Dingena L. Schott

A Methodology to Predict Power Savings of Troughed Belt Conveyors by Speed Control

Conventional troughed belt conveyors often receive material flows that are smaller than their conveying capacity. DIN 22101 indicates that reducing the belt speed, and thereby maximizing belt load, always results in a reduction of the required mechanical and electrical drive power. Predictions of the speed control savings by DIN22101, however, are inaccurate. Therefore power consumption savings can be truly validated only by physical measurements. Several measurements were carried out for validation purposes. With information on speed control savings an evaluation can be made whether the capital expenditures required for speed control conversion are economically feasible. This article provides a methodology to predict these savings with the use of DIN 22101.

Calibrating the microscopic properties of quartz sand with coupled CFD-DEM framework

Purpose – The macroscopic properties of dried sand can be correctly modelled when the accurate determination of the microscopic properties is available. The microscopic properties between the particles such as the coefficients of rolling (µ r) and sliding (µ s), are numerically determined in two different ways: with and without considering the fluid effect. In an earlier study, the microscopic properties were determined by discrete element method (DEM) and without considering the air effect on the macroscopic properties such as the Angle of Repose. The purpose of this paper is to recalibrate the microscopic properties through a coupling between the DEM and computational fluid dynamics (CFD). Design/methodology/approach – The first step is dedicated to the calibration of the CFD-DEM model through modelling a single particle sedimentation within air, water, and silicon oil. The voidage and drag models, the grid size ratio (D/dx), the domain size ratio (W/D), and the optimum coupling interval between the CFD...

Tensile test simulation of high-carbon steel by discrete element method

Purpose – The tensile test is one of the fundamental experiments used to evaluate material properties. Simulating a tensile test can be a replacement of experiments to determine mechanical parameters of a continuous material. The paper aims to discuss these issues. Design/methodology/approach – This research uses a new approach to model a tensile test of a high-carbon steel on the basis of discrete element method (DEM). In this research, the tensile test specimen was created by using a DEM packing theory. The particle-particle bond model was used to establish the internal forces of the tensile test specimen. The particle-particle bond model was first tested by performing two-particle tensile test, then was adopted to simulate tensile tests of the high-carbon steel by using 3,678 particles. Findings – This research has successfully revealed the relationships between the DEM parameters and mechanical parameters by modelling a tensile test. The parametric study demonstrates that the particle physical radius,...

Dust Emission Modelling around a Stockpile by Using Computational Fluid Dynamics and Discrete Element Method

Dust emissions can have significant effects on the human health, environment and industry equipment. Understanding the dust generation process helps to select a suitable dust preventing approach and also is useful to evaluate the environmental impact of dust emission. To describe these processes, numerical methods such as Computational Fluid Dynamics (CFD) are widely used, however nowadays particle based methods like Discrete Element Method (DEM) allow researchers to model interaction between particles and fluid flow. In this study, air flow over a stockpile, dust emission, erosion and surface deformation of granular material in the form of stockpile are studied by using DEM and CFD as a coupled method. Two and three dimensional simulations are respectively developed for CFD and DEM methods to minimize CPU time. The standard ?-? turbulence model is used in a fully developed turbulent flow. The continuous gas phase and the discrete particle phase link to each other through gas-particle void fractions and momentum transfer. In addition to stockpile deformation, dust dispersion is studied and finally the accuracy of stockpile deformation results obtained by CFD-DEM modelling will be validated by the agreement with the existing experimental data.

Bionic design methodology for wear reduction of bulk solids handling equipment

ABSTRACT Large-scale handling of particulate solids can cause severe wear on bulk solids handling equipment surfaces. Wear reduces equipment life span and increases maintenance cost. Examples of traditional methods to reduce wear of bulk solids handling equipment include optimizing transport operations and utilizing resistant materials. To our knowledge, the so-called bionic design has not been utilized. Bionic design is the application of biological models, systems, or elements to modern engineering. Bionic design has promoted significant progress on the development of engineering products and systems. In order to use bionic design for wear reduction of bulk solids handling equipment surfaces, this paper introduces bionic design to bulk solids handling on the basis of analogies between biology and bulk solids handling. In addition, a bionic design methodology for the wear reduction of bulk solids handling equipment surfaces is formulated. Based on the bionic design methodology, two bionic models used for abrasive and erosive wear reduction of bulk solids handling equipment surfaces are proposed.

An improved zero vibration method and parameter sensitivity analysis for the swing control of bridge-type grab ship unloader

This paper presents an improved zero vibration method for the swing control of bridge-type grab ship unloader. With the method, the concepts of equivalent frequency and the equivalent damping ratio are proposed to cope with the changeable length of rope, and the optimal path planning is considered to avoid collision and improve efficiency. Numerical simulation results of a case study indicate that the maximum residual swing angle of the grab can be limited to a small range to ensure safety using the improved zero vibration method, whereas the traditional zero vibration method with average frequency and zero damping ratio gets poor results of swing control. After that, the sensitivities of the max residual swing angle to the changes of some main design parameters (damping coefficient, deviation of the center of gravity of the grab in rope direction, and time delay of the system) and operating parameters (position deviation of the trolley, initial length deviation of the rope, and initial swing angle) are analyzed. The results obtained display that the residual swing angle is sensitive to the deviation of grab’s center of gravity, the deviation of trolley’s position, and the initial swing angle under the same control parameters, but insensitive to the damping coefficient, the time delay of the system, and the initial length deviation of the rope. This can help to select the appropriate parameter values or adaptive range in an actual unloader.

