Study On Multiphase Flow And Mass Transfer Characteristics In The Liquid Chamber Of Syngas Scrubbing Tower

Air pollution caused by coal combustion is becoming more and more serious.Nowadays,coal gasification leads the development direction of clean coal technology.The syngas produced by coal gasification often contains small particles of fly ash,which will have adverse effects on the environment and the subsequent utilization of syngas.In industry,scrubbing tower is used to capture fly ash particles.The liquid chamber at the bottom of scrubbing tower is a kind of casing type water-bath dust collector and involves gas-liquid-solid three-phase flow.It plays as a role of pre-dedusting and has great influence on improving the overall gas-solid separation ability of scrubbing tower.Therefore,it has important theoretical significance and engineering application value to study the flow behavior and separation characteristics of gas-liquid-solid three-phase in the liquid chamber.In this paper,the flow process of gas-liquid-solid three-phase in the liquid chamber was studied by using VOF coupled DPM model based on computational fluid dynamics(CFD)method.Gas holdup and wetted perimeter were used to characterize the dispersion and mixing of gas-liquid two-phase.After these two phase became steady,spherical fly ash particles with Rosin-Rammler size distribution were injected.In the liquid chamber,the movement,concentration distribution and removal efficiency of these particles were investigated.Moreover,based on the capture mechanism of particles,the main areas where mass transfer occurs in the chamber were determined,and two optimization directions for enhancing mass transfer effect were proposed.In order to improve the gas-solid separation effect,the influences of different gas inlet velocities,liquid level heights and guide pipe diameters were studied respectively.The optimal parameters were obtained.Finally,the flow field distribution,particle movement and removal ability under three kinds of gas intake modes were compared comprehensively.This work provides a reference for the design and optimization of impact water-bath dust removal equipment.