Search Results (18)

Biomass oxy-fuel combustion based on circulating fluidized bed (CFB) technology is one of the important pathways to achieving carbon neutrality due to its potential in carbon capture and negative carbon emissions. Combining biomass, as a substitute for coal, with oxy-fuel combustion technology can enrich CO₂ while helping to control NOx emissions and carbon stock. In this study, a three-dimensional numerical model of a 20 t/h biomass CFB boiler was established based on the computational particle fluid dynamics (CPFD) method. Under an oxy-fuel atmosphere of 30% O₂/65% CO₂/5% H₂O, the combustion characteristics of three typical biomass fuels—corn straw, rice husk, and poplar wood—were systematically compared, with emphasis on the furnace temperature distribution and the formation and emission of CO, NO_X, and SO₂. The results show that the axial temperature profiles all exhibit a rapid increase to a peak, followed by a gradual decrease. The peak temperatures in descending order are poplar wood (1091 K), corn straw (1084 K), and rice husk (1047 K), and the differences are mainly attributed to variations in volatile content, ash content, and calorific value. CO is primarily concentrated in the dense phase zone; it increases first and then decreases along the furnace height. CO generated from poplar wood combustion has the highest concentration at the furnace outlet, while the steady-state outlet mass fraction of NO is the lowest for poplar wood. Corn straw combustion yields the highest NO emission. Overall, the carbon stock of the three fuels is very low, and total CO emission is extremely low. NO concentration is jointly regulated by fuel nitrogen content and CO reduction, while SO₂ emission is directly related to fuel sulfur content—corn straw and rice husk show significantly higher SO₂ emission than poplar wood due to their higher sulfur content. In summary, fuel characteristics play a decisive role in the temperature field and pollutant formation during oxy-fuel combustion. This study provides a theoretical basis for the fuel selection and operational optimization of biomass oxy-fuel CFB boilers. Full article

Oxy-fuel combustion technology is a critical pathway for carbon capture in the cement industry. However, the high-concentration CO₂ atmosphere significantly alters multiphysics coupling in the calciner and systematic studies on its comprehensive effects remain limited. To address this, a Computational Particle Fluid Dynamics (CPFD) model using the MP-PIC method was implemented using the commercial software Barracuda Virtual Reactor 22.1.2 to simulate an industrial-scale oxy-fuel cement calciner and validated against industrial data. Under oxy-fuel combustion with 50% oxygen concentration in the tertiary air, simulations showed a 38.4% increase in the solid–gas mass ratio compared to conventional air combustion, resulting in a corresponding 37.7% increase in total pressure drop. Flow resistance was concentrated primarily in the constriction structures. Local temperatures exceeded 1200 °C in high-oxygen regions. The study reveals a competition between the inhibitory effect of high CO₂ partial pressure on limestone decomposition and the promoting effect of elevated overall temperature. Although the CO₂-rich atmosphere thermodynamically suppresses calcination, the higher operating temperature under oxy-fuel combustion effectively compensates, achieving a raw meal decomposition rate of 92.7%, which meets kiln feed requirements. This research elucidates the complex coupling mechanisms among flow, temperature, and reactions in a full-scale oxy-fuel calciner, providing valuable insights for technology design and optimization. Full article

Particle separation is a common process in various industries, particularly in mineral processing. Therefore, this research aimed to evaluate the performance of separation method using fluidized bed. The evaluation was performed using silica gel particle with diameters of 0.9 and 3 mm, including diesel fuel as fuel. This simulation was carried out to obtain the optimum separation of small-sized particle (0.9 mm) based on variations in fluid velocity (0.034, 0.068, and 0.102 m/s), outlet height (0.3, 0.6, and 0.9 m), and time. Optimum separation, defined by maximum separation efficiency (99%) in minimum time for separation, was determined using Computational Particle Fluid Dynamics software (CPFD VR 17.4.0). Separation efficiency of simulation results was validated by experimental research The results showed that, at velocity of 0.034 m/s, big particle could be partially separated at an outlet height of 0.9 m. At velocity of 0.068 m/s, small particle was separated at an outlet height of 0.6 m for 220 s, and big particle at 0.9, with a time longer than 300 s. Based on these results, optimum condition was obtained at velocity of 0.102 m/s, where small and big particle was separated at a time of 100 s, with output heights of 0.9 and 0.6 m, respectively. Full article

