| Continuous process control is a key technology in industrial production.It is mostly used in large-scale production of chemicals,fuels and polymers,such as DCS production process of polyvinyl alcohol and crude benzene regional control system of chemical plant,etc.,which determines the quality,type and production capacity of industrial production.So it has certain research value.Most continuous processes have complex control,too many regulating parameters and disturbance factors.They are characterized by high temperature,high pressure,multi-input,multi-output,strong coupling and strong non-linearity,etc.Therefore their operation conditions are changeable and difficult to control.For the traditional continuous process system,the material waste and low output caused by recycling process of the material are neglected.Considering safety,production optimization,energy saving and environmental protection comprehensively,this thesis adopts the improved cascade-ratio control strategy to achieve material recycling,and uses the single neuron adaptive PSD algorithm to control the pressure of the flash tank to achieve the purpose of rapid adjustment and increase the system output.Based on PCS7 and SMPT-1000,the continuous process control strategy is realized and verified.Based on the detailed description of the process and control requirements,this thesis uses the SDG diagram method to analyze the coupling relationship of various parameters and develops an improved cascade-ratio control strategy with recycling process,and the control ideas of the eight parts of the whole system.The positive and negative effects and control rules of PID controller are summarized.The general table and block diagram of controller design for process control system are also given.Based on PCS7,the CFC configuration of the control scheme is carried out,and parallel SFC is adopted to accelerate the control process.The parameter configuration and implementation process of the recycling process are described in detail.Traditional PID control can’t self-learn tuning parameters,but single neuron and PSD algorithm can adapt and self-adjust parameters.In view of the uncertainty and time delay of the flash tank pressure,a single neuron adaptive PSD algorithm is adopted for control.Based on the SCL language programming and generating functional blocks,the single neuron adaptive PSD-PID compound cascade control is configured in the CFC,while other circuits remain unchanged.Combined with the process control process,based on WinCC designed the main interface,alarm,flow accumulation and other configuration,andadded the safety display panel and emergency stop function.The real-time monitoring of the entire continuous process control system is realized.Important indicators such as concentration,final yield,and recycling process flow can be directly visualized.Experiments on the SMPT-1000 platform show that the single-neuron adaptive PSD is faster than the cascade PID,and the material recycling rate and product yield are improved while ensuring safety.This proves that the continuous process control strategy with recycling process has certain theory and application value.Figure [64] table [7] reference [66]. |
