Research On Optimization And Application Of VOCs Exhaust Gas Collection System In Printing Workshop

The total emission control of VOCs is mainly determined by its collection efficiency and purification efficiency.The study found that the import concentration of VOCs exhaust gas purification facilities in some polluting enterprises was lower than the standard.It is mainly due to the fact that the collection efficiency of the VOCs exhaust gas collection system in actual work is difficult to meet the design requirements.And the VOCs have large unorganized emissions.Due to the difference in packaging printing work time or printing scale,it is of great significance for the printing shop to effectively improve the collection efficiency of VOCs under different working scenarios.The research focused on the VOCs exhaust gas collection system in the lithography workshop and determined the amount of exhaust gas.The numerical simulation method is used to optimize the design of the system,improve the exhaust gas collection efficiency of VOCs,and achieve the goal of controlling the unorganized emission of VOCs,and provide technical support for VOCs emission reduction control.The study yielded the following results:(1)As the wind speed of the hood increases,the entrainment effect of the hood continues to increase,and the VOCs concentration area of the cross-sectional space continues to decrease.The distribution of the concentration field distribution simulation results is basically consistent,that is,the concentration of pollutants in the section is more concentrated in the vicinity of the center of the gas collecting hood,and it tends to gather toward the center.(2)The pressure imbalance can be effectively adjusted by adding a regulating valve to the system branch pipe.The maximum deviation of the air volume of the collecting system after the adjustment is reduced from the initial 41.81% to 0.261%,and the maximum resistance imbalance of the branch is from the initial 23.77%decreased to 0.43%.The addition of a triangular plate at the gas collecting hood opening can effectively adjust the air volume of the gas collecting hood,and each gas collecting hood basically reaches the design air volume,and the whole system can basically reach the state of full negative pressure balance.(3)The numerical simulation results show that the resistance of each working mode collection system has reached equilibrium,the air volume has reached the design air volume requirement,the maximum deviation of the working branch air volume is0.261%,and the respective gas collecting hoods basically reach the design air volume.The whole system can basically reach the full equilibrium negative pressure state.(4)The numerical simulation method can provide reference for the transformation of VOCs exhaust gas collection system and provide technical support for VOCs emission reduction control.Propose the control method of the fully balanced negative pressure exhaust gas collection system in different working scenarios,it is entered the valve opening degree and the motor frequency in the program when each branch reaches the design air volume in each working mode by using the PLC control system.Thereby,the switching and resistance balance of each working mode of the system can be realized.And the automatic intelligent control of the VOCs exhaust gas collection system is realized.