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Due to their detrimental and persistent impacts on the environment, it is imperative to manage and dispose of hazardous wastes (HW) in a secure manner. This study investigates the combustion characteristics and environmental impacts of using HW as alternative fuels in clinker production. The HW categories analyzed include industrial hazardous waste (IHW), medical hazardous waste (MHW), and household hazardous waste (HHW). Specifically, IHW consists mainly of waste mineral oils, waste organic solvents, organic resin wastes, waste residues, and waste coatings. MHW primarily consists of medical plastic products. HHW mainly includes packaging from waste pharmaceuticals, waste pesticides, disinfectants, and waste paints. Compared to traditional pulverized coal, hazardous waste alternative fuel (HWAF) exhibits a lower fixed carbon content, with its heat generation primarily dependent on volatile substances, and a higher ash content, chemically similar to coal ash. The combustion process of HWAF involves three stages: moisture evaporation (0 °C–150 °C), volatile matter combustion (150°C–400 °C), and fixed carbon combustion (400 °C–550 °C). The primary emissions from this process include CO 2 , CO, trace amounts of SO 2 , NO 2 , H 2 O, and various complex organic compounds such as carboxylic acids, alcohols, ketones, and aldehydes. While HWAF ignites more readily than pulverized coal, it burns more slowly and less completely. The incorporation of combustion by-products into the cement clinker formulation does not interfere with the clinker's hydration processes or reactions. HWAF ensures a reduced heavy metal input rate in the firing system without significantly impacting the heavy metal content in the clinker. Mortar samples produced with this clinker meet the heavy metal leaching standards, affirming the environmental safety of the cement product. Increasing the proportion of HWAF results in a reduction in standard coal consumption and an increase in CO 2 reduction, achieving a maximum coal saving of 3.67 kgce/t.cl and a CO 2 emission reduction of 10.11 kg/t.cl. This study presents a clean production model for the co-processing of HWAF, effectively transforming waste into valuable resources by using hazardous waste materials as alternative fuels. [ABSTRACT FROM AUTHOR]

The HIsmelt process uses pulverized coal and iron ore as raw materials, eliminating the need for coking and iron ore lumping compared to traditional blast furnace ironmaking processes, and significantly reducing CO2 and other pollutants emissions. However, as a new ironmaking process, the flow field, heat transfer, and combustion influencing factors of the main reactor are not resolved. Therefore, in this study, based on the consideration of fluid mechanics, heat conduction, and combustion reaction, a two-dimensional mathematical model was developed for the upper space of SRV (smelting reduction vessel), the main reactor of the HIsmelt ironmaking process, based on actual production data. The effects of hot air oxygen content and daily iron production on the velocity field, temperature field, and CO2 content field inside the SRV were investigated. The results show that as the oxygen content of hot air increases, the central airflow in the furnace develops downward, the gas temperature rises gradually, and the CO2 mass fraction generally shows a rising trend. When the daily output of iron increases, the velocity of airflow in the furnace decreases significantly, the gyratory zone moves upward; the high-temperature distribution zone in the furnace contracts; and the CO2 mass fraction decreases. [ABSTRACT FROM AUTHOR]

Coal injection is an important way to reduce the coke ratio in the blast furnace. The combustion of pulverized coal in tuyere and raceway directly affects the production efficiency of smelting. Based on the design and production data of a 2000 m3 blast furnace, a three‐dimensional mathematical model of pulverized coal combustion in tuyere and raceway is established. The lower part of the blast furnace consisting of blowpipe‐coal lance‐tuyere‐raceway and coke bed is numerically simulated to study the influence of blast rate and oxygen on pulverized coal combustion under a certain coal injection ratio and a certain coal particle size distribution. The simulation results show that the pulverized coal burnout decreases from 69.2% to 67.4% when the blast velocity is increased by 20 m s−1, and the oxygen content increases from 23% to 27%, which can improve the pulverized coal burnout and increase the temperature in the raceway. A new direction is proposed to increase the pulverized coal burnout by optimizing the particle size selection and increasing the injection ratio of small particle size below 50 μm. The research provides theoretical and data support for increasing pulverized coal burnout. [ABSTRACT FROM AUTHOR]

This paper aims to explore the effects of ultra‐low excess air coefficients on the combustion performance and NOx emission characteristics of coal‐fired boilers through industrial experiments conducted on a 600 MWe wall‐fired boiler. The results indicate that the burners demonstrate good ignition performance under different ultra‐low excess air coefficient conditions. As the excess air coefficient increases, the temperature in the main combustion zone rises, and the ignition distance of pulverized coal shortens. Under ultra‐low excess air coefficient conditions (such as 1.04), the unburned carbon content in fly ash reaches 5.50%, which is 3.23% higher than under the condition of 1.11, indicating poor pulverized coal burnout. When the excess air coefficient is close to the theoretical design value (such as 1.11), the carbon content in slag and the unburned carbon content in fly ash is relatively low (1.40% and 2.28%, respectively), indicating more complete combustion of pulverized coal. Additionally, the flue gas temperature at the air preheater outlet under this condition is relatively low; compared to the condition of an excess air coefficient of 1.07, the flue gas temperature is reduced by 6°C, thus reducing flue gas loss. Although the NOx concentration under the condition of an excess air coefficient of 1.11 is slightly higher, the quantity of cooling water is less. Flow field tracking of the powder verifies the flow path and characteristics of the primary air of the burners, and the results show that the primary air flow path of the burners is relatively concentrated, avoiding impingement on the water‐cooled walls and effectively preventing slagging issues on the water‐cooled walls. The research findings are of great significance for improving the operational performance and environmental protection level of coal‐fired boilers. [ABSTRACT FROM AUTHOR]

Oxy-steam combustion is a new oxy-fuel combustion technology. This paper focuses on the NO emission characteristics during the combustion of SF (Shen Fu) coal in O2/N2 and O2/H2O mixtures. Experiments were performed in a drop-tube furnace. Combustion tests were carried out in O2/N2 and O2/H2O atmospheres for various O2 concentrations (21%, 30%, 40%, and 60%) at different temperatures (1173 K, 1273 K, and 1373 K). In addition, combustion experiments at different excess oxygen ratios (λ) were conducted in O2/N2 and O2/H2O atmospheres. The influences of the atmosphere, oxygen concentration, temperature, and excess oxygen ratio on NO emissions were analyzed. The results show that the NO concentrations of SF coal combustion in the 21% O2/79% H2O atmosphere were much lower than those in the 21% O2/79% N2 atmosphere at the three temperatures considered. This was because a large amount of NO was decomposed during the SF coal combustion in the O2/H2O atmospheres. The reasons for the decomposition of NO include the selective non-catalytic reaction (SNCR) mechanism and char's important role as a catalyst for the destruction of NO, either directly or by reacting with CO or H2. In oxy-steam combustion, the NO concentrations significantly increased with the increase in the oxygen concentration from 21 vol.% to 60 vol.% and the temperature from 1173 K to 1373 K. The excess oxygen ratio (λ) slightly impacted the NO emissions in the O2/H2O atmosphere. [ABSTRACT FROM AUTHOR]

