Integrated Reformer and Batch Annealing Processes and Apparatus Therefor

Abstract

Processes and apparatus for batch annealing work pieces in a hydrogen atmosphere use pressure swing sorption to recover hydrogen from the annealing exhaust. In preferred embodiments, hydrogen for the batch annealing is generated by reforming and the recovery of hydrogen is integrated with the reforming operation.

1 . A batch annealing process comprising:
 a. providing in an annealing zone a metal work piece having carbon-containing substance associated therewith which under annealing conditions can cause coke formation;   b. purging free oxygen from the annealing zone containing the metal work piece with an inert gas and withdrawing a pre-annealing purge effluent containing said inert gas and free oxygen;   c. thereafter providing to said annealing zone a hydrogen-containing gas, said gas comprising at least about 50 volume percent hydrogen, said supply being (i) in an amount sufficient to achieve and maintain a hydrogen concentration in said annealing zone and (ii) at a rate, continuous or intermittent, to enhance annealing and provide an off gas containing hydrogen and carbon-containing substance, wherein for at least a portion of time while the hydrogen-containing gas is supplied, said annealing zone is heated to a temperature for a time sufficient to anneal said metal work piece;   d. ceasing providing said hydrogen-containing gas;   e. cooling said annealing zone commencing before or after the cessation of providing said hydrogen-containing gas;   f. purging hydrogen from said annealing zone with an inert gas and withdrawing a post-annealing purge effluent containing said inert gas and hydrogen; and   removing said metal work piece from the annealing zone,   wherein at least a portion of the off gas containing hydrogen of step (c) is subjected to pressure swing sorption on a solid sorbent to provide a hydrogen product containing at least about 50 volume percent hydrogen and is substantially devoid of carbon-containing substance and a reject stream having a lower concentration of hydrogen than the off gas and containing carbon-containing substance.   
   
   
       2 . The process of  claim 1  wherein at least a portion of the hydrogen product is used as hydrogen-containing gas for annealing. 
   
   
       3 . The process of  claim 1  wherein at least a portion of the carbon-containing substance associated with the metal work piece is, under the conditions of step (c) converted to methane and the carbon-containing substance in the off gas of step (c) comprises methane. 
   
   
       4 . The process of  claim 1  wherein at least a portion of the hydrogen-containing gas for step (c) is provided by reforming a hydrocarbon-containing feedstock under reforming conditions. 
   
   
       5 . The process of  claim 4  wherein the reforming conditions comprise elevated temperature and at least a portion of the reject stream is combusted to provide at least a portion of heat to achieve reforming conditions. 
   
   
       6 . The process of  claim 4  wherein the reforming provides a reformate containing hydrogen and at least one of carbon monoxide and carbon dioxide, and the reformate is subjected to pressure swing sorption on a solid sorbent to provide a reformate hydrogen product containing at least about 90 volume percent hydrogen which is substantially devoid of carbon monoxide and carbon dioxide and a reject stream containing hydrogen and at least one of carbon monoxide and carbon dioxide. 
   
   
       7 . The process of  claim 6  wherein the off gas to be subjected to pressure swing sorption is admixed with the reformate and the reformate hydrogen product comprises hydrogen derived from the off gas. 
   
   
       8 . The process of  claim 6  wherein at least a portion of the hydrogen product from the pressure swing sorption of off gas is admixed with the reformate hydrogen product and at least a portion of the reformate hydrogen product is used for annealing. 
   
   
       9 . The process of  claim 8  wherein at least a portion of the reject stream from the pressure swing sorption of the off gas is admixed with the reformate and is subjected to pressure swing sorption with the reformate. 
   
   
       10 . The process of  claim 8  wherein at least a portion of the reject stream from the pressure swing sorption of the reformate is admixed with the off gas and is subjected to pressure swing sorption with the off gas. 
   
   
       11 . The process of  claim 1  wherein the hydrogen-containing gas contains at least about 90 volume percent hydrogen and the annealing zone achieves a hydrogen concentration of at least about 90 volume percent during annealing. 
   
   
       12 . The process of  claim 11  wherein sufficient hydrogen is provided continuously or intermittently during the annealing that the concentration of carbon-containing substances in the off gas is less than about 5 volume percent. 
   
