High Ash Indian Coal Research Articles

Rheological Characteristics of High Ash Indian Coal with Sodium Dodecyl Sulfate as Additive

Rheological Characteristics of High Ash Indian Coal with Sodium Dodecyl Sulfate as Additive

Separation characteristics of CrossFlow separator for beneficiation of high ash Indian fine coal

ABSTRACT The paper outlines the efforts to reduce the ash content of fine-size (−0.50 mm) high-ash Indian coal in a counter-current teeter bed separator, i.e. a CrossFlow separator. The tests conducted in the CrossFlow separator by varying the water injection flow rate and bed pressure reveal that an ash reduction of about 4.71% (from 34.94% to 30.23%) could be possible for −0.50 mm size coal. However, when the separation was analyzed by splitting it as coarser coal (−0.50 + 0.075 mm) and fines (−0.075 mm) independently, an appreciable reduction in ash content of about 11.0% was noticed in coarse fractions. In comparison, only a marginal ash reduction was possible for the finer fraction (−0.075 mm). Further, the size and density-based partition curves were plotted to understand and depict the separation behavior of the coarse fraction (−0.50 + 0.075 mm). The present investigation concluded that both size and density effects prevail in separating −0.50 + 0.075 mm coarse coal, while the separation fines below 0.075 mm are influenced by hydraulic entrainment. The effectiveness of separation of coarser and finer fractions has been evaluated by “Separation Efficiency.” Further, unified characteristic partition curves have been plotted to establish the prevalence of size and density effects in the CrossFlow separator and mathematically modeled.

Studies on increased utilization of high-ash Indian coal in coke-making

ABSTRACT Due to low-ash coking coal scarcity, India depends on high-cost imported coal for coke making. The present work aims to increase the Indian coal input in the original coal blend for coke making. One typical Indian high-ash and one imported low-ash coal were used as reference materials, presently used in coal blend for coke production in IISCO Steel Plant Burnpur (ISP), West Bengal, India. Coal samples were ground, changing various parameters. The ash distribution in different particle sizes was evaluated. It is observed that decreasing the particle size up to −88 µs can reduce ash content from (18–23%) to (12–14%), which is generally considered suitable for the blended coal mixture used for coke making in the coke-oven battery in ISP. Reduced ash containing fraction of high- ash coal was utilized to evaluate the dilatation behavior and economics of the coking process by considering blending with different percentages of beneficiated Indian coal. From the behavioral study, it was observed that 20% blending would be economical for coke making without hampering the original blend property. The improved dilatation behavior was observed by incorporating 20% dry beneficiated Indian coal in the original blend. The CRI, CSR, and Micum index properties are identical with the normal blend and within the acceptable limit.

Waste heat utilization using organic rankine cycle from a pressurized pulverized combined cycle power plant

Power plants release a massive amount of waste heat at very low temperatures. Posing a challenge for efficient conversion into useful work through conventional methods. By selecting appropriate working fluids, low-grade power cycles can solve this problem by converting waste heat to electricity. The present work dealt with waste heat utilization using the Organic Rankine Cycle (ORC) from a 400 MWe coal based supercritical Pressurized Pulverized Combined Cycle (PPCC). The working fluid for the ORC is the refrigerant R245fa. High-ash (HA) Indian coal and low-ash (LA) South African coal are used as fuel to assess the plant’s ability to produce electricity under ambient conditions in India. The simulation flowsheet program “Cycle-Tempo” models and simulates different plant layouts. The thermodynamic assessment unveiled that the standalone plant has energy and exergy efficiencies of 43.46% and 39.87% for HA & 45.42% and 43.84% for LA, respectively. According to this study, the proposed plant has energy and exergy efficiencies of 44.63% and 40.94% for HA & 46.69% and 45.07% for LA, respectively. Moreover, using ORC, the waste heat generates additional electricity of 9.38 MWe, with an energy efficiency of 12.92% and exergy efficiency of 34.63%.

