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This article focuses on the experimental verification of a mathematical derivation of Janssen’s theory, which describes the distribution of pressures within the bulk material and pressure distribution on the walls of storage facilities. The experimental verification is performed in two ways. The first is the real measurement of the load transfer in a bulk material cylinder and the second is similar to the detection of the load transfer through simulations using the DEM method. The aim is to compare the results of the theoretical calculation according to Janssen’s theory with the real measurement and a simulation of exactly the same model situation. At the beginning of any design or optimisation of existing transport or storage facilities, the most important is the analysis of the bulk material in the form of measurements of mechanical-physical properties. The analysis methods used are also described here. The pressure at the bottom of a storage container between the methods used showed negligible differences. From this finding, it can be concluded that the DEM method is a very suitable means for verifying the design of transport and storage facilities. The simulations provide important information and insights that can also be used to optimise existing transport or storage facilities.

This article focuses on the monitoring of air tunnels in sand, which in common practice are characterised as flow disturbances in the flow of bulk materials inside storage devices, hoppers, silos etc. In this case air tunnels are monitored by the ECT (Electrical Capacitance Tomography) method. The basic principle of the ECT tomographic method is the measurement of permittivity of a measured non-conducting medium. The results gained by an ECT device are then compared with the real, precisely defined measured state. The measured results show that the monitoring of flow disturbances in storage devices using ECT is a new method which does not use optical methods during measurement.

Currently, emphasis is placed on the efficiency of process technology in the production of energy. Large energy corporations are forced to develop new and optimize existing technologies to reduce emission limits. In coal and biomass combustion technologies, it is important to continually monitor and evaluate the quality of input material. A sampling device is used to obtain a representative sample of the fuel from the continuous conveying process. In this research work, the effect of setting the operating conditions of the rotating sampling device for coal, which is intended for combustion is investigated. From the operating tests, it was found that the different settings of the sampling device (velocity, dimensional parameters) influence the quality and quantity of a representative sample of coal taken from the belt conveyor of the technological line. [ABSTRACT FROM AUTHOR]

Results obtained from measuring the required amount of steel abrasive material with various fragmentations, which is transported by a special kind of scraper conveyor, offers information that is useful for operators of the abrasive blast cabinets. The presented article describes an innovative methodology developed for determination of the most relevant operational parameters relating to the above-mentioned situation. The most important parameters in this case are: the optimal amount of the abrasive material, the conveying speed of the scraper conveyor and the feeding of the conveyor with regard to partial or full elimination of instable operational area. Elimination of the instable operational area is possible by means of a simple constructional modification of the given conveying system according to the results obtained from experimental investigation, which was performed using special, originally developed laboratory testing equipment. [ABSTRACT FROM AUTHOR]

Copyright of Waste Forum is the property of Czech Environment Management Center (CEMC) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Inzynieria Mineralna is the property of Polskie Towarzystwo Przerobki Kopalin and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Inzynieria Mineralna is the property of Polskie Towarzystwo Przerobki Kopalin and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Waste Forum is the property of Czech Environment Management Center (CEMC) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Inzynieria Mineralna is the property of Polskie Towarzystwo Przerobki Kopalin and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper's goal was to select methods and a calibration procedure which would lead to the determination of relevant parameters of a discrete element method (DEM) and virtual material creation. Seven particulates were selected with respect to their shape (spherical and non-spherical), size and density. The first calibration experiment involved "packing test" to determine the shape accuracy and bulk density of virtual packed particulates. The series of simulations were compared with real experiments, and the size, shape and density of virtual particles were optimized. Using three apparatuses, the input parameter values were experimentally determined for a contact model that defines the behavior of particulates in DEM simulations. The research part of the paper examines the influence of factors such as particle number; pile formation method; and the method of evaluation of the angle of repose on the process of the calibration of virtual material. The most reproducible results were achieved by the "pilling" method and by the rotating drum—both evaluated by the geometric method. However, it is always advisable to make an overall visual comparison of the slope shape between the calibration simulation and the experimental curves. The bowl's diameter to particle size ratio should be greater than 25, and the calibration experiment should contain approximately 4000 particles to ensure representative results during angle of repose calibration experiment. [ABSTRACT FROM AUTHOR]

The process of homogenization of particulates is an indispensable part of many industrial processes, and, therefore, it is necessary to pay a special attention to this area and develop it. This paper deals with a complex study of homogenization of particulate matters in a rotary drum in terms of shape, size, and density of particles. In addition, the influence of operating parameters, such as drum filling capacity, rotational speed, and drum filling pattern are also investigated. Studies of reproducibility of discrete element method simulations, effects of rotary drum sizes or effects of drum volumetric filling to the mixture homogeneity index were also carried out. In general, the least satisfactory values of the homogeneity index resulted from the mixing of particles with different densities. The dominating factor of homogenization was the drum filling-up degree. The course of the homogeneity index in 140, 280, and 420 mm drums was very similar and after five revolutions of the drum, identical values of the homogeneity index were achieved for all the drum diameters. The optimal drum filling-up degree is at 40–50% for the spherical particles and 30–40% for the sharp-edged particles. The repeatability of simulations showed the maximum relative standard deviation of the homogeneity index at 0.6% from ten simulation repetitions with the same parametric conditions. [ABSTRACT FROM AUTHOR]

This experimental study focusses on the viability of three low-grade biofuels in small-scale biomass units of 7–12 kW The tested materials were homemade grass pellets (gp1 and gp2) and a mixture of leaves and woody pellets (lp50) that were made without binders and completely characterized in terms of their chemical and physical properties (proximate analysis, elementary composition, ash content, flowability, etc.). The results obtained with the non-commercial fuels were compared with commercial wood pellets (wp). The viability study comprised the operational parameter influences, such as primary and secondary airflow, fuel consumption, etc., together with the impact of those parameters on the main problems in combustion (concentration and particle distribution, fouling and slagging). The results revealed that the biomass whose behavior during combustion induced fewer particulate emissions and deposits was the mixed fuel, made of 50% leaf + 50% wood pellet (lp50). Contrary to the grass-based pellets, lp50 has the possibility of being used in commercial devices with the incorporation of processes during the manufacturing that improve their properties. [ABSTRACT FROM AUTHOR]

There is hardly any industry that does not use transport, storage, and processing of particulate solids in its production process. In the past, all device designs were based on empirical relationships or the designer’s experience. In the field of particulate solids, however, the discrete element method (DEM) has been increasingly used in recent years. This study shows how this simulation tool can be used in practice. More specifically, in dealing with operating problems with a rotary cooler which ensures the transport and cooling of the hot fly ash generated by combustion in fluidized bed boilers. For the given operating conditions, an analysis of the current cooling design was carried out, consisting of a non-standard intake pipeline, which divides and supplies the material to two rotary coolers. The study revealed shortcomings in both the pipeline design and the cooler design. The material was unevenly dispensed between the two coolers, which combined with the limited transport capacity of the coolers, led to overflowing and congestion of the whole system. Therefore, after visualization of the material flow and export of the necessary data using DEM design measures to mitigate these unwanted phenomena were carried out. [ABSTRACT FROM AUTHOR]