In this work, we attempt to explain the phenomenon of sulfur corrosion of power boiler water walls under the conditions of large fluctuations in carbon monoxide concentrations. To assess the conditions required for corrosion formation, a criterion based on the chemical and flow field parameters of the flue gas is proposed. The formulated sulfur corrosion criterion is based on the mixture fraction variance and the turbulence time scale. Numerical modeling of coal combustion in a 250 MW power boiler is performed using ANSYS. Two cases of combustion in a boiler are analyzed, with the first simulating the boiler operated using classic high-swirl burners and the second one accounting for boiler operation with modified low-swirl burners. Calculations of pulverized coal combustion are performed using the standard k- ε turbulence model and the combustion described by the mixture fraction. The simulation results reveal that the low-swirl burner is characterized by higher values of the mixture fraction variance and a higher frequency of fluctuation of the velocity field, which is strongly related to an increased corrosion rate. The study outcomes show the validity of using the criterion of the mixture fraction variance and velocity field fluctuations to determine the areas at risk of sulfur corrosion. [ABSTRACT FROM AUTHOR]

In an integrated steel plant, the pulverized coal injection (PCI) mill plays an important role in providing pulverized coal to the blast furnace. The main purpose of using PCI coal is to reduce the hot metal production cost through the utilization of non-coking coal and to extend the available coke oven life. Any unplanned outage of the PCI mill leads to increase in production cost. The three stationary grinding rollers are arranged equidistantly on the grinding plate. Each grinding roller is fixed to the pressure frame by means of a pressure yoke. Each grinding roller is borne by two roller bearings on the axle of the pressure yoke. The bearings are oil lubricated, and oil level cannot be checked in running condition due to design constraints. The bearing of new grinding roller assembly damaged within 1 service month. Bearing mode of failure was seizure, and it happened due to lack of oil. Therefore, root cause failure analysis has been carried out, and incorrect assembly was the responsible of this failure. Detailed investigation report is covered in this paper. The same type of failure can be avoided by implementing the recommendations which has been addressed in this paper. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Minerals & Processing / Huagong Kuangwu yu Jiagong is the property of Industrial Minerals & Processing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents the results of the development of stabilization measures aimed at the removal of zinc with the products of melting and accumulation of titanium in the hearth of a blast furnace. The relevance of the development and use in practice of such measures is due to the unstable fuel and raw materials conditions for the production of cast iron, when their stabilization is a complex and difficult task, as well as the need to extend the campaign of blast furnaces during the overhaul period. The negative effect of zinc oxides on the condition of the blast furnace shaft lining, accompanied by slab formation, and the overconsumption of specific coke consumption, which occurs when zinc circulates in the volume of the blast furnace, require measures to remove zinc from the smelting products. The article proposes such measures, which consist of flushing according to the proposed schedule during the operation of the blast furnace at planned blowing parameters and with the provision of the necessary thermal reserve. In order to lengthen the campaign of a blast furnace, one of the most common methods for protecting the hearth lining is the periodic introduction of titanium‐containing materials into the charge of blast furnaces. The entry of titanium oxides into the furnace, as a rule, is ensured by the use of concentrate or specially prepared ilmenite briquettes with a high titanium content as part of the sinter charge, which can be introduced directly into the composition of the blast furnace charge. The article analyzes the experience of using titanium‐containing materials as part of a blast furnace charge and formulates measures to intensify skull formation in the hearth. [ABSTRACT FROM AUTHOR]

Exploring the optimal experimental conditions and mechanism of a novel functionalized ionic liquid 1-ethyl-3-methylimidazolium bromide ([EMIM][Br]) for enhancing the wettability of coal powder is of great significance for reducing the harm of coal dust. This study determined the critical micelle concentration of [EMIM][Br] aqueous solution through ultraviolet(UV) absorption spectroscopy, and analyzed the mechanism of the influence of [EMIM][Br] aqueous solution on the wettability of coal using characterization methods such as contact angle, scanning electron microscope(SEM), automated surface area and porosity analyzer(BET), and fourier transform infrared spectroscopy(FTIR). The results showed that the critical micelle concentration of [EMIM][Br] aqueous solution was 0.005 mol/L, and the optimal experimental conditions were reaction temperature of 40°C, soaking time of 8 hours, and ratio of 1 g to 20 ml. After the action of [EMIM][Br] aqueous solution, the coal dust stomatal layer zone was developed, wedge-shaped stomata and sheet-filled cracks appeared, and the number of mesopores was increased. The content of hydrophilic functional groups such as C–O, carboxyl(–COOH), hydroxyl ether hydrogen bonds(OH...O), and hydroxyl self-consolidating hydrogen bonds(OH...OH) in the pulverized coal was increased, and the content of hydrophobic functional groups such as aryl hydrocarbons –CH3 and–CH2 was decreased, which improved the wettability of the pulverized coal. [ABSTRACT FROM AUTHOR]

Coal-fired power plants are still the way of power generation in most countries, but the CO 2 generated by coal remains high. Pulverized coal co-firing with ammonia is expected to reduce greenhouse gas emissions, which has become a hot topic. This review summarizes the progress on pulverized coal co-firing with ammonia. The effects of ammonia co-firing on the formation and transformation mechanisms of NO x and emission characteristics, as well as the emissions of other pollutants, are analyzed and summarized. This review also focuses on applying the computational fluid dynamics (CFD) sub-models in pulverized coal co-firing with ammonia. CFD is vital in pulverized coal ammonia research because of its speed and low-cost advantages. The sub-models and mechanisms of turbulent flow, heat transfer, combustion, and pollutant generation are summarized to understand better the combustion process of CFD co-combustion of pulverized coal and ammonia. Finally, the influence of pulverized coal mixed with ammonia, the CFD sub-model application, and the areas to be improved are summarized and prospected. Pulverized coal co-firing with ammonia is a feasible method to reduce carbon. This review offers fundamental theoretical support and technical guidance for the subsequent pulverized coal co-firing with ammonia. • Coal-NH 3 co-firing effectively reduces the CO 2 produced by coal combustion. • Computational fluid dynamics plays a vital role in studies on coal-NH 3 co-firing. • Classic models of computational fluid dynamics in coal-NH 3 co-firing are reviewed. • Coal-NH 3 co-firing exhibits good application prospects and some challenges. [ABSTRACT FROM AUTHOR]

With the increasing frequency and intensity of coal and gas outburst disasters under deep mining conditions, studying the outburst mechanism of occurrence has great significance for outbursts prevention and control. The evolution law of coal and gas outbursts under different gas pressure is proposed. The outbursts law is analyzed utilizing the self-developed simulation experiment system of coal and gas outbursts, and the simulation experiment is carried out under the gas pressure of 0.45, 0.8, and 1.5 MPa. In the experiment, the gas pressure drops curves, the relative intensity change, the interval distribution of coal powder, and the evolution of outburst hole and the migration rate of coal powder are analyzed. The results indicate that (1) the gas pressure detected by the No. 4 gas pressure sensor starts to drop first; (2) the gas pressure is positively proportional to the relative outburst intensity. When the gas pressure increases from 0.45 to 0.80 MPa and then to 1.5 MPa, the farthest outburst distance of coal powder increases from 10 to 15 m and then to 21 m, and the corresponding relative outburst intensity increases from 22.94% to 35.74% and then to 45.73%, respectively. (3) The average proportion of coal particles size less than 0.28 mm and larger than 1 mm under each corresponding outburst interval is 40.75% and 22.53%, respectively. Experimental results show that the gas pressure plays an essential role in the secondary crushing and pulverization of coal samples during the outburst process. (4) The throwing velocity of the pulverized coal is increased with the gas pressure near the outburst hole. When the gas pressure is 0.8 MPa, the throwing velocity of pulverized coal reaches the maximum value of 32.40 m/s. (5) The dimensional characteristics and the location initiation of the outburst hole are obtained. The results showed that the outburst process of coal is mainly in two failure forms: pulverization and spallation. The research results provide a theoretical basis and test data support for the prevention and control of coal and gas outburst disasters. [ABSTRACT FROM AUTHOR]

