Research On Optimization And Control Of The Process In New Dry Cement Production

New dry cement production is a multi-variable coupling, time-varying, non-linear and large time-delay control object with complex heat and mass transfer and chemical reaction process all over. Affected by the feed particle size, chemical composition, the coating off rotary kiln and free lime as well, the process is instable and conventional control method can hardly yield ideal control effect. This thesis, proceeding from the above, studies the control and optimization of the cement production process in depth. The main content is as follows:1. Introduce the principle of new dry cement production, its present status and theory briefly. Systemically summarize researches on the process control and optimization of new dry cement production home and abroad, as well as its application status.2. Analyze industrial conditions influencing the equilibrium and stabilization of the process and control difficulties. Then discusss the coupling relationship between variables and general control method of the process parameters.Finally, the necessity of applying cement production process advanced control and optimization technology was proposed.3. To deal with nonlinearity and perturbations caused by a change of hardness of the raw material in grinding process, a multi-model predictive control strategy for nonlinear system was proposed. It can stabilize the mill circuit and avoid'empty mode'and'plugging'phenomenon. Based on the control strategy, the set point optimization of mill load was achieved. The simulation results demonstrate that the proposed control and optimization strategy can improve the stability of cement mill system and mill efficiency as it works at the optimum mill load point.4. Targeting the dynamic characteristic of cement rotary kiln production process, a control strategy of model predictive control coordinated with expert systematic control was proposed. On the basis of equilibrium and stabilization of calcining and sintering,the steady state target optimization of excess oxygen content was achieved. The simulation results demonstrate that the proposed control and optimization strategy can improve the stability of cement kiln system and decrease the coal consumption compared with only model predictive control.The last part is summary and perspective.