Production of hydrogen rich gas

摘要

A process for the production of a hydrogen-rich gaseous mixture comprises contacting a hydrocarbon with steam in a first reforming zone and then contacting the effluent from this zone with steam and a free oxygen containing gas in a second reforming zone, both zones being maintained under super-atmospheric pressure with suitable reforming conditions with the effluent from the first zone being pre-heated prior to contacting in the second zone. The free-oxygen-containing gas may contain nitrogen and may, for example, be air, and the resulting gas mixture, may then be used as an ammonia synthesis gas. The figure shows diagrammatically a suitable embodiment of the invention. Natural gas in line 12 is preheated by passing through a heating coil in furnace 11, and then is mixed in line 14 with sufficient preheated steam from line 13 to give a moles steam/total atoms carbon ratio for the mixture of 2.5 to 7.5 and a residual methane content in the effluent of 5 to 16 mol. per cent on a dry basis (i.e. ignoring steam content). The mixture from line 14 passes into the first reforming zone comprising tube 16 in a radiantly-heated section of furnace 11. The tubes contain a suitable catalyst, preferably containing nickel, e.g. nickel oxide, the pressure is 200-700 p.s.i.g., the residence time is 0.5 to 10 seconds and the outlet temperature 1300-1600 DEG F. The effluent from this zone then passes through line 17 and is heated in 27 to 1500-1525 DEG F. and passes to secondary reformer 19 where it is contacted with 0.4 to 1.6 mols. of steam per mol. of dry gas and 0.25 to 0.75 mols. of air per mol. of dry gas, more steam having been added to the effluent if necessary, under adiabatic conditions on a catalyst 21 similar to that used in the first reforming zone. The pressure is 190-670 p.s.i.g., the residence time greater than 0.5 secs., the outlet temperature is 1600 DEG -1800 DEG F. and the effluent has a methane content of less than 2.0 mol. per cent on a dry basis. A quench of steam and water is introduced via line 24 to cool the hot effluent from bed 21 to the substantially lower temperature required in the downstream waste heat recovery and CO shift conversion equipment (not shown). Reference has been directed by the Comptroller to Specification 975,775.ALSO: A process for the production of a hydrogen rich gaseous mixture comprises contacting a hydrocarbon with steam in a first reforming zone and then contacting the effluent from this zone with steam and an oxygen containing gas in a second reforming zone, both zones being maintained under super-atmospheric pressure with suitable reforming conditions, with the effluent from the first zone being preheated prior to contacting in the second zone. The oxygen containing gas may contain nitrogen and may, for example, be air, and the resulting gas mixture may then be used as an ammonia synthesis gas. The Figure shows diagrammatically a suitable embodiment of the invention. Natural gas in line 12 is preheated by passing through a heating coil in furnace 11, and then is mixed in line 14 with sufficient preheated steam from line 13 to give a moles steam/total atoms carbon ratio for the mixture of 2.5 to 7.5 and a residual methane content in the effluent of 5 to 16 mol per cent on a dry basis (i.e. ignoring steam content). The mixture from line 14 passes into the first reforming zone comprising tubes 16 in a radiantly heated section of furnace 11. The tubes contain a suitable catalyst, preferably containing nickel, e.g. nickel oxide, the pressure is 200 to 700 p.s.i.g., the residence time 0.5 to 10 seconds and the outlet temperature 1300 DEG to 1600 DEG F. The effluent from this zone then passes through line 17 and is heated in 27 to 1500 DEG to 1525 DEG F. and passes to secondary reformer 19, where it is contacted with 0.25 to 0.75 mols of air per mol of dry gas and 0.4 to 1.6 mols of steam per mol of dry gas, more steam having been added to the effluent if necessary, under adiabatic conditions on a catalyst 21 similar to that used in the first reforming zone. The pressure is 190 to 670 p.s.i.g., the residence time greater than 0.5 secs., the outlet temperature is 1600 DEG to 1800 DEG F. and the effluent has a methane content of less than 2.0 mol per cent on a dry basis. A quench of steam and water is introduced via line 24 to cool the hot effluent from bed 21 to the substantially lower temperature required in the downstream waste heat recovery and CO shift conversion equipment (not shown). Reference has been directed by the Comptroller to Specification 975,775.