Pneumatic Separation Research Articles

To the Theory of Grain Motion in an Uneven Air Flow in a Vertical Pneumatic Separation Channel with an Annular Cross Section

The possibilities of the action of uneven air flows on the grain material in the separating channels are still not used enough. The reason for this is the insufficient knowledge of the processes of interaction of the components of the grain material with an uneven air flow. The purpose of the research is to increase the efficiency of grain material separation according to aerodynamic properties by purposefully changing the diagram of air velocities in the channel sections using the actions of lateral and aerodynamic forces. The separation efficiency of grain material components was determined by trajectory analysis. The different geometry of the pneumatic separation channel was studied. The study of the distribution of air velocity and air pressure vectors in a vertical annular channel was carried out using the FlowVision software. It has been established that a change in the air velocity diagram can be implemented both by changing the geometric parameters of the channel and by additional distributed air supply through the perforation in the side walls of the pneumatic channel. Based on the analysis of the velocity field, an improved scheme of a pneumatic gravitational separator is proposed for separating grain material into three fractions according to aerodynamic characteristics.

Covering effect, size-fractionated, and stability of dry water with seawater@nano-SiO2: Electrochemical methods

The seawater dry water extinguishing materials formed by coating seawater with nano-SiO2 have greatly enlarged the application space of the seawater as a fire-extinguishing medium. Against the deficiencies in the evaluation of the size-fractionated and stability of dry water extinguishing materials, especially of the coating effect of nano-SiO2, this study designed an airflow size-fractionated system applicable to dry water materials and characterized the stability of dry water materials by electrochemical methods according to the pneumatic separation principle. The results showed that the grain size range of seawater@nano-SiO2 dry water extinguishing materials was 0.2–400 μm, and that the dry water could be divided into three intervals by granule size by adjusting the turbo-dynamo frequency and draught fan frequency of the airflow size-fractionated system. The electrochemical methods are applicable to describe the stability of the dry water extinguishing materials, and the gelatinization of core material can significantly make up for the deficiency that the core material of dry water tends to separate out over storage time. However, the stability of dry water is subject to granule size more than the gelatinization of the core material, and the dry water with big-size granules has optimal stability. Graded dry water is less corrosive to aluminum sheets, and the corrosion resistance to big-grained gel-dry water is optimal. The research conclusion can provide a technical basis for size-fractionated and covering effect characterization of dry water extinguishing materials and for type selection of storage media.

Development of a new technology for the production of food-grade soybean meal

A mandatory technological operation for the production of food-grade protein products is the dehulling of soybean seeds in order to increase the mass fraction of protein in the soybean oil cake or soybean meal. When the content of the processed hull in the soybean kernels decreases, more soybean kernels are removed and more soy oil is lost together with removed hulls. The aim of this work is to develop an effective technology of separating hulls from cracked soybeans with minimal oil losses and to determine the quality indicators of oil and soybean meal obtained from the kernel fraction. A pilot industrial plant with a maximum productivity of 1000 kg/h of soybean seeds has been developed including a crusher for dehulling soybean seeds, innovative pneumatic separators of the author's design for a two-stage separation of hulls from cracked seeds, a press-extruder for the production of oil and soybean meal from the kernel fraction. Effective technological modes of gradual separation based on innovative pneumatic separators of soybean hulls from cracked soybeans have been developed, which ensure the minimum hull content in the kernel fraction and minimal oil losses, namely. The specific load on the receiving sieve of the first stage pneumatic separator is 18,5 kg /(cm/h), the air flow rate in the upper part of the vertical aspiration channel of the pneumatic separator of the first stage is 3,31 m/s, and 2,71 m/ s in the second stage separator correspondingly. It is shown that when processing soybean seeds of similar quality, the hull content in the kernel fraction obtained at a pilot industrial plant according to the developed technology is lower in comparison with the literature data presented for a modern foreign line when other efficiency indicators are similar. When soybean seeds are processed by pressing method at a pilot industrial plant for dehullling based on the newly developed technology, unrefined premium soybean oil and soybean meal are obtained in accordance with the requirements of the relevant regulatory documents.