To improve the identification accuracy of coal gangue under the complex working conditions of pulverized coal and moisture adhesion on the surface, this paper studies the distribution difference of characteristic curves under five working conditions of different proportions of moisture and pulverized coal, and finds that moisture has a greater influence on gradient features, while pulverized coal has a greater influence on gray texture features. Then this paper studies the distribution of coarse texture and fine texture in coal and gangue, and finds that there are many fine textures and few coarse textures on the surface of gangue, while coal shows the opposite law. In addition, the ratio of pixels with large gray value to pixels with small gray value can reduce the occurrence of noncompliance with the above laws. Finally, through the combination of coarse texture, fine texture, and gray value difference, the relief feature is put forward. Compared with different features, the average feature overlap ratio proposed in this paper is lower, at 23.83%. Compared with different methods, this method has a higher identification rate under different working conditions, and the average identification accuracy rate is 89.59%, which is at least 13.93% higher than other methods. [ABSTRACT FROM AUTHOR]

The double-arch tunnel has been widely used in traffic engineering. As a key parameter of the partition wall, its thickness is closely related to the wall's bearing capacity. In this study, we use a double-arch tunnel passing through pulverized coal ash as an example and establish a numerical simulation model to study how the partition wall's thickness influences the tunnel's bearing capacity. The results show that the presence of the partition wall can significantly improve the stress state of the tunnel, meanwhile, excessive thickness of the middle partition wall can cause an increase of the arch crown stress. Compared to tunnels without a partition wall, when the thickness of the partition wall increases to 0.025 D, the arch load will increase by more than 30%. Furthermore, the results indicate that the bearing capacity is strongest when the thickness of the partition wall d is 0.0625 D. For tunnels without a partition wall, tensile stress concentration at the junction of the left and right holes will easily lead to cracking, and the right sidewall of the left hole will become the main compression part in the subsequent loading, resulting in complex tensile-compression-shear failure. For double-arch tunnels with a partition wall, the spandrel and the wall footing of the sidewall are the weak points of stress and are prone to damage, so these parts should be strengthened appropriately in design and construction. [ABSTRACT FROM AUTHOR]

The steel industry accounts, according to the International Energy Agency, for ~6.7% of global CO2 emissions, and the major portion of its contribution is from steelmaking via the blast furnace (BF) route. In the short term, a significant reduction in fossil CO2 emissions can be achieved through the introduction of bio-coal into the BF as part of cold bonded briquettes, by injection, or as part of coke. The use of bio-coal-containing residue briquettes was previously demonstrated in industrial trials in Sweden, whereas bio-coal injection was only tested on a pilot scale or in one-tuyere tests. Therefore, industrial trials replacing part of the pulverized coal (PC) were conducted. It was concluded that the grinding, conveying, and injection of up to 10% of charcoal (CC) with PC can be safely achieved without negative impacts on PC injection plant or BF operational conditions and without losses of CC with the dust. From a process point of view, higher addition is possible, but it must be verified that grinding and conveying is feasible. Through an experimentally validated computational fluid flow model, it was shown that a high moisture content and the presence of oversized particles delay devolatilization and ignition, lowering the combustion efficiency. By using CC with similar heating value to PC, compositional variations in the injected blend are not critical. [ABSTRACT FROM AUTHOR]

The combustion and fragmentation characteristics of wet coal slime particle are different from that of dried coal particle. In this paper, an understanding of the combustion process of wet coal slime particle through the combined results of the morphology characteristics, mass changes, and gas release pattern is provided. A tube furnace and high-speed camera were used to observe morphological changes of the combustion process of wet coal slime. For comparison, the mass change and gas release pattern of wet coal slime was monitored by a thermogravimetric analyzer and mass spectrometer (TG/MS). The four combustion stages of coal slime were observed for the first time: (1) drying and evaporation, (2) devolatilization and fragmentation, (3) volatile homogeneous combustion, and (4) char heterogeneous combustion. The water content in wet coal slime greatly affected the fragmentation of coal slime, it could build up a great internal pressure when evaporated, which caused the primary fragmentation to occur earlier and be more severe than traditional coals. The temperature and diameter of the slime were considered as factors for the occurrence of fragmentation and the level of it. A larger diameter with a higher furnace temperature resulted in a more severe fragmentation of the wet coal slime. The smaller coal slime at the lower temperatures did not experience the fragmentation stage. Here, the fragmentation and non-fragmentation zones of wet coal slime at different temperatures and different paticle diameters are given, which could be a guide for the combustion of coal slime in CFB(Circulating Fluidized Bed). Also, for larger diameters and lower setting temperatures, the ignition delay time and burnout time of wet coal slime became longer. The gas release pattern of wet coal slime during the combustion process was analyzed, and it was determined that it could be affected greatly by fragmentation. A model of the drying and evaporation stage of wet coal slime was established for the first time by using COMSOL Multiphysics. The results of the theoretical calculations show that there were two evaporation rate peaks of water when fragmentation occurred, which theoretically explained the early stage of the combustion process of wet coal slime, and the results were in agreement with the experiments. [ABSTRACT FROM AUTHOR]

Copyright of Chemical Engineering (China) / Huaxue Gongcheng is the property of Hualu Engineering Science & Technology Co Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The characteristics and influencing factors of gas production in CBM wells are analyzed based on the field geological data and the productivity data of coalbed methane (CBM) wells in the Zhengbei block, and then the favorable areas are divided. The results show that the average gas production of No. 3 coal seam CBM wells in the study area is in the range of 0~1793 m3/d, with an average of 250.97 m3/d; 80% of the wells are less than 500 m3/d, and there are fewer wells above 1000 m3/d. The average gas production is positively correlated with gas content, critical desorption pressure, permeability, Young's modulus, and Schlumberger ratio, and negatively correlated with fracture index, fault fractal dimension, Poisson's ratio, and horizontal stress difference coefficient. The relationship between coal seam thickness and the minimum horizontal principal stress is not strong. The low-yield wells have the characteristics of multiple pump-stopping disturbances, unstable casing pressure control, overly rapid pressure reduction in the single-phase flow stage, sand and pulverized coal production, and high-yield water in the later stage during the drainage process. It may be caused by the small difference in compressive strength between the roof and floor and the coal seam, and the small difference in the Young's modulus of the floor. The difference between the two high-yield wells is large, and the fracturing cracks are easily controlled in the coal seam and extend along the level. The production control factors from strong to weak are as follows: critical desorption pressure, permeability, Schlumberger ratio, fault fractal dimension, Young's modulus, horizontal stress difference coefficient, minimum horizontal principal stress, gas content, Poisson's ratio, fracture index, coal seam thickness. The type I development unit (development of favorable areas) of the Zhengbei block is interspersed with the north and south of the block on the plane, and the III development unit is mainly located in the east of the block and near the Z-56 well. The comprehensive index has a significant positive correlation with the gas production, and the prediction results are accurate. [ABSTRACT FROM AUTHOR]

