Coal Type Research Articles

Identification of slurry fuel components in a spray flow

The paper presents the experimental research findings for the spraying characteristics of promising composite fuels. Slurries were produced from typical coal processing waste (filter cake), a liquid bio-additive (rapeseed oil), biomass (sawdust) and a liquid noncombustible binder (water). The most important spraying characteristic is the distribution of fuel components in a jet. Optical recording techniques (Laser Induced Fluorescence, Interferometric Particle Imaging and Shadow Photography) were used to study it. A fluorophore (Rhodamine B) was used in the experiments. A group of light filters was also employed for wavelengths 580–680 nm. The research made it possible to identify zones, containing individual components and/or their mixtures, in a sprayed fuel jet. The average concentrations of coal processing waste in individual droplets and in an overall aerosol flow were recorded. The proportion of droplets containing wood biomass in a spray flow was determined. A method was proposed to reliably determine the structure of fuel jets with different component compositions. The method involves combining three optical techniques. The experimental data obtained make it possible to predict the conditions for efficient ignition and combustion of slurry fuel components in combustion chambers, taking into account their separation and atomization when they are sprayed by nozzles.

Coalbed methane geology and exploration potential in large, thick, low-rank seams in the Bayanhua Sag of the Erlian Basin, northern China

The Erlian Basin may be one of the most promising areas for low-rank coalbed methane (CBM) in China. The Cretaceous coal-bearing strata in the Bayanhua sag contain abundant low-rank CBM resources with suitable depths and large coal thicknesses (1.00–78.85 m, avg.22.53 m). However, the research on CBM geology and exploration potential is still lacking, which severely hinders its exploration and development. This paper presents an integrated study of CBM geology in terms of gas reservoir properties, gas-bearing characteristics and controlling factors. The results of the analysis show that lignite and subbituminous coals are the main coal types present in the study area, with medium porosity (7.3–27.8%, avg.20.77%) and low permeability (0.05–21.8 mD, avg.5.54 mD) being dominant. The pores are dominantly transition pores with inkpot shapes, which is beneficial to the adsorption of CBM. The gas content of the coal seams is 1.66–4.45 m3/t and most coal reservoirs are oversaturated. The CBM is primarily of secondary microbial origin, mostly carbon dioxide reduction. The accumulation of CBM is mainly influenced by the structure type, roof lithology and hydrogeology in the study area. According to the integrated analysis of the vertical changes in the physical properties and gas-bearing characteristics, the dominant horizon tends to be the No. 6-7 coal seam, followed by the No. 6-4 coal seam. Based upon the CBM geology and the factors controlling enrichment, the prospecting potential in the Bayanhua sag was appraised, and two favorable areas are proposed for CBM exploitation.

Fracture Characteristics and Failure Modes of Coal, Sandstone, and Shale Impacted by Water Jet under True Triaxial Conditions

In recent years, the water jet technology has become an important means for processing unconventional oil and gas resources. With the exploitation of resources to the deep development, the study of the fracture characteristics and failure modes of true triaxial water jet rock breaking is of major importance for the application of the water jet technology in deeper crustal levels. We selected three typical unconventional gas reservoirs, coal, sandstone, and shale, as samples for our rock-breaking experiments of water jet under true triaxial conditions. On the basis of the rock failure criterion considering triaxial stress, we establish the rock-breaking energy criterion of water jet under true triaxial conditions and study the rock-breaking mode of water jet under true triaxial conditions. Experimental results document that the true triaxial water jet rock-breaking energy criterion can predict the rock-breaking threshold pressure well. With the increase of triaxial stress, the breaking threshold pressure of coal, sandstone, and shale increased by 92, 38, and 37%, respectively. Under true triaxial conditions, the failure characteristics and failure modes of different rocks impacted by water jet differ significantly. The water wedge action of coal is weakened, the volume of the crushing pit was reduced by 90%, and the failure is mainly caused by the shear failure that is induced by jet pressure. Sandstone is still dominated by the denudation failure that is caused by jet, but the degree of destruction is weakened, and the volume of the crushing pit was reduced by 38%. The shale has changed from tensile failure that is dominated by stress waves to erosion pit failure that is dominated by shear action. The results of the study provide a reference for the application of the water jet technology for the exploitation of unconventional oil and gas resources in deeper crust levels.

