Article Open Access CHARACTERIZATION AND ASH CHEMISTRY OF SELECTED NIGERIAN COALS FOR SOLID FUEL COMBUSTION (original) (raw)
Related papers
Characterization and Ash Chemistry of Selected Nigerian Coals for Solid Fuel Combustion
2017
In this paper, characterization and ash chemistry of selected Nigeria coal samples were investigated to determine its suitability as a solid fuel. The three coal samples considered originated from Northern Benue trough, Central Benue trough and Anambra Basin of Nigeria where proven reserve deposits are found. The coal samples were analysed using various analytical methods such as thermosgravimetric analysis (TGA) and X-ray Fluorescence spectroscopy (XRF) analyses. The ash chemistry indices used in predicting the performance of the coal samples includes basic to acidic oxide (B/A), silica ratio, iron index and sulphur slagging index (Rs). The TGA profile suggests that Enugu coal showed high thermal stability than that of Okaba and Maiganga coals but had an ash content higher by a factor of 2.0 when compared with Okaba and Maiganga coals. Maiganga coal however has the highest heating value of 27.40 MJ/kg when compared to Okaba coal (25.74 MJ/kg) and Enugu coal (22.92 MJ/kg). The silic...
In this study, the physicochemical, microstructural, mineralogical, thermal, and kinetic properties of three (3) newly discovered coals from Akunza (AKZ), Ome (OME), and Shiga (SHG) in Nigeria were examined for potential energy recovery. Physicochemical analysis revealed high combustible but low levels of polluting elements. The higher heating values (HHV) ranged from 18.65 MJ/kg (AKZ) to 26.59 MJ/kg (SHG). Microstructure and mineralogical analyses revealed particles with a rough texture, surfaces, and glassy lustre, which could be ascribed to metals, quartz, and kaolinite minerals. The major elements (C, O, Si, and Al), along with minor elements (Ca, Cu, Fe, K, Mg, S, and Ti) detected are associated with clays, salts, or the porphyrin constituents of coal. Thermal analysis showed mass loss (M L ) ranges from 30.51% – 87.57% and residual mass (R M ) from 12.44% – 69.49% under combustion (oxidative) and pyrolysis (non-oxidative) TGA conditions due to thermal degradation of organic ma...
Pyrolysis-GC Analysis of some Coals from Benue Trough, Nigeria
An open system pyrolysis-GC was performed on some coal samples from the Benue Trough, Nigeria; the evolved hydrocarbons were identified and quantified using n-butane as internal standard. This, combined with petrography and Rock-Eval pyrolysis were used in assessing the hydrocarbon generating potentials of the coal samples. Lafia-Obi coals were found to have a percentage vitrinite reflectance (%Ro) values of 0.91-1.08 %, maximum temperature for hydrocarbon generation (Tmax) of 449-455 ºC and a hydrogen Index (HI) of 136-246 mg HC/g TOC, suggesting that they are in their late maturity stage for hydrocarbon generation, while Lamza and Kumo coals, with %Ro of 0.52-0.70% and 0.36-0.59%; Tmax of 434-438 °C and 415-429 °C; and HI of 184-269 mg HC/g TOC and 167-322 mg HC/g TOC, are at the early maturity and immaturity stage, respectively. The HI values show that the Lafia-Obi coals are mainly of type III kerogen, Lamza coals are mixtures of type III and type II/III, while Kumo coal are mai...
2020
This study examined the geomineralogical, physiochemical, thermal, and kinetic characteristics of selected coals from Chikila (CHK), Lafia Obi (LFB) and Okaba (OKB) in the Benue Trough and Anambra Basins of Nigeria. Physicochemical characterisation revealed significant quantities of carbon, volatiles, fixed carbon, and heating values (25–30 MJ/kg) but low moisture, and ash contents. The fuel properties indicate subbituminous to bituminous rank coals. The morphological, microstructure and elemental analyses revealed heterogeneous sized coal particles with a glassy sheen due to clay and aluminosilicate minerals such as quartz, alumina, kaolinite, and hematite. Based on thermal analysis, the coal samples are highly reactive and experienced significant thermal degradation as evident in the high mass losses (ML = 91.59 – 94.04%) and low residual masses (RM = 5.96% 8.41%), which are observed in the orders LFB > OKB > CHK for ML and CHK > OKB > LFB for RM. LFB experienced the h...
