Simultaneous wet absorption of SO2 and NOX with mixed Na2SO3 and (NH4)2SO3: Effects of mass concentration ratio and pH

Wet flue gas desulfurization is considered as one of the most effective methods for the simultaneous removal of NOX and SO2 in the flue gas. To investigate the absorption performance of NOX and SO2 with the absorbents of Na2SO3 and (NH4)2SO3 and study the controlling factors of the process, the sulfite-based mixed absorbents with different mass concentration ratios of Na2SO3 to (NH4)2SO3 are employed for the gas removal in a bubble absorber. The results indicate that the absorbents have high absorption efficiency for SO2 and NO2 (all over 93%) with different mass ratios of Na2SO3 to (NH4)2SO3, and the absorbent with the proportion of 50%: 50% has the highest removal efficiency for NO (73.8%). The pH of the absorbent solution is a controlling factor affecting the absorption performance, and the alkaline condition is more conducive to absorption. The more the content of (NH4)2SO3 is, the lower the pH value and SO2 absorption amounts are. Moreover, the absorbent with a ratio of 30%: 70% has the highest removal efficiency (99.6%) and also the highest absorption amount (2761 mg/100 g) of SO2 (when the initial pH is the same). For the simultaneous absorption of NOX and SO2, the absorbent with a ratio of 30%: 70% has the highest removal efficiency (64.3% for NOX and 99.5% for SO2).

Automated summary

Wet flue gas desulfurization using sulfite-based mixed absorbents has shown high absorption efficiency for SO2 and NO2. The alkaline condition is more conducive to absorption, and the absorbent with a ratio of 30%: 70% shows the highest removal efficiency for both NOX and SO2.