Thar Coal Research Articles

Effect of Thar Coal Fly Ash on Compressive andTensile Strength of Concrete

Effect of Thar Coal Fly Ash on Compressive andTensile Strength of Concrete

Analyzing the combustion characteristics of Thar coal block XI: A comprehensive study

Coal is a key energy resource in the world that is available at low cost and the high energy content in coal makes it a fuel of choice in many developed and developing countries. Regardless of massive reserves, Thar coal of Pakistan is low-rank lignite coal with high moisture contents and has very limited use. The proximate analysis, ultimate analysis and X-ray diffractometry analysis were performed to investigate the combustion characteristics, morphological and mineral characteristics of Thar coal block XI. Thar coal samples in this study are characterized as low-rank lignite coal. The proximate analysis showed a significant difference in moisture content, volatile content, fixed carbon content and ash residue. The ultimate analysis provided the details of elemental contents (Carbon, Hydrogen, Nitrogen and Sulfer) in coal. The combustion characteristics such as combustion performance of lignite at high temperatures (950 °C) was investigated in thermogravimeter and the results showed the variations in the ignition temperature, burnout tempearature, combustion index and burnout index. The marphological characteristic were determined by X-ray diffraction. The mineral congregations, ash yields, major and minor elements (SiO2, Al2O3, CaO,MgO, Fe2O3) varied significantly in the coal. These analyses integrate various results for assessing major monitoring parameters of coal reactivity, its temperature ranges and combustion products.

Impact of coal quality on power plant and environment: assessment of physiochemical and ash composition of Thar coal from Pakistan

Impact of coal quality on power plant and environment: assessment of physiochemical and ash composition of Thar coal from Pakistan

Artificial intelligence model of fuel blendings as a step toward the zero emissions optimization of a 660 MWe supercritical power plant performance

AbstractAccurately predicting fuel blends' lower heating values (LHV) is crucial for optimizing a power plant. In this paper, we employ multiple artificial intelligence (AI) and machine learning‐based models for predicting the LHV of various fuel blends. Coal of two different ranks and two types of biomass is used in this study. One was the South African imported bituminous coal, and the other was lignite thar coal extracted from the Thar Coal Block‐2 mine by Sind Engro Coal Mining Company, Pakistan. Two types of biomass, that is, sugarcane bagasse and rice husk, were obtained locally from a sugar mill and rice mill located in the vicinity of Sahiwal, Punjab. Bituminous coal mixture with other coal types and both types of biomass are used with 10%, 20%, 30%, 40%, and 50% weight fractions, respectively. The calculation and model development procedure resulted in 91 different AI‐based models. The best is the Ridge Regressor, a high‐level end‐to‐end approach for fitting the model. The model can predict the LHV of the bituminous coal with lignite and biomass under a vast share of fuel blends.

Chemical association and combustion behaviour of cadmium in coal of different mining fields using sequential and single step extraction methods

ABSTRACT This work sought to conduct the chemical association of a toxic metal (cadmium) in coal samples of various origins in Pakistan. For that purpose, a sequential extraction scheme recommended by the Community Bureau of Reference (BCR) has been carried out to know the chemical fractionation of Cd in different coal samples. Simultaneously a time saving vortex-assisted single-step extraction (VA-SSE) via the same experimental parameters conditions used in each fraction steps of BCR sequential extraction procedure (BCR-SE). The coal samples were collected from Thar coal (TCF) and Lakhra coal fields (LCF) of Sindh, Pakistan. The validity of BCR-SE and VA-SSE were checked by applying spiking standard addition procedure on real coal samples. The BCR-SE and VA-SSE were completed in 51 h and 1.0–2.0 min, respectively. In second phase determined the combustion behaviour of Cd or/amount of Cd in coal samples volatilise after heating in an electric furnace in laboratory at three temperature interim (200°C, 400°C and 900°C). The coal ash obtained at 900°C was put to three step sequential extraction method. The evaluated result showed that the total values of Cd in coal samples of block II of Thar coal field (TCF), Site I and Site II of Lakhra coal field (LCF) were found in the range of 3.42–4.43, 2.02–2.82 and 2.91–3.92 mg/kg, correspondingly. The final result indicated that the major chemical fraction of Cd was bound with organic phase of coal samples of both origins (about 40%). The evaluated data showed that 60–71% of Cd in coal samples was found in first three fractions, whilst about 29–40% of Cd was observed in residual. The extracted Cd concentrations in various chemical fractions of coal samples obtained through VA-SSE were 1.6–2.6%, higher than those values gained via BCR-SE (p < 0.04). The resulted data indicated that, after burning of coal samples at 900°C, about 63–69% of total Cd in coal samples of both mining areas was found in residual ash, while 31–34% was vaporised/volatilised out into the atmosphere.