Purpose: Urinary incontinence (UI) significantly impacts the quality of life, necessitating a range of treatments, from behavioral changes to surgical interventions. Electromagnetic muscle stimulation (HIFEM™) therapy presents an innovative, non-invasive approach to strengthening pelvic floor muscles (PFMs). Subjects and Methods: This retrospective, non-interventional case series study explores the efficacy and safety of HIFEM™ treatment in parous women experiencing stress (SUI) and mixed urinary incontinence (MUI). Nineteen women (mean age 54 ± 16) underwent six HIFEM™ sessions, with symptom progression tracked using the International Consultation on Incontinence Questionnaire-Urinary Incontinence Short Form (ICIQ-UI SF), along with comfort and satisfaction questionnaires. Results: At baseline, the mean ICIQ-UI SF score was 7.9 ± 4.2 points. By the final questionnaire administration, the average score had dropped to 4.7 ± 3.5, reflecting a 50.6% reduction from baseline (p < 0.001). According to ICIQ-UI SF Item 6, 21% of subjects achieved complete continence. Additionally, the percentage of subjects experiencing urine leakage before reaching the toilet declined by 40% after the sixth treatment. Post treatment, the number of subjects who leaked urine while coughing or sneezing decreased by 50%. Conclusions: The treatment has shown high efficacy in lowering the ICIQ-SF scores across the study group, with a significant number of subjects regaining entire continence. Full article

This critical review evaluates chemical looping combustion using a syngas derived from gasified biomass (BMD Syngas). It is anticipated that establishing such a process will open new opportunities for CO₂ sequestration and the use of highly concentrated CO₂ in the manufacturing and synthesis of fuels from entirely renewable feedstocks. This review focuses on the process conducted through using two interconnected fluidized bed units: a nickel oxide reduction unit (an endothermic Fuel Reactor) and a nickel oxidation unit (an exothermic Air Reactor). In this respect, a high-performance OC (HPOC) with Ni on a γ-Al₂O₃ fluidizable support (20wt% Ni, 1wt% Co, 5wt% La/γ-Al₂O₃) was developed at the CREC (Chemical Reactor Engineering Centre) of the University of Western Ontario, Canada. The HPOC was studied in a CREC Riser Simulator. The benefits of this mini-fluidized unit are that it can be operated at 2–40 s reaction times, 550–650 °C temperatures, 1.3–2.5 H₂/CO ratios, and 0.5–1 biomass/syngas stoichiometric ratios, mimicking the conditions of industrial-scale CLC units. When using a syngas derived from biomass and the HPOC under these operating conditions, 90% CO, 92% H₂, and 88% CH4 conversions, together with a 91% CO₂ yield, were obtained. These results allowed the prediction of a 1.84–3.0 wt% ($g_{O_2}/g_{{OC}_{}}$) oxygen transport capacity, with a 40–70% nickel oxide conversion. The experimental data acquired with the CREC Riser Simulator permitted the development of realistic kinetic models. The resulting kinetics were used in combination with Computational Particle Fluid Dynamics (CPFD) to demonstrate the operability of a large-scale industrial syngas CLC process in a downer fuel unit. In addition, these CPFD simulations were employed to corroborate that high CO₂ yields are achievable in 12–15 m length downer fuel units. Full article

Increasingly globally prevalent obesity and related metabolic disorders have underscored the demand for safe and natural therapeutic approaches, given the limitations of weight loss drugs and surgeries. This study compared the phytochemical composition and antioxidant activity of five different varieties of citrus physiological premature fruit drop (CPFD). Untargeted metabolomics was employed to identify variations in metabolites among different CPFDs, and their antilipidemic effects in vitro were assessed. The results showed that Citrus aurantium L. ‘Daidai’ physiological premature fruit drop (DDPD) and Citrus aurantium ‘Changshan-huyou’ physiological premature fruit drop (HYPD) exhibited higher levels of phytochemicals and stronger antioxidant activity. There were 97 differential metabolites identified in DDPD and HYPD, including phenylpropanoids, flavonoids, alkaloids, organic acids, terpenes, and lipids. Additionally, DDPD and HYPD demonstrated potential antilipidemic effects against oleic acid (OA)-induced steatosis in HepG2 hepatocytes and 3T3-L1 adipocytes. In conclusion, our findings reveal the outstanding antioxidant activity and antilipidemic effects of CPFD, indicating its potential use as a natural antioxidant and health supplement and promoting the high-value utilization of this resource. Full article

