Single Cyclone Research Articles

Analysis of the influence of dust particles in the peanut pickup harvester with a self-designed axial-flow dust-fall box on its dust suppression performance

The atmospheric particulate pollution poses a serious threat to human health and ecological environment. The dust particle pollution caused by the operation of agricultural machinery is becoming increasingly severe and the peanut pickup harvesters are widely used in agricultural operation. Therefore, it is necessary to reduce the concentration of dust particles in the work of peanut pickup harvesters. In this study, a self-designed dust-fall box composed of multipleaxial flow cyclone tubes in parallel was integrated with the peanut pickup harvester. Based on the CFD-DPM model, simulation analysis was conducted to explore the effects of different inlet velocities, different numbers of swirling blades, and two types of exhaust port on the dust removal performance of the cyclone. The Box-Behnken design was used to determine the optimal structural parameters of the axial flow cyclone. The influence of the pressure distribution and velocity variations of the internal flow field on the dust removal efficiency of the two schemes was simulated and analyzed. Thereafter, a reasonable parallel scheme of multiple axial flow cyclone tubes in the dust-fall box was determined. The drone was used to monitor dust in peanut harvesting operations, and dust particle concentrations at 8 detection points under varying working conditions were recorded. The distribution and diffusion rules of dust in harvesting operations were explored through cluster analysis, and the test data obtained were compared with numerical calculation results to verify the accuracy of numerical calculation. The results showed that for a single axial flow cyclone, when the inlet wind speed was 6 m/s to 8 m/s and the number of swirling blades was 4, the structural parameters of the cyclone separator had significant influence on the separation efficiency. The influencing factors ranking in descending order were cylinder diameter, cylinder length, and exhaust pipe insertion depth, respectively. To be more precisely, the separation efficiency was best when the cylinder diameter was 60 mm, the cylinder length was 150 mm, the insertion depth of the exhaust pipe was 50 mm and the cone angle was 20°. It was more reasonable to use 8 axial flow cyclone tubes in parallel, and the maximum separation efficiency can reach 84.21 %. Field operations showed that the numerical calculation results were similar to the actual harvesting process. The dust particle concentration in the peanut harvesting operation equipped with a dust-fall box was always lower than 10 mg/m3. The dust particle concentration was the highest at the rear of the whole machine and the lowest near the cab. Compared conventional harvesters, the harvester with a dust-fall box reduced its dust particle concentration by 64.37 %; the concentration of 30 μm dust particles was reduced by 69.31 %; the dust particle concentration at the rear of the whole machine also effectively reduced. This study can provide reference for controlling dust emissions during peanut harvesting operations and agricultural machinery harvesting operations.

Numerical Simulation Study of Combustion under Different Excess Air Factors in a Flow Pulverized Coal Burner

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

Climate network analysis of extreme events: Tropical cyclones.

Climate networks based on surface air temperature data are analyzed to identify distinct signatures of tropical cyclones, which appear in the Indian Ocean. These networks, which are percolating networks, show an abrupt phase transition in the order parameter and the susceptibility during cyclonic events. The behavior seen is compared for the months October-November 2016, when three successive cyclones, viz., cyclone Kyant, cyclone Nada, and cyclone Vardah, were seen, and compared with a year where a single cyclone, cyclone Ockhi, was seen in December 2017. All these cyclones were seen in the Bay of Bengal. The microtransitions, i.e., the locations of jumps in the order parameter, for these two cases show distinct patterns. The signatures of the cyclones can be seen in other quantities like the node degrees and their geographic distributions and other network characterizers. We also compare these with a cyclone, cyclone Ashoba (2015), seen in the Arabian Sea where cyclones are rarer. The networks also show the signatures of precursor behavior, which has implications for further analysis.

