Coal Mixture Research Articles

Understanding the release behavior of biomass model components and coal in the co-pyrolysis process

The release behavior of biomass model compounds, coal and their mixtures in the co-pyrolysis process were investigated. The microcrystalline cellulose (MC) and lignin were chosen as model compounds of biomass. Thermal-mass spectrometer (TG-MS) was used to inspect the release characteristics of small molecules in the heating process. The release curves of biomass model compounds and coal mixtures in co-pyrolysis process are similar to that in the separate pyrolysis process. More H2O are produced in the pyrolysis process of microcrystalline cellulose. In addition, more H2, CH4, CO and CO2 are produced during the pyrolysis process of lignin. Compared with microcrystalline cellulose and lignin, the contents of aromatic compounds in Shenfu coal are higher. For the CH4 and CO2 produced in co-pyrolysis process, the experimental values are slightly higher than the calculated values.

Efeitos causados por obstáculos na hidrodinâmica de correntes de turbidez: uma abordagem experimental

ABSTRACT This research aims to evaluate the effects of the presence of obstacles on turbidity currents hydrodynamics. Nine physical simulations of a poorly sorted mixture of water and coal (Cvol = 5%; D50 = 47 μm) were run in a laboratory test channel with three flow discharges (5, 10 and 15 L.min-1) in three different topographic configurations: runs without obstacles; runs with three 3 cm-high obstacles and runs with three 6 cm-high obstacles. The results showed that greater height of obstacles leads to greater blockage of the flow, causing changes on vertical profiles of velocity shape, flow regime (supercritical to subcritical), geometry and flow circulation in the zone between obstacles. Obstacle height reduction by 50% led to similar behavior of the turbidity current as the no-obstacles condition. After passing over the sequence of the obstacle, the turbidity current tended to regenerate a hydrodynamic structure comparable to the no-obstacles conditions.

Прогноз розрахунку коефіцієнту розмолоздатності вугільних шихт.

It is shown that the method for determining the grinding ability according to Hardgrove remains and it is the most common, informative and universal of all the methods for assessing the physical and mechanical properties of solid fossil fuels from the point of view of their industrial processing. Therefore, it is of practical interest to formulate the main principles for determining the grind ability of real industrial coal charges by this method. The actual approved coal charges of the main coke-chemical enterprises of Ukraine at the time of the experiment (January 2022) were taken as objects of study. The components of the charge were distributed by grades, coal of each grade was represented by one typical component of this grade, the participation of which in the charge is the largest. The studied coal grades were subjected to technical, plastometric, petrographic, elemental and granulometric (>13; 3–13; 1–3; 0.5–1; <0.5 mm) analyzes. In addition, the indicators of oxidation of this coal were determined. The coefficients of grinding ability HGI of coal mixtures, which included coal of different degrees of metamorphism of four main grades, were determined. The presence of systematic deviations of the actual values of HGI coal charges during their joint preparation from their calculated values in the direction of decreasing the HGI coefficient (to harder coal) has been established. It has also been established that as the grind ability coefficient increases, its deviation from the calculated values decreases. A mathematical dependence has been revealed that makes it possible to predict the HGI value of coal charge according to the data on the grind ability coefficients of individual components. It is shown that forecasting the values of the HGI grind ability coefficients of coal charges by the content of vitrinite in them, as well as by the formula for calculating HGI from Vdaf, is inappropriate due to the low level of correlation and determination coefficients. Keywords: coal, coal blends, Hardgrove HGI, additivity, graphical dependencies, mathematical equations. Corresponding author V.V. Koval, e-mail: kovalen79@gmail.com

Investigation of Air-MILD and Oxy-MILD Combustion Characteristics of Semicoke and Bituminous Coal Mixtures in a 0.3 WM Fuel-Rich/Lean Fired Furnace

Investigation of Air-MILD and Oxy-MILD Combustion Characteristics of Semicoke and Bituminous Coal Mixtures in a 0.3 WM Fuel-Rich/Lean Fired Furnace

Коксування трамбованих вугільних шихт. Вміст газового вугілля ≥40 %.

