Process for purifying gases

Claim 1

A PROCESS FOR COOLING AND CLEANING AN IMPURITY-CONTAINING GAS COMPRISING THE STEPS OF PROVIDING A FIRST HEAT EXCHANGE ZONE HAVING FIRST AND SECOND THERMALLY ASSOCIATED PASSAGEWAYS AND A SECOND HEAT EXCHANGE ZONE HAVING THIRD AND FOURTH THERMALLY ASSOCIATED PASSAGEWAYS; PROVIDING AN IMPURITY-CONTAINING FEED GAS AT THE LOWER END OF SAID FIRST PASSAGEWAY FOR UPWARD FLOW THERETHROUGH TO THE TOP END OF SUCH PASSAGEWAY; PROVIDING A FIRST REFRIGERANT FLUID FOR FLOW THROUGH SAID SECOND PASSAGEWAY; COOLING SAID IMPURITY-CONTAINING FEED GAS BY HEAT EXCHANGE WITH SAID FIRST REFRIGERANT DURING SAID UPWARD FLOW TO A TEMPERATURE BETWEEN THE LIQUEFACTION AND SNOW POINTS OF SAID IMPURITY THEREBY CONDENSING THE IMPURITY AS A LIQUID ON THE WALLS OF SAID FIRST PASSAGEWAY; DRAINING THE CONDENSED IMPURITY FROM THE PASSAGEWAY LOWER END; DISCHARGING THE IMPURITY-DEPLETED FEED GAS FROM SAID TOP END OF SAID FIRST PASSAGEWAY AND DIRECTING THE GAS TO THE LOWER END OF SAID THIRD PASSAGEWAY FOR UPWARD FLOW THERETHROUGH TO THE TOP END OF SUCH PASSAGEWAY; PROVIDING A SECOND REFRIGERANT FLUID FOR FLOW THROUGH SAID FOURTH PASSAGEWAY IN SAID SECOND HEAT EXCHANGE ZONE; FURTHER COOLING SAID IMPURITY-DEPLETED FEED GAS BY HEAT EXCHANGE WITH SAID SECOND REFRIGERANT DURING SAID UPWARD FLOW TO A TEMPERATURE BELOW THE SNOW POINT OF SAID IMPURITY THEREBY DEPOSITING THE FROZEN IMPURITY ON THE WALLS OF SAID THIRD PASSAGEWAY; DISCHARGING AN IMPURITY-FURTHER DEPLETED PRODUCT GAS FROM THE TOP END OF SAID THIRD PASSAGEWAY; TERMINATING THE FLOW OF SAID IMPURITY-DEPLETED FEED GAS TO SID THIRD PASSAGEWAY AND THE FLOW OF SAID SECOND REFRIGERANT TO SAID FOURTH PASSAGEWAY; WARMING SAID THIRD PASSAGEWAY SUFFICIENTLY TO MELT SAID FROZEN IMPURITY; DRAINING THE MELTED IMPURITY FROM THE THIRD PASSAGEWAY LOWER END AND FLOWING SUCH LIQUID IMPURITY IN HEAT EXCHANGE RELATION WITH SAID IMPURITY-CONTAINING FEED GAS IN SAID FIRST PASSAGEWAY THEREBY EFFECTING COOLING OF SUCH FEED GAS AND EVAPORATION OF THE IMPURITY.