Preliminary Experimental Study Of The Application Of Fly Ash Pneumatic Conveying Technology To Fill The Goaf

As our country's important energy pillar,about billions of tons of coal were excavated every year.However,with the underground mining,goaf caving caused different degrees of influence and destruction to the ground surface,including surface subsidence,damage to the environment and many other effects,causing a lot of economic and social problems.In recent years,the filling technology to the coal goaf has become an important trend in the development of coal technology.The pneumatic filling means conveying the powder bulk material to the goaf by pipelines,having the air stream with a certain pressure and the initial velocity as the power source.The pneumatic filling adopts pneumatic conveying technology for material transportation,and this paper focuses on the experimental study of the positive pressure dense phase pneumatic conveying system for bin type pump,using fly ash as the conveying material.Furthermore,it elementarily analyses the related law of the conveying process.And the main research are as follows:1.Analyse the basic flow pattern of pneumatic conveying and focus on the research of group flow,whose flow characteristics are mainly studied in experiments;2.Show the commonly used parameters in pneumatic conveying and explore the inherent law by calculating and analysing the relevant parameters;3.Study the dense phase conveying mechanism based on the stress analysis of a solid particle;4.Make a double factor analysis of the gas flow and pressure in the experiments,using fly ash as the material,to study the related factors that affect pneumatic conveying system,to explore the relation between output and powder gas ratio,to master the law of pressure and flow variation with time in the conveying process,to find out the optimal parameters and system configuration of the experimental system,to analyse the effects of pressure loss on system conveying to understand the basic methods to reduce the pressure loss;5.Analyse the flow pattern of two-phase flow by using electrical capacitance tomography technique to measure the whole experimental process;study the gas solid two-phase concentration distribution and internal flow pattern on the cross-sectional and longitudinal section of the system,based on the real-time image analysis,to validate the experimental results.To sum up,this paper studies the related parameters of the pneumatic conveying process through theoretical and experimental analysis to obtain the basic law of gas solid two-phase flow in the pneumatic conveying process.Furthermore,the study proposes the optimal parameters and system configuration so as to improve the transportation efficiency and reduce the waste of energy resource.