Propane fractionation of reduced crude oil

Claim 1

IN THE PROPANE FRACTIONATION OF LUBRICATING OIL CONSTITUENTS FORM LOW ASPHALT-CONTENT REDUCED CRUDE LUBRICATING OIL STOCKS AND THE SIMULTANEOUS PROPANE FRACTIONATION OF SAID LUBRICATING OIL CONSTITUENTS WHEREIN SOLID TO SEMISOLID ASPHALTIC MATERIAL PRECIPITATES UPON INITIAL CONTACT WITH THE PROPANE UNDER LIQUID PROPANE FRCTIONATION CONDITIONS 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 SOLID TO SEMI-SOLID ASPHALTIC MATERIAL AND PLUGGING SAID APPARATUS WITH THE PRECIPITATED ASPHALT COMPRISING MAINTAINING A BODY OF AN OIL-RICH PHASE IN THE LOWER PORTION OF AN ELONGATED AND VERTICALLY DISPOSED CONTACTING ZONE, INTRODUCING LIQUID PROPANE INTO SAID BODY OF OIL-RICH PHASE AT A POINT NEAR THE BOTTOM OF SAID ZONE, MAINTAINING A BODY OF OIL DISSOLVED IN LIQUID PROPANE IN SAID ZONE ABOVE AND IN CONTACT WITH THE FIRST MENTIONED BODY OF OIL-RICH PHASE WITH A LIQUID-LIQUID INTERFACE THEREBETWEEN AT A LEVEL NEAR THE MIDPOINT, VERTIALLY, OF SAID ZONE, INTRODUCING SAID REDUCED CRUDE LUBRICATING OIL STOCK INTO SAID FIRST MENTIONED BODY OF OIL-RICH PHASE AT A POINT BELOW SAID INTERFACE BUT ABOVE THE POINT OF INTRODUCTION OF SAID LIQUID PROPANE, MAINTAINING SUBSTANTIALLY THE SAME CONSTANT TEMPERATURE AT THE OIL FEED POINT AND THROUGHOUT SAID BODY OF OIL-RICH PHASE, MAINTAINING SAID BODY OF OIL DISSOLVED IN LIQUID PROPANE UNDER CONDITIONS CAUSING PROPANE FRACTIONATION OF THE LUBRICATING OIL CONSTITUENTS BY MAINTAINING A TEMPERATURE GRADIENT FROM THE BOTOM TO THE TOP OF SAID BODY OF OIL DISSOLVED IN LIQUID PROPANE BY THE ADDITION OF HEAT TO SAID TOP OF SAID BODY OF OIL DISSOLVED IN LIQUID PROPANE WITH THE BOTTOM BEING SUBSTANTIALLY AT THE TEMPERAURE OF SAID OIL-RICH PHASE AND THE TOP BEING AT A HIGHER TEMPERATURE AND AT A PRESSURE SUFFICIENTLY HIGH TO MAINTAIN THE PROPANE IN THE LIQUID PHASE UNDER THE AFORESAID TEMPERATURE CONDITIONS, REMOVING AN OIL-IN-PROPANE SOLUTION FROM THE UPPER PORTION OF SAID BODY OF OIL DISSOLVED IN LIQUID PROPANE AND REMOVING OIL-RICH PHASE COMPRISING THE ASPHALT, A RESIDUAL LUBRICATING OIL FRACTION AND SOME DISSOLVED PROPANE FROM THE LOWER PORTION OF SAID FIRST MENTIONED BODY OF OIL-RICH PHASE.