Cleaning of Thar coal by froth flotation and water washing

The demand for a constant supply of energy is increasing day by day. To meet these increasing demands the natural resources must be utilized smartly. Coal can be a promising fuel due to its large reserves available in Pakistan. About 175 billion tons of coal reserves are found in Thar region of Sindh province. The major issue is the pre-processing cleaning of coal after it is mined out. A number of methods have been adopted to clean coal.&#x0D; Presently, cleaning of Thar coal was carried out using froth flotation and water washing techniques. Three different particle sizes (-60#, -100# and -150#) were employed to study the effect of froth flotation on ash and sulfur reduction. Experiments were carried out in laboratory flotation cell and beakers under different set of conditions (i.e., flotation with and without collector and frother and by simple water washing). Kerosene oil was used as a collector and pine oil as a frother. Characterization of raw and treated Thar coal samples was carried out by ASTM standards. The results exhibited an inverse relationship of particle size towards efficiency of the cleaning process; thus, the optimal combustible recovery was attained at -150# particle size. Furthermore, FTIR results disclosed the presence of aromatic and aliphatic structure in treated coal samples. Thermo-gravimetric analysis was also made to determine the weight loss in raw and treated samples and observed increased combustion efficiency and reactivity of Coal.

Emissions Reduction by Combustion Modeling in the Riser of Fluidized Bed Combustor for Thar Coal Pakistan

Pakistan has experienced a protracted electricity shortage for the past few years. However, despite Pakistan’s abundant coal deposits, modern coal combustion technology is still required to reduce emissions. Pakistan is struggling to utilize its energy resources and currently experiencing an electrical shortage of more than 8000 MW. The research study models the combustion performance in a fluidized bed riser using ANSYS FLUENT software to understand the combustion behavior of low-rank Thar coal. A simple circulating fluidized bed (CFB) combustion riser was modeled for computational fluid dynamics (CFD) to study the hydrodynamics of gas-solid flow in a circulating fluidized bed riser to reduce emissions and operating costs. Three different types of risers/combustors geometries were used center flow, counter flow, and parallel flow. The CFD model for the solids segment with a k-e turbulence model and the viscosity of static particles in the gas segment both showed excellent mixing performance. According to the FLUENT data, the riser/combustor maximum temperature is around 1400 K or 1130 o C at the primary burning sector in the bed center. According to velocity contours, the greatest velocity in the center-oriented riser/combustor peaks at 3.3 m/s. The CO and CO2 both mass fraction counters show maximum concentration in the center geometry, whereas lower CO concentration is found in parallel geometry. The lowest level of NOx is established in the parallel geometry at around 15 ppm, whereas the counter contours establish the maximum level of NOx at about 31 ppm. Circulating Fluidized Bed Combustor is found to be the most advantageous and effective technology for producing power from Thar lignite coal and reducing emissions.

Conversion of Coal-Biomass into Diesel by Using Aspen Plus

Taking the importance of Pakistan’s dire need for energy breakthrough, in this paper, we explore how the country’s vast estimated reserves of 175 billion tons of Thar coal is a useful source for the clean and efficient production of good quality liquid fuel. Coal to liquid (CTL) technology has gathered increasing attention among many countries with a sufficient volume of coal reserves, and this technology can also be implemented in Pakistan, which in result can also reduce harmful greenhouse gas (GHG) emissions in the environment. In this study, the Fischer Tropsch Synthesis (FT) liquefaction method was used, and the reactor design, chemical reactions, syngas ratio fraction, and Anderson-Schulz-Flory and Langmuir model were all obtained from the Aspen Plus simulation. The results showed that, at the optimum syngas flow rate of 9 Kg/s, the FT model produced diesel fuel at 0.00134 Kg/s. Per this calculation, the massive amount of Thar coal reserves can be transformed into 123.22 million barrels of diesel. The design of the reactor is very critical, and, in this study, it was prioritized to design a reactor that produces liquid fuel only of composition C12+; during the production of liquid fuel, the quantity of methane is not high; and it can still be further reduced on optimized conditions. On the other hand, CO2 gas, which is a sole contributor of GHG emissions, was also reduced by up to 98%.

