Indian Coal Research Articles

Estimation of Fly ASH Availability in a Thermal Power Plant for Cement Manufacturers

The Indian coals are having 25 to 45% ash content and huge quantity of fly ash is being generated every day in the Indianthermal power plants. The fly ash so generated are being disposed by dry or wet mode from the power plant. The fly ashdisposed in dry mode is lifted by the cement manufacturers and the fly ash disposed in wet mode is unattended. Mostof the quantity of fly ash is collected in the ESPs. The particle size of fly ash collected in ESPs is finer compared to the flyash collected in other parts of the power plant. For this reason the cement manufacturers prefer the fly ash from ESPs.The quantity of fly ash collected in the ESPs is not directly measurable on everyday basis as there are no well proveninstrumental methods. Also the quantity of fly ash collected in ESPs fluctuates every day due to the varying load factorand coal quality. However, it is important to estimate the quantity of fly ash collected by ESPs on everyday basis so thatthe proportion of fly ash lifted by the cement manufacturers and the fly ash sent to the ash pond will be known. Presentlypower plants do not have a method to estimate the exact availability of fly ash and it is being theoretically calculated fromthe design value that the 80% of the total ash is fly ash and in that a fixed proportion (about 70% of total fly ash generated)is collected in the ESPs. However, the actual generation of fly ash would be different and this is influenced by the type ofcoal used, fineness of the input coal particles, boiler operating conditions, load factor, age of the power plant, etc. Thisuncertainty leads to disputes between cement manufacturers and the utility if there is a penalty clause in the agreementfor not completely lifting the available fly ash (as theoretically calculated by the utility). In view of this it is imperative toformulate acceptable methods for determining the actual quantity of fly ash collected in the ESPs on daily basis. In thepresent work, a simple methodology was developed to quantity the average fly ash collected in ESPs in a 210 MWe coalfired power plant on every day basis through site measurements and routine power plant data. The amount of fly ashdisposed in dry and wet mode has also been estimated through this method.

Prevalence of Hypothyroidism in the Population of West Bokaro Coal Mine Area, Jharkhand: A Hospital-Based Observational Study.

BackgroundHypothyroidism is a common endocrine disorder worldwide. Studies on the prevalence of hypothyroidism in different geographical territories of India are sparse. Data on the prevalence of hypothyroidism in India's coal mine areas are lacking. Therefore, we conducted a cross-sectional study to determine the prevalence of hypothyroidism in the adult population living in the coal mine areas of West Bokaro, Jharkhand, India.MethodsIn total, 1484 individuals of both sexes attending the outpatient department (OPD) of Tata Central Hospital, West Bokaro, Jharkhand, with varied symptoms were screened for thyroid-stimulating hormone (TSH) levels from January 2021 to February 2022. The age of the study participants ranged from 15 to 80 years.ResultsIn total, 366 participants had hypothyroidism (subclinical as well as overt). The prevalence of hypothyroidism was greater in women than in men. Among the 366 patients with hypothyroidism, 311 were women and 55 were men, and the ratio was 5.5:1. The percentage of the population having hypothyroidism was 24% in this study, which is higher than that reported in other parts of India; however, our results are similar to those of a study conducted in Assam in 2017. Among patients with high TSH levels, 47%, 25%, and 19% had TSH in the range of 5.6-7.5, 7.6-10.6, and 10.6-20 μU/mL, respectively.ConclusionsSubclinical and overt hypothyroidism are common in eastern India. Patients with undiagnosed fatigue and weight gain must be screened for TSH levels. Hypothyroidism is no longer a rarity, and coal mine areas are no exception to this phenomenon. A population‑based epidemiological study of thyroid disorders in coal mine areas is an urgent need.

Implication of nuclear analytical techniques for the assessment of coal quality in terms of ash content

ABSTRACT The manuscript deals with the utilization of Neutron Activation Analysis (NAA), external (in air) Particle Induced Gamma-ray Emission (PIGE) and X-Ray Fluorescence (XRF) for comprehensive characterization of Indian coal in order to evaluate their quality in terms of ash contents. NAA was used involving short irradiation at Pneumatic Carrier Facility (PCF) at Dhruva reactor, India, for determination of Na, Mg, Al and K; whereas long irradiation at Apsara-U reactor was used for estimation of Fe and Ca. External PIGE was applied for quantification of low Z elements (Na, Mg, Al and Si). Method was validated using coal-based standard reference materials: NIST 1635a and 1633c. Comparative evaluation was also carried out using Energy Dispersive X-Ray Fluorescence (EDXRF) spectroscopy. Total concentration of Na, Mg, Al, Si, K, Ca, Ti and Fe oxides has been used as markers for identifying the quality of coal in terms of coal ash contents. Elements such as Sc, Cr, Co, Zn, Se, Cs, Ce, Sm, Hf, U and Th were determined at trace level using conventional NAA techniques after long irradiation at Apsara-U reactor. The coal with higher ash content was found to contain high concentration of trace elements and the better quality coal contains lower concentration of trace elements.

