydraulic couplings offer advantages such as flexibility, stepless speed regulation, and the ability to start the motor under no-load conditions, saving starting energy consumption, the blower's average monthly power consumption has remained around 600,000 kWh in recent years, accounting for 2/3 of the total power consumption of the sulfuric acid system, significantly impacting sulfuric acid production costs. Through specific analysis and demonstration, it is believed that modifying the existing system by replacing the coupling speed regulation with direct frequency conversion speed regulation of the motor can not only achieve stepless speed regulation of the blower but also more effectively reduce power consumption by adjusting the motor shaft output power, thus achieving energy saving and consumption reduction. 1. System configuration after modification (1) SO2 blower model: S1200-16; Flow rate: 1200m³/min; Inlet pressure: 0.085MPa; Outlet pressure: 0.13MPa; Prime mover power: 1250kw; Main shaft speed: 5725r/min. (2) Speed ​​increaser model: GYD-300-1250/1.9796; Maximum power: 1250kw. (3) Motor model: Y500-2; [b][align=center]For details, please click: Practice of frequency conversion modification of sulfuric acid blower[/align][/b]