Research On Key Technologies Of VOCs Concentration And Treatment For Printing Machinery

With the stricter and stricter control of VOCs in all walks of life,almost all enterprises have to install VOCs processing equipment.Owing to the high cost of VOCs processing equipment,some small and medium-sized enterprises,such as printing enterprises,are unable to bear the high cost,which results in the bankruptcy of enterprises.One of the reasons for the high cost of VOCs is that the selection of VOCs treatment equipment is too large,resulting in low gas collection efficiency.In order to solve this problem,this paper studies the collection and processing of VOCs.In order to solve the problem of collecting efficiency of VOCs in printing machinery,this paper takes the existing four-color printing press in the laboratory as an example to study the movement law of two kinds of airflow: suction and blower.On this basis,a three-dimensional model of four-color printing press is established.The gas collecting hood is locally arranged in the space generated by VOCs.The volume and structure of the gas collecting hood are studied by generating the expected air flow law.The new gas collecting method can reduce the amount of exhaust gas collection by at least 80%.In order to reduce the loss of air flow in the selected gas collecting scheme,five kinds of air flow directions are proposed in this paper.Based on the production and emission process of VOCs in printing equipment,a physical model was established,and the environmental variables such as temperature and pressure were assumed appropriately.On the basis of the Gauss model,the three-dimensional model was simplified,and the concentration and diffusion model of VOCs was established.The existing ventilation schemes are simulated by FLUENT 15.0 software.The RNG k ? ?turbulence model is adopted and the Euler-Lagrange discrete term model is chosen as the multiphase flow model for fluid simulation.The simulation results of airflow velocity,benzene concentration,airflow pressure and streamline in ventilation scheme are discussed and analyzed.The simulation results of airflow velocity,benzene concentration,airflow pressure and streamline of ventilation scheme are discussed and analyzed.It is concluded that the distribution of pollutant concentration is the most concentrated when the vent opens symmetrically on the top of the gas collector,the pumping pressure is 906 Pa,and the energy consumption is 0.37 times as much as that of the side opening scheme.Among the five air flow patterns,energy consumption is the lowest and purification is the highestIn order to verify the validity of the selected scheme,taking the printing plant of our university as the test point,the weight of the existing VOCs purification process is calculated by using the analytic hierarchy process.It is concluded that the regenerative catalytic combustion method should be used to treat VOCs collected in the printing workshop.Under the condition that the air purification rate reaches the standard(according to the VOCs concentration test results,the air purification rate is 94%),the cost of the new treatment scheme is 0.79 times that of the existing scheme.