Ash Content Of Coal Research Articles

Improving the technology of extracting coal concentrate from fly ash from thermal power plants

Purpose. Study on the possibility of extracting coal underfire particles from the ash of the thermal power station by flotation. Intensification of the enrichment process of coal particles, development of a mathematical model for forecasting indicators of the ash function. Methodology. The method of fractional flotation was used to study the kinetics of the process of extraction of the valuable component. The technique of the planned experiment was applied, including the central composite rotatable plan of the second order for four factors affecting the ash content of the coal concentrate. Findings. According to fractional analysis, the concentration limit of coal particles was determined. During the flotation of fly ash, the best results were obtained on the EFM ejector type flotation machine, the yield of the foam product was 18.6 % with an ash content of 25.1 %, compared to the MFU mechanical type flotation machine, where the ash content of the foam product was 36.5 % with an average yield of 21.1 %. The optimal consumption of reagents at the level of no more than 3,500 g/t of the collector and foaming agent up to 250 g/t was determined experimentally, and the required flotation time was determined. Calculations were performed to determine regression coefficients and the degree of influence of factors on the flotation process. A mathematical model of the flotation process of TPP ash removal was determined, which characterizes the influence of the main factors. The graphs of the significance of the factors and the three-dimensional surface of the calculated response function were drawn up. Originality. The degree of influence of factors such as pulp pressure in the feed pipeline, collector consumption, foaming agent consumption, and flotation time on the process of beneficiation of TPP ash on the EFM ejector type flotation machine was determined. Practical value. The complex model makes it possible to predict the final indicators of the response function, namely the ash content of the secondary coal concentrate. The results will make it possible to improve the parameters of technological processes for the enrichment of TPP ashes.

Exploring the effect of various factors for ash content estimation via ensemble learning: Color-texture features, particle size, and magnification

Online estimation of ash content in coal based on machine vision has been paid more attention to by academia and industry. Existing research has mainly focused on feature extraction and model design for estimating ash content, but the exploration of the feature's contribution to the model is rarely reported. Therefore, this paper presented a method to analyze features' contribution to microscopic images. Expressly, ensemble learning could explicitly point out the assistance of different features to ash content estimation according to the results of weak regressors, which possessed good interpretability. Firstly, we explored the relationship among particle size, magnification, and precision to determine Adaboost as the optimal regressor. Secondly, we discussed the contribution of different features to the regressor quantitatively and qualitatively on the 0.5–0.25 (mm) particle size of datasets under magnification of 0.3, which we called the optimal condition. Ultimately, the experimental conclusions were validated by feature importance analysis and correlation analysis. The experimental results show that the magnification significantly influenced the precision of ash content estimation. Still, coal microscopic images' 0.5–0.25 (mm) particle size estimation accuracy was optimal under all magnifications. When magnification was 0.3 and particle size was 0.5–0.25 (mm), there was the best performance to ash content estimation (In the testing set, 98% of the samples had an error less than 0.5% between ash content estimated value and ash content value). Color features played a dominant role in ash content estimation in the optimal regressors. Only the building color feature regressor could achieve that 96.4% of samples had an estimated error of less than 0.5%. In contrast, only 68% of the samples using the texture feature regressors had an estimated error of less than 0.5%. Moreover, the building mixture of color and texture regressor possessed mutually reinforcing effects under specific conditions. The summarized features' contribution was essential for model building and design.

Substantiation of the Methodology for Determining Ash Content by X-ray Radiometric Method

The purpose of the research is an experimental substantiation of the methodology for determining ash content by the X-ray radiometric method. A brief overview of modern methods of coal ash content control is given. One of the independent directions of solid fuel quality control is the X-ray radiometric method. To increase the accuracy of determining the ash content of coal, a technique using two sources is proposed. The proposed method, using secondary radiation backscattered by coal and fluorescent radiation of elements, gives better results than the well-known method for determining ash content by backscattered radiatio

Study on the mechanism of adsorption and hydrophobic modification of glycerol monooleate/kerosene mixed collector on low-rank coal surface

