Study On The Optimization Control Strategy Of Aerobic Treatment Process For Papermaking Wastewater Based On DE Algorithm

With the development of socialism with Chinese characteristics into the new era and the guidance of the policy of "building a beautiful China",the pressure of environmental protection for pulp and paper company has been greatly strengthened.Wastewater treatment has become a crucial factor for the sustainable development of enterprises.Aerobic treatment,as a common biological treatment,is widely used in most pulp and paper company because of its advantages of less consumption,high efficiency and low cost.The aeration process,as the key link of aerobic biological treatment,is to maintain the concentration of dissolved oxygen in the aeration tank to a certain extent.However,the aeration process is nonlinear,time-varying and difficult to establish a model accurately,the traditional control strategy has some problems such as low accuracy of dissolved oxygen control,large parameter setting and large energy consumption.So,under the support of the innovation team of energy saving and environmental protection key equipment and control engineering of light chemical industry(2014KCT-15),the optimization control strategy is studied around aerobic treatment aeration process.In this paper,the optimization control technology and intelligent control technology of aeration process in aerobic process are put forward.On the premise of guaranteeing the water quality,the energy consumption is reduced and the control precision of the system is improved.The main works of this paper can be summarized as following four aspects:(1)The establishment of a state model for aerobic treatment of process papermaking wastewater.Combined with the characteristics of papermaking wastewater and practical technology,this paper established the aeration and activated sludge discharge,return sludge as control variables,organic matter concentration,biomass concentration,dissolved oxygen concentration as the basic state of the activated sludge aeration process of state variable equation based on the analysis of the traditional mathematical model of aeration process.It has realized the simplification of the traditional model and laid the foundation for the research of energy saving optimization control strategy in aeration process.(2)Optimization of aerobic process parameters based on DE algorithm.In addition to the control loop of aeration,the quality of the effluent is closely related to the control loop of the discharge of excess sludge and the amount of reflux sludge.In this paper,the main control loop of aerobic treatment process is taken as a whole,and the model of optimal control system for aerobic treatment is established.Through the basic state equation of aeration process,a mathematical model suitable for optimal control is derived.On this basis,the performance indexes including the operation cost of the blower,the cost of the surplus sludge discharge and the discharge of the reflux sludge are set up.Taking the effluent quality as the constraint condition,the basic differential evolution and its improved algorithm are used to optimize the aerobic biochemical reaction process,and the optimal control curve of the main control parameters of the aerobic process is obtained.On the basis of guaranteeing the water quality to meet the standard,the running cost is reduced and the energy consumption is reduced.(3)Concentration control of dissolved oxygen in aeration process.The characteristics of dissolved oxygen concentration control system are studied,and the common strategies of dissolved oxygen concentration control are introduced.Based on that,a fuzzy PID controller is designed for dissolved oxygen concentration control loop.The simulation experiments of the fuzzy PID controller and the conventional PID controller are carried out on the Simulink simulation software platform.The simulation results show that the fuzzy PID controller is superior to the conventional PID control in terms of control accuracy,response speed,tracking performance and robustness.Therefore,the effect of dissolved oxygen concentration control system is expected to be improved.(4)Design of process control system for aerobic treatment of papermaking wastewater.On the basis of the analysis of the key points of aerobic treatment process,the design of the control scheme is completed and the DCS control system of aerobic treatment process is developed.It includes hardware configuration,detection instrument selection,control algorithm realization and WinCC picture drawing of upper computer.In this paper,a state model of aeration process for aerobic treatment of papermaking wastewater is established.Under the premise of ensuring the effluent quality,the differential evolution algorithm is applied to optimize the main control loop parameter setting value of oxygen treatment process,so as to reduce the energy consumption;Secondly,the fuzzy PID control strategy is introduced into the dissolved oxygen concentration control loop,which improves the control accuracy of aeration process;finally,by completing the design of DCS control system of aerobic process,the optimal control strategy is designed and implemented on the upper computer platform.The results of the study show that the design with aerobic treatment process DCS control system optimization control strategy can effectively reduce the energy consumption of papermaking wastewater aerobic treatment,improve the product quality and the production process automation level,reduce operating costs,enhance the competitiveness of enterprises,meet the basic requirements of the national construction of " building a beautiful China ".