Heat and Power Integration Opportunities in Methane Reforming based Hydrogen Production with PSA separation

Hydrogen is getting increasing attention by government and industry leaders, [1], as a very environmentally attractive and clean fuel because its oxidation leads only to water formation. There is abundance of hydrogen in nature, although it is only available for exploitation in a combined state, either in water, hydrocarbons, or coal [2]. Its recovery from these natural resources requires the addition of energy, [3]. The most common industrial process for production of hydrogen from methane is steam reforming, [2-4], which involves an overall endothermic reaction of methane and water to produce hydrogen, carbon dioxide and carbon monoxide in equilibrium with the reactants. Optimization of the use of energy in this process leads to reduction of the cost of production of hydrogen and therefore to a faster development of a hydrogen economy [1]. Tindall and King [5] have summarized important factors to keep in mind when designing steam reformers for hydrogen production that include recovering heat from the hot flue gas by preheating the reformer feed and the generation of steam by extracting heat from the reformer outlet process gas. Scholz [2] considers a process block diagram with a unit that he calls the steam/energy system where heat from the flue gas and from the reformed and converted product gas is used for generation of steam and heating of feed gas, water and combustion air. Shahani et al. [6] have suggested alternative design features that include: operating hydrogen plants as a source of steam (from waste heat recovery) apart from their primary purpose of producing hydrogen, on the basis that “up to a point, a steam reformer has the ability to produce steam more efficiently than a conventional boiler”, and also generation of electricity for export from the steam produced. Rajesh et al. [7-8] have presented an integrated approach to obtain possible sets of steadystate operating conditions for improved performance of an existing plant, using an adaptation of a genetic algorithm that seeks simultaneous maximization of product hydrogen and export steam flow rates. Here we carry out heat and power integration studies for a conventional methane reforming based hydrogen production plant with the purpose of finding minimum hot/cold/electric utility cost.