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The reactivity of coal and biomass has been evaluated by comparing the optical and chemical changes in feed material prior and after the co-gasification. The proximate, ultimate, GCV, low-pressure N 2 sorption isotherm, micropetrography, SEM and EDX spectroscopy analyses are carried out to assess the reactivity of blends of high ash Indian coal and biomass. The relative changes in parameters like surface area, pore size, and pore volume have been correlated with reacted percentage area of coal macerals and cellulose-lignin cellular structures of biomass. The Optimas image processing software is being used to mark the reacted portion of organic constituents and calculated the reactivity percentage. The bottom ash of pure coal has shown the least reacted organic matters, indicating inefficiency of high ash coal due to a large amount of inorganic and inertinite contents that is resisting the oxidation. The reactivity percentage is determined by the petrographic and SEM images, and varies from 36.34 to 99.64% and 6.61–96.22%, respectively. It is summarised that the estimation of percentage alteration of macerals and other micro-organic constituents can be used as one of the practical approaches for the assessment of the reactivity of coal and biomass. The blending ratio 6:4 of coal and press mud has shown the highest reactivity (>99.64%). The values of petrographic and SEM reactivity have shown good correlations with the carbon contents, unreacted vitrinites, mineral matters and biomass remnants. These relations have been taken into account to formulate the proposed petrographic empirically calculated reactivity (R PEC). The focus has also been made to investigate the influence of feed composition on carbon conversion and heating value of the product gas. Image 1 • Relative changes in chemical, morphological and structural parameters of coal and biomass indicate the degree of effective reactivity of the co-gasification. • Petrographic and SEM images are used to measure alterations of organic and inorganic constituents. • Procedures for petrographic and SEM reactivity estimation have been suggested. • Proposed empirically calculated reactivity (R PEC) model can help to assess the reactivity of coal and biomass. [ABSTRACT FROM AUTHOR]

[Display omitted] The transient multiphase model with the Eulerian-Eulerian approach based on the Two-Fluid Model (TFM) was executed to simulate the bubbling regime's hydrodynamics of bed material in the fluidized bed using three different drag models. Coal ash particles having three different sizes were taken in bed for fluidization under cold conditions. The bubbling regime's superficial velocities were acquired from experimentations and used as inlet velocities during Computational Fluid Dynamics (CFD) simulation of a 2-Dimensional fluidized bed. The Syamlal-O'Brien, Gidaspow and Wen-Yu drag models were considered in this study, and their effects on the bed hydrodynamics were discussed. The study emphasized the suitability of drag models for the coal ash particles. The drag force was not adequate and showed a negligible effect on particles irrespective of the high inlet velocity displayed by the Gidaspow model. The other two drag models predicted sufficient drag, but there was more intensity in Syamlal-O'Brien than in the Wen-Yu model. The Syamlal-O'Brien model resembled more physical fluidization occurrences for smaller and larger sized coal ash particles. This study also supports the hydrodynamics of the Geldart-D type particles. [ABSTRACT FROM AUTHOR]

This study presents the synergy of high ash coal with different biomass when blended in different ratios for co-gasification using a fluidized bed gasifier. The moisture, CO 2 , oxygen, hydrogen and numerous other compounds have synergetic effects on the co-gasification because of affinity to heat and prone to reaction. The mineral constituents, discrete mineral species and ion-exchangeable elements present in coal, biomass and bottom ash residue have been identified by XRD, XRF, FTIR and SEM-EDX. The catalytic effects of mineral, major oxides, halides and chlorites content on co-gasification have been assessed. The mineral (e.g. calcite, dolomite, hematite, etc.) present in the high ash coal and biomass plays a catalytic role. Other minerals (e.g. quartz, sulfide, kaolinite and phosphates) negatively influence co-gasification and product gas composition. The positive relationship of CaO, MgO and Fe 2 O 3 with CCE, CGE and increasing heat values also supports major oxides catalytic role. The blend of press mud and high ash coal has given better results due to more Ca, K, Mg and Na elements. SEM microphotographs reveal catalytic effects at the micro-level, indicated by the extensive cracking of hydrocarbon compounds. The empirical models proposed for estimation of catalytic effects of minerals on co-gasification. [Display omitted] • Investigated the mineral catalytic effects of high ash coal on carbon conversion. • FTIR indicates reduction in the functional group due to blending effects. • Moisture, CO 2 , O 2 , H 2 and numerous other compounds have synergetic effects. • SEM shown minerals/oxides catalytic role in micro-cracking of hydrocarbon compounds. • Empirical models proposed for the estimation of catalytic effect of minerals/oxides. [ABSTRACT FROM AUTHOR]