Search Results (62)

The Baikal region, including areas with poor environmental conditions, has significant clean background zones. In the summer of 2023, we analyzed the physical and chemical parameters of aerosol particles with different size fractions at Irkutsk and Listvyanka monitoring stations. Reduced wildfires and minimal impact from fuel and energy industries allowed us to observe regional and transboundary pollution transport. A large data array indicated that, during the shift of cyclones from Mongolia to the south of the Baikal region, the concentrations of Na⁺, Ca²⁺, Mg²⁺, K⁺, and Cl⁻ ions increased at the Irkutsk station, dominated by NH₄⁺ and SO₄²⁻. The growth of the ionic concentrations at the Listvyanka station was observed in aerosol particles during the northwesterly transport. When air masses arrived from the southerly direction, the atmosphere was the cleanest. The analysis of 27 elements in aerosols revealed that Al, Fe, Mn, Cu, and Zn made the greatest contribution to air pollution at the Irkutsk station, while Fe, Al, Cu, Cr, Mn, and Ni made the greatest contribution to air pollution at the Listvyanka station. The dynamics of the investigated elements were mainly due to natural processes in the air under various synoptic situations and weather conditions in the region, although anthropogenic factors also affected the formation of aerosol composition wth certain directions of air mass transport. Full article

The low separation efficiency of conventional cyclone separators for sub-10 μm particles remains a critical challenge in Na₂S production processes. Previous optimization attempts have failed to reconcile economic feasibility with effective fine particle capture requirements. To address this industrial bottleneck, we propose an innovative secondary separation cyclone design tailored for next-generation Na₂S manufacturing systems. Our methodology synergizes computational fluid dynamics (CFD) simulations with experimental validation, achieving cost-effective development while ensuring numerical model reliability. Comparative analyses reveal significant improvements: under varying gas velocities, the novel design demonstrates 5.67–9.77% and 7.03–10.14% enhancements in 1–10 μm particle collection efficiency compared to standard and volute-type cyclones, respectively. Mechanistic investigations through flow field characterization elucidate the relationship between vortex dynamics and separation performance. This work provides a structurally optimized cyclone configuration with industrial applicability, as well as a validated hybrid experimental–computational framework that could inform solutions for fine particle separation across chemical processing industries. Full article

Water and wastewater monitoring plays a fundamental role in understanding the impact of anthropogenic activities on natural systems. Statistical process control (SPC) is a technique, among other statistical methods, for controlling systems and improving quality, with early applications in water quality and wastewater monitoring. This study aims to clarify the basic concepts of the tool, study how it has been used in water and wastewater monitoring, and highlight the limitations and opportunities for research. SPC still needs necessary adaptations and considerations to deal with the limitations of environmental data, especially in open systems such as water bodies. Future research should explore suitable statistical parameters and chart options, which could represent financial savings and effectiveness in monitoring, as, to date, the choice of these parameters has been based on monitoring studies conducted at the industrial level, where the variability in the monitoring variables is easily controlled. Finally, the tool shows promise for potential use in extreme events, such as droughts, major floods, storms (cyclones), and catastrophic environmental incidents (such as dam bursts), as long as the analysis is supported by a base period. Full article

Mangrove forests protect coastlines from erosion, enhance biodiversity, store carbon, and support coastal communities. These ecosystems rely on hydrological conditions. This paper reviews past, present, and future hydrological characteristics of Bangladesh’s Sundarbans to guide restoration and sustainable development. It examines historical and projected hydrological indicators, addressing knowledge gaps and suggesting strategies. Renowned for productivity, biodiversity, and socio-economic benefits, the Sundarbans depend on seasonal freshwater from the Ganges River. However, threats from climate change and human activities, including reduced freshwater flow due to India’s Farakka Barrage on the Ganges, rising salinity, cyclones, and pollution, endanger these ecosystems. The primary threat is mangrove destruction for alternate land use and reduced sediment supply due to upstream dam construction. Sea-level rise is a secondary concern, as a healthy Sundarbans delta could naturally accrete with adequate sediment input and mangrove growth. Sustainable management practices are critical, including maintaining upstream water flow, minimizing deforestation, and rehabilitating degraded areas. Alternative livelihoods and strategies addressing salinity rise are essential. Long-term approaches should adopt adaptive management and ensure sustainable resource use. Policy actions must regulate human activities, mitigate cyclone impacts, ensure freshwater availability, halt harmful industries, and promote awareness and surveillance. Protecting mangroves to reduce CO₂ emissions and advancing research are vital. Full article

