Experimental study on SO2 recovery using a sodium-zinc sorbent based flue gas desulfurization technology

• Published in: Chinese journal of chemical engineering Vol. 23; no. 1; pp. 241 - 246
• Main Authors: Zhang, Yang, Wang, Tao, Yang, Hairui, Zhang, Hai, Zhang, Xuyi
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2015
• Subjects: Flue gas desulfurization; Na2CO3; Na2SO3; SO2 co-production; SO2吸收; Sodium–zinc sorbent based; Waste treatment; ZnSO3·2.5H2O pyrolysis; 半干法烟气脱硫; 实验; 烟气脱硫技术; 热分解特性; 硫酸钠溶液; Sodium–zinc sorbent based; ZnSO3·2.5H2O pyrolysis; Flue gas desulfurization; SO2 co-production; Waste treatment
• ISSN: 1004-9541; 2210-321X
• DOI: 10.1016/j.cjche.2014.10.007

A sodium–zinc sorbent based flue gas desulfurization technology（Na–Zn-FGD） was proposed based on the experiments and analyses of the thermal decomposition characteristics of Ca SO3 and Zn SO3·2.5H2 O, the waste products of calcium-based semi-dry and zinc-based flue gas desulfurization（Ca–SD-FGD and Zn–SD-FGD） technologies, respectively. It was found that Zn SO3·2.5H2 O first lost crystal H2 O at 100 °C and then decomposed into SO2 and solid Zn O at 260 °C in the air, while Ca SO3 is oxidized at 450 °C before it decomposed in the air. The experimental results confirm that Zn–SD-FGD technology is good for SO2 removal and recycling, but with problem in clogging and high operational cost. The proposed Na–Zn-FGD is clogging proof, and more cost-effective. In the new process, Na2CO3 is used to generate Na2SO3 for SO2absorption, and the intermediate product Na HSO3 reacts with Zn O powders, producing Zn SO3·2.5H2 O precipitate and Na2SO3 solution. The Na2SO3 solution is clogging proof, which is re-used for SO2 absorption. By thermal decomposition of Zn SO3·2.5H2 O, Zn O is re-generated and SO2 with high purity is co-produced as well. The cycle consumes some amount of raw material Na2CO3 and a small amount of Zn O only. The newly proposed FGD technology could be a substitute of the traditional semi-dry FGD technologies.