Pyrolysis of low‐rank coal: Thermo‐kinetic analysis and product characterization

AbstractPyrolysis, the primary process accompanying the thermal degradation of coal, is complicated, and understanding this process requires kinetic analysis followed by product characterization. In this context, the present work involves the study of kinetics and thermodynamics of low‐rank Indian coal from thermogravimetric analysis data followed by batch pyrolysis and subsequent analysis of the liquid products. The thermal degradation of the coal sample has been carried out using a thermogravimetric analyzer from ambient temperature to 1350 K at five different heating rates (5, 10, 15, 20, and 25⁰C/min) under N2 atmosphere. The kinetic triplets (E, A, and n) are evaluated using the order‐based model‐fitting method. The result of this work shows that coal pyrolysis satisfies the first‐order kinetics mechanism with an average activation energy of 62.141 kJ/mol and a pre‐exponential factor of 123.835 min–1. Thermodynamic parameters such as average enthalpy change (ΔH), entropy change (ΔS), and free energy change (ΔG) of coal pyrolysis are calculated to be 56.1716 kJ/mol, –225.524 kJ/mol/s, and 1.6212 × 105 kJ/mol, respectively. A Batch pyrolysis study of coal was carried out in a semi‐batch reactor at different temperatures with an optimum oil yield of 18.94 wt% at 450°C. The chemical composition of pyrolytic oil was investigated by the FTIR and GC‐MS analysis confirmed the presence of D‐Limonene as the major constituent in the coal pyrolytic oil.

Study of co-pyrolysis kinetics, synergetic effects, and thermodynamics of coal and biomass blends

ABSTRACT The present work investigates the thermochemical conversion characteristics, reaction kinetics, and thermodynamic behavior of coal and biomass (Rice husk (RH)) blend pyrolysis in a TG reactor. Three different proportions of biomass (75, 50, and 25%) are blended with sub-bituminous Indian coal for the co-pyrolysis study. Pure coal and pure RH pyrolysis is characterized by three reaction stages, whereas the blended sample shows a four-stage thermal degradation reaction. A significant synergy is not found in the present study. Model-free techniques (FWO, KAS, and Starnik) are used to estimate the activation energy for various blending mixtures of the feed samples. The activation energy obtained for the equal mass ratio of coal and RH using the KAS, FWO, and Starnik methods is 61.45, 76.58, and 75.54 kJ/mol, respectively. The reaction order for coal: RH blend 25:75, 50:50, and 75:25 is estimated to be 4, 2.4, and 1.3, respectively. The favorable activation energy (Eα ) is found for the blending mixture of 50% coal and 50% RH. The positive value of ΔH indicates the endothermic nature of pyrolysis. The positive and negative values of ΔS indicate the complexity and nonspontaneous nature of coal and biomass blend pyrolysis. The average Entropy (ΔS) for an increasing % of coal is decreasing and the value comes to negative for 75% coal, indicating that thermal equilibrium is favorable for a higher % of coal.

Qualitative surface characterization of Indian Permian coal using XPS and FTIR

ABSTRACT This paper reports on the surface properties associated with high-ash Indian Permian coal, which primarily depend on its geochemical compositions. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) techniques have been used to assess surface properties. The results confirm the presence of different elements, mineral phases, and organic functional groups in coal. The XPS survey confirms the presence of different elements on the surface of the coal. Some of them are C 1s (286.0 eV), O 1s (534.5 eV), N 1s (399.9 eV), S 2p (158.2 eV), such as SiO2 and Al2O3, which correspond to Si 2p (102.7 eV) and Al 2p (75.6 eV) with other clay minerals. XPS spectra of C 1s confirm the presence of aliphatic and aromatic carbon, which are hydrophobic compared to hydrophilic groups such as alcoholic, carboxylic, and phenolic. FTIR also validates the existence of hydrophobic functional groups as being higher than hydrophilic groups. Proximate and ultimate analysis results also confirm the presence of less moisture and a higher carbon percentage in the coal samples. Hence, the inherent hydrophobicity of the coal surface is excellent, and the surface hydrophobicity of coal can also be characterized using XPS and FTIR techniques. This information about the coal properties will be very beneficial for coal beneficiation and utilization.

