Ash Accumulation Research Articles

Incipient fault detection for the spindle bearing of a cement grinding machine based on vibrational resonance

Abstract The spindle bearing of a circulation fan is an important component of a cement grinding machine. In addition to the faults on the spindle bearing, impeller wear and ash accumulation may cause dynamic unbalance and complex vibration interference as noise, which decreases the accuracy of fault detection based on vibrational signals and traditional signal processing-based methods at the early stage of a bearing fault. To address this issue, this paper presents a new fault detection method for the spindle bearing by utilizing extra injected noise and vibrational resonance. To enhance the fault signature and resonance performance, the nonlinear system of the traditional vibrational resonance is replaced by a new hybrid steady-state system, and the underdamped term is considered in the new system. The proposed system provides more possibilities to achieve resonance by adjusting the system parameters and overcomes the limitations of output saturation caused by the classical bistable system. The proposed method is validated by analyzing the collected vibration signals from a spindle bearing of a circulation fan in practice and is compared with other noise-elimination fault detection methods. The results demonstrate the effectiveness and superior performance of the proposed method.

Identification of water-cooled wall ash accumulation based on AWGAM-YOLOv8n

Identifying the ash accumulation generated on the water-cooled walls of the waste incinerator is essential for the cleanup by the robotic arm. This paper improves a new algorithm based on YOLOv8n, which can identify the ash accumulation position on the water-cooled wall quickly and accurately. Firstly, the multi-scale fusion image enhancement algorithm is used to improve the sharpness and contrast of the image and enrich the details of the image. Secondly, the backbone feature extraction network of YOLOv8n is replaced by Mobilenetv3 network, which reduces the parameters in the model greatly. Finally, this paper improves a new attention mechanism AWGAM (Add Weight Global Attention Mechanism) based on GAM (Global Attention Mechanism), which can better integrate the feature information between different dimensions and improve the learning ability of the model. AWGAM is added to the backbone of the model. The experimental results show that compared with the original YOLOv8n model, the improved YOLOv8n model has 59.9% fewer parameters, 4.4% higher precision, 8.8% higher recall, 3.2% higher mAP50 (mean Average Precision) and 8.8% higher mAP50-95. This model has made remarkable progress on the basis of the original algorithm, and has strong competitiveness compared with other advanced target detection models. The lightweight and high accuracy of ash accumulation detection offered by the proposed model presents promising applications in ash accumulation detection tasks of water-cooled walls.

Порівняння ущільнюваності асфальтобетонної суміші із золою-винесення та вапняковим наповнювачем

Introduction. In Ukraine, about 30 % of all electricity is generated from the combustion of solid fuels — coal, shale, peat. In our country, there are about 15 operating thermal power plants that generate about 5 – 6 million tons of ash and slag waste per year as a secondary product. Thus, the fuel and energy complex waste generated in the furnaces of thermal power plants is a huge accumulation of ash in the form of dusty residues and lumpy sludge, as well as various ash and slag mixtures. These products of high-temperature processing (1 200 – 1 700 ºС) of the mineral part of the fuel are widely used in many countries of the world and, given the global trend towards an increase in the share of the secondary market for the use of waste, it is necessary to predict an increase in the rate of their processing in Ukraine. Problem Statement. The road construction industry is one of the strategic industries of Ukraine, and the issue of quality and availability of basic building materials for road construction is particularly acute now, which is directly related to its high material intensity. The known reserves of high-quality raw materials that could be used as asphalt concrete components are constantly decreasing, so it is necessary to look for alternative sources of raw materials for construction materials and explore the possibility of their use. In this regard, the most effective use of local raw materials is the use of industrial waste, which can be one of the solutions to the problem of lack of raw materials of inorganic origin.