Preparation and micro-wetting mechanism analysis of highly permeable-moistening additive for coal seam water injection based on plant extraction technology

To further reduce the concentration of dust in coal mining, improve the working environment, ensure the occupational safety and health of miners, and improve the safety construction level of intelligent mines, in this study, alginate from Enteromorpha prolifera was extracted by plant extraction technology to prepare sodium alginate. Then, the extracted sodium alginate was modified by free radical polymerization graft copolymerization theory combined with micro-wetting mechanism to develop a strong permeability and moisturizing material suitable for specific coal types, and the characteristics of the material were tested and characterized. Through molecular dynamics simulation of the highly permeable and moistening material, the wetting mechanism of the material is clarified, and the diffusion coefficient of water molecules in gas coal is 1.37×10−4 cm2/s, It provides theoretical support for the technical system of mine dust prevention and control. Finally, the synthetic material is applied to the coal seam water injection process of the Qiwu coal mine so that the average dust reduction rate of total dust and exhalation dust before and after application is increased from approximately 50% when using the conventional surfactant to approximately 80% when using the strong permeability and moistening synthetic material. The effect is obviously better than that of the conventional surfactant, and the application effect is more remarkable.

The Influence of Pore Distribution of Coal Char in the Char Fragmentation and Included Minerals Partitioning: A Percolation Modeling

The processes of char fragmentation, including mineral partitioning and particulate matter (PM) formation during dense and porous char combustion, were observed by a site percolation model. This model simulated the diffusion-controlled regime of char combustion, and the size distributions of included minerals in typical bituminous coal were determined by the computer-controlled scanning electron microscope (CCSEM), and the data were put into the char matrix randomly. The model presents the influence of initial pore distribution on char oxidation and fragmentation, the impact of the char conversion process on the extent of fragmentation, the change of ash distributions with the char conversion, and the particulate matters (PM) size distribution, which is derived from the consequence of the competition between char fragmentation and included minerals partitioning and coalescence. The results indicate that with increasing initial char porosity (φ), the number of large size pores increases but the number of pores decreases, which leads to open pores increasing, close pores decreasing, and the surface reaction area increasing. While φ ≥ 0.4, char fragmentation obviously occurs during the stage in which the rates of char conversion are 0.4–0.6, and it looks as though the maximum value of fragmentation will transfer to an earlier conversion stage if it has a larger φ. The enhanced φ shows a positive effect on the increase in the number and concentration of PM < 10 μm (nominally aerodynamic diameter), this is attributed to char fragments more drastically, and the probability of mineral coalescence reduces a lot.

Experimental and modeling investigation on char combustion and char-nitrogen evolution characteristics under different conditions

The proper description of char combustion and char-nitrogen (char-N) evolution characteristics are imperative to analyze the operating performance of decoupling combustion systems. The char-O2 combustion and char-CO2 gasification reactivity of three typical coal chars, including lignite, bituminous, and anthracite, was tested in a lab-scale fixed-bed reactor in the temperature range of 1023 K–1223 K. The relevant chemical kinetic parameters were determined by applying a one-dimensional packed-bed reactor model embedded with a lumped particle model. Meanwhile, a 1-dimensional spherical particle model is necessary for describing the char-N conversion behaviors. Experimental results show that the conversion rate of char-N in the entire bed to NO (XNO, bed) gradually decreases with increasing temperature, and the decrease of coal rank leads to a decline in the NOx emission. Further simulation results indicate that for a single char particle in the initial combustion stage, if the char particle size increases (0–1000 μm), the external gas mass transfer coefficient decreases (0–5 m·s−1), or the oxygen content decreases (0–20%), the char-N conversion to NO (XNO, p) will gradually decrease. However, due to the complicated effects of temperature on multiple factors, involving reactivity, CO/CO2 ratio in products, and dual nature of CO influence on char-NO reaction, the relationship between char-N conversion and temperature for a single particle is not fixed. When the oxygen concentration is low, the XNO, p increases as temperature rising; while, an opposite trend may be formed under high oxygen conditions.