COKING OF RAMMED COAL CHARGES. GAS COAL CONTENT ≥ 40% N.V. Mukina (Coke-chemical production of PJSC “ArcelorMittal Kryvyi Rih", 50095, Kryvyi Rih, Krivorozhstal st., 1, Ukraine), D.V. Miroshnichenko, Doctor of Technical Sciences (National Technical University "Kharkiv Polytechnic Institute", 61002, Kharkov, Kirpichev str., 2, Ukraine) Preliminary studies have shown that an increase in the sintering ability, determined by both plastometric and petrographic methods, and the coking capacity of a charge with a gas coal content of ≤ 40% leads to an improvement in the mechanical strength of blast-furnace coke. Graphical and mathematical dependencies have been developed to predict the mechanical and post-reaction strength indicators, as well as the reactivity of blast-furnace coke obtained from a rammed charge with a gas coal content of ≤ 40%. This paper presents similar studies, however, using coal mixtures characterized by the content of coal of the gas group ≥40%. The coal concentrates of the operating coke-chemical production, which are part of the coal charge for tamping, were studied. The initial samples were studied using a set of standardized methods with the determination of data from technical, petrographic and granulometric analysis, as well as the chemical composition of the ash. In addition, in the samples taken, the value of the Hardgrave’s grind ability coefficient and the expansion pressure in the tamped form were determined. Laboratory coking of coal charges was carried out in a five-kilogram laboratory furnace. The tamped cake was made in a separate collapsible matrix. Based on the results of experimental coking, it was found that the mechanical strength of coke obtained from coal charges, characterized by an increased (more than 40%) content of gas group coal, is most affected by the degree of metamorphism (Vdaf, R0) and expansion pressure (P10). Mathematical and graphical dependences have been developed to predict the mechanical (P25, I10) and post-reaction strength (CSR), as well as the reactivity (CRI) of coke obtained from coal blends characterized by an increased content of gas group coal. Keywords: coal, rammer, coke, mechanical strength, reactivity. Corresponding author D. V. Miroshnichenko, e-mail: dvmir79@gmail.com

Resources from coal beneficiation waste: Chemistry and petrology of the Ayrshire coal tailings ponds, Chandler, Indiana

Tailings (refuse) material, a mixture of fine coal and rock from the beneficiation of high volatile C bituminous Pennsylvanian Illinois Basin coals, was recovered from the tailings pond near the site of the former preparation plant. The material has widely varying concentrations of some elements, such as Sn, which might reflect non-coal contamination of the product stream at any point from mining and beneficiation of the coal to disposal of the waste product. The rare earth elements have a strong M-type enrichment. Concentration of the rare earths is below what would normally be considered to be an economic grade. The mix of coal and REE-lean rock, though, implies that the resource must be examined with an eye towards the recovery of critical elements, not just for the reconnaissance bulk characterization, as was done here. Despite the low concentration of REE and other critical elements, factors such as the ease of moving the comminuted, near-surface material and its proximity to highway, rail, and river transport implies that such resources must be carefully examined; not simply dismissed because the grade is below a cutoff level developed for coal, not mixed rock + coal.

Innovative ways to control dust and explosion safety of mine workings

Ensuring dust and explosion safety during underground coal mining is one of the most important tasks of industrial safety and labor protection departments. The main method of preventing explosions of coal dust settled in mine workings is to process them with stone dust (rock dusting). The traditional methods of quality control of rock dusting include radioisotope, optical and chemical methods. To implement them, the devices are equipped with environmentally harmful radioactive elements, expensive optical sensors, desiccants and replaceable flasks with chemical reagents, which increases the cost of analysis and its duration. The measurement error of these devices is 10 % or more. The main purpose of the study is to develop and substantiate a new method for monitoring the dust and explosion safety of mine workings, which will be devoid of the disadvantages of the methods mentioned above. It is proposed to evaluate the quality of rock-dust distribution by a fundamentally new way – thermogravimetric. The method was tested on the dust of coal mines in Kuzbass and the Vorkuta basin, including dust samples taken in mines with actual explosions. The article presents the results of experimental studies of the processes of thermal destruction of coal and stone dust mixtures. The non-overlapping intervals of the thermogravimetric reaction are identified: moisture yield (35-132 °С); volatile matter yield from coal (380-580 °С); thermal degradation of limestone with carbon dioxide yield (650-850 °С). Methods and mathematical dependencies for processing significant and qualitative identification characteristics of thermogravimetric curves in determining the content of non-combustible components in a sample of mine dust are considered.

