烟气生物脱硫污泥中单质硫的回收工艺中试研究

Pilot Studies on Reclamation Process of Elemental Sulfur from Flue Gas Biodesulfurization Waste Sludge

针对烟气生物脱硫污泥中单质硫磺难以回收和利用的问题,研究设计了一条以有机溶剂四氯乙烯(PCE)高温萃取-降温结晶技术为主体工艺的路线。经过几个月的中试研究表明,PCE萃取工艺是一种有效的回收硫泥中单质硫磺的方法,得出如下最优的运行参数:干燥后的硫泥粉碎到粒径0.05～0.15mm(100～300目)、接触反应时间为10～15min、接触反应的温度范围85～100℃,PCE与硫泥的投加比例为4～5mL/g,降温结晶至25℃以下。试验结果表明,回收的硫磺纯度在96.5%以上,硫的回收率在90%以上。最后从所需蒸汽费、冷却水费、电耗费、人工费、PCE消耗费等几个方面对该工艺应用于拟建的硫回收工程进行了经济效益分析,拟建工程的运行成本为230元/t,净收益为770元/t,年收益可达到281万元,可产生可观的经济、环境和社会效益。

In order to reclaim valuable elemental sulfur from flue gas biodesulfurization waste sludge, this study developed a process that mainly consisted of two unit operations of high temperature perchloroethylene （PCE） extraction and low temperature sulfur recrystallization. The results of pilot study indicated that the PCE extraction was an effective method for the sulfur recovery from the biodesulfurization sludge. The optimal parameters were the dried sludge with particle size of 0.05 - 0.15 mm, the contact time of 10 - 15 min, the extraction temperature of 80 - 100℃, the PCE-to-sludge ratio of 4.0 - 5.0 mL of PCE per gram of sludge, the recrystllization temperature of less than 25℃. The recovered sulfur generally had purities higher than 96.5%, and the sulfur recovery efficiency were higher than 90%. Economic analysis results indicated that the total costs of the proposed reclamation process that included steam, cooling water, electricity, PCE consumption, and labor was about ￥230/t of sulfur reclaimed. Therefore, the net earnings would be ￥770/t and the annual earnings would be ￥2.81million. The results indicated that the PCE extraction was an effective and economical method for the sulfur recovery from the biodesulfurization sludge.