Chemical looping combustion (CLC) technology is an innovative energy conversion technology that employs oxygen carriers (OC), typically metal oxides, to burn fossil fuels with a minimal carbon footprint. The performance...
The purpose of this research was to study steam gasification of ash-free coal integrated with CO 2 capture in the presence of a K 2 O catalyst for enhancement of the key water-gas shift reaction and promotion of hydrogen production. To achieve this goal, gasification experiments on ash-free coal (AFC) were carried out at varying temperatures (600, 650, 675, 700, and 750 8C) with a sorbent-to-carbon (CaO/C) ratio of 2 and a catalyst (K 2 O) loading of 0.2 g/g (20 weight percent (wt%)) in a fixed-bed reactor equipped with a gas chromatography analyzer. The sorbent-to-carbon (CaO/C) ratio of 2 is based on dry and ash-free basis. The CaO/C ratio and K 2 O wt% were chosen to maximize hydrogen production based on our previously determined optimal values. The AFC was originally extracted from raw lignite coal using organic solvents, which allowed the sorptionenhanced gasification to be conducted with minimal ash-catalyst interactions. The effect of temperature on the yield and the initial reaction rate were investigated. The optimal reaction temperature of 675 8C was determined. Carbon balance and final carbon conversions were calculated based on the residue analysis. Activation energy was also calculated using intrinsic kinetics of the reaction. In this study, using AFC offered the potential advantage of operating the gasification process with catalyst recycle.
The following study investigates a 3-dimensional numerical model for the heat/mass and charge transfer simulation of a counter-flow planar solid oxide fuel cell to predict and evaluate its performance. The main emphasis in developing present model is to use for design and achieving optimized geometrical and effective parameters. This model can be used for calculation of thermal stresses and the structural design of the cell. Three dimensional transport equations are solved using computational fluid dynamics to simulate the flow field and to calculate species and temperature distribution in the computational domain. All ohmic, thermodynamic and electrochemical heat sources are taken in to account. Mass sources are calculated using the electrochemical reaction of hydrogen. Also the 3-D charge transfer equations are solved to predict the electrical potential distribution in the cell body and current collectors considering three kinds of polarization (ohmic, activation and concentration). To evaluate the model capabilities the results of the present study are compared with the experimental data and its accuracy is analyzed.
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