A new collector (GK) consisting of GMO (glycerol monooleate)/kerosene was developed to address the problem that low-rank coal is difficult to be recovered by flotation with conventional non-polar oil collector. The flotation test proved that GK collector has excellent flotation performance for low-rank coal (combustible recovery rate close to 90 % while the ash content of clean coal is about 6 %). The contact angle, infiltration time, wetting heat and XPS analysis demonstrated that GK collector can significantly improve the hydrophobicity of low-rank coal, resulting in a great improvement of flotation efficiency. Molecular dynamics simulation shows that the hydrophilic head of GMO molecules can adsorb with low-rank coal directly through hydrogen bonding or indirectly through water bridges. The presence of GMO molecules in GK collector can increase the overall interaction strength of collector oil droplet with low-rank coal surface by more than half. A schematic diagram of collector adsorption on the surface of low-rank coal is drawn, which gives a complete overview of the stacking and hydrogen bonding connection modes at the molecular level of low-rank coal, water, GMO and kerosene adsorbed at the interface. The adsorption mechanism of this mixed collector on the surface of low-rank coal was clarified.

LKDPNet: Large-Kernel Depthwise-Pointwise convolution neural network in estimating coal ash content via data augmentation

Product quality monitoring is one of the most critical demands in the coal industry. Conventional coal quality analysis is offline, laborious, and lagging behind coal production. Using machine vision for determining ash content in coal has been recently developed. However, there are some challenges in the model design due to its task complexity. A data augmentation method for a specific task was proposed to deal with the peculiarities of a small, unbalanced industrial dataset. For estimating ash content in coal from an image without background, we provided a trajectory going from a ResNet to an LKDPNet under the guidance of receptive field size. First, the model depth was determined by changing the stage ratio. Second, patch embedding was employed to substitute the stem cell of ResNet for downsampling. Third, a residual connection block of depthwise convolution followed by pointwise convolution was designed to replace the ResNet identify and conv blocks. The receptive field of the model was adjusted by increasing the kernel size of the depthwise convolution layer and removing the downsampling block. The results and visualization revealed that the proposed LKDPNet could significantly improve performance with an accuracy of 98.91% and an MAE of 0.082. It could pave the way to an online analysis of coal, thus accelerating intelligent coal production.

Effect of preheating Co-firing of biomass and coal on the synergistic reduction of PM and NO source emissions

Co-firing of biomass and coal is a prevalent method in modern thermal power plants to reduce pollutant emissions. This study focuses on the preheating co-firing behavior of coal and biomass to explore the effect of preheating combustion and preheating co-firing on PM (particle matter) and NO source emissions, and different coals were selected to verify the effect of coal rank on this behavior. Coal and biomass were fed into a mixing device through two independent feeders and uniformly mixed before entering the furnace. PM and NO emissions after preheating combustion were measured using an Electrical Low-Pressure Impactor and flue gas analyzer. The results showed that preheating combustion reduced the production of PM1, PM1-10, and NO from coal by 22.30%, 10.75%, and 49.84% respectively, and also reduced the production from biomass by 28.61%, 15.16%, and 53.01% respectively compared to conventional combustion. Preheating co-firing experiments revealed that as the co-firing ratio increases, NO production decreased, but the production of PM1 initially decreased and then increased, reaching a minimum point at a co-firing ratio of 25%. Meanwhile, the lower the rank of the coal, the better the effect of preheating combustion and preheating co-firing, and the ash content and composition of coal also had an impact on the generation of PM1.

Removal of AAEMs from high alkali coal under supercritical CO2 fluid-citric acid extraction system

ABSTRACT In this paper, a method for dealkalization and upgrading of high alkali coal by supercritical CO2 fluid-citric acid extraction system is proposed. The leaching mechanism was explored by microstructural changes of elements and functional groups in coal samples, and single-factor optimization experiment was conducted. The result shows that supercritical CO2 fluid-citric acid extraction can effectively remove alkali and alkaline earth metals. The extraction mechanism is the reaction of H+ with inorganic minerals and the ion exchange of H+ with the form of phenolic hydroxyl and carboxyl groups. Under the optimum conditions, the removal rates of Ca and Mg are 44.95% and 65.75% respectively. The ash content of coal is 2.42%, and the content of Na2O (calculated by ash) is 1.13%, which meet the standards of power coal in China. Supercritical CO2 fluid-citric acid extraction is an effective and promising method for the cleaning of high alkali coal.