Co-combustion in pulverized coal boilers is one of the best methods to achieve harmlessness, reduction and resource disposal for carbon-containing solid wastes. This work aims to study the effect of dried dust (DD) generated from CaC2 production on the combustion and slagging characteristics of Zhundong (ZD) coal blend. The combustion of ZD coal blend with different ratios (0%, 2.5%, 5.0%, 7.5%) of DD was conducted in a thermal gravimetric analyzer under air atmosphere. The ash fusion temperature tests and slagging experiments were carried out to understand the effect of the addition of DD on the slagging behavior of ZD coal blend. The results showed that the ignition and burnout temperatures of ZD coal showed different varying tendency with the blending ratio of DD increasing. Increasing the adding ratio of DD could raise the ash fusion temperatures of ZD coal blend. The addition of 5% DD promotes the formation of gypsum in deposited slags, and it also alters the chemical components of fine particles adhered onto the surface of molten particles. Meanwhile, in comparison with raw ZD coal blend, more Ca would combine into silicates in sampled slags. After the overall evaluation, a low blending proportion of DD (<5%) is suggested for pulverized boilers. [ABSTRACT FROM AUTHOR]

Herein, the ability of three explosion inhibitors (Al(OH)3, CaCl2, and NH4H2PO4) to prevent the occurrence of coal-dust explosions was compared at mass fractions of 30 wt% and 50 wt%. The effects of the three explosion inhibitors on the parameters characterizing the explosion intensity of pulverized coal, such as the maximum explosion pressure, pressure rise rate caused by the explosion, and the explosion index, were investigated. The results demonstrate that with increasing mass fractions of CaCl2 and NH4H2PO4, the explosion intensity of pulverized coal decreases. Notably, an increase in the mass fraction of Al(OH)3 did not reduce the explosion intensity. Furthermore, 50 wt% NH4H2PO4 content considerably decreased the values of both the maximum explosion pressure during a single explosion (Pex) and the maximum rate of explosion pressure rise in a single dust explosion experiment [(dp/dt)ex]. The maximum decrease in Pex after adding NH4H2PO4 was observed to be 62.79%, which is 35.87% and 47.70% higher than that obtained after adding CaCl2 and Al(OH)3, respectively. Furthermore, the maximum decrease in (dp/dt)ex after adding NH4H2PO4 when compared with the pulverized coal was 93.07%, which is 10.23% and 45.51% higher than that obtained after adding CaCl2 and Al(OH)3, respectively. Therefore, the order of the explosion suppression performance was as follows: NH4H2PO4 > CaCl2 > Al(OH)3. [ABSTRACT FROM AUTHOR]

Blast furnace is a multiphase counter‐current packed bed reactor that converts iron‐bearing materials such as lumps, sinter, and pellets into hot metal using metallurgical coke and pulverized coal. The quality of input materials has a significant impact on furnace performance, hot metal quality and steel plant economics. It is difficult for operators to identify the optimal settings required for efficient and safe operation based on their experience alone, given the large number of furnace parameters. A multiobjective optimization problem for maximizing furnace productivity (PROD) and minimizing fuel rate (FR) with constraints on hot metal silicon (HMSi) and temperature (HMT) is formulated and solved using a genetic algorithm. Machine learning (ML) models are developed for PROD, FR, HMSi, and HMT and tested with data from an industrial blast furnace. Pareto‐optimal solutions along with optimal settings for key manipulated variables are obtained. It is demonstrated that PROD and FR can be improved by ≈3–5% at steady state. The overall ML model‐based optimization framework can be used as part of a blast furnace digital twin system to operate the furnace efficiently in real‐time for the given quality of raw materials. [ABSTRACT FROM AUTHOR]

The basic national condition that is dominated by coal will not alter in the foreseeable future. Coal-fired boiler is the main equipment for coal utilization, and cyclone burner is a practical type of burner. There is a cyclone formation, a primary air duct inside the center air duct, and a secondary air duct. Introducing a small stream of pulverized coal gas or oil mist stream or gas directly into the reflux zone in the center duct ignites first a stable combustion and a small fluctuation of ignition pressure. In this paper, the variation of furnace temperature for cyclone pulverized coal burner corresponding to different excess air factors and the composition of gases such as O2, CO, CO2, and NOX produced by combustion were investigated using fluent software. A single cyclone pulverized coal burner from an actual coal-fired boiler is used, and a combustion zone applicable to the study of a single pulverized coal burner is established to study the actual operation of a single pulverized coal burner at different excess air coefficients. The findings indicate that the ignition position of pulverized coal combustion advances with decreasing α (Excess Air Factors); however, the length of the produced high-temperature flame gets shorter. As the value of α decreases, the burnout in the furnace decreases and the CO emission concentration increases, with a maximum CO mole fraction of 0.38% at α = 1.2 and a maximum CO mole fraction of 3.13% at the axial position when α decreases to 0.8. The furnace's concentration of NOX, the NOX emission level decreases significantly with decreasing α. The NOX mole mass increases gradually with increasing α, and in the bottom portion of the primary combustion zone, more NOX is produced. The concentration of NOX in the chamber changes significantly after α exceeds 1.0, and the NOX at the outlet surges from 417.25 ppm to 801.07 ppm, which is attributed to the increase in the average temperature of the chamber, which promotes the generation of thermophilic NOX. The distribution pattern of O2 mole fraction along the furnace height cross-section at different excess air factors is basically the same, with a maximum at the burner inlet and a gradual decrease in the O2 content as it enters the combustion chamber to react with the pulverized coal in a combustion reaction. The value of α = 0.8 when the air supply is obviously insufficient, the fuel cannot be fully combusted, and only a small amount of CO2 is produced. [ABSTRACT FROM AUTHOR]

To enhance the simulation efficiency of the EDEM discrete element numerical simulation software for coal powder mineral particles, experimental data on the rest angle of coal powder particles were collected as the response variable. Five parameters related to coal powder particles within the Hertz-Mindlin no-slip contact model were selected for investigation. Initially, the Plackett-Burman experiment identified three parameters: collision restitution coefficient, static friction coefficient, and rolling friction coefficient, significantly influencing the resting angle. Subsequently, the steepest ascent experiment determined the significant parameter ranges as follows: the collision restitution coefficient ranged from 0.20 to 0.40, the particle-particle static friction coefficient ranged from 0.30 to 0.50, and the particle-particle dynamic friction coefficient ranged from 0.06 to 0.10. Finally, the second-order regression model for the angle of repose and the saliency parameters was developed and optimized using the Box-Behnken experimental design. The following parameter combination was obtained: the collision recovery coefficient was 0.30, the particle-particle static friction coefficient was 0.49, and the particle-particle dynamic friction coefficient was 0.09. This study aimed to compare the angle of repose between the simulation experiment and the actual experiment. The relative error was only 1.02%, indicating that the simulation experiment achieved the optimal parameter combination. [ABSTRACT FROM AUTHOR]