Experimental simulate on hydrogen production of different coals in underground coal gasification

Research on hydrogen production from coal gasification is mainly focused on the formation of CO and H2 from coal and water vapor in high-temperature environments. However, in the process of underground coal gasification, the water gas shift reaction of low-temperature steam will absorb a lot of heat, which makes it difficult to maintain the combustion of coal seams in the process of underground coal gasification. In order to obtain high-quality hydrogen, a pure oxygen-steam gasification process is used to improve the gasification efficiency. And as the gasification surface continues to recede, the drying, pyrolysis, gasification and combustion reactions of underground coal seams gradually occur. Direct coal gasification can't truly reflect the process of underground coal gasification. In order to simulate the hydrogen production laws of different coal types in the underground gasification process realistically, a two-step gasification process (pyrolysis of coal followed by gasification of the char) was proposed to process coal to produce hydrogen-rich gas. First, the effects of temperature and coal rank on product distribution were studied in the pyrolysis process. Then, the coal char at the final pyrolysis temperature of 900 °C was gasified with pure oxygen-steam. The results showed that, the hydrogen production of the three coal chars increased with the increase of temperature during the pyrolysis process, the hydrogen release from Inner Mongolia lignite and Xinjiang long flame coal have the same trend, and the bimodality is obvious. The hydrogen release in the first stage mainly comes from the dehydrogenation of the fat side chain, and the hydrogen release in the second stage mainly comes from the polycondensation reaction in the later stage of pyrolysis, and the pyrolysis process of coal contributes 15.81%–43.33% of hydrogen, as the coal rank increases, the hydrogen production rate gradually decreases. In the gasification process, the release of hydrogen mainly comes from the water gas shift reaction, the hydrogen output is mainly affected by the quality and carbon content of coal char. With the increase of coal rank, the hydrogen output gradually increases, mainly due to the increasing of coal coke yield and carbon content, The gasification process of coal char contributes 56.67–84.19% of hydrogen, in contrast, coal char gasification provides more hydrogen. The total effective gas output of the three coal chars is 0.53–0.81 m3/kg, the hydrogen output is 0.3–0.43 m3/kg, and the percentage of hydrogen is 53.08–56.60%. This study shows that two-step gasification under the condition of pure oxygen-steam gasification agent is an efficient energy process for hydrogen production from underground coal gasification.

Identification and monitoring of coal dust pollution in Wucaiwan mining area, Xinjiang (China) using Landsat derived enhanced coal dust index.

Coal dust is the main pollutant in coal mining areas. Such pollutants easily diffuse and are difficult to monitor, which increases the cost of environmental pollution control. Remote sensing technology can be used to dynamically monitor mining areas at a low cost, and thus, this is a common means of mining area management. According to the spectral characteristics of various ground objects in remote sensing images, a variety of remote sensing indexes can be constructed to extract the required information. In this study, the Wucaiwan open-pit coal mine was selected as the study area, and the Enhanced Coal Dust Index (ECDI) was established to extract the coal dust pollution information for the mining area. A new mining area pollution monitoring method was developed, which can provide technical support for environmental treatment and mining planning in Zhundong. The results of this study revealed the following: (1) Compared with the normalized difference coal index, the ECDI can expand the difference between the spectral information about the coal dust and the surrounding features, so it has a significant recognition ability for coal dust information. (2) From 2010 to 2021, the coal dust pollution in the study area initially increased and then decreased. With the continued exploitation of the coal mines in the study area, the coal dust pollution area increased from 14.77 km2 in 2010 to 69.49 km2 in 2014. After 2014, the local government issued various environmental pollution control policies, which had remarkable results. The coal dust pollution area decreased to 36.85 km2 and 17.85 km2 in 2018 and 2021, respectively. (3) There was a great deal of pollution around mines and roads, around which the pollution was more serious. Various factors, such as wind, coal type, and the mining, processing, and transportation modes, affect the distribution of the coal dust pollution.

