Liquefaction and purification of low temperature gases

Claim 1

IN A SYSTEM FOR LIQUEFYING A GAS HAVING A CRITICAL TEMPERATURE BELOW ABOUT 35 DEGREES KELVIN, SAID SYSTEM OPERATING THROUGH A CYCLE AND RECYCLE IN WHICH THE GAS INCLUDING A FEED-STREAM AND A RECYCLED STREAM IS COMPRESSED AND A PORTION OF SAID RECYCLED STREAM COOLED AND CONVERTED TO THE LIQUID PHASE IN A THROTTLE-VALVE, AND THE REMAINDER OF SAID RECYCLED STREAM RETURNED FOR RECOMPRESSION AND RECYCLING IN SAID SYSTEM, THE METHOD OF REMOVING FROM THE LOW-TEMPERATURE STAGES OF SAID SYSTEM INCLUDING SAID THROTTLE-VALVE SMALL AMOUNTS OF IMPURITIES WHICH KSOLIDIFY IN THE MIXTURE OF SAID GAS BELOW THE TEMPERATURE RANGE OF LIQUID NITROGEN BUT ABOVE THE LIQUEFACTION TEMPERATURE OF SAID GAS, WHICH COMPRISES THE STEPS OF COOLING THE HIGH PRESSURE FEED-STREAM OF SAID GAS INCLUDING SAID IMPURITIES SEPARATELY FROM THE HIGH-PRESSURE RECYCLED GAS TO A TEMPERATURE SLIGHTLY IN EXCESS OF THE FREEZING TEMPERATURE OF SAID IMPURITIES, DIVERTING THE ENTIRE COMPRESSED FEED-STREAM INTO A PATH WHICH AVOIDS SAID THROTTLEVALVE, EXPANDING SAID DIVERTED FEED-STREAM IN AN EXPANSION DEVICE WITH THE PERFORMANCE OF EXTERNAL WORK THEREBY CAUSING SAID IMPURITIES TO FREEZE OUT OF SAID FEED-STREAM IN A FINE SUSPENSION AT A TEMPERATURE-PRESSURE POINT ABOVE THE LIQUEFACTION POINT OF SAID GAS, AND THEREAFTER PASSING SAID EXPANDED FEED-STREAM INCLUDING SAID FROZEN-OUT PURITIES IN SUSPENSION INTO THE LIQUID PHASE FORMED IN SAID SYSTEM, WHEREBY THE PURIFIED GAS BUBBLES THROUTH SAID LIQUID AND RETURNS THROUGH A PATH WHEREBY IT COOLS SAID COMPRESSED GAS IN SAID SYSTEM AND IS SUBSEQUENTLY COMPRESSED AS SAID RECYCLED STREAM, AND PERMITTINGS SAID IMPURITY PARTICLES TO BE ENTRAINED IN SAID LIQUID.