Integrated Design And Application Of The Automatic Control System For Wastewater Treatment Plant

After the large-scale construction stage of sewage treatment plantsduring "11th Five-Year Plan",in "12th Five Year Plan",China will enter the stage of small town sewage treatment facilities construction,sewage treatment plants upgrade,sludge treatment and disposal,the use of recycled water and supporting pipe network,diversion of rain and sewage water pipe network transformation,the main point will turn to the upgrading of small town sewage treatment facilities and sewage treatment plant.In the process of upgrading,the data of the new equipmentis often collected and transmitted by the new automatic control system.The new and the existing automatic control system need to be integrated to achieve data sharing,centralized management,decentralized control,and thus improve the efficiency of operational management,save energy and liberate the productive forces.Aiming at these problems,this study proposes a design scheme of upgrading and integrating the automatic control system of sewage treatment plants.Based on OPC technology,it use a new configuration software for the whole system.The new system use the same PLC module brand as the existing system,the main equipmentsuch as lifting pumps,blowers,sand-waterseparation facilitiesare optimized and integrated by PLC.The new system PLC master station and the original PLC stations form a ring Ethernet communication network.Look at the sewage treatment plant in Zhongshan Huangpu town as an example,the project used OPC to unify data format and transmission system,made the design of function and configuration in the new system at all levels,network structure and function,the reliability of the system,the key equipment and online instruments selection,meanwhile,planed with big data for the system.By controlling the main points of the project(such as setting OPC server and client,importing and exporting all variable,reading digital variable,uploading and downloading PLC and HMI program,system debugging and inspection),the new system and the original system linked perfectly through the integration of design,the installation of the quality control and the optimization of lift pump rotation.According to the rated flow classification,level control and priority control combined lift pump automatic rotation mode for the inadequate inlet sewage treatment plant,this study provided a new rotation scheme for the different rated flow and collocation of soft start and frequency conversion of lift pump combination.Through the planning of big data it find out the improvement potential site and the development direction of system optimization in the future.After integrating,the power consumption per unit of water was decreased by 21%,the pump energy consumption was lower than before by 24%,the dissolved oxygen in the new system reached the set range of allowed values in 71% of the time,and the stability reached 87%.The investment of this project is about 101 million yuan,only accounted forthe equipment procurement and installation cost about 4% for the sewage treatment plant upgrade,taking into account the Huangpu wastewater treatment plant of the latter upgrades and the project main equipment areall well-known international brands,the cost of integrate is economical.The integrated design scheme is cost-effective,advanced,reliable,economical and practical.