Production Of High-Pressure Gaseous Nitrogen

Abstract

The present invention is an improved process for producing elevated pressure nitrogen. This method includes providing an air separation unit with at least two columns, an LP column and an MP column, and cooling a compressed feed air stream in a heat exchanger, then expanding the resulting cooled feed air stream in an expander, thereby producing a quantity of work and a cooled inlet air stream, feeding the cooled inlet air stream into the LP column. Then extracting a nitrogen stream from the MP column, and warming a first portion of the nitrogen stream in the heat exchanger, thereby producing a product nitrogen stream. Then compressing a second portion of the nitrogen stream in a compressor, thereby producing medium pressure nitrogen stream, and introducing the medium pressure nitrogen stream into an LP column vaporizer. Then extracting a second nitrogen stream from the LP column, and cooling the second nitrogen stream in a condenser thereby producing a liquid nitrogen stream. Then introducing a first portion of the liquid nitrogen stream into the LP column, increasing the pressure of a second portion of the liquid nitrogen stream, thereby producing a pressurized liquid nitrogen stream, and introducing a first portion of the pressurized liquid nitrogen stream into the MP column, and export a second portion of the pressurized liquid nitrogen stream as product.

1 . An improved process for producing elevated pressure nitrogen, comprising;
 providing an air separation unit with at least two columns, a LP column ( 101 ) and an MP column ( 102 ),   cooling a compressed feed air stream ( 103 ) in a heat exchanger ( 106 ), then expanding the resulting cooled feed air stream ( 107 ) in an expander ( 139 ), thereby producing a quantity of work and a cooled inlet air stream ( 140 ), feeding said cooled inlet air stream into said LP column,   extracting a nitrogen stream ( 133 ) from said MP column,   warming a first portion ( 119 ) of said nitrogen stream in said heat exchanger, thereby producing a product nitrogen stream ( 135 ),   compressing a second portion ( 120 ) of said nitrogen stream in a compressor ( 123 ), thereby producing medium pressure nitrogen stream ( 124 ),   introducing said medium pressure nitrogen stream into an LP column vaporizer,   extracting a second nitrogen stream ( 125 ) from said LP column,   cooling said second nitrogen stream in a condenser ( 113 ) thereby producing a liquid nitrogen stream ( 126 ),   introducing a first portion ( 127 ) of said liquid nitrogen stream into said LP column,   increasing the pressure of a second portion ( 128 ) of said liquid nitrogen stream, thereby producing a pressurized liquid nitrogen stream ( 129 ), and   introducing a first portion ( 130 ) of said pressurized liquid nitrogen stream into said MP column, and export a second portion ( 131 ) of said pressurized liquid nitrogen stream as product.   
     
     
         2 . The process of  claim 1 , wherein said product nitrogen stream is further compressed in a product compressor ( 136 ), thereby producing a pressurized product nitrogen stream ( 137 ). 
     
     
         3 . The process of  claim 1 , further comprising;
 removing a vapor stream ( 116 ) from said condenser ( 113 ),   removing a rich liquid stream ( 110 ) from said MP column ( 102 ).   providing a second auxiliary heat exchanger ( 111 ),   Introducing said vapor stream and said rich liquid stream into said second auxiliary heat exchanger, thereby producing a cold rich liquid stream ( 112 ) and a warmed stream ( 117 ).