Manufacturing of Vortex Granulators: Simulation of the Vortex Fluidized Bed Functioning under the Disperse Phase Interaction in the Constrained Motion

The work presents the computer simulation results describing the motion of the interacting particles in a vortex fluidized bed (the constrained motion). The data obtained reveal the peculiar features of the poly disperse system motion in the apparatuses with the variable cross-section of the workspace. The empirical coefficient determining the residence time of a particle in the vortex fluidizer bed was calculated. An algorithm of the residence time calculations for a particle in the vortex fluidized bed under the constrained motion is developed. The results of com-puter simulation were a part of engineering (technological and constructive) algorithm of calculation for the future manufacturing of granulator’s industrial sample

Vortex-Type Granulation Machines: Technological Basis of Calculation and Implementation Roadmap

This work is devoted to describing the technological foundations and the main stages of calculating granulation machines with active hydrodynamic modes. The optimisation criterion is substantiated when choosing the design of the granulation machine. The work uses methods of analysis and synthesis, search for cause-and-effect relationships, theoretical and computer modelling, and experimental studies. The nodes of the vortex granulator directly influence the formation of a vortex fluidised bed, and the directional movement of granules of various sizes are determined. A technique for carrying out a computer simulation of the hydrodynamic operating conditions of a granulation machine in various operating modes with an assessment of the qualityof granulated products (e.g., the production of porous ammonium nitrate) is proposed. The results of a computer simulation of the process of formation of a vortex fluid-ised bed are presented. A variant of the solution for developing an automation scheme for a vortex-type granulation machine is shown. A roadmap for introducing granulation technology in vortex-type granulation machines is described with details of the main stages. The prospects for improving the design of a vortex-type granulation machine and optimising the operation of a granulation plant to produce porous ammonium nitrate are outlined

Fracture Analysis of High-Strength Screw for Highway Construction

High-strength screws represent one of the main joining or fastening components which are commonly used in the process of installation of frame constructions for information boards or signposts, relating to the traffic roads. The control of the production process may not always be a sufficient method for ensuring road safety. The backward investigation and control of the screw material processing seems to be the one of the most important procedures when there is the occurrence of any failure during the operation of the screw. This paper is mainly focused on the analysis of the failure of the high-strength screw of 10.9 grade with M diameter of 27 × 3 and a shank length of 64 mm. The mentioned and investigated screw was used as a fastener in a highway frame construction. In the paper, there is mainly the analysis of the material for a broken screw in terms of the material micropurity, the material microstructure, the surface treatment as well as chemical composition. The evaluation was based on investigation by optical microscopy, scanning electron microscopy and energy dispersive spectroscopy. Important knowledge and results were also obtained due to information on micromorphology and material contrast of the fracture surface resulting from fractographic analysis, using the method of scanning electron microscopy. In the case of the production of the high-strength screws, the tempering stands for the decisive or crucial process of heat treatment because the given process can ensure a decrease in hardness, while the required ductile properties of the material are kept and this is also reflected in the increase of strength and micromorphology of the fracture surface. From the aspect of micropurity, inclusions of critical size or distribution were not identified in the material, referring to Czech standard ČSN ISO 4967 (420471). The microstructure corresponds to tempered martensite, but the fracture surface of the broken screw was based on an intercrystalline micromechanism, which is undesirable for the given type of component. Combined with the measurement of the HV1 (Vickers hardness at a load of 1 kg) from the edge to the central area of the screw, the analysis revealed the significant drawbacks in the heat treatment of the high-strength screw

Investigation of the Convection Drying Process in a Multistage Apparatus with a Differential Thermal Regime

This paper describes a search for an optimal organization of the drying agent motion in the convection dryers. An overview of the main methods on how to reduce the energy consumption for the convection drying of the disperse materials is presented. The use of the multistage shelf apparatuses with a differential thermal regime for the con-vection drying of the disperse materials is justified. The work contains the results of a computer modeling on de-termining the drying temperature and moisture characteristics with the use of various methods of the organization of the drying agent motion. The model is realized implementing the author?s software product Multistage Fluidiz-er?. The software product enables to automatize calculation simultaneously by several optimization criteria and to visualize calculation results in the form of 3D images. The engineering computation of sectioning devices meth-odology with fluidized bed of particles is based on the calculation results. The automated calculations results give a base to design industrial drying device with a differential thermal regime

Complex designing of granulation units with application of computer and software modeling: case “Vortex granulator”

The article is devoted to the description of the complex method to design granulation unit, which is based on the joint use of the computer modeling results on the simulation models and software modeling based on author’s software products. The description of the software package Granulation Unit© to carrying out the structural and technological calculations for the granulation unit is given. The role of computer and software modeling in the general design algorithm of the granulation unit is shown. The optimization criteria are selected and an algorithm of design optimization for granulation unit is described using the example of the "Vortex Granulator" case. A general method of granulation unit designing "turnkey" with the use of automated design elements is presented. The results of automated calculations form the base to design an industrial granulation unit for the porous ammonium nitrate production. On the example of a specific product of the granulation unit (porous ammonium nitrate), the author's software product is presented to determine the quality of the porous surface in the granule. This approach in modeling allows to create the automated systems for the optimization calculation of granulation equipment

Granulation machines with highly turbulized flows: creation of software complex for technological design