Numerical analysis of single SC-50-800 and SC-50-500x2-x4 group centrifugal cyclones: efficiency comparison

Centrifugal cyclones are important devices used to separate solids or liquids from gas streams using centrifugal forces. They are widely used in various industrial processes and air and gas purification systems. In this work, numerical modeling and study of the efficiency of cyclones of various configurations are carried out: single cyclone SC-50-800, group cyclones SC-50-500x2 and SC-50-400x4. To conduct the study, the engineering software package Comsol Multiphysics 6.1 was used with the addition of the Flow Simulation module, specialized for modeling hydrodynamic processes. To simulate turbulent flows, the v2-f model was chosen, which is often used in the case of swirling flows. The computational experiment was carried out at a constant air flow rate of 4500 m3/h. Based on the obtained numerical data, an analysis of the effectiveness of various cyclone configurations was carried out. The results of the study show that the operating efficiency of group cyclones significantly exceeds the efficiency of single cyclones. This is confirmed by analysis of separation parameters and comparison of performance indicators of various cyclone configurations. The data obtained can be useful for the design and optimization of gas stream purification systems in various industrial and environmental applications.

Analysis of parameters technological gas emissions neutralization during the sintering process of phosphorite agglomerate

This study analyzes the specific properties and technological parameters of gas emissions from chemical-energy processes [1], considering the volume and content of toxic components, as well as the operating experience of gas emission purification systems at existing phosphate plants. A three-stage system of apparatuses is studied for gas purification: an ensemble of single cyclones, foam aggregates irrigated with aqueous caustic soda solution. It is established that cyclones are the most suitable apparatus for dry gas cleaning, and that their diameter should be no more than one meter to increase the efficiency of cleaning. It has been demonstrated through scientific research that when cleaning phosphorite sintering gases, which have a volume exceeding the capacity of a single cyclone, it is necessary to use group cyclones. These are several cyclones combined into one group with a common hopper. It is recommended that the cyclone speed be increased by approximately 50% in comparison to the standard speed, which contributes to an increase in the efficiency of the separation of impurities in the purified gas.

Experimental investigation on the separation characteristics of the novel combined separator

The cyclone separator is widely used as the efficient steam separation device for the nuclear reactor. In this study, a novel gas–liquid separator that can realize efficient and stable gas–liquid separation under a wide range of working conditions is designed. The separator is organically combined with an axial cyclone separator and a tangential cyclone separator. The axial cyclone separator performs the role of rectification and pre-separation, and the tangential cyclone separator ensures separation performance. The variation in the gas–liquid interface characteristics and separation characteristics of cyclone separation under different inlet flow rates are investigated. Compared with the single tangential cyclone separator, the separation deterioration range of the novel separator is significantly reduced. The addition of the pre-separator effectively broadens the operating conditions for efficient separation. The pressure drop of the novel separator is reduced by more than 50 %. Based on the separated flow model, the relationship between the separation pressure drop ratio and dimensionless number is established, and the prediction method for the pressure drop is put forward with the prediction accuracy within ±10 %, which provides reference for the practical application of the novel separator.

Investigation into the Flow of Gas-Solids during Dry Dust Collectors Exploitation, as Applied in Domestic Energy Facilities – Numerical Analyses

The paper presents the results related to the simulation of dust-separating tangential cyclones: single cyclones of various geometries, and an axial multi-cyclone with fixed geometries and components. Its goal was to apply low-cost analyses for cyclones in industrial realization. Therefore, the presented research was applied with simulation methodology as a problem of Computational Fluid Dynamics. The models were analyzed using SolidWorks Flow Simulation software. The presented dust collectors are real-life objects, applied in industrial facilities. For a multi-cyclone, the increase in the number of blades, from 5 to 8, together with the change in the angle of a blade’s pitch i.e., 30° and 45°, resulted in dust concentration along the internal walls from just 10% for 5 blades up to c.a. 37.5% for 6 blades, and c.a. 50% for 8 blades, whereas the dust concentration in the device’s central part equals c.a. 20% for the last option. The model validation draws attention to the potential applicability of the software in flow issues alongside common and more complex numerical environments.

