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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]

Demands for improved fuel efficiency in automobiles and other vehicles have led to smaller, lighter power transmission device which result in high surface contact stress and a thin oil film, which in turn tends to cause the temperature of rolling bearings to rise. The most common temperature measurement method is to touch a thermocouple against the inner and outer rings, and this method has been used for many years. However, the method using thermocouples can only measure temperatures in a limited range near the measurement point. The authors applied the Seebeck effect, a phenomenon in which an electromotive force is generated when different metals are connected and a temperature difference is applied to bearings, to a method of measuring bearing raceway temperatures called the dynamic thermocouple method. In the dynamic thermocouple method, the average value of each contact points between the different metals generates the emf (electromotive force), so the temperature rise of all the each rolling elements in contact becomes the average value, and the exact point of temperature rise is not clear. Therefore, all but one rolling element was changed to electrically insulating zirconia balls. With this method, the contact points between many different metals became one, making it possible to identify the locations of temperature rises on the raceway surface. This method makes it possible to directly measure the temperature change of the raceway. The results of temperature measurements of the raceway surface using two types of bearings with different raceway accuracy showed a clear difference of temperature. The bearing with a poor raceway accuracy showed a temperature rise in the unloaded zone, and slippage was observed when the behavior of the rolling element was checked with a high-speed camera. Furthermore, in bearings with good raceway accuracy, the temperature of the raceway surface remained almost constant even in the non-load zone. By using the dynamic thermocouple method and observing the rolling elements with a high-speed camera, it was possible to correlate the bearing temperature rise with the behavior of the rolling elements. [ABSTRACT FROM AUTHOR]

Studies on B. terribilis cultivation have great economic and environmental relevance but are scarcely addressed in the literature. This article analyzes and compares, for the first time, the growth and metabolite productivity of B. terribilis in closed and open systems. The effect of nitrogen and phosphorus reduction on B. terribilis' main metabolites was evaluated with a 22 full factorial design, using 25, 50, and 75% of the standard concentration of these nutrients in the CHU13 medium. Proteins, carbohydrates, lipids, pigments, and hydrocarbons were extracted and quantified. It is the first time that B. terribilis hydrocarbons were extracted and characterized, using an innovative methodology validated by GC-MS. Lipids were characterized by GC-FID. The possible applications of B. terribilis oils were described. The maximum specific growth rate obtained was 0.49 day−1 with raceway cultivation. The stress condition increased lipids and hydrocarbons up to 49% and 29%, respectively, but the percentage of proteins decreased from 32 to 26%. The percentage of carbohydrates (15%) and pigments (0.41–0.86%) remained similar in the stressed and non-stressed cultivation. B. terribilis oils are suitable for biofuel synthesis, as it is composed of long-chain hydrocarbons and a higher amount of saturated and monounsaturated fatty acids. This study helps fill the gap of information about cultivation, stress, and composition of B. terribilis, supporting decision-making on the cultivation parameters and applications of this microalgae in a biorefinery context. [ABSTRACT FROM AUTHOR]

Synthetic or natural cationic polymers, such as polyacrylamide and chitosan, are exploited as coagulants due to their characteristics, such as a high positive surface charge. Due to variations in culture conditions, such as species and cell concentration, different interactions of coagulants with microalgae occur, affecting the efficiency of biomass recovery. Thus, in this study, the separation efficiency of biomass of the microalgae Scenedesmus obliquus was evaluated by coagulation-flocculation with the synthetic polymer polyacrylamide and natural polymer chitosan to optimize the dose and pH by means of a rotational central composite design. Biomass removal efficiencies greater than 90% and greater than 70% were observed for the synthetic polymer and chitosan, respectively. Notably, the reduced optical density and biological nature of microalgae make the use of response surface methodology challenging. Optimal regions with doses of 12.8 mg of synthetic polymer and 5.0 mg of chitosan were obtained per liter of microalgae sample. An optimal pH of 6.5, falling within the natural range of culture conditions was indicated for both coagulants, minimizing reagent costs. The interaction with microalgae and the potential application of chitosan and other natural coagulants that are efficient and economically viable should be explored. [ABSTRACT FROM AUTHOR]

Objective: As a type of automatic feeder, demand feeders reduce labor costs and can improve fish‐rearing efficiencies. However, mounting demand feeders can be problematic because of the variety of nonstandardized fish‐rearing units. This article describes an innovative, simple, sturdy, and durable demand feeder mount for rectangular, concrete raceways. Methods: The feeder mount was made from aluminum and sits flat on a raceway wall or walkway. A horizontal base plate, secured to the wall by vertical plates, holds a vertical riser of aluminum tubing. Attached to this tubing is a rod that secures the demand feeder. Result: This feeder mount design has proven durable over several years of actual use. Over this time, it has needed no maintenance other than occasional cleaning with water to remove spilled fish food. The feeder can be easily and quickly removed from the mount by simply pulling a pin and sliding the feeder off of the tubing. The mount is constructed to dramatically reduce tripping hazards and occupational safety and health risks. Conclusion: This simple, inexpensive (~US$50 to construct), and no‐maintenance mount is a viable solution to the typically difficult problem of mounting demand feeders to concrete raceways used for trout production. Impact statementThis article describes a relatively simple, inexpensive, no‐maintenance, and safe solution to the typically difficult problem of mounting demand feeders to concrete raceways used for fish production. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing 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.)