The article deals with author’s software products review to calculate devices with highly turbulized flows as a part of granulation units. Principal scheme and model of the granulation unit, algorithm of the granulation technical calculation are represented in the work. The complex automated calculation technique of the granulation units is proposed. The proprietary software for calculation of main stages in the granulation process is observed in the research. Short description and functions of main software products to implement basic algorithm are given: Vortex Flow©, Conical Channel©, Conical Granulator©, Multistage Heat Treatment©, Vortex Tray©. As a result of the optimization calculation, the user of programs will get the following information: optimal construction of the vortex granulator’s workspace, necessary number of stages in the multistage shelf drier for granules’ final drying, number and construction of the vortex tray with heat and mass transfer separation elements for exhaust gases cleaning. All software products enable to export the received data and to exchange these data between each other. The complex algorithm and software products, proposed in the article, let to carry out optimization calculation of the main technological equipment in the granulation unit at its designing stage without expensive multifactorial experiment. The presented granulation units’ calculation algorithm and software products for its realization enable to carry out equipment changeover if raw material characteristics and the productivity of the unit are changed. The automated calculations results give a base to design industrial granulation unit for porous ammonium nitrate production

Fluidized bed in gravitational shelf dryers: optimization calculation

The article deals with studying the hydrodynamic characteristics of the fluidized bed in gravitation shelf dryers. The algorithm to calculate hydrodynamic characteristics of the fluidized bed in the dryer’s workspace is described. Every block of the algorithm has a primary hydrodynamic characteristics theoretical model of calculation. Principles of disperse phase motion in various areas in the gravitation shelf dryer are established. The software realization of the author’s mathematic model to calculate disperse phase motion trajectory in a free and constrained regime, disperse phase residence time in the dryers’ workspace, polydisperse systems classification is proposed in the study. Calculations of disperse phase motion hydrodynamic characteristics using the software product ANSYS CFX, based on the author’s mathematic model, are presented in the article. The software product enables automating calculation simultaneously by several optimization criteria and visualizing calculation results in the form of 3D images. The disperse phase flow velocity fields are obtained; principles of a wide fraction of the disperse phase distribution in the workspace of the shelf dryer are fixed. The way to define disperse phase residence time91 in the workspace of the shelf dryer in free (without consideration of cooperation with other particles and dryer’s elements) and con-strained motion regimes is proposed in the research. The calculation results make a base for the optimal choice of the gravitation shelf dryer working chamber sizes

Technology for porous ammonium nitrate production: modeling of drying machines’ operating modes

The article deals with the technological principles regarding the final drying process of porous ammonium nitrate (PAN) granules in multistage gravitational shelf dryers. The data on the dryers’ optimal technological operating modes are obtained. PAN samples are studied; the regularity of porous structure change in the granule, depending on the dryers’ hydrodynamic and thermodynamic conditions, is also established. Experimental data obtained during the research will be used to create a methodology for the engineering calculation of gravitational shelf dryers. Moreover, the data on the optimal operating conditions of drying machines at the final drying stage will be used to improve the technology to form porous granules from agricultural ammonium nitrate

Determining the main regularities in the process of mineral fertilizer granule encapsulation in the fluidized bed apparatus

This paper has substantiated the expediency and prospects of obtaining organomineral fertilizers by encapsulating mineral granules with an organic suspension in fluidized bed apparatuses. An overview of existing approaches to the mathematical description of the kinetics of granule growth in granulation processes in fluidized bed apparatuses is presented. A mathematical model of the kinetics of the formation of a hard shell around granules in a fluidized bed has been built. It shows that the kinetics depend on the size of the retour particles, the specific flow rate of the suspension, the density of the suspension and granules, and the time of the process. Equations have been derived for determining the thickness of the hard shell and the specific flow rate of the suspension for individual granulation stages in a multi-stage granulator of the fluidized layer. Analytically, graphical dependences were built, which showed an increase in the thickness of the hard shell due to an increase in the specific flow rate of the suspension, the diameter of the retour particles, and the time of the encapsulation process. The equations make it possible to determine the rational regime and technological parameters of the encapsulation process in order to obtain a coating of the predefined thickness at the surface of the granules. This ensures that a quality product is obtained, with a granulometric composition in a narrower range of particle size. To obtain granules of 2.5–4 mm in size, it is necessary to carry out the process in three- or four-stage granulators of the fluidized bed at specific suspension consumption of (10–20)∙10-4 kg/(kg∙s.). It is shown that with uniform growing of granules with a constant increase in the thickness of the shell in multistage granulators, the suspension consumption decreases by 2‒3 times from the first stage to the subsequent ones. This approach reduces the operating and energy costs of the process

Calculation of the Characteristics of the Multi-gap Seal of the Centrifugal Pump, in Dependence on the Chambers’ Sizes

The paper presents the results of an experimental research and a numerical calculation of a multi-gap seal of a centrifugal pump. The experimental research allowed to obtain the characteristics’ performance of the multi-gap seal at different operating modes, in dependence on the axial size of the chambers, pressure distributions’ changes, and a leakage from the seal. Using finite volume methods, values of radial hydrostatic forces, pressure distributions and leakage values were obtained. The results of the numerical calculation were compared with the results of the experiment, which showed that they matched