Reclamation of cutting oil waste to refuse derived fuel: A life cycle assessment approach for a waste-to-energy system

Reclamation and reuse of spent oil waste are preferable resource management practices that provide energy and environmental benefits. This study aims to have a comprehensive understanding of the environmental benefits and tradeoffs regarding the reclamation of cutting oil waste to refuse-derived fuel (RDF) for steam generation through a life cycle assessment (LCA) approach, with special attention given to pollution characteristics during steam generation. Our results confirmed that majority of the environmental impacts associated with the reclamation process (approximately 78.9%) could be attributed to the electricity consumption involved in the process, which could be offset by the energy savings from the avoided oil waste disposal. Thus, the involvement of RDF in steam generation may enhance the environmental performance of the waste-to-energy system from two aspects, including a reduction in global warming potential (22.2%–99.6%) from decreased fossil fuel consumption and a reduction in toxicity impacts (68.2–71.5%) from minimized pollutant emissions under improved combustion efficiency compared to other tests. The global warming potential for generating 1 ton of steam was found to be the lowest at approximately 0.15 kg CO2 eq using a mixture of RDF and wood dust and the highest at approximately 41.18 kg CO2 eq using a mixture of coal and wood dust. Additionally, pollutant emissions from steam generation were identified as a significant contributor to the overall impacts, in which terrestrial ecotoxicity was found to be the most sensitive impact to the reduction of pollutant emissions in all runs. Future practical efforts for waste oil-to-energy systems are suggested to focus on the implementation of pollution control measures that minimize their associated impacts while maximizing their benefits.

Ash Evaluation of Indonesian Coal Blending for Pulverized Coal-Fired Boilers

Coal calorific value is one of the main considerations for using coal as a power plant fuel. In addition, the requirements for indications of slagging and fouling are also important to maintain combustion efficiency. However, coal power plants often experience problems in boiler operations due to the use of certain types of coal, even though they have a relatively high calorific value. This research investigates the effect of coal blending on ash fouling and slagging in an experimental investigation using a drop tube furnace with or without additives. Five different types of coal from different locations have been used in this study. Pulverized low-rank coal samples are burned in a drop tube furnace at 1,175°C with probe temperatures of 550°C and 600°C, corresponding to the combustion chamber of 600 MW power plants, including superheater and reheater areas. The ash particles’ characteristics and material composition were also analyzed using scanning electron microscopy with energy-dispersive X-ray (SEM-EDX) and X-ray diffraction (XRD), respectively. All coal mixture combinations demonstrated potential as a fuel for power plants that use pulverized coal-fired boilers. Because of its capacity to reduce slagging and fouling potentials, combining coal blending with the use of chemical additives yielded the greatest results.

Enhanced Combustion of Bituminous Coal and Semicoke Mixture by Ferric Oxide with Thermographic and Kinetic Analyses.

