| 摘要 |
An air separation method for producing a gaseous oxygen product at a delivery pressure comprising (a) forming a compressed and purified air stream and dividing the stream into first (22) and second (24) subsidiary streams. (b) cooling the first subsidiary stream in heat exchanger (28) to a temp suitable for rectification by cryogenic distillation. (c) cooling the second subsidiary stream in heat exchanger (28) to an intermediate temp above the temp suitable for rectification of the first subsidiary stream. (d) introducing the first subsidiary stream into an air separation unit (30) having higher (32) and lower (34) pressure columns connected to one another in a heat transfer relationship by condenser/reboiler (36) so that liquid oxygen is produced as a column bottom of the lower pressure column. (e) pumping the liquid oxygen stream (58) to the delivery pressure by pump (60). (f) expanding the second subsidiary stream with the performance of work to form a gaseous refrigerant stream (68) at the delivery pressure. (g) introducing the pumped liquid oxygen stream into the top region (74) of a mixing column (70) and the gaseous refrigerant stream into the column bottom region (72). (h) withdrawing a liquid refrigerant stream (80) form the mixing column bottom region and introducing the stream into the low pressure column. (i) forming the gaseous oxygen product by removing a product stream (76) from the mixing column top. The introduction of the liquid refrigerant stream will increase the liquid to vapour ratio in the low pressure column to in turn increase liquid oxygen production of the gaseous oxygen product over potential production had the gaseous refrigerant stream been directly introduced into the low pressure column. Also claimed is an air separation appts (10) including a filter (14), a main compressor (16), an after-cooling (18) and a prepurification unit (20) to compress and purify an incoming air stream (12) and a method in which a medium pressure nitrogen stream (50) removed from the high pressure column is compressed to a nitrogen delivery pressure. |
