Flow And Mass Transfer Characteristics And Scale-up Effect In A Countercurrent Cross-flow Scrubber

With the development of modern industry,large amounts industrial waste gases containing NO_X,SO_X and CO₂ inevitably increase.The Wet Flue Gas Desulfurization is an effective method for purifying the above industrial waste gases.Recently,a new countercurrent gas-liquid scrubber assembled with well performed washing nozzle was proposed.This kind of scrubber has high washing efficiency and adapts to various operating conditions.The effects of operating parameters on the flow pattern,pressure characteristics,gas hold-up distribution and mass-transfer characteristics of the countercurrent gas-liquid scrubber were investigated through cold model experiment via the dissolved oxygen method,the double-sensor conductivity probe and the pressure sensor method respectively to reveal their relationship.The optimal structural parameters of the nozzle were determined at first.With scrubber's size changing,the experimental results indicated that the optimal structural parameters of the nozzle should be changed to adjust to it.Axial pressure distribution and radial pressure distribution were investigated through the pressure sensor.Gas hold-up distributions were investigated through the double-sensor conductivity probe.Then the relationship of gas hold-up distribution to the pressure distribution was revealed.The results signified that pressure was mostly provided by gas phase where pressure rose/dropped with gas hold-up,or that pressure was mostly provided by liquid phase.In order to study the hydrodynamics characteristics,the experiment procedures were carried out in three different scrubber internal diameters including 100mm,140mm and 170mm,respectively.It was found that experimental results in 100mm and 140mm scrubber were similar to each other;however,it showed many distinct differences from those in 170mm scrubber.In addition,scrubber's pressure drop was calculated and a two-stage model for the countercurrent gas-liquid scrubber oxygen desorption process was established based on the surface renewal and other theories.The computed results by this model are in good agreement with the experimental results,so the conclusions are useful to the design and industrial application of scrubbers.