Hopper Outlet Research Articles

Study the Flow Capacity of Cylindrical Pellets in Hopper with Unloading Paddle Using DEM

The hopper is an important piece of basic equipment used for storing and transporting materials in the agricultural, grain, chemical engineering, coal mine and pharmaceutical industries. The discharging performance of hoppers is mainly affected by material properties and hopper structure. In this work, the flow capacity of cylindrical pellets in the hopper with the unloading paddle is studied. A series of numerical simulation analyses with the aid of the discrete element method (DEM) platform are carried out. Then, the discharging process is illustrated, and the flow capacity of pellets in the hopper is analyzed by the mass flow index (MFI), the dynamic discharging angle (DDA) formed in the discharging process and porosity among pellets. Furthermore, the effect of parameters such as hopper half angle, rotation speed of the unloading paddle and outlet diameter of the hopper is investigated. The results show that MFI increases with an increase in hopper half angle or outlet diameter and a decrease in rotation speed. Meanwhile, DDA and porosity decrease with the increase in the hopper half angle or outlet diameter and the decrease in the rotation speed. Finally, the MFI ~0.24 is identified as the criterion to distinguish the mass flow from the funnel flow for the hopper with an unloading paddle, and the optimization results are decided as follows: hopper half angle greater than 60°, outlet diameter greater than 60 mm and rotation speed between 45 rpm and 60 rpm. These results should be useful for providing a theoretical reference for the optimization design of feeding devices for swine feeders.

Advancing the Engineering Approach to Improving the Quality Cracking Efficiency of Palm Nut Crackiing Machine

A Palm Nut cracking machine with an improved beater configuration was developed to effectively crack Palm Nuts of various species and sizes. This research aim at improving the quality of the Palm kernel recovered at relatively low cost during Palm kernel oil production. Durable materials were acquired locally to fabricate the machine for ease of usage and maintenance, also to make it affordable for small and large scale processors. Basic features of the machine are; hopper, electric motor (prime mower), cracking chamber, cracking beater and discharge outlet. The design of the cracking drum and beater configuration was based on the impact force required to crack the Palm Nut which is a function of Palm Nut shear strength. A 5 hp electric motor was selected based on the power required to effectively operate the machine. The machine was tested with “Tenera” varieties, three nut sizes (14.5, 22.15 and 29.43mm) and five speeds (970, 1200, 1450, 1750 and 2430rpm). Result shows that the change in machine speed significantly (P<0.05) affects all the machine performance irrespective of the Palm Nut size and variety, which agrees with the report of several other researchers. The obtained optimum machine performance values are 14,874 nuts/h, 89.5%, 98% for the machine capacity, quality performance efficiency and cracking efficiency for Tenera variety. The best crop and machine parameter for the optimum performance of the Palm Nutcracker are 29.43 mm and 970 rpm, nut size and machine speed. It was concluded that the overall performance of this developed Palm Nut cracking beater was effective because it fell within the range of 80 to 98% efficiency.

Development of a clogging probability model in simplified geometry for fast reactor flow blockage analysis

The occurrence of flow blockage accident in fuel assemblies is considered as one of the primary challenges to be addressed in liquid metal fast reactors. Flow blockage accidents are primarily caused by the accumulation of solid particles, such as corrosion products, wire spacer fragments, and chemical products between liquid metal and impurities like air or water. To better understand the mechanisms underlying the blockage formation, a project consisting of several series of simulated experiments is currently underway at Sun Yat-sen University and Harbin Engineering University. In the initial stage of the project, experimental study was conducted to investigate the influence of particle characteristics on the probability of clogging by discharging various solid particles into a reducer pipe. Preliminary experimental analyses revealed the formation of an arch structure at a specific location on the pipe. This arch structure causes the granular flow to cease, resulting in blockage. Based on the accumulated experimental database, in this study an empirical model is developed to predict the clogging probability, taking into account the above-mentioned influential parameters. The model demonstrates a reasonable agreement with experimental results within the current range of conditions, encompassing variations in the ratio between hopper outlet size and particle size, particle capacity, particle static friction coefficient, and particle release height. Although further extension of the empirical model is inevitably necessary under more realistic reactor conditions, such as incorporating realistic sub-channels, irregularly shaped particles, or a loop with a liquid phase, it is expected that the model will be beneficial for the improved design of sub-channels and safety analysis of fast reactors.

