Abstract: The present invention employs a dry-type condenser capable of heat exchange even at small temperature difference for the condensers for the crude argon column, deoxidation column, and pure argon column in an argon separation apparatus using air liquefication and distillation. Additionally, oxygen-enriched liquefied air withdrawn from a plate which is higher than the bottom of the higher pressure column of a double distillation column is employed as the cold source for the condensers. As a result, a large temperature difference between the condensive and vaporative sides of each column's condensers can be obtained. Moreover, even when the total number of theoretical steps of the crude argon column and the deoxidation column exceeds 100, it is not necessary to provide a blower to increase pressure of the crude argon. Thus, the cost of the apparatus and its operation can be reduced.

Abstract: A condenser-evaporator is constituted in such a way that first fluid chambers and second fluid chambers are alternately formed by multiple vertical partitions and a liquid in the first fluid chambers exchange heat with a fluid in the second fluid chambers, characterized in that a plurality of heat exchanger plates are arranged in multiple stages in the first fluid chambers to form a liquid passage having one end open, a plurality of liquid reservoirs communicating with the liquid passage and having a top open are provided in multiple stages on a side of the other end of the liquid passage, and a liquid is introduced in the liquid passage for heat exchange while being supplied to the liquid reservoir in each stage. Accordingly, the depth of the liquid is shallow so as to prevent a boiling point elevation due to the liquid head pressure, thus improving the efficiency of the condenser-evaporator.