Pneumatic Separation of Fractions of a Polydisperse Gas Suspension in a Low-Velocity Flow

Pneumatic Separation of Fractions of a Polydisperse Gas Suspension in a Low-Velocity Flow

Substantiation of the main design parameters of the separation chamber of the pneumatic separator using various methods for calculating particle trajectories in the pneumoseparating channel

The article presents a study of the influence of methods for calculating particle trajectories in the pneumatic separation channel (PSC) on the design parameters of the separation chamber (length and height of the exit window), completed in 2013-2021. The field of air flow velocities and trajectories of spring wheat seed material components in the separation chamber of fractioning pneumatic seed separator was constructed. The initial data for the calculation were the information obtained earlier when calculating the trajectories of particles in the PSC by various methods. The location at the outlet of the channel, the value and direction of the particle velocity vectors were determined by computer modelling using the Solidworks Flow Simulation software package and two experimental and theoretical methods. They took into account the real velocity field of the air flow with and without grain load. The obtained values of the design parameters are compared with the results of experimental studies of the separation chamber. It should be noted that the methods of calculating the trajectories of grain impurity particles have a significant impact on the length of the separation chamber and the height of the exit window. The maximum length of the separation chamber of 0.75 m will be required for computer modelling of the velocity field in the PSC. Much smaller values of 0.50 m and 0.45 m will be required when calculating the trajectories of particles in the PSC using the velocity field obtained by experimental and theoretical methods. During the experimental study of the separation chamber during the cleaning of wheat seeds, the optimal length of the separation chamber was determined to be 0.55 m with an exit window height of 0.30 m. Thus, the values of the design parameters of the separation chamber obtained by experimental and theoretical methods are the closest to experimental data, which makes it possible to recommend them for use at the design stage of pneumatic separators.

Effect of Moisture Content and Variety on the Some Physical and Aerodynamic Properties of Sesame Seeds Relevant to Its Processing.

The physical and aerodynamic properties of black and white sesame were determined at Moisture Content(MC%) range of 8.5 – 30.6%(d.b).The major, minor, intermediate, arithmetic mean, geometric mean diameters and sphericity, projected area of the two varieties were 2.96 – 3.94mm, 1.47 -2.40mm,0.54 -1.26mm,1.66 – 2.50mm, 0.78 - 3.66mm and 26.53 – 93.45, 1.91 – 42.08mm2 respectively.The increase in MC resulted decrease in true density from 1038.61 – 994.93 kg/mm2 and 1039.61 – 998.47 kg/mm2 for white and black sesame seed respectively.The terminal velocity of white sesame seed ranged from 3.12 – 7.82m/s while black sesame seed ranged from 3.16 – 7.94m/s at MC range of 8.5 – 306% (d.b).The drag coefficient were 3.750.31 and 2.26 – 0.23 for white and black sesame seed respectively as MC ranged from 8.5 – 30.6% (d.b) while Reynold number varied from 2363.9 – 23067.3 and 3401.5 – 15121.6 for white and black sesame seed respectively at MC range of 8.5 - 30.6% (d.b).The properties of sesame seed determined varied significantly with variety and MC.This findings are the prerequisite in the design and selection of sesame seed separating machine. A pneumatic separator can be designed with provision for effective separation of undesired light material with average terminal velocity below 5.17m/s and 5.67m/s for white and black sesame seeds respectively.

Study on the segregation of brown rice and rice husks mixture in inclined chute flow

In the process of paddy hulling, the separation of rice husks and brown rice mixture is an indispensable stage. Usually, the mixture is transported along inclined chute driven by gravity from hulling system to pneumatic separation system to complete separation. To promote segregation of mixture is the key for improving separation effect. However, the segregation law and mechanism of two-property difference mixtures with small difference of particle size in inclined chute flow are still unknown. Hence, the transporting process of particles in inclined chute was explored by discrete element method (DEM) simulations and experiments. The results show that kinetic sieving mechanism still plays an important role in inclined chute flow of the mixture with small difference in the particle size. In the case of a certain flow distance and a small chute angle, providing more flow space along the depth direction for the particle flow can further improve the degree of segregation (DOS).