Study on fine powder discharged from hoppers modified with insert

The use of inserts in the hopper provides a reliable way to improve the quality of powder flow. In this work, glass beads, fluidized catalytic cracking catalyst (FCC), lignite and polyvinyl chloride (PVC) were used as experimental materials and the flow properties of powders were characterized by the FT4 powder rheometer and the PT-X powder tester. Discharge experiments on a Perspex hopper at a laboratory scale are presented in this paper, comparing the flow characteristics of fine powders discharged from a plain hopper and from hoppers modified with the use of inserts of different geometries. Effects of insert and powder properties on powder flow rate are discussed. A mechanism model is developed to describe the hindering effect to the discharge consequent to the powder expansion at the hopper outlet. Mechanisms of insert on powder flow are analyzed. It is demonstrated that the higher flow rates of the hopper operating with a solid insert are due to the anticipated expansion of the material generated by the presence of the insert. The hopper with a hollow insert shows a flow sequence and the values for the powder flow rates are averaged values between two regimes. Based on understanding above mechanisms, powder flow rates for plain hopper and hoppers modified with insert are successfully predicted.

Wedge-Shaped Hopper Design for Milled Woody Biomass Flow

The bioenergy industry has been challenged by unstable flow and transport of milled biomass in material handling operations. Handling issues such as hopper clogging and auger jamming are attributed to knowledge gaps between existing handling units designed for bulk solids and their suitability for milled biomass with high compressibility. This work investigates various flow behaviors of granular woody biomass in wedge-shaped hoppers. Hopper flow physical experiments and numerical simulations are conducted to study the influence of the critical material attributes and critical processing parameters on the flow pattern, arching, and throughput. The results show that (1) the preferred flow pattern, mass flow, can be achieved by controlling the material’s internal friction angle, hopper inclination, and hopper wall friction; (2) hopper arching, governed by the competing gravity-driven force against flow resistance from material internal friction and material–wall friction, can be controlled by the hopper wall friction angle and the inclination angle; and (3) flow throughput can be accurately estimated from our empirical equation with inputs of hopper outlet geometry and particle-scale to bulk-scale material attributes. This study elucidates woody biomass flow physics and provides guidance for industrial equipment design.

Three-dimensional clogging structures of granular spheres near hopper orifice

The characteristic clogging structures of granular spheres blocking three-dimensional granular flow through hopper outlet are analyzed based on packing structures reconstructed using magnetic resonance imaging techniques. Spheres in clogging structures are arranged in a way with typical features of load-bearing, such as more contacting bonds close to the horizontal plane and more mutually-stabilized contact configurations than packing structures away from the orifice. The requirement of load-bearing inevitably leads to the cooperativity of clogging structures with a correlation length of several particle diameters. This correlation length being comparable with the orifice diameter suggests that a clogging structure is composed of several mutually-stabilized structural motifs to span the orifice perimeter, instead of a collection of independent individual spheres to cover the whole orifice area. Accordingly, we propose a simple geometric model to explain the unexpected linear dependence of the average size of three-dimensional clogging structures on orifice diameter.

Studying Grain Flow Immersion into Liquids of Various Densities Based on the Methods of Experiment Design

Introduction. In addition to grain, a grain heap of rye may contain poisonous ergot sclerotia. Modern grain cleaning machines do not isolate ergot sclerotia in one technological process because of the similarity of physical properties in linear dimensions. Isolation of ergot sclerotia from rye grain in one technological process is possible through the use of aqueous solutions of inorganic salts. The purpose of the study is to determine the optimum elevation of the loading hopper relative to the liquid surface. The data obtained contribute to increasing the quality of the technological process of the machine being developed. Materials and Methods. The paper considers the delivery of rye grain flow from the loading hopper outlet into the liquid by varying the specific grain load, liquid density and the delivery height. To set up the experiments, the experiment design methods have been used. The experimental data have been processed using the statistical package Statgraphics Plus 5.1. Results. The estimation of the effective elevation of the loading hopper outlet relative to the liquid surface when delivering grain flow has been carried out. There have been obtained regression models for the fraction of grains, which did not submerge and rose up to the liquid surface with air bubbles. Discussion and Conclusion. It has been found that the density of the aqueous salt solution has a significant effect on the percentage of grains, which did not submerge and rose up to the liquid surface with air bubbles. The smallest values of at different density of the liquid and specific grain load are achieved at a grain delivery height 56.0 ∙ 10–3 m.

