硫酸铵溶液三效并流蒸发系统的动态模拟

Dynamic simulation of three effect concurrent evaporation system of ammonium sulfate solution

以江苏某化工厂三效并流蒸发含有一定浓度氨气的硫酸铵溶液为例,采用Aspen Plus软件进行稳态模拟,以稳态模拟结果作为动态模拟的初始条件,建立三效并流蒸发系统的动态模型,利用Aspen Dynamics软件对带有基本控制结构的三效蒸发溶液浓缩系统进行研究,分析进料流量、温度和组成发生变化时系统其他参数的变化规律。结果表明,当进料流量、温度及组成发生变化时,液相出口浓度阶跃性变化。为使液相出口浓度保持恒定,制定了2种控制方案,进料流量串级控制和加热蒸汽流量串级控制,并对其控制效果进行比较。动态分析表明,2种控制方案均能稳定液相出口浓度,但加热蒸汽流量串级控制方案超调量更小、恢复时间更短。动态模拟结果对实际生产操作的多效蒸发溶液浓缩系统的控制提供一定的指导作用。

Taking three effect evaporation system of ammonium sulfate solution（ containing a concentration of ammonia） of a chemical factory in Jiangsu as an example,the steady state simulation is performed by using Aspen Plus software. With the steady state simulation results as initial conditions of dynamic simulation,a dynamic model of three effect concurrent evaporation system is established. Three effect evaporation-condensation system with basic control structures is studied with Aspen Dynamics software. When the feed flow,temperature and composition are changed,the change of other parameters in the system is also analyzed. The results show that the outlet concentration of liquid phase has a step change with tha change of the feed flow rate,temperature or composition. In order to make the outlet concentration of liquid remains constant,two kinds of control schemes,feed flow cascade control and heating steam cascade control,are put forward. Their control effects are compared. Dynamic simulations show that two kinds of control scheme both can achieve the stable liquid concentration of export,but the control scheme with heating steam flow cascade control has a smaller overshoot volume and a shorter recovery time. Dynamic simulation results provide some guidance for the control of the multi-effect evaporation system for the practical production operations.