The issue of pulverized coal in coalbed methane wells during the discharge and mining process spans all stages, and it is a key factor constraining the continuous and stable discharge and production capacity of coalbed methane. Among these stages, the single-phase water flow stage features a high incidence of pulverized coal. Consequently, this paper presents a physical simulation experiment within the propped fractures during the single-phase water flow stage. The results of this study reveal the following: (1) Within the propped fracture channel, when pulverized coal is deposited along the flow line without causing blockage, the front end of the deposition exhibits a strip-like dispersion, evolving into "block deposition", "flame-like accumulation", "linear accumulation", and "dispersed point-like accumulation". (2) Agglomerated fracturing fluid can effectively mitigate the permeability damage caused by pulverized coal to the propped fractures. Both the driving speed and particle size of pulverized coal significantly influence pulverized coal transportation. The injury rate of propped fracture conductivity increases with increasing driving speeds, while the output of pulverized coal first increases and then decreases with increasing driving speed. Moreover, larger pulverized coal particle sizes result in notably greater damage to propped fracture conductivity than smaller particle sizes. Correspondingly, larger particles exhibit significantly lower output of pulverized coal compared to smaller particles, and transportation and output time are prolonged for larger particles. These findings underscore the importance of particle size and driving speed in the transportation dynamics of pulverized coal. The research results provide a theoretical basis for developing strategies for the prevention and control of pulverized coal during the single-phase water flow stage, thereby offering substantial scientific and practical value for the economic and efficient development of coalbed methane. [ABSTRACT FROM AUTHOR]

This study emphasizes the potential role of coal gangue as an alternative fuel and oxygen-enriched combustion technology within twin-tank furnace precalciners in mitigating carbon emissions from cement production. The research primarily unfolds in two segments. Initially, the investigation addresses the influence of blending varying proportions of coal gangue under an air atmosphere on the internal temperature field and raw material decomposition components within the precalciner, aiming to discern the optimal blending ratio. Subsequently, the study simulates combustion under different oxygen-enriched atmospheres at the ideal coalgangue blending ratio, establishing the combustion patterns under these conditions. Although the mixed fuel prompts symmetry in the flow field and temperature field, the distinct combustion characteristics of coal gangue and coal powder, following a 20% coal gangue blend, lead to an accelerated mainstream velocity and abbreviated fuel residence time. Consequently, the exit temperature and CO2 concentration diminish with increasing blending content, reaching an optimal raw material decomposition rate of 91.12% within the precalciner when blended with 20% coal gangue. Furthermore, in oxygen-enriched combustion, as the oxygen content escalates, both the average temperature at the precalciner's exit and the raw material decomposition rate witness an upsurge, whereas the average CO2 concentration at the outlet experiences a decline. [ABSTRACT FROM AUTHOR]

Background: The combustion of coal, the world's most polluting form of energy, must be significantly curtailed to limit the global average temperature increase to well below 2°C. Since carbon pricing is politically constrained, alternative policies, such as compensating coal plant owners, for early closure are being considered. Methods: Germany is the only country to date to have implemented a reverse auction to give compensation payments for early coal retirement. We analyse the merits and demerits of Germany's policy, drawing comparisons with other countries that have phased out coal through other means. Results: While bilateral negotiations can lead to excessive compensation due to asymmetric information, a competitive auction can discover the true cost of closure and help allocate funds more efficiently and transparently. Germany's experience illustrates the practical necessity of adjusting auction design to ensure additionality, reduce the risk of gaming and manage the security of supply. Conclusion: While auctions have attractive properties in theory, in practice, their design must address these concerns to unlock the full benefits. Retirement auctions that deliver compensation payments can be a pragmatic policy option, particularly in countries where an incumbent coal lobby makes punitive measures such as carbon taxation hard to implement. However, where there is a concentration in coal plant ownership, auctions will not work and alternative policies, such as enhanced incentives for scrappage and repurposing of coal assets, could be used instead. In many coal-burning areas, the decline of coal is slowed down by long-term contracts that insulate coal-fired generation from competition. Compensation for early closure is a 'pay-to-break' mechanism which may be a politically feasible alternative to 'polluter-pays' policies such as carbon pricing. Competitive auctions can deliver efficient and transparent compensation payments for early coal closures relative to negotiations which suffer from asymmetric information. Ensuring that there is sufficient competition in a coal closure auction through design adjustments can ensure discovery of true closure costs. Shutting down coal-fired power plants can lead to fiscal savings in countries where coal-fired generation is supported by capacity payments. [ABSTRACT FROM AUTHOR]

In order to study the recycle of CO2 in the process of coal clean and efficient conversion, Xiwan coal with the particle size of 0 μm to 300 μm was continuously run in a pyrolysis-gasification industrial test device with a processing capacity of 36 t/d (referred to as "industrial test facility"). The material and heat balance, operation and product properties of industrial test device with CO2 were investigated. The results show that under the conditions of pyrolysis temperature of 600 °C, gasification temperature of 1000 °C and reaction pressure of 0.8 MPa to 1.0 MPa, after CO2 participates in the pyrolysis-gasification process, the industrial test device runs stably, and the steam consumption per ton of coal decreases by 5.38%, and the content of effective gas (CO + H2) in syngas increases from 74.74% to 79.63%, and CO content increases by 10.43%, and H2 content decreases by 5.54%, and syngas calorific value, carbon conversion rate and energy conversion efficiency increase. The yield of tar increases from 15.91% to 16.25%, the density decreases from 1.06 kg/m³ to 1.02 kg/m³, the kinematic viscosity decreases from 3.42 mm²/s to 2.70 mm²/s, the mass fraction of sulfur decreases from 0.20% to 0.15%, and the corresponding temperature of the same quality of tar fraction decreases by 10 °C to 30 °C. The mass fraction of aliphatic hydrocarbon in tar increases by 7.53%, the mass fraction of aromatic hydrocarbon decreases by 5.47%, and the mass fraction of other compounds increases by 15.98%. [ABSTRACT FROM AUTHOR]

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For a 300 MWe anthracite- and arch-fired boiler with biased-swirling-secondary-air (BSSA) technology, the distribution law of gas/solid two-phase velocity in the furnace is obtained with the help of a 1:10 cold modeling experiment bench, and the combustion and NOx formation characteristics in the furnace are revealed by numerical calculation. The results show that, with the increase of over-fire air rate, the reflux velocity in the reflux zone under the arch decreases continuously, and when the main air flow from the furnace arch reaches the staged air region from the vent air region, the position of particle flow in the primary air turn upward is advanced, and the utilization rate of the space in the lower furnace will decrease continuously. In the regions of vent air and staged air, when the over-fire air rate increases from 15% to 25%, the maximum vertical velocity decreases by approximately 2 times, and the downward depth of air flow from the furnace arch decreases significantly. When the over-fire air rate is increased from 10% to 25%, the thermal resistance between the primary air of the burner and the high-temperature flue gas in the furnace center increases, the ignition of the primary pulverized coal air flow is advanced, the flue gas temperature in the center of the lower furnace is decreased. As a result, with the increase of over-fire air rate, the combustible content of fly ash increases continuously. Especially, when the over-fire air rate increases from 20% to 25%, the combustible content of fly ash increases significantly. With the increase of the over-fire air rate, the high CO concentration region in the primary combustion zone expands, the reducing atmosphere is strengthened, the formation of NOx is effectively restrained, and the NOx emission concentration at the furnace outlet continues to decreases. In particular, when the over-fire air rate increases from 15% to 20%, the NOx emission concentration decreases greatly. After the swirling secondary air of the arch-fired boiler is biased, the setting of over-fire air rate is recommended to be 20%, and the NOx emission concentration and combustible content of fly ash are 694 mg/m3(O2 = 6%) and 7.32%, respectively. Compared with a traditional swirling arch-fired boiler, the combustible content of fly ash and NOx emission concentration are reduced by 46.8% and 34.1%, respectively. [ABSTRACT FROM AUTHOR]

