Pneumatic Separation Research Articles

Calculation of particle trajectories in the pneumatic separation channel using various methods

The article presents the comparison testing of particle trajectories in the pneumatic separation channel (PSC) of the pneumatic seed separator SP-2F and its bend, calculated using computer simulation method and two experimental-theoretical methods. They are based on taking into account the real airflow velocity field. In the first variant, the velocity field was measured in an idle mode, in the second at the nominal grain load. The studies were carried out in a vertical PSC with a supporting grid divided into two parts by a partition wall. In the variant with the theoretical velocity field the trajectories of light and grain impurities in the first part of the PSC are shifted closer to the outer wall. In the second part of the channel, particles with hovering speed of 8.0...10.0 m/s are carried upwards, and with hovering speed of 11.0 m/s they fall down into the purified material. In the variant of the experiment in an idle mode, particles with the hovering speed of 7.0...10.0 m/s rise up in the second part of the PSC. In the variant with grain load, particles with the hovering speed of 7.0...9.0 m/s rise upward and ricochet off the inner walls of the PSC and a bend wall, and particles with the hovering speed of more than 10.0 m/s fall down into the purified material. In the variant of the experiment with the grain load, the particle velocity with the hovering speed of 5.0...9.0 m/s at the exit of the PSC bend is more evened as compared to other options - 2.3...2.7 m/s, and the velocity vector of most particles is directed at a lower angle to the horizontal: from 4 up from the horizontal to 17 down from the horizontal. The most accurate is the calculation of particle trajectories using the velocity field in the PSC at the nominal grain load. The results of the study can be useful in the theoretical substantiation of the design parameters of pneumatic systems of grain cleaning machines.

Innovative study on pneumatic separation of grain heap and economic feasibility of design versions

The paper is dedicated to the innovative analytical research in the field of pneumatic separation concerning the issues of grain heap feed for harvester-thresher cleaning, composition of tailings and the amount of grain. The problem of improving the separation of air-sieve cleaning of modern combines is of great current interest. The cleaning design with the use of pneumatic and inertia separator of small grain heaps for high-producing harvester-thresher is developed. The engineering study is conducted for the installation of the 8-bladed rotor above the chaffer sieve for experimental cleaning taking into account dimensional limitations and minimal alteration of the current air-sieve cleaning. The results of the study show the opportunity of better operation of the design of small grain heap cleaning with the application of pneumatic and inertia separator. The developed solutions make it possible to reduce grain losses and increase the harvester-thresher productivity level, as a result of which it is expected to achieve the economic effect assessed in the study.

Дослідження режимних характеристик гравітаційної напрямної кривої живильного пристрою

The rate of the feed velocity and specific load in the air separator are interrelated and require a rational approach to their choice, because reducing the rate of velocity increases grain flow thickness, which adversely affects the efficiency of grain separation in the separation zone, but limits separator performance. Based on the research of many authors, it was concluded that the feed velocity of grain material into the pneumatic separation channel should be in the range of 0.4… 0.6 m/s. Taking into account that using a feeder unit for multilevel grain input, the total thickness of grain flow is divided by the number of the involved levels of input. The main condition is to ensure a single layer of grain feed at the velocity at which the most intense release of light impurities. Therefore, the purpose of the study is to identify rational parameters of the guide gravitational surface of the feeder unit with the provision of appropriate performance characteristics of the grain flow during its multilevel feeding into the pneumatic separating channel. As a result of experimental research, the dependences of the modes of movement of grain material on the gravitational guide curve on its main parameters, namely, the length of the acceleration section Lp, its angle α and the radius of the arcuate section r. On the basis of the carried-out research parameters of a gravitational guide surface at which a single-layer mode of movement of grain material for a range of specific loadings is reached are established qB = 250 – 500 kg/hour. Accordingly, for the conditions of movement of grain material with a thickness of one grain with the velocity of feeding into the pneumatic separation channel vв = 0.5…0.6 m/s, the rational parameters of the guide gravity curve for cereals with the internal friction coefficient φтер = 0.47…0.73 there are: the length of the acceleration section Lp = 0.2 m, the angle of its inclination α = 33° and the radius of the arcuate section r = 0.15 m.

The technological aspect of soybean seed separation

The results of a study on the purification of soybean seeds by the combined use of a gravity column with a zigzag channel formed by a cascade of installed combs and a pneumatic separation channel with a vertically ascending air flow and with narrowing partitions installed in it are presented.