Demands for improved fuel efficiency in automobiles and other vehicles have led to smaller, lighter power transmission device which result in high surface contact stress and a thin oil film, which in turn tends to cause the temperature of rolling bearings to rise. The most common temperature measurement method is to touch a thermocouple against the inner and outer rings, and this method has been used for many years. However, the method using thermocouples can only measure temperatures in a limited range near the measurement point. The authors applied the Seebeck effect, a phenomenon in which an electromotive force is generated when different metals are connected and a temperature difference is applied to bearings, to a method of measuring bearing raceway temperatures called the dynamic thermocouple method. In the dynamic thermocouple method, the average value of each contact points between the different metals generates the emf (electromotive force), so the temperature rise of all the each rolling elements in contact becomes the average value, and the exact point of temperature rise is not clear. Therefore, all but one rolling element was changed to electrically insulating zirconia balls. With this method, the contact points between many different metals became one, making it possible to identify the locations of temperature rises on the raceway surface. This method makes it possible to directly measure the temperature change of the raceway. The results of temperature measurements of the raceway surface using two types of bearings with different raceway accuracy showed a clear difference of temperature. The bearing with a poor raceway accuracy showed a temperature rise in the unloaded zone, and slippage was observed when the behavior of the rolling element was checked with a high-speed camera. Furthermore, in bearings with good raceway accuracy, the temperature of the raceway surface remained almost constant even in the non-load zone. By using the dynamic thermocouple method and observing the rolling elements with a high-speed camera, it was possible to correlate the bearing temperature rise with the behavior of the rolling elements.

Currently, the steelmaking process uses a pulverized coal injection (PCI) system that serves as the heat source and reductant for ironmaking (blast furnace and FINEX) where system uses expensive high-grade coal and high operating costs. Hydrogen steelmaking is currently being developed to achieve carbon-free operation. To achieve a soft-landing during this phase of rapid change, the use of biomass and inexpensive, thermal coal, and coke dust is necessary. Research on their combustion characteristics is necessary to apply these alternative fuels to PCI. Therefore, this study analyzed the combustion characteristics of ignition delay, devolatilization, and char combustion using a laminar flow reactor visualization equipment that simulates blast furnace (BF) and FINEX PCI tuyere, using flame image data processing. The ignition time were generally longer in BF than in FINEX, and the char combustion length and time also showed the same trend due to the high oxygen rate which indicate under 2 ms on ignition delay, under 16 ms on char combustion. Also, the volatile cloud was qualitatively shown in the image to be highest in thermal coal and biomass with high volatile matter. Based on the correlation and theoretical calculation with proximate analysis and the results, ignition delay time had a combined effect of volatile matter and moisture except coke dust, and char combustion time affected unburned carbon. The combustion chemical characteristics were discussed with chemical percolation devolatilization (CPD) model parameter. Through SEM image and BET analysis, the surface area has been increased more than 10 times after combustion. Consequently, the biomass and high moisture thermal coal could cofired within 10 % and coke dust could be cofired within 9 %, respectively.

In this article, the morphology, chemical structure, alkali enrichment, and solution loss reactivity in the radial direction of the lumpy feed coke and its corresponding raceway coke from two large blast furnaces are comparatively using multiple characterization methods. The results indicate that the erosion of coke and pore development not only occurs on the surface but also in the center, which can be described as gradient reaction model. The enrichment level of K is higher than Na. K content decreases gradually from the edge to the center of the raceway coke, and the formation of nepheline causes cracks in coke observed by morphology. The crystallite order of the raceway coke is higher than that of the feed coke, with the enrichment of alkali metals, the raceway coke shows variability in the radial direction, and the orderliness gradually decreases from the surface to the interior. With the enrichment of alkali metals, the microcrystalline ordering of the raceway coke decreases from the surface to the interior, and the increase in the concentration of carbon dioxide after the entry into the raceway leads to the preferential reaction of the carbon dioxide with the coke matrix which contains K and many reactive sites. [ABSTRACT FROM AUTHOR]

As the working interface of tapered roller bearing, the raceway surface quality directly affects the working performance and service life of bearings. In order to improve the surface quality of tapered roller bearing inner raceway grinding, improve the processing efficiency, and optimize the processing parameters, this paper conducted a study on the surface roughness of the inner raceway of the outer ring of tapered roller bearings during grinding, and established a prediction model for the grinding surface roughness. Firstly, the surface topography of grinding wheel was defined by using grinding wheel parameters. Secondly, the surface roughness prediction model of bearing raceway grinding was established based on the conversion relationship between bearing raceway grinding and surface grinding and the motion trajectory of particles on grinding wheel surface. Finally, the accuracy and rationality of the model were verified by using the current industrial process parameters of grinding bearing raceway through the grinding experiments. Based on the experimental and simulation results of grinding surface roughness, the influence law of grinding wheel linear speed, workpiece speed, and grinding depth on surface roughness was explored, and the surface roughness under high grinding wheel linear speed was predicted. The research results provide a theoretical basis for optimizing surface quality of tapered roller bearing outer ring inner raceway grinding. It is found that the surface roughness decreases with the increase of grinding wheel linear speed and the decrease of workpiece speed and grinding depth. The surface roughness at high linear speed of grinding wheel is predicted. The results show that when the workpiece speed is 300 rpm and the grinding depth is 0.3 μm, the surface roughness decreases from 0.259 to 0.208 μm as the grinding wheel linear speed increases from 60 to 100 m s−1, which can provide theoretical guidance for further improving the surface quality. [ABSTRACT FROM AUTHOR]

The raceway plays a crucial role in ensuring the stable functioning of the ironmaking blast furnace. It is the key site where the chemical reaction of coke combustion takes place, providing the necessary heat and reducing gas for the upper iron ore reduction process. Consequently, the size of the raceway serves as an essential indicator of the blast furnace’s operational condition. In this study, a mathematical model for the raceway of an industrial-scale blast furnace was established. Extensive innovation investigations were conducted to explore the characteristics pertaining to the raceway’s size. The simulation outcomes demonstrate that both the particle size and the inlet velocity exert significant influences on the raceway dimensions. Specifically, the height of the raceway is predominantly affected by the particle size, whereas the inlet velocity predominantly influences the depth of the raceway.