The effect of inlet velocity, gas temperature and particle size on the performance of double cyclone separator

In this present study, the effect of inlet velocity, gas temperature on pressure drop and the effect of particle size on the collection efficiency under different operating conditions are demonstrated for a double cyclone separator, which mainly consists of a 2D2D and 1D3D cyclone in series arrangement. The experiment of pressure drop measurement for different inlet gas velocities in the range of 11–23 m/sec are conducted and it is observed that the pressure drop increase with an increase in gas velocity, which is also validated with CFD results using RSM model and well-established theoretical models. The numerical simulation is also performed for different gas temperature in the range of 300–1100 K. The prediction shows that the pressure drop decrease gradually with increasing the gas temperature, which also gives a better agreement with empirical correlations. The collection efficiency has been estimated for different particle size in the range of 1–10μmat u = 23 m/sec, by CFD approach. It is noted that the efficiency of single cyclone is very poor for fine particles (<5μm) but adding a 1D3D cyclone in series with a 2D2D cyclone separator, the pressure drop is reduced more and the overall separation efficiency is improved in a comprehensive way.

Experimental Study of a PowerCore Filter Bed Operating in a Two-Stage System for Cleaning the Inlet Air of Internal Combustion Engines

Small dust grains cause a higher intensity of increase in the flow resistance of the fibrous filter bed, which, due to the established value of the permissible resistance, results in a shorter period of operation of the air filter and the vehicle. At the same time, the mass of dust per unit of filtration area takes on smaller values. Such a phenomenon occurs in the two-stage “multicyclone-baffle filter” engine inlet air filtration system. The main objective of this study was to experimentally determine the mass of dust retained per unit of filtration area (dust absorption coefficient km) of the PowerCore filter bed operating under two-stage filtration conditions, which cannot be found in the available literature. The original methodology and conditions for determining the dust absorption coefficient km of a PowerCore filter bed operating under two-stage filtration conditions are presented. Tests were carried out on the characteristics of filtration efficiency and accuracy, as well as on the flow resistance of a filtration unit consisting of a single cyclone and a PowerCore test filter with an appropriately selected surface area of filter material. During the tests, conditions corresponding to the actual conditions of vehicle use and air filter operation were maintained, including filtration speed and the dust concentration in the air. The experimentally determined dust absorption coefficient of the PowerCore research filters operating in a two-stage filtration system took on values in the range of km = 199–219 g/m2. The dust absorption coefficient km of the PowerCore research filter operating under single-stage filtration conditions reached a value of km = 434 g/m2, which is twice as high. Prediction of the mileage of a car equipped with a single-stage and two-stage “multi-cyclone-partition” filtration system was carried out, showing the usefulness of the experimentally determined dust absorption coefficients km.

Numerical study of the efficiency of single and group centrifugal cyclones

Centrifugal cyclones are devices used to separate solids or liquids from gas streams using centrifugal forces. They are widely used in various industrial processes, as well as for purifying air and gases from contaminants. The work carries out numerical modeling and study of the efficiency of single cyclone SCN-50-800 and group cyclone SCN-50-400x4. The study was carried out in the engineering software package Comsol Multiphysics 6.1 using the Flow Simulation add-on, designed for modeling hydrodynamic processes. The v2-f model, which is very often used in swirling flows, was chosen as the turbulence model. The computational experiment was carried out at the same productivity of 4500 m3/h. Based on the obtained numerical data, it is shown that the efficiency of group cyclones is significantly greater than that of single cyclones.

