Papers by Keyword: Bulk Materials

Abstract: To extinguish flammable polar liquids, it is proposed to use a multicomponent fire extinguishing system consisting of one or two layers of wetted lightweight bulk materials. It has been established that wetting bulk materials leads to a significant increase in the following components of fire extinguishing action: cooling, insulation, and dilution. In addition, the introduction of water into the fire extinguishing system leads to a decrease in the concentration of vapors of polar flammable liquids above the fire extinguishing layer of bulk materials due to their absorption by water. Crushed foam glass with a granule size of 10-15 mm was selected as a bulk material for the formation of the base layer of the fire extinguishing system. To improve the insulating properties of the base layer, it is proposed to apply swollen perlite with a granule size of 1.0-1.4 mm or swollen lamellar vermiculite with a scale size of 1 × 2.5 mm to its surface. Such sizes of perlite and vermiculite particles enable them to fill the cavities between the granules of the foam glass base layer, which leads to an increase in the insulating properties of the fire extinguishing system. The following were experimentally determined: bulk density, buoyancy in methanol, ethanol, propanol-2, and acetone, moisture retention of bulk materials, and the fraction of material that spilled through the foam glass layer. The fire extinguishing capacity of the proposed fire extinguishing systems based on bulk materials in the case of extinguishing polar flammable liquids was experimentally determined. The systems based on bulk materials have a combined fire extinguishing effect by the following mechanisms of combustion termination: cooling, insulation, and dilution. It is concluded that the advantages of the proposed system in comparison with existing fire extinguishing agents for polar flammable liquids are substantiated.

Abstract: The article presents a new design of a hinged and sectional working body and substantiates its optimal parameters for ensuring the movement of loose materials along curvilinear routes. Analytical dependencies have been derived to determine the rational design and power parameters of the hinged-sectional working body, and the functional dependencies of the minimum permissible radius of curvature of the R_C technological highway on the angular rotation of adjacent sections and their design parameters have been established. The axial speed and power of cargo transportation by the articulated-sectional working body of the screw conveyor along a curved route have been determined. Experimental studies have been conducted to determine the influence of the number of revolutions, the height of material lifting and the radius of curvature of the flexible helical sectional working body R_C on the torque T, as well as the determination of the influence of the number of revolutions n, the filling factor of the main line ψ and the diameter of the main line D on the performance Q when transporting loose materials.

Abstract: Titanium has excellent mechanical properties, low density, high chemical stability, good heat transfer properties and a good corrosion resistance. In recent years, a new process technology is emerging by which titanium and titanium alloys can be made by sintering titanium hydride (TiH₂) and its mixture with alloying elements. The feasibility of this manufacturing approach has been fully demonstrated from powder to sintering and from microstructure to mechanical properties. This paper describes a study concerning Powder Metallurgy (PM) technology processing of Ti by conventional PM and non-conventional PM method such as Spark Plasma Sintering (SPS) route. The influence of the technological parameters on the micro-hardness and SEM microstructures during bulk titanium materials processing has been studied. The STATISTICA program has been used to monitor the influence of the technological parameters on the micro-hardness of bulk titanium processed products. The tribological behaviour of the bulk titanium materials on the basis of the coefficient of friction and wear rate is presented, too.

Abstract: Submission materials are the main manufacturing operation in the industry. It largely determines the quality parameters of products. Mechanization and automation of bulk material supply operation in the process eliminates human error and improves the product quality. This work was aimed at finding technical solutions that the reduction of specific energy consumption and enhance the reliability of the vibrating and pneumatic feeders. The article describes the developed the authors vibratory and pneumatic feeders.

Abstract: Any processing of bulk materials requires their moving and uniform feed (dosage). On this depends the quality and efficiency of many technological processes. For uniform and controlled supply of bulk, materials for transporting or processing machines use feeders. Among feeders in recent years, an increasing distribution received disk vibrating feeders, which are characterized by small size, without moving parts, prostate, reliability, accuracy and smooth control supply. Disk vibrating feeder has a horizontal spreading disk, which is located coaxially and with a gap below the outlet of the hopper. Spreading disk is connected with vibratory drive. This research was aimed at finding technical solutions ensuring the reduction of specific energy consumption of disk vibrating feeder. The study showed, that if the spreading disc perform with a central hole, which is closed by an elastic membrane, then this can significantly reduce the specific energy consumption per unit of production.

