Autothermal reforming of palm empty fruit bunch bio-oil: thermodynamic modelling

This work focuses on thermodynamic analysis of the autothermal reforming of palm empty fruit bunch (PEFB) bio-oil for the production of hydrogen and syngas. PEFB bio-oil composition was simulated using bio-oil surrogates generated from a mixture of acetic acid, phenol, levoglucosan, palmitic acid and furfural. A sensitivity analysis revealed that the hydrogen and syngas yields were not sensitive to actual bio-oil composition, but were determined by a good match of molar elemental composition between real bio-oil and surrogate mixture. The maximum hydrogen yield obtained under constant reaction enthalpy and pressure was about 12 wt% at S/C = 1 and increased to about 18 wt% at S/C = 4; both yields occurring at equivalence ratio Φ of 0.31. The possibility of generating syngas with varying H2 and CO content using autothermal reforming was analysed and application of this process to fuel cells and Fischer-Tropsch synthesis is discussed. Using a novel simple modelling methodology, reaction mechanisms were proposed which were able to account for equilibrium product distribution. It was evident that different combinations of reactions could be used to obtain the same equilibrium product concentrations. One proposed reaction mechanism, referred to as the ‘partial oxidation based mechanism’ involved the partial oxidation reaction of the bio-oil to produce hydrogen, with the extent of steam reforming and water gas shift reactions varying depending on the amount of oxygen used. Another proposed mechanism, referred to as the ‘complete oxidation based mechanism’ was represented by thermal decomposition of about 30% of bio-oil and hydrogen production obtained by decomposition, steam reforming, water gas shift and carbon gasification reactions. The importance of these mechanisms in assisting in the eventual choice of catalyst to be used in a real ATR of PEFB bio-oil process was discussed

Numerical investigation of methane combustion under mixed air-steam turbine conditions – FLAMESEEK

Lowering emissions from power generating gas turbines, while retaining efficiency and power output, constitutes a formidable task, both at fundamental and technical levels. Combined gas turbine cycles involving air humidification are particularly attractive, since they provide additional power with improved efficiency. Water or steam addition promotes the reduction of nitrogen oxides emissions, for both the premixed and non-premixed modes of operation. Consequently, there is an urgent need for thorough understanding of the combustion chemistry and flow-chemistry interaction under high pressure and high humidity conditions as well as simulating the turbulent flow field with realistic chemistry. Both objectives require the development of reduced kinetic mechanisms.\ud \ud Reduced mechanisms for methane combustion valid for high pressure and high humidity are developed here, using the CSP (computational singular perturbation) method. The effects of humidity and pressure on the dynamics of NO formation pathways are discussed. A reaction progress variable model for the simulation of turbulent combustion is also developed, valid for adiabatic, non-adiabatic, premixed as well as partly or non-premixed combustion of various fuels, including natural gas, hydrogen and syngas. The model utilizes the CSP methodology for accurate mapping of the pertinent thermochemical data on a set of two reaction progress variables. Preliminary results are displayed