Selection And Optimization Of VOCs Pollution Ventilation Method In Cfd Lithographic Printing Workshop

In order to improve the efficiency of ventilation,printing workshop in VOCs exhaust fumes,effectively reduce VOCs unorganized emissions and control a reasonable workshop labor health situation,through field tests and numerical simulation method for analysis of the existing ventilation mode in offset printing workshop,and USES the method of numerical simulation on the lateral air supply,air supply,compares two different ways of air supply and below the isentropic surface concentration is given to meet the requirements of specification ventilation way.At the same time,combined with the field operating conditions,by changing the air supply height,air supply speed and air supply volume of the way to optimize the structure of the upper air supply,so that the ventilation system in a reasonable new air volume to achieve the ideal ventilation effect,so that the workers to meet the health conditions.The study reached the following conclusions:(1)Under the condition of lateral air supply,even if the air volume is doubled,the concentration on the isentropic surface and below still does not meet the specification requirements,and VOCs gas will accumulate near the ground;Under the condition of upper air supply,the concentration below the isentropic surface is still far lower than the standard requirements when the air volume is set to a small value,which can effectively improve the labor health conditions of workers.(2)The concentration distribution of VOCs produced in lithographic printing workshop was analyzed through field test.The concentration test results showed that the non-methane total hydrocarbon concentration showed a gradual decreasing trend from bottom to top in space,which was the same as the concentration distribution trend of toluene in numerical simulation.(3)Optimize the upper air supply mode by air supply volume,air supply speed and exhaust outlet position.When the air supply volume increases,the concentration of pollutants below the isentropic surface in the lithographic printing workshop decreases;When the air supply speed increases,the VOC concentration distribution in the workshop decreases with the increase of the air supply speed.When an outlet is added in the location where pollutants are easy to accumulate,the accumulation of pollutants in the workshop disappears and the average concentration of pollutants in the workshop decreases.(4)Optimize the air supply mode of the original workshop.In the upper air supply mode,the concentration of VOCs at the workshop station is far lower than that under the side air supply condition,which meets the requirements of the specification.