铅锌联合冶炼300 kt/a制酸转化工序换热器技改实践

Technical renovation practice of heat exchanger in the 300 kt/a acid conversion process of lead zinc joint smelting

介绍了铅锌联合冶炼项目配套的300 kt/a制酸装置的Ⅱa换热器在运行中存在的问题及改造情况。从铅锌联合冶炼烟气的特点、气体偏流影响、换热器材质、烟气中含有氮氧化物、烟气的水分和氟含量高等方面分析了换热器产生腐蚀及堵塞的原因,通过新增L型牺牲式换热器和电加热器对转化工序进行改造。生产实践证明,电加热器的应用效果一般,使用次数较少;采用L型牺牲式换热器使Ⅱa换热器烟气平均温度升高,远高于露点,减少了冷凝酸的形成和管程堵塞现象,管程阻力降由2.04~13.35 kPa下降至1.70~5.71 kPa。对Ⅱa换热器进行改造延长了设备使用周期,在节省维修成本的同时实现了制酸系统长周期稳定运行。

The problems and renovation situation of theⅡa heat exchanger in the 300 kt/a acid production plant supporting the lead zinc joint smelting project during operation are introduced.The causes of corrosion and blockage in the heat exchanger are analyzed from the characteristics of the flue gas from lead zinc joint smelting,the influence of gas bias,the material of the heat exchanger,the presence of nitrogen oxides in the flue gas,and the high moisture and fluorine content in the flue gas.The transformation process is modified by adding an L-shaped sacrificial heat exchanger and an electric heater.The production practice shows that the application effect of electric heaters is average and it is used less frequently;the use of an L-shaped sacrificial heat exchanger increases the average flue gas temperature of theⅡa heat exchanger,much higher than the dew point,reduces the formation of condensation acid and tube side blockage,and reduces the tube side resistance from 2.04-13.35 kPa to 1.70-5.71 kPa.The modification ofⅡa heat exchanger extends the equipment’s service life,saving maintenance costs and achieving long-term and stable operation of the acid production system.