Integrated process for producing atmospheres suitable for heat treating

Abstract

An integrated two-step process for producing low-cost atmospheres suitable for annealing ferrous and non-ferrous metals and alloys, brazing metals, sealing glass to metals, and sintering metal and ceramic powders in continuous furnaces from non-cryogenically produced nitrogen containing up to 3% residual oxygen is disclosed. The residual oxygen present in non-cryogenically produced nitrogen is converted to moisture by mixing it hydrogen and passing the mixture through a reactor packed with a platinum group catalyst in the first step of the process. The reactor effluent stream containing a mixture of nitrogen, unreacted hydrogen, and moisture is mixed with a predetermined amount of a hydrocarbon gas and introduced into the heating zone of a continuous furnace in the second step of the process to 1) convert moisture to a mixture of carbon monoxide and hydrogen by reaction with the hydrocarbon gas via water gas shift reaction and 2) produce atmospheres in-situ suitable for heat treating. The key features of the process include 1) use of economical amount of hydrogen to convert residual oxygen to moisture in an external catalytic reactor and 2) conversion of moisture to a mixture of carbon monoxide and hydrogen by reaction with the hydrocarbon gas via water gas shift reaction in the hot zone of a continuous furnace. The disclosed process is particularly suitable for producing low-cost heat treating atmospheres for continuous furnaces operated at 700.degree. C. and above.