Design and Development of a Novel Hybrid Gasifier for High Ash Content Coal as feed stock

India has large proven reserve of coal but most of the coal has large quantity of ash. Utilization of this high ash content coal is again a verychallenging task. Presently, gasification of high ash coals has not yet been in application due to the difficulties arising from the ash handlingprocesses. In this work an attempt was made to design a partially fluidized bed reactor that can handle 30 kg/hr coal as a feedstock. By usingan appropriate design procedure a complete design of a hybrid gasifier was studied deeply. The major aim of present research is todetermine the air flow rate for proper gasification, reactor diameter and reactor height, feed particle diameter, nozzle orientation and numbernozzles, reduction zone diameter and height. Experiments were carried out with feeding rate of 9.8 kg/hr with high ash content coal having39.83% ash. Satisfactory results have been found during experiments. The average producer gas generation during trial run was found to be29.8 Nm3/hr while average calorific value of producer gas was about 4500 kJ/Nm3. The work described here favours us understand the realgasification process for high ash content coal and thus facilitates the industrial application of gasification technology.

Cone structure design for improving the separation performance of a water-only cyclone

The cone structure of a water-only cyclone is the key factor affecting its separation performance. To improve separation performance, a tri-stage curved-cone (Type Ⅲ/C) water-only cyclone was proposed and designed based on conventional cones. The flow-field characteristics and separation performance of water-only cyclones were analyzed using numerical simulation. Results indicate that the proposed Type Ⅲ/C water-only cyclone has the following superior characteristics: the pressure drop can be reduced by up to 21.43% and tangential velocity by up to 10 m/s; there are three circulating vortex cores and a thicker suspended density layer in its cone section; a continuous 0.18 mm coal particle ascent path forms; and the maximum separation distance from ash particles is 10 mm. The Type Ⅲ/C water-only cyclone had an ash content in the clean coal of 2.34% and an ash content in its underflow of 75.28%; the recovery of clean coal was 35.13%, and the recovery of clean coal combustible was 77.81%. These indicators are better than those of other conventional cyclones.

Accuracy enhancement of laser-induced breakdown spectroscopy by polarization spectrum fusion

Laser-induced breakdown spectroscopy (LIBS) has been proven to be an effective way for online analysis of coal properties (such as ash content, volatile content, and calorific value), but the quantitative analysis accuracy still needs to be improved. Herein, a polarization spectral data fusion scheme was proposed to obtain more abundant spectral information and improve the performance of quantitative analysis models. First, the polarization effect of laser-induced coal plasma emission was analyzed using the Stokes parameters of the average spectra. Due to the partially polarized phenomenon of emission, fused data of PRLIBS (0°, 0) (horizontal plasma polarization spectra) and PRLIBS (90°, 0) (vertical plasma polarization spectra) was utilized to establish an efficient prediction model to obtain high prediction accuracy. For fusion models, the root mean square error prediction (RMSEP) of ash content, volatile content and calorific values were 1.497%, 0.595%, and 0.597%, respectively, and the coefficients of determination (R2) were 0.980, 0.968, and 0.978, respectively. Comparison with regression models for individual PRLIBS (0°, 0), PRLIBS (90°, 0), and LIBS data, the data fusion scheme significantly improved the performance of the prediction model. The improvement in model performance is due to the fact that there is no perfect correlation between PRLIBS (0°, 0) and PRLIBS (90°, 0), whilst polarization spectral fusion makes it possible to acquire more number of characteristic spectral lines with high importance score. The results demonstrated the feasibility of PRLIBS spectral fusion to provide better analytical results for ash content, volatile content, and calorific values of coal.

Exploring the effect of sodium hexametaphosphate in coal slime flotation

In this paper, the influence of sodium hexametaphosphate (SHMP) in coal slime flotation was studied, and the interaction between SHMP and coal slime flotation particles was revealed through XRD test, contact angle measurement, zeta potential test, scanning electron microscopy analysis, XPS analysis, and DLVO theoretical calculation. The experimental results show that when the dosage of SHMP is 1500 g/t, the recovery rate of clean coal combustibles increases by 9.61 %. SHMP reduces the hydrophobicity of clay minerals (kaolinite) in coal slime flotation and also enhances the dispersibility of coal slime particle. Scanning electron microscopy and energy dispersive analysis showed that SHMP reduced the number of clay particles (kaolinite) on the coal surface, thereby reducing the ash content of the clean coal. In this paper, SHMP is mainly used to modify the surface of kaolinite so as to reduce the hydrophobicity of the mineral, that is, to improve the recovery rate of clean coal combustibles in coal slime flotation.