In this study, the co-combustion of coal and biomass, and the tri-combustion of coal, biomass, and oil sludge in a 130 t h⁻¹ circulating fluidized bed (CFB) boiler are investigated via the computational particle fluid dynamics (CPFD) approach. Furthermore, the effect of biomass feeding position is also comprehensively evaluated. The results show that for the co-combustion of coal and biomass, the O₂ mole fraction at the furnace outlet rises from 0.0541 to 0.0640 as the biomass blending ratio enhances from 40% to 100%, while the CO₂ mole fraction reduces from 0.1357 to 0.1267. The mole fraction of NO_x and SO₂ at the furnace outlet decreases from 4.5867 × 10⁻⁵ to 3.9096 × 10⁻⁵ and 2.8253 × 10⁻⁴ to 4.6635 × 10⁻⁵, respectively. For the tri-combustion of three fuels, the average NO_x mole fraction initially grows quickly and then declines gradually, ranging from 4.1173 × 10⁻⁵ to 4.2556 × 10⁻⁵. The mole fraction of SO₂ at the furnace outlet increases from 3.5176 × 10⁻⁴ to 4.7043 × 10⁻⁴ when the ratio of oil sludge rises from 10% to 20%. The uniformity of temperature and gas components distribution is “new inlet > secondary air inlet > feed inlet”. As for the three inlet positions, the mole fractions of NO_x at the furnace outlet are between 3.9096 × 10⁻⁵ and 5.1537 × 10⁻⁵, while those for SO₂ are between 2.5978 × 10⁻⁴ and 2.5278 × 10⁻⁴. Full article

This study reports a novel hybrid model for the prediction of six critical process variables of importance in an industrial-scale FCC (fluid catalytic cracking) riser reactor: vacuum gas oil (VGO) conversion, outlet riser temperature, light cycle oil (LCO), gasoline, light gases, and coke yields. The proposed model is developed via the integration of a computational particle-fluid dynamics (CPFD) methodology with artificial intelligence (AI). The adopted methodology solves the first principle model (FPM) equations numerically using the CPFD Barracuda Virtual Reactor 22.0^® software. Based on 216 of these CPFD simulations, the performance of an industrial-scale FCC riser reactor unit was assessed using VGO catalytic cracking kinetics developed at CREC-UWO. The dataset obtained with CPFD is employed for the training and testing of a machine learning (ML) algorithm. This algorithm is based on a multiple output feedforward neural network (FNN) selected to allow one to establish correlations between the riser reactor feeding conditions and its outcoming parameters, with a 0.83 averaged regression coefficient and an overall RMSE of 1.93 being obtained. This research underscores the value of integrating CPFD simulations with ML to optimize industrial processes and enhance their predictive accuracy, offering significant advancements in FCC riser reactor unit operations. Full article

Astaxanthin is a xanthophyll carotenoid possessing impressive nutraceutical, antioxidant, and bioactive merits. Traditionally, astaxanthin is extracted from crustacean wastes via solvent extraction methods. However, the rigid structure of shells that comprise complex proteins and chitin challenges the extraction process. This investigation addressed an efficient microbial-assisted method to facilitate astaxanthin recovery from crab exoskeleton waste utilizing chitinolytic and proteolytic microorganisms. Herein, we evaluated the effect of pretreatment of the exoskeleton waste with a newly isolated probiotic strain, Bacillus amyloliquefaciens CPFD8, showing remarkable protease and chitinase activity and a proteolytic Saccharomyces cerevisiae 006-001 before solvent extraction, using acetone/hexane, on astaxanthin recovery. Furthermore, the antioxidant and anti-inflammatory activities of the recovered astaxanthin were inspected. Results revealed that both strains boosted the astaxanthin yield from the crab (Callinectes sapidus) exoskeleton compared with solvent extraction using acetone/hexane. Under optimum conditions, astaxanthin yield was 217 and 91 µg/g crab exoskeleton in samples treated with B. amyloliquefaciens CPFD8 and S. cerevisiae 006-001, respectively. Interestingly, pretreatment of crab exoskeleton waste with B. amyloliquefaciens CPFD8 yielded more than 6-fold astaxanthin compared with the solvent extraction method that yielded just 35 µg/g. This increase could be attributed to the proteolytic activity of B. amyloliquefaciens CPFD8 that rendered deproteinized shell chitin accessible to chitinase, facilitating the penetration of solvents and the recovery of astaxanthin. The recovered astaxanthin exhibited excellent antioxidant activity in scavenging DPPH or ABTS free radicals with IC₅₀ values of 50.93 and 17.56 µg/mL, respectively. In addition, the recovered astaxanthin showed a remarkable anti-inflammatory impact on LPS-induced murine macrophage RAW264.7 cells and significantly inhibited the production of nitric oxide, TNF-α, and IL-6 compared with the untreated control. These findings suggest the potential use of the developed microbial-assisted method utilizing chitinolytic and proteolytic B. amyloliquefaciens CPFD8 to maximize the recovery of bioactive astaxanthin from crab (C. sapidus) exoskeleton waste. Full article

