Elsorb process

Elkem Technology s Elsorb process is similar to the WeUman-Lord process however, it employs a different solvent. An aqueous solution of sodium phosphate is used. 

Alkali Metal Sulfite-BIsulfite (Wellman-Lonl) Process, 554 ELSORB Process, 559... 

To avoid the cost and disposal problems of once-through processes employing alkali metal compounds, a considerable amount of research and development effort has been expended on techniques for regenerating this type of absorbent. Processes used employ precipitation of insoluble compounds (double alkali), and thermal decomposition (Wellman-Lord and Elsorb). Processes under development or which have been investigated include precipitation of insoluble compounds (zinc oxide), low-temperature reduction of sulfite (citrate and potassium formate processes), high-temperature reduction (aqueous carbonate process), electro-dialysis (SOXAL), and electrolytic (Stone Webster/Ionics Process). Descriptions of some of these processes are provided in subsequent sections. 

The ELSORB process, offered by Elkem Technology of Norway, is similar to the Wellman-Lord process in that it utilizes an aqueous solution of sodium salts for SO2 absorption. However, the salts are sodium salts of phosphoric acid, which are claimed to buffer the solution, thereby reducing the amount of recirculation and the size of the regeneration equipment. Oxidation of sulfite to sulfate is said to be less than 0.5%-1.0% (with 8-12% O2 in the gas stream). Regeneration by heating and evaporation is similar to the Wellman-Lord process, but there is very little crystal formation, so there are no solids in the circulation loop and no encrustation in the evaporator. The Elsorb regeneration process operates at 120°C and atmospheric pressure. Corrosion problems have not been reported, and 316 stainless steel is used in the absorber and evaporator (Ulset and Erga, 1991 Peterson, 1992). 

Ulset, T., and Erga, O., 1991, The ELSORB Process A New Regenerable FGD Process for Utility Boilers. paper presented at IGCl Forum 91, Washington, D.C. 

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