Zeolite Composite Materials from Fly Ash: An Assessment of Physicochemical and Adsorption Properties

Waste fly ash, with both low (with the addition of vermiculite) and high contents of unburned coal, were subjected to hydrothermal syntheses aiming to obtain zeolite composite materials-zeolite + vermiculite (NaX-Ver) and zeolite + unburned carbon (NaX-C). The composites were compared with parent zeolite obtained from waste fly ash with a low content of unburned carbon (NaX-FA). In this study, the physicochemical characteristics of the obtained materials were evaluated. The potential application of the investigated zeolites for the adsorption of ammonium ions from aqueous solutions was determined. Composite NaX-Ver and parent zeolite NaX-FA were characterized by comparable adsorption capacities toward ammonium ions of 38.46 and 40.00 mg (NH4+) g-1, respectively. The nearly 2-fold lower adsorption capacity of composite NaX-C (21.05 mg (NH4+) g-1) was probably a result of the lower availability of ion exchange sites within the material. Adsorbents were also regenerated using 1 M NaCl solution at a pH of 10 and subjected to 3 cycles of adsorption-desorption experiments, which proved only a small reduction in adsorption properties. This study follows the current trend of waste utilization (fly ash) and the removal of pollutants from aqueous solutions with respect to their reuse, which remains in line with the goals of the circular economy.

Experimental study on treatment of high ash coal slime by three-products flotation

ABSTRACT In this work, a three-product slime flotation experiment was conducted utilizing a two-stage direct flotation method with the BS collector and dodecane reagent system to maximize the flotation efficiency and reduce the flotation tailings along with an increase in its ash content. Modern analytical methods, such as X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) were used for analyzing the surface characteristics of the samples and their interaction with collectors. The results demonstrated a significantly higher ash content of secondary flotation tail coal compared to the primary one with increasing reagent dose. Ash content for clean coal ranges from 8.00% to 9.00% when the overall net coal output surpasses 85%, and it rises to 30.00% to 50.00% for flotation tail coal. The surface hydration membrane and BS collector form a hydrogen bond through the -OH functional group, which results in increased hydrophobicity and effectiveness of flotation.

Analysis of Water and Ash Content in Biomass Briquettes from Durian Fruit Peel Waste and Sawdust

Briquettes are used to convert biomass energy sources into other forms of biomass by compressing them so that their shape becomes even. One of the materials for briquettes uses durian peel waste and sawdust as raw materials using molasses (molasses) as adhesive. The results of this study are to bring briquettes as an alternative fuel with biomass raw materials from durian peel and sawdust using molasses adhesive, which has good quality, so that the community can utilize that. This study aimed to determine the moisture and ash content of biomass briquettes as preliminary studies. The analysis was done with carbonation and drying processes, and the resulting weight was recorded after the procedure can be known. Based on these results, the sample with 20 mesh sieves has the lowest water and ash content percentage, about 1.74% and 0.77%. Then, the sample with 30 mesh sieves has the lowest water and ash content percentage, about 1.87% and 0.78%. This value still meets the SNI 01-6235-2000 standard, where both are a maximum of 8%. Combustion the higher the coal ash content, the lower the calorific value obtained.

Insights into the interaction of polycarboxylate with coal and kaolinite and their application in flotation

Kaolinite-rich coal slurries suffer from a low yield and high ash content owing to the easy mudification of kaolinite in water during flotation. This study investigates the efficient recycling of a kaolinite-rich coal slurry using sodium polycarboxylate flotation pretreatment. The differences in the mechanism of action of sodium polycarboxylate on coal and kaolinite were investigated using high-sensitivity microelectromechanical balancer (DCAT), Fourier infrared spectroscopy (FTIR), and scanning electron microscope (SEM). The results show that sodium polycarboxylate reduces the adhesion of the coal slurry and increases the adhesion of kaolinite. Sodium polycarboxylate can cover the hydrophilic groups of –OH by binding to the hydroxyl groups on the coal surface at multiple points via the polyhydroxy structure on the molecular chain. Covering the hydrophobic potential of kaolinite increases the percentages of hydrophilic groups such as Si-O and OH in FTIR. The above findings help to elucidate the separation mechanism of sodium polycarboxylate on carbon ash and improve the flotation separation effect. The optimum dosage of sodium polycarboxylate is 4 kg/t, kerosene, and 2-octanol are 10 kg/t and 12 kg/t, respectively. The yield of clean coal is 70.43 %, ash content of clean coal is 12.62 %, which increases the yield of clean coal by 40.89 % and decreases the ash content of clean coal by 8.56 % compared to the optimum dosage of froth flotation.

