Multi-objective Real Time Optimization Of Desulfurization System Based On Predictive Control

The wet limestone desulfurization system is widely used in power plants,however,traditional desulfurization system operation strategies usually focus on the increasingly stringent environmental emission targets while ignoring the economic factors such as desulfurizer consumption,system operational power consumption.In view of the aforementioned problems,it is urgent to study a multi-objective real-time optimization strategy which is suitable for the desulfurization system for improving safety performance,environmental performance,and economic performance.In the paper,the mathematical model aiming at multi-objective optimization control was constructed,and the multi-objective optimization was proposed so that the optimization performance was analyzed.The WFGD mathematical model is established.By focusing on the processes of SO₂absorption,slurry circulation update and flow control,the impact between key factors such as fresh slurry flow,circular slurry flow,slurry properties,and pump unit switching methods and emission characteristics was obtained.The circular slurry flow has a great influence on the desulfurization performance,while the fresh slurry flow significantly affects the slurry properties.Based on modular modeling,each module fully considered factors which closely related to environmental performance,economic performance,and safety performance.It provided parameter basis for the multi-objective optimization control subsequently.Based on the dynamic characteristics above,the influences between various factors and optimization goal were evaluated,and multi-objective optimization suggestions were proposed.The economic index,safety index,operational smoothness index,and environmental index were quantified,and the influences between operating parameters such as state variables and control variables and performance indicators were analyzed.The objective functions and constraints of multi-objective optimization problems were constructed,and the multi-objective optimization suggestions were obtained.Compared with single-objective optimization,the slurry supply under high flue gas volume maintained a low value,which significantly reduced the limestone material consumption.The influences between the circular pumps,slurry supply pumps and the cost was analyzed.Under high flue gas volume,the control mainly based on the slurry supply pump can effectively improve the operation economic performance.Based on the aforementioned optimization suggestions,predictive control method was introduced to achieve WFGD multi-objective real-time optimization.The mathematical model was used as a prediction model,and various performance indicators were introduced into the control framework.Through state prediction,objective function solution,rolling optimization and other steps,economic model predictive control was realized which closely fitted the system process characteristics and multi-objective optimization requirements.Compared with the conventional operation methods,it can not only effectively overcome the control difficulties caused by dynamics characteristics such as non-linearity,large lag,and multi-variables,but also optimize multiple performance indicators simultaneously.The WFGD optimization decision-making software was developed to realize engineering application.The joint programming method containing App Designer and Simulink was adopted,and the human-computer interaction interface was designed.The previous research results were integrated into three functional modules,prediction functional module,optimization functional module and control functional module,the optimal adjustment of slurry flow and pump group switching was realized.Compared with the existing software,this application was highly automatic,and effectively handled different types of operating indicators such as material consumption,power consumption,emission indicators,and operating safety.