Energy Analysis in Combined Reforming of Propane

Combined (steam and CO2) reforming is one of the methods to produce syngas for different applications. An energy requirement analysis of steam reforming to dry reforming with intermediate steps of steam reduction and equivalent CO2 addition to the feed fuel for syngas generation has been done to identify condition for optimum process operation. Thermodynamic equilibrium data for combined reforming was generated for temperature range of 400–1000°C at 1 bar pressure and combined oxidant (CO2 + H2O) stream to propane (fuel) ratio of 3, 6, and 9 by employing the Gibbs free energy minimization algorithm of HSC Chemistry software 5.1. Total energy requirement including preheating and reaction enthalpy calculations were done using the equilibrium product composition. Carbon and methane formation was significantly reduced in combined reforming than pure dry reforming, while the energy requirements were lower than pure steam reforming. Temperatures of minimum energy requirement were found in the data analysis of combined reforming which were optimum for the process. 1. Introduction Syngas (H2 + CO) is an important commodity for various applications. It is used as fuel in internal combustion (IC) engines [1–5], raw material for chemical manufacture by FT synthesis to produce hydrocarbons [6–9], for synthesis of liquefied petroleum gas (LPG) [10, 11], gasoline [12], alcohols [13–18], dimethyl ether [19–21], methanethiol [22], and also as a fuel for SOFC in fuel cells [23, 24]. It has been used as raw material as fuel in gas turbines [25–27], for use in coal liquefaction [28], for use in cofiring and reburning in a coal fired boiler [29], and also to synthesize biofuels by syngas fermentation [30]. Solid oxide fuel cell (SOFC) has the unique distinction of using syngas instead of pure hydrogen for electricity generation as it treats CO equivalent to hydrogen in feed [31]. Although some researchers have reported lower efficiencies with CO compared to hydrogen, the cost of pure hydrogen production can always cap these results for cheap power generation from SOFC [32–34]. Steam reforming (SR) [35, 36] and dry reforming (DR) [37] are well-known processes for syngas/hydrogen generation [38]. SR is preferred for hydrogen generation, and DR is preferred for syngas generation. The total moles of syngas generated are of importance for SOFC feed from the hydrocarbon fuel, and these processes generate equivalent amount of syngas from fuels and hence are comparable [39–41]. But both these processes are highly endothermic and also have their inherent drawbacks. SR requires huge