Propane fractionation of lubricating oil stocks

Claim 1

IN THE PROPANE FRACTIONATION OF LUBRICATING OIL CONSTITUENTS FROM LOW ASPHALT-CONTENT REDUCED CRUDE LUBRICATING OIL STOCKS WITH LIQUID PROPANE WHEREIN SOLID ASPHALTIC MATERIAL PRECIPITATES UPON INITIAL CONTACT WITH THE PROPANE AND ADHERES TO AND PLUGS THE FRACTIONATING APPARATUS IN THE REGION ADJACENT AND BELOW THE RAW FEED ENTRY POINT, A PROCESS FOR CONTINUOUSLY CARRYING OUT THIS FRACTIONATION OPERATION WITHOUT PRECIPITATING SAID ASPHALT AND PLUGGING SAID APPARATUS COMPRISING MAINTAINING A MOVING BED OF PARTICULATE MATERIAL IN A FIRST ZONE, SAID PARTICULATE MATTER BEING WITHIN THE SIZE RANGE OF 1/4 INCH TO 1 INCH IN DIAMETER, MAINTAINING A BODY OF LIQUID PROPANE CONTAINING DISSOLVED OIL IN SAID ZONE, MAINTAINING A BODY OF AN OIL-RICH PHASE BELOW SAID BODY OF PROPANE CONTAINING DISSOLVED OIL IN SAID ZONE, SAID BODIES MEETING AT A COMMON INTERFACE, INTRODUCING A STREAM OF LIQUID PROPANE INTO SAID BODY OF PROPANE CONTAINING DISSOLVED OIL AT A POINT NEAR SAID COMMON INTERFACE, INTRODUCING STREAM OF SAID LOW ASPHALT-CONTENT REDUCED CRUDE LUBRICATING OIL STOCK INTO SAID BODY OF PROPANE CONTAINING DISSOLVED OIL AT A POINT ABOVE SAID POINT OF INTRODUCTION OF PROPANE, MAINTAINING THE TOP OF SAID BODY OF PROPANE CONTAINING DISSOLVED OIL AT A HIGHER TEMPERATURE THAN THAT OF THE OIL-RICH PHASE, REMOVING PROPANE CONTAINING DISSOLVED OIL FROM AND RECOVERING THE OIL THEREFROM, REMOVING THE OIL-RICH PHASE FROM THE BOTTOM OF SAID ZONE AND REMOVING PARTICULATE MATERIAL CONTAINING ADHERING ASPHALT FROM THE BOTTOM OF SAID ZONE.