   
       13 . The process of  claim 1  wherein the metal work piece contains oils and at least a portion of the oils are removed from the off gas prior to the off gas being subjected to pressure swing sorption. 
   
   
       14 . The process of  claim 13  wherein the separation of oils is effected by adsorption. 
   
   
       15 . The process of  claim 1  wherein the metal work piece contains oils and at least a portion of the oils are contained in the off gas as the temperature of the annealing zone is increase to annealing temperatures, and the off gas is subjected to pressure swing sorption when the oil content of the off gas is acceptable for pressure swing sorption. 
   
   
       16 . The process of  claim 1  wherein at least a portion of the off gas produced during the annealing is accumulated to provide a constantly available source of off gas for pressure swing sorption that has a more uniform hydrogen concentration. 
   
   
       17 . The process of  claim 1  wherein at least a portion of the hydrogen product is used as hydrogen-containing gas for annealing and at least a portion of the hydrogen product is accumulated to provide a constantly available source of hydrogen product for annealing. 
   
   
       18 . The process of  claim 17  wherein said hydrogen product is accumulated with externally provided hydrogen. 
   
   
       19 . The process of  claim 18  wherein said externally provided hydrogen is from a reformer and at least a portion of the reject stream is used to provide at least a portion of heat to achieve reforming conditions. 
   
   
       20 . The process of  claim 1  wherein at least a portion of the hydrogen product is used as hydrogen-containing gas feed to a fuel cell. 
   
   
       21 . The process of  claim 1  wherein a plurality of annealing zones exist and the off gases from the annealing zones are combined and subjected to pressure swing sorption. 
   
   
       22 . The process of  claim 21  wherein the sequencing of steps (a) to (e) for at least one annealing zone is time shifted from the sequencing of steps (a) to (e) for at least one other annealing zone. 
   
   
       23 . An apparatus for batch annealing comprising:
 a. at least one annealing vessel adapted for annealing a work piece at elevated temperature in the presence of hydrogen, said annealing apparatus having at least one gas inlet and at least one gas outlet;   b. an oil removal system adapted to remove liquid from gas, said system having at least one gas inlet and at least one gas outlet, said inlet being in fluid communication with at least one gas outlet of said annealing vessel; and   c. a pressure swing sorption unit containing sorbent suitable for removing carbon oxides and methane from hydrogen, said unit having at least one gas inlet and at least one gas outlet adapted to provide a reject stream and at least one gas outlet adapted to provide a product stream, said at least one gas inlet being in fluid communication with said at least one gas outlet of the oil removal system.   
   
   
       24 . An apparatus for batch annealing comprising:
 a. at least one annealing vessel adapted for annealing a work piece at elevated temperature in the presence of hydrogen, said annealing apparatus having at least one gas inlet and at least one gas outlet;   b. a reforming unit adapted to reform a hydrocarbon-containing feedstock to produce hydrogen, said unit having at least one outlet;   c. a pressure swing adsorber in fluid communication with at least one outlet of said reforming unit, said pressure swing adsorber containing sorbent suitable for removing carbon oxides and methane from hydrogen, said unit having at least one gas outlet adapted to provide a reject stream and at least one gas outlet adapted to provide a product stream, said at least one gas outlet adapted to provide a product stream being in fluid communication with at lest one gas inlet of said annealing vessel; and   d. a pressure swing adsorber in fluid communication with at least one gas outlet of said annealing vessel, said pressure swing adsorber containing sorbent suitable for removing carbon oxides and methane from hydrogen, said unit having at least one gas outlet adapted to provide a reject stream and at least one gas outlet adapted to provide a product stream, said at least one gas outlet adapted to provide a product stream.   
   
   
       24 . The apparatus of  claim 23  wherein the pressure swing adsorber in fluid communication with at least one outlet of said reforming unit is also the pressure swing adsorber in fluid communication with at last one gas outlet of said annealing vessel. 
   
   
       25 . The apparatus of  claim 23  wherein the pressure swing adsorber in fluid communication with at least one outlet of said reforming unit and the pressure swing adsorber in fluid communication with at least one gas outlet of said anneal vessel are separate; the reforming unit comprises a burner adapted to provide heat for reforming and at least one gas outlet adapted to provide a reject stream of said pressure swing adsorber in fluid communication with at least one gas outlet of said annealing vessel is in fluid communication with the burner.