Geomorphological response of sandy beach to tropical cyclones with different characteristics

Tropical cyclones (TCs) play important roles in the evolution of beaches. The response of beaches to a single tropical cyclone (TC) has been well reported, however, few studies have compared the responses of the same beach to TCs with different characteristics. Taking Haiyang Beach in the northern China Seas as a case study, the beach profiles before and after two TCs, Lekima and Bavi, which passed through the west and east sides of the study area, were investigated. The beach exhibited erosion at the upper foreshore and minor deposition near the mean high water level (MHW) after Lekima with subaqueous sandbars formed in the nearshore zone, whereas all the beach profiles showed little changes after Bavi. A high-resolution FVCOM model was established and eleven sensitive experiments were conducted to simulate hydrodynamic changes induced by TCs with different tracks, intensity and duration. Then the Xbeach model was used to display the beach evolution due to different TCs conditions. It is found that the significant storm surge and strong seaward bottom current induced by landward wind of the TCs passed through the west side of the study area should responsible for the beach profile changes. Negligible storm surge rise and landward bottom current related to the seaward wind of eastern path TCs can only result in little change of the beach. Swell contributes most to the wave height while has less effect on the beach changes. In this study, we conclude that the effects of TCs on beaches are primarily dependent on relative position of a beach and TCs’ tracks.

Effect of number of inlets on performance and flow field of large‐scale cyclone separators

AbstractThe performance and flow field of large‐scale cyclones with different inlet numbers were investigated by using computational fluid dynamics methods. The results show that the efficiency, pressure drop, and performance factor of cyclones increase with the increase in the number of inlets, and the quadruple inlet cyclone having the best overall performance is supposed to adopt. The number of inlets of the cyclone increases, the tangential velocity increases, and the short‐circuit flow rate decreases; however, when the number of inlets is greater than 2, both variations are lessened. In this study, the vortex eccentricity of the quadruple inlet cyclone is the smallest, the vortex eccentricity of the double and triple inlet cyclone is comparable, and the vortex eccentricity of the single inlet cyclone is the most significant.

Multiple convective storms within a single cyclone on Saturn

Here we describe a cyclone at 50∘N in the atmosphere of Saturn that was the source of eight separate convective storms. The storm clouds that appeared bright in scattered sunlight were identified using images from the Cassini Imaging Science Subsystem (ISS) and ground-based telescopes. The Cassini Radio and Plasma Wave Science (RPWS) instrument detected Saturn Electric Discharge (SED) signals from the lightning within the storms, which were correlated to the sudden appearance of bright storm clouds in and surrounding the cyclone. Using the number and flash rate of SEDs we infer the duration and intensity of the storms. Although previous storms have been observed to erupt from within cyclones, the cyclone studied here is unusual in that it survived six storms before being disrupted by the seventh and strongest storm. An eighth storm occurred in the remnant of the disrupted cyclone. We conjecture that the anticyclonic circulation generated by the seventh storm was enough to overwhelm the cyclone’s gradient wind balance.

Effect of inlet volute wrap angle on the flow field and performance of double inlet gas cyclones

In response to the divergent understanding of double inlet cyclone performance in the literature, the effect of inlet volute wrap angle on the performance and flow field of double inlet cyclone separator was studied by Computational Fluid Dynamic (CFD) method. The results showed that the inlet volute wrap angle can affect the comparison results of the single and double inlet gas cyclones with the same total inlet cross-sectional area and velocity. 0° and 90° volute double inlet improved the efficiency mainly by separating particles below 10 μm, while 180° volute double inlet had no separation advantage for any particles, so the symmetrical double inlet does not always improve the efficiency, and the appropriate inlet volute wrap angle should be selected according to the actual situation, otherwise, the expected performance requirements of the symmetrical double inlet cyclone cannot be achieved. Compared with the flow field, it is found that the inlet volute wrap angle changed the tangential velocity of the symmetrical double inlet cyclone separator, thus changing the performance.

Simultaneous Spray Drying for Combination Dry Powder Inhaler Formulations.