A natural appearing microalgae-bacteria consortium was used to process urban wastewater. The process was done in an 80 m2 raceway reactor and the results were compared to an identical reactor operated using freshwater supplemented with commercial fertilisers. The biomass harvesting was done using commercial ultrafiltration membranes to reduce the volume of culture centrifuged. The membrane allowed achieving a biomass concentration of ∼9–10 g L−1. The process proposed avoids the use of centrifuges and the drying of the biomass, two of the most energy consuming steps of conventional processes. The specific growth rate in freshwater and the wastewater-based media was estimated as 0.30 ± 0.05 and 0.24 ± 0.02 days−1, respectively (p < 0.05). The maximum concentration reached at the end of the batch phase was 0.96 ± 0.03 and 0.83 ± 0.07 g L−1 when the biomass was produced using freshwater and wastewater, respectively (p < 0.05). The total nitrogen removal capacity of the system was on average 1.35 g m−2·day−1; nitrogen assimilation into biomass represented 60%–95% of this value. Furthermore, the P-PO43− removal capacity of the system varied from 0.15 to 0.68 g m−2·day−1. The outlet effluent of the reactor was used as a nutrient source in the hydroponic production of zucchini seedlings, leading to an increase in the root dry weight and the stem diameter compared to the water alone. The produced biomass showed potential for use as feedstock to produce plant biostimulants with positive effects on root development and chlorophyll retention.

The oxygen blast furnace (OBF) process with top gas recycling is recognized as a promising ironmaking process, due to its high productivity and low CO2 emissions. The solid flow plays a crucial role in this process. Therefore, the solid flow in OBF was investigated using a cold experimental OBF model in this paper. The results indicate that the plug flow is the primary solid flow pattern in the upper and middle zones of the OBF. A slight convergence flow and a smaller deadman zone were observed at the bosh. The influence of recycled gas on solid flow was found to be quite limited. Additionally, the raceway size affects the burden structure and deadman zone, but the production rate had little impact. Both the raceway size and production rate have different effects on the repose angle of the deadman zone, and it varies by 14–18°. The findings of this study may have important implications for understanding the structure of solid flow in OBF. The results can be used to optimize the process parameters and equipment design to improve the efficiency of iron production while reducing environmental impact. [ABSTRACT FROM AUTHOR]

It is critical to reveal the change in tuyere parameters for the efficient consumption of coal particles and natural gas in the lower zone of the blast furnace. Combined with the actual size and injection conditions of the blast furnace for natural gas utilization, the three-dimensional simulation model involving the tuyere, two lances, raceway and blowpipe is built to explore the influence of the tuyere diameter, tuyere length and inclination angle of tuyere on the difference of flow, temperature, gas concentration and fuel reaction in the tuyere and raceway. The research outcomes show that the change of tuyere diameter has the most significant influence on the gas velocity in the three conditions. The high-temperature district in the computational domain increases gradually with the diameter of the tuyere. However, the result is contrary to the increase of the length and inclination angle of the tuyere. Besides, when the diameter, length and inclination angle increase, the burnout of pulverized coal has a trend of decreasing, increasing and increasing, respectively. To obtain a better fuel combustion effect, it is recommended that the diameter of the tuyere should not exceed 160 mm, the length of the tuyere should not exceed 530 mm, and the inclination angle of the tuyere should not exceed 7° under the current operating conditions. • A 3D model of actual size of blast furnace injection natural gas and coal is used. • Effect of tuyere conditions on the combustion of natural gas and coal is studied. • The size of the raceway is considered after the tuyere diameter changes. • Suggestions are provided for efficient combustion of coal and natural gas. [ABSTRACT FROM AUTHOR]

In the grinding of bearing raceways, the coupling effect between grinding force and heat in the contact area between the grinding wheel and the workpiece causes changes in the material structure and mechanical properties of the raceway surface layer, which can lead to the formation of a grinding-affected layer. The grinding-affected layer has a significant impact on the service performance and fatigue life of bearings. In order to improve the ground surface quality of the outer-ring inner raceway of tapered roller bearings and optimize the processing parameters, this paper presents a study on the grinding-affected layer. A finite element simulation model for grinding the outer-ring inner raceway of the tapered roller bearing was established. The grinding temperature field was simulated to predict the affected-layer thickness during raceway grinding. The correctness of the model was verified through grinding experiments using the current industrial process parameters of bearing raceway grinding. The research results indicate that the highest grinding temperature of the outer-ring inner raceway of the tapered roller bearing is located near the center of the grinding arc area on the thin end edge. As the workpiece speed and grinding depth decrease, the highest grinding temperature decreases, and the dark layer thickness of the grinding-affected layer decreases or even does not occur. The research results can provide theoretical guidance and experimental reference for grinding the raceway of tapered roller bearings. [ABSTRACT FROM AUTHOR]

