REDESIGN OF AMMONIA ABSORPTION REFRIGERATION UNITS FOR LOW TEMPERATURE APPLICATIONS IN NATURAL GAS PROCESSING

GAS TRANSMISSION PIPELINES REQUIRE NATURAL GAS DELIVERED TO THEM TO MEET A HYDROCARBON (HC) DEWPOINT SPECIFICATION IN ORDER THAT THE HC LIQUIDS ARE NOT DROPPED OUT IN THE LINE DURING TRANSMISSION. SIMILAR SPECIFICATIONS ARE IMPOSED BY PLANT OPERATORS ON THE FUEL GAS THAT IS CONSUMED BY THEIR MACHINERY. A MARKET EXISTS FOR AN ECONOMICAL AMMONIA (NH3) ABSORPTION UNIT TO REPLACE COMPRESSION UNITS UTILIZING FREON THAT WILL PRODUCE REFRIGERATION AT TEMPERATURES IN THE RANGE OF -10 DEGREES TO -15 DEGREES FAHRENHEIT. EXISTING COMMERCIALLY AVAILABLE AIR COOLED NH3 ABSORPTION REFRIGERATION UNITS ARE DESIGNED AND MANUFACTURED TO PRODUCE REFRIGERATION IN THE 40 TO 44 DEGREES FAHRENHEIT RANGE WITH AMBIENT AIR TEMPERATURES RANGING FROM 20 TO 100 DEGREES FAHRENHEIT. THE NH3 UNITS ARE SEALED UNITS UTILIZING SIMPLE LOW COST MECHANICAL DEVICES TO REGULATE THE PROCESS FLOW. TO EXTEND THE TEMPERATURE RANGE DOWN TO -15 DEGREES FAHRENHEIT UTILIZING SIMPLE LOW COST CONTROLS WILL REQUIRE SOME INNOVATIVE CONTROL TECHNOLOGY, COMPONENT MODIFICATION, AND TEST UNDER VARYING LOAD AND AMBIENT CONDITIONS. A TEST UNIT NOW OPERATES AT 20 DEGREES FAHRENHEIT. THE NEXT STEP WILL REQUIRE DIFFERENT CONTROLS AND REDESIGN OF THE UNIT COMPONENTS TO ACHIEVE THE LOWER TEMPERATURES. THE OBJECTIVE OF PHASE I IS TO BUILD TESTING FACILITIES, PROVIDE A SOPHISTICATED VARIABLE CONTROL AND MONITORING SYSTEM, DO A DETAILED EVALUATION OF THE COMPONENTS IN THE UNIT, AND DO A PRELIMINARY EVALUATION OF A NEW, LOW COST CONTROL SYSTEM.