The retention and speciation transformation mechanisms of chromium during bituminous coal combustion: Effects of inorganic minerals and combustion temperature

Coal combustion mainly releases chromium (Cr) as particulates and may oxidize Cr into toxic hexavalent forms. A series of combustion experiments combined with thermodynamic equilibrium calculations were used to study the speciation transformation behavior of Cr during the burning of a typical bituminous coal. Iron-bearing minerals and the combustion temperature were found to be vital for enriching Cr in ash and preventing Cr oxidation at high-temperature combustion process. During coal combustion, an increasing release trend of Cr versus the combustion temperature was observed. However, the degree of Cr oxidation didn't increase with the increased temperature. The fraction of Cr(VI) reached a maximum at 800°C, but gradually decreased as the combustion temperature rose to 1000°C. Further speciation study revealed that Cr was mostly presented in illite and pyrite in coal, which can be transformed into aluminosilicate glass and hematite. The ion-exchangeable, carbonate, and organic-bound Cr were easily released and also partly converted into less soluble residual form. At high combustion temperature (> 800°C), Fe2O3 exhibited a significant effect on Cr transformation and diminished the Cr(VI) ratios in coal ash. This was beneficial to the ash disposal or reutilization since Cr was retained as stable Cr (III) compounds in ash.

Comparative evaluation of microwave and conventional gasification of different coal types: Experimental reaction studies

Effects of gasifier conditions (microwave or conventional) on the gasification characteristics of four different types of coal are evaluated by analysis of gaseous species generated during pyrolysis and gasification reactions. Four different coal samples are tested: a lignite (Mississippi), a low-ash subbituminous (Wyodak), a high-ash subbituminous (Usibelli), and a low volatile bituminous (Pocahontas #3). Gas composition, overall yields, carbon conversion efficiency, and cold gas efficiency are evaluated to compare gasification reactivity of the different coal types under microwave and conventional heating. During microwave pyrolysis (Ar atmosphere), greater selectivity of syngas species (H2 + CO) and greater overall non-condensable gas yields are observed, compared to conventional pyrolysis for all coals tested. The high yield of syngas during microwave pyrolysis is attributed to primary pyrolysis gases subsequently gasifying the char of the same sample to produce greater amounts of H2 and CO. During microwave gasification (CO2 atmosphere), selective heating and formation of hotspots within the coal enable the reverse Boudouard reaction to occur at a low bulk gasification temperature of 700 °C, which is less favorable under thermal gasification at this temperature. Yields of syngas are much higher under microwave gasification of all coals. Carbon conversion is found to have a linear correlation with volatile matter of the parent coal. Carbon conversion and cold gas efficiency are highest for coals gasified under microwave irradiation, and gasification reactivity of the four coals was determined to be dependent on the coal type.

Experimental study on the influence of wetting agent addition on the water adsorption and impact crushing dust generation of coal

AbstractThis study is aimed at investigating the influence of wetting agent addition on the water adsorption capacity, dust generation capacity and dust particle size distribution of coal. To achieve this aim, nonylphenol ethoxylate 10 wetting agent was used as an additive to prepare a 0.1% concentration solution, and a comparative test was conducted on different coal types from three coal mines in different provinces. The test results suggest that the natural saturated water adsorption time of coal was shortened by 33%–67% through wetting agent addition. Therefore, wetting agents are effective for enhancing water injection operations that require a limited construction period. The influence of wetting agent addition on the saturated water adsorption amount differed significantly for different coal types, and the wetting agent did not generally improve the saturated water adsorption rate. However, wetting agent addition alone did not lower the dust generation rate from coal. For a given moisture content, the wetting agent influenced the particle size distribution of dust generated during impact crushing differently between types of coal. For the three coal types investigated, wetting agent addition reduced the concentration of airborne by up to 8%.

