管道化溶出系统预热级数的模拟优化

Simulation and Optimization of Preheating Stage for Tube Digestion System

通过对拜耳法氧化铝生产的管道化溶出过程热平衡的模拟计算,分析了不同预热级数对新蒸汽用量、换热面积及总设备费用的影响。建立了以年总费用(包括年设备折旧费、维修费、蒸汽费用及电费等)最小为优化目标、预热与闪蒸级数(n)为决策变量的优化计算模型。某典型条件下的计算结果表明,n从5增加至16,新蒸汽用量减少了20.4%,总换热面积增加近29.0%,年总费用先减小后增大,过程最经济级数为11。敏感性分析显示,新蒸汽的单价对优化结果影响显著,其变化±50%会引起年总费用变化±22%以上,同时最经济级数由8变至14。

The effect of preheating stage on live steam consumption,heat transfer area and equipment costs was studied by computation of heat balance of Bayer tube digestion system.The optimum mathematical model of tube-heating retention-tank digestion was established,which aimed at the minimization of the total annual cost（TAC,including the costs of live steam,power,equipment depreciation and maintenance） and based on the preheating stage（n） as decision variable.The practical example indicated that when n increased from 5 to 16,the live steam consumptions decreased by 20.4%,however,the total heat transfer areas increased by about 29.0%,while n=12,the TAC is minimum,which might be considered as the economical preheating stage（nopt） under the given conditions.Through sensitivity analysis,it was found that the live steam price significantly affected the result,which changed ±50% would cause the changes in TAC over ±50% and made nopt shift from 8 to 14.