In the chlorination industry, the reactor is a crucial equipment in which the chlorination reaction takes place. However, when the reactor is subjected to complex conditions such as high temperatures (e.g., >200 °C) and high pressures (e.g., >10 MPa), its structural integrity is significantly compromised, leading to severe safety issues. In this study, the fatigue life of a reactor is analyzed, with particular focus on the fatigue behavior of the cyclone separator under varying working conditions, such as changes in the temperature, pressure, and chemical environment. Using finite element simulations under steady-state conditions and the S-N curve from fatigue testing, the fatigue life and potential weak points of the reactor under different amplitudes and vibration frequencies are analyzed and predicted. This analysis is conducted using a combined simulation approach with ABAQUS and Fe-Safe software, v 6.14. This work also considers the periodic vibrations at the base of the cyclone separator within the reactor. Fatigue simulations under different vibration conditions are performed to further assess the fatigue life of the reactor, providing a theoretical basis for the optimization of design and ensuring operational safety. In addition, the influence of welding zones on the fatigue life is discussed. The results indicate that the welding defects and stress concentration may cause the welded joint to become a critical weak point for fatigue failure. Therefore, the fatigue performance of the welding zone should be carefully considered during the design phase. Full article

This article presents the X-ray fluorescence and X-ray diffraction analysis results and the granulometric composition of silicon production cyclone dust and its flotation enrichment products. The technology used for the preliminary preparation of cyclone dust before flotation enrichment is presented. The process of fine media flotation should include the careful preparation and reliminary processing of raw materials, otherwise it is difficult to achieve high flotation selectivity. Technological preparation necessarily includes the following stages: preliminary preparation of dust for flotation; repulping of prepared dust; sonochemical treatment of pulp; gravitational separation of sand phase; flotation separation. A structural diagram of the flotation separation technology used for the silicate and carbon phases of cyclone dust has been developed. As a result of this research, the characteristics of cyclone dust have been obtained, allowing us to draw conclusions about the possibility of its flotation processing and further use of the obtained products in the construction industry. The results of a study of carbon in a froth product have also been obtained. Carbon nanotubes have been discovered. Full article

A new type of elliptical cyclone separator has been proposed recently, but the flow field characteristics within the industrial device still need to be further investigated. In this paper, the characteristics of the flow field and particle motion inside the circular cyclone and the elliptical cyclone (with a long-to-short axis ratio of 1.2), with the equivalent hydraulic diameter of 300 mm, are comparatively analyzed using CFD methods. The results show that there is a significant change in the flow field distribution of the elliptical cyclone compared to the conventional circular cyclone. The static pressure gradient of the elliptical cyclone is anisotropic in the radial direction. The overall tangential velocity value is reduced, which reduces friction loss and makes the pressure drop of the elliptical cyclone significantly lower. More importantly, an acceleration/deceleration phenomenon of the airflow velocity occurs in the elliptical separator along the horizontal circumference, that is, the flow field is transformed into a circumferential fluctuating cyclonic field. This phenomenon induces an additional inertial separation effect that compensates for the unfavorable effects caused by the reduced centrifugal strength. Due to the coupling of centrifugal force and additional inertia effect, the residence time of small particles with a diameter of 1 micron in the elliptical cyclone is shorter, which helps to reduce the backmixing of particles and improves the separation efficiency of the elliptical cyclone. This study reveals the unique flow field characteristics of industrial elliptical cyclones, which is helpful to further understand the particle separation mechanism in the circumferential wave swirl field. Full article

This study evaluates the impact of the catalyst-to-oil (C/O) ratio in the 1 to 7 range on the catalytic cracking of vacuum gas oil (VGO). Experiments are conducted using fluid catalytic cracking (FCC)-type catalysts, in a mini-fluidized bench-scale Riser Simulator reactor invented at the Chemical Reactor Engineering Centre (CREC), University of Western Ontario. The CREC Riser Simulator replicates FCC industrial operating conditions such as temperature, species partial pressure, and reaction times. The results indicate that increasing the C/O ratio above 5 slightly impacts VGO conversion, increases light gases yield, decreases light cycle oil (LCO) yield, and stabilizes gasoline yield. These findings align with temperature-programmed desorption (TPD) data, showing how the retention of a larger number of acid sites at a C/O of 7 boosts light gas production and reduces LCO selectivity. These elevated C/O ratios also lead to higher coke formation. The results reported together with future studies conducted by our research team on the impact of higher catalyst flows, larger potential catalyst attrition, higher catalyst loading in the cyclones, and excess heat generated in the catalyst regenerator unit, are of critical value for establishing the impact of C/O ratios in the overall FCC refinery operation. Full article

