Stable flow characteristics of Geldart C particles of desulfurization ash in a loop-coupled riser
The proportion of CO2 emissions for industrial production is about 70%of the total CO2 release.It is important to capture this part of the CO2 emission for carbon peaking and carbon neutrality goals.Flue gas emissions contain a large amount of oxides of sulphur which are harm to the facilities and catalysts.Therefore,deep desulfurization technology of flue gas is key to CO2 capture process.Circulating fluidized bed semi-dry flue gas desulfurization has attracted wide attention because of its high desulfurization efficiency,no pollution,and controllable residence time.The desulfurization agent in the circulating fluidized bed is mostly desulfurized ash particles which are obviously Geldart C particles.Due to the desulfurized characteristics like strong adhesion,problems are prone to occur during the operation of the fluidized bed.To improve the fluidization situation,this research designed and built a loop-coupled riser reactor with an inner diameter of 100 mm,300 mm in height,an inner diameter of an outer cylinder of 160 mm,760 mm in the height,and a conveying section of 75 mm in inner diameter and 12.6 m in height.Under two operating conditions,namely Ug=4 m/s,Gs=45 kg/(m2·s)and Ug=7 m/s,Gs=25 kg/(m2·s),the pressure distribution,standard deviation and power of the pressure were investigated.It can be considered that when the gas velocity in the annulus zone is 0.4 m/s,the circulation flow in the loop part can reach stable with a continuous dense-phase flow.Then,the distribution of particle flow characteristics including solids holdup and particle velocity in the loop-coupled riser reactor was studied.Experiments have found that the design of circulating flow can strengthen the flow characteristics of Geldart C particles,greatly increase the solid content of Geldart C particle desulfurization ash in the coupling reactor,and achieve stable operation of the Geldart C particle circulation fluidization device.Meanwhile,these results may provide some guide for design new types of reactors for Geldart C particle of emission control.
circulating fluidized bedmultiphase reactorfluid mechanicsdesulfurization ash particlesGeldart C particleloop-coupled reactor
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