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Simple Summary: Fishmeal is a finite resource that continues to serve as the primary protein source in feeds of salmonids, including rainbow trout. Partial or total replacement of fishmeal has been successful, but many of these substitutions are of plant origin containing anti-nutritional factors that negatively impact growth and limit their dietary inclusion level. Soybean meal and processed soy have been the primary alternative protein sources utilized in rainbow trout feeds. Even at acceptable levels for normal growth, soy can cause a diarrhea-like condition that leads to poor water quality, but these impacts have not been evaluated in a commercial production setting. We showed that the use of soy protein concentrate promotes growth similar to a fishmeal diet and is superior to soybean meal under these conditions. However, soy protein concentrate led to lower water quality for some parameters and suggests that there are other considerations aside from growth when evaluating the practicality of fishmeal replacement. Juvenile rainbow trout (125 ± 0.8 g) were fed a fishmeal control diet (C), a high soy protein concentrate diet (SP), a high soybean meal diet (HiS), or a diet with high levels of fermented soy protein concentrate (fSP) for 12 weeks in a tank system capable of receiving 1st and 3rd use water from a serial-reuse production hatchery. Water quality was generally lower in 3rd use compared to 1st use water and after passing through tanks (inflow vs. outflow). Total dissolved solids were significantly higher (p = 0.003) for 3rd use compared to 1st use water, and values were also higher (p < 0.001) for the fSP diet. Turbidity and ammonia were highest in tanks for trout fed the HiS and fSP and SP and fSP diets, respectively, but were characterized by high variation, which likely prevented the detection of significant differences. Weight gain (p < 0.001) and survival (p = 0.008) were significantly lower for trout in 3rd use compared to 1st use water. Trout fed the HiS diet were generally in poorer physiological condition with lower body fat stores (p = 0.05) and lower growth rate (p < 0.001) and survival (p = 0.05) compared to the other diets, which were similar. The expression of several stress-associated genes (FK506, DIO2, REGPS, Cyp1a, G6PH, GADD45a, and IRF-1) in the liver and gill showed that diet and water source affected their regulation. Replacement of FM by SP providing 50% of dietary protein promotes acceptable growth performance compared to an FM diet and was superior to HiS. The impacts of soy protein concentrate on water quality under commercial production conditions, however, require further study. [ABSTRACT FROM AUTHOR]

Microalgae are a sustainable source for many bioproduct syntheses. This study shows how different cultivation systems and nutrient concentrations affect Chlorella sp. development. The cultivation was performed in open and closed lab-scale systems. A Tukey test was used to evaluate the significant differences between the microalgae growth and composition under the two systems analyzed. The effect of nitrogen and phosphorus concentration was analyzed with a 22 full factorial design. Lipids, carbohydrates, proteins, and pigments were extracted and quantified. The highest specific growth rate (0.52 1/day) was obtained in the open pond, with a cell density of 5.06 × 107 cells/mL and a biomass concentration of 1.30 mg/mL. In this condition, the higher concentration of pigments was obtained: 13 μg/mg of chlorophyll-a, 15 μg/mg of chlorophyll-b, and 2 μg/mg of carotenoids. An expressive increase in the lipid (from 17 to 35%) was obtained in low nitrogen and high phosphorus. Protein percentage increases with both nutrients at a higher level, reaching up to 60%. The percentage of carbohydrates decreases from 32 to 13% with phosphorus reduction. Thus, this study points out the conditions that benefit the accumulation of each Chlorella sp. metabolite, contributing to the decision-making for the cultivation and applications of this microalgae. [ABSTRACT FROM AUTHOR]

A novel raceway heat and material balance model is developed considering all physico-chemical phenomena surrounding the raceway of the blast furnace (BF). This model is unique, as it considers reactions based on thermodynamics and determines important parameters such as raceway adiabatic flame temperature (RAFT), bosh gas properties, raceway coke rate etc. Importantly, the model also predicts blowing parameters in case of known RAFT and permeability of the furnace. This paper focuses on the raceway regime only considering the effect of different injectants, H2, CO, CH4, CO2 and coke oven gas (COG). Firstly, the paper describes the modelling approach, based on thermodynamic, heat and material balances. The first part of the paper quantifies the effect of injectants on the raceway keeping the blowing parameters constant, whereas second part presents the changes of raceway properties as well as blowing parameters keeping RAFT and permeability of the furnace constant. [ABSTRACT FROM AUTHOR]

Co-injection of coal and hydrogen-rich gas with oxygen blast at tuyere is a promising technology for low carbon emission blast furnace ironmaking, which favors the development of hydrogen-based reduction and affordable carbon capture. Effects of hydrogen fraction in the co-injection gas on the combustion characteristics in raceway are numerically studied. Results show that increase of hydrogen fraction in the co-injection gas accelerates the preferential combustion of the injected gas, which promotes the preheating and pyrolysis of pulverized coal. This compensates the oxygen-grabbing effect and improves the burnout of coal from 83.2% to 86.8% with the hydrogen fraction in co-injection gas increase from 20 vol% to 80 vol%. With the CO/H 2 molar ratios in the co-injection gas of 8:2, 6:4, 4:6 and 2:8, the outlet CO/H 2 molar ratios are 54:46, 42:52, 32:68 and 24:76 respectively. Combustion, gasification and water-gas shift reactions play conjoint roles in the redistribution of reducing gas species. • EDC model is applied to consider gaseous reaction equilibrium. • The prediction accuracy of temperature fields is improved. • Increase of hydrogen fraction promotes the pulverized coal burnout. • Heat-release effect and oxygen-grabbing effect of gas preferential combustion are evaluated. [ABSTRACT FROM AUTHOR]