Exploitation of Thar coal field for power generation in Pakistan: A way forward to sustainable energy future

Thar desert is located in south-east Pakistan carries 175 billion tons of coal and is the biggest coalfield in Asia. In this paper mathematical framework is developed for the accurate estimation of power production from the available Thar coal capacity. Annual TWh possible energy production the period 2020 to 2040 followed by detailed analysis of capacity factor and Maximizing the share percentage of coal in total energy mix at least 40% by 2040 is presented. The findings reveal that Thar coal has the capability of producing 100,000 MW power up to the next 250 years. The energy generation for the years 2020, 2032, and 2040 is calculated 744 TWh per year, 700 TWh per year, and 665 TWh per year respectively and it produces negligible negative impacts on the environment. The long-term energy planning presented in this paper would attract foreign investment and Pakistan's energy needs would be fulfilled for sustainable development of the country.

Desulfurization of thar lignite by oxidative alkali leaching under pressure

ABSTRACT In this research work, thar coal was treated with NaOH solution in dissolved oxygen with different reaction parameters in an isothermal reactor. All three types of sulfur were removed from coal through oxidative alkali leaching under pressure. About 90% pyretic sulfur, 78% organic sulfur and 50% sulfate sulfur were removed, and more than 82% of total sulfur removal was achieved. Effects of various reaction parameters were observed, it was investigated that reaction time, agitation speed and partial pressure of oxygen have positive effects on the rate of desulfurization. Whereas desulfurization was increased with increase in reaction temperature and alkali concentration till optimum value as 120°C for temperature and 2.5 Molarity of NaOH solution for alkali concentration . While desulfurization was decreased with further increase in values of temperature and alkali concentration. The rate of desulfurization was observed maximum with minimum particle size of 40 µm. An Optimized reaction was performed reaction time 120°C oxygen partial pressure 200 psi, particle size 40 µm, NaOH concetration was 0.25 Molarity, reaction time was 3 hours agitation speed was 2000 rpm, after getting the optimum values of all reaction parameters. Processed and raw thar coal was characterized with Thermogravimetric Analysis (TGA) and Testo smoke number to investigate the combustion behavior of processed coal. It was observed that the combustion properties of processed coal were improved than that of raw coal and black smoke in processed coal was reduced.

Investigating Compatible Drying Technique for Safe Utilization of Thar Coal, Pakistan

ABSTRACT To enhance the combustion efficiency of high moist coal, it is important to reduce its moisture contents. For reduction of moisture contents, the selection of efficient and low-cost drying technique based on the coal characteristics is helpful to convert the high moist coal to good quality fuel. A total of 18 Thar coal (Pakistan) samples were crushed and sieved at following size fractions (355, 500, 710 µm). These samples were dried using different techniques, namely, solar-drying, hot air-drying, oven-drying, microwave oven-drying, and flue gases drying. The morphological, physical, and chemical changes were investigated for the effectiveness of different techniques to make the Thar coal as a value-added fuel. The applied drying techniques showed a significant reduction in moisture contents from the Thar coal samples (38.11 to 7.78%). However, the flue gases drying and air-drying techniques showed highest reduction in moisture content (29–31%). Similarly, 35% increase in heating value (HV) J/kg was observed in case of flue gases drying technique. These results indicated that the flue gases and air-drying techniques may be used to reduce the moisture contents and enhance the HV of high moist Thar coal that can be used as value-added fuel in the country.

Characterization of humic acids produced from fungal liquefaction of low-grade Thar coal

Fungal liquefaction of coal is a promising technology to convert low rank coal into value-added products such as humic acids (HAs) that are extensively used as fertilizer. Use of Pakistani Thar lignite for humic acid extraction can promote agriculture industry in Pakistan. In this study, fifty-five fungal strains were isolated from Thar lignite and screened for their lignite solubilization efficiency. Isolates M13 and MI exhibited highest capacity for lignite solubilization and HA was extracted with 67.4 ± 4.3 percent (w/w) yield. Elemental analysis showed increased nitrogen (0.72–1.39 percent) and oxygen (41.7–48 percent), and decreased carbon (51.8–46.1 percent) and sulphur (1.18–0.73 percent) contents in bio-extracted HA (bHA) compared to chemically extracted HA (cHA). UV/Vis spectroscopy showed increased E4/E6 value from 5.6 ± 0.39 (cHA) to 6.28 ± 0.35 (bHA) indicating reduced molecular mass and aromaticity and increased bioactivity of molecule. FTIR analysis also confirmed these results. HPLC analysis of bHA and cHA showed typical choromatogram of humic acids. Enzyme activity staining indicated the presence of fungal cellulase and xylanase on SDS-PAGE gel. The degradation of lignite macromolecules by lignin degrading fungi is a complex process dependent on alkaline substances, chelators, surfactants and extracellular fungal enzymes.

