US 5,348,592 AGranted

Method of producing nitrogen-hydrogen atmospheres for metals processing

AssigneeAir Products and Chemicals, Inc.

InventorsDiwakar Garg, Brian B. Bonner, Paul T. Kilhefner, Paul A. Mattiola, David L. Mitchell

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Abstract

An improved method for producing substantially moisture- and oxygen-free, nitrogen-hydrogen atmospheres suitable for annealing, hardening, brazing, and sintering ferrous and non-ferrous metals and alloys is disclosed. According to the disclosed method, suitable nitrogen-hydrogen atmosphere is produced by 1) generating a nitrogen stream containing about 0.1 to 5% residual oxygen by a known non-cryogenic air separation technique, 2) mixing it with a pre-determined but more than stoichiometric amount of hydrogen required to convert residual oxygen to moisture, 3) converting residual oxygen to moisture by reaction with hydrogen in a catalytic reactor, 4) cooling the reactor effluent stream, and 5) removing moisture from it in a regenerative sorbent dryer.

Claims7

Dependent claims

A process of generating a gas mixture having a fixed amount of hydrogen mixed with nitrogen for injecting into a single heat treating furnace or multiple heat treating furnaces comprising the steps of:

mixing non-cryogenically produced nitrogen gas containing up to five percent by volume oxygen with hydrogen, said hydrogen being present in an amount equal to that required to convert residual oxygen in the nitrogen to moisture plus an amount to result in more than 0.1 percent by volume hydrogen in the final gas mixture;
passing said non-cryogenically produced nitrogen and hydrogen through a catalytic reactor for conversion of said oxygen to moisture resulting in a mixture of nitrogen, hydrogen and moisture;
removing moisture from said mixture of nitrogen, hydrogen and moisture by passing said mixture of nitrogen, hydrogen and moisture through a phase separator followed by a regenerative sorbent dryer;
and
injecting said nitrogen-hydrogen mixture into said heat treating furnace.

2 more elements

Dependencies are inferred from the claim text.