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[Display omitted] • The transport phenomena of full raceways in a real BF were investigated. • The effects of process parameters on coke combustion were determined. • Microstructures in coke bed under different process parameters were explored. • Correlation equations between raceway size and process parameters were established. An in-depth exploration of the kinetic behaviors of the raceway can provide practical insights for optimizing blast furnace (BF) operations. In this study, the transport phenomena and thermo-chemical behaviors in the raceway of a three-dimensional BF were simulated from particulate scale by using the discrete element method-computational fluid dynamics (DEM-CFD) approach. The effects of process parameters (blast velocity, oxygen concentration, blast temperature, coke size and distribution, tuyere insertion depth, and tuyere inclination) on coke combustion characteristics (mass fraction distributions of gas species and reaction kinetics rate) and thermo-chemical behaviors (particle volume fraction, raceway size, mass loss, and coke temperature) were investigated. Meanwhile, microstructures of coke bed were analyzed, and correlations were established for raceway size prediction. The results indicate that the mass fraction distributions of O 2 and CO are similar, both showing balloon-like shapes. The distributions of both the CO 2 mass fraction and the kinetic rates of reactions exhibit annular shapes. The raceway size increases or even overlaps with increasing blast velocity/oxygen concentration/PSD standard deviation of coke and decreasing blast temperature/coke size. Too large or too small tuyere insertion depth or tuyere inclination is not conducive to the formation of the raceway. Besides, the mass loss, temperature, and microstructures also vary with the process parameters. RSM model can well predict the raceway depth, width, and height. This study extends the particle-scale model by considering transport phenomena towards the global perspective of a real BF, and the obtained new findings on the complex reacting behaviors in the raceway will provide better insights into the optimization of the BF process. [ABSTRACT FROM AUTHOR]

• GPU-powered CFD-DEM model (GPU- rCFD-DEM) is developed to simulate the large-scale gas–solid reacting flow. • The coupling calculations between CFD and DEM are fully implemented on GPU. • Advanced coupling strategies are employed to enhance numerical stability. • Coke combustion in an industrial-scale blast furnace is simulated. The coupling of CFD (computational fluid dynamics) and DEM (discrete element method) is extensively used for simulating gas–solid reacting flows in various industrial processes, while its high computational cost limits its industry applications, especially large-scale systems with a large number of particles and complex geometries. This paper reports a robust highly efficient GPU (graphics processing unit) − powered CFD-DEM coupling approach that is, for the first time, capable of simulating large-scale gas–solid reacting flow systems with complex geometries (GPU- rCFD-DEM). The fluid flow calculations are performed using CPU parallelization, while the particle flow simulations leverage GPU parallelization, and the coupling calculations between CFD and DEM are fully implemented on GPU. The model includes advanced coupling strategies to enhance numerical stability, especially when handling complex geometries with unstructured CFD meshes. The developed model is validated through experimental measurements and its computational performance is evaluated by comparison with previous GPU-based simulations. It shows good agreement with the experiments and superior performance compared to the traditional coupling method. The model is then applied to simulate raceway dynamics and coke combustion in an industrial-scale blast furnace, showcasing its effectiveness in handling complex geometries and a huge number of particles in gas–solid reacting flows. This work provides an efficient and robust solution for numerically simulating industrial applications of gas–solid reacting flow systems. [ABSTRACT FROM AUTHOR]

The present study investigates the efficiency of raceway-based biofloc technology for the production of Penaeus vannamei and Genetically Improved Farmed tilapia in a polyculture model. Six raceway tanks were used to explore the growth performance, digestive enzyme activities, bacterial count and histology of P. vannamei reared with GIF tilapia using raceway-based biofloc and clear water raceway culture systems. Each raceway (6.8 m x 2.2 m x 3 m) was stocked with 60 shrimp/m3 of P. vannamei (0.93±0.09 g), and 5 fish/m3 of GIF tilapia (0.42±0.01 g) and reared for 90 days. Biofloc, with a carbon: nitrogen ratio of 15:1, is developed and maintained using soyahull pellet powder as organic carbon source, with continuous aeration was provided. The present study found significantly higher weight gain of P. vannamei (16.09±0.26 g) and GIF tilapia (11.71±0.35 g) in raceway-based biofloc culture system. Survival of P. vannamei and GIF tilapia did not exhibit any significant variations between raceway-based biofloc and clear water raceway systems. Significantly higher digestive enzymes activities of protease (0.25±0.01 and 0.14±0.02 U/ mg protein/min), lipase (0.88±0.04 and 0.37±0.01 U/ mg protein/min) and amylase (0.008±0.00 and 0.0016±0.00 U/ mg protein/min) are recorded in P. vannamei and GIF tilapia in raceway-based biofloc culture system, respectively. Higher values of total heterotrophic bacteria (52.25±0.88×104 CFU/ml, 49.63±1.10 ×107 CFU/g and 53.12±0.44×107 CFU/g) and bacillus counts (76.50±0.46×102 CFU/ml, 155.62±0.89×102 CFU/g and 238.75±0.82×102 CFU/g) are recorded in culture water, P.vannamei gut and GIF tilapia gut in raceway based biofloc culture system, respectively. No histopathological changes are observed in the GIF tilapia (gut), P. vannamei (gut and hepatopancreas), but deformities such as congestion of the tips of few secondary lamellae are noticed in the GIF tilapia (gill) reared in the clear water raceway system. Therefore, the study suggests that polyculture of P. vannamei and GIF tilapia in a raceway-based biofloc system is advantageous over the clear water raceway system in terms of production augmentation with improved physiological conditions. • Raceway based technology improves growth performance of Penaeus vannamei and GIF tilapia under polyculture conditions • BFT based polyculture studies enabled a better control on water quality and optimal growth of heterotrophic bacteria. • A hybrid system of raceway based BFT with polyculture suggested as sustainable and environmental beneficial technology. [ABSTRACT FROM AUTHOR]

