A NOVEL FLUE GAS TREATMENT PROCESS

SULFUR DIOXIDE (SO2) EMISSIONS FROM THE FLUE GAS OF COAL-FIRED UTILITY POWER PLANTS ARE THE MAJOR CAUSE OF ACID RAIN. TREATMENT OF FLUE GAS BY CONVENTIONAL TECHNOLOGIES IS EXPENSIVE AND PRODUCES LARGE SECONDARY WASTE STREAMS. THIS PROJECT CONCERNS A NEW PROCESS FOR SO2 REMOVAL BASED ON A SCRUBBER/PERVAPORATION HYBRID SYSTEM. THE SYSTEM USES A COMBINATION OF SCRUBBING WITH A REGENERABLE LIQUID, FOLLOWED BY PERVAPORATION USING A HIGHLY SELECTIVE MEMBRANE, TO RECOVER SO2 AS A CONCENTRATE STREAM SUITABLE FOR PRODUCTION OF VALUABLE BYPRODUCTS. BECAUSE OF THE MODULAR NATURE OF MEMBRANE SYSTEMS, THE PROCESS APPEARS TO BE PARTICULARLY SUITABLE TO SMALL COAL-FIRED COMBUSTORS. IN PHASE I, THE OVERALL FEASIBILITY OF THE CONCEPT WILL BE ASSESSED BY SELECTING SUITABLE SO2 SCRUBBING FLUIDS AND THEN REGENERATING THEM BY MEMBRANE PERVAPORATION. HIGHLY SELECTIVE MEMBRANES HAVE ALREADY BEEN DEVELOPED. ON THE BASIS OF THE PROPERTIES OF THESE MEMBRANES, IT SHOULD BE POSSIBLE TO OBTAIN >75% SO2 IN THE FINAL PERVAPORATION CONCENTRATE STREAM, WHILE REMOVING >90% OF THE SO2 CONTAINED IN THE FLUE GAS. THE BASIS OF THESE CALCULATIONS WILL BE CONFIRMED EXPERIMENTALLY AND A PRELIMINARY COST ESTIMATE FOR THE PROCESS PREPARED. IN PHASE II, A BENCH-SCALE SYSTEM WILL BE CONSTRUCTED AND OPERATED IN THE LABORATORY.