Research On Intelligent Optimization Control Of Ammonia Distillation Process In Soda Manufacture

Distillation of ammonia in soda manufacture invariably emerges complicated characteristics such as time-delay, time-varying and multivariable coupling, etc. In this thesis, a MPC algorithm with a two-layer optimization strategy aimed to minimize consumption of ammonia for the single ammonia distillation tower is presented. Furthermore, an intelligent coordinated optimization control strategy for the ammonia distillation process with multiple parallel towers of the large soda plant is proposed.The main research work includes:1. The present situation of soda ash production at home and abroad is briefly introduced by referring to many literatures, as well as the process equipments and process control requirements of the ammonia distillation process are analyzed. Then, the status of research and application of various control strategies for the distillation process are reviewed.2. In view of the features of the distillation process and its equipments, the key control objectives and traditional control strategies of the process are systematically expounded. Based on analysis of complex dynamics of the distillation process and the limitations of existing control strategies, the necessity of the advanced process control and optimization technology is demonstrated.3. To deal with the multivariable process control problems of the single ammonia distillation tower, firstly, the Dynamic Matrix Control (DMC) algorithm is used to ensure the key process parameters in the appropriate region, and then the two-layer optimization control strategy based on DMC algorithm is proposed to minimize the ammonia consumption. At last, simulation results indicate that the two-layer optimization control algorithm of the tower is better than the DMC algorithm, such as the stronger disturbance rejection and better robustness. In addition, when the tower has an extra degree of freedom, the two-layer algorithm can optimize the process index with meeting the process stability requirement in order to reduce the steam consumption.4. For the ammonia distillation process with multiple parallel towers of the large soda plant, the intelligent coordinated optimization control strategy with real-time expert monitoring of the tower is proposed, based on the two-layer optimization control algorithm, The strategy can automatically adjust production load of the ammonia distillation towers for meeting the total production with the monitoring results of the towers. The good performance has been acquired by the application of the intelligent coordinated optimization control strategy to the actual ammonia distillation process in a soda plant.