Steam Methane Reformer is the commonest process for producing hydrogen in the world. It currently represents the most efficient and mature technology for this purpose. However, due to the high investment costs, this technology is convenient for large sizes only. Furthermore, the cooling of syngas and flue gas produce a great amount of excess steam, which is usually transferred outside the process, for heating purposes or industrial applications. The opportunity of using this additional steam to generate electric power has been studied in this paper. In particular different power plant schemes have been analyzed, including: (i) a Rankine cycle; (ii) a gas turbine simple cycle; (iii) a gas-steam combined cycle. These configurations have been investigated with the additional feature of CO2 capture and sequestration. The reference plant has been modeled according to the state of art of commercial hydrogen plants: it includes a pre-reforming reactor, two shift reactors and a pressure swing adsorption unit for hydrogen purification. The plant has a conversion efficiency of approximately 75% and produces 145,000 Stm3/hr of hydrogen (equivalent to 435 MW on LHV basis) and 63 t/hr of superheated steam. The proposed power plants generate respectively 22 MW (i), 36 MW (ii) and 87 MW (iii) without CO2 capture. A sensitivity analysis was carried out to determine the optimum size for each configuration and to investigate the influence of some parameters, such as electricity, natural gas and steam costs.

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