A study on the possibility of improving sulfide ore preparation characteristics using the pneumatic separation process

The size, density of the particles and their shape play a significant role in the effectiveness of the pneumatic separation process. An experiment held using a lab machine revealed that the shape of the particles affects their warping from the air-flow. Research has shown that the airflow produced with the flat or narrow side of the ore which are flat and have a large form factor are more likely to be affected by the warping process. The impact of the ore shapes on the results of separating the pieces in terms of their density during the pneumatic separation process can be decreased by producing a structured feed-through into the air-flow using the flat side or by improving the previously selected ore pieces of a flat shape.

A low-cost and high-value reinforcing filler for styrene butadiene rubber fabricated by a pneumatic separation technique from coal gasification fine slag

A novel filler for rubber was prepared by deep processing of coal gasification fine slag (CGFS) using an airflow sorter. Five processed CGFS samples with different sizes and carbon contents were obtained. The effects of particle size, unburned carbon, and surface properties of CGFS on the comprehensive properties of filled styrene butadiene rubber (SBR) were investigated. The mechanical properties were improved with decreasing CGFS size, and the curing and mechanical properties exhibited better performance owing to the unburned carbon. Unburned carbon can improve the dispersion properties of the filler and the compatibility between the matrix and filler. The best values for the curing characteristics and mechanical properties of SBR appeared when CGFS-S2 and CGFS-S3 were used as the fillers, respectively. Heavy calcium carbonate (CaCO3) particles were used as a comparative filler, and the results demonstrated that CGFS particles have the potential to replace CaCO3 in rubber. A novel method for preparing coal gasification fine slag (CGFS) samples utilized as a reinforcing filler for the SBR matrix through an efficient pneumatic separation technique has been demonstrated. The superior filler–rubber interfacial interaction can contribute to significant reinforcement in the comprehensive performances of composites by the addition of CGFS series fillers into the SBR matrix. CGFS particles have great potential for application in rubber composites, and a new strategy of using CGFS as fillers has been established.

Optimisation of a multi-duct cleaning device for rice combine harvesters utilising CFD and experiments

As the grain-cleaning process in a combine harvester relies on pneumatic separation of the grain and chaff, the aerodynamic forces created by the airflow have a large impact on the cleaning performance. Therefore, to optimise a multi-duct cleaning device in a rice combine harvester, First, the equivalent resistances for the different fan ducts were quantified with a resistance model of fluidised grain and an airflow resistance model for the cleaning sieve. Perforated plates with different opening ratios were designed to simulate working loads. A computational fluid dynamics (CFD) model was validated by comparing simulation results with hot-wire anemometer measurements. The effects of working loads on airflow velocity and volume distribution at the ducts, and total pressure distribution inside the fan were studied in simulation and experiments. After integration of the designed multi-duct fan into the cleaning system, airflow measurements inside the cleaning shoe were made and cleaning performance tests were carried out on a test bench. The ideal airflow velocity within the cleaning shoe was investigated by correlating airflow velocities at different measuring points and analysing the cleaning performance. An evaluation of this multi-duct cleaning system in the field showed large improvements in terms of the grain sieve losses ratio and grain impurity ratio compared to a combine harvester with the single-duct cleaning system. The corresponding grain sieve loss decreased from 2.46% to 0.08%, while the grain impurity ratio decreased from 4.78% to 0.511%.

Aspects of the Process of Sorting European Black Pine Seeds

Research Highlights: Seed separation criteria and the optimal parameters of sorting devices were described. Background and Objectives: Seeds are often sorted into fractions which are sown separately to promote uniform seed germination and seedling emergence. Therefore, the aim of this study was to determine the correlations between the basic physical properties of European black pine (Pinus nigra J.F. Arnold subsp. nigra) seeds for the needs of planning seed sorting operations. Materials and Methods: Black pine seeds were divided into 5 batches representing individual parent trees, and the physical properties (terminal velocity, thickness, width, length, angle of external friction, mass) of each seed were determined. The measured geometric parameters and seed mass were used to calculate the respective indicators for each seed. The values of the analyzed parameters were used to plan the seed separation process. Results: The average values of the basic physical properties of seeds were determined in the following range: Terminal velocity—8.32 to 8.73 m s−1, thickness—2.24 to 2.27 mm, width—3.34 to 3.44 mm, length—5.87 to 6.08 mm, angle of external friction—28 to 32°, mass—18.8 to 20.0 mg. Seed mass was most highly correlated with terminal velocity, and it was least correlated with the angle of external friction. Conclusions: The results of this study indicate that black pine seeds should be sorted with the use of pneumatic separators or, alternatively, mesh sieves with longitudinal openings. These sorting devices separate seeds into fractions characterized by similar seed mass, which delivers both economic and environmental benefits in nursery practice.