Effect of Mean Specific Gravity on Combustion Characteristics of Selected High Ash Indian Coal

Effect of Mean Specific Gravity on Combustion Characteristics of Selected High Ash Indian Coal

Synergistic effect of coal and biomass gasification and organo-inorganic elemental impact on gasification performance and product gas

The current study demonstrates the synergistic effect of co-gasification of high-ash Indian coal and biomass (press mud and sawdust) blends in varying proportions in a pilot-scale bubbling fluidized bed gasifier (BFBG) with a capacity of 20 kg/h. The effect of blending on product gas yield, composition and heating value, carbon conversion, and cold gas efficiency was critically analyzed. Mineralogical transformations and catalytic effects were investigated during co-gasification, wherein minerals in ash residue, such as hematite, sylvite, chlorite, K-feldspar, CaO, and MgO, showed a catalytic role in co-gasification, increasing the product gas compositions, and reverse the trend for kaolinite and phosphate minerals. Blending coal with biomass enhances the porosity and reactivity of blends, surface morphology, gasification performance, and product gas yield. So, high ash coal and biomass are suitable for gasification. The high ash coal gasification comprises the volumetric product gas composition (%) of CO (9.79), CO2 (8.75), H2(13.6), and CH4(1.12) with the maximum blends (40%) of biomass, the volumetric composition (%) is enhanced comprising CO (17.71), CO2 (14.8), H2(19.9) and CH4(2.05) for press mud blend, and CO(15.84), CO2(14.2), H2(18.3) and CH4(2.29) for sawdust blend, respectively, and HHV increases from 3.42 (MJ/Nm3) to 5.59(MJ/Nm3).

Rapid Estimation of Sulfur Content in High-Ash Indian Coal Using Mid-Infrared FTIR Data

High-ash Indian coals are primarily used as thermal coal in power plants and industries. Due to the presence of sulfur in thermal coal, flue gas is a major environmental concern. Conventional methods (Ultimate Analysis of Coal) for sulfur content estimation are time-consuming, relatively costly, and destructive. In this study, Fourier-transform infrared (FTIR) spectroscopy has emerged as a promising alternative method for the rapid and nondestructive analysis of the sulfur content in coal. In the present study, the actual sulfur content in the coal samples was determined using Ultimate Analysis (CHNS analyzer). In contrast, mid-infrared FTIR spectroscopic data (4000–400 cm−1) were used to analyze the functional groups related to sulfur or its compounds in the coal samples to predict the sulfur content. A comparison of sulfur estimated using a CHNS analyzer and predicted using mid-infrared spectroscopy (FTIR) data shows that it can accurately predict sulfur content in high-ash Indian coals using the piecewise linear regression method (Quasi-Newton, QN). The proposed FTIR-based sulfur prediction model showed a coefficient of determination (R2) of up to 0.93, where the total no. of samples (Coal + KBr pellets, n) was 126 (using 17:1 split, K-fold cross validation). The root-mean-square error (RMSE, wt.%) is 0.0035, mean bias error (MBE, wt.%) is −0.0003, MBE (%) is 3.31% and mean absolute error (MAE, wt.%) is 0.0020. The two-tailed t-test and F-test for mean and variance indicated no significant difference between the pair of values of observed sulfur (SCHNS, wt.%) using CHNS data and the model predicted sulfur (SFTIR, wt.%) using FTIR data. The prediction model using mid-infrared FTIR spectroscopy data and the Quasi-Newton method with a breakpoint and loss function performs well for coal samples from the Johilla Coalfield, Umaria. Thus, it can be a valuable tool for analyzing sulfur in other ash-rich coals from various basins worldwide.