Catalyst loss is a typical fault that impacts the long-term operation of the fluidized catalytic cracking (FCC) in the oil refining process. The FCC disengager is a critical place for separating the catalyst from oil gas. A fast and precise fault-cause judgment of catalyst loss is vital for avoiding catalyst loss failures. In this study, a novel fault judgment method of catalyst loss failures with quantitative criteria was established via the fault tree analysis (FTA) method, based on the relationship model between flow field signals and faults in the FCC disengager investigated by computational fluid dynamics (CFD). The FTA method defines three intermediate events: catalyst fragmentation, process fault and mechanical fault. In CFD results, it was found that the detailed fault reason can be inferred based on the changes in the characteristic parameters within the disengager. For example, when the catalyst loss rate of the FCC disengager may rapidly increase by a factor of around 200. Furthermore, the pressure drop of the cyclone separator decreases by around 35%, which indicates that the dipleg has fractured. The new fault judgment method has been applied in cases of catalyst loss in two industrial disengagers. The method accurately pinpointed the sudden reduction in inlet velocity and blockage fault at the cyclone separator as the main factors leading to catalyst loss faults, respectively. The judgment results are consistent with actual reasons, demonstrating the reliability of the method. This study could contribute to providing theoretical support and enhancing the accuracy for the diagnosis of catalyst loss faults, thereby ensuring the safe and stable operation of the FCC unit. Full article

The hydrogen plasma smelting reduction process has the potential to drastically reduce the CO₂ emissions of the steel industry by using molecular, atomic and ionized hydrogen as a reducing agent for iron ores. To increase the hydrogen and thermal efficiency of the process, a pre-reduction and pre-heating stage should be incorporated in a future upscaling of an existing HPSR demonstration plant within the scope of the “SuSteel follow-up” project to a target capacity of 200 kg/h of iron ore. The determination of the optimal process parameters is followed by a review of possible reactor types. A fluidized bed cascade, a cyclone cascade and a rotary kiln are compared for this purpose. Their applicability for the hydrogen plasma smelting is discussed, based on their fundamental design and operational procedures. Additionally, critical features of the different reactor types are outlined. A cyclone cascade with at least 3 stages is proposed to be the optimal reactor for pre-heating and pre-reducing the input material for the upscaled hydrogen plasma smelting reduction demonstration plant, based on the assessment. Full article

Cyclone separation is a widely utilized separation technique, which enables the self-rotation behaviors of particles in the internal flow field, in order to realize high-performance separation of mixtures. Oily sludges are solid wastes generated by the shale gas industry, which need to be properly treated for environmental protection. In the present investigation, we demonstrated that tuning the inlet flow pattern of the cyclone from linear flow to vortex flow is an effective approach to boost the rotation speed of oily sludge particles for obtaining significantly improved separation effects. Numerical simulations were carried out to investigate the influences of inlet flow pattern on the rotation behaviors of particles, which manifested in the rotation speed of particles being evidently increased up to 4500 rad/s when the inlet flow was tuned from a unidirectional pattern into vortex pattern. The effective rotation zone’s area was also found to increase significantly, with the area of the effective rotation zone enlarged by up to 400%. Further separation experiments on oily sludge were carried out using a cyclone equipped with a worm shell that generated vortex inlet flow with rotating blades. Separation results confirmed that the oily sludge was successfully purified by the cyclone equipped with a worm shell, which provided an extremely high oil removal percentage of 99.9%, showing a 49.1% enhancement in oil removal capability over the individual cyclone separation. Our investigations demonstrated an effective method for realizing oily sludge treatment and oil resource recovery by conventional cyclone separation. Full article

Cyclone separators are commonly employed in the mining, metallurgy and chemical industries due to their simple structure, easy maintenance and high recovery efficiency. However, with the wide application of cyclone separators, many problems have become exposed in their practical operation, restricting their development. Among these, wall erosion is becoming a significant problem. In this study, to resolve the problem of severe erosion on the walls, the Eulerian–Lagrangian framework was employed to investigate a cyclone separator with a draft plate at the inlet and to evaluate the effect of a draft plate with angles of 0°, 45° and 90° on the degree of erosion and the stabilization of flow fields. Moreover, after verifying the reliability of the numerical model via data from experiments, the characteristics of gas–solid flow were analyzed and the effects of the new structure on the degree of wear were investigated. The results demonstrated that unfavorable phenomena such as secondary flow and wall erosion generated during the operation could be mitigated by the draft plate. When the plate angle was 90°, the wall erosion was the lightest and the range of influence of the secondary flow was the smallest. When the plate angle was 45°, the comprehensive performance was the best, and there was a better balance between the energy loss and the degree of wall erosion. Therefore, the presence of the draft plate has a significant impact on the interaction of gas–solid phases in a cyclone separator. Full article

