China Nonferrous Metallurgy

With the implementation of the “coal to gas” project in the zinc pyrometallurgical process of a smelter in Shaoguan, problems of mismatch between high calorific value fuels and the existing combustion system occurred in the key equipment such as zinc refining column. These problems include uneven temperature distribution in the hearth, incomplete combustion of natural gas, low thermal efficiency of the system, etc. In this paper, based on heat balance calculation, thermal tests, followed by diagnostic analysis and simulation, were conducted to the zinc refining column using a variety of measuring instruments. The results show that the thermal efficiency of tower B# is 52.79%. Through the thermal diagnosis and simulating calculation, it can be seen that the temperature of the combustion chamber, the pressure of the branch pipe of the natural gas burner and the flow rate of the gas outlets are unevenly distributed, the phenomenon of blow-by exists between the off-gas and preheated air in the heat exchange chamber. In addition, the energy saving and consumption reduction of the zinc refining furnace can be achieved by optimizing the nozzle structure and arrangement of natural gas system, applying air distribution combustion method with active air supply, optimally adjusting the process parameters such as reflux ratio, evaporation ratio, the feeding temperature of tower B^# and strengthening the waste heat gradient recovery and utilization.