Research on ash accumulation surface measurement methods based on the dot laser principle

Dust collectors are essential environmental protection equipment in thermal power plants. However, in recent years, collapses caused by excessively high material levels in the ash hopper in dust collectors have increased frequently, resulting in serious casualties and significant economic losses. The level gauge of the ash hopper is a crucial device for detecting the material level in the ash hopper and plays a vital role in preventing the ash hopper from collapsing due to excessive material load. However, level gauges of the ash hopper currently in use have various problems. Laser-ranging technology is characterized by concentrated energy, a small divergence angle, and the ability to penetrate dust. We have proposed a new material-level measurement method based on the dot matrix laser ranging principle. This method utilizes dot-matrix laser ranging and visualizes the optimized measurement data to ultimately derive information about the material surface's morphology and level. A physical hopper model is used to conduct verification experiments on various material surface morphologies, material levels, and the material hanging on the hopper wall. The results indicate that this method can accurately identify the material level and the material hanging on the hopper wall, preventing false alarms due to “false material levels.”

Axial compression performances and bearing capacity prediction of self-compacting fly ash concrete filled circle steel tube columns

To solve the problem of a large amount of fly ash accumulation and study the axial compression and bearing capacity prediction of the self-compacting fly ash concrete filled circle steel tube (SCCFST) columns, eight specimens are designed to explore the impact of concrete strength grade, internal structural measures, and additional parameters. The stress, progression of deformation, and failure mode of each specimen are observed during the loading process. The load–displacement curves, load-strain curves, characteristic load and displacement, ductility, and stiffness degradation are analyzed. The findings revealed that shear deformation occurred predominantly in the middle and upper portions of the steel tubes. Enhancing the strength of the concrete or adopting internal structural measures could increase the bearing capacity and ductility of the specimens. The peak load and ductility could be increased by up to 17.6 and 53.6%, respectively. The proposed unified calculation equation for the axial compression bearing capacity of SCCFST columns demonstrates notable reliability and precision. Furthermore, these tests offer valuable references for the engineering application of various forms of SCCFST columns, which are of significant importance in practical engineering.

Study on impact resistance performance of MSWIFA-based low-carbon fiber-reinforced concrete

The accumulation of carbide slag (CS), red mud (RM), and municipal solid waste incineration fly ash (MSWIFA) has led to significant environmental pollution issues, necessitating urgent resource utilization. Building upon the previously developed CS-MSWIFA synergistic activation RM-slag cementitious system, this study aims to further incorporate iron tailings sand and polypropylene fibers to prepare fiber-reinforced concrete. The systematic investigation focuses on the influence of cementitious material types, aggregate types, fiber shapes, lengths, and dosages on the impact resistance of concrete. Furthermore, an impact damage evolution equation and life prediction model were developed based on the two-parameter Weibull distribution. Results indicate that the type of cementitious material and aggregate has minimal influence on the impact resistance of concrete, while the addition of fibers significantly enhances its impact resistance, shifting the failure mode from brittle to ductile. Mesh polypropylene fibers with a length of 12 mm and a volume dosage of 1.0 % demonstrate excellent impact resistance, with initial and final crack numbers reaching 78 and 105, respectively. This represents an increase of 136.4 % and 200.0 % compared to the control concrete without fibers. The findings of this study offer new avenues for the resource utilization of solid waste and provide theoretical foundations and technical support for the potential application of solid waste based fiber-reinforced concrete in structural engineering.

Effect of fly ash on mechanical properties and microstructural behaviour of injected moulded recycled polypropylene composites

The global challenges of plastic waste and fly ash accumulation demand innovative recycling solutions. In Malaysia, the consumption of 11.2 million tonnes of coal annually generates approximately 2 million tonnes of fly ash, while the recycling of Polypropylene (PP) is hindered by thermo-oxidative and shear-induced degradation during mechanical recycling, resulting in reduced mechanical properties. This study addresses these issues by fabricating recycled PP composites incorporating varying fly ash contents, using a single cycle of mechanical recycling with extrusion and injection moulding methods. The composites were comprehensively tested for tensile, flexural, and compressive strengths, as well as microstructural behaviour. The results reveal a complex relationship between fly ash content and mechanical performance: while tensile strength decreases with increasing fly ash, flexural strength and strain peak at 5 % and 9 % fly ash, respectively. Compressive strength also shows a slight increase up to 7 % fly ash, indicating an optimal range for enhancing mechanical performance. Furthermore, mathematical models were proposed to predict the mechanical properties of rPP – fly ash composites, providing a valuable tool for future material design. These findings demonstrate that optimization of fly ash content can mitigate the effects of polymer degradation, offering a sustainable solution to improving the mechanical performance of this composite.