Coal desulfurization by flotation method

In general, the combustion of coal containing high sulfur and ash causes negative environmental problems such as acid rain and the emission of oxides of sulfur. Coal flotation is one of the most effective methods for desulfurizing and deashing raw coal with high ash and sulfur contents before burning coal. In this study, a coal sample collected from East Kalimantan Province, Indonesia was subjected to flotation by using diesel oil as collector and pine oil as frother. The experimental results showed that 24% of the total sulfur was eliminated from coal. Also, the calorific value of coal increased from 5,486 cal/g to 5,535.38 cal/g. However, the volatile matter and ash content of coal was eliminated.

Experimental and CFD simulation of performance analysis of steam generators of boilers

Abstract In contemporary power plants, poor air temperature is one of the primary causes of rising unit temperatures and deteriorating boiler performance. The primary issue with an air preheater is air leakage on the gas flue side, which results in poor thermal performance. The high ash content of Indian coal exacerbates the issues with air tube heating. Air preheaters re developed to fulfill operational needs while taking into account the most important factors. Heat transmission, leakage, and pressure reduction are all factors to consider. The performance of the air-conditioning heater is being evaluated in this study using the Fluent 14.0 analytical tool from Computational Fluid Dynamics (CFD).

A Study on Chemical Deashing of Coal from Bulupodo Area Sinjai Regency of South Sulawesi Province Using Hydrogen Peroxide

Bulupodo coal has a fairly high ash content and low total sulphur. The main objective of this research is to reduce the ash content in Bulupodo coal. The methods used was chemical washing of coal using hydrogen peroxide (H2O2) with washing variables such as time (30 minutes, 60 minutes, 120 minutes, and 180 minutes), H2O2 concentration (5%, 10%, 15%, and 20%), temperature (45°C, 60°C, and 80°C) and particle sizes (16 mesh, 40 mesh, and 70 mesh). The results of the quality analysis show that Bulupodo coal has a moisture of 6.37%; ash 53.3%; volatile matter 26.79%; fixed carbon 14.45%; and a total sulfur of 0.53%. Hence, mineral matter analysis using microscopic and XRD (X-Ray Diffraction) show that Bulupodo coal contains kaolinite, illite, quartz, and pyrite minerals. As a result washing with the highest reduction time variable of ash content at 180 minutes was 21.63%; the concentration variable of the highest ash content reduction solution was at a concentration of 20% of 14.78%; the temperature variable for the reduction of the highest ash content at 60°C was 13.45%; and the particle size variable for the reduction of the highest ash content was at a particle size of 40 mesh of 7.32%.

Determination of ash content, volatile matter, and calorific value in coal by OLS combined with laser-induced breakdown spectroscopy based on PC recombination

The accuracy of LIBS coal quality detection was improved after PC recombination, and the main element was determined by interpretability tests.

Compaction and strength behavior of Kaolin clay stabilized with Pond ash

In India 75% electricity is produced by thermal power plants using coal. Because the majority of the nation's coal reserves are of a lower non-cooking quality, more ash will be created as a result. One of the main causes of increased ash generation is the average 35% ash content of Indian coal. Fly ash makes up a relatively minor portion of the total amount of ash produced, with pond ash and bottom ash making up the rest. Therefore, there is a need to manage this material to avoid any environmental concerns. Another issue is the presence of problematic soil, in particular, expansive clays. Their presence at any site is a challenging task for geotechnical engineer. It is because they show high signs of volume change. To tackle this issue, engineers can go with either of the two available solutions: a) replacement and b) soil modification. Keeping this in view, the present investigation focuses on the utilization of Pond ash (PA) as an admixture in Kaolin clay (KC) as a soil modification method. Hence, in this paper, strength and compaction behaviour of KC stabilized with Pond ash PA was studied. For strength characteristics, unconfined compressive strength (UCS) and split tensile strength (STS) tests were carried out. Similarly, for compaction characteristics, modified proctor compaction tests were carried out. From the test results, it was observed that the inclusion of PA in KC significantly affected its compaction and strength characteristics. The optimum Pond ash content was observed to be 30% where, OMC, MDD, UCS and STS values were 17.30%, 1.60 g/cc, 360 kN/m2 and 88.70kN/m2, respectively.