Ventilation Air Requirement for Mass-Production Panels (MPPs) in Indian Coal Mines: A Critical Appraisal

Ventilation Air Requirement for Mass-Production Panels (MPPs) in Indian Coal Mines: A Critical Appraisal

Assessing the viability of decarbonising India's nitrogenous fertiliser consumption

The fertiliser sector in India is essential to its economy and for its food security. Despite being the second largest global producer of fertilisers, substantial imports of raw materials and fertilisers are required to bridge the demand gap for N–P–K fertilisers in India. Islanded green ammonia production in India shows significant potential to provide a carbon-free source of nitrogen for fertiliser production that will reduce India's imports of both nitrogenous fertilisers and the raw materials required for its production. Green ammonia production also carries many socioeconomic benefits compared to conventional production, such as enhanced job creation, reduced feedstock importation and air pollution. Using an existing islanded green ammonia production model, and applying it across India at a 1.0° (110.6 km) resolution using ERA5 (European Centre for Medium-Range Weather Forecasts Reanalysis 5th Generation) solar irradiance, windspeed and temperature data as an input. A heatmap of the achievable levelized cost of ammonia (LCOA) is then created, identifying areas which show strong potential for green ammonia production. Three scenarios for the levelised cost of electricity (LCOE) reduction are considered and a more detailed analysis is performed on five locations of particular economic and social interest. These results are then used as the present value of ammonia to benchmark the cost of islanded production of ‘green urea’ against conventional means. The major price distortions in the Indian coal and gas markets are identified and stripped out to compare the relative costs of urea production. By 2030, urea produced from green ammonia can be cost-competitive with urea produced from natural gas and even coal with a modest price of carbon and when fossil-fuel price distortions are stripped out.

Efforts to examine coal and fly ash

Fossil fuels have met a large portion of the world's ever-increasing energy demands as technology has progressed. Coal-burning in thermal power plants releases gaseous and particulate pollution into the environment, as explained in previously. During the coal-burning fuel cycle, many constituents are released into the atmosphere. India's thermal power plants account for 65 percent of installed capacity and 70 percent of the country's total energy output. The current installed capacity in India, including power utilities, is roughly 90,000 MW. More than 150 million tonnes of coal are currently consumed by thermal power plants in the United States. By 2001, the ratio of thermal power stations is predicted to rise to 75 percent. As a result of the recent liberalization, several thermal power projects are being planned. It is expected that these capabilities will be completely realized during the next five to 10 years. The ash content of Indian coals has been reported to range from 35% to 55%. In general, the ash component makes up about half of the entire weight. 75 thermal power plants in the country generate more than 60 million tonnes of fly ash per year. [2-3].

Studies on Washability Characteristics of Low-Volatile Indian Coking Coal by Differential Crushing

The effect of differential crushing on liberation characteristics has been studied for a low volatile coking coal of Indian origin through washability studies. Two parameters, namely “Index of Washability” (IW) and “Near Gravity Material Index” (NGMI), are used to describe the ease of washability. The ROM Coal is crushed to four different top sizes namely, 75mm, 25mm, 13mm and 6mm.On the basis of calculated IW it is observed that relative ease of washability increases with decrease in top size. From calculated IW values it may be said that this coal can be economically beneficiated using gravity process after crushing to -6mm size. From the calculated NGMI values, the critical specific gravities have been estimated and the values for crushing to -75 mm, -25mm, -13mm and -6 mm are 1.65, 1.68, 1.53 and 1.58 respectively. These critical specific gravity values suggest the separation at this specific gravity range is most difficult task using gravity methods. From NGMI analysis, it may be said that the NGMI values for coals crushed to -25 mm & -6mm are identical (≈ 0.18) at 17% clean coal ash content. This suggests that with similar degree of difficulty, clean coal of 17% ash can be produced from these two different crushing sizes. In order to increase the yield for the clean coal of 17% ash, the decision on blending these two size coals may need to be taken.