On the design of conical hoppers for spent coffee grounds: Moisture content and particle-size effects

Spent coffee ground (SCG) is a food waste with promising potential for reuse in pilot-to-industrial scale processes provided that storage and handling issues are overcome. Here some key bulk and flow properties of SCGs were determined with FT4 rheometer, for powders with different particle-size distribution (249.1 ≤ dV ≤ 583.1 μm) and moisture content (2.8% ≤ MC ≤ 62.5%). These properties were used to evaluate the design of mass-flow silo hoppers following the classical Jenike theory. The SCGs flowability worsened by decreasing dV and increasing MC, with indexes between 1.09 ≤ HR ≤ 1.92 and 2.5 ≤ FF ≤ 15.0. The minimum hopper inclination and outlet diameter ranged from 9.9° to 17.1° and 0.40–1.00 m. A sensitivity analysis for the hopper design was performed, and a densification equation was coupled to Jenike's method to ease future hopper designs for SCGs with different properties. Ultimately, the results showed that careful consideration must be given to dV and MC to design effective devices to handle SCGs.

Justification of vibrating hopper hole parameters during fine grained bulk material unloading

Purpose. The leakage process of the fine grained bulk material (BM) from the unloading hopper is considered. As known the BM behaviour during the unloading process is directly related to the material stress state (active or passive) inside the hopper, which depends on the physical and mechanical bulk material properties, as well as hopper geometric parameters. At the boundary of the transition from the cylindrical part to the conical part of the unloading hopper hole, the horizontal stresses that precede the leakage of the material increase sharply. The use of vibration reduces horizontal stresses in the hopper and thus improves the bulk product fluidity. Also, the use of vibration reduces the probability of the free-fall arch formation over the outlet. Therefore, the present paper is aimed at developing the mathematical model of the fine grained bulk material flow under the vibration action from the conical hopper hole. Methodology. It is used one of the methods of studying the BM behavior, namely the analysis of the stress state of the conditionally stationary (pseudo-stationary) layer of the product and the force balance equation in the free-fall arch is made for further study of the geometric parameters of the unloading hole. Findings. In this paper, the mathematical model of the BM behavior in the conical hopper hole is developed. Since the most determining factor influencing the hopper productivity is the outlet diameter, so based on the developed model, it is established relationships that allow determining all parameters that affect the diameter. Graphical dependences are obtained, which allow to estimate the influence of the angle inclination of the hopper hole walls on the value of the hopper outlet size at active and passive stress states. The dependence of the diameter of the unloading hopper hole on the BM properties is also established. The BM properties directly affect the initial shear resistance of the material. The influence of vibration on the unloading hole geometry is presented. Originality. The pseudo-immobile layer of bulk product is considered in the developed mathematical model, and it is investigated how vibration affects the BM behavior in this layer. Practical value. The practical value of this paper lies in the possibility of further mathematical modeling of the influence of the BM properties, hopper geometric dimensions and vibration on the product behavior in the material leakage process from the hopper. The results of the studies, presented in the form of graphs, can be used during the vibrating hopper design and the selection of rational modes of hopper operation.

Theoretical Underpinnings of the Parameters of Device for Cleaning Grain from Ergot Sclerotia

