Desorption Performance Of Flowing Basic Aluminum Sulfate Desulfurization Rich Liquid Under Microwave Irradiation

Exploring high-efficiency and energy-saving desulfurization methods for SO₂emission control and resource utilization of coal-fired flue gas has always been the focus of research at home and abroad.Basic aluminum sulfate（aluminum base）regeneration desulfurization technology has attracted extensive attention because of its large SO₂absorption capacity,high desulfurization efficiency,renewable aluminum base and rich production of high-purity SO₂.In the desulfurization of aluminum base regeneration,the traditional heating method was mostly used in the past,and there were problems such as long heating time and low desorption rate.To solve these problems,using the special effect of microwave,a dynamic microwave desorption device was used to study the desorption effect under different dynamic desorption process parameters,and the macro desorption performance was obtained.Further,combined with the mass transfer theory,the mass transfer characteristics under different working conditions were obtained,and the micro mechanism of microwave enhanced mass transfer was explained.The macro desorption performance showed that the dynamic microwave desorption system operated stably,and the temperature in the desorption bottle could be maintained at the target temperature under the continuous action of microwave.At the same time,the temperature of the desorption solution in the buffer bottle could be kept at a low level to exclude the influence of heat other than microwave desorption.High microwave power and initial concentration of desulfurization rich solution significantly promoted the desorption performance.The desorption ratio at the desorption end point reached more than 72.26%and 71.64%,the desorption rate reached above 1.8745×10^-4 mol·L^-1·min^-1and 2.4435×10^-4mol·L^-1·min^-1.High microwave power showed significant microwave desorption non-thermal effect,which was characterized by fast heating and desorption rate and high desorption ratio.Under the condition of high flow rate,the circulation ratio of desulfurization rich liquid was increased,which prolonged the effective action time of microwave,and then improved the absorption ratio and desorption rate.Under the condition of high desulfurization rich liquid concentration,combined with microwave action and high flow rate,the desorption ratio and desorption rate could be greatly increased.Under the conditions of initial concentration 0.1534 mol/L,flow 450 ml/min and microwave power 800W,the desorption ratio could reach 86.64% and the average desorption rate was 1.8666×10^-3 mol·L^-1·min^-1。The micro desorption mass transfer showed that under a certain desulfurization rich liquid flow rate,the volumetric mass transfer coefficient increased with the increase of microwave power,and the higher the microwave power was,the more obvious the increase was.As a result,the volumetric mass transfer coefficient at 800 W microwave power increased by 77.81%compared with that at 500 W.The increase of initial concentration and flow rate of desulfurization rich solution led to the increase of volumetric mass transfer coefficient,and the effect of initial concentration was much greater than that of flow rate.In the single factor comparison,when the initial concentration and flow rate of desulfurization rich liquid were increased,the volumetric mass transfer coefficient was increased by 53.99%and 12.77%respectively.Although the enhancement of mass transfer effect was not obvious by simply increasing the flow rate,it could be further improved when combined with high microwave power.At 800 W microwave power,the volumetric mass transfer coefficient further increased by 13.57%with the increase of desulfurization rich liquid flow.The important value of microwave desorption was that the special effect of microwave could significantly promote the desorption mass transfer performance under low desulfurization rich liquid concentration.Further cooperation with dynamic circulation could realize the efficient,continuous and stable operation of desorption process.