Abstract: For the non-harmonic vibration conveyor, a single-degree-of-freedom dynamics model is built for the horizontal motion of bulk materials, in which the dry friction force is piecewise nonsmooth. The effect on conveying velocity is studied for six vibration parameters in the excitation force with two harmonic components. The conveying velocity increases with the increase of frequency and amplitude, but the optimum frequency ratio is 2, and the optimum amplitude ratio approaches 1/3. The initial phase has no effect on conveying velocity, and the effect of phase difference is periodic, i.e. the forward conveying is best on phase difference π/2, and the backward conveying is best on phase difference -π/2.

Abstract: In the article the results of studying of the equipment up-to-date condition and grading bulk construction solids theoretical examining on different fractures especially damp materials of bed, lamellar and stylus forms were obtained. It is shown that operating now plane vibration or drum screens do not satisfy to the process of grading non-metallic materials. The article considers processes of screening bulk material on the spiral vibrating screen. The screen rational parameters, which provide product of the high quality, decreasing of consumed power and increasing of efficiency, were determined. Mathematical model of the spring spiral, a spiral vibrating screen is developed. Let’s study spring spiral in two positions - static and dynamic. In the result of making static and also dynamic models we got dependences for determining the lateral strain of spiral turns. Pre-condition for making the given model is the condition of complete spiral loading with input bulk material providing rational values of screening efficiency and effectiveness. The obtained mathemati-cal model of springing spiral, spiral vibration screen will allow to produce qualitative analysis of work of totally new innovating screen

Abstract: Lateral pressure is a key parameter to silos’ design. It has an important effect on the safety and efficiency of silos. The lateral pressure ratios that recommended by some overseas design codes and literatures have been analyzed. These ratios didn’t take into account the elasticity of silo wall, one of which is 28% smaller than the measure value, but another goes up to super pressure ratio. A new lateral pressure ratio is derived by considering the elasticity of silo wall, which is relevant to Passion ratio of stored material and relative stiffness coefficient . The coefficient of usual metal silo varies from 0.01 to 0.2, so it has significance to consider the wall elasticity.

Abstract: With the development of modern industry, silo diameters are bigger and bigger. Lateral pressure of bulk materials in silos is one important parameter for designing silos, which is related to the economy and safety of the structure. However, present calculation methods of the lateral pressure are mostly based on small diameter silos. For now, in the Chinese code the wall pressure computation methods are based on Rankine theory to be calculated. It is shown that the calculated results of Rankine theory may overestimate the pressure. In this paper, the lateral pressure of large diameter silos is studied. A new formula for calculating lateral static pressure on shallow silo wall is derived by static equilibrium method. The formula of this paper is simple of calculation and can be used for large diameter silos with a circular con top pile. The results agree with that of the full-sized silo experiment better than the current code.

Abstract: The two limit equilibrium methods of bulk material (Variation method and wedge model method) is employed to analyze models of sliding cuneiform volume of bulk solid, the lateral pressure formula for squat silos and equations of failure plane about sliding cuneiform volume are obtained. Variations of the positions of failure plane with height/diameter ratio are analized on the basis of the analysis for positions of failure plane by solution of these equation. The applied range and calculation method of the formula, and pressure distribution are discussed. The effects of friction between bulk solid and squat silos on the positions of failure plane and lateral pressure of bulk solid are discussed. The conclusion is that caculation results is available for squat silo design when the friction takes no into account, and the applied range of the formula is that height/diameter ratio equals 1.3. It is widely appicable for almost all squat silos. The caculation results agree with that of the full-sized silo experiment. This is a reasonable calculation method for design of squat silo.