Mechanical properties and morphology of coal gasification fine slag glass bead‐filled acrylonitrile–butadiene–styrene (ABS) composites

ABSTRACTCoal gasification fine slag glass beads (CGFSGBs) were processed via an efficient pneumatic separation technique. CGFSGB products (CGFSGB‐S1, CGFSGB‐S2, and CGFSGB‐S3) with different sizes were acquired. The heavy calcium carbonate (CaCO3) was used as comparative filler. Effects of particle size and geometric shape on mechanical strengths, flow properties, and solid density of filled acrylonitrile–butadiene–styrene (ABS) were investigated. The mechanical strengths of composites decreased with increasing CGFSGB weight fraction, while MFR and solid density increased. The mechanical strengths were found to increase with decreasing CGFSGB size, and spherical surface of the CGFSGB is more beneficial to improve interface adhesion strength than square surface of the CaCO3. The flow property analysis showed that the ABS/CaCO3 composites have better fluidity and the advantages in the processing energy consumption. However, the incorporation of CaCO3 resulted in the higher solid‐state density. In summary, CGFSGBs have the potential to replace CaCO3 in the ABS market. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48601.

Nonlinear modeling proposal for the germination performance of Paspalum regnellii seeds: a species with forage potential in Brazil

Finding qualified standard plants is an essential requirement in the search for high-quality pasture, fact that involves knowledge about the performance of the assessed seeds. Therefore, the aim of the present study was to evaluate the influence of seed weight on the germination behavior of Paspalum regnellii seeds through the logistic growth model. The adopted values were taken from an experiment conducted in 2016 under laboratory conditions. A pneumatic separator was used to select four seed classes, depending on the weight of one thousand seeds namely: Extra light, light, middle and weighted. The logistic model was adjusted to data about the germination rate of each class, and the parameters were compared through the F test. Germination rates between classes were compared based on recorded parameters and on model critical points. The logistic model adjusted well to the values and made it possible to use the parameters and critical points of the curve to describe the germination process. In addition to have low germination rate, seeds in the light-weight batch demanded longer to complete this process. Based on estimates about the parameters and the critical points of the model, the weighted-weight seeds were superior in terms of quality than seeds in the other batches, since they recorded higher germination rate in a shorter period-of-time.

Theoretical study of pneumatic separation of sugarcane bagasse particles

Sugarcane bagasse is a byproduct generated at sugarcane mills after sugarcane juice extraction. Studies on the enzymatic hydrolysis of fine pneumatic classified particles at ambient equilibrium moisture content have shown good cellulose to glucose conversion without any extra pretreatments as milling, enzymatic, acid or a combination of these, which is one of the current hydrolysis process bottlenecks. Avoid such pretreatments is extremely important for reducing process costs. Based on previous work, this study performed a theoretical investigation of bagasse particles' separation aiming a better understanding of this phenomena permitting development and improvement of equipment used for it. Numerical simulations were carried out using ANSYS Fluent® and Rocky® DEM software, which modelled separation experiments based on computational fluid dynamics and discrete element method, respectively. The comparison between simulation and actual experimental results showed that the model is predictive and can be extended to several processes that use the fluidisation of sugarcane bagasse, such as drying, pyrolysis, and gasification. The studied simulation models can also serve as a basis for fluidisation simulations of other biomasses.

Combined mechanical process recycling technology for recovering copper and aluminium components of spent lithium-iron phosphate batteries

The recycling processes of spent lithium iron phosphate batteries comprise thermal, wet, and biological and mechanical treatments. Limited research has been conducted on the combined mechanical process recycling technology and such works are limited to the separation of metal and non-metal materials, which belongs to mechanical recovery. In this article the combined mechanical process recycling technology of spent lithium iron phosphate batteries and the separation of metals has been investigated. The spent lithium iron phosphate batteries monomer with the completely discharged electrolyte was subjected to perforation discharge. The shell was directly recycled and the inner core was directly separated into a positive electrode piece, dissepiment, and negative electrode piece. The dissociation rate of the positive and negative materials reached 100.0% after crushing when the temperature and time reached 300 °C and 120 min. The crushed products were collected and sequentially sieved after the low-temperature thermal treatment. Then, nonferrous metals (copper and aluminium) were separated from the crushed spent lithium iron phosphate batteries by eddy current separation with particle size -4 + 0.4. The optimised operation parameters of eddy current separation were fed at speeds of 40 r min-1, and the rotation speed of the magnetic field was 800 r min-1. The nonferrous metals of copper and aluminium were separated by the method of pneumatic separation. The optimal air speed was 0.34 m s-1 for the particle-size -1.6 + 0.4 mm and 12.85-14.23 m s-1 for the particle-size -4 + 1.6 mm. The present recycling process is eco-friendly and highly efficient and produces little waste.

