Continuous vacuum filtration

Claim 1

A METHOD OF SEPARATING HIGH MELTING POINT WAX FROM A WAX CONCENTRATION OBTAINED IN DEWAX ING WAX-BEARING LUBRICATING OIL STOCK, SAID CONCENTRATE COMPRISING A MIXTURE OF HIGH MELTING POINT WAX, LOW MELTING POINT WAX AND A SMALL AMOUNT OF OIL, BY CONTINUOUS FILTRATION IN THE PRESENCE OF SOLVENT LIQUID IN A SERIES OF AT LEAST THREE ROTARY DRUM VACUUM FILTER STAGES AT A TEMPERATURE IN THE RANGE OF 65* F. AND LOWER, EACH FILTER DRUM BEING ABOUT FOUR TO FIVE FEET IN DIAMETER, WHEREIN FILTER CAKE FROM A PRECEDING STAGE IS CHARGED TO A SUCCEEDING STAGE AND FILTRATE FROM A SUCCEEDING STAGE OBTAINED DURING CAKE DEPOSITION IN THAT STAGE IS COMMINGLED WITH CHARGE PASSING TO A PRECEDING STAGE, WHICH COMPRISES ROTATING EACH FILTER DRUM AT A PERIPHERAL SPEED SUBSTANTIALLY IN EXCESS OF 32 FEET PER MINUTE BUT AT A ROTATIONAL SPEED NOT GREATER THAN ABOUT 15 R. P. M., FILTERING IN THE INITIAL STAGE OF SAID SERIES A COMMINGLED MIXTURE OF FRESH CONCENTRATE AND FILTRATE FROM AN INTERMEDIATE STAGE IN THE SERIES TO FORM AN INITIAL FILTRATE SOLVENT AND OIL AND AN INITIAL FILTER CAKE CONTAINING MAINLY WAX AND SOLVENT, DISCHARGING INITIAL FILTRATE, COMMINGLING WITH SAID INITIAL CAKE, PRIOR TO CHARGING TO THE NEXT STAGE IN SERIES, FILTRATE OBTAINED FROM A STAGE SUCCEEDING SAID NEXT STAGE, FILTERING THE RESULTING COMMINGLED MIXTURE CONTAINING INITIAL FILTER CAKE IN SAID NEXT STAGE THEREBY FORMING INTERMEDIATE FILTRTE CONTAINING SOLVENT AND LOW MELTING POINT WAX AND AN INTERMEDIATE FILTER CAKE CONTAINING AN INCREASED CONCENTRATION OF HIGH MELTING POINT WAX, SAID INTERMEDIATE FILTRATE BEING RECYCLED AT LEAST IN PART THE STATE IMMEDIATELY PRECEDING SAID INTERMEDIATE STAGE, COMMINGLING INTERMEDIATE FILTER CAKE WITH FRESH SOLVENT LIQUID, FILTERING THIS LAST MENTIONED COMMINGLED MIXTURE IN THE AFORESAID SUCCEEDING STAGE THEREBY FORMING A FINAL FILTER CAKE CONTAINING PRODUCT WAX AND A FINAL FILTRATE CONTAINING SOLVENT PLUS A SMALL AMOUNT OF LOW MELTING POINT WAX, DISCHARGING THE FINAL FILTER CAKE, RECYCLING FINAL FILTRATE AT LEAST IN PART TO AN INTERMEDIATE STAGE FOR MIXING WITH INTERMEDIATE FILTER FEED, AND MAINTAINING EACH FILTER STAGE AT SUBSTANTIALLY THE SAME TEMPERATURE.

Claim 2

A METHOD OF SEPARATING HIGH MELTING POINT WAX FROM A WAX CONCENTRATION OBTAINED IN DEWAX ING WAX-BEARING LUBRICATING OIL STOCK, SAID CONCENTRATE COMPRISING A MIXTURE OF HIGH MELTING POINT WAX, LOW MELTING POINT WAX AND A SMALL AMOUNT OF OIL, BY CONTINUOUS FILTRATION IN THE PRESENCE OF SOLVENT LIQUID IN A SERIES OF AT LEAST THREE ROTARY DRUM VACUUM FILTER STAGES AT A TEMPERATURE IN THE RANGE OF 65* F. AND LOWER, EACH FILTER DRUM BEING ABOUT FOUR TO FIVE FEET IN DIAMETER, WHEREIN FILTER CAKE FROM A PRECEDING STAGE IS CHARGED TO A SUCCEEDING STAGE AND FILTRATE FROM A SUCCEEDING STAGE OBTAINED DURING CAKE DEPOSITION IN THAT STAGE IS COMMINGLED WITH CHARGE PASSING TO A PRECEDING STAGE, WHICH COMPRISES ROTATING EACH FILTER DRUM AT A PERIPHERAL SPEED SUBSTANTIALLY IN EXCESS OF 32 FEET PER MINUTE BUT AT A ROTATIONAL SPEED NOT GREATER THAN ABOUT 15 R. P. M., FILTERING IN THE INITIAL STAGE OF SAID SERIES A COMMINGLED MIXTURE OF FRESH CONCENTRATE AND FILTRATE FROM AN INTERMEDIATE STAGE IN THE SERIES TO FORM AN INITIAL FILTRATE SOLVENT AND OIL AND AN INITIAL FILTER CAKE CONTAINING MAINLY WAX AND SOLVENT, DISCHARGING INITIAL FILTRATE, COMMINGLING WITH SAID INITIAL CAKE, PRIOR TO CHARGING TO THE NEXT STAGE IN SERIES, FILTRATE OBTAINED FROM A STAGE SUCCEEDING SAID NEXT STAGE, FILTERING THE RESULTING COMMINGLED MIXTURE CONTAINING INITIAL FILTER CAKE IN SAID NEXT STAGE THEREBY FORMING INTERMEDIATE FILTRTE CONTAINING SOLVENT AND LOW MELTING POINT WAX AND AN INTERMEDIATE FILTER CAKE CONTAINING AN INCREASED CONCENTRATION OF HIGH MELTING POINT WAX, SAID INTERMEDIATE FILTRATE BEING RECYCLED AT LEAST IN PART THE STATE IMMEDIATELY PRECEDING SAID INTERMEDIATE STAGE, COMMINGLING INTERMEDIATE FILTER CAKE WITH FRESH SOLVENT LIQUID, FILTERING THIS LAST MENTIONED COMMINGLED MIXTURE IN THE AFORESAID SUCCEEDING STAGE THEREBY FORMING A FINAL FILTER CAKE CONTAINING PRODUCT WAX AND A FINAL FILTRATE CONTAINING SOLVENT PLUS A SMALL AMOUNT OF LOW MELTING POINT WAX, DISCHARGING THE FINAL FILTER CAKE, RECYCLING FINAL FILTRATE AT LEAST IN PART TO AN INTERMEDIATE STAGE FOR MIXING WITH INTERMEDIATE FILTER FEED, AND MAINTAINING EACH FILTER STAGE AT SUBSTANTIALLY THE SAME TEMPERATURE.