Comparison of Acid Gas Control Technologies in EFW Facilities

As Energy-from-Waste (EfW) facilities make the leap into the twenty-first (21^st) century, so does the demand for cost efficient air pollution control technology. In an effort to meet this rising demand, companies have to develop concepts that remove acid gases in an efficient, sustainable, and reliable way. The current market trend to provide the best available control technology (BACT) leads people searching for technologies that are: • Proven and have extensive records of success. • Highly efficient, resulting in low emission to the atmosphere, but requiring minimal investment. • Compact in design, simple, and low maintenance. • Offering high availability, low reagent consumption, and low residue levels. • Resulting in either clean or suppressed liquid effluents. This paper will specifically discuss the three main types of acid gas control technologies available in today’s marketplace, which include dry, semi-dry, and wet scrubbers. It will first focus on the acid gas control technology most commonly used in the US, the spray dryer absorber, followed by a typical Ring Jet® wet scrubber with packed bed, and finally, the Turbosorp® system. For each of the above technologies, this paper will present the concepts, advantages and disadvantages, achievable emissions, and capital and operating costs. It will then look at how each of these technologies is utilized at existing EfW facilities operating throughout the world and provide information on how each facility has been operating. Lastly, it will look towards the future of acid gas control technologies and provide insight into what advances are being made to meet the most stringent air emission regulation all over the world.