Tuff deposits as preservational context for a Miocene continental mammal assemblage from Patagonia, Argentina

The CO tuff is one of the volumetrically largest volcaniclastic events so far recorded in the Early-Middle Miocene Santa Cruz Formation (Patagonian Argentina). It represents aeolian processes, related with westerlies, that reworked and transported enormous quantities of volcanic ash from the Andes into the continental interior that accumulated in fluvial floodplain deposits. This volcanic event generated a major environmental change at ∼17 Ma (Burdigalian) and hostile living conditions for the biota of the area, at least during the time of deposition. We performed here a comprehensive study including taxonomic, sedimentological, and taphonomic aspects of the mammal assemblage recovered from this tuff deposit. The assemblage is constituted by representatives of Microbiotheria, Paucituberculata, Folivora, Cingulata, Rodentia, Notoungulata, and Litopterna, reflecting a wide mammalian diversity. The formation of the assemblage can be linked to a normal attritional model, in which the death of the individuals and subsequent deposition and burial of their remains would have occurred gradually over time, simultaneously with the accumulation of volcanic ash, at the place of death or very close to it. The time between the death and burial would have been relatively short, in accordance with the rapid and continuous influx of volcanic ash to the depositional environment. This multidisciplinary study allows us to interpret and reconstruct the possible taphonomic pathways of the mammal assemblage and to provide novel information on this particular preservation context linked to volcanically-influenced fluvial environments.

Investigating the impact of humidity on potential-induced degradation (PID) in photovoltaic modules with ash accumulation

Investigating the impact of humidity on potential-induced degradation (PID) in photovoltaic modules with ash accumulation

Not only domestic spaces: dismantling short‐term occupations in Level 497D of Cova Gran de Santa Linya (Pre‐Pyrenees, Spain)

ABSTRACTThe Early Upper Paleolithic Level 497D of Cova Gran (Pre‐Pyrenees, Spain) comprises large assemblages of lithics, fauna, hearths, ash accumulations and well‐preserved refitting sequences. This provides exceptional information to analyze spatial patterns and deepen our understanding of the socio‐economic behavior of these human groups. This large interdisciplinary dataset has allowed us to carry out a detailed spatial study based on density analysis, geostatistics, fabric analysis and orientation techniques, revealing a structuring of the activities performed within the rock shelter. The distribution and accumulation of lithic artifacts, fauna and refits, and their association with the 10 hearths and ash accumulations, show that different types of activities were developed at the site, as well as showing the different uses of the hearths. 497D is a palimpsest where several short‐term occupations and/or activities could have occurred in a relatively short period of time, avoiding prolonged exposure to biotic and abiotic post‐depositional factors that could have significantly disturbed this well‐preserved assemblage. This level shows a place visited several times in relation to the development of specific activities, with movements throughout the landscape for the exploitation of local and regional resources, and less so its use as a domestic space. This implies that the central settlement, or dwelling space, would have been located somewhere other than Cova Gran.

Study on the influence of outlet diameter on the out-field pressure action characteristics of pulse detonation cleaning device

Pulse detonation cleaning technology is an efficient cleaning technology that is used inert shock waves generated by decoupling the detonation to remove ash and deposits. And it has great advantages in the field of furnace cleaning. In order to investigate the pressure distribution characteristics outside the detonation cleaning device and to explore the effect of the device outlet diameter on the pressure distribution characteristics, numerical simulations and experimental studies of pulse detonation cleaning device with using propane-air as the fuel has been carried out. The numerical simulation and experimental study on pulse detonation cleaning device by using propane-air as the fuel has been carried out. The results show that: as the propagation distance increases, there is a trend for the out-field arc shaped shock wave to transform into plane wave, and the applied pressure tends to be similar from the axis outward, and the time it acts on the ash accumulation surface also tends to be similar. When the external shock wave acts on the ash accumulation surface of the non-convective tube bundle, except for the positive reflection at the axial opposite position, which generates one pressure peak, the other positions mainly generate two pressure peaks due to oblique reflection. The ratio (diameter ratio) between the diameter of the tail outlet and the diameter of the detonation chamber is 1, the pressure peak of inert shock wave in the out-field is the largest. Increasing or decreasing the out diameter of the tail will weaken the action of the inert shock to different degrees. For diameter ratio smaller than 1, the pressure peak of the inert shock increases with increasing diameter ratio, while for diameter ratios larger than 1, decreases with increasing diameter ratio.