Multi-inlet cyclone separators can play a vital role in industrial processes by enhancing particle separation efficiency and minimizing energy consumption. This numerical study investigates multi-inlet cyclone separators to enhance their performance using a constant flow rate with a varying inlet height and width. By systematically varying the inlet height and width, three-inlet and four-inlet cyclone separators are developed and evaluated, termed 3 inlet-a, 4 inlet-a, 3 inlet-b, and 4 inlet-b. The findings reveal that increasing the number of inlets without changing the total inlet area does not improve the separation performance. However, strategic modifications to the inlet height and width significantly enhance the separation efficiency. Notably, the 3 inlet-a and 4 inlet-a designs achieve higher separation efficiencies at a 1.22 ${\mathrm{m}}^3$/s flow rate without increasing the pressure drop. Meanwhile, the 3 inlet-b and 4 inlet-b models demonstrate superior performances, with a higher separation efficiency and a pressure drop only marginally higher than the two-inlet design. This study provides valuable insights into the impact of inlet variations on cyclone separator performance, guiding future efforts to enhance the separation efficiency in multi-inlet designs. Full article

Hawke’s Bay in New Zealand was impacted by Cyclone Gabrielle in 2023, experiencing intense weather conditions and rainfall. Rivers and streams surged beyond their banks, displacing large amounts of sediment. The sewage treatment plant and industries in the Waitangi catchment, south of the city of Napier, were heavily impacted, making them potential sources of contaminants. The aim of this study was to investigate the risk of displaced sediments deposited south of Napier City, using bioassays and chemical analysis methods. Sediment samples were collected across a gradient between the coastline and the Waitangi Stream. The toxicity of chemically extracted or elutriate samples was assessed by Microtox^®, mussel embryo–larval development, and aryl hydrocarbon and constitutive androstane receptor yeast two-hybrid assays. Targeted chemical analysis and automated identification and quantification system (AIQS-GC) methods were used to identify contaminants. The elutriates showed low toxicity and the yeast assays showed levels of activity like those previously reported. Chemical methods confirmed historical contamination by DDT and its metabolites DDE and DDD, as well as by plant sterols. Overall, the toxicity and chemicals detected are what would be expected from a typical agricultural soil. The risk posed by the displaced sediment in the Waitangi catchment can be considered low. Combining chemical and bioanalytical methods was an effective approach to investigate the potential risks of post-disaster contamination. Full article

Cyclones are pivotal in mechanical process engineering and crucial in the complex field of separation technology. Their robustness and compact spatial requirements render them universally applicable and versatile across various industrial domains. Depending on the utilized fluid and field of application, both gas-based cyclones and hydrocyclones (HCs) are well established. Regarding HC design, enduring elongated flat cones have seen minimal alterations in shape and structure since their introduction over more than a hundred years ago. Experimental investigations regarding unconventional cone designs within scientific studies remain the exception. Therefore, this study focuses on alternative geometric configurations of the separation chambers and highlights their impact on separation and energy efficiency. To achieve this objective, different geometric shapes are investigated and retrofitted into HCs. The geometric foundation is derived from upcycled glass bottles. The repurposed bottles with a volume of 750 mL are used in conjunction with an inlet part, following the established Rietema design. Experimental tests are conducted with dilute phase separation, using 0.1–200 µm test particles in water. Comparisons between a bottle-based HC and a conventional Rietema design were conducted, establishing a benchmark against the standard. The findings revealed a noticeable correlation between separation efficiency and cone geometry. Conical designs demonstrated enhanced separation, particularly at lower volume flows. At the highest volume flow of 75 L min⁻¹, the best performing bottle cyclones showed separation efficiencies of 78.5%, 78.4% and 77.9% and therefore are in a competitive range with 78.0% efficiency, achieved using the commercial Rietema design. Minimal disparities in cut sizes were observed in terms of separation grade efficiency among the models tested. Variations in separation efficiency and fractional efficiency curves indicated nuanced differences in classification efficiency. Full article