Pneumatic separation and recycling of anode and cathode materials from spent lithium iron phosphate batteries.

A novel approach to recycling of copper and aluminum fragments in the crushed products of spent lithium iron phosphate batteries was proposed to achieve their eco-friendly processing. The model of pneumatic separation that determines the optimal airflow velocity was established using aerodynamics. The influence of the airflow velocity, and the density and thickness, and their ratios, of the aluminum and copper fragments on pneumatic separation were evaluated. The results show that the optimal airflow velocities of copper and aluminum fragments with and without the electrode materials are 3.27m/s and 1.67m/s, respectively. The accuracy and reliability of the present model was verified using a pneumatic separation experiment. It is concluded that graded pneumatic separation is unnecessary for the crushed particle size more than 9 mm. The experimentally determined optimal airflow velocity of the copper and aluminum fragments with and without the electrode materials is 3.3m/s and 1.7m/s, respectively. The mass fractions of the copper and aluminum fragments upon removal of the electrode materials after pneumatic separation are 97% and 96%, respectively, and both with the electrode material achieve 97.0%. The theoretically obtained optimal airflow velocities have good agreements with the experimentally obtained ones.

REMOVAL OF MINERAL IMPURITIES FROM AFTER - HARVESTING RESIDUES OF CORN

Due to the energy crisis, special attention is paid to the production and use of biofuels. After-harvesting residues of corn (AHRC) may become a perspective source of energy for grain dryers. The following components of the AHRC are distinguished: stem, leaves, rod and wrapper of the cob. The AHRC is about 55...60% of the total weight of the plant. The annual harvest of corn grain is more than 20 million tons. The calorific value at burning of wheat straw is 14.4 MJ/kg, AHRC -15.7 MJ/kg. For comparison, the calorific value of wood on average is 14.24 MJ/kg, and natural gas is 33.5 MJ/m3 [1]. Using the AHRC can significantly reduce the need for imported gas. One of the directions of the use of plant raw materials as fuel is the production of granules [2]. The technology involves purifying raw materials from impurities, crushing and granulation. For a similar scheme, granulated feeds are produced. When picking up a harvester, following transportation and reloading, various contaminants, including mineral impurities in the form of stones, fall into the green mass. Having hit the crusher stones lead to damage to parts of the crushing mechanism, an accident and even an explosion. Clearing straw from impurities in agriculture is carried out on pneumatic separating machines [3]. But in the technical literature there is no data available to the separation of mineral impurities from the AHRC. As a result of the experiments, it was found that leaves and stalks can be separated by air from large stones, and the separation ofrods from stones is complicated. Under the influence of air flow, the rods are rotated along the pneumatic separating canal and unfolded by a long axis in parallel with the air flow, which leads to a decrease in the area of the midel section and to the reduction of the aerodynamic resistance. Therefore, to provide the required force acting on the core from the air stream, they increase the air velocity, which causes the capture and joint movement of the stones. To improve the separation process of the AHRC from the stones, it is necessary to develop a nutritional mechanism of the separator, in which to predict the possibility of orientation of the rods in the pneumocaps to the long axis across the air flow. This will enable you to reduce the air velocity required for separation and increase the difference in aerodynamic forces acting on the stones and rods. Accordingly, at the same time, the energy intensity of the pneumatic separation process will decrease and the efficiency of separating the AHRC from the stones increases. The separation of small stones smaller than 3 mm only by air is impossible, since they are picked up by the air flow that moves at the speed necessary for separating the stems (7.5...12.5 m/s). For the separation of small stones, it is proposed to use grid separators with combined air purge. For the complete separation of mineral impurities from corn cores, it is recommended to use hydro-separators.

Increase of seeding material quality of agrarian crops by the pneumatic electric separator

A detailed analysis of technical means and methods of seeds separation, as well as the research results of domestic and foreign authors, have proved that one of the perspective methods for getting of high quality seed material is the pneumatic and electric separation.The analysis of research works and the modern technical level of pneumatic separators showed that insufficient attention was paid to the study of aerodynamic separation of small-seed crops, especially, cereal grasses. By the conditions of separation in a vertical pneumatic channel the cereal crops change the area of the midlength section as to the air flow forces, and the probability was increased of getting of seeds with germs to a biologically defective seed without germs. To increase the quality of pneumatic separation one can by the selective orientation of seeds in mixture with longer axis perpendicularly to the flow of air. It is possible to achieve these conditions by the additional force action on seeds (as particles). The response of this force action could be different for a healthy seeds (with germs) and for a non-viable (without embryo) or a weed seed. Such a force effect on the particles of small-seed crop mixtures can be realized by creating of a homogeneous electric field in a separation channel. This requires a theoretical and experimental study of force action on particles during the process of separation, also justification of parameters and operating modes of the pneumatic electric separator. This study is the preconditions for design improvement of the pneumatic electric separator.