We study the specific catalytic effect of the catalyst on the combustion process of pulverized coal of increasing the proportion of semicoke in the mixture of semicoke and bituminous coal, and reducing the cost of blast-furnace coal injection. A combination of thermogravimetric and kinetic analyses were used to study the catalytic effect of Fe2O3 on semicoke and bituminous coal, and to improve the amount of semicoke in the mixed coal powder of bituminous coal and semicoke. Experimental results showed that Fe2O3 had a catalytic effect on both semicoke and bituminous coal, but there were differences in the catalytic stages of the same catalyst for different pulverized coal types. The addition of 2 wt % Fe2O3 to semicoke and bituminous coal each led to the ignition temperature and maximal burning rate temperature of the semicoke decreasing, indicating that the catalyst promoted the precipitation of a volatile fraction from the semicoke. The maximal burning rate temperature and burnout temperature of the bituminous coal decreased, and maximal weight loss rate increased, indicating that the catalyst promoted the combustion of the fixed carbon of bituminous coal. The optimal proportioning amount of semicoke in the mixed coal powder without the addition of a catalyst was 25%. After adding 2 wt % Fe2O3, the proportional amount of semicoke increased by 10%. The addition of the catalyst resulted in even lower activation energy for the same conversion rate. When the conversion rate was in the ranges of 0.1–0.2 and 0.5–0.7, the activation energy decreased by 22% and 26%, respectively, compared with that without a catalyst. Fe2O3 promoted the combustion of bituminous coal and semicoke. This enhanced the combustion performance of the pulverized coal mix and increased the proportion of semicoke in the mix, which has certain guiding significance in reducing the cost of blast-furnace iron making.

A Study on the Hard Coal Grindability Dependence on Selected Parameters

A very important aspect of proper preparation of the coal mixture for the coking process is its appropriate grinding. One of the parameters describing the energy input required for grinding is the Hardgrove index. This research was undertaken to determine the dependence of the Hardgrove grindability index on selected physicochemical properties of coal. The Hardgrove grindability index was determined using the available methods described in the standards, and the dependence on selected parameters was examined. A clear positive correlation with calorific value and smaller (also positive) correlations with moisture content and free swelling index was obtained. A slight negative correlation was also obtained with sulfur content.

Computational analysis of influence of particle size, oxygen concertation, and furnace temperature on the ignition characteristics of pulverized high ash and high moisture coal particle

Energy is a critical component in any given region's growth. India has the world's fourth-largest coal reserves. Therefore, energy generation from coal-based power plants is still a significant source of power in the country. However, the performance of Indian coals is poor compared to foreign coals such as South African, Indonesian, and US coals due to the high ash and moisture content. Seventy percent of country electricity need is still dependent on coal power even with known negative environmental consequences such as the production of CO2 & greenhouse gases, and air pollution caused by SOx, NOx, coal sludge, coal dust, and by-products of coal combustion. In this work, effect of coal types, particle sizes, and furnace temperatures on the ignition delay time of pulverized coal particle is investigated. In the current study, the ignition delay time of four Indian coals (IS1, IS2, IS3, and IS4), two Indonesian coals (IAS1 and IAS2), and one South African coal (SA1) were examined for particle sizes ranging from 35 to 115 µm, furnace temperature ranging from 1000 to 1700 K, and oxygen concentrations ranging from 12 to 20% in gas. Furthermore, ignition delay analysis of different coal mixtures (Indian and foreign coals mixtures) has also been studied. Numerical analysis of ignition delay time has been performed using MATLAB. Results show that the ignition delay time of coal particles increases with a decrease in furnace temperature and an increase in particle size. Results also show that the Indian coals have a larger ignition delay time than other considered coals, and ignition characteristics of Indian coals can be enhanced by mixing with high-grade ones. An increase in oxygen concentration also reduces the ignition delay time of the coals.

