Granulation Chamber Research Articles

ИССЛЕДОВАНИЕ УСЛОВИЙ ДВИЖЕНИЯ МАТЕРИАЛА В КАМЕРЕ ГРАНУЛИРОВАНИЯ

The article substantiates the need for scientific and technical developments, theoretical and experimental studies of the processes of agglomeration of powdery, viscous-plastic materials, as well as materials of an anisotropic structure to obtain molded bodies of a given granulometry in order to improve their consumer properties. A mathematical model is presented. It describes the conditions of material movement in the granulation chamber, which is presented as a system of differential equations for the movement of a viscous incompressible fluid in a cylindrical coordinate system. The results of the theoretical studies carried out are confirmed by physical modeling of the technological process of granulation. According to the study of the conditions of movement of the material in the granulation chamber, it is conclude that the rate of shear deformations of the material layer across the width of the chamber varies unevenly, that is, the degree of freedom of the particles in it is limited. A solution is proposed to eliminate this disadvantage by creating more favorable conditions for the implementation of granulation processes, which can be created in a toroidal or close to it in shape chamber due to the intensification of the volumetric and spatial movement of the material.

Parallel compensator for zero dynamics stabilization in fluidized bed spray granulation

This contribution is concerned with the stabilization of continuous fluidized bed spray granulation processes with external sieve mill cycle. To keep the overall mass of particles inside the granulation chamber in well-defined bounds these processes are in general operated with a mass controller. This configuration is well-known to become unstable for certain ranges of the milling diameter. Here, the instability results in a nonlinear limit cycle of the particle size distribution. As has been shown in a previous contribution the stability problem is not inherent to the process, which is open-loop stable over a wide range of operating conditions. In fact, the root cause for the instability is the mass controller, which interacts with the unstable zero dynamics of the granulation process. To overcome this problem a parallel compensator will be designed, which allows to stabilize the process zero dynamics and thus solves the problem of control induced instabilities.

МАТЕМАТИЧЕСКОЕ МОДЕЛИРОВАНИЕ И УПРАВЛЕНИЕ ДВИЖЕНИЕМ ОДИНОЧНОЙ КАПЛИ ДОМЕННОГО ШЛАКА В ПОТОКЕ ГАЗА ПРИ СУХОЙ ГРАНУЛЯЦИИ

Dry granulation plants of blast furnace slag allow obtaining granulated slag and use heat of liquid slag. When introducing dry granulation of slag, emissions of harmful sulfur compounds into the atmosphere are excluded. When designing the granulation chamber, it is necessary to evaluate the main size of the chamber - its diameter to avoid slag sticking to the walls of the chamber. The slag droplets must solidify before colliding with the wall. In this work, the authors developed a mathematical model for the movement of a single droplet of molten blast furnace slag during dry granulation, which allows controlling the cooling process of a single droplet of molten blast furnace slag in the granulation chamber.

Effect of processing conditions and material attributes on the design space of lysozyme pellets prepared by extrusion/spheronization

The present work aimed to investigate the impact of the critical material attributes on the design space of the production of lysozyme pellets with suitable biological and physical properties for the subsequent coating process. The effect of two brands of both lysozyme and conformation stabilizing mannitol on the behavior of the composition in an extrusion/spheronization process was studied, while the experiments were designed according to 23 factorial design. The kneading of the mass was carried out in a high shear granulator equipped with a specially designed granulation chamber (Opulus Ltd, Hungary) constructed with seven built-in sensors for the measurement of temperature and relative humidity (RH). The special chamber is a novel tool for the identification of the critical points during processing a thermolabile drug by providing the online monitoring of critical environmental parameters and could be used to accurately determine the effect of critical process parameters and material attributes. The prepared samples were investigated for their biological and physical properties. It was found that the critical material attributes have a potential effect on the production process and product quality, and highly influence the size of the process design space. Therefore, the screening of the formulation materials is a key factor in macromolecular drug development.

Effect of geometric parameters at open turbine combined structure on flow field distribution of dry granulation for Si3N4 powder

To improve the uniformity of the flow field and the poor axial velocity in the chamber of Si3N4 dry granulation, the influence of geometric parameters at open turbine combined structure on the flow field distribution is studied. The Euler–Euler gas-solid two-phase flow model is established and the physical model of dry granulation chamber under the combined structure is simplified. Under the same radial structure, the volume distribution and velocity field of Si3N4 particles in the granulation chamber with a different number and angle of the axial structure at the open turbine are analyzed by the CFD method. The influence of the axial structure at the open turbine on the flow field distribution of Si3N4 particles under different geometric parameters is compared. The results show that the axial structure of the open turbine in the granulation chamber is the most uniform when the number of blades is 6 and the inclination angle is [Formula: see text], and the circulating flow of the upper and lower parts of Si3N4 powder is strong.