Investigation of characteristics of gas and coke residue for the regime of quasi- and non-stationary steam gasification of coal in a fluidized bed: Part 1

The steam oxygen-free gasification allows deep processing of coal and obtaining gas with high contents of H2 and CO. The design of dual fluidized bed gasifiers (DFB) is considered promising. There are insufficient experimental data on the steam gasification process in DFB for more accurate mathematical modeling. The paper presents the experimental results in dynamics of the quasi-stationary and non-stationary gasification of two types of coals in a laboratory gasifier. It has been established that when using superheated steam for preliminary and main gasification process, it is possible to obtain a gas with a total content of H2 and CO of more than 75% vol, maximum cold gas efficiency 87%. The conditions for the expedient use of two chambers for gasification of coals of different degrees of metamorphism are identified. The gasification regimes that will increase H2 and CO formation in DFB are determined. This research substantiate the necessarily to use only steam in DFB for improving the synthesis gas quality.

Impact assessment of emissions from energy facilities on the Baikal natural area

This work aims to establish a technology for conducting a comprehensive assessment of the impact of energy facilities on the environment. The proposed strategy combines regulatory methods for calculating pollutant emissions and dispersion, as well as the laboratory findings on pollutant content in snow samples. To assist the technology, a scientific prototype of an intelligent decision-making support system known as WIAIS (Web-oriented Impact Assessment Information System) was developed. The proposed technology includes three principal stages: calculating the quantitative indicators of pollutant emissions, calculating the pollutant dispersion in the atmosphere, examining snow samples for the pollutant content and comparing them with the obtained results. For practical evaluation of the proposed technology, a computational experiment was performed, which assessed the impact of emissions from the boiler plants located in the Baikal natural area and powered by different types of coal. The testing was performed using the data on 48 boiler plants of various installed capacities having different equipment and located all over the Baikal nature area. Data on the main pollutants emitted by energy facilities (sulfates, nitrogen oxides, solids) were obtained. Quantitative indicators of pollutant emissions were established; thus, the total volume of pollutants amounts to 18.33 thousand tons/year. Furthermore, the largest sources of pollutants were identified, including boiler plants in Slyudyanka, Elantsy settlement, Severobaikalsk, and Nizhneangarsk settlement. Therefore, the proposed methodology can be used for environmental assessments of the existing power plants, as well as for designing new power facilities and developing recommendations for reducing pollutant emissions.

Emission characteristics and cytotoxic effects of PM2.5 from residential semi-coke briquette combustion

Coal combustion emits large amounts of PM2.5 (particulate matter with a diameter of ≤ 2.5 μm), and the emissions from different coal types differ. Clean fuels are essential in reducing PM2.5 emissions and their respiratory effects on human. This study compared PM2.5 emissions and their chemical components from four types of coal (i.e., bituminous raw-coal chunk, semi-coke briquette, anthracite, and bituminous briquette). The bioreactivies triggered by PM2.5 exposure to human alveolar epithelial (A549) cells were compared, and the emission factors (EFs) of bioreactivies were calculated. The PM2.5 EFs of semi-coke briquettes were reduced efficiently compared with those of raw-coal chunk, and their chemical profiles also differed. The contribution of total carbon and metals (i.e., S, Cl, Zn, and Pb) was higher for semi-coke briquette relative to raw-coal chunk, which may be due to the concentration effect of the semi-coke briquette preparation process. The production of lactate dehydrogenase (LDH) and reactive oxygen species (ROS) was higher for semi-coke briquette relative to raw-coal chunk at the PM2.5 exposure dose of 100 μg mL−1. The EFs of LDH and ROS for semi-coke briquette, anthracite, and bituminous briquette were substantially lower than those for raw-coal chunk, which verified the effects of clean coal on oxidative stress and cytotoxicity. Organic carbon and specific heavy metals (i.e., Cu, Fe, Ni, Zn, Pb, and Cr) were significantly correlated with cell membrane damage and oxidative stress. This study clarifies potential adverse effects of PM2.5 emissions from the combustion of various coal types and highlights the necessity of adopting clean coal to reduce PM2.5 emissions and cytotoxicity.