Road performance analysis of cement stabilized coal gangue mixture

In order to solve the environmental pollution of coal gangue and the shortage of aggregate resources in road engineering, waste coal gangue is used as road base material instead of natural stone materials. Through physical, mechanical, chemical and activity tests of coal gangue aggregate, the optimal gradation composition of unconfined compressive strength was determined. Through unconfined compressive strength, indirect tensile strength, flexural tensile strength, freeze-thaw and dry shrinkage tests, the influence of cement content on road performance of cement stabilized coal gangue mixture was studied. By means of SEM, ICP AES, XRD and optical digital microscope, the difference between spontaneous combustion coal gangue and Unspontaneous combustion coal gangue was analyzed, the microstructure of cement stabilized coal gangue mixture was characterized, and the strength formation mechanism of mixture was explored. The results show that Spontaneous combustion coal gangue has higher activity than Unspontaneous combustion coal gangue. Based on the selected optimal allocation (BNS:SNS:SSC = 71.26:9.41:18.8). The mixture of 4% cement dosage can not only meet the requirement of early strength 4.16 MPa, but also show an efficient strength growth rate of 36.10%, showing the optimum mechanical properties. The total shrinkage coefficient of cement stabilized coal gangue mixture with 4% cement dosage is 1.12 × 10−2, which shows that the dry shrinkage resistance is the best. With the increase of time, hydration degree is gradually deepened, and gelled substance is more tightly bonded to aggregates. There is no obvious gap between aggregates, and the integrity of the mixture is enhanced, which can show better road performance. Ca (OH)2, a cement hydration product in cement stabilized coal gangue mixture, takes place pozzolana reaction with active SiO2 and Al2O3 in coal gangue to produce gismondine, which is beneficial to the global strength and the bond quality of the mixture.

FINANCIAL ANALYSIS OF GREEN PETROLEUM COKE AS A COAL BLEND IN STEEL INDUSTRY TO SUPPORT NATIONAL ENERGY SECURITY

Green Petroleum Coke (GPC), produced by Pertamina RU II Dumai, is the product of refined petroleum, which still has good quality but has not been utilized to its full potential. Such as Sulfur 0.5%; FC 86.03%; Ash 0.10%; VM 13.82%; Moist 10, 52%; and the calorific value of 7500 kcal/kg. Therefore, one effort that can do is diversification, namely the use of GPC as a mixture of other fuels (fossil) to increase the selling value of GPC. This diversification is also in line with the national energy policy in PP. 79/2014 that the program aims to increase the availability of national energy sources. This study aims to determine the feasibility of using GPC as a coal mixture in Industry (Krakatau Steel) with an overview of economic aspects. Data obtained by qualitative methods consisting of interviews, observation, and documentation. Based on the research results from 2 scenarios, both scenario 1 (GPC 4%) and scenario 2 (GPC 18%), it is found that the NPV is positive, IRR is above the discount rate, and BCR> 1. Thus, the use of GPC as a coal mixture is considered feasible to run and can support national energy security.Keywords: Diversification, Feasibility, Petroleum Coke, Investment DecisionJEL: G11, G32

Integration of protective mining and underground backfilling for coal and gas outburst control: A case study

Mining protective coal seams is an effective approach for coal and gas outburst control, but a large amount of gangue is usually produced when mining a thin protective seam and dealing with the gangue can be a challenging task. In the paper, a novel integrated mining system by extracting two panels simultaneously was demonstrated in the 12th coal mine of the Pingdingshan coalfield: one panel was mined in the thin protective coal seam, and the other one was mined in the protected coal seam. The thickness of the protective seam was only 0.8 m, but the mining height reached 1.8 m, indicating that there was about 1 m thick roof stone being mined. An underground coal preparation plant was built, and the mixture of coal and gangue from the protective panel was sorted underground. The sorted coal was delivered to the surface stockpile, while the waste rock was directly backfilled into the gob of the panel in the protected coal seam. Thus, waste rock did not need to be lifted up to the surface, which can reduce material handing cost and minimise mining footprint on the surface. In order to prevent the migration of pressure relief gas into the working areas of the protective coal seam, the main reasons causing gas exceedance in the upper corner of U-shaped ventilation system were investigated, and then the Y-shaped ventilation system and various gas extraction boreholes were implemented to effectively control the pressure relief gas. Numerical models were developed to assess the effect of applying gob backfilling during the extraction of two panels in parallel. The results show that the gob backfilling can reduce the surface subsidence and horizontal movement, which is very helpful for the protection of ground water and surface infrastructures.

Mechanical Properties of Furnace Slag and Coal Gangue Mixtures Stabilized by Cement and Fly Ash.

