Performance Of SO₂ Absorption By Basic Aluminum Sulfate Solution At Constant Temperature And SO₂ Desorption By Rich Desulfurization Solution Under Negative Pressure

In recent years,with the increasing shortage of energy and the gradual improvement of SO₂ emission standard,it was particularly important to find a renewable SO₂ flue gas desulfurization technology.The desulfurization method of basic aluminum sulfate?aluminum base?had a good comprehensive performance such as high desulfurization rate,recyclable desulfurizer,non-toxic,and not easy to block equipment under acidic conditions,so it had broad application prospects.In order to maintain high desulfurization efficiency,aiming at the problems such as high cooling cost of desulfurization rich liquid caused by low desulfurization temperature,poor thermal desorption performance at atmospheric pressure and easy oxidation of desulfurization products,the desulfurization performance at different absorption temperature,desorption performance at different pressure and temperature,and alternative cycle desulfurization-desorption performance with oxidation inhibitor were studied.On the self-made constant temperature absorption and desorption experimental system,the influence of desulfurization temperature on SO₂ absorption and desulfurization rich liquid temperature on SO₂ desorption was studied.The results showed that the higher the temperature of aluminum base solution,the faster the decrease in absorption performance and the increase in desorption performance.When the temperature changed from 20?to 60?,the absorption rate decreased by 7.33%,the oxidation rate increased by 2.75%,and the time to maintain the absorption rate above 95%was shortened by 27min during the 40min absorption process.However,during the120min desorption process,desorption rate increased by 29.19%,and oxidation rate decreased by 1.96%.The effective absorption temperature was preferably below 40?,and could be extended to the range of 40-50?,which had important guidance for engineering design and practical application.The effects of pressure,temperature and solution boiling on the desorption performance of SO₂ were studied on a self-made desorption experimental system of negative pressure.The results showed that decreasing pressure or increasing temperature was beneficial to increase desorption rate of SO₂ and reduce oxidation rate of SO₃^2-.When the desorption temperature was 60?and 91.1?,the desorption rate of 75k Pa was at least 4.92%and 22.3%higher than that of 90k Pa,and the oxidation rate of desorption end point was 3.18%and 2.46%lower.The time for the negative pressure boiling to reach the relatively stable stage of desorption required a maximum of 40minutes and a minimum of 22 minutes,which was 8 minutes and 26 minutes shorter than normal pressure boiling.The oxidation rate of SO₃^2-in both negative pressure boiling and normal pressure boiling reached the maximum within 2 minutes,and compared with that in normal pressure boiling,the oxidation rate in negative pressure boiling decreased by2%.Desorption pressure was not the lower the better,there was a suitable combination of desorption pressure and temperature.Furthermore,the performance of alternative cycle desulfurization-desorption was examined by adding selected oxidation inhibitors.The results showed that ascorbic acid was the best oxidation inhibitor,and the best concentration was 5mmol/L.The addition of oxidation inhibitor could effectively inhibit the increase of SO₄^2-and and delay the start of decline of high-efficiency absorption rate,which was helpful to reduce the attenuation of aluminum base absorption performance.And then,the multi cycle absorption-desorption performance of aluminum base was improved and the SO₂absorption capacity of 5 cycles remains stable.Under the same other conditions of cycles,the increase of SO₂ desorption rate mainly depended on the addition of oxidation inhibitor and its concentration.However,the number of cycles had little effect on the desorption rate,and the desorption rate of 10 cycles could reach over 97.6%.