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US 2001/0032480 A1Published application
Method and apparatus for producing nitrogen from air by cryogenic distillation
OwnerRobert Anthony Mostelloinventor
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Abstract
Nitrogen gas at a single pressure is produced from a two-column cryogenic distillation of air. The bottoms liquid product from the high pressure column is divided into portions, at least one of which does not enter the low pressure column as a feed stream. By these means, a portion of an oxygen-rich stream is removed from the distillation, further enhancing nitrogen recovery and achieving low specific energy consumption for nitrogen product.
Claims15
A process for the distillation of air consisting of two distillation columns, a high pressure column and a low pressure column, where:
- a. the bottoms liquid product of the high pressure column is divided into a first part which feeds the low pressure column;
- and a second part which serves as coolant for condensing at least one vapor stream from the high pressure column which is returned to the high pressure column as a reflux stream
- b. the vaporization of said coolant takes place serially in at least two coolant vaporization stages each of which condenses vapor
- c. the composition of said coolant becomes richer in its higher boiling components as said coolant vaporizes in subsequent stages
- d. the vaporized coolant from the last stage of vaporization does not re-enter the distillation column process, and
- e. all of said vaporized coolant from the initial stage of vaporization enters the low pressure distillation column
- f. at least one coolant vaporization stage is used to condense nitrogen overhead vapor from the high pressure column.
4 more elements
An apparatus for the production of nitrogen from air comprising:
- a. equipment for compressing and purifying air;
- b. heat exchange means for cooling air and warming products of air separation;
- c. two distillation columns of higher and lower pressure for the separation of air by cryogenic distillation;
- d. at least two condensers are employed for condensing vapors at higher pressure column pressure in which a coolant is vaporized, becoming richer in its higher boiling components, condensing at least nitrogen overhead vapor;
- e. means for returning condensed nitrogen vapor to higher pressure column as reflux;
- f. means for withdrawing nitrogen vapor from the higher pressure column as nitrogen product of the plant
- g. means for transferring condensed additional streams, such as air, to higher pressure column, lower pressure column, or both
- h. means for transference of part of a bottom liquid product of the high pressure column to the at least two condensers employed for condensing vapors;
- i. means for transference of part of a bottom liquid product of the higher pressure column to the lower pressure column;
- j. means for turboexpansion of vapor derived from one or more condensers of the higher pressure column, if desired;
- k. means of supplying supplementary or total refrigeration to the process by addition of a liquid cryogen, if desired;
- l. means for transference of the liquid bottoms product of the lower pressure column to the condenser of the lower pressure column to effect condensation of the overhead nitrogen vapor of the lower pressure column;
- m. means for pumping part of the condensed overhead vapor from the lower pressure column to sufficient pressure and then for injecting said part into the higher pressure column;
- n. means for returning part of condensed overhead vapor from low pressure column back to the low pressure column as reflux.
11 more elements
Dependencies are inferred from the claim text.