Wyniki wyszukiwania - Biblioteka Nauki

1

Numerical simulations of the exploitation parameters of the rotary feeder

100%

Karwat B. , Rubacha P. , Stańczyk E.

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tom nr 4 (30)

Bibliogr. 33 poz., rys., tab.

EN

The article presents the problems of determining the mass efficiency of a rotary feeder depending on the selection of design parameters of the device, such as outer diameter, number of blades and rotational speed of the rotor. The hitherto theoretical methods of calculating the feeder efficiency were presented, as well as a new method of determining the device operation parameters was proposed. For this purpose, the numerical Discrete Element Method was used, which allowed simulating the transport of limestone powder in a cell feeder with various design variants. The results of the tests showed that the above design parameters affect the instantaneous efficiency of the feeder and thus impact the distribution of the dosed material during the operation of the device. Depending on the design solution, the simulation results gave information on the fill factor of the feeders. The study showed a significant potential of DEM simulation in the design of circular feeders intended for dosing bulk materials.

2

Wpływ wilgoci na zachowanie się materiałów sypkich. Cz. 2, Zmiana charakterystyki reologