Principles And Methods Of Pollutant Ventilation Control In Column Confined Space

Using high-efficiency ventilation technology to improve the control efficiency of pollutants is a key technology for industrial buildings to improve the internal environmental quality and energy saving.Especially in tunnels,mines and pressure vessels welding or ventilation control of industrial operations in special restricted spaces.Factors such as jet flow field distribution,pollutant control,restricted space shape and size during ventilation will affect the ventilation effect of the operation.Therefore,in order to improve ventilation efficiency and reduce energy consumption,it is necessary to conduct in-depth research on the control principles and methods of such confined space pollutants,and put forward reasonable improvement measures.In this paper,the principle and method of pollutant control in columnar confined space are studied through numerical simulation and experimental verification.The specific contents include the following aspects:First,the definition of the columnar confined space is given,and at the same time,the reasons for the contaminant retention in the confined space are explored,and then the method to eliminate the adverse vortices is studied to achieve the effectiveness of the flow field characteristics of the jet restricted space Control the purpose of meeting the actual needs of the project.Second,through the numerical simulation of six cylindrical confined space vortex elimination methods,including progressive diversion vortex elimination,split diversion vortex elimination,stepped diversion vortex elimination,combined structure vortex elimination,U-shaped structure elimination and The orifice plate eliminates vorticity and obtains the change law of its influence on the flow fieldcharacteristics of column-shaped confined space and the residence time of pollutants.By reducing the influence range of the vortex zone,the drag loss is reduced,and the residence time of contaminants in confined spaces is shortened..Thirdly,a new type of air flow organization method that can fundamentally solve the problem of pollutant retention-vortex jet ventilation is proposed,and its five important parameters including the size of the air supply opening,the number of air supply openings,the shape of the air supply opening,and the air supply are investigated by numerical simulation The effects of turbulence and exhaust characteristics give ideal conditions for the formation of cylindrical air vortices.The results show that the generation and distribution of cylindrical air vortices have nothing to do with the turbulence of the air supply and the number of air outlets,but the asymmetric air supply boundary will make the stability of the vortex ventilation poor;at the same time,it is found that the vortex jet ventilation intensity As the size of the air supply,the width-to-height ratio of the air supply opening,and the size of the air discharge opening decrease,the pollutant particles are more easily discharged at this time.Fourth,for the traditional restricted space jet,a series of vortex elimination devices were developed and performance tests were conducted.It is found that the vortex elimination effect of the uniform diversion orifice plate is the best regardless of whether the ventilation method is only blowing or blowing and combining,and the uniform diversion orifice plate has 8 opening rings and an opening rate of 55.%,The vortex elimination effect when placed at the front of the restricted space is the best and most recommended,providing a feasible solution for improving the working environment of workers.Finally,a preliminary test was carried out on the vortex jet ventilation smoke tracing experiment of a new air flow organization method.This ventilation method not only improves the ventilation efficiency of the restricted space,but also will not produce a vortex area inside the restricted space.A new type of ventilation with development prospects.