Shashi Kumar*, Nisha Katiyar, Surendra Kumar, and Snigdha Yadav Exergy Analysis of Oxidative Steam Reforming of Methanol for Hydrogen Producton: Modeling Study Abstract: Hydrogen production by oxidative steam reforming of methanol in a fixed bed catalytic reactor was modeled and simulated. The addition of O 2 to feed reduced the temperature in the reformer. 99.86% conver- sion was obtained at 550 K and S/C molar ratio of unity in steam reforming while it is at 540 K in oxidative steam reforming. Although H 2 and CO yields were decreased in oxidative steam reforming in comparison to steam reforming, the reductoin H 2 yield was note significant whereas reduction in CO was appreciably high. The ther- mal and exergy efficiencies were favored by reforming temperature and S/C molar ratios. However, variation in S/C molar ratio showed negligibly small effect on efficiencies. The reforming temperature had a notable influence on the efficiencies. The exergy destruction was found to be lower at higher temperature and S/C molar ratio. Thus, oxidative steam reforming of methanol at 540 K and S/C molar ratio of unity utilizes sufficient amount of input energy in the form of useful work and thermodynamic irreversibilities in the reactor are quantitatively small. Keywords: reforming, modeling, exergy efficiency, thermal efficiency, exergy destruction, hydrogen efficiency *Corresponding author: Shashi Kumar, Chemical Engineering Department, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India, E-mail: sashifch@iitr.ernet.in Nisha Katiyar: E-mail: nisha.iitr@gmail.com, Surendra Kumar: E-mail: skumar@iitr.ernet.in, Snigdha Yadav: E-mail: Snigdha. yadav@gmail.com, Chemical Engineering Department, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India 1 Introduction Fuel cells are worldwide recognized as a leading power- generating engines, mostly used in mobile and stationary applications. Hydrogen, which is main fuel to fuel cell, is considered as an important energy carrier that reduces the impact on environment [1–3]. Hydrogen is produced from a variety of processes including reforming of hydrocarbon fuels, water electro- lysis, coal gasification, and partial oxidation of heavy oils [4]. For fuel cell, hydrogen can be efficiently pro- duced on board by the reforming of hydrocarbons with reduced emission of pollutants. In order to reduce the production cost, renewable energy sources are consid- ered as viable long-term energy sources for hydrogen production [5]. Methanol, a renewable energy source, has certain advantages when compared to other hydro- carbons like natural gas, higher hydrocarbons, and oxy- genated hydrocarbons. Methanol has high H:C ratio and no C:C bond. The biomass resources can also be used to produce methanol. Its reforming requires relatively low temperature levels and is free of oxides of sulfur that usually appear in methane and gasoline reforming [2, 6]. There are mainly five reforming methods for convert- ing methanol into hydrogen rich gas: steam reforming of methanol (SRM), partial oxidation reforming of methanol (POM), autothermal reforming (ATR), methanol decompo- sition (MD), and oxidative steam reforming of methanol (OSRM). Among these processes, SRM and MD are endothermic reactions limited by external heat transfer, POM is the exothermic reaction, whereas ATR and OSRM combine the endothermic SRM reaction with the exother- mic POM reaction [7–9]. The exergy is the property of the system that enables to determine the work potential of energy contained in the system at the specified state. The work potential is the maximum useful work that can be obtained from the system. The system does the maximum possible work when it undergoes a reversible process from the specified initial state to the state of its environment. Therefore, there will always exist the difference between exergy and the actual work delivered by the system. The exergy analysis is carried out on the basis of second law of thermodynamics with reference to the environmental conditions [10, 11]. doi 10.1515/ijcre-2012-0073 International Journal of Chemical Reactor Engineering 2013; 11(1): 1–12 Brought to you by | Indian Institute of Technology Roorkee Authenticated | 59.163.196.43 Download Date | 12/13/13 2:28 PM