Used 425 Nm3/hr (15,000 SCFH) Hydrogen Plant built by Cotting Industries in 2016. Most equipment is skid mounted. The plant has a double-tube steam methane reformer that is a compact furnace enclosure with a single reaction tube fired on two sides. The furnace enclosure is wide at the bottom to accommodate the burners and tapered at a height several feet above the length of the flames to a narrow upper section. This configuration allows combustion to be completed in the lower section bringing the feed/steam mixture quickly to its reaction temperature. The intermediate side walls channel the flue gas into a turbulent flow condition at the upper section to improve heat transfer and maintain a uniform tube wall temperature along the length of the reaction tube. The reaction tube consists of an annular portion filled with catalyst and a center return tube. The reaction tube is supported from the bottom and allowed to thermally expand upward through the use of a counterweight system attached at the top of the tube. The steam/hydrocarbon feed gas mixture enters the annular section of the reformer reaction tube at the bottom. The feed gas passes upward through the catalyst bed and then downward through the center return tube. Thus, the feed gas flows through the catalyst bed in single pass, co-current heat exchange relationship with the hot combustion gas in the furnace enclosure. Then, the reformed gas flows back to the bottom of the reformer through the center return tube in single pass, counter current heat exchange relationship with the upward flowing feed gas in the catalyst space. The combination of the furnace enclosure geometry and a reaction tube with a center return tube results in an even temperature profile over the length of the tube while maintaining a high thermal efficiency in the furnace.