The mechanical properties and strength formation mechanism of cement–fly-ash-stabilized slag–coal gangue mixture were examined using an unconfined compressive strength test, splitting strength test, triaxial test, and scanning electron microscopy to solve the limitations of land occupation and environmental pollution that is caused by fly ash from the Xixia District thermal power plant in Yinchuan, slag from the Ningdong slag yard, and washed coal gangue. Its performance as a pavement base mixture on the road was investigated. The results demonstrated that as the slag replacement rate increased, the maximum water content increased while the maximum dry density decreased. The addition of slag reduced the unconfined compressive strength and splitting strength of the specimens; furthermore, the higher the slag substitution rate, the lower the unconfined compressive strength and splitting strength of the specimens. As the cement content increased, the specimen’s unconfined compressive strength increased. Based on the principle of considering the mechanical properties and economic concerns, the slag replacement rate in the actual construction should be ~50% and should not exceed 75%. Based on the relationship between the compressive strength and splitting strength of ordinary concrete, the relationship model between the unconfined compressive strength and splitting strength of cement–fly-ash-stabilized slag–coal gangue was established. The failure mode, stress–strain curve, peak stress, and failure criterion of these specimens were analyzed based on the triaxial test results, and the relationship formulas between the slag substitution rate, cement content, peak stress, and confining pressure were fitted. As per the SEM results, the mixture’s hydration products primarily included amorphous colloidal C-S-H, needle rod ettringite AFt, unhydrated cement clinker particles, and fly ash particles. The analysis of the mixture’s strength formation mechanism showed that the mixture’s strength was the comprehensive embodiment of all factors, such as the microaggregate effect, secondary hydration reaction, and material characteristics.

Influence of the synergistic effects between coal and hemicellulose/cellulose/lignin on the co-combustion of coal and lignocellulosic biomass

The co-combustion behaviours and the synergistic effects between coal and lignocellulosic biomass, and coal and hemicellulose/cellulose/lignin were investigated under a high heating rate condition. The temperatures of the tested samples were obtained with the radiant energy analysis technology. The results show that all the samples ignite homogeneously. The synergistic effects between bituminous coal and peanut shell during the devolatilization process promote the homogeneous ignition and char ignition of the bituminous coal and peanut shell mixtures. The synergistic effects between bituminous coal and cellulose during the devolatilization process promote the homogeneous ignition of the mixtures, which results in the synergistic effects between bituminous coal and peanut shell on the homogeneous ignition and char ignition of the mixtures of bituminous coal and peanut shell. The synergistic effects between bituminous coal and lignin inhibit the char ignition of the mixtures of bituminous coal and lignin, but are not obvious on the char ignition of the mixtures of bituminous coal and peanut shell.

Morphology, composition and mixing state of individual airborne particles: Effects of the 2017 Action Plan in Beijing, China

Beijing is one of the most important Chinese megacities with extremely serious air pollution problems and human health impacts. In response to the air pollution the central and municipal governments of China have implemented a series of actions; one of which is the “Action Plan for Comprehensive Prevention and Control of Autumn and Winter Air Pollution in Beijing-Tianjin-Hebei and Surrounding Areas 2017–2018” (the Action Plan) issued in 2017. The morphology, composition and mixing state of individual particles collected after the Action Plan was implemented were analyzed by high resolution-transmission electron microscopy coupled with an energy-dispersive X-ray spectrometer (TEM-EDX). The relative percentages of different individual particle types and the main sources of the particulate pollution before and after the Action Plan were compared. The results showed that sulfur was most frequently detected in the individual particles, and the particle types were mainly composed of soot aggregates, mineral particles, organic particles, metal particles, coal fly ashes, sulfate particles, and mixture particles. The mixture and sulfate particles dominated in the autumn samples, both for the haze and non-haze days. In winter the mineral and mixture particles dominated in samples for the non-haze days, while mixture particles and sulfate dominated in the samples for the haze days. The mixture particles in autumn were mainly the soot aggregates internally mixed with sulfate (S-soot type), while the mixture particles in winter were mainly the S-soot type and the mineral particles internally mixed with sulfate (S-mineral type). After the Action Plan, the relative percentages of sulfate particles, organic particles, and soot aggregates increased, while the relative percentages of mineral particles, metal particles and fly ashes decreased. The contribution from coal-fired sources was reduced significantly as evidenced by the decrease in the fly ash particles. The vehicle emissions and secondary reaction of particulate matter became the main sources of atmospheric particulate matters as evidenced by increase in sulfate particles, organic particles, and soot aggregates. The results presented in this study will assist in other plans to improve air quality and human health in megacities around the world.