Introduction. The grain collected by a combine contains not only full-weight grain, but also weeds, including harmful ones, which include toxic ergot sclerotia. Existing grain cleaning machines cannot provide complete separation of toxic ergot sclerotia during a single technological process, because of the similarity of physical properties. A complete separation of ergot from grain in one technological process is possible by density using aqueous solutions of inorganic salts. Therefore, an urgent issue is the development of a machine for separating harmful impurities in a wet way. Materials and Methods. We consider the fall of grains of rye, wheat, barley and oats, which have a shape close to ellipsoidal, from the outlet of the loading hopper into a liquid with a density of 1.0; 1.05; 1.10 and 1.15 ∙ 103 kg/m3. Theoretical explorations were undertaken for grain density (1.2...1.5) ∙ 103 kg/m3, a length (5.0...10.0) ∙ 10–3 m, a width (1.4...3.6) ∙ 10–3 m and thickness (1.2...3.5) ∙ 10–3 m by mathematical modeling methods using the laws of mechanics and hydrodynamics. Results. For the development of a machine for a wet separation of harmful impurities, the height of the location of the outlet of the loading hopper relative to the surface of an aqueous salt solution was estimated. The formulas are obtained for determining the minimum height required to overcome the Archimedean ellipsoid grain force, surface tension forces and fluid hydrodynamic resistance, taking into account the law of conservation of energy. Discussion and Conclusion. It was found that the minimum height of the loading hopper outlet location relative to the liquid surface depends on the orientation of the grains at the moment of entering it, their linear dimensions and density, as well as the density of an aqueous salt solution. The height of the outlet of the loading hopper, necessary for guaranteed overcoming of the surface tension of the liquid by all grains, is 57.1 ∙ 10–3 m.

Mathematical Description of the Influence of the Bunker Outlet on the Grain Motion in the Microwave Convective Area

One of the environmentaly friendly methods of drying and decontamination of grain is its processing in microwave-convective installations. The efficiency of using the microwave field depends on the uniformity of its distribution in the grain processing zone. This is provided by the design features of the microwave core and waveguides. The uniformity of grain movement in the microwave field zone is important. It is important that the grain is moved in the microwave convective zone by hydraulic movement. In this case, the grain passes through zones with different intensity of the microwave field sequentially and the grain processing is uniform. (Research purpose) The research purpose is in making a mathematical dependence of parameters of the hopper outlet on the movement of grain in the microwave convective zone. (Materials and methods) The article presents the parameters of the outlet that ensure the grain flow without forming static arches in accordance with the method of calculating outlet bins. Fluctuations in humidity for different crops of processed grain will not lead to a violation of the grain flow process. The resulting equation for changing the height of the dynamic arch, depending on its location in the height of the hopper, allows to determine the uneven flow of grain from the hopper outlet. (Results and discussion) When unloading grain, there is an uneven flow in the right and left halves of the hopper, relative to the central axis. When only one hopper is unloaded, 0.84 kilograms more wheat is unloaded from its left half than from the right. This difference leads to uneven and reduced efficiency of grain processing in the microwave-convective zone. (Conclusions) To ensure the uniformity of grain processing in the microwave convective zone, it is necessary to improve the mechanism of grain flow from the outlet of the hopper.

Investigation of discharge characteristics of rod-shaped particles in a hopper: Experimental and numerical studies using polygonal/polyhedral DEM

In this work, the discharge of numerous polygonal particles in a hopper was investigated numerically and experimentally. To this end, a polygonal/polyhedral DEM model is proposed and implemented to simulate hopper operation in 2D and 3D. The results of a conservation test show that the proposed algorithm conserves energy better than the CP algorithm owing to its straightforward contact calculation. The model then is adopted to simulate the discharge of rod-shaped particles in hopper. Lab-scale experiments were also conducted for DEM model validation. To evaluate the influence of particle shape, outlet opening, and discharge slope angle, rod-shaped particles with triangular, square, pentagonal, and hexagonal cross-sections were used in the experiments and simulation. The results show that the discharge rate of non-spherical particles was significantly affected by the shape of particles, and inter-particle packing property was found to have stronger influence than rolling-related properties, such as roundness or moment of inertia. Conditional clogging phenomena of particles were observed, and the tendency of particle clogging was enhanced by high initial loading, narrow outlet opening, and low slope angle of the hopper outlet. The criteria conditions of particle clogging from experiments were satisfactorily reproduced in the simulation. Although the discharge rate increased with increasing initial loading, the discharge rate saturated at over M = 30 kg owing to the so called Janssen’s effect. The discharge corresponding to the change in particle shape and initial loading was in good agreement between the simulation and experimental results. The comparison of 2D/3D simulation shows that the experiments and simulations successfully minimized the 3D effect.