Biomass fuels play an important role in the field of fluidized bed combustion, but due to the diversity and uncertainty of fuels, there are usually some problems of high CO emission that cannot be directly solved by combustion adjustment. In this paper, a 75 t/h biomass fluidized bed was taken as the research object. It was observed from the field test that the gas incomplete combustion loss reached 12.13% when mono-combustion of wheat straw was conducted, and the CO concentration in the exhaust gas exceeded 30k ppm. Combined with the CPFD numerical simulation, the combustion characteristics and influence of secondary air layout on CO reduction performance were discussed in detail. The results revealed that the gas temperature gradually increased along furnace height under the initial condition, and the maximum temperature was more than 1000 °C at furnace outlet. The air curtain of the secondary air jets was insufficient, and the wheat straw rose rapidly as it entered into the furnace. By arranging adjacent secondary air ports above each fuel-feeding inlet, the residence time of particles in the furnace could be significantly increased, thus, the furnace temperature distribution was more reasonable and the CO emission was reduced by 58.6%. Full article

The efficiency of a fluidized bed reactor depends on the bed fluid dynamic behavior, which is significantly influenced by the bubble properties. This work investigates the bubble properties of a bubbling fluidized bed reactor using computational particle fluid dynamic (CPFD) simulations and electrical capacitance tomography (ECT) measurements. The two-dimensional images (along the reactor horizontal and vertical planes) of the fluidized bed are obtained from the CPFD simulations at different operating conditions. The CPFD model was developed in a commercial CPFD software Barracuda Virtual Reactor 20.0.1. The bubble behavior and bed fluidization behavior are characterized form the bubble properties: average bubble diameter, bubble rise velocity, and bubble frequency. The bubble properties were determined by processing the extracted images with script developed in MATLAB. The CPFD simulation results are compared with experimental data (obtained from the ECT sensors) and correlations in the literature. The results from the CPFD model and experimental measurement depicted that the average bubble diameter increased with an increase in superficial gas velocities up to $4.2 U_{mf}$ and decreased with a further increase in gas velocities due to the onset of large bubbles (potential slugging regime). The bubble rise velocity increased as it moved from the lower region to the bed surface. The Fourier transform of the transient solid volume fraction illustrated that multiple bubbles pass the plane with varying amplitude and frequency in the range of 1–6 Hz. Further, the bubble frequency increased with an increase in superficial gas velocity up to $2.5U_{mf}$ and decreased with a further increase in gas velocity. The CPFD model and method employed in this work can be useful for studying the influence of bubble properties on conversion efficiency of a gasification reactor operating at high temperatures. Full article

In this work, the computational particle fluid dynamics (CPFD) method is used to simulate the high-pressure visual fluidized bed experimental equipment independently designed and developed by the experimentation of the fluidized reduction process of iron ore powder. A numerical model for reducing iron ore fines in a three-dimensional fluidized bed is established, and the model is verified by combining numerical simulation and experimental testing. Moreover, the influences of different reducing factors on the reduction effect in the process of the fluidized reduction of iron ore fines are simulated in detail. Via the CPFD simulation of the fluidized reduction of iron ore fines, the optimal reduction pressure is found to be 0.2 MPa, and the optimal reducing gas is found to be H₂. Moreover, the optimal gas velocity is 0.6 m/s, and the optimal reduction temperature is 923 K. This conclusion is consistent with the experimental measurements, so the simulation results can be used to verify the reliability of the optimal operating conditions. Full article