Mineralogical Control on Ash Fusion Temperatures of some High Sulfur Indian coals by oxides generated during combustion

ABSTRACT Four different sulfur-containing coals (from low to high) (A, B, C and D) obtained from three different geographical locations of the North Eastern Region (NER) of India were studied for the control of ash fusion temperature (AFT) by oxides, generated via in-situ process, during coal combustion. The Meghalaya (B and C) and Nagaland (D) coals were found to contain high ash content in comparison to that of Assam coal (A). Meghalaya coals (B and C) were found to be better as they produce ash in greater quantity of acidic components (Al2O3 and SiO2) and lower amount of basic components (Fe, Ca, Mg, Na and K oxides). This results in lower value of slagging and fouling indices of the Meghalaya coals, and hence increases their AFT. X-ray diffraction studies (XRD) and atomic absorption spectroscopy (AAS) were also performed for qualitative mineralogy and elemental analyses. Statistical tools. such as correlation coefficient and principal component analysis (PCA), confirmed that the low-to-medium AFTs of the coal samples are due to the presence of various fluxing agents (such as K, Fe, Mg and Ca). Ternary phase diagram indicates the fact that the Meghalaya coals (B and C) have higher amount of Aℓ2O3 with lower Fe2O3 contents, resulting in increased fusion temperature.

Heat and Humidity Problems in Indian Coal Mines Mass Production Panels and Their Remedies

Heat and Humidity Problems in Indian Coal Mines Mass Production Panels and Their Remedies

Effect of surfactant, ionic strength, mineralogical composition, and surface morphology on zeta potential of bituminous coals of Indian origin

ABSTRACT The variation of zeta potential of high ash Indian coals in the presence of various surface modifying conditions has rarely been studied in depth. The objective of the present investigation was to perform a detailed comparative study on surface zeta potential of two distinct Indian coals that have substantial differences in their ash content and surface chemistry. Detailed characterization studies of the two coals were performed using FTIR, petrography, and proximate and ultimate analyses, which demonstrated that Topa coal was more hydrophobic in comparison to Kulda coal. Electrokinetic measurements at ambient temperatures demonstrated that the zeta potential of both coals was dependent on pH, ionic strength, and type of surfactant. The surface potential of both coals, irrespective of the extent of mineral association, was only affected by cationic surfactant over a prolonged contact time. XRD analysis of the coal ash samples revealed the presence of quartz, hematite, mica, and zeolite as the predominant minerals. In the present study, the inherent and surface chemistry of mineral-rich coals was correlated through the measurements of zeta potential. It was concluded that the variation in mineral matter content does not impact the zeta potential of coal particles significantly.

Indian coal pyrolysis behaviour and kinetics study using covalent bond information

Coal pyrolysis is a critical step of coal thermal conversion, impacting the downstream utilisation of coal, such as combustion and gasification. The understanding of this complex process plays a crucial role to predict the products, operation optimisation and reactor design. Indian coals typically have 25–52% (as received) ash yields. There is little knowledge about the pyrolysis kinetics of Indian high-ash coals, which are widely used in Indian power plants. In this work, five Indian thermal coals were investigated using thermogravimetric analysis (TGA) at heating rates varying from 278 to 773 K/min to provide pyrolysis kinetic data. The common single reaction kinetic model (Friedman) was used to analyse the pyrolysis behaviour of the coals and estimate the kinetic parameters. The activation energies ranged from 428.78 to 520 kJ/mol. Six Gaussian functions were used to analyse the DTG curves, each presenting a group of covalent bonds. The variation of pyrolysis behaviour is highly correlated to the distribution of aliphatic and aromatic carbon structures in the coal. The activation energy of coal pyrolysis can be estimated using the chemical bonds information obtained from the curve-fitting results of the DTG curve.

Seismic site characterization of a few Indian coal ash deposits using multichannel analysis of surface waves

This study presents the outcome of an extensive field experiment undertaken to characterize coal ash deposits in terms of dynamic properties. In-situ shear wave velocity ( V s ) was measured over three hydraulically deposited coal ash deposits (two active ponds and one abandoned pond) situated in the central and southern parts of India. Multichannel analysis of surface waves was performed at twenty-one different locations on the ash deposits and the dyke top to measure the V s profiles along the depth ( z ). V s profiles measured for the abandoned coal ash deposits were greater than those of the active deposits. Moreover, the empirical association of V s profiles from active and abandoned coal ash deposits in India, based on the present study and reported literature, yields a piecewise linear relationship between shear wave velocity and depth. • Shear wave velocity (V s ) values from MASW for three coal ash ponds in India. • Box and whisker plots for inter and intra-site variations in V s profiles. • Comprehensive data on the variation of V s vs. z for all Indian coal ash deposits. • Empirical association between in-situ average shear wave velocity, V s,a vs. z for Indian ashes.

The politics of dispossession and compensation in the eastern Indian coal belt.

