Process for the purification of carbon dioxide

Claim 1

A PROCESS FOR TREATING CRUDE CARBON DIOXIDE CONTAINING A SMALL AMOUNT OF NON-CONDENSIBLE GAS AND IMPURITIES HAVING BOILING POINTS ABOVE AND BELOW CARBON DIOXIDE AND SUPPLIED AT AN ELEVATED PRESSURE CAPABLE OF LIQUEFYING CARBON DIOXIDE WHEN THE TEMPERATURE IS REDUCED SUFFICIENTLY BELOW THE CONDENSING POINT OF CARBON DOXIDE AT THE PRESSURE USED TO PRODUCE A SUBSTANTIALLY PURE LIQUID CARBON DOXIDE SUBSTANTIALLY FREE FROM SAID IMPURITIES COMPRISING THE STEPS OF SUPPLYING TO A SEPARATOR SAID CRUDE CARBON DIOXIDE UNDER AN ELEVATED PRESSURE CAPABLE OF LIQUEFYING SAID CARBON DIOXIDE WHEN THE TEMPERATURE IS LOWERED BELOW THE CORRESPONDING LIQUEFACTION POINT, REDUCING THE PRESSURE OF THE CRUDE CARBON DIOXIDE ENTERING THE SEPARATOR SUFFICIENTLY TO CONDENSE IMPURITIES HAVING HIGHER BOILING POINTS THAN CARBON DIOXIDE WHEREBY PARTIAL PURIFICATION IS EFFECTED, PASSING THE PARTIALLY PURIFIED CARBON DIOXIDE TO A FRACTIONATOR AND THERE FURTHER REDUCING THE PRESSURE AND LIQUEFYING ADDITIONAL IMPURITIES THEREFROM HAVING HIGHER BOILING POINTS THAN CARBON DIOXIDE, REMOVING THE CONDENSED IMPURITIES FROM THE SEPARATOR AND FRACTIONATOR TO EFFECT FURTHER PURIFICATION OF THE CARBON DIOXIDE, PASSING THE FURTHER PURIFIED CARBON DIOXIDE UNCONDENSED IN THE FRACTIONATING ZONE TO A CONDENSING ZONE, REDUCING ITS TEMPERATURE SUFFICIENTLY TO LIQUEFY CARBON DIOXIDE THEREFROM, PASSING THE LIQUEFIED CARBON DIOXIDE TO A STRIPPING ZONE, AND SEPARATING NON-CONDENSIBLES TO COMPLETE THE PURIFICATION OF THE LIQUEFIED CARBON DIOXIDE AS A MAIN PRODUCT.