氯化铵回收的三效降膜蒸发系统的分析

Exergy Analysis of Three-Effect Falling-Film Evaporation System for Ammonium Chloride Recycle

利用黑箱和灰箱模型对氯化铵回收三效降膜蒸发系统进行了分析,找到了系统损的关键,即二次蒸汽的消耗引起的外部损．对各效蒸发器采用白箱模型,分析了蒸发器损的主要环节,结果表明,对于一、二、三效蒸发器,传热温差引起的损率分别为77．64％、68．59％和75．87％,降低传热温差引起的损是提高蒸发系统效率的主要途径．由于浓缩热引起的损也是不容忽视的,应提高系统的真空度,采用低温蒸发路线．

Through the exergy analysis of three-effect falling-film evaporation system for ammonium chloride recycle by black box model and grey box model, the main links losing exergy most were found. The external losing exergy mainly concentrated on the consumption of secondary steam. The main links of losing exergy was analyzed by white box model in each evaporator. The results indicate that the losing exergy rates caused by the difference in temperature heat transfer were 77.64%,68.59% and 75.87%, in the first, second and third evaporator, respectively. The method to increase efficiency of evaporation system is to reduce the losing exergy of the difference in temperature heat transfer. As the concentrated heat can also cause the losing exergy, the vacuum degree should be increased and the evaporation system should operate in low temperature condition.