Spray drying is a particle engineering technique used to manufacture respirable pharmaceutical powders that are suitable for delivery to the deep lung. It is amenable to processing both small molecules and biologic actives, including proteins. In this work, a simultaneous spray-drying process, termed simul-spray, is described; the process involves two different active pharmaceutical ingredient (API) solutions that are simultaneously atomized through separate nozzles into a single-spray dryer. Collected by a single cyclone, simul-spray produces a uniform mixture of two different active particles in a single-unit operation. While combination therapies for dry powder inhalers containing milled small molecule API are commercially approved, limited options exist for preparing combination treatments that contain both small molecule APIs and biotherapeutic molecules. Simul-spray drying is also ideal for actives which cannot withstand a milling-based particle engineering process, or which require a high dose that is incompatible with a carrier-based formulation. Three combination case studies are demonstrated here, in which bevacizumab is paired with erlotinib, cisplatin, or paclitaxel in a dry powder inhaler formulation. These model systems were chosen for their potential relevance to the local treatment of lung cancer. The resulting formulations preserved the biologic activity of the antibody, achieved target drug concentration, and had aerosol properties suitable for pulmonary delivery.

On the Evolution of the Gulf of Mexico Loop Current Through Its Penetrative, Ring Shedding and Retracted States

How the Gulf of Mexico Loop Current (LC) transitions from penetrative to ring shedding to retracted configurations remains an active research topic. Satellite altimetry suggests a set of states, some more persistent than others, identified as Campeche Bank Anchoring, West Florida Shelf Anchoring, Extended, and LC Ring, plus transitional phases. Histograms show that the most frequent states are Campeche Bank Anchoring and West Florida Shelf Anchoring. Two canonical evolutions are defined. The first is a transition from Campeche Bank Anchoring to West Florida Shelf Anchoring. The second is a transition from Campeche Bank Anchoring to Extended to LC Ring. Common to both are cyclonic eddies. The first canonical transition requires cyclones formed both east and west of the LC, acting as pincers far enough south to dislodge the LC from the Campeche Bank. The second has a single cyclone, formed on either side of the LC, that cuts through either from the east, thereby not dislodging the LC from the Campeche Bank, or from the west, but too far north to dislodge the LC. Notable is the importance of the Campeche Bank and Florida escarpments. Cyclones may generate either by instability or downslope perturbation, but whether these lead to protracted penetration, or just jostling from one anchoring state to another, depends on where they are generated and how they combine to shed a LC Ring. Thus, these findings suggest that furthering understanding and prediction requires observations and analyses over the two escarpment regions and the LC domain south of about 25°N.

Polar and mid-latitude vortices and zonal flows on Jupiter and Saturn

Zonal flow on Jupiter and Saturn consists of equatorial super-rotation and alternating East–West jet streams at higher latitudes. Interacting with these zonal flows, numerous vortices occur with various sizes and lifetimes. The Juno mission and Cassini’s grand finale have shown that the zonal jets of Jupiter and Saturn extend deeply into their molecular envelopes. On Jupiter, the vast majority of low and mid-latitude jovian vortices are anticyclonic, whereas cyclones appear at polar latitudes. Cassini mission observations revealed a similar pattern on Saturn; its North and South polar vortices are cyclonic, whereas anticyclones occur at mid-latitudes. We use the recently developed code Rayleigh to run high-resolution simulations of rotating convection in 3D spherical shells. Four models are presented that result in dynamical flows that are comparable to those on the giant planets. We confirm previous results, finding that deep convective turbulence can explain the structure of jets. However, the latitude and the strength and depth of stable stratification can modify jet morphologies and affect the formation and dynamics of vortices. Lower latitudes favour shallow anticyclonic vortices that form due to upward and divergent flow near the outer boundary. These anticyclones are typically shielded by cyclonic filaments associated with downwelling return flow. In contrast, a single polar cyclone, or clusters of cyclones form near the poles. All of our simulations have this global pattern; a strong preference for shallow anticyclones in the first anticyclonic shear zone away from the equatorial jet (corresponding to the region of the Great Red Spot on Jupiter and Storm Alley on Saturn), cyclonic and anticyclonic vortices at higher mid-latitudes, and a deeply seated cyclone or cyclone clusters at each pole. Our results show that Juno and Cassini observations of cloud-level flow can be explained in terms of deep convective dynamics in the molecular envelopes of Jupiter and Saturn.