Assessment of combustion characteristics of high ash Indian coal, petroleum coke and their blends for cement industry using TGA

This work investigates the combustion analysis of coal, petroleum coke and their blends. Coal and petroleum coke were characterized by proximate analysis, ultimate analysis, gross calorific value determination and ash analysis. Combustion performance of parent fuels and their blends were evaluated by thermogravimetric analysis followed by the analysis of different characteristics parameters, namely ignition temperature, peak temperature, burnout temperature and combustion efficiency. Results signify that petroleum coke has poor combustion characteristics compared to coal. After the rise in petroleum coke from 10 to 50 mass %, ignition temperature reduced from 413 to 385 °C, while insignificant variations occurred in peak temperature and burnout temperature. Such observations show natural reduction in ignition characteristics without significant modification in coal's burning profile. Combustion efficiency at 450 °C reduced from 46.18% to 34.77% as petroleum coke increased from 10 to 50 mass %, signifying decline in the combustion properties of coal. Kinetic analysis shows that petroleum coke has the maximum activation energy (182.11 kJ/mol) than coal (84.84 kJ/mol). Analysis of changes in enthalpy, Gibbs free energy and entropy inferred that individual combustion of both coal and petroleum coke is difficult, while blends have improved combustion characteristics than petroleum coke.

CO2 based co-gasification of printed circuit board with high ash coal

Electronic wastes are accumulated in the environment due to their non-degradability nature, which makes them unsuitable for landfills. Printed circuit board (PCB) is one of the e-wastes significantly occupying the generated wastes. To utilize them efficiently, in the present study, PCB is thermally treated under N2 and CO2 conditions by pyrolysis and gasification processes at various temperatures. A maximum tar yield of 7.46% is obtained during PCB pyrolysis at 500 °C with a tar calorific value of 31.28 MJ/kg. CO2 gasification of PCB mixture at 1000 °C achieved the highest conversion of 97.6% resulting in a cold gas efficiency (CGE) of 91.9% and exergy efficiency of 82.9%. Further, high ash Indian coal is co-gasified with PCB mixture. It is found that the addition of PCB mixture, PCB resin, and PCB plastic in a 4:1 ratio (HAC: PCB) with HAC increased the CGE by 6.81%, 4.26%, and 2.3%, respectively. Further, the BET analyses of the co-gasification residue showed the generation of surface area as high as 186 m2/g and therefore, it can be suitable as a catalyst for cracking reactions. Further, the residue contains CaCO3, TiO2, and SnO2, which are potential additives in the concrete material for the construction of buildings.

Characteristics of the HGI Fractions of the Indian Coal Blended with Imported Coals

The blends of a high ash Indian coal with three coals of different foreign origins -Australia, Russia and Indonesia weresubjected to HGI testing as per ASTM D 409 and the resulted fractions obtained in the coarser and finer portions of ASTM200 mesh (75 microns) were assessed for their characteristics in respect of proximate and ultimate parameters, alphaquartz and combustion reactivity. The similar studies were also carried out for the parent coals. HGI values were foundadditive in case of Indian-Indonesian coal blends and the same was found non-additive in respect of Indian-Russian andIndian-Australian coal blends. Considerable variation in properties was observed in the coarser and finer fractions of theASTM 200 mesh for parent Indian and Indonesian coals compared to parent Australian and Russian coals. This indicatesthe disproportion of the coals and coal blends particles during the sieving process after subjecting to HGI test. The variationof alpha quartz content in the coarser and finer fractions indicate that there is a segregation of free minerals in the coarserand finer fractions. The conversion plots obtained through TGA for the coarser and finer fractions indicate that there is nomaceral segregation.

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.

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.

CARBON-BASED RAW MATERIALS PLAY KEY ROLES IN TECHNOLOGY OF THE 21ST CENTURY: INDIAN CASE STUDIES

Coal is a vital carbon-based raw material which is used in the production of various advanced nanomaterials. This particularly holds true for the relevant research and development trends in India. New more environmentally friendly processes are under development with respect to metallurgical coke making and quality enhancement of high-ash Indian coal. Compared with chemical and physical methods, beneficiation of high-ash coal and its combustion by-products with organic liquids (various natural oils) are much more superior in terms of costs, efficiency, and environmental implications. Nanodiamonds have emerged as a key platform for nanoscience and nanotechnology developments. Indian scientists have applied eco-friendly and cost-effective ultrasonic assisted wet-chemical method to low-quality NE Indian coal and the resulting nanodiamond particles could have a wide range of applications in the field of microelectronics, optoelectronics, and biosensing. Also, Indian scientists have been working on ultrasonic-assisted chemical synthesis of activated carbon from low-quality subbituminous coal and its preliminary evaluation towards supercapacitor applications. This article shows that coal is a versatile and valuable raw material which should be saved for future generations at all costs.