Виробничі випробування пневматичного сепаратора на попередньому очищенні насіннєвих сумішей цибулі

Виробничі випробування пневматичного сепаратора на попередньому очищенні насіннєвих сумішей цибулі

Статистична оцінка якісних показників пневмосепарації при багаторівневому введенні зерна

Статистична оцінка якісних показників пневмосепарації при багаторівневому введенні зерна

Improvement of the sunflower seed separation process efficiency on the vibrating surface

The study of the sunflower seed separation process during its movement on the vibrating surface has been carried out in two stages. The first (theoretical) stage has been implemented in the software package STAR-CCM + using the corresponding physical models. The second stage is the conduct of experimental research on a pilot sample with a base of vibrating pneumatic PVS table. As a result of numerical simulation and experimental studies of the sunflower seed separation process during its movement on the vibrating surface, we have determined the dependences of the change in the distribution coefficient, productivity and power consumed by the vibrating pneumatic separator from the seed supply, the inclination angles of the vibrating surface, the frequency and amplitude of its oscillation and the velocity of the airflow V. The statistical analysis has shown that the correlation coefficient between the theoretical and experimental dependencies in the variation of the values of the factors in the given range is 0.88-0.92. The technological and constructive scheme of the adaptive vibrating pneumatic separator with rationally defined regime parameters (seed supply, airflow velocity, deck oscillation frequency, deck inclination angle) has been developed basing of the obtained theoretical and experimental dependencies, using the software which is based on the created algorithm, allowing to perform the technological process of sunflower seed mixtures separating by volume density with higher productivity and quality.

Metallurgical slags processing

Technological schemes have been developed for the processing of blast furnace slags and a mixture of metallurgical slags – complex mineralogical composition waste from various industries (blast-furnace slag; steel-smelting slag; slag resulting from special steels production, thermal power plant ash) – to obtain a number of valuable materials possessing ecological and economic benefits. According to the scheme of waste blast-furnace slags processing, provision has been made not only to separate the magnetic fraction, but to obtain building slag, binding and micro-filling materials for the production of high-strength concrete as well. The block-modular equipment, where the uniform single-type metal construction of each block is connected to the complex proper with cantilever belt conveyors, makes it possible to install the block on the required surface of an industrial site without any bedding, and to move it, in case of need, during a shift with minimal use of materials handling equipment. The complex includes blocks of primary screening, small screening and crushing, pneumatic and magnetic separation. The parameters and modes of the process equipment operation, which is part of the complex, are regulated over a wide range making it possible to ensure high processing efficiency with variable properties of the raw material. The technological scheme of complex processing of a mixture of metallurgical slag dumps, besides obtaining building materials, provides for a set of technological measures for magnetic-gravitational separation of raw materials, which allows to ensure up to 95% metal content in the resulting scrap (magnetic and non-magnetic), and the predicted extraction of scrap not less than 90...92%

Comparison of Spherical and Non-Spherical Objects in Cyclonic and Uniaxial Flow Regimes

This paper uses the Muschelknautz method to model the cyclone separation of chestnut shell and kernel fragments simulated as a square plate and sphere respectively. Because of the opposing geometry of the kernel and shell particles, a new framework is derived using CFD simulations to predict the drag coefficient of the shell particle as a function of orientation and Reynolds number. The drag coefficient of the shell is approximately proportional to the sine of the orientation angle, squared. Despite this, particle orientation remains relatively constant for all practical geometric and velocity parameters within a cyclone, as implied by the assumptions used in this paper. The results from the separation model show that the tangential velocity is almost 86 times greater than the radial velocity of the particle beneath the vortex finder. Consequently, the full frontal area of the particle is not exposed to the radial flow and the particles are not separated effectively by drag force. An experimental separation efficiency of 28.5% compared to an efficiency of 0% predicted by classical cyclone theory, indicates that the shell particles could be re-entrained at the base of the cyclone. This suggests that cyclones do not utilise the differences in drag between particles. The simulation of chestnut kernel and shell particles in a uniaxial flow field (such as occurs in pneumatic separation) shows that it is theoretically possible to achieve a significantly larger separation efficiency when compared to cyclones.