Optimization of PV module ash accumulation prediction based on an improved vulture algorithm

Abstract In this research, an ash accumulation prediction model based on the Improved Bald Eagle Algorithm (IBES) optimization is proposed, and a least-squares support vector machine (LSSVM) is used to investigate the correlation between climatic parameters and the quantity of ash deposition on PV panel surfaces. Ash deposit affects PV panel output power over time and is influenced by meteorological factors. Following a thorough selection procedure, meteorological variables like wind speed and rainfall are used in the model to forecast the amount of ash that will accumulate on the slab. The original condor method was prone to local optimum convergence and had a slow convergence rate. These weaknesses are addressed by the optimal selection of the next iteration, which introduces the Cauchy variation operator to mutate the population’s optimal individuals. The optimization parameters of the revised algorithm are incorporated into the model and results are compared to models of other optimization algorithms. The outcomes demonstrate that the IBES-LSSVM ash accumulation prediction model has a higher degree of fit and a reduced prediction error.

Numerical investigation on ash accumulation characteristics of serrated spiral finned tube heat exchanger in waste heat utilization

In this study, a comprehensive loose fouling model is established to investigate the fouling characteristics of fly ash on serrated spiral finned tube heat exchangers. This model considers the energy change during particle collision, the velocity change after particle rebound and slip, and the amplification of fouling time under mixed particle sizes. The results show that the fouling position, morphology, and height obtained by the theoretical model agree well with the experiments. Besides, the serrated spiral fin is the main fouling position due to its high fin ratio and the strong disturbance effect. The 5 μm particles have the highest deposition rate, and fine particles tend to adhere to the second row of finned tubes due to the consumption of initial kinetic energy by the first row. With an increase in fin height by 6 mm, the deposition rate only increases by 1.2 %, while an increase in sawtooth height by 5 mm results in a deposition rate increase of 14.3 %. When the flue gas velocity is less than 7 m/s, finned tubes arranged in a staggered configuration provide the best combination of heat transfer, flow resistance, and anti-ash accumulation performance.

Оценка золошлаковых отходов как источника загрязнения окружаюшей среды и источника вторичного сырья

Introduction. Currently, more than 500 million tons of fly ash have been accumulated on the territory of the Republic of Kazakhstan, the volume of which will increase to one billion tons by 2030. Such accumulation of fly ash in storages creates a powerful anthropogenic impact on the biogeocenosis. A significant proportion of these man-made materials are formed during the burning of Ekibastuz coals. There is practically no processing of ash and slag waste on an industrial scale. For various reasons, ash dumps are not used in Kazakhstan, because the physico-chemical properties have been very poorly studied, in addition, during their processing, other wastes or ash dumps unsuitable for use are obtained from these wastes, because they contain a lot of unburned coal. As of 01.01.2020, the share of recycled, reused, burnt ash and slag waste in Kazakhstan amounted to 0.7%. The relevance and significance of this problem is due to the fact that man-made waste from CHP plants is not sufficiently processed, and current ash waste accumulates and occupies huge areas, which removes them from land use. Knowledge of the chemical composition of the ash will allow it to be used to obtain building materials. The purpose of this work is to study the properties of ash and slag waste during the burning of coal from the Ekibastuz deposit in Kazakhstan, to assess them as a source of environmental pollution, to determine the possibility of obtaining demanded building materials from them. Research methods. To determine the phase composition of the studied material, an upgraded diffractometer DRON-3M on CuKa radiation with software was used. Radiographs of the sample were obtained in the range of 2° (angles) from 10 to 70°. The chemical composition was determined using an energy dispersion spectrometer “EDX-8000”. Micrography of fly ash was taken on a scanning electron microscope Superprob-733. Research materials. Ash and slag waste from the burning of coal from the Ekibastuz deposit in Kazakhstan. Research results and discussion. The physical characteristics of ash have been established: specific surface area – ~200 m2/kg, true density – 2.1 g/cm3, bulk density – ~780 kg/m3. Fractional composition: the highest content of particles with a size of 100 microns (25.8%), 80 microns (12.12%), 50 microns (21.46%) and 45 microns (21.38%); at the same time, unburned carbon is concentrated in large fractions, glass phase – in small ones. Analysis of the chemical composition of Ekibastuzky ash allowed to find out the composition of coal minerals. The main components are silicon and aluminum oxides, and there is also a large amount of iron oxide. Knowledge of the chemical composition of ash allows it to be used in the production of building materials. Conclusion. The results of the conducted studies have shown the possibility of using ash and slag waste as secondary raw materials in the construction of road materials in order to reduce the anthropogenic load on the environment.

