Condenser-evaporator for large air separation plant

A condenser-evaporator for use in a large air separation plant in which the condenser-evaporator is provided between an upper column and a lower column, the condenser-evaporator condensing nitrogen gas, ascending from the lower column through first conduit means, by heat exchange with liquid oxygen flowing down from an upper column through second conduit means, the improvement which comprises:

• (a) a plurality of vertical evaporator blocks each having upper and lower ends and lateral edges and including first corrugated fins for forming nitrogen passages as nitrogen chambers, second corrugated fins for forming oxygen passages as oxygen chambers, the first fins and the second fins being each alternatively laminated through a separating plate to vertically form the nitrogen passages each opening at the upper and the lower ends of the condenser block and to form the oxygen passages each opening at the lateral edges of the condenser block, the oxygen chambers of each condenser block being divided into vertically disposed multistage groups;
• (b) a first header provided to the upper end of each condenser block, the first header being connected to the first conduit means for introducing nitrogen gas from the lower column into the nitrogen chambers of the condenser blocks;
• (c) a second header provided to the lower end of each condenser block;
• (d) a third conduit means, connected to each second header, for extracting nitrogen condensed in the nitrogen chambers of the condenser blocks;
• (e) means for forming vertically disposed multistage compartments for holding liquid oxygen including a lowermost stage compartment, the compartments forming means including a head portion of the lower column for forming the lowermost compartment;
• (f) overflowing means, provided to each compartment disposed above the lowermost compartment, for overflowing liquid oxygen supplied from the upper column substantially at a level to immerse each group of the oxygen chambers in the liquid oxygen;
• (g) fourth conduit means, communicated to the overflowing means, for introducing the liquid oxygen overflowing from one compartment into another lower compartment disposed just below the one compartment;
• and
• (h) oxygen gas ascending means, communicated to each compartment, for ascending and introducing into the upper column oxygen gas produced in each compartment by heat exchange with nitrogen gas.