Ethnographic studies in sites of land dispossession for large capital projects have revealed the diversity of local political responses to this process, from fierce resistance to compliance. The theoretical challenge, in this context, is to trace the particular factors that affect this politics, and the conditions under which different reactions to dispossession unfold. Drawing on fieldwork in an Adivasi (tribal) village adjacent to an opencast coal mine in Jharkhand, India, this article seeks to contribute to this inquiry. It illustrates how, in a predominantly precarious labour environment, the possibility of formal employment as compensation for expropriated land, and the ways in which such employment enables class mobility, can play a salient role in shaping local political dynamics around dispossession. The analysis shows how, in the community studied, compensatory jobs for dispossession gave rise to new class differentiation and shifts in political relations that have acted to curb potentialities of resistance – precisely in a context in which opposition to dispossession could have otherwise been considered likelier to emerge.

Prediction of Strata Monitoring System in Underground Coal Mines Using IoT

ABSTRACT Underground coal mines are known for being one of the most hazardous sectors due to its working environment. The mine workers are usually prone to many risk factors leading to heavy casualties. As per the statistical records of Directorate General of Mines Safety, roof fall is one of the major causes of accident in Indian underground coal mines. One of the critical contributing factors of such accidents is lack of roof fall prediction system, thereby leading to failure to withdraw or removal of working persons before the actual failure. Real-time monitoring of strata movement and analysing the acquired data for predicting possible roof fall well in advance through an effective intelligent system can certainly pave way in reducing the accidents due to roof fall. The paper presents an integrated strata management system for continuous monitoring of strata behaviour and analysing the data using artificial intelligence for prediction of failure of strata ahead of time. This web-based monitoring system initially sets the customizable threshold values according to the mine conditions followed by continuously monitoring of the strata conditions including triggering an alarm system when the retrieved data crosses the set threshold limit.

A comparative kinetic study between TGA & DSC techniques using model-free and model-based analyses to assess spontaneous combustion propensity of Indian coals

Kinetic study of coal was carried out using simultaneous thermal analysis (STA) technique to assess the spontaneous combustion propensity of coal samples collected from various Indian coalfields having both fiery and non-fiery seams. The kinetic parameters were estimated by using both model-free and model-based analysis for both TGA & DSC data. The model-based method comprises four different consecutive reaction steps, viz. A→B→C→D→E for the spontaneous combustion process and the second reaction step (B→C) were used for this investigation. Chemometric analysis was applied to know the relation between the proximate analysis and activation energy of the samples using model-free and model-based techniques. The activation energy for the second reaction step of the model-based method for both TGA and DSC data showed a good relationship with the standard methods i.e., crossing point temperature (XPT) and Tgign of the samples. It indicates that the activation energy values at the oxidation stage (2nd stage) play a significant role in the spontaneous combustion propensity of coal. The study also reveals that the model-based analysis provided better results in comparison to model-free analysis to assess the spontaneous combustion propensity of coal.

Evaluation of Indian non-coking and semi-coking coals for metallurgical application

ABSTRACT India has a huge reserve of coal belonging to Permian Period. 85% of these coals fall under non-coking category and are being used for power generation. Looking at the depletion of coking coals, there is a huge challenge for the Indian steel industry to manufacture coke using domestic coals. Utilizing Indian non-coking or inferior coals for coking purpose is a challenging task because of its higher ash content and poor rheological properties. These coals are less matured than coking coals and contain higher amount of organic and inorganic inerts. To study the effect of blending Indian thermal coals on coke CSR, eight different coals of varying characteristics have been used for experimentation. To improvise their coking ability and resulting coke strength on carbonization, phenol formaldehyde-based polymer addition has also been tried and tested. In most of the cases, it has been found that CSR got improved because polymer acts as a catalyst and improves the binding behavior and rheological property of the coal blend. Present work suggests that Indian thermal coals can be used up to 10% as one of the component coals in the blend for coke making with polymer addition.

Experimental and computational fluid dynamics simulation of performance analysis of steam generators of boilers

Poor air temperature in modern power plants is one of the main reasons for the increase in unit temperature and the deterioration of boiler performance. The main problem of the air preheater is the leakage of air on the side of the gas flue and thus lead to improper thermal performance. Thehigh ash content in Indian coal also adds to the problems associated with air tube heating. Air preheaters are designed to meet the operational requirements with consideration of the most impact parameters. heat transfer, leakage and pressure reduction. In the current work the performance of the air-conditioning heater is being tested with the help of the computational fluid dynamics (CFD)Fluent 14.0 analysis tool.