Micron-Smooth, Robust Hydrophobic Coating for Photovoltaic Panel Surfaces in Arid and Dusty Areas

Photovoltaic (PV) power generation is a clean energy source, and the accumulation of ash on the surface of PV panels can lead to power loss. For polycrystalline PV panels, self-cleaning film is an economical and excellent solution. However, the main reasons why self-cleaning coatings are currently difficult to use on a large scale are poor durability and low transparency. It is a challenge to improve the durability and transparency of self-cleaning thin films for PV panel surface against ash accumulation. Therefore, in this paper, a resin composite film containing modified silica components was designed and synthesized, mainly by the organic/inorganic composite method. A transparent hydrophobic coating with nano-micro planar structures was constructed, which primarily relies on the hydrophobic properties of the compound itself to build the hydrophobic oleophobic coating. The layer has a micrometer-scale smooth surface structure and high transparency, with a 0.69% increase in light transmittance compared with uncoated glass, and the durability is good. It is mainly applied to the surface of photovoltaic devices, which can alleviate the dust accumulation problem of photovoltaic panels in arid, high-temperature, and dusty areas and reduce the maintenance cost of them.

Effect of Fly Ash on the Mass Transfer Performance of CO2 Removal Using MEA and DEA Solutions in a Packed Tower

The accumulation of uncollected fly ash from flue gas in post-combustion CO2 capture processes is a significant concern in current coal-fired power plants due to its potential impact on the performance of CO2 absorbent and absorption towers. In order to determine the effect of fly ash on the mass transfer performance of CO2 absorption into monoethanolamine (MEA) and diethanolamine (DEA) aqueous solutions, experimental studies were carried out using a small-sized packed tower equipped with θ-ring random packing. These studies were conducted under various operating parameters, including solution temperature, liquid/gas ratio (L/G), packing height, and fly ash concentration. The results show that the effect of fly ash on the outlet CO2 concentration was primarily observed during the initial stages of the experimental process. Moreover, the presence of fly ash leads to a reduction in the volumetric overall mass transfer coefficient (KGav) when using MEA and DEA solution, and increasing the fly ash concentration further exacerbates this negative impact. However, the effect of fly ash on the reduction in KGav is not significantly related to its chemical composition but rather depends on the operational parameters. With increasing solution temperature, liquid/gas ratio (L/G), and packing height, the KGav values for different solutions exhibit an upward trend. The negative effect of fly ash on KGav remains relatively stable for MEA as solution temperature and packing height increase. Compared to MEA, fly ash has a greater negative effect on DEA solution under the same experimental conditions. The analysis reveals that the detrimental effect of fly ash on KGav primarily stems from its ability to alter the distribution state of the absorption liquid within the packed tower.

The specifics of the content of chemical elements and ash in the leaves of ornamental plants in an urban environment

The content of sulfur, nitrogen, phosphorus, ash content in the leaves of annual and perennial species and varieties grown in urban conditions near highways and industrial enterprises of the cities of the Novosibirsk region: Iskitim, Berdsk, Koltsovo, Evsino, Sovetsky district of Novosibirsk was studied. Indications of these substances were determined in the leaves of Hemerocallis hybrida, Iris hybrida, Hosta lancifolia, H. decorata, Salvia splendens, Tagetis patula, Senecio cineraria Malva hybrida, Gatsania hybrida, Alyssum hybrida. The individual features of the accumulation of nutrients and ash in aboveground vegetative organs have been revealed. It was noted that the level of nitrogen concentration and ash content in the leaves of floral and ornamental plants exceeded the values of phosphorus and sulfur by 6–11 times. An increase in the concentration of chemicals and ash in plant leaves in an urban environment has been established.

