Study On Simulation Optimization And Application Of Ventilation System In A Coating Workshop

The raw materials used in paint production are mostly harmful to human health.The toxic gases were emitted from the volatile solvents during the production process and spread in the operating environment,which cause serious occupational hazards.The paint production workshop of an enterprise in Foshan was taken as the research object.The toxic gas concentration and occupational hazards in the production workshop were tested and evaluated.The ventilation status of the workshop was then simulated and analyzed.Subsequently,the engineering modification was put forward to solve the problem of high toxic concentration in the workshop.The contents of the study are as follows:(1)The coating production workshop of an enterprise in Foshan was investigated.The types of the toxic gases emitted in the coating production process were then detected.The concentration of xylene in the dispersed vehicle was found to exceed the occupational limit value.The risk of various organic poisons in paint workshops was evaluated by using the EPA risk assessment model which commonly used at home and abroad.The results showed that the non-carcinogenic risk degree of xylene in decentralized workshop was 5.76 and the non-carcinogenic risk degree of xylene in grinding shop was 2.35,which showed that the non-carcinogenic risk of xylene was high.In order to solve the problem of high concentration of xylene,the ventilation condition of dispersing and grinding workshop was improved and analyzed.(2)Three ventilation improvement schemes were proposed for the problem of high concentration of xylene in grinding vehicles: the gas sent and returned on the same side,the gas sent and returned on different side,and the gas sent and returned on both sides.Ventilation effects of different ventilation schemes were analyzed by means of simulation analysis using FLUENT software.The results showed that the ventilation efficiency of both sides sending and returning was higher,reaching 52.63%,which had a good effect on reducing and controlling the toxic gas concentration.After the modification of the grinding workshop of the enterprise,the time-weighted average concentration of xylene in the vehicle was tested.The highest concentration of xylene was not exceeding 16.32 mg / m3,the concentration of xylene in the workshop was reduced by 66.57% compared with that before the modification.The non-carcinogenic risk degree of xylene was obtained by occupational hazard risk assessment,which was 0.79,indicating risk acceptable.(3)In order to solve the problem of poor ventilation in the decentralized workshops,local ventilation improvement measures were proposed.According to the disperser structure and operation requirements,the installation position and size of the exhaust air were set.The effects of different tilt angles of the air exhaust hood and different diameters of the connecting pipes of the exhaust hood on the control effect of xylene were simulated and analyzed using the FLUENT software.Simulation result indicated that the xylene concentration in the periphery of the disperser was capable of being reduced more effectively when the tilt angle of the hood cover was 45°.Besides,the reasonable increase in the diameter of the connecting pipe of the ventilation hood could effectively improve the control effect of the toxic gas concentration.After the partial ventilation modification of the company’s decentralized workshops,the time-weighted average concentration of xylene in the operators’ activity area was not exceeding 12.35 mg/m3,reduced by 89.56% compared with that before the conversion.The risk assessment for xylene had a non-carcinogenic risk of 0.6 and it was acceptable.The research content of this project is closely integrated with the actual production.The airflow and the concentration distribution of toxic gases in the workshop were analyzed by means of numerical simulation methods.The local ventilation system was then optimized for the production equipment.The present study provides a support and reference for the ventilation design of similar workshops.