Abstract:This paper introduces the off-gas-based acid making process, the sulfur dioxide compressor and its VSD device of a smelter. It provides a list of resistance calculation formula for the main equipment, pipelines, tower packing, demister and conversion catalyst bed, and gives a statistics of actually measured data on the system resistance of the sulfuric acid plant under different loads of the sulfur dioxide compressor, analyzes the resistance variations of the main systems of the sulfuric acid plant under different loads of the compressor, and puts forward its suggestion that the sulfuric acid plant may use sulfur dioxide compressor complete with VSD when conditions permit.