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This paper presents a novel method to calculate the anisotropic and stress-dependent coal permeability by determining cleat compressibility using the Mercury Intrusion Porosimetry (MIP) and stress-strain measurements. Cleat compressibility is often assumed isotropic and constant in the literature and is usually obtained by numerical fitting to a matchstick permeability model e.g. the model by Seidle, et al. (1992) despite the gross simplification of this representation of the coal pore network. This paper provides a method to calculate anisotropic cleat compressibility using only MIP and stress-strain measurements which are easy to conduct, and without permeability information, which is harder to come by, requiring laboratory experiments on the core or through fitting field data. We report the measured stress-strain behaviour of a coal sample, with hydrodynamic loading/unloading over the range 0.5-4.0 MPa, and the permeability in face cleat (k F ) and butt cleat (k B ) directions using the Triaxial Stress Permeameter (TSR). The stress-strain measurement is used to calculate the anisotropic modulus of elasticity (E F , E B, and E V ) in face cleat, butt cleat and bedding plane directions, and cleat compressibility in the face cleat (C fF ) and butt cleat (C fB ) directions using the fractal dimension analysis with MIP measurement. Finally, the cleat compressibilities are used to calculate the anisotropic coal permeability by Seidle, et al. (1992) permeability model and compared with the measured permeability of the coal sample.

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Gasification is a thermochemical pathway used to convert carbonaceous feedstock into syngas (CO and H2) in a deprived oxygen environment. The process can accommodate conventional feedstock such as coal, discarded waste including plastics, rubber, and mixed waste owing to the high reactor temperature (1000 °C-1600 °C). Pyrolysis is another conversion pathway, yet it is more selective to the feedstock owing to the low process temperature (350 °C-550 °C). Discarded tyres can be subjected to pyrolysis, however, the yield involves the formation of intermediate radicals additional to unconverted char. Gasification, however, owing to the higher temperature and shorter residence time, is more opted to follow quasi-equilibrium and being predictive. In this work, tyre crumbs are subjected to two levels of gasification modelling, i.e. equilibrium zero dimension and reactive multi-dimensional flow. The objective is to investigate the effect of the amount of oxidising agent on the conversion of tyre granules and syngas composition in a small 20 kW cylindrical gasifier. Initially the chemical compositions of several tyre samples are measured following the ASTM procedures for proximate and ultimate analysis as well as the heating value. The measured data are used to carry out equilibrium-based and reactive flow gasification. The result shows that both models are reasonably predictive averaging 50% gasification efficiency, the devolatilisation is less sensitive than the char conversion to the equivalence ratio as devolatilisation is always complete. In view of the high attained efficiency, it is suggested that the investigated tyre gasification system is economically viable.