The oxygen blast furnace (OBF) process with top gas recycling is recognized as a promising ironmaking process, due to its high productivity and low CO2 emissions. The solid flow plays a crucial role in this process. Therefore, the solid flow in OBF was investigated using a cold experimental OBF model in this paper. The results indicate that the plug flow is the primary solid flow pattern in the upper and middle zones of the OBF. A slight convergence flow and a smaller deadman zone were observed at the bosh. The influence of recycled gas on solid flow was found to be quite limited. Additionally, the raceway size affects the burden structure and deadman zone, but the production rate had little impact. Both the raceway size and production rate have different effects on the repose angle of the deadman zone, and it varies by 14–18°. The findings of this study may have important implications for understanding the structure of solid flow in OBF. The results can be used to optimize the process parameters and equipment design to improve the efficiency of iron production while reducing environmental impact.

Este trabajo presenta una primera aproximación al control robusto del pH en un fotobiorreactor raceway para el cultivo de microalgas. En este tipo de procesos el pH es la variable más crítica a controlar teniendo una relación directa con la productividad del sistema. La dinámica del pH posee un carácter fuertemente no lineal estando afectada por numerosos factores tales como el aporte del CO2 al medio de cultivo o la realización de la fotosíntesis por parte de las microalgas. Esta no linealidad genera una gran fuente de incertidumbre en el proceso incluso cuando el sistema es controlado alrededor del punto de operación deseado. Por tanto, en este artículo se ha procedido a realizar el modelado del sistema con incertidumbre paramétrica cubriendo los rangos de trabajo típicos del pH, y posteriormente se ha realizado el diseño de un controlador robusto con la técnica Quantitative Feedback Theory (QFT) para conseguir unos requisitos de rendimiento y estabilidad robustos determinados. El algoritmo de control resultante se ha evaluado en simulación y mediante ensayos reales frente a distintas condiciones de trabajo y en distintos puntos de operación, obteniéndose resultados satisfactorios.

Copyright of Bearing is the property of Bearing 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.)

Copyright of Bearing is the property of Bearing 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.)

The composition and microstructure of charging coke and raceway coke (R-coke) of a blast furnace were studied by various detection methods. The gasification reactivity and reaction activation energy of the two samples were compared by thermogravimetric method under non isothermal and isothermal conditions. The results show that the R-coke level spacing d002 is slightly smaller than that of the coke, and the graphite layer accumulation height Lc and graphite layer size are significantly higher than that of the coke. The coke undergoes chemical erosion and physical wear in the blast furnace with microscopic pore development and increased surface structural irregularity. The high overlap of alkali metal K and Na with Si and Al elemental distribution positions on the surface of R-coke indicates the generation of complex compounds. In the non-isothermal gasification process, the rate-controlling of the gasification process gradually shifts from chemical reaction to diffusion as the conversion of the sample increases. Diffusion becomes the only limiting link of the reaction during isothermal gasification, and the pore structure is the main factor affecting the gasification rate. Since the pore structure of R-coke is more developed than that of coke, the activation energy of the reaction is lower, which is conducive to the diffusion of CO2 molecules to the reaction interface and the diffusion of the product CO to distant places, thus making the reaction rate of R-coke higher than that of coke. [ABSTRACT FROM AUTHOR]

Pig farming generates highly polluted wastewater that requires effective treatment to minimize environmental damage. Microalgae can recover nutrients from piggery wastewater (PWW), but excessive nutrient and turbidity levels inhibit their growth. Solar photo-Fenton (PF) offer a sustainable and cost-effective pretreatment to allow microalgal growth for further PWW treatment. This study optimized the concentrations of PF reagents to minimise water and nutrient inputs while maintaining microalgae-based treatment efficiency. PF trials were conducted in pilot-scale raceway ponds under solar radiation, testing different concentrations of FeSO 4 (4.48 and 8.95 mM) and H 2 O 2 (77, 154, and 309 mM). Following PF, Tetradesmus obliquus was used in a biological treatment of PWW to recover the remaining nutrients. PF achieved high removal efficiencies for turbidity (97.6-99.5 %), total organic carbon (59.2-77.1 %), and chemical oxygen demand (83.8-94.7 %), but ammonium was not significantly removed. Phosphorus was almost completely removed through iron precipitation during neutralisation. Lowering the H 2 O 2 concentration from 309 to 77 mM did not compromise removal efficiency but reducing FeSO 4 below 8.95 mM negatively affected the process. Consequently, 8.95 mM FeSO 4 and 77 mM H 2 O 2 were selected for microalgae production. The pretreated PWW could be recycled at least once for microalgal production, without nutrient supplementation, improving biomass productivity and PWW treatment, especially targeting ammonium. Phosphorus supplementation, however, did not significantly boost biomass productivity or treatment efficiency. Moreover, the iron sludge generated from PF pretreatment contained enough NPK to be repurposed as an organic fertilizer boosting sustainable agricultural practices. These findings encourage further investigation of this emerging combined technology towards wastewater treatment at large-scale., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Juvenile rainbow trout (125 ± 0.8 g) were fed a fishmeal control diet (C), a high soy protein concentrate diet (SP), a high soybean meal diet (HiS), or a diet with high levels of fermented soy protein concentrate (fSP) for 12 weeks in a tank system capable of receiving 1st and 3rd use water from a serial-reuse production hatchery. Water quality was generally lower in 3rd use compared to 1st use water and after passing through tanks (inflow vs. outflow). Total dissolved solids were significantly higher (p = 0.003) for 3rd use compared to 1st use water, and values were also higher (p < 0.001) for the fSP diet. Turbidity and ammonia were highest in tanks for trout fed the HiS and fSP and SP and fSP diets, respectively, but were characterized by high variation, which likely prevented the detection of significant differences. Weight gain (p < 0.001) and survival (p = 0.008) were significantly lower for trout in 3rd use compared to 1st use water. Trout fed the HiS diet were generally in poorer physiological condition with lower body fat stores (p = 0.05) and lower growth rate (p < 0.001) and survival (p = 0.05) compared to the other diets, which were similar. The expression of several stress-associated genes (FK506, DIO2, REGPS, Cyp1a, G6PH, GADD45a, and IRF-1) in the liver and gill showed that diet and water source affected their regulation. Replacement of FM by SP providing 50% of dietary protein promotes acceptable growth performance compared to an FM diet and was superior to HiS. The impacts of soy protein concentrate on water quality under commercial production conditions, however, require further study.