Mathematical modeling of the thermochemical processes of sequestration of SOx when burning the particles of the coal and wood mixture

The article presents the results of mathematical modeling of the initial stage of the combustion of wood and coal particles in conditions corresponding to the combustion chambers of boiler units of thermal power plants. A hypothesis is formulated that describes the sequestration of anthropogenic sulfur oxides (SOx) under the conditions of combustion of mixed fuels based on coal and wood as a result of the interaction of water vapors (formed during the evaporation of interporeal and adsorbed biomass moisture) with SOx with the formation of sulfuric (H2SO4) acid vapors. When these vapors of sulfuric acid H2SO4 interact with iron oxides of the mineral part of the coal. To test the formulated hypothesis, a new mathematical model has been developed for the processes of co-ignition and combustion of wood and coal particles under high-temperature heating conditions. The mathematical model of the ignition process developed by the authors differs from the known ones (published in leading international scientific periodicals on the combustion of solid fuels) by a detailed description of a complex of gas-phase and heterogeneous thermochemical reactions occurring both in the boundary layer of fuel particles and in their porous structure. The mathematical model of the combustion process of wood-coal fuel particles developed by the authors is currently the most detailed in describing the thermophysical, thermochemical and aeromechanical processes occurring both in the fuel particles and in their small vicinity. Multistage kinetic schemes for the oxidation of the main volatile components (methane ‒ CH4, carbon monoxide ‒ CO, hydrogen ‒ H2), as well as the formation of sulfur oxides by means of oxidation of hydrogen sulphide (H2S), released as a result of pyrolysis of the organic part of coal, have been adopted. Based on the results of numerical modeling, the possibility of intensifying the processes of sequestration of sulfur oxides by moistening the wood component of the fuel mixture has been established. It is shown that water vapor can act as an agent adsorbing anthropogenic sulfur oxides, transforming the latter into sulfuric acid vapor, respectively. In turn, the vapors H2SO4 and HNO- 3 can be relatively easily captured by means of condensation. It has been established that for effective SOx capture during co-combustion of coal and biomass, the moisture content of the latter must be at least 5% by weight. The research provides grounds for the conclusion about the possibility of environmentally efficient combustion of coal in the composition of wood-coal fuel composites.

Valuation slagging factors and greenhouse gases emissions of paper mill reject and coal

There are quite a lot of paper mill rejects (PMR) as a by-product of paper mills and have not been utilized, currently. The purpose of this study is to evaluate the characteristics of paper mill reject (PMR) to coal and natural biomass and estimate the greenhouse (GHG) emissions of PMR and coal. Coal and PMR taken from five paper mills were analyzed for the content of moisture, proximate parameter (ash, volatile matter, fixed carbon), sulfur (S), gross calorific value (GCV), ash mineral and ash fusion temperature (AFT). The slagging factors of materials were calculated and evaluated. The resulting greenhouse gasses (GHG) emissions was also estimated. The results show that with the high calorific value, low ash and sulfur content of PMR, it has the potential to be used as a coal mixture for boiler fuel. It is very beneficial for the environment due to the low SO2 emissions. PMR has the characteristics of a low slagging index (SI), high fouling index (FI) and Slag Viscosity Index (SVI) which is almost similar with biomass, empty fruit bunches (EFB) and rice husk. The use of PMR as a coal mixture in paper mills in the amount of 10,285 ton/year can reduce greenhouse gases of 63.5 tons CO2-equivalent/year.