Hydro-Desulphurization - Sour Water
Hydrogen Production
Refineries contain many processes that consume hydrogen (hydrotreaters and hydrocrackers) and those that produce hydrogen (catalytic reformers). In most cases, however, the demand for high-purity hydrogen exceeds the supply. The difference is made up by the Hydrogen Plant.
Hydrogen production is accomplished by steam reforming methane, followed by shift conversion and methanation. Sulfur is a severe catalyst poison and must be removed.
Steam reforming occurs at temperatures of approximately 1500˚F (815˚C) in the presence of a nickel based catalyst inside tubes of a direct fired furnace. It produces hydrogen, CO and CO2 from steam and methane.
Following steam reforming, shift conversion takes place in a reactor consisting of an iron or iron/chromium catalyst. It uses more steam to convert CO to CO2 in the process creating more hydrogen. CO and CO2 are scrubbed from produced hydrogen using potassium carbonate.
Since CO and CO2 are poisons to some catalyst used in refining processes, methanation is used as the final step to remove them from hydrogen. Methanation uses hydrogen and a nickel based catalyst to convert CO and CO2 into methane. The resulting hydrogen is typically 95% pure.
