多效蒸发海水淡化系统的动态模拟

Dynamic simulation of MED seawater desalination system

多效蒸发海水淡化系统动态模拟的研究目的是建立一个完整的多效蒸发海水淡化系统动态模型,分析当系统输入参数变化时系统内其他参数的动态响应规律,并能根据动态模拟结果制定合理的控制方案。研究方法主要采用的是Aspen软件模拟。蒸发器是多效蒸发海水淡化系统的主要单元,在Aspen Plus软件中选用Heater、Flash、Pump和Split模块完成单效蒸发器模型的建立,在单效蒸发器模型的基础上建立了带有热量回收段的多效蒸发海水淡化流程。以六效蒸发海水淡化系统为例,采用与海水等盐度的NaCl溶液作为模拟介质进行模拟。稳态模拟的结果作为Aspen Dynamics软件进行动态模拟的初始参数。动态模拟过程中,分析了最高盐水温度、进料海水温度和进料流量波动时,多效蒸发系统中各参数的动态响应规律,以此为基础根据过程控制工程中制定控制方案的要求提出3种不同的控制方案。在Aspen Dynamics软件中对3种控制方案的控制效果进行比较,选择了恢复时间短,抵抗外界干扰的能力强的控制方案。动态模拟的研究结果对实际生产中的多效蒸发海水淡化系统的控制具有一定的指导意义。

The purpose of dynamic simulation of MED seawater desalination system is to build a complete dynamic model for the MED seawater desalination system and analyze the law of system parameter＇s dynamic response when System input parameters change.According to the result of the dynamic simulation,a reasonable control scheme was put forward.Using Aspen program is the main research method.The evaporator is the most important unit of Multi-Effect Distillation（MED） desalination system.In Aspen Plus software,the modules of Heater,Flash,Pump and Split are selected to model the evaporator and the MED flowsheet,based on which Multi-Effect Distillation desalination system was built with heat reclaim unit.Taking Six-Effect Distillation for example and adopting the NaCl solution with the seawater salinity as the simulation of medium to carry out the simulation work.The result of steady simulation is the input parameters of the dynamic simulation.The dynamic behavior of MED is analyzed with Aspen Dynamics when the top brine temperature,seawater temperature or seawater mass flow changes.According to the result of the dynamic simulation,three different control strategies were put forward due to the rules in process control engineering course.After testing the control effect,a control scheme with shot recovery time and strong ability to resist interference was adopted.The research of the dynamic simulation of MED seawater desalination system is significant to the control of MED seawater desalination system.