Computational fluid dynamics simulation and optimisation of the threshing unit of buckwheat thresher for effective cleaning of the cleaning chamber

Since a combined harvester’s grain-cleaning method depends on the pneumatic separation of grain and chaff, the airflow’s aerodynamic forces significantly affect cleaning efficiency. Based on buckwheat’s theoretical and mechanical properties, a new threshing drum with cleaning key parts was developed to reduce the variability of cleaning efficiency of buckwheat community threshers caused by inefficient threshing and accumulation of residue within the threshing system. This cleaning arrangement includes two wind speed inlets, each composed of four thin pipes of the same length as the threshing drum. The computational fluid dynamics modelling approach simulated the threshing and cleaning performance at different wind velocities within the threshing unit. The results showed that when the two inlets work simultaneously and adopt different wind speeds, i.e., 12 m/s and 15 m/s, the wind speed is higher than the critical value of the floating rate buckwheat kernel. Under this condition, the wind speed inlet area was increased, and the flow field velocity between the threshing drum and the concave grid plate ranged from 3.8 m/s-8.3 m/s. The flow velocity below the plate ranged from 7 m/s-15 m/s, higher than the floating speed of buckwheat kernels, which was the best choice. Based on these simulation results, a centrifugal fan was designed, which meets the buckwheat thresher’s cleaning performance.

Technological and design principles of grain quality improvement, taking into account natural and climatic conditions

The new and known technological and design principles for improving the grain quality of wheat vigorous varieties, have been substantiated. The proposed seven technological principles show the features of the use of new wheat varieties and their cultivation according to the best forecrops in the natural climatic conditions of the Krasnodar Territory, the features of seed preparation for sowing, soil cultivation, plant protection, and the application of fertilizers and the organization of harvesting. In the block of four design features, new technical solutions are proposed for the design of ejection-slot sprayers for seed treaters and spraying devices, the advantages of multifunctional machine units in wheat cultivation technology are substantiated, a design and technological scheme of a grain-harvester separator, modernized for cleaning the combed heap, the advantages of wheat harvesting technology with a harvester, combing growing crops, are presented in comparison with traditional technology. The possibility of increasing the wheat grain quality of a vigorous variety “Olkhon” from the 3rd to the 2nd class, due to harvesting with rotary separators, post-harvest grain ripening and sorting by pneumatic separators (PSM) and sieves with oblong holes, has been proven. The work has been performed at the Kuban State Agrarian University in 2015-2020. The purpose of the article is to justify new technological and constructive principles for improving the wheat grain quality.

THE SPREADING OF AIR FLOW VELOCITIES IN THE ASPIRATION CHANNEL MODEL FOR HIGHLY CLOGGED SOY PRODUCTS

Today soy is an indispensable agricultural crop. It is used in the food industry and feed production. Soy protein meal and mill cake increase the milk yield of cows by 7-10 percent and the fat content of milk by 0.2-0.3 percent, egg production of chickens by 6-12 percent. Due to the complexity of separation and imperfection of grain-processing machines, a large percentage of soybeans goes to waste, so the price of soybeans is high. To solve this problem, experimental studies were conducted with soy production waste on an air-gravity machine with an aspiration channel. The aspiration channel was upgraded with air flow dividers and accelerators installed on it. (Research purpose) The research purpose is testing the air flow dividers and accelerators on a prototypical sample of an aspiration channel with a vertically ascending air flow. (Materials and methods) A simulation model of the machine was created for research. 30 kilograms of the source material with a moisture content of 11.2 percent was used, which is a waste of soybean seed production, containing whole (35.74 percent) and crushed (51.5 percent) soy of an unspecified variety; and impurities: light (husk, pollen, dust - 10.12 percent), mineral (0.29 percent) and seeds of other crops (2.35 percent). (Results and discussion) The article presents the most successful configuration of air flow accelerators and dividers and air flow velocity. The optimal parameters of the length and width of the aspiration channel are presented. The article also presents graphs of the velocity distribution in a vertically ascending airflow. In the model of a pneumatic separation channel with flow dividers of the processed material and air flow accelerators, with an increase in the specific load, speed alignment is observed along the entire length of the channel at all heights. (Conclusions) The usage of dividers and accelerators solves the problem of stabilizing the interaction of the flows of processed material and air along the length and height of the channel, which will lead to an increase in the efficiency of the separation process.

