Modeling And Control Of Evaporators In Cane Sugar Industry

The evaporator station is a key process step in the cane sugar mill. Its robust control is essential to guarantee the output syrup concentration as close as possible to the desired values to feed to the crystallization process and optimize the energy used. Therefore, modeling and control of the evaporating process is of the highest importance in the sugar industry.On the basis of comprehension of the evaporating process flow and principle of multiple-effect evaporation, according to the following plant features: strong disturbances, great nonlinearity, many constrains and so on, The error BP(BackProragation)neural network is used to establish a model and describe the complex relationship among the juice steam pressure of the second stage and the syrup brix leaving the multiple-effect evaporator. The simulation result proves the validity of the model which has strong ability to describe the multiple-effect evaporation and reveal the performance of the syrup brix leaving the multiple-effect evaporator.The predictive control algorithm is introduced in another part of the dissertation, and analyze application of nonlinear MPC in cane sugar multiple-effect evaporation, then a MPC algorithm which based on BP neural network model and genetic algorithm optimization is discussed. A simulation has been taken to the multiple-effect evaporation by means of nonlinear MPC algorithms. From simulation result, it receives good effect and reaches the requirement of control.