The treatment of sewage sludge has become a global concern. Large amounts of sewage sludge can be disposed of by burning coal-mixed sludge. Thermogravimetric analysis and lab-scale combustion experiments in a drop tube furnace were utilized to study the combustion characteristics, pollutant emissions, and heavy metal migration during the co-combustion of coal and sewage sludge. The results showed that the blended fuels with a sewage sludge content less than 10 weight percent exhibited coal-like combustion characteristics. Additionally, the additional sewage sludge favored the ignition performance of blended fuels. When sewage sludge was added, the SO2 emissions rose to 76 mg/Nm3 under the 10% sludge condition—nearly three times higher than that of coal alone. While NOx emissions stayed mostly unchanged, HCl and HF emissions were very low. Meanwhile, Cr, Cu, and Ni migrated to the bottom ash, and their concentrations were all reduced with an increase in sewage sludge. Pb, Cd, Cr, Cu, Ni, and Hg migrated to the flue gas, mostly in the form of gaseous components. The results provide crucial information in the co-combustion of sewage sludge and coal, with implications in the development and improvement of large-scale, harmless, and resource-recovering techniques for waste sludge. [ABSTRACT FROM AUTHOR]

Estimating the source contribution to polycyclic aromatic hydrocarbons (PAHs) and nitropolycyclic aromatic hydrocarbons (NPAHs) in the atmosphere is necessary for developing effective disease control and pollution control measures. The NPAH-PAH combination method (NP method) was used to elucidate the contributions of vehicles and coal/biomass combustion to seasonal and long-term urban atmospheric particulate matter (PM)-bound Pyr and 1-NP concentrations in Kanazawa, Kitakyushu, Shenyang and Shanghai in the Western Pacific region from 1997 to 2021. Among the four cities, Kanazawa demonstrated the lowest Pyr concentration. The contribution of vehicles to Pyr before and after 2010 was 35% and 5%, respectively. The 1-NP concentration was reduced by a factor of more than 1/10. These changes can be attributed to the emission control from vehicles. Kitakyushu revealed the second-lowest Pyr and the lowest 1-NP concentrations. Coal combustion was found to be the main contributor to Pyr, while its contribution to 1-NP increased from 9% to 19%. The large contribution of coal combustion is attributed to iron manufacturers. Shenyang demonstrated the highest atmospheric Pyr concentration with its largest seasonal change. Vehicles are the largest contributors to 1-NP. However, coal combustion, including winter coal heating, contributed 97% or more to Pyr and more than 14% to 1-NP. Shanghai revealed the second-highest Pyr and 1-NP concentrations, but the former was substantially lower than that in Shenyang. Coal combustion was the major contributor, but the contribution of vehicles to Pyr was larger before 2010, which was similar to Kanazawa. [ABSTRACT FROM AUTHOR]

To effectively utilize ventilation air methane (VAM), it is proposed to pass it into the boiler of the coal‐fired power plant for mixed combustion. However, the different types of thermal coal utilized present distinct characteristics when mixed with VAM. In this paper, lignite, bituminous coal, and anthracite are selected to study the CH4 conversion rate, system ignition temperature, and NO emission characteristics of the VAM‐pulverized coal coupled system on a fluidized bed experimental platform. The experimental results show that the ignition temperatures of VAM are 748, 736, and 732 °C when the CH4 concentration is 0.25, 0.5, and 0.75%. After the addition of thermal coal, the ignition temperature decreased significantly. When the CH4 concentration is 0.25%, the ignition temperature of the lignite‐VAM system is the lowest, which is 450 °C. Anthracite has the strongest catalytic effect on CH4 combustion. When the heating rate is 5 °C /min, the reaction rate of CH4 is the fastest in the anthracite‐VAM coupled system. Under laboratory conditions, the peak NO concentration in the coal‐VAM coupled system was lignite > bituminous coal > anthracite at different CH4 concentrations, and the CH4 in VAM had a reducing action on the NO generated during mixed combustion, with a stronger reducing effect observed as the CH4 concentration increased. The results of this study can lay the foundation for the industrial application of the mixed combustion of VAM and thermal coal, and be of great significance for solving the practical problems caused by the change of boiler coal types. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract This paper presents the results of the development of stabilization measures aimed at the removal of zinc with the products of melting and accumulation of titanium in the hearth of a blast furnace. The relevance of the development and use in practice of such measures is due to the unstable fuel and raw materials conditions for the production of cast iron, when their stabilization is a complex and difficult task, as well as the need to extend the campaign of blast furnaces during the overhaul period. The negative effect of zinc oxides on the condition of the blast furnace shaft lining, accompanied by slab formation, and the overconsumption of specific coke consumption, which occurs when zinc circulates in the volume of the blast furnace, require measures to remove zinc from the smelting products. The article proposes such measures, which consist of flushing according to the proposed schedule during the operation of the blast furnace at planned blowing parameters and with the provision of the necessary thermal reserve. In order to lengthen the campaign of a blast furnace, one of the most common methods for protecting the hearth lining is the periodic introduction of titanium‐containing materials into the charge of blast furnaces. The entry of titanium oxides into the furnace, as a rule, is ensured by the use of concentrate or specially prepared ilmenite briquettes with a high titanium content as part of the sinter charge, which can be introduced directly into the composition of the blast furnace charge. The article analyzes the experience of using titanium‐containing materials as part of a blast furnace charge and formulates measures to intensify skull formation in the hearth.

Pulverized coal pyrolysis based on solid heat carrier has a huge advantage in high tar yield. In this study, pyrolysis experiments on pulverized coal were conducted in a lab-scale fluidized bed reactor at 650 °C, utilizing char as the solid heat carrier. The influence of mass ratio of char to coal (RATIO) was investigated. Results show that the incorporation of solid heat carrier of char significantly enhanced the primary pyrolysis reaction in coal pyrolysis, resulting in increasing yields of tar and gas but reducing one of char. The yield of tar maximally reached 148.80–262.22% of the Gray–King analysis value at the RATIO of 14.52 g/g. As the RATIO increased, the tar contained more light component content, indicating that incorporating solid heat carriers improved the tar quality. These findings offer significant insights for the design of fluidized bed pyrolysis unit utilizing char as solid heat carrier. [ABSTRACT FROM AUTHOR]