Theoretical justification of pneumatic separation for copper sulfide ore enrichment

Theoretical justification of pneumatic separation for copper sulfide ore enrichment

Pneumatic separation system for collected seedlings using subdivided air streams

To adhere to the needs of automated supply of collected seedlings for mechanized grafting and cutting machines for enhancing their operational efficiency, herein, a separation system that uses subdivided air streams to separate the collected seedlings is developed. The separation system comprises a feeder for supplying collected seedlings, a seedling separator that uses subdivided air streams, a picking belt for the separated seedlings, a delivery unit for the separated seedlings, a pneumatic unit, and a control unit. To investigate the complete performance of separation, picking, and delivery of the separation system, several separation experiments were conducted to separate the collected Anthurium seedlings. The results show that the consistency of the moving direction of seedlings floated by subdivided air streams in the separation container and the moving direction of the picking belt have a significant effect on the picking of the separated seedlings by the picking belt. Moreover, the seedling supply timing of the feeder has a significant effect on the stability of the collected seedling separation rate during continuous separation. When this timing is such that the percentage of separated seedlings is 70%, the separation rate of continuous separation operation is 2.24 plant/s (the separation productivity is 8060 plants/h) with 0.12 CV. The operating conditions are 0.5 MPa separation pressure, 0.5 s nozzle operation time, and 60 mm seedling thickness in the separation container. Moreover, the staying times of the collected seedlings separated in the separation container are less than 2.5 min. Keywords: grafting, cuttings, pneumatic separation system, continuous separation, subdivided air stream, separation speed DOI: 10.25165/j.ijabe.20221502.6835 Citation: Jiang D L, Gu S, Chu Q, Yang Y L, Gu M Z, Yang Y. Pneumatic separation system for collected seedlings using subdivided air streams. Int J Agric & Biol Eng, 2022; 15(2): 84–92.

Two-aspiration air-sieve grain cleaning machines of new generation

The paper provides a review of fractional technologies developed by the authors, allowing to divide the grain heap coming from combines into 3 fractions: seed, fodder and unused waste. They are based on the use of two-aspiration air-sieve grain cleaning machines. The authors have developed a line of grain cleaners OZF-50/25/10 and OZF-80/40/20. Their productivity in terms of preliminary cleaning is 50 and 80 t/h, primary cleaning productivity is 25 and 40 t/h and secondary cleaning productivity is 10 and 20 t/h, respectively. The machines use an improved two-aspiration system with the ability to independently adjust the speed of air flows in the channels (patent No. 2298441), a new design of a sieve mill with a two-tier arrangement of sieves and setting in each tier sequentially two (at OZF-50/25/10) and three (on OZF-80/40/20) sieves. The mills implement a new sieve arrangement scheme (RF patent No. 43798), as well as original devices for a ball sieve cleaner and a pneumatic separation channel for the second aspiration. These devices make it possible to obtain the required quality of sieve cleaning and to isolate biologically defective grain in the pneumatic separation channel of the second aspiration. The separator for secondary cleaning of seeds SVS-30 is designed for the preparation of seeds of grain, spike, leguminous, industrial and oil crops when implementing fractional technology during post-harvest processing. Like all machines for secondary cleaning of seeds, the pneumatic system of the separator has two pneumatic separation channels for pre-screening and post-screen cleaning. A distinctive feature of the pneumatic system of the SV-30 separator is the consistent use of the same air flow in both aspirations. Fractional technology for processing grain heaps, implemented on an air-sieve separator, will increase the cleaning performance by 1.5…1.8 times with a minimum amount of mechanical stress on the seeds.