Control induced instabilities in fluidized bed spray granulation

This contribution is concerned with the stability problems occurring during the operation of continuous fluidized bed spray granulation processes with external sieve mill cycle. These processes are in general operated by a mass controller, which guarantees that the overall mass of particles in the granulation chamber stays in well-defined bounds. It is well-known that, depending on the milling diameter, instabilities may occur, which result in a nonlinear limit cycle of the particle size distribution. To overcome this problem two approaches have been proposed in the literature, constrain the admissible parameter space to exclude regions of instability and design additional stabilizing control loops. In the present contribution, the cause of this instability phenomenon will be studied. It will be shown that the instability is not inherent to the process, which turns out to be open-loop stable over the studied parameter range, but due to the mass controller. More specifically, it will be demonstrated that the zero dynamics of the granulation process become unstable for certain parameter ranges resulting in closed-loop unstable process behavior. To point out, that this behavior does not depend on the specific mass controller design procedure, three prototypical mass controllers of practical relevance are designed and analyzed.

Film fragmentation mode: The most suitable way for centrifugal granulation of large flow rate molten blast slag towards high-efficiency waste heat recovery for industrialization

In molten slag centrifugal granulation heat recovery technology, the centrifugal granulation process is crucially important to realize efficient heat recovery as well as high-quality resource utilization. Facing the actual large-scale industrial application, the film fragmentation mode is likely to be the suitable operational mode for centrifugal granulation due to its ability to handle large discharged slag flow. However, the fragmentation phenomena and mechanism in film fragmentation mode are unclear since most of the existing experiments scale is too small to reach this mode. Here, the authentic molten slag is employed as the working fluid to investigate the centrifugal granulation characteristics in film fragmentation mode. A unique perforated disintegration of extended free slag sheet in film fragmentation mode is observed, and the good granulation performance is proved through the comparison with that in ligament fragmentation mode. The effects of operating conditions and structural parameters including granulator rotating speed, molten slag mass flow rate, initial slag temperature, rotary cup diameter, and granulation chamber radius are discussed on the particle size distribution and average particle diameter. Finally, the predictive correlation of granulation performance is put forward. For the industrial applications, the rotary cup diameter is recommended between 86 mm and 126 mm, and the granulation chamber radius should be set at least larger than 1.36 m if the granulator rotating speed is designed lower than 1800 rpm.

Heat Transfer in Fluidized Beds in a Dry Slag Granulation Unit

The world’s leading countries develop dry slag granulation units that are capable of producing solid slag granules and recovering the sensible heat of slag. The main element of such units is a granulation chamber where molten slag is atomized and solidified. In this chamber, up to 30% of the sensible heat of the molten slag is extracted. To recover more heat, the solid granules from the granulation chamber should be fed to fluidized beds. The more there are such beds, the better the granulated slag can be cooled and, therefore, the more heat can be recovered. Foreign publications on dry slag granulation do not provide methods for designing fluidized beds for dry slag granulation units. A method for analyzing the heat transfer in fluidized beds during cooling of slag granules by counter airflow is presented. The method allows determining the heat flow from the slag to the air in fluidized beds and the temperatures of the slag and air exiting the fluidized beds. Recommendations on choosing the airflow velocity, the rational mass of slag in one fluidized bed, the number and dimensions of beds and evaluating air pressure losses in fluidized beds are formulated. It is shown that three fluidized beds in a dry slag granulation unit are sufficient to recover up to 92% of the sensible heat of slag.

Analysis of flow field in Si3N4 dry granulation chamber with non-standard composite structure

In order to improve the whirling phenomenon of Si3N4 particles in the granulation chamber, the influence of the structure of the granulation chamber on the internal distribution is explored. Euler Euler’s two-phase flow model is established. The flow field in the combined structure granulation chamber with different layout is simulated. The volume distribution and velocity field change of Si3N4 particles in the combined structure granulation chamber with different layout are analyzed. The results show that the angle between two adjacent composite structures is 20∘, 60∘, 80∘ and completely standard the Si3N4 particles with volume fraction index greater than 0.8 account for 10.2%, 11.5%, 12.5% and 6.7% of the total volume respectively. When the combined structure is completely standard, several small convolutions are found. The whirling phenomenon in the granulation chamber is improved. When the angle between two adjacent composite structures is 20∘, 60∘, 80∘ and complete standard, the proportion of qualified particles is 59%, 64%, 66% and 68%. The fluidity index is 84, 85, 87 and 88, respectively. To sum up, the combination structure of the granulation chamber is a complete standard, it is beneficial to improve the spin phenomenon of Si3N4 particles in the granulation chamber.

Heat Exchange in the Granulation Chamber of an Installation for Slag Dry Granulation

In the blast-furnace production, fiery-liquid slags have temperatures of about 1400–1500 °C at the exit from the furnace. For the utilization of their sensible heat, the world leading countries develop special installations for slag dry granulation aimed at getting dry granulated slags and using the heat of liquid slags for the purposes of heating of air or another gas. In addition, the introduction of the process of slag dry granulation instead of the wet granulation of slag applied at present excludes the possibility of ejection of harmful sulfur compounds and does not require additional heat consumption spent for drying wet granulated slags. In the available methods aimed at the dry granulation of slags, it is proposed to use the air heated to a temperature of 500–600 °C in a boiler (utilizer) intended for the generation of steam, which is then either delivered to a turbine generating electric energy or directly used for the industrial purposes. We propose a method for the numerical analysis of heat exchange in the process of cooling of blast-furnace slag in the granulation chamber of the installation for dry granulation. By using this method, one can determine the optimal main size of the granulation chamber, i.e., its radius.

