Citrate In The Treatment Of Low Concentrations Of Sulfur Dioxide In Flue Gas

Sulfur dioxide is one of the main gas which cause air pollution. With theenforcement of people's consciousness of environment and more restrictivesulfur dioxide emission, treatment of sulfur dioxide flue gas has become animportant and imperative task.Citrate method is a new method for the separation of sulfur dioxide influe gas, it has been used in treating high content sulfur dioxide flue gas,but the use of it in treating flue gas with high oxygen content and low sulfurdioxide content is not reported. The use of citrate solution in removal ofsulfur dioxide is investigated, and the pilot-plant-scale test is carried out inJin Dui Cheng refinery plant.The results show:(1)The solution of citrate is a satisfying absorbent for flue gas. Themaximum capacity is 105g/L.(2)The capacity of citrate solution and SO₂ removal efficiency aredependent on the concentration of citric acid and pH .The higher theconcentration of citric acid and pH is, the capacity is larger and theabsorption rate is faster.(3)The desorption efficiency of SO₂ is related with the concentration ofcitric acid and pH. The lower the concentration and pH is, the efficiency isbigger an4 the rate is faster.(4)The optimum ingredients of absorbent are: pH 4.5 5.0,concentration of citric acid: l .0mol/L. In this case, the maximum efficiencyis obtained.(5)The increase rate of SO.'- is 0.2g/L-'. h-'. Special process must beinstalled to discharge SO.'-.(6)Concentration of SO.'-can be reduced to l 5g/L when the temperatureof solution is 0'C and the state lasts for 4 hours.