Despite measures to increase pulverised coal (PC) conversion, part of the injected PC leaves the raceway as char, particularly at high injection rates. The coke/PC replacement ratio and, consequently, the blast furnace (BF) operation efficiency depends on the consumption of char by reactions of secondary gasification and added burden. This contribution focuses on the change in streaming conditions in different BF zones when coal particles leave the raceway. To investigate this, a 2-D physical BF cold model was used. Tests were conducted after injecting various amounts of PC and under various gas flow rates. Particle movement and accumulation were examined by measuring the pressure drop at different positions in the model. To evaluate the effect of PC on the gas permeability in vertical and horizontal directions, calculations using the Darcy-Weisbach/Ergun equation were performed. The results will be used to improve CFD-modelling and the prediction of char behaviour in the BF. [ABSTRACT FROM AUTHOR]

Raceway reactors are still the most extensive technology for microalgae production. However, these reactors have some drawbacks, one of them being a low mass transfer capacity, which provokes dissolved oxygen accumulation and thus reduction of system performance. To overcome this problem, it is imperative to improve the photobioreactor design as well as the operating conditions. One solution is to maintain the dissolved oxygen below defined limits. In this work, a new control algorithm is proposed to improve the mass transfer capacity of raceway reactors while at the same time reducing air injection costs. The main idea of the proposed control approach is that only the necessary amount of airflow will be applied according to transfer capacity demand. This control strategy was first analyzed in simulation and compared with classical On/Off solutions, and subsequently evaluated in outdoor conditions in a photobioreactor of 80 m2. • Dissolved oxygen control in raceway reactors based on mass transfer demand. • Improvement of mass transfer capacity and reduction of production costs. • Experimental tests demonstrate the capabilities of the proposed methodology. [ABSTRACT FROM AUTHOR]

This paper presents a tool to simulate the biomass production capacity of microalgae-based processes as a function of the prevailing weather conditions at selected locations around the world. The tool is designed for the use of raceway reactors operated in turbidostat mode, allowing for the simulation of biomass production at whatever location for different strains as a function of reactor size, culture depth, and biomass concentration in the reactor. The tool integrates the solar radiation and temperature data available in existing databases for the selected location to determine the light availability and temperature impact in the culture, to finally provide the growth rate and biomass productivity. Hourly values are calculated to estimate a detailed overview of cultures performance, and finally, mean daily and annual values are calculated. The simulation tool developed is a very useful instrument for decision-making processes about the installation of microalgae-related facilities, and also allows the determination of the potential production capacity. [Display omitted] • Simulation of microalgae production around the world • Comparison of microalgae genus production in different locations • A graphical tool to estimate microalgae production in raceway reactors • Evaluation of reactor size, culture depth, and biomass concentration effects [ABSTRACT FROM AUTHOR]

Silicon [Si] in hot metal is an impurity acting in the steel shop as an energy source that is released by oxidation during oxygen blowing in the converter. Preferred silicon concentration in hot steel is typically 0.4 wt-% (± 0.1 wt-%), helping predictable and low-cost processing. In practice, the Si concentration is difficult to control and may occasionally reach levels higher than 1 wt-%. The authors studied data from observations, samples and autopsies of a chilled blast furnace, a core drill and a furnace in operation. In addition, production data from a melting reduction pilot plant (HIsarna) and FactSage® calculations were used. The amount of FeO in the raceway, the area in which hot gas and powdered coal (PCI) are introduced in the blast furnace, in relation to [Si] in hot metal, is observed. The goal of this paper is to contribute to a better understanding about the mechanism of the dissolution of silicon in hot metal. [ABSTRACT FROM AUTHOR]