A cold-flow lab-scale cross-flow fluidized bed classifier was simulated using the CFD software Barracuda VR^®. The purpose of the study was to identify the most suitable drag model and make the model adjustments that provide the best representation of the flow situation in the classifier when comparing the results with the experimental data. Two particle types were used in the simulations and in the experiments: zirconia (median diameter 69 µm, skeletal density 3830 kg/m³) and steel (290 µm, 7790 kg/m³). Ten different cases, with different solids loading values, were investigated: three with pure zirconia particles, three with pure steel particles, and four with a mixture of zirconia (28%) and steel (72%). Several different drag models were tried out in the simulations. However, none of the available models were able to predict the classification efficiency observed in experiments with their default settings. Although most of the drag models correctly predicted the inversely proportional behavior of the classification efficiency vs. solids loading, the classification efficiency was overpredicted. It was observed that a combined WenYu/Ergun drag model gave a wide range of accuracy, by being able to capture the behavior of both dense and dilute particle systems. Even though the predictions of the classification efficiency for steel particles were acceptable, a larger deviation was observed with Geldart A zirconia particles. CFD simulations with the WenYu and Ergun combined drag model were used for further validation against the experimental observations. In this case, previously published experimental data for fluidization of pure Zirconia particles were used. The fluidization of zirconia was modelled in Barracuda VR^® with adjustment of the combined WenYu/Ergun drag model parameter (k₁), to obtain a suitable validation. Furthermore, the effect of adding the blended acceleration model (BAM) for the fluidization simulations is discussed. It was observed that the fixed bed pressure drop was very accurate compared to the experimental observation, but the pressure drop after the fluidization was slightly overpredicted. Full article

Airflow classification is the key technology for the dry separation of manufactured sand. To solve the problem of low separation accuracy and poor gradation grade, the classification process of manufactured sand under different inlet and outlet airflow velocities changes in the multi-air inlet classifier is simulated by using Barracuda based on Computational Particle Fluid Dynamics (CPFD) method. The influence of various airflow velocity in air inlets and outlet on the sand classification is analyzed. The optimal combination of airflow velocity that meets the design goals is obtained. The results show that the airflow velocity and location of the air inlet and outlet have a significant impact on medium-grained (0.15~1.18 mm) and fine-grained (0.075~0.3 mm) sand. Adjusting the airflow velocity at air inlet 2 and air outlet can most effectively change the overall sand separation effect, while 41 m/s (inlet 2) and 6 m/s (outlet) would be the best velocity combination. Full article

The leaves of Carica papaya (CP) are rich in natural antioxidants. Carica papaya has traditionally been used to treat various ailments, including skin diseases. This study aims to decipher the antioxidant effects and phytochemical content of different CP leaf extracts (CPEs) obtained using supercritical carbon dioxide (scCO₂) and conventional extraction methods. The antioxidant activities of CPEs were evaluated by cell-free (1,1-diphenyl-2-picryl-hydrazyl (DPPH) and ferric-reduced antioxidative power (FRAP)) and cell-based (H₂O₂) assay. Both C. papaya leaf scCO₂ extract with 5% ethanol (CPSCE) and C. papaya leaf scCO₂ extract (CPSC) exhibited stronger DPPH radical scavenging activity than conventional extracts. In the FRAP assay, two hydrophilic extracts (C. papaya leaf ethanol extract (CPEE) and C. papaya freeze-dried leaf juice (CPFD)) showed relatively stronger reducing power compared to lipophilic extracts. Cell-based assays showed that CPFD significantly protected skin fibroblasts from H₂O₂-induced oxidative stress in both pre-and post-treatment. CPEE protected skin fibroblasts from oxidative stress in a dose-dependent manner while CPSCE significantly triggered the fibroblast recovery after treatment with H₂O₂. GC-MS analysis indicated that CPSCE had the highest α-tocopherol and squalene contents. By contrast, both CP hydrophilic extracts (CPEE and CPFD) had a higher total phenolic content (TPC) and rutin content than the lipophilic extracts. Overall, CPEs extracted using green and conventional extraction methods showed antioxidative potential in both cell-based and cell-free assays due to their lipophilic and hydrophilic antioxidants, respectively. Full article