Плоскорешетные сепараторы с кольцевым пневмосепарирующим каналом

The search for the optimal variant of the structural ar-rangement of flat-screen separators by centrifugal-air sepa-rators with annular pneumatic separation ducts is a promis-ing direction in the development of new equipment. This will significantly improve the technological performance of grain cleaning plants. It may be considered a promising direction for such research. Therefore, it is necessary to look for new options for the layout of grain cleaning ma-chines to increase their technological efficiency. Several variants of technological schemes for the operation of ex-isting flat-sieve separators with a centrifugal-air separator with an annular pneumatic separation ducts are proposed. The technological process of the modernized grain clean-ing plant based on the A1-BIS-100 plantis described. The main parameters of the gravity transporting device are de-termined; they fully ensure the operability of the modern-ized plant.

Theoretical Studies of a Centrifugal Pneumatic Separator with Horizontal Air Flow

The article is devoted to the study of the motion of grain heap particles along the cylindrical surface of the separator. This article substantiates the relevance of post-harvest grain processing in the agro-industrial complex, proposes a design of a centrifugal pneumatic separator with a horizontal air flow, and describes the process of its operation. A mathematical model is obtained for the motion of a grain heap particle along the cylindrical surface of a grain separator with a centrifugal horizontal air flow.

Improvement of dissociation efficiency of limestone fines using vibration pneumoseparation

This paper presents the results of research into dissociation of minerals on a vibro-pneumatic separator composed of a series of cascade sections through which the classified material passes. Formation of the two-phase air flow in the working space of the separator is examined, and the causes of settling of small particles on the walls of the separator housing are analyzed. From the theoretical findings and experimental proof, dissociation efficiency of fines increases exponentially with growing frequency and amplitude of vibration effect on the body of the pneumatic separator. With the increasing amplitude and frequency of vibrations of the separator housing walls, the speed of particle settling on the walls decreases, which enhances the separation efficiency. The greatest effect is achieved when the vibrator is mounted on the front wall of the separator. This can be explained by turbulization of gas flow in the wall area due to the vibration effect exerted on it by the front wall. Vibration of the walls of the pneumatic separator leads to leveling of concentration of particles along the channel section and, consequently, to reduction in the number of fine particles settled. It is established that the maximum efficiency of separation of limestone waste from the Khomyakovsky Deposit by the boundary size of 1 mm is achieved with the following combinations of vibration parameters of the separator body: vibration amplitude A = 2.5 mm; vibration frequency ω = 250 s–1.

Improving the mechanical-mathematical model of pneumatic vibration centrifugal fractionation of grain materials based on their density

This paper has substantiated the mechanical-mathematical modeling of the process of fractionation of grain material into fractions. It has been established that this could optimize the process parameters and would make it possible to design new or improve existing working surfaces of centrifugal separators. A mechanical-mathematical model of the pneumatic vibratory centrifugal separation of grain material by density has been improved. This research is based on the method of hydrodynamics of multiphase media. The improved mechanical-mathematical model takes into consideration the interaction between the discrete and continuous phases of grain material by introducing conditions of interaction at the interface of these phases. In the hydrodynamic modeling of the movement of the circular layer of seeds, the coefficient of dynamic viscosity of discrete and continuous phases was taken into consideration. It was established that the pneumatic vibratory centrifugal separation process parameters are critically affected by the circular frequency of rotation of the cylindrical working surface, the frequency and amplitude of its oscillations. As well as such process characteristics as the airflow rate, dynamic viscosity coefficient, the average thickness of a grain material layer, and the mean density of its particles. Rational values for the technical parameters of the grain material pneumatic vibratory centrifugal fractionation process in terms of density have been determined by using the improved mechanical-mathematical model. The amplitude and oscillation frequency of the working surface are in the ranges A=(35…50)·10–5 m, ω=15.0...15.6 rad/s. The circular rotation frequency of the working surface, ω=24...25 rad/s. The airflow rate, V=2 m/s. It was established that using the improved mechanical-mathematical model of fractionation makes it possible to improve the performance of a pneumatic vibratory centrifugal separator by 9 %. At the same time, the effectiveness of grain material separation could reach 100 %.