Context: Increasingly, ecological studies of sea turtles are measuring locomotion performance of newly emerged hatchlings in raceways and swimways under the assumption that locomotion performance measured in these structures reflects locomotion performance in nature, and that such measurements reflect the chance of a hatchling surviving dispersion from their natal beach. Aims: The aim was to test the assumption that an individual hatchling's performance measured in artificial structures is correlated with the same individual's performance in the natural environment (beach and sea), adding confidence that such measurements are an indirect indicator of dispersal ability during the first 24 h of post-nest life. Methods: Green turtle (Chelonia mydas) hatchlings that had just emerged from their nest had their crawling and swimming speeds measured in an on-beach raceway and swimway. The same hatchlings then had their beach crawling and sea swimming speed measured and the correlation between their performance in the artificial structures and natural crawls and swims calculated. Key results: An individual sea turtle hatchling's locomotion performance in nature was correlated with its locomotion performance in raceways and swimways, but beach crawling was generally slower than raceway crawling, and sea swimming was generally faster than swimway swimming. We also found a weaker correlation between the raceway and beach crawling speeds than the sea and swimway swimming speeds. Conclusions: The measurement of sea turtle hatchling crawling speed and swimming speed in artificial structures correlated with the individual's locomotion performance in nature, supporting the assumption that the locomotion performance measured in artificial structures reflects their relative locomotion performance in the natural environment. Implications: The measurement of sea turtle hatchlings locomotion performance in artificial structures can be used to indicate how variations in the nest microenvironment such as temperature and moisture affect a hatchling's real-life locomotion performance, and thus reflect a hatchling's dispersal ability during the first 24 h of post-nest life. Thus, sea turtle rookery managers can use this information to assess how their incubation management strategies affect hatchling locomotion performance, and consequently their likely offshore dispersal ability. While moving from their nest to the open ocean, sea turtle hatchling dispersal is dependent on their locomotion performance. Locomotion performance can be measured in simple artificial structures, and we found that crawling and swimming in these structures is correlated with crawling on the beach and swimming in the sea. Thus, measurement of locomotion performance in artificial structures can be used to indicate relative dispersal ability of sea turtle hatchlings during their beach crawl and initial phase of the swimming frenzy. Photograph by David Booth. [ABSTRACT FROM AUTHOR]

We present a modified model of algae growth in a raceway pond with the additional feature of variable pond depth. This requires an additional state variable to model depth as well as additional control to allow for variable outflow. We apply numerical optimal control methods to this model and show that the lipid yield of the process can be increased by 67% compared to that obtained with a fixed pond depth. [ABSTRACT FROM AUTHOR]

The scaling of Raceway bioreactors was studied by geometric and mechanical similarity, with an order of magnitude of 1:10. The hydrodynamic parameters involved (flow velocity, hydrodynamic stress or shear stress, dimensionless numbers of Re, Fr, and Euler Power) at different stirring speeds (30, 35, 40, and 45 rpm) were determined. The study, carried out using low-density particle imaging velocimetry (PIV), showed that the speed of the liquid medium remains above 30 cm/s from 30 rpm, which ensures turbulence in the system. The flow velocity suffers a decrease of approximately 18%, at different angular velocities, with similar biomass concentrations (3.24 × 105–3.72 × 105 cells/mL). This decrease in speed directly affects the values of all the parameters involved in the bioreactor. Furthermore, the measurement of hydrodynamic stress (τ) indicates that the microorganisms are exposed to a value of 0.299 Pa at 35 rpm and 0.370 Pa at 40 rpm. Due to mechanical agitation, hydrodynamic stress values in Raceway systems have not been previously reported. The studies were carried out in a 10 L Raceway bioreactor using a consortium of microalgae and cyanobacteria where Spirulina sp. and Pseudanabaena sp. predominate. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing 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.)

Raceway is a key region in ironmaking blast furnace (BF). While the raceway depth is extremely difficult to measure, thermal images near tuyeres may be available. In this study, inspired by the concept of digital-twin, a soft-sensor approach is proposed to estimate the raceway depth from thermal images. This approach includes (1) The representative thermal images are generated through a raceway CFD model under industry-scale conditions of a specific BF; (2) A principal component analysis (PCA) method is used to reduce data dimension and extract key features from the thermal images of high dimension; (3) A model-learning tool, support vector machine (SVM) is developed to learn the underlying data-driven soft-sensor model between extracted features from PCA and raceway depth from CFD simulations. The result shows that the soft-sensor model can effectively capture the latent relationship between thermal images and the raceway depth, which can be used to estimate raceway depth in real-time in practice. [Display omitted] • A soft-sensor approach is proposed to estimate raceway depth from thermal images. • Representative thermal images and corresponding raceway depths are generated by CFD simulations. • Important features from high-dimensional thermal images are extracted. • The soft-sensor predictions are comparable with CFD results. • Raceway depths can be estimated in real-time using developed soft-sensor model. [ABSTRACT FROM AUTHOR]

[Display omitted] • The raceway behaviours of a slow-moving packed bed solid fuel gasifier are studied mathematically. • The model considers multi-fluid flow, coupled with heat transfer and heterogenous reactions inside and around all the raceways of such a gasifier. • Probability theory and statistics are used to quantitatively analyse the raceway results. The moving-bed gasifier of solid fuels (e.g., coal or biomass) is a key chemical reactor to convert coal or biomass to clean fuel, where the profile of the raceway cavity and its flow-thermal-chemical behaviours can affect the performance of the gasifier, however, they are not well understood because of the process complexity and modelling challenge. In this study, an advanced 3D multi-fluid model, based on the Eulerian-Eulerian method, coupled with heat transfer and heterogenous reactions, is developed to describe the reacting flow behaviours inside and around the raceways. It is found that raceways inside the slow-moving packed bed gasifier are of balloon-like shapes; they are built in just a few seconds after issuing the jet from gas entry, and then both the average velocity for gas and particle are relatively stable. The gauge pressure conditions are not isobaric, and high temperatures, small gas densities and high reaction rates are observed near the raceway "shell". Besides, it is found the raceway behaviours on horizontal cross-section feature more symmetry compared to those on other directions. In addition, probability theory and statistics are used to analyse the quantitative raceway results, and possibilities related to the distributions of gas properties, momentum and species are discussed. This model provides an effective tool to systematically study and optimise raceway behaviours inside a slow-moving packed bed solid fuel gasifier. [ABSTRACT FROM AUTHOR]