Oxidation inhibition of sulfite in dual alkali flue gas desulfurization system

A laboratory-scale well-mixed thermostatic reactor with continuously blasting air was used to investigate the oxidation inhibition of sulfite in dual alkali flue gas desulfurization （FGD） system. The effects of operating parameters such as pH value and catalyst concentration on the oxidation were studied. Sodium thiosulfate was used in the system, and was found that it significantly inhabited the sulfite oxidation. In the absence of catalyst, sodium thiosulfate at 12.67 mmol/L had an inhibition efficiency of approximately 98%. While in the presence of catalyst, sodium thiosulfate at 26.72 mmol/L had an inhibition efficiency less than 85.0%. The oxidation reaction order of sulfite in the sodium thiosulfate was determined to be -1.90 and 4）.55 in the absence and presence of the catalyst, respectively. Apparent activation energy of oxidation inhibition was calculated to be 53.9 kJ/mol. Pilot tests showed that the consumption rate of thiosulfate agreed well with the laboratory-scale experimental results.

Experimental and Theoretical Studies on Desulfurization Efficiency of Dual-alkali FGD System in a RST Scrubber

The effects of operating parameters on desulfurization efficiency of a dual-alkali FGD process in a rotating-stream-tray(RST)scrubber are investigated.A dimensionless factor,ε,is proposed in this study to predict desulfurization efficiency of this dual-alkali FGD system.ε represents the desulfurization ability of a dual alkali FGD system,determined by five main operating parameters such as sodium ion concentration,ratio of absorbent flow rate to flue gas flow rate,pH value of absorbent solution,ratio of sulfate ion to total sulfur ion in absorbent solution,and sulfur dioxide concentration of inlet flue gas.The empirical expression for predicting desulfurization efficiency at different temperatures is obtained through the experimental study and theoretical calculation.It provides useful guide for engineering design.