Research On Self-suctioning Water Mist Technology For Fire Extinguishing In Coal Fires

Coal fire is a worldwide disaster,and water mist is an effective measure to control coal field fires.In order to improve the applicability of water mist technology in the control of coal fire,this paper proposes the self-suctioning water mist generator,operation simple and a high degree of atomization.It analyzes the design principle of the atomization device,and verification shows that the fire-extinguishing performance and cooling effect of the self-suctioning water mist generator in the high temperature fire zone,to provide technical reference for the efficient treatment of coalfield fire.Based on the elaborate analysis of the characteristics of coalfield fire and water mist fire suppression,this paper gives full play to the advantages of water mist fire suppression,and proposes the design principle of self-suctioning water mist generator from the aspects of power facility ies,atomization characteristics and working environment,and formulates the design scheme of the atomization device including the atomization method,the main body form and the suction method.In order to further optimize the structural parameters of the self-suctioning water mist generator,the numerical simulation method is used to analyze velocity flow of the atomizing device's gas-liquid phase.The influence of different structural parameters?including multihole nozzle diameterd_n,air-suction hole diameterd_s,air-suction hole angleband the throat length-diameter ratiol d_t?on the velocity flow is obtained,and the optimal structural parameter range of the atomization device is determined.Based on the numerical simulation results by Fluent,this paper designs the atomization characteristics experiment of self-suctioning water mist generator,analyzing the variation of droplet diameter D₃₂,droplet velocity V_out and atomization angleawith different structural parameters and working conditions pressure.It also makes an exposition of the principle and process of atomization device.After optimization analysis based on theoretical,numerical simulation and atomization characteristics experiments,an efficient two-phase flow atomization device of medium-pressure and no external air source is developed,which can produce small droplet diameter,large exit velocity,uniform mist flow and large atomization angle.In order to verify the fire-extinguishing performance of the self-suctioning water mist generator,the water mist experimental system is designed to conduct an experimental study on the process of extinguishing high-temperature combustible coal fire in a confined space.The analysis is carried out on the effect of water mist extinguishing and cooling under the two fire suppression methods of coal pile and non-positive coal pile fire source.Besides,the fire extinguishing and cooling effect of atomization device is investigated by comparing the water injection fire extinguishing experiment and the field application.Experiments show that water mist has a good effect of heat absorption and putting out the flames,and can achieve quickly fire suppression by diffusion in a confined space.At the same time,compared with the traditional water injection treatment technology,the water cooling efficiency is effectively improved,and rapidly cooling of coal fire is realized.In short,it provides a reference for the design of water mist fire extinguishing technology and its application in coalfield fires.