Effect of rice husk and petroleum coke blending on combustion characteristics of high ash Indian coals

Effect of rice husk and petroleum coke blending on combustion characteristics of high ash Indian coals

CO2 based synergistic reaction effects with energy and exergy (2E) analysis of high density polyethylene with high ash bituminous coal for syngas production

A larger accumulation of medical waste is one of the major environmental issues due to the COVID-19 pandemic situation. The segregation and use of waste plastics from medical waste as a source of fuel for syngas production are highly beneficial. In packaging plastics, high density polyethylene (HDPE) occupies 20% of the total waste plastics. Hence, the conversion of HDPE into syngas is essential for waste reduction and energy production. Further, Indian coals possess high ash content (20–40%) and hence they produce a low calorific value gas on gasification. Hence, the co-gasification of these coals with suitable fuels such as HDPE can raise the heating value of syngas. In this context, HDPE is co-gasified with a high ash Indian coal using CO2 as the gasification agent for syngas production. Co-pyrolysis and co-gasification behavior of HDPE with high ash coal (HAC) under CO2 atmosphere are analyzed by using a fixed bed reactor and a thermogravimetric analyzer. Unlike reported in the recent literature, the present study showed that a high quality syngas can be obtained from the co-gasification process (1000 °C) with the heating value of 22 MJ/m3 using CO2 as the gasification agent. The chemical reactivity between CO2 gas, coal volatiles, and ethylene molecules significantly altered the surface morphology of char, which becomes highly porous making suitable for Boudouard reaction. On the surface of char, ester, and acid functional groups are formed. The co-feeding conditions raised the cold gas efficiency by 51% and the specific exergy of syngas by seven times that of HAC.

Effect of rice husk blending on combustion characteristics of high ash Indian coal analyzed in TGA

ABSTRACT Present work reports the effects of rice husk (RH) blending on combustion characteristics of high ash Indian coal. Combustion experiments were carried out using the thermogravimetric analyzer (TGA). Combustion performance of coal, RH, and coal-RH blends were assessed through identification of ignition temperature (TI), peak temperature (TP), burnout temperature (TC) along with ignition index (IIX), combustion characteristics index (CIX), burnout index (BIX), heat intensity index (HIX), activation energy (AE), and thermodynamic parameters (, ΔG, and ΔS) analysis. Experimental results show that with the increase in RH mass in coal up to 50%, TI decreased from 418 to 263°C, TP decreased from 468 to 450°C, TC decreased from 499 to 490°C, and AE reduced from 84.84 to 72.42 kJ/mol, inferring substantial enhancement in coal combustion performance. , ΔG, and ΔS analysis showed that with 50% RH in coal reduced from 78.66 to 67.11 kJ/mol, ΔG improved from 147.62 to 57.66 kJ/mol, ΔS varied from −92.48 to 15.99 J/mol.K, concluding blending of RH eases the combustion.

Slurryability and flowability of coal water slurry: Effect of particle size distribution

As a part of clean coal technology, the coal water slurry has a popular application in the conventional and new thermal power stations. The hydrotransport is now-a-days a preferred method, due to its low specific energy consumption and non-polluting nature. The lignites and high ash coals, available in abundance, show poor slurryability, thereby making the process unsustainable. This study proposes and demonstrates how a careful selection particle size distribution can help in the improvement of the slurry stability, rheology and flow characteristics. To achieve this objective, 3 different size ranges of pre-pulverized coal are considered and blended to get a total of 8 blended samples. The influx concentration of a given sample ranges in 10–60%. The influx velocity of mixture lies in the range of 0.25–1.25 m/s, through a pipeline of 100 mm diameter. The parameters viz. Settling characteristics, apparent viscosity, headloss and specific enthalpy consumption are evaluated to choose the best particle size distribution of the coal sample. The 30% fraction of >53 μm and <75 μm particles and 20% fraction of >75 μm and <106 μm are found to be optimum for high stability, low viscosity and specific enthalpy consumption. This study provides a simple solution to enhance the flow characteristics of a high ash Indian coal.