Jamming probability of granular flow in 3D hopper with shallow columns: DEM simulations

We performed a numerical study of the jamming that stops the flow of granular material from a three-dimensional hopper discharging due to gravity. When the hopper outlet is not much larger than the particles, granular material clogs the hopper outlet due to the formation of an arch or dome. For a wide range of particle diameters, we obtained the size distribution of the “avalanche,” defined as the number of particles that fall before jamming. We repeated this process through a discrete element method model verified with a simple experiment. From these distributions, we determined the probability of the flow jamming before N particles pass through the hopper. As the ratio between the hopper outlet diameter and the particle diameter increases, the probability that an arch will block the outlet decreases. We show here that the probability of one particle passing through the hopper is not constant when there are not sufficient particles. Then, we propose a new model that can quantify changes in particle passing probability. Using this model, we derive the particle passing probability in a hopper with shallow columns and confirm that the probability of one particle passing through the hopper is closely related to the pressure acting on the bottom of the hopper.

Experimental investigation on flow properties of biomass and pulverized coal binary powder mixtures

Co-gasification of coal with biomass is a novel way to utilize biomass energy and is a new research focus in clean coal technology. A thorough knowledge of the flow properties of biomass and coal binary mixtures is critical for proper processing of feedstocks to solve annoying flow problems which frequently occur in the equipment. In this paper, the flow properties (angle of repose, packing properties, and gravity discharge rate) of different biomass materials and pulverized coal binary powder mixtures were analyzed experimentally with a powder comprehensive characteristic tester and a gravity discharge experimental facility. The effects of the mixture ratio on the flow properties of different binary powder mixtures were investigated. Results indicate that the effects of the mixture ratio on the angle of repose for mixtures with different biomass species are different. For different biomass species, the bulk densities and tapped densities of their mixtures with coal decrease with increased mixture ratio. In the range of 0 ∼ 50% biomass mass content, as the mixture ratio increases, the discharge rates of different mixtures first increase, then decrease. When the biomass mass content is larger than 50%, arching phenomenon can be observed near the hopper outlet. A modified prediction model was proposed for the discharge rates of mixtures, with an error range from −45% to +25%.

Study of Electromagnetic Effect Parameters Influence on Fluidity of Fine Nd-Fe-B Powder

The paper experimentally proves the efficiency of electromagnetic effect on stimulated fluidity of magneto-hard powders. Fine Nd-Fe-B powder doesn’t have natural fluidity. To make it flow through hopper outlet we effected on the powder by constant and alternating gradient magnetic fields. Induction lines of constant magnetic field were horizontal, and alternating field lines were vertical. In order to form stimulated powder fluidity, higher induction gradient was situated below the powder receiver chamber. We experimentally found optimal magnetic fields parameters that form steady magneto fluidized bed from Nd-Fe-B powder, with an average particle size 1 μm. The study results of influence of magneto fluidized bed electromagnetic parameters on Ne-Fe-B powder efflux speed through outlets with diameters 1 and 2 mm are presented. Gradient field topology and parameters of electromagnetic effect providing minimal efflux time of 1000 mg of powder are defined.

Quantifying productivity of a gravity dispenser

In processing lines for the manufacturing of concentrated feed for farm animals, there is often an issue of operations coordination of machines according to their performance. Particularly, when delivering feed components to the mixer, it is essential to consider the performance of the dispenser distributing each of them. The productivity of the dispenser has to be no higher than the productivity of the mixer. In given article we have provided an example of calculating the theoretical performance of a gravity dispenser in a truncated cone-shaped hopper with dampers in the lower part. Calculations let us conclude that the main element affecting the productivity of the dispenser is the radius of the hopper outlet, since it is included in the formula in the second degree.

