Energy and exergy analysis as tools for optimization of hydrogen production by glycerol autothermal reforming

Abstract

International audienceIn this work, various assessment tools were comprehensively applied to investigate hydrogen production via glycerol autothermal reforming. These tools are used to study the chemical reactions, design and simulate the entire hydrogen production process, investigate the energetic and exergetic performances of the processes and perform parametric analyses (using intuitive and design of experiment-based methods). Investigating the chemical reactions of autothermal reforming (ATR) of glycerol reveals that the optimal conditions, based on maximizing the hydrogen production, minimizing the methane and carbon monoxide contents and eliminating coke formation at thermoneutral conditions, can be achieved at a water glycerol feed ratio (WGFR), reforming temperature (T) and oxygen-glycerol feed ratio (OGFR) of 9, 900 K and 0.35, respectively. The energetic study of the resulting process indicates that approximately two-thirds of the energy fed to the process is recovered in the useful product (H-2) and that the remaining incoming process energy is exhausted in the off-gas. The exergetic investigation reveals that the exergetic efficiency of the ATR process is 57% and that 152 kJ are destroyed to generate 1 mol of hydrogen. The process operating conditions recommended by the chemical reaction investigation suffers from low performance because energetic and exergetic efficiencies are comparatively lower than values previously reported in literature for other reformates. The parametric investigation indicates that more accurate conditions are needed to convert glycerol hydrogen. These conditions ensure the lowest consumption of energy to generate a given amount of hydrogen. This paper recommends WGFR = 5.5, T = 900 K and OGFR = 0.96 as the optimum conditions for the entire glycerol-to-hydrogen process. For this configuration, the thermal and exergetic efficiencies are 78.7% and 67.8%, respectively

Analysis and optimisation of H2 production from crude glycerol by steam reforming using a novel two step process

“…However, the works studying the catalytic steam reforming of crude glycerol [6,[13][14][15][16][17] are scarce. The crude glycerol used in these works, apart from glycerol, was made up of methanol, inorganic salts, polyglycerols and fatty acid impurities.…”

Sustainability assessment of photobiological hydrogen production using anaerobic bacteria (Rhodospirillum rubrum) via exergy concept: Effect of substrate concentrations

“…Such energy and exergy approaches have also been applied by Hajjaji et al . for optimization of hydrogen production through glycerol autothermal reforming. Recently, Romero‐Paredes et al .…”

“…In another survey, Balta et al [16] assessed the efficiency of a solar energy system coupled with Mg-Cl thermochemical cycle for hydrogen production using energy and exergy analyses. Such energy and exergy approaches have also been applied by Hajjaji et al [17] for optimization of hydrogen production through glycerol autothermal reforming. Recently, Romero-Paredes et al [18] applied exergy, as well as, anergy concepts separately for thermochemical production of hydrogen employing nuclear power through sulfur-iodine cycle.…”

Single stage H2 production, purification and heat supply by means of sorption-enhanced steam reforming of glycerol. A thermodynamic analysis

“…Some technologies have been proposed in literature to yield H 2 from glycerol, among which we could mention steam reforming, partial oxidation, autothermal reforming, dry reforming and supercritical water gasification (Dieuzeide and Amadeo, 2009;Freitas and Guirardello, 2014;Galera and Gutiérrez Ortiz, 2015;Hajjaji et al, 2014).…”