Coal being an economic deposit can be used for various purposes depending on their properties and composition. Hence, the need to carry out detail investigation on Ankpa coals. Ankpa coals fall within the Mamu Formation of Anambra Basin in southeastern Nigeria. The coals were investigated to deduce the rank and the coal quality with respect to power generation, cokability, handling, fueling, combustion, agglomeration and slagging potential. Nine coal samples were collected from two boreholes (BH-2) and (BH-4) having depth of 16.5m and 27.4m respectively and were subjected to proximate, ultimate and elemental analyses. Moisture content ranges from 2.10 to 8.75 wt%, Ash content, 4.45 to 26.8 wt%, volatile matter, 40.10 to 56.9 wt% and the fixed carbon 20.45 to 39.24 wt%. The moderate moisture, low to high ash content and high volatiles matter in the coals suggest high volatile sub-bituminous, non coking coal. The carbon content range from 23.3 to 52.4%, hydrogen, 1.73 to 6.88%, oxygen, 9.57 to 18.9%, Nitrogen, 1.42 to 2.93% and sulphur, 0.73 to 4.15 %. The sulphur content (> 0.8%) and Nitrogen content (>1.5%) indicates non coking coal and would pollute the atmosphere during combustion by releasing flue gases. The agglomeration and slagging were deduced by the ratio of C/H, FC/V, SiO2/Al2O3, Fe2O3/CaO, Silica ratio (G), and Base/Acid ratio (B/A). The agglomeration level and tendency of the coals to slag varies from weak-strong. The coals are not suitable for coking but can be used for power generation, combustion applications and fuelling due to it high combustibility.
Chemical and Pyrolytic Thermogravimetric Characterization of Nigerian Bituminous Coals
GeoScience Engineering, 2016
The discovery of new coal deposits in Nigeria presents solutions for nation’s energy crises and prospects for socioeconomic growth and sustainable development. Furthermore, the quest for sustainable energy to limit global warming, climate change, and environmental degradation has necessitated the exploration of alternatives using cleaner technologies such as coal pyrolysis. However, a lack of comprehensive data on physico-chemical and thermal properties of Nigerian coals has greatly limited their utilization. Therefore, the physico-chemical properties, rank (classification), and thermal decomposition profiles of two Nigerian bituminous coals – Afuze (AFZ) and Shankodi-Jangwa (SKJ) – were examined in this study. The results indicate that the coals contain high proportions of
Fuel Characteristics of Duduguru Coal from Nasarawa State in Nigeria
2019
The discovery of vast deposits of various ranks of coal in Nigeria presents significant opportunities to address the nation’s persistent energy crises. However, the lack of comprehensive data on the physicochemical, calorific, microstructural, mineralogical, and thermal properties of Nigerian coals remains a significant challenge. Therefore, this paper seeks to investigate the fuel characte ristics and energy recovery potential of a newly discovered coal from Duduguru in Obi Local Government Area of Nasarawa State, Nigeria. Results revealed that Duduguru (DDG) coal contains high carbon (59.6%), oxygen (32.9%), volatile matter (76.4%), fixed carbon (16.6%) and higher heating value (HHV = 26.6 MJ/kg), but low nitrogen (1.3%), sulphur (0.6%), moisture (6.5%), and ash (0.5%) content. Based on these properties, DDG is classified as a non-agglomerating, sub-bituminous, grade “A” coal with potentials for electricity generation, cement production, among others. The mineralogical analyses re...