|
General comment This process represents a set of unit processes for a small-scale modular Steam Methane Reforming (SMR) system that produces high-purity hydrogen using city gas (natural gas, NG), water, and electricity as inputs. The final hydrogen product has a purity of 99.999%, and the product hydrogen outlet pressure is set at 30 bar.
The city gas is first subjected to a desulfurization process to remove sulfur compounds and is then supplied to the steam methane reformer. Water is treated and converted into steam through the water treatment and steam generation processes before being fed together with the natural gas. In the steam methane reformer, methane, the main component of the city gas, reacts with steam at a high temperature of approximately 700–900°C to produce reformate gas consisting mainly of carbon monoxide and hydrogen. The heat required for the reforming reaction is supplied by combusting city gas and off-gas recovered from downstream processes in the reformer burner.
The reformate gas is then supplied to the shift reactor, where carbon monoxide reacts with steam through the water-gas shift reaction to form carbon dioxide and additional hydrogen. After the shift reaction, the reformate gas is cooled in a cold box, where the moisture contained in the gas is condensed and separated into gaseous and liquid phases.
The cooled and gas-liquid separated reformate gas is subsequently supplied to a Pressure Swing Adsorption (PSA) unit, where impurities such as carbon dioxide, unreacted methane, and residual carbon monoxide are removed by adsorption. As a result, a high-purity hydrogen product with a purity of 99.999% and an outlet pressure of 30 bar is produced.
The off-gas separated in the PSA process is recycled to the steam methane reformer burner as an auxiliary fuel and utilized as a process heat source. Gaseous emissions, including carbon dioxide generated from fuel combustion and the reforming process, are released to the atmosphere, while the water condensed and separated in the cold box is discharged as an aqueous emission (H₂O). |
