A SIMPLE THERMAL PUMP FOR IN-THE-FIELD SUPERCRITICAL-FLUID EXTRACTION

A simple heat driven pump for in-the-field supercritical fluid extract ion was constructed and evaluated. The pump pressurized CO2 from a sta ndard (54 atm) siphon tube supply cylinder to over 400 atm. Pressuriza tion was achieved and maintained by cyclic heating of a pump chamber c ontaining CO2 to 250 degrees C then cooling and refilling the pump cha mber with CO2. The pressurized CO2 was transferred to a heated reservo ir from which the CO2 flowed into the extraction cell. Pulse free pres sure was maintained in the extraction cell indefinitely at 135 atm wit h a back pressure regulator. The pressure variation of the solvent del ivered to the extraction cell during this period was negligible. The t otal weight of the system was 5.5 Kg.