Method and apparatus for separating air to produce an oxygen product
AssigneeThe BOC Group, Inc.
InventorsPaul Higginbotham, Joseph P. Naumovitz
Life of this patent
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Abstract
A method and apparatus of separating air to produce an oxygen product. In accordance with the method and apparatus the air is rectified within a double column arrangement. The lower pressure column has lower and intermediate reboilers. Nitrogen from the higher pressure column is compressed and sent to the lower reboiler and oxygen tower overhead from the higher pressure column is fed to the intermediate reboiler. The resultant liquid is used to reflux both columns. The advantages in the arrangement set forth above is that the higher pressure column may be made to operate at a lower pressure to conserve energy.
Claims7
A method of separating air to produce an oxygen product, said method comprising:
- cooling compressed and purified air to a temperature suitable for its rectification and introducing said air into a double column rectification system having a higher pressure column and a lower pressure column;
- rectifying said compressed and purified air within said double column rectification system so that a nitrogen-rich tower overhead and an oxygen-rich liquid column bottoms are produced within said higher pressure column and an oxygen liquid column bottoms is produced within said lower pressure column;
- reboiling said lower pressure column by cold compressing a first nitrogen stream composed of said nitrogen-rich tower overhead and introducing said first nitrogen stream into a reboiler associated with a bottom region of said lower pressure column, thereby to form a nitrogen liquid stream;
- reboiling said lower pressure column at an intermediate location thereof with a second nitrogen rich stream composed of said nitrogen-rich tower overhead, thereby to form an additional nitrogen liquid stream;
- refluxing said lower and higher pressure columns with liquid nitrogen contained within said nitrogen liquid stream and said additional nitrogen liquid stream;
- and
- extracting a product stream composed of said oxygen liquid column bottoms and fully warming said stream through indirect heat exchange with said compressed and purified air, thereby to form said oxygen product.
An apparatus for separating air to produce an oxygen product, said apparatus comprising:
- a main heat exchanger for cooling compressed and purified air to a temperature suitable for its rectification
- a double rectification column system having a higher and lower pressure column configured to rectify said air so that a nitrogen-rich tower overhead and an oxygen-rich liquid column bottoms are produced within said higher pressure column and an oxygen liquid column bottoms is produced within said lower pressure column;
- said main heat exchanger connected to said double rectification column system so that said compressed and purified air is introduced therein;
- a lower reboiler associated with a bottom region of said lower pressure column;
- a cold compressor interposed between said lower reboiler and said higher pressure column to compress a first nitrogen stream composed of said nitrogen-rich tower overhead and introduce said first nitrogen stream into said lower reboiler to form a nitrogen liquid stream;
- an intermediate reboiler associated with an intermediate region of said lower pressure column and connected to said higher pressure column so that a second nitrogen rich stream composed of said nitrogen-rich tower overhead condenses therein and forms an additional nitrogen liquid stream;
- said lower and intermediate reboilers, and said higher and lower pressure columns associated with one another so that liquid nitrogen contained within said nitrogen liquid
- stream and said additional nitrogen liquid stream reflux said higher and said lower pressure columns;
- and
- said lower pressure column connected to said main heat exchanger so that a product stream composed of said oxygen liquid column bottoms is fully warmed through indirect heat exchange with said cooled and compressed air, thereby to form said oxygen product.
Dependencies are inferred from the claim text.