A novel pulsated pneumatic separation with variable-diameter structure and its application in the recycling spent lithium-ion batteries.

In recycling of the spent lithium iron phosphorus (LiFePO4) batteries, the mechanical pretreatment is critical for relieving the pressure of the subsequent recycling process and reducing the cost of whole recycling process. In order to achieve the separation and concentration of the cathode materials, anode materials, copper and aluminum foils from spent LiFePO4 batteries, a novel pneumatic separation combined with froth flotation is designed in this research. A pulsated pneumatic separation with variable-diameter structure separator is used, through which 92.08% of copper and 96.68% of aluminum were recovered. In the pneumatic separation the movement of the copper and aluminum flakes can be described by an improved equivalent diameter method, based on the force analysis of the flaky particles. The froth flotation is utilized to recover the cathode materials and anode materials with the recovery of 92.86% and 83.21%, respectively. A mass balance and a technological route of the recycling process are provided finally. The present work provides a green and high-efficiency recycling process in which copper, aluminum, anode and cathode materials in lithium-ion batteries can be recovered respectively only by physical methods.

Research on Purification Technology of Ultra-Large Flake Graphite Based on Alkali-Acid Method

Graphite is a strategically scarce resource, and the preparation of high-purity graphite is the prerequisite and basis for the application of graphite. In order to determine the optimal purification technology parameters of an ultra-large flake graphite mine pneumatic separation ore with a fixed carbon content of 77.69%, a particle size of mainly 10 to 40 mesh, and main impurities of calcium carbonate, iron oxide and silica , two additional experiments of acid method and alkali method were added on the basis of alkali-acid method, to investigate the purification effect of different technological processes and acid leaching times on graphite raw materials, as well as to analyze the retention extent of different methods and alkali fusion temperature on graphite ultra-large flake structure. The results show that all three methods can increase the fixed carbon content of graphite to above 99%. However, compared with the acid method and the alkali method, the alkali-acid method can obtain high-purity graphite while also better protecting the graphite's ultra-large flake structure. The optimal fusion temperature is 400 °C, the optimal acid leaching time is 30% sulfuric acid thrice and 5% hydrofluoric acid once. After purification, the fixed carbon content of the product exceeds 99.97%.

Modeling of Aerodynamic Separation of Preliminarily Stratified Grain Mixture in Vertical Pneumatic Separation Duct

The productivity of most grain cleaning machines seems to be directly related to the efficiency of vertical pneumatic separation ducts. Nevertheless, improvement is accompanied by an increase in the load of the vertical duct, the design of which is limited by the width of the grain cleaning machines. This requires an increase in the thickness of the layer of grain mixture that enters the working area of the duct, which significantly worsens the conditions of separation of its components under the action of airflow. Particles of light impurities are unable to separate due to their retention by the grain medium. This reduces the quality of cleaning and requires appropriate scientific and technical solutions. The application of preliminary stratification of the granular mixture while increasing the concentration of light impurities in the top layer of the mixture seems to be a prospective method. The positive effect of the previous stratification on the intensity of redistribution of light impurity particles in the working zone has been theoretically considered and experimentally confirmed. Mathematical models were obtained to determine the trajectory of discussed particles, taking into account the previous stratification of mixtures, and the corresponding dependences were established. The influence of the initial coordination of the introduction of the particles of lightweight impurities, their sizes and densities, and technological and structural parameters of operation of the pneumatic separation duct were taken into account in the studies. The intensification of the process of cleaning grain from lightweight impurities in the working zones of pneumatic separation ducts of grain cleaning machines is theoretically substantiated.