Abstract: The model of complex countercurrent multi-effect evaporation with condensed water flash and extra vapor withdrawal is established. The conventional model of countercurrent multi-effect evaporation is a simplified example of the new model.The new algorithm which combines matrix method with iteration method is presented.The new method is an effective method for solving the model of multi-effect evaporation system,and increases the convergence speed and stability compared with Boryden method.The practical example indicates that the method used in complex countercurrent multi-effect evaporation system is fast and accurate.The vapor consumption of three-effect evaporation with condensed water flash is decreased by about 10% for condensation of NaOH solution. Loss of heat energy increases for preheating of feed with fresh vapor or extra vapor withdrawal.

摘要： 建立了有冷凝水闪蒸和额外蒸汽引出的复杂逆流多效蒸发系统的数学模型 ,常规逆流多效蒸发模型只是该模型的一个特例。提出一种新算法———迭代法结合矩阵法求解模型并给出算法框图。迭代法结合矩阵法与目前较先进的Broyden法相比 ,具有对初值要求不高、收敛稳定性好、收敛速度快等优点 ,是求解多效蒸发问题的一种新的有效方法。算例表明 :模型可用于复杂逆流多效蒸发系统的快速求解 ;对三效逆流蒸发NaOH溶液系统 ,采用冷凝水闪蒸可节省加热生蒸汽 10 %左右 ,节能效果显著 ;逆流多效蒸发采用生蒸汽或引出额外蒸汽预热原料液不仅不会节能 ,反而造成热能损失