Process and apparatus for producing nitrogen

DETAILED DESCRIPTION We claim: 1.
A process for the production of nitrogen from air, comprising: (a) feeding a gas consisting essentially of air to the cathode of a fuel cell, said fuel cell producing electrical energy, water and an oxygen depleted, nitrogen rich cathode exhaust stream, (b) feeding the oxygen depleted, nitrogen rich cathode exhaust stream to a gas liquefaction apparatus, said liquefaction apparatus producing a mixture of liquid nitrogen and liquid oxygen, (c) feeding the mixture of liquid nitrogen and liquid oxygen to a fractionating apparatus, said fractionating apparatus separating the mixture to produce a stream of nitrogen product and a stream of oxygen byproduct, such process resulting in enhanced energy efficiency in the production of nitrogen.




Description:
DESCRIPTION 1.
Technical Field The field of art to which this invention pertains is the production of nitrogen.
2.
Background Art Purified nitrogen is widely used for such purposes as a feedstock for chemical syntheses or as an inert atmosphere in a variety of processes.
Nitrogen and oxygen are produced from air by liquefaction of the air and fractionation of the liquid air into nitrogen and oxygen product streams.
The process is energy intensive.
There are applications, such as secondary oil recovery, which demand large quantities of nitrogen but in which there is no need for the oxygen byproduct of the liquefaction process.
One approach in such cases is to produce nitrogen and oxygen by air liquefaction, use the nitrogen so produced and simply discard the oxygen byproduct.
Such an approach is inefficient in the sense that resources are expended to produce the oxygen waste product.
Another approach is to use an air stream to oxidize a hydrocarbon fuel in a combustion process to produce a stream of oxygen depleted gas.
The combustion process produces heat and a stream of nitrogen, carbon dioxide and water as well as impurities in the form of sulfur compounds.
The water may be removed by condensation and the carbon dioxide removed by means of a gas scrubber to produce a stream composed chiefly of nitrogen gas