AN ADVANCED LIQUID MEMBRANE SYSTEM FOR NATURAL GAS PURIFICATION

NATURAL GAS IS USUALLY PROCESSED AT THE WELLHEAD TO MAKE IT SUITABLE FOR TRANSPORT IN THE DOMESTIC GAS PIPELINE SYSTEM. IMPURITIES SUCH AS HYDROGEN SULFIDE (H2S), CARBON DIOXIDE (CO2), NITROGEN (N2), AND VARIOUS LIQUIDS MUST BE REMOVED IN A COST-EFFECTIVE MANNER. THE SIMPLICITY AND LOW ENERGY CONSUMPTION OF MEMBRANE DEVICES MAKE THEM VERY ATTRACTIVE FOR SEPARATING SUCH CONTAMINANTS FROM LOW QUALITY NATURAL GAS. AN IDEAL MEMBRANE CAN SELECTIVELY PASS ONE COMPONENT OF A MIXTURE WHILE RETAINING THE OTHERS IN A CONTINUOUS STEADY-STATE PROCESS. HOWEVER, THE MEMBRANE SYSTEM MUST ADDRESS A NUMBER OF PRACTICAL CONSIDERATIONS TO COMPETE WITH OTHER SEPARATION METHODS. A NOVEL MOVING LIQUID MEMBRANE SYSTEM (MLMS) HAS BEEN CONCEIVED FOR THE SELECTIVE REMOVAL OF H2S FROM NATURAL GAS. THE LIQUID MEMBRANE SYSTEM COMBINES ABSORPTION AND REGENERATION INTO A SINGLE UNIT, THEREBY RESULTING IN A SMALLER PROCESSING SYSTEM. THE MLMS IS INTENDED TO PURIFY LOW QUALITY NATURAL GASES WITH H2S CONCENTRATIONS IN THE PERCENT RANGE. THE SYSTEM WILL ACHIEVE THE PIPELINE SPECIFICATION FOR H2S WHILE ATTAINING VERY HIGH SELECTIVITY OF H2S FOR THE CLAUS PLANT. PHASE I CHARACTERIZES THE EFFECT OF MEMBRANE CONFIGURATION AND OPERATING PARAMETERS ON GAS SEPARATION. A PRIMARY OBJECTIVE IS DETERMINATION OF H2S REMOVAL AND SELECTIVITY OF A GAS MIXTURE CONTAINING METHANE, CO2, N2, AND H2S IN A BENCH-SCALE TEST LOOP. IN PHASE II, A PROTOTYPE SYSTEM WILL BE CONSTRUCTED TO EVALUATE THE LONG-TERM OPERABILITY OF THE SYSTEM.