Fuzzy Controlled Energy Saving Solution for Large-Scale Belt Conveying Systems

Belt conveyors generally run at designed nominal speed. When material loading rate is smaller than the nominal conveying capacity the belt is under the situation of being partially filled. It provides the potential of reducing energy consumption by means of adjusting the speed of the belt. For practical reasons discrete control is preferred to adjust the belt speed. This paper presents a fuzzy control method to improve the energy efficiency of large-scale belt conveying systems. Fuzzy logic is applied to represent the change of material loading rate. A fuzzy control algorithm is developed to optimize the adjustment of belt speed to avoid potential material spillage and material overload caused by the short-term material loading peaks. Energy savingsareestimated by computer simulation. Simulation model and outputare verified by practical measurement.

Sensitivity analysis of DEM prediction for sliding wear by single iron ore particle

Purpose Sliding wear is a common phenomenon in the iron ore handling industry. Large-scale handling of iron ore bulk-solids causes a high amount of volume loss from the surfaces of bulk-solids-handling equipment. Predicting the sliding wear volume from equipment surfaces is beneficial for efficient maintenance of worn equipment. Recently, the discrete element method (DEM) simulations have been utilised to predict the wear by bulk-solids. However, the sensitivity of wear prediction subjected to DEM parameters has not been systemically investigated at single particle level. To ensure the wear predictions by DEM are accurate and stable, this study aims to conduct the sensitivity analysis at the single particle level. Design/methodology/approach In this research, pin-on-disc wear tests are modelled to predict the sliding wear by individual iron ore particles. The Hertz–Mindlin (no slip) contact model is implemented to simulate interactions between particle (pin) and geometry (disc). To quantify the wear from geometry surface, a sliding wear equation derived from Archard’s wear model is adopted in the DEM simulations. The accuracy of the pin-on-disc wear test simulation is assessed by comparing the predicted wear volume with that of the theoretical calculation. The stability is evaluated by repetitive tests of a reference case. At the steady-state wear, the sensitivity analysis is done by predicting sliding wear volumes using the parameter values determined by iron ore-handling conditions. This research is carried out using the software EDEM® 2.7.1. Findings Numerical errors occur when a particle passes a joint side of geometry meshes. However, this influence is negligible compared to total wear volume of a wear revolution. A reference case study demonstrates that accurate and stable results of sliding wear volume can be achieved. For the sliding wear at steady state, increasing particle density or radius causes more wear, whereas, by contrast, particle Poisson’s ratio, particle shear modulus, geometry mesh size, rotating speed, coefficient of restitution and time step have no impact on wear volume. As expected, increasing indentation force results in a proportional increase. For maintaining wear characteristic and reducing simulation time, the geometry mesh size is recommended. To further reduce simulation time, it is inappropriate using lower particle shear modulus. However, the maximum time step can be increased to 187% TR without compromising simulation accuracy. Research limitations/implications The applied coefficient of sliding wear is determined based on theoretical and experimental studies of a spherical head of iron ore particle. To predict realistic volume loss in the iron ore-handling industry, this coefficient should be experimentally determined by taking into account the non-spherical shapes of iron ore particles. Practical implications The effects of DEM parameters on sliding wear are revealed, enabling the selections of adequate values to predict sliding wear in the iron ore-handling industry. Originality/value The accuracy and stability to predict sliding wear by using EDEM® 2.7.1 are verified. Besides, this research accelerates the calibration of sliding wear prediction by DEM.

Large-scale homogenization in mammoth silos: calculating homogenization efficiency and modeling input properties

Abstract The homogenization theory of mammoth silos is investigated in order to establish the homogenization efficiency of mammoth silos. These silos, where homogenization is achieved by intersecting multiple layers during reclaiming of the silo, e.g., by inclining the screw conveyor, can be used for large-scale homogenization of both cohesive and free-flowing materials and are therefore an alternative for blending piles. The presented homogenization model and the calculation of the homogenization efficiency in mammoth silos depend on two variables: the volume distribution and the input properties of the bulk material to be homogenized. The silo geometry and the chosen stacking and reclaiming method determine the first variable. The second variable, time series representing the input properties of a material flow, depends on the material to be homogenized. This paper focuses on modeling input properties and shows that higher order ARMA(p,q) models are required for describing these input properties, instead of the frequently assumed AR(1) models in literature. It does not concentrate on the comparison of predicted and simulated output variances. Conducted simulations of the homogenization efficiency with both ARMA and AR(1) models are found to be very encouraging because the standard deviation of the output properties is reduced on average by a factor 5, i.e., the standard deviation of the output properties is reduced to 20% of the standard deviation of the input properties.

Numerical calculations of environmental impacts for deep sea mining activities

With the expected dramatic increase of mineral resources consumption, deep sea mining (DSM) was proposed as a method supplying the running of world economy by cooperating with or compensating for the terrestrial mining industry. However, its industrialization process is hindered by various reasons including the technological feasibility, economic profitability, and the DSM environmental impacts. The objective of this paper is to calculate the DSM environmental impacts based on a DSM environmental impact framework, which was selected through a systematic literature review in earlier work. The numerical calculations focus on the initial DSM disturbances and plume source, species disturbance, sediment plume and tailings. More importantly, the interconnection between the sediment plume and the species disturbances is also analysed particularly in this paper. The research quantifies the environmental impacts into a systematic framework, which could be helpful to assess the comprehensive environmental performances of a DSM activity and to promote the DSM industrialization process in the future.