Study And Optimization Of Key Flow Passage Components In Dense Phase Pneumatic Conveying System Of Pulverized Coal

Based on the background of the pulverized coal entrained flow gasification process,the numerical approach of computational particle fluid dynamics(CPFD)was applied to study the key components such as vertical pipe,bend pipe and variable cross-section pipe fittings commonly used in pneumatic conveying system.Then the gas-solid two-phase flow characteristics of the regulating valve of pulverized coal with complex flow channels were investigated.Finally,some suggestions are provided for the pipeline layout and structure design of the regulating valve with the help of this method.The details are as follows.The vertical pipe and bend pipe in the 50 mm industrial-scale pulverized coal conveying system,and the venturi in the 15 mm high pressure pulverized coal conveying system independently built in the laboratory were taken as the research objects.Firstly,the applicability of CPFD method of key pipe fittings in dense phase pneumatic conveying system was proved.Then the internal flow characteristics of vertical pipe with different working conditions,and the influence of the bending arrangement and the curvature radius of bend pipe on the conveying system were studied,respectively.Finally,the CPFD was used to assist the structural design of industrial venturi.Taking the regulating valve of pulverized coal in a pulverized coal gasification conveying system as the research object,its flow characteristics and pressure drop characteristics were studied firstly.Then the process of pulverized coal flow through the pulverized coal flow regulating valve with complex flow channel is visualized with the help of the numerical method.And the gas-solid two-phase flow characteristics such as pressure,particle velocity and solid mass concentration of the regulating valve were analyzed emphatically.Finally,the relationship between regulating valve pressure drop,pulverized coal flow rate and opening was obtained by CPFD approach.The aim is to provide some reference for the pipeline layout and structure design of the regulating valve of pulverized coal.Firstly,the relationship between the maximum particle velocity in the flow channel and the valve opening and the particle velocity distribution at the valve plug outlet were studied in order to provide some suggestions for the suitable valve opening.Then the distance to stabilize the characteristic parameters of gas-solid two-phase flow downstream the regulating valve was analyzed to reduce the wear of the bend pipe after the valve.Finally,four kinds of valve plug structures were explored and studied for improving the flow of pulverized coal in the valve plug and reducing the phenomenon that the foreign body falls into the spool and cannot be discharged.