Apparatus and process for 4-step separation of a crystallizable component of a mixed feedstock

Abstract

Abstract THIS INVENTION IS A 4-STEP SEPARATION PORCESS. A FEEDSTOCK IS PARTIALLY FROZEN, (1) THE RESULTING CRYSTALS ARE SEPARATED FROM THE REMAINING LIQUID, THE CRYSTALS ARE PURIFIED BY COUNTERCURRENT CONTACT WITH SOM OF THE MELT OBTAINED BY MELTING THE PURIFIED CRYSTALS, (2) THE REMAINING MELT IS SEPARATED AS PRODUCT, THE MOTHER LIQUOR FROM THE PURIFICATION IS PARTIALLY FROZEN, (3) THE RESULTING CRYSTALS ARE SEPARATED FROM THE REMAINING LIQUID, THE CRYSTALS ARE PURFIED AS IN (1), AND (4) THE REMAINING MELT IS SEPARATED AS PRODUCT. THIS SAVES REFRIGERATION OVER THE PRIOR ART. A MORE COMPLETE ABSTRACT IS GIVEN IN THE NEXT TWO PARAGRAPHS. A FIRST FEEDSTOCK CONTAINING A MIXTURE OF COMPONENTS IS COOLED IN A FIRST COOLING STEP TO AT LEAST PARTIALLY CRYSTALLIZE AT LEAST ONE OF SAID COMPONENTS FROM SOLUTION TO FORM A FIRST SLURRY OF CRYSTALS IN A FIRST NONCRYSTALLIZED MOTHER LIQUOR. IN A FIRST SEPARATION STEP FIRST CRYSTALS ARE SEPARATED FROM SAID FIRST MOTHER LIQUOR. SAID FIRST CRYSTALS FROM SAID FIRST SEPARATION STEP ARE SLURRIED WITH A SECOND MOTHER LIQUOR TO FORM A SECOND SLURRY, COOLED IN A SECOND COOLING STEP AND PASSED INTO A FIRST CRYSTALS PURIFICATION ZONE INTO CONTACT WITH A FIRST HEATING ELEMENT AT THE END OF SAID ZONE. SOME OF THE RESULTING FIRST MELT FROM THE END OF SAID ZONE IS TAKEN OFF IN A SECOND SEPARATION STEP AS THE SEPARATED FIRST COMPONENT PRODUCT, WHILE SOME OF SAID FIRST MELT IS PASSED IN COUNTERCURRENT CONTACT WITH SAID FIRST CRYSTALS WHEREIN IT IS REFROZEN AND RETURNED TO THE MELT ZONE. THE REFREEZING ACTION DISPLACES OCCLUDED MOTHER LIQUID FROM THE CRYSTALS, WHICH IS REMOVED IN A FILTER ZONE UPSTREAM OF SAID MELT ZONE AS SAID SECOND MOTHER LIQUOR. SOME OF SAID SECOND MOTHER LIQUOR IS MIXED WITH A THIRD MOTHER LIQUOR AND COOLED IN A THIRD COOLING STEP TO FORM A THIRD SLURRY OF SECOND CRYSTALS OF SAID FIRST COMPONENT IN A FOURTH MOTHER LIQUOR. IN A THIRD SEPARATION STEP SAID SECOND CRYSTALS ARE SEPARATED FROM SAID FOURTH MOTHER LIQUOR. SAID SECOND CRYSTALS FROM SAID THIRD SEPARATION STEP ARE SLURRIED WITH SOME OF SAID SECOND MOTHER LIQUOR TO FORM A FOURTH SLURRY AND PASSED INTO A SECOND CRYSTALS PURIFICATION ZONE INTO CONTACT WITH A SECOND HEATING ELEMENT AT THE END OF SAID SECOND ZONE. THE RESULTING SECOND MELT FROM THE END OF SAID SECOND ZONE IS TAKEN OFF IN A FOURTH SEPARATION STEP AS MORE OF THE SEPARATED FIRST COMPONENT PRODUCT, WHILE SOME OF SAID SECOND MELT IS PASSED BACK IN COUNTERCURRENT CONTACT WITH SAID SECOND CRYSTALS SO AS TO PURIFY SAID SECOND CRYSTAL OF OCCLUDED MOTHER LIQUOR WHICH IS REMOVED FROM SAID SECOND ZONE AHEAD OF SAID SECOND HEATING ELEMENT AS SAID THIRD MOTHER LIQUOR AND PASSED WITH SOME OF SAID SECOND MOTHER LIQUOR TO SAID THIRD COOLING ZONE AS DESCRIBED ABOVE. SAID FIRST AND FOURTH MOTHER LIQUORS ARE HEAT EXCHANGED WITH SAID FIRST FEEDSTOCK PRIOR TO SAID FIRST COOLING STEP IN ORDER TO SAVE REFRIGERATION. BY NOT RECYCLING THE FIRST AND FOURTH MOTHER LIQUORS FROM THE FIRST AND THIRD SEPARATION STEPS, AND BY NOT RECYCLING THE SECOND AND THIRD MOTHER LIQUORS TO THE FEEDSTOCK PRIOR TO SAID FIRST COOLING AND FIRST SEPARATION STEP, AND BY HEAT EXCHANGING SAID FIRST AND FOURTH MOTHER LIQUORS WITH SAID FEEDSTOCK PRIOR TO SAID FIRST COOLING STEP, IN EXAMPLE 1 A SAVINGS OF 429,000 B.T.U./HOUR IN REFRIGERATION IS ACHIEVED OVER THE PRIOR ART OF EXAMPLE 2.

Inventors

• 👤 Robert A Hinton

Bibliographic Details