Shape optimization of conical hoppers to increase mass discharging rate

Mass discharging rate (MDR) is a critical aspect of hopper’s performance in bulk solids handling. A shape optimization method is established in this study to increase the MDR of cohesionless granular materials from hoppers. This method is based on a continuum model of granular matter and the Eulerian Finite Element Method (FEM) which can efficiently simulate the discharging process and predict the MDR. In this work with the focus on conical hoppers, the widths of silo and hopper outlet as well as the vertical height of hopper are fixed. The meridian of the hopper, however, evolves from a straight line to some optimal curve, guided by a combined genetic algorithm (GA) and gradient descent method (GDM). Cubic spline function is employed to parametrize the hopper shape. The effectiveness of the shape optimization is examined by comparing the MDRs of the optimal hopper and conventional conical hopper, obtained by both FEM and discrete element method (DEM) respectively. It is shown that this shape optimization method can automatically search the optimal shape of the hopper in a given range of constraints, and increase the MDR substantially. In a typical hopper with an initial half angle of 45°, the MDR is increased by over 130% after the shape optimization. Notably, the optimal shape depends mainly on the geometrical factors, i.e. the allowed width and height for the hopper, whilst insensitive to the material properties, which favors its general use for different particles. Such curved hoppers are particularly useful for increasing the discharge rate of hoppers ranging from 30° to 50°, which, facilitated with advanced manufacturing technology, will find wide potential applications in bulk solids handling.

Design optimization of an aerated hopper for discharge of cohesive pulverized coal

In this paper, pulverized coal was discharged from an aerated hopper at various aeration conditions, i.e., different aeration rates and aeration heights. The discharge characteristics of pulverized coal were analyzed in order to obtain the optimal aeration condition. The result showed that both aeration rate and aeration height could affect the discharge of pulverized coal. Discharge regions were divided and related to the different powder states inside the hopper. The ideal arch above the hopper outlet was analyzed. Its height was obtained during gravity discharge and its dependency with aeration was discussed. Maximum discharge rates under idealized aeration conditions were predicted and compared well with the experimental data. From the general equation for powder discharge and on the basis of the bubble motion theory, a mathematical model was built to predict the aerated discharge rate. With this model, it is possible to discuss the motion mechanism of particles and bubbles inside the hopper and to relate the optimal aeration height to the optimal aeration rate under idealized aeration condition. A logical algorithm for optimization design of aerated hopper was further proposed, which would be able to provide some reference for the aerated hopper design.

Modification Design of Shredded Meat Machine Using 1.5 Hp Motor Driver

The high level of consumption of processed beef products is a promised business opportunity to be developed. The shift in people’s consumption patterns in consuming processed meat products from fresh meat into ready to eat processed products has encouraged some parties to develop technology in terms of processing beef. The way of making shredded meat is still conventional, using bare-hands, knives or forks to slice meat after cooked into a shredded part. Obviously, the process of making shredded meat is taking times, more power, and by pounding using forks is considered to be less safe for workers. The purpose of this study was to obtain a simpler beef machine for raw materials to make shredded meat using 1.5 horsepowers (hp) drive motor. Modified the design of construction by designing the casing cylinder, the hopper inlet and outlet, the tub and the table, developing a new machine that is able to be tested. 1 kg of beef so that the results of the measurement of the sound texture of the fiber consisted of 0.5 mm fiber thickness, 30mm length; 1mm fiber thickness, 35mm long and 1.5mm fiber thickness, 35mm long. The capacity of the results of beef steaming is 3.3 ounces/minute or 1kg per 3 minutes. Therefore, it can be concluded that the more the gap in the casing, the better the smoother the results could be.

Application of Taguchi Method for Optimization of Parameter in Improving Soybean Cracking Process on Dry Process of tempeh Production

Taguchi method is a Design of Experiment approach for parameter optimization of a process. The purpose of this study is to determine the optimum parameters and the most influential parameters in the process of soybean cracking in the dry process of tempeh production. In the process of cracking the dry soybeans found a defect of 14.5%. after applying the Taguchi method and obtaining the optimum parameters, the defect on the dry process of cracking the dry soybeans is reduced to 6.6%. Determination of parameters and levels, objective functions, orthogonal array, signal-to-noise ratio, and analysis of variance (ANOVA) will be done in this study to improve the performance of the soy-cracking process. In this study there are three parameters used in conducting experiments with Taguchi method, three parameters namely distance between stones, hopper outlet diameter, and sun-drying duration. The results of this study are: distance between stones with setting optimum 1mm and percentage contribution 13%; hopper outlet diameter with setting optimum 25mm and percentage contribution 85%; and sun-drying duration with drying optimum 1 day and percentage contribution 2%. the most influential parameter is the hopper outlet diameter in the soybean cracking process, as it determines the soybean discharge that goes into the cracking phase.