氧化锌法式圆炉燃烧系统及结构优化

Optimization of Combustion System and Structure for the French Process Zinc Oxide Furnace

氧化锌的生产可分为火法和湿法两种工艺,法式氧化锌生产工艺是火法间接氧化锌生产的一种重要工艺。本文以浙江某厂的一台氧化锌法式圆炉为研究对象,采用数值模拟方法对该窑炉的加热工艺及结构进行优化,并通过改造实施进行验证,有效提高了氧化锌法式圆炉的热效率,增加了窑炉的使用寿命。通过对法式圆炉燃烧井及燃烧空间的数值模拟,对比分析了燃烧器型式及燃烧井结构的变化对窑炉温度场、流场及气体浓度场等的影响,据此提出了合理的优化改造意见,模拟结果与实测数据吻合良好。依据模拟结果对法式圆炉进行节能技术改造,首先将燃烧器型式由大气式改为预混式,并采用空燃比例调节装置,控制天然气和助燃空气的比例及混合程度;其次将炉窑燃烧井由竖直结构改为扩口结构。技术改造之后,生产每吨氧化锌的天然气单耗由240Nm3降至192Nm3,日节约天然气360Nm3;内外坩锅寿命由3个月提高至6个月;每个生产周期氧化锌平均产量由7.5t/d提升至8.0t/d,单台窑炉的年经济效益可达50万元人民币。

The process of zinc oxide production could be divided into two processes including fire and wet.French process is an important method for indirect ZnO production.A French ZnO furnace in Zhejiang Province is taken as the research object,the heating process and structure of the furnace are optimized and confirmed by means of numerical simulation and are tested through implementation,which effectively enhances thermal efficiency and extends the life-span of the furnace.By using numerical simulation of fire tunnel and combustion chamber,the effects of both burner type and furnace structure on the temperature field,flow field,and concentration field in the furnace are simulated and analyzed.Several reasonable optimization methods and reformation advices are put forward,and the simulation results are consistent with the field test results quite well.The furnace is reformed according to the simulation results,gas burner is changed from atmospheric to premixed,and the device for the air-fuel ratio adjustment is used to control the ratio of air and fuel,then the fire tunnel is changed from vertical structure to flaring structure.After these technique transformations as mentioned above,the gas consumption for one ton ZnO decreases from 240Nm3 to 192Nm3,and for each single day,360Nm3 natural gas is saved,the average production of ZnO increases from 7.5t/d to 8.0t/d,and the life-span of the inner and outer crucibles of the furnace increases from three months to six months.The economy benefit due to the energy saving reconstruction is up to fifty thousand Yuan RMB per furnace per year.