Gasification of coal is gaining more popularity due to its clean operation, and its ability to generate products for various markets. However, these technologies are not widely commercialized due to reliability and economic issues. Mineral matter in coal plays an important role in affecting the availability/reliability of a gasifier. Agglomeration in the bed, slag mobility and blockage of the syngas exit section are some of the operations related concerns in fixed-bed gasifiers, while ash deposition and sudden defluidization are the major concerns in fluidized bed gasifiers. In the case of entrained flow gasifiers, syngas cooler fouling and blockage, corrosion and erosion of refractory, and slag mobility are some of the major issues affecting the operations and the reliability of the gasifier. This review is aimed at critically examining various mineral matter related issues contributing to the operation and reliability problems in three types of generic gasifiers (fixed bed, fluidized bed and entrained flow gasifiers). Based on the review, some strategies to counter the potential mineral matter related issues are presented.

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A single-parameter empirical method, based on the effective carbon number concept, was developed to predict the viscosities of defined (alkanes, alkenes, aromatics, alicyclics, and hydrocarbon mixtures) and undefined (coal liquids and coal liquid fractions) hydrocarbon liquids at various temperatures and for pressures up to 700 bar. The only parameter required for estimating the viscosities of a hydrocarbon system is the effective carbon number, which can be obtained from a single liquid viscosity datum of the compound using one of two proposed correlations, that is, n-alkane correlation or aromatic correlation. Also, experimental data on the viscosities of laboratory-generated coal liquid oils were generated and used in the evaluation of the model. The new method, when tested on viscosity data of defined and undefined hydrocarbon liquid compounds at various pressures and temperatures, yielded an overall average absolute deviation (AAD) of 4.11% and 9.99%, respectively. The model was also found to compare favorably with other methods available in the literature.