Investigation of co-pyrolysis characteristics of high-ash Indian coal and rice husk

This study investigates the non-isothermal pyrolysis characteristics of a low-grade, high ash Indian coal, and rice husk using a thermogravimetric analyzer (TGA). A series of thermo-gravimetric experiments are conducted to examine the effects of coal and biomass blending on their thermal degradation behavior and synergetic effects in the nitrogen atmosphere. The thermo-gravimetric (TG) curves show two distinct tips where the larger tip is obtained for biomass as compared to the coal. The thermogravimetric study does not demonstrate any significant synergetic interaction between the biomass and high ash coal in the blends, and the additive rule describes the behavior of their combined pyrolysis. The activation energy and preexponential factor for coal and biomass are calculated based on the TGA data using the Friedman method. the corresponding calculated mean activation energy values for the biomass and Indian low-rank coal were found to be 203.463 KJ/mol, and 66.97 KJ/mol respectively.

COMPARATIVE STUDY OF VARIOUS APPROACHES IN ANALYSIS OF TGA DATA OF DEVOLATILIZATION OF HIGH ASH INDIAN COAL

ABSTRACT Thermo gravimetric analysis (TGA) has been regularly employed for the estimation of devolatilization rates and measurement of char reactivity of coal. In general, TGA studies may be classified as isothermal or non-isothermal. In the first case temperature of the sample is kept constant whereas in case of latter the rate of temperature increase is kept constant. The current research work deals with the non-isothermal TGA study and kinetic analysis of three typical pulverized high-ash Indian coal samples each weighing around 15 mg. TGA experiments were carried out for four different heating rates (5, 10, 15, 20 K/min) and weight loss curves have been obtained. Out of the various methods proposed to analyze the TGA data, the following methods have been evaluated i) Friedman method, ii) Flynn-Wall-Ozawa method (FWO), iii) Kissinger method, iv) Kissinger-Akahira-Sunose (KAS) method, and v) Miura-Maki method. Activation energy and frequency factor to be used in the Arrhenius equation is calculated using all the above methods. The most accurate method for analyzing TGA data for high-ash Indian coal is FWO as per studies carried out in this research work.

Combustion characteristics of high ash Indian coal, wheat straw, wheat husk and their blends

This work presents the combustion studies of high ash coal, wheat straw (WS), wheat husk (WH) and their blends to enhance the combustion performance of high ash coal. Coal, WS and WH were characterized by proximate analysis, ultimate analysis and gross calorific value (GCV) determination. Combustion performance of individual fuel and their blends were assessed by thermogravimetric (TGA) investigation followed by the study of various burning profile parameters such as ignition temperature (Ti), peak temperature (TP), burnout temperature (Tb), ignition index (IIX), combustion characteristics index (CIX) and burnout index (BIX). Experimental results show that coal has poor combustion characteristics compared to WS and WH. After the addition of 20% WS with coal Ti reduces from 383 °C to 257 °C, TP reduces from 452 °C to 287 °C, Tb reduces from 509 °C to 507 °C. Combustion performance indices analysis inferred that after the addition of 20% WH with coal, IIX improved from 2.81 to 5.14 mass2/min2OC3 and CIX improved from 3.58 to 8.11 mass/min2 °C3. Activation energy (AE) analysis shows that coal having higher AE (82.13 kJ/mol) compared to WS (57.97 kJ/mol) and WH (56.56 kJ/mol). Based on ΔH, ΔG and ΔS analysis it was observed that individual combustion of coal is difficult compared to WS and WH combustion, whereas blending of WS/WH makes the combustion process significantly favorable.