Study On Semi-Coke Particles Flue Gas Desulfurization Technology In Spouted Bed

The emission of SO₂had inflicted severe acid rain pollution, air pollution, along withthat it is so regrettable for China such a country with a lack of sulfur in which gigantic sulfurresources had been wasted. So, Exploiting R&D of flue gas desulfurization and recoverytechnology had been becoming one of urgent requirements for the sustainable development ofliving environment. Semi-cokes flue gas desulfurization technology which possessedupstanding potential application can desulfur form flue gas, and simultaneously with drawalsulfur resources. In this paper, a new type carbon method flue gas desulfurization processcombined with spouted bed technique to remove SO₂from flue gases is presented. It canachieve the purpose of disposing the waste by waste using semi-cokes separated from flue gasof the tiered burning boilers as desulfurization sorbent.The mainwork in present paper can be summarized into these parts as follows:In this paper, the key problem of flue gas desulfurization technology in a spouted bedusing semi-cokes was studied through hydrodynamic experiment and hot mold experiment etc.This paper examined on hydrodynamic behaviour and its desulphurizing ability of semi-cokesin a spouted bed. The developed model of heterogeneous reactions including the two-fluidmodel （TFM） was also used to predict the process of flue gas desulphurization in a spoutedbed using semi-coke particles. The results of this paper can offer some technical reliance andguidance for industrialization of semi-cokes flue gas desulfurization technology in a spoutedbed.The radius distribution, specific surface area and volume of micropore in semi-coke wereresearched by N2isothermal adsorption/temperature-programmed desorption method and HKmethod. The pore channel of semi-cokes was observed as long and narrow by scanningelectron microscopy （SEM）. And, the SO₂, O2,H2O and SO3interaction profiles along theradial direction inside the micropores of semi-cokes have been calculated based on theLennard-Jones potential function. And, the minimum adsorption potential of SO₂, O2, H2Oand SO3were obtained. The result shows that the ability of absorbing SO₂of semi-coke wasequivalent to75%of adsorption characteristics of activated carbon particles. Therefore,semi-cokes had been successfully developed in substitution of activated carbon for removalSO₂in the flue gas. The behavior of a gas-solid flow in a spouted bed was obtained through thehydrodynamic experiment and numerical simulation. Including the change pattern of bedpressure drop, the minimum spouting velocity, the gas velocity of central spout region,spouted diameter and the particle velocity of annulus. The average of solid concentrationdistributions in annulus area was predicted by using the core-annulus model incorporated theexperiment data. The solid concentration of annulus decreases with bed height increase, withthe gas velocity decreases. The simulation results were good agreement with experimentalresults. And, that will be based on the simulation of semi-coke flue gas desulfurization inspouted bed.The maximal total pressure drop and the minimal spout velocity of spouted bed wereobtaind by different operating conditions, and estimating the distribution of the axialsuperficial gas velocity and the gauge pressure. The results calculated by model of Mathurand Gishler were good agreement with the experimental results, especially for range ofpacked height between250mm and350mm. The experimental study on the particle massloss rate at dieffrent conditions was perofmred. The result shows that the increase of packedheight can improve the loss rate of the particle mass.A hot-state experiment study has been performed. The results reveal that the heat transferperformance and desulfurization efficiency of spouted bed is better than packed bed. It can beseen that the unique flow structures in a spouted bed are advantageous for enhancingdesulfurization. The tests also showed that the rate of desulphurization have peak profileswith increase of superficial gas velocity. And, the functional dependence between theoptimum gas velocity and the superficial gas velocity is,U mx1.23¹.45Ums. Based onthe experimental study on the rate of desulphurization at diffetent packed height conditions,the desulfurization efficiency can be markedly improved by increase of packed height in aspouted bed.In this work, TFM, which includes KTGF and chemical reaction kinetics, was extendedto simulate the desulphurization process in the spouted bed with semi-coke particles. Particlescollision and fluctuation in a bed can be described by KTGF. The complicateddesulphurization process includes a system of5species and6chemical equations.Heterogeneous reaction rates were determined by Langmuir-Hinshelwood-type mechanismincorporated the Arrhenius law.With proposed model, the process desulphurization using semi-coke particles were obtained, and the overall flow patterns within the spouted bed werepredicted well by the model, i.e. formation of a stable spout region, a fountain region and anannular region were correctly predicted. The results showed the distribution of concentrationof SO₂in a spouted bed. Besides, the effects of reaction temperature along with H2O, O2content in the flue gas on the desulphurization efficiency were investigated to determineoptimum operating conditions. Value of experimental determination dovetailed better withmodeling value. The results of paper offered clues for optimum design of reactor and researchof flue gas desulphurization using semi-cokes in a spouted bed.