Hydrogen Production from Natural Gas (Steam Reforming)

The process under analysis comprises two major sections: (1) Steam reforming; and (2) Hydrogen purification.

Steam reforming. First, natural gas passes through a desulfurization step with recycled Hydrogen for removal of organic sulfur compounds that poison the catalysts used in the reaction downstream. The desulfurized gas is mixed with steam generated through heat integrations and fed to the Pre-Reformer, where higher hydrocarbons found in the feed gas are converted into a methane-rich gas and hydrogen. This step prevents catalysts employed downstream from having its activity decreased by the presence of higher hydrocarbons. This pre-reformed gas is fed to the Steam-Reformer. There, methane is converted to syngas in a steam reforming, where methane reacts with steam in the presence of a nickel-based catalyst, generating CO and Hydrogen.

Hydrogen purification. The outlet from the steam reformer is then fed to a shift converter, where carbon monoxide is reacted with steam, producing carbon dioxide and additional Hydrogen. The shifted gas is then cooled to near ambient temperature, and its residual water condenses and is removed in a knockout drum. Finally, the Hydrogen is purified from carbon dioxide and other impurities by means of a pressure swing adsorption (PSA) system. A small portion of the pure Hydrogen from the PSA is compressed and recycled to the Desulfurization area upstream. The remaining Hydrogen is finally directed to the downstream consumers plants via pipeline.