Pulverized coal (coal) possesses a layered structure similar to graphite and is a potential reinforcing filler. In this paper, ball milling is used to reduce the particle diameter of coal. The coal is modified with KH‐560 to obtain K‐COAL and prepared K‐COAL/styrene‐butadiene rubber (SBR) composites. In addition, carbon black (CB) is modified to obtain CB‐Si69, K‐COAL and CB‐Si69 are added to SBR in different ratios to prepare COAL/CB/SBR composites. The results show that the addition of K‐COAL can improve the vulcanization performance, thermal stability, and mechanical properties of SBR composites, but the reinforcing effect is weak. In the COAL/CB/SBR composites, the vulcanization and mechanical properties of the composites gradually increase with the increase of CB, while those of the thermal stability decrease. The tensile strength of the 10 phr COAL/30 phr CB/SBR composite is 24.1 MPa, which is elevated by 1105% and 205% compared with the pure SBR and 40 phr K‐COAL/SBR composites, respectively. The composites maintain high elasticity while the tensile strengths are greatly improved, and the mechanical properties are significantly enhanced. In conclusion, this paper provides a reference for the clean utilization of coal and shows new possibilities for finding new fillers to replace CB. [ABSTRACT FROM AUTHOR]

Numerical calculations of the innovative flue gas recirculation (FGR) system through an inactive coal pulverizer for a 40% load of the OP 650 boiler at the Jaworzno III Power Plant were carried out. The research was conducted to determine the effect of FGR on the formation of NOx, CO emissions, and low-NOx waterwall corrosion. Using numerical modelling, the influence of the place of injection of recirculated flue gas on the formation of NOx was also investigated. The tests were carried out based on data from the boiler monitoring system and calculation results using a 0-dimensional model. Modelling of the FGR was performed for five variants. FGR equalized the temperature in the furnace, eliminating temperature peaks in the burner belt. Moreover, FGR did not increase the CO content in the flue gas and reduced the O2 concentration in the area zone of pulverized coal combustion. For FGR systems, the emission of NOx below 200 mg/m3n for 6% O2 in dry flue gas was kept. This proves that the recirculation helps to meet the BAT (best available techniques) requirements for NOx emissions. It has also been shown that FGR does not pose a risk of low-NOx corrosion in the next 20 years. [ABSTRACT FROM AUTHOR]

In this study, a novel system which integrates solar thermal energy with membrane gas absorption technology is proposed to capture CO2 from a 580 MWe pulverized coal power plant. Technical feasibility and economic evaluation are carried out on the proposed system in three cities with different solar resources in China. Research results show that the output capacity and net efficiency of the SOL-HFMC power plant are significantly higher than those of the reference power plant regardless of whether a TES system is applied or not. In addition, the CEI of the SOL-HFMC power plant with the TES system is 4.36 kg CO2/MWh, 4.45 kg CO2/MWh and 4.66 kg CO2/MWh lower than that of the reference power plant. The prices of the membrane, vacuum tube collector and phase change material should be reduced to achieve lower LCOE and COR values. Specifically for the SOL-HFMC power plant with the TES system, the corresponding vacuum tube collector price shall be lower than 25.70 $/m2 for Jinan, 95.20 $/m2 for Xining, and 128.70 $/m2 for Lhasa, respectively. To be more competitive than a solar-assisted ammonia-based post-combustion CO2 capture power plant, the membrane price in Jinan, Xining and Lhasa shall be reduced to 0.012 $/m, 0.015 $/m and 0.016 $/m for the sake of LCOE, and 0.03 $/m, 0.033 $/m and 0.034 $/m for the sake of COR, respectively. [ABSTRACT FROM AUTHOR]

The objective of this study is to compare the ignition and burning characteristics such as burnout times of volatiles and char, and ignition mechanism of single pulverized coal particle burning in air (O2/N2) and oxy (O2/CO2) environments. An entrained flow reactor with photo detector has been employed for this study. This technique involves online monitoring of radiation emission from an individual coal particle. Individual particles of sub-bituminous or lignite coal particle with size in the ranges of 106-125 micron and 180-212 micron particles have been injected into an air (O2/N2) or oxy (O2/CO2) environment inside an entrained flow reactor. The oxygen concentration in the ambient gas is varied between 10%-50% by volume. The volatile and char burnout times have been obtained from time histories estimated from the radiation emitted by the particle. The results show an obvious increase in the burning rates of volatiles and char with increasing oxygen concentration. Further, when compared to N2 atmosphere, the burning rate and radiation intensity are found to be lower in CO2 atmosphere, especially at lower oxygen concentrations. An indication of the possible ignition mechanism has been outlined from the percentages of single and double peaks observed in the radiation emission histories. The complete experimental investigation shows that the burning rates of both volatiles and char are predominantly affected by the oxygen concentration, particle size and gas temperature. The theoretical results from a single particle model has been used to validate the trends and the combustion durations obtained from the present experimental study and is published as a separate manuscript. [ABSTRACT FROM AUTHOR]

The tracking of carbon and aerosol co-emissions is essential for environmental management. Satellite-based atmospheric synoptic observation networks provide large-scale and multifaceted data to help resolve emission behaviors. This study employs a comprehensive analysis of atmospheric dynamics, combustion byproducts, and aerosol characteristics around power plants. Strong correlations between Aerosol Optical Depth (AOD) at 500 nm and the column-averaged dry-air mole fraction of carbon dioxide (XCO2) were observed, revealing synchronous peaks in their emission patterns. The investigation into combustion completeness utilized metrics such as the ratio of carbon monoxide (CO)/XCO2 and Black Carbon Extinction (BCEXT)/Total Aerosol Extinction (TOTEXT). Discrepancies in these ratios across cases suggest variations in combustion efficiency and aerosol characteristics. Nitrogen dioxide (NO2) distributions closely mirrored XCO2, indicating consistent emission patterns, while variations in sulfur dioxide (SO2) distributions implied differences in sulfide content in the coal used. The influence of coal composition on AOD/XCO2 ratios was evident, with sulfide content contributing to variations besides combustion efficiency. This multifactorial analysis underscores the complex interplay of combustion completeness, aerosol composition, and coal components in shaping the air quality around power stations. The findings highlight the need for a nuanced understanding of these factors for effective air quality management. [ABSTRACT FROM AUTHOR]

The two categories of metallurgical coal are coal for coking and pulverized coal for injection in blast furnaces. The most significant characteristics of coking coal are those determined by technical analysis (yield of volatiles, ash content, etc.) and the metallurgical properties determining the quality of blast furnace coke. For pulverized coal, the important parameters are those determined by technical analysis, the calorific value, and the grinding index. Demand for metallurgical coal depends on the output of pig iron, which, in turn, depends on regional characteristics. Even in the era of the green agenda, metallurgical coal retains its benefits. Increase in the supply of metallurgical coal may be expected to continue until 2030. Most such coal comes from Australia, Russia, and Mongolia. In Russia, several large coal projects are underway (ELSI, Kolmar, Severnaya Zvezda). The goal is to export the coal, especially to Asia. Russian exports will increase by 20 million t per year in the near future, according to the authors' predictions. Global coal prices depend on production costs, which are at historically high levels. If global prices fall, the market will respond speedily, as high-cost suppliers are driven from the market, restricting supply, and global prices rise again. [ABSTRACT FROM AUTHOR]