Experimental Study on Reasonable Adsorption Time in Determination Coalbed Methane Content

Accurate determination of coalbed methane (CBM) content is of great significance to coalmine methane prediction, methane extraction, and gas outburst prevention. The adsorption time affects the CBM content by affecting the Langmuir adsorption constants when using the indirect method to determine the CBM content. To determine the reasonable adsorption time, representative coal samples (anthracite, lean coal, and gas-fat coal) and different destruction types (soft coal and hard coal) were selected. The experimental methods used are mercury intrusion porosimetry test, N2 adsorption/desorption test, and methane isothermal adsorption test. The results show that the pore volume and the specific surface area obtained by the BJH method and BET model increase with increasing coal rank and destruction type. For anthracite soft and hard coal, lean soft coal, and gas-fat soft coal, the N2 adsorption/desorption hysteresis loop is not closed when the relative pressure is low, indicating the existence of ink-bottle pores in these coal samples. For all tested coal samples, the longer the adsorption time is, the larger of coal methane adsorption capacity, Langmuir constant a , and CBM content are. The Langmuir constant b decreased with increasing the adsorption time. Under the condition that the reliability of the measured value is 85%, the reasonable adsorption times of coal samples are 28 h for anthracite, 18 h for lean coal, and 9 h for gas-fat coal. This study has practical help to improve the determination of CBM content, the prediction of coal seam gas outburst, and the development of CBM.

Nitrogen isotopic composition of NOx from residential biomass burning and coal combustion in North China

Stable nitrogen isotope (δ15N) technology has often been used as a powerful tool to separate nitrogen oxides (NOx) produced by residential combustion (i.e., biomass burning and coal combustion) from other sources. However, the insufficient measurement of δ15N-NOx fingerprints of these emissions limits its application, especially in North China where residential emissions are significant. This study conducted combustion experiments to determine the δ15N-NOx of typical residential fuels in North China, including ten biomass fuels and five types of coal. The results showed that the δ15N of biomass varied between −6.9‰ and 2.3‰, which was lower than the δ15N of residential coal (−0.2‰–4.6‰). After combustion, the δ15N of biomass residues increased greatly, while that of coal residues showed no significant upward trend (p > 0.05). The δ15N-NOx produced by biomass burning ranged from −5.6‰ to 3.2‰ (−0.4‰ ± 2.4‰), showing a significant linear relation with δ15N-biomass. Comparatively, the δ15N-NOx derived from residential coal combustion was much higher (16.1‰ ± 3.3‰), ranging from 11.7‰ to 19.7‰. It was not well correlated with δ15N-coal, and only slightly lower than the estimated δ15N-NOx of industrial coal combustion (17.9‰, p > 0.05). These observations indicate that the δ15N-NOx of residential coal combustion is a result of the mixture of thermal- and fuel-released NOx. Based on the isotopic characteristics observed in this study, we analyzed the reported δ15N-NOx, and provided more statistically robust δ15N-NOx distributions for biomass burning (1.3‰ ± 4.3‰; n = 101) and coal combustion (17.9‰ ± 3.1‰; n = 26), which could provide guidance for scientific studies aiming to quantify the origin of NOx in North China and in other regions.

Optimization Design Analysis of Boiler Blowdown Utilization on A Rotary Coal Dryer with Drum Tilt Angle Variations

Lignite coal has dominated the use of steam power plants in recent years. Despite the consequences, which cause many problems, lignite is cheap and easy to obtain. One of the problems was mitigated by reducing the moisture content using a rotary coal dryer. Coal dryer is deemed uneconomical with the current energy sources from turbine extraction steam, electric heaters, and exhaust gas using large-powered fans. The waste energy from boiler blowdown, a water-vapored fluid discharged from the boiler to maintain water and steam quality, is being conducted to improve. Blowdown investigated in a rotary coal dryer type. The compressed air absorbed the heat from the blowdown through the steam coil. The hot air mixed with the coal in the rotary drum. A rotary drum was tested with the tilt angles of 0°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, and 90°. The research steps were designing, preliminary modeling, numerical analysis, prototyping, and experimental performing. The result shows that the moisture content has decreased significantly from 35.37% to 21.28%, within an angle of 10°. Based on an economic assessment, this coal dryer also proves that dried lignite coal has increased 4.9% economic value than bituminous coal.