Thar Desert and its Natural Resources: A Case Study of the District Tharparkar in Sindh Province of Pakistan

The research study aims to display natural resources of Thar Desert area ofdistrict Tharparkar in Sindh. It is being studied over the years that DistrictTharparkar is totaled as a richest district in natural resources, such as coal,granite, salt mines, china clay, livestock, range land forest and mushrooms.The topography of the District 99% area covered in the desert which is knownas the part of Thar Desert. The Thar Desert existed into two countriesPakistan and India. The discovery of Thar Coal Reserves is one of thesignificant developments in the history of Sindh province of Pakistan whichplaced country at 7th among world top 12 richest coal reserves countries dueto its economic worth. On the basis of the previous studies; it is expected thatThar coal reserves having the potential to solve the energy crisis of Pakistan.The availability of granite is 26.05 billion tons found into 8 to 10 differentcolors in the area of Nagarparkar. Moreover, China clay extracted at 12 to 14different locations and around 2000 people employed in the different fields.Thar Desert of Pakistan has around 120 salt lakes and around 400 laborerswere employed to harvest salt. The Rangeland forests in the desert area of thedistrict represents the main source of livelihood is livestock and the areas arehighlighted the most densely populated in livestock in Sindh province ofPakistan.

Physiochemical Assessment of Pakistani Thar Coal, A Solution for Sustainable Energy Crises and Reduced Environmental Impacts

Physiochemical Assessment of Pakistani Thar Coal, A Solution for Sustainable Energy Crises and Reduced Environmental Impacts

Techno-economic evaluation of different operating scenarios for indigenous and imported coal blends and biomass co-firing on supercritical coal fired power plant performance

Pakistan has enormous coal and biomass resources, however, it imports coal from other parts of the world. Whereas, utilization of indigenous coal and biomass may be beneficial for the economy and local energy security. Hence, this study focuses on the likely effects of using coal blends and biomass co-firing with indigenous and imported coal on the performance of a supercritical power plant. A coal fired power plant is modeled using Aspen plus. Three different case studies are considered, which are; constant heat input (CHI), constant fuel input (CFI), and constant Reynold number (CRN). Conclusively, coal blending has resulted in reduced emissions than the use of low rank coal. Further, biomass co-firing has shown reduced emissions. For the CHI case, efficiency remains the same for all fuels. The highest efficiency in the CFI case is for South African coal and the lowest is for biomass. In the CRN case, South African coal has maximum efficiency while Thar coal has the minimum efficiency. Moreover, economic analysis of this study proposes that native resources must be used, provided the technical issues have resolved. Therefore, this study resulted in the comparison and applicability of different coal blends and renewable biomass fuel in a coal fired power plant.

Kinetic modeling of gasification reactions of CO2 and H2O for Thar lignite char at elevated pressures

Gasification reactions of Thar coal chars with CO2 and H2O have been investigated, using pressurized thermo-gravimetric analyzer (PTGA). A quartz fixed-bed reactor was used to prepare coal char at 900 °C with a nitrogen environment. Dynamic heating segments were maintained with a constant heating rate during all experiments. The temperature was raised from room temperature to 1000 °C, at different pressures 1 atm., 5 atm., and 10 atm. using pure reacting gases (CO2 and H2O). The weight loss data obtained from PTGA results were used to study the kinetic behavior of Thar lignite char for gasification reactions with CO2 and H2O as gasifying reacting species. It was observed that gasification reactions of char with reacting gas CO2 and char with reacting gas steam (H2O) initiated at 750 °C and completed after reaching 950 °C, at atmospheric pressure, but the occurrence of reactions was slightly delayed at high pressures. Volumetric Model and Grain Model were used to develop a kinetic model for Thar lignite. The direct plot and integral methods were used to calculate Arrhenius parameters such as the pre-exponential factor (A) and activation energy (E). An increase of A and E was also observed in increasing pressures. The activation energy (E) was investigated from 244.64 to 317.6 kJ/mol at atmospheric pressure; whereas, it is lying in the range of 286.13–356.67 kJ/mol at a pressure of 10 atm.