The Numerical Modeling of Gas Movement in a Single Inlet New Generation Multi-Channel Cyclone Separator

The work of traditional cyclones is based on the separation of solid particles using only the centrifugal forces. Therefore, they do not demonstrate high gas-cleaning efficiency, particularly in the cases where gas flows are polluted with fine solid particles (about 20 µm in diameter). The key feature of a new-generation multi-channel cyclone separator’s structure is that its symmetrical upgraded curved elements, with openings cut with their plates bent outwards, make channels for the continuous movement of the gas flows from the inflow opening to the central axis. The smoke flue of the vertical gas outflow is located near the cover of the separating chamber. The present work is aimed at studying the applicability of two various viscosity models and their modified versions to simulate aerodynamic processes in an innovative design for a multi-channel cyclone separator with a single inflow, using the computational fluid dynamics. The research results obtained in the numerical simulation are compared to the experimental results obtained using a physical model. The main purpose of this study is to provide information on how the new design for the multi-channel cyclone affects the distribution of gas flow in the cyclone’s channels. The modified viscosity models, k-ε and k-ω, and computational meshes with various levels of detailed elaboration were analyzed. The developed numerical models of a single-inlet multi-channel cyclone separator allow the researchers to describe its advantages and possible methods of improving its new structure. The developed models can be used for simulating the fluid cleaning phenomenon in the improved fourth-channel cyclone separator and to optimize the whole research process.

Ocean Affects from Severe Weather Systems in Coastal Areas

Severe weather systems can generate large waves and storm surges which can cause many fatalities in coastal areas. In extreme circumstances a single cyclone caused up to 500,000 fatalities in the Bay of Bengal in 1970. Adaption by authorities in that region from evacuations and construction of storm shelters have significantly reduced the number of such fatalities there. The effects of Hurricane Sandy in 2012 in New York City and surrounding areas is examined to show how ocean effects can cause many casualties. Scrutiny of a European storm shows how a slight error in analysis can fail to detect a deadly increase in intensity which caused many fatalities. World record wave height events are examined, and the historical Australian east coast events are investigated. The impacts from long period waves emanating from distant storms are shown to be a forecasting problem.

Geo-ecological impact assessment of severe cyclonic storm Amphan on Sundarban mangrove forest using geospatial technology

We report the damage caused by Amphan, a category five tropical cyclonic storm, to the ecology and shoreline of the Sundarban mangrove ecosystem, located in India and Bangladesh. In this study, net shoreline movement (NSM) combined with vegetation indices, such as normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI), were used to analyze land use and land cover changes and the position of the shoreline in pre- and post-cyclone periods. The results show that the cyclone wreaked havoc in the Sundarban mangrove ecosystem, causing dangerous impacts on vegetation and severe erosion along the shoreline. The impact on the Sundarban mangrove forest, shown by NDVI and EVI values, indicates that the mangrove vegetation suffered degradation and fragmentation. Dense and moderately dense mangrove tree cover area shrank from 77% to 34%, less dense and sparse cover increased from 20% to 63%. More than 68% of shoreline transects registered signs of erosion, with mean shoreline change and erosion rate measurements of −31 m and −48 m, respectively. As a result, agricultural lands and aquaculture ponds suffered inundation, leading to crop damage. A single cyclone episode can damage mangrove cover by knocking down tall trees, killing more salt-sensitive mangrove species such as Sundari, and leads to increased man-animal encounter. We argue that post-cyclone biodiversity loss and ecosystem services loss should be analyzed in tandem and synchrony with human and livestock casualty and economic damage assessment.