Study On Control Technologies Of Integrated System For Desulfurization And Particles Removal In Low Speed Marine Diesel Engine

With the rapid development of global trade,the number of ocean-going ships has increased rapidly,and NOx,SO_X,and particulate matter in the exhaust gas emitted by marine diesel engines have caused increasingly serious harm to the global environment.In order to prevent SO_X pollution,the international maritime organization stipulates that from January 1,2020,the sulfur content of fuel oil used by international sailing ships in the global seas outside the sulfur emission control areas shall not exceed 0.5%（mass fraction）.For the particulate matter in the exhaust gas from ships,the IMO is in the research legislative stage（black carbon）.At present,there is no clear limit requirement worldwide.However,considering the seriousness of particulate pollution hazards,some countries have begun to limit the release of particulate matter from ship exhaust.The Chinese government has set strict standards for particulate emissions from ship exhaust gas in GB 15097-2016（second stage）.At present,the wet desulfurization and particle removal technology is relatively mature.In order to meet the increasingly strict emission requirements and take into account the particularity of the ship environment,the wet desulfurization and particle removal technology has broad application prospects.In this paper,low speed marine engine-exhaust gas post-treatment composite device is studied.Firstly,the integrated treatment technology of desulfurization and particulate removal of ship exhaust gas is discussed.The principle and technical characteristics of sodium-alkali wet flue gas desulfurization technology and venturi washing and removal of particulate matter technology are deeply studied,and the venturi scrubber,liquid supply system,SO_X absorption system and wastewater treatment system of integrated treatment system for desulfurization and removal of particulate matter are studied in detail according to their functions.Secondly,according to the technical characteristics and specific equipment requirements of desulfurization and particle removal system,the overall framework of desulfurization and particle removal control system is constructed,the communication platform is built,and the software and hardware system design and selection of the automatic control system of desulfurization and particle removal is completed.According to the above design,complete the main cabinet size of the control system,the distribution of the control cabinet and the design and selection of important instruments.Thirdly,the characteristics of the automatic system of desulfurization and particle removal and the main controlled parameters and adjustment methods are analyzed in detail.According to the characteristics and specific control requirements of each subsystem of desulfurization and particulate removal,a set of appropriate control strategy is designed,and the control strategy of venturi scrubber control,scrubber system control,lye supply system control,circulating pump system control and seawater cooling system control is discussed in detail.At the same time,this paper also completed the design and development of the system monitoring human-machine interaction interface.Finally,in view of the nonlinear,time-varying,and large hysteresis characteristics of the p H value control of the existing desulfurization and particulate removal system,the p H value model of the identified desulfurization and particulate removal system was simulated by using Smith prediction control technology,and compared with the cascade PID control strategy adopted by the system.The analysis results show that the overshoot,robustness and anti-interference performance of Smith estimation control are better than cascade PID control technology.The follow-up test will be completed to communicate with the PLC system and verify the Smith predictive control algorithm.The research results of this paper can provide reference for the research on the control technology of ship exhaust gas desulfurization and particle removal integrated system.