Activation of natural coal for selective preconcentration of Pb(II) ions prior to its trace determination in aqueous samples by flame atomic absorption spectrometer

Abstract Natural coal was collected from Thar coal field, block IX in Province Sindh, Pakistan. The Thar coal was modified to Activated Thar Coal Adsorbent (ATCA) by reacting with concentrated H2SO4, which enhanced its porosity by dehydration as concentrated H2SO4 is strongly dehydration agent. The surface oxidation of coal was carried out by refluxing in concentrated HNO3. The ATCA was subjected to FT-IR spectrometer for characterization, which revealed the presence of C O and COOH moieties onto its surface. The ATCA was packed in column for adsorption of Pb(II) ions and recovered ≥95.6% with relative error ≤4.4% and RSD ≤3.7% at pH 7.0, ATCA dosage 400 mg, sample volume 400 mL (flow rate of 2.0 mL min−1) and eluent solution 5.0 mL of 0.5 mol L−1 HCl (flow rate of 1.0 mL min−1). LOD (0.03 μg L−1) and LOQ (0.11 μg L−1) of method were calculated followed by blank recording (n = 15) with preconcentration factor (PF) of 80. A linear response was observed with regression equation of y = 0.0934x + 0.0411 and R2 = 0.99 for concentration range of 0.5–5.0 mg L−1 (before preconcentration). Similarly, a linear response was also observed with regression equation of y = 7.4358x + 0.0429 and R2 = 0.99 for concentration range of 0.005–0.050 mg L−1 (after preconcentration). Breakthrough curve was plotted for obtaining total saturation capacity (152.5 mg g−1) of ATCA for adsorption of Pb(II) ions. The method worked well on real water samples with recovery ≥92 ± 4.5% of Pb(II) ions.

Investigation of Performance for Entrained Flow Gasifier Through Simulations

Pakistan has proven huge coal reserves but still unable to harvest the energy due to unavailability of ingenious technology. Coal gasification is robust, efficient and environmental friendly technology but it is highly sensitive to the coal characteristics. Scant literature is available on the development of the coal gasification technology which suits the characteristics of indigenous coal reserves. This papers presents the simulation of entrained flow gasifier for using indigenous coal through process modeling software namely Aspen Plus® to evaluate various system flow steps within an entrained flow gasifier. General techniques have also been discussed for creating the equilibrium-bases simulations of gasification systems. Peng-Robinson equation was used to correlate the volume of species with respect to state variables (temperature and pressure). The effects of composition of different indigenous coals like Thar, Lakhra and Sonda were investigated through simulations along with O/C (Oxygen-to-Carbon) ratio. Parametric study revealed that the O/C ratio along with other related system parameters have great influence on the performance. Sulfur could be available in different forms in coal like pyrite, sulfate or organic sulfur so appropriate form of sulfur in feedstocks should be corrected for better accuracy of model results. The highest percentages of CO i.e. 44.2, 37.8, and 46.6% were obtained from Thar coal (air dried form), Lakhra coal and Sonda coal respectively at the 0.3 O/C ratio. The decrease in LHV and HHV (Lower and Higher Heating Values) of syngas was observed on increase of O/C ratio for all coal types. The composition of as received Thar coal gave maximum LHV (1.5x104 KJ/Kg) and HHV (1.78x104 KJ/Kg) at the 0.3 O/C ratio. The future work could be extended by simulating biomass composition in the developed model of gasifier in transient simulations.

Proximate analysis of Lakhra coal power plant and its health and environmental impact

ABSTRACT Pakistan is one of the coal rich countries but only adds 10% of electricity to the national grid from coal fired power plants while major sources are, Hydel, LNG, Furnace oil, and natural gas. Prior to the discovery of Thar coal reservoirs, Lakhra was the largest coal field of Brown Lignite coal with high ash and sulfur contents, i.e. 30% and 7%, respectively. The power generation capacity of the plant is 150 MW. Study conducted revealed that all the existing values of un-washed coal found (High Ash, Low Moisture, Low Fixed Carbon, High Sulfur, and Low Calorific value) while the washed coal values found (Low Ash, Low Moisture, High Fixed Carbon, Low Sulfur, and High Heating value). The emission of hazardous gases and particles by using unwashed coal adversely affect the environment and human health whereas washed coal exhibited relatively low level emissions of these pollutants. It was observed that the washed coal of Lakhra is more feasible to save the environment as well as Cost Benefit for production of electricity.

Physicochemical characterization of Thar coal and torrefied corn cob

In this study, the corn cob was torrefied at five different temperatures (200, 225, 250, 275 and 300°C) for four different residence times (15, 30, 45 and 60 min). The physical and chemical propert...