Study On Desulfurization Characterristic Of Solid Adsorbent For Low-Temperature Flue Gas

For low-concentration SO₂ flue gas,the wet and semi-dry desulfurization processes have problems such as large water consumption and complex equipment,while the dry fixed-bed adsorption desulfurization process has the characteristics of less water consumption,simple equipment and stable operation process.However,the existing desulfurizers on the market with calcium hydroxide or calcium oxide as the main body have the problems that the calcium utilization of the adsorbent is low and the replacement cost of the desulfurizer is high.Therefore,the purpose of this study is to prepare an adsorbent with high utilization,low cost and simultaneous desulfurization and denitrification under the condition of low temperature and low concentration sulfur dioxide flue gas.The research shows that some studies on desulfurization of alkali-containing wastes have achieved good results.In this study,carbide slag,red mud,fly ash and steel slag were selected as raw materials to prepare adsorbents.The composition and proportion of the adsorbent and the preparation process were optimized by the control variable method.The research results showed that when the red mud,fly ash and carbide slag were mixed under the condition of mass ratio of 3:1:1,The desulfurization efficiency of the adsorbent obtained under the conditions of 4 hours,drying temperature of 80°C,and drying time of 6 hours is 5-6 times higher than that of single raw material adsorbing sulfur dioxide.Further tests on a small fixed bed,the reaction conditions are SO₂ concentration 800≤C≤2400 mg/m³,temperature 40≤T≤100℃,relative humidity 0.4≤RH≤0.6,and it was found that the SO₂concentration had a significant effect on the adsorbent.With the increase of temperature,the utilization of the adsorbent decreases slightly,but still remains above 80%;when the relative humidity is below 40%,the utilization of the adsorbent is Below 30%,when the relative humidity is between 0.4-0.6,the utilization of the adsorbent increases rapidly,and after more than 60%,the relative humidity does not significantly improve the utilization of the adsorbent calcium.The material composition and pore structure characteristics of the reacted and unreacted adsorbent were analyzed by XRD,BET and SEM,and it was determined that the reason for the better desulfurization reaction performance of the adsorbent was the reasonable pore size distribution,the promotion effect of iron oxide and the concentration of high activity substances.By analyzing the effect of temperature on the breakthrough curve,it is determined that the improved shrinkage core model is used to fit the data of the reaction control stage to obtain the reaction activation energy and reaction rate constant.The product layer diffusion control stage of the adsorbent desulfurization reaction was simulated by the equivalent particle model,and the effective diffusion coefficient and reaction activation energy were obtained.