Applicability of coal slag for application as packed bed thermal energy storage materials

Refractory materials are considered as the most suitable high-temperature sensible heat storage materials due to their excellent thermo-mechanical resistance and superior thermophysical properties. Unfortunately, refractories are usually too expensive. To reduce the cost of energy storage materials, the recycling of refractory industrial solid wastes into storage materials is becoming increasingly prevalent. The paper innovatively proposes to use the slags from a liquid slagging furnace of a coal-fired power plant in China as packed bed sensible heat energy storage materials. This paper characterizes the chemical compositions and thermophysical properties of three typical coal slags (Fukang coal slag, Fukang coal granulated slag, Hongshaquan coal granulated slag) and evaluates their potentials as storage materials. The results show that the three kinds of coal slags have good thermophysical properties. At 380 °C, the energy storage densities per unit volume of the three materials are 1037 MJ/m3, 986 MJ/m3 and 920 MJ/m3, respectively. Fukang coal slag has good thermal stability and durability and can be directly used for ultra-high temperature energy storage at 1000 °C. Due to the low crystallization degree, the two granulated slags have poor thermal durabilities and need to be processed at high temperatures before using them for energy storage applications.

MICROWAVE ACTED MICRO GRINDING OF ŞIRNAK ASPHALTITE SLIME, LIGNITE SLIME

In terms of the advanced technological developments in energy production the low quality coals need the most feasible technologies. it is possible to produce coal-derived products from low quality coals. On the contrary of environmental concerns of low quality coal burning, coal preparation, grinding and washing of various type of low quality coals need feasible evaluation. The grinding systems are needed in today's modern technology. In this fine grinding study, Hardgrove and Bond grindability tests are practiced over Şırnak shale, Şırnak asphaltites and bottom ash. Grinding tests ere carried out to certain weight samples conditioned in microwave oven at the fine size values in the product. The duration period are changed after grinding for 60 and 90 minutes. Şırnak asphaltite and Şırnak shale were dry milled in two different horizontal and vertical roller mills in different micro-grinders and the fineness values of 20 μm and 45 μm are determined and compared. The unit energy consumption for different types of clinker production in industrial mills has been calculated and presented comparatively. The differences in the grindability of raw materials and the amount of energy consumed in cement production were determined by experimental and industrial tests. The easiest to grind is Şırnak asphaltite and shale, while the most difficult to grind is marl. As a result of the HGI and Bond tests, they are the decisive tests in industrial-scale grinding of cement. Since materials that are easy to grind are evaluated, it has been observed in this study that clinkers with additives produced using claystone are more advantageous. Micronized grinding of soft limestone instead of marly limestone has proven to be easy. The particle size functions in the micro pulp are defined in the vertical ball mill. In the production of additive Portland cement, micronized grinding of oak charcoal and fly ash with microwave requires less energy and can be grinded more easily.

A Modeling and Optimizing Method for Electricity Current Intensity of Coal Mills

Coal mills consume a huge amount of station service electricity power of a coal-fired power plant. Meanwhile, the operation of coal mills also has a large influence on boiler combustion. Among all the operating factors, the electricity current intensity of coal mills reflects the electricity power consumption as well as operating status of coal mills. If the electricity current intensity of coal mills can be predicted by giving a set of operation parameters, the operating status can be adjusted accordingly. The electricity current intensity of coal mills can be reduced or minimized subject to the coal type parameters and the load of the boiler through optimizing the coal mill operations. This paper builds a model to predict the electricity current intensity of coal mills using a Support Vector Machine based on a set of practical sensing data. Via optimizing the hyperparameters of the model, a reasonable prediction ability is achieved. Under a given production running condition, the electricity current intensity of the coal mill decreases from 47.9 AM to 46.5 AM, which is a remarkable achievement for the coal mill running process. This method may provide a feasible online solution for coal mill optimization.