Membrane electrodialysis process for recovery of sulfur dioxide from power plant stack gases

Abstract A new regenerative process for recovery of sulfur dioxide from stack gases by sodiumbased solution scrubbing is described. The spent solution from the scrubber, consisting mostly of bisulfite, is converted through the use of a novel low-energy membrane electrodialysis technique to a basic solution of sulfite/hydroxide suitable for reuse in the SO2 absorbers, and a solution of sulfurous acid from which concentrated SO2 is easily regenerated. p]This electrodialysis process, based on bipolar membrane technology, requires only a fraction of the energy required in conventional electrolysis. Engineering estimates indicate that this membrane/SO2 process has a significant economical advantage over other gas desulfurization processes. In addition, this process has internal flexibility to operate under various conditions without the requirement of significant equipment modification.