Taking a 300-MWe arch-fired boiler as the research object, compared with original Babcock & Wilcox (B&W) combustion technology, the flow, combustion and NOx emission characteristics are comprehensively revealed under the novel biased-swirl-secondary-air combustion (BSSAC) technology with the help of cold-modeling experiments and numerical simulations. The results show that, for BSSA combustion technology, the dimensionless downward depth of the air flow from furnace arches is increased by 0.13, and the air flow fullness of whole the lower furnace is improved under the effect of burner secondary air near the water-cooled wall, vent air and staged air being injected step by step. The high-temperature reflux zone and gas reflux velocity under the furnace arch increase significantly, the ignition of primary pulverized coal air flow is advanced, and the combustion path of pulverized coal particles increases. The combustible content of fly ash decreases by 32.4%. At the same time, the ignition process of pulverized coal air flow near the center of the furnace is in a strong reducing and low oxygen atmosphere, and the multi-stage effective air supply is obtained in the downward process of pulverized coal combustion. The NOx emission concentration at the furnace outlet is reduced from 824 to 694 mg/m3 (O2 = 6%). [ABSTRACT FROM AUTHOR]

This research aims to analyze the techno-economic and environmental aspects of retrofitting carbon capture and storage (CCS) technology on the existing 330 MWe pulverized coal (PC) power plant. Modeling simulations on existing PC and retrofitting PC CCS with variations in biomass co-firing (wood pellet) were carried out using the Integrated Environment Control Model (IECM) version 11.5 software. An amine-based post-combustion capture was used in this study. Coal and biomass co-firing at PC CCS reduce the net power output and thermal efficiency. Carbon neutrality occurs at 10% biomass co-firing on PC CCS. There was a 164% increase in the levelized cost of electricity (LCOE), from 0.0487 USD/kWh on PC to 0.1287 USD/kWh on PC CCS. A sensitivity analysis of fuel prices shows that at a fuel price of 25 USD/t, the LCOE of PC CCS is 0.0953 USD/kWh or higher than Indonesia's national weighted LCOE of 0.0705 USD/kWh. The LCOE of PC CCS can be lower than the national weighted LCOE when the carbon price is higher than 80 USD/t CO2. [ABSTRACT FROM AUTHOR]

Water scarcity is a significant global issue caused by the prolonged disregard and unsustainable management of this essential resource by both public and private bodies. The dependence on fossil fuels further exacerbates society's bleak environmental conditions. Therefore, it is crucial to explore alternative solutions to preserve our nation's water resources properly and promote the production of biofuels. Research into the utilization of E. crassipes to remove heavy metals and generate biofuels is extensive. The combination of these two lines of inquiry presents an excellent opportunity to achieve sustainable development goals. This study aims to develop a sustainable wastewater treatment system and generate biohydrogen from dry, pulverized E. crassipes biomass. A treatment system was implemented to treat 1 L of industrial waste. The interconnected compartment system was built by utilizing recycled PET bottles to generate biohydrogen by reusing the feedstock for the treatment process. The production of biological hydrogen through dark fermentation, using biomass containing heavy metals as a biohydrogen source, was studied. Cr (VI) and Pb (II) levels had a low impact on hydrogen production. The uncontaminated biomass of E. crassipes displayed a significantly higher hydrogen yield (81.7 mL H2/g glucose). The presence of Cr (IV) in E. crassipes leads to a decrease in biohydrogen yield by 14%, and the presence of Pb (II) in E. crassipes leads to a decrease in biohydrogen yield of 26%. This work proposes a strategy that utilizes green technologies to recover and utilize contaminated water. Additionally, it enables the production of bioenergy with high efficiency, indirectly reducing greenhouse gases. This strategy aligns with international programs for the development of a circular economy. [ABSTRACT FROM AUTHOR]

The present research shows the combustion characteristics of different specific gravity fractions of high ash thermal coal. Coal with different mean specific gravity (SGM) ranging from 1.25 to 2.0 was produced using the float–sink experiment. All SGM coals were characterized with proximate analysis, ultimate analysis, higher heating value, ash analysis, Brunauer–Emmett–Teller analysis and Fourier-transform infrared spectroscopy (FTIR). Combustion experiments were performed with thermogravimetric analysis to identify the impact of SGM. Experimental results inferred that ignition temperature ranged from 285 to 408 °C as SGM varied from 1.25 to 2.0. The combustion rate of 1.25 SGM coal was found to be the highest due to the strong or moderate presence of hydrocarbons like alkane, alkene, aldehyde and alcoholic, as observed from FTIR. Activation energy ranged from 121.81 to 54.60 kJ/ mol as SGM of coal increased from 1.25 to 2.0. Thermodynamic analysis inferred that 1.65 SGM coal had the highest ΔS (− 158.21 J/mol. K) and minimum ΔH (48.93 kJ/ mol), inferring ease of decomposition and higher combustion reactivity. [ABSTRACT FROM AUTHOR]

Hydrogen energy is an important carrier for energy terminals to achieve green and low-carbon transformation. Hydrogen, as a carbon-free fuel, has great research and development value in the field of thermal power generation. This article proposes a solution for the stable combustion of coal powder using Oxy-hydrogen Gas ignition technology. An Oxy-hydrogen Gas flame injection coal powder combustion testing device was constructed to experimentally study the temperature distribution in the combustion chamber under Oxy-hydrogen Gas ignition technology, with primary air coal powder concentrations of 0.27, 0.32, and 0.36 (kg coal powder/kg air), as well as the concentration changes of volatile CO emissions during the ignition of coal powder using both Oxy-hydrogen Gas and CH4 flames. The sensitivity of the NO generation during coal gasification combustion under the Oxy-hydrogen Gas ignition was simulated and analyzed. The results show that at a coal powder concentration of 0.32 (kg coal/kg air) and an Oxy-hydrogen Gas flow rate of 2.1 L/min, the combustion effect of coal powder is the best, and the highest combustion chamber temperature can reach 1156 K; when the concentration of coal powder varies within a range from 0.32 to 0.27, the combustion chamber temperature can be maintained at around 850K, achieving stable combustion conditions for coal powder. The only product generated by the Oxy-hydrogen Gas combustion is high-temperature water vapor, which helps the rapid gasification of coal powder and releases a large amount of volatile CO, which is beneficial for the ignition and stable combustion of coal powder. [ABSTRACT FROM AUTHOR]

Numerical and experimental studies were conducted to study the nonlinear phenomena of a 1000 MW ultra-supercritical four-corner tangential pulverized coal boiler. In this paper, (1) a 3D model of a furnace with a symmetrical structure was established to analyze the asymmetric flow phenomenon and multi-solution phenomenon of flow for multiple timepoints under the same boundary conditions. (2) The visual experiment verified that the flow in the furnace also behaved asymmetrically. (3) On the basis of correctly predicting the nonlinear law, the "diagonal start up" method and the "sequential start up" method are proposed. (4) An uneven coefficient of velocity distribution M, deviation coefficient of flue gas mass flow rate Eq and gas temperature deviation coefficient ET are proposed to quantitatively analyze the degree to which the actual tangent circle deviates from the ideal tangent circle. The tangent circle under the "sequential start up" method is the closest to the ideal, which can reduce the thermal deviation of the furnace outlet from 67 K under the "simultaneous start up" method to 41 K. In this paper, the initial steady-state flow field in the furnace is established by using the initial value sensitivity of the nonlinear system through different burner-opening methods, so as to reduce the thermal deviation at the furnace outlet and achieve the purpose of accurate control. [ABSTRACT FROM AUTHOR]