Synthesis of a high-iron fly-ash-based Na-X molecular sieve and its application in the adsorption of low concentration of CO2.

In addressing the environmental challenges posed by the accumulation of fly ash (FA), efforts have been geared towards its high-value utilization. By the use of high-iron FA as a raw material, a high-iron fly-ash-based Na-X molecular sieve was successfully synthesized by hydrothermal method. We combined pretreatment methods such as high-temperature calcination, acid leaching and alkali fusion activation. The as-synthesized product was used for the adsorption of a low concentration of CO2, and the adsorption data were fitted by a physical model. The changes in iron content in pretreatment and molecular sieve synthesis were revealed by SEM-mapping, UV-Raman and UV-Vis. The results showed that the pretreatment process reduces the iron content from 32.3% to 13.3%, and converts the inactive phases to active phases, with n (SiO2/Al2O3) = 4.94. The activated product was transformed further to a Na-X molecular sieve using a hydrothermal method. The product has a single crystal phase and octahedral crystal structure. Its specific surface area was 646.634 m2 g-1, and micropores were distributed between 0.46 nm and 0.71 nm, with a mesoporous phase of 4.6 nm. When used to adsorb a low concentration of CO2, the Na-X molecular sieve has a high adsorption capacity of 3.70 mmol g-1, which reaches 95.11% that of the commercial Na-X molecular sieve. The adsorption breakthrough time and adsorption capacity decreased with an increase in temperature. The adsorption kinetics were consistent with the Bangham model for surface pore adsorption and Weber-Morris model for internal diffusion. During the synthesis process, iron was converted from highly dispersed iron oxide to four-coordinated framework iron. Thus, this paper paves a path for the high-quality transformation and utilization of high-iron fly-ash.

DETERMINATION OF MODULUS OF ELASTICITY OF ASPHALT CONCRETE WITH FLY ASH USING THE WITCZAK MODEL

Summary. In Ukraine, about 30% of all electricity is produced by burning solid fuels - coal, shale, and peat. In our country, there are about 15 operating thermal power plants, which generate about 5-6 million tons of ash and slag waste as a secondary product per year. Thus, the waste of the fuel and energy complex, which is formed in the furnaces of thermal power plants, is a huge accumulation of ash in the form of dust-like residues and lumpy sludge, as well as various ash-slag mixtures. These products of high-temperature processing (1200-1700 ºС) of the mineral part of the fuel are widely used in many countries of the world, and taking into account the global trend of increasing the share of the secondary market for the use of waste, it is necessary to predict an increase in the rate of their processing in Ukraine as well. Problems. In Ukraine, as a filler, the material obtained by crushing carbonate rocks is used as a filler, which is established in DSTU B B.2.7-121. At the same time, as a result of burning coal, millions of tons of dust-like waste - fly ash - are generated at power-generating enterprises of Ukraine. In terms of indicators, this material approaches the requirements for filler according to DSTU B V.2.7-121 and can be used for the production of asphalt concrete mixtures.

Numerical investigation of honeycomb channel design: Effect of rounded corners on selective catalytic reduction of NO

In this work, single-channel models are established to investigate the effect of rounded corners on overall performance of honeycomb catalyst with various channel geometries and cell densities (Ncell). As channel shape factor (γ) increases, pressure drops all rise slowly at low γ (0 ∼ 0.5) and increases dramatically when γ > 0.5, aligning with monolith voidage and hydraulic diameter variations. Hexagon-channel catalysts with open corners exhibit the smallest pressure drop increase (17.3 %), while triangle-channel catalysts with acute corners show the highest rise (100.1 %). The increase in Ncell leads to a similar rise (43 %) in pressure drop. NO conversions decrease with γ due to reduced external surface area, with maximum conversions observed for triangle-channels (low γ) and hexagon-channels (high γ). Increasing Ncell enhances NO removal and mitigate rounded-corner effect on conversion (4.5 % to 1.2 % reduction). Based on that, a design strategy suggesting γ = 0.5 is proposed to eliminate ash accumulation and maintain acceptable catalyst performance.