On the dynamics and control of continuous fluidized bed layering granulation with screen-mill-cycle

This paper is concerned with an experimental and theoretical study of dynamics and control of fluidized bed layering granulation with external screen mill cycle. To achieve quantitative agreement between model calculations and experiments an extended dynamic process model is proposed. In contrast to previous work by Dreyschultze et al. [1] specific plant characteristics are taken explicitly into account including a more detailed model of the milling process and a classifying particle withdrawal from the granulation chamber. The model is then used to develop new control strategies. First, a novel bed mass controller is designed and validated. Afterward, a second control loop is introduced to dampen the oscillatory behavior of the particle size distribution. It is shown that the new control concepts achieve stable steady-state operation within a short time and thereby improve the process dynamics significantly. Theoretical predictions and experimental results are shown to be in good agreement.

Numerical analysis of temperature field in the high speed rotary dry-milling process

For the effect of the temperature field in the ceramic dry granulation. Based on the Euler-Euler mathematical model, at the same time, made ceramic dry granulation experiment equipment more simplify and established physical model, the temperature of the dry granulation process was simulated with the granulation time. The relationship between the granulation temperature and granulation effect in dry granulation process was analyzed, at the same time, the correctness of numerical simulation was verified by measuring the fluidity index of ceramic bodies. Numerical simulation and experimental results showed that when granulation time was 4min, 5min, 6min, maximum temperature inside the granulation chamber was: 70°C, 85°C, 95°C. And the equilibrium of the temperature in the granulation chamber was weakened, the fluidity index of the billet particles was: 56.4. 89.7. 81.6. Results of the research showed that when granulation time was 5min, the granulation effect was best. When the granulation chamber temperature was more than 85°C, the fluidity index and the effective particles quantity of the billet particles were reduced.

The Selection of Ceramic Dry Granulating Machine Spray Device Based on the DPM Model

In order to improve the dispersity of true particles in the process of ceramic dry granulation, by adding a sprayer in the upper of granulation chamber to make water spray into droplets, which greatly increases the contact area of liquid water and powder. The atomization flow field of plain-orifice-nozzle, pressure-swirl-nozzle, air-blast-nozzle, effervescent-nozzle with 1mm nozzle diameter is simulated based on the DPM model, obtaining the droplet size distribution cloud picture and atomization flow field simulative cloud picture of four kinds of nozzle. The simulation results show that the average droplet size of pressure-swirl-nozzle is the minimum and the disperisity of atomization flow field of air-blast-nozzle, effervescent-nozzle, pressure-swirl-nozzle, plain-orifice-nozzle increases in turn. In terms of the average droplet size and the dispersity of atomization flow field, the droplet dispersity of pressure-swirl-nozzle is better and the average droplet size is the minimum, which is most beneficial to solve the problem of fully dispersity of really particle. Therefore, pressure-swirl-nozzle is best fit for the spray device of ceramic dry granulation.

Analysis of Temperature Field on Ceramic Dry Granulation Machine

In the paper, we establish a 3D mathematical model of granulation chamber based on experimental data and “two phase flow” theory, simulate the process of dry granulation and study the temperature field of granulation chamber. The analysis result shows that granulation time must be controlled in 6 minutes, otherwise the plasticity of particles will be damaged and the final effect of granulation will be influenced.

Labscale fluidized bed granulator instrumented with non-invasive process monitoring devices

Fluidized bed granulation is a common size enlargement process in the pharmaceutical industry, in which fine powder is agglomerated using a liquid binder to obtain larger granules. However, fluidized bed granulation is a complex process by nature, being difficult to control due to the strong interactions between many process variables, such as moisture content and granule size. In order to control the process via correct pathway, one should be able to monitor the process, i.e. measure the process variables in-line. In this study, three Process Analytical Technology (PAT) devices, i.e. an acoustic emission sensor, a flash topography particle size analyzer and multi-point NIR probes, were developed and instrumented into a labscale fluidized bed granulator for simultaneous granulation process monitoring. Parallel techniques were used for characterizing the granule size distribution and moisture content of granules during fluidization. Cellets R, protease granules and caffeine formulation were used as samples. Granulation was carried out in a custom made modular top spray granulation chamber. The granule size values obtained with the acoustic emission and flash topography particle size analyzer were in good agreement with the values measured with offline reference methods. Multi-point NIR (eight probes) and acoustic emission methods were able to detect the three granulation phases, mixing, agglomeration and drying. Single location monitoring does not reflect the heterogeneous sample during granulation, and thus, more information can be obtained by multi-point NIR. In general, the sensitivity of the multi-point NIR technique is susceptible to the fouling of probe windows whereas the acoustic emission technique is sensitive to background fluidizing air flows as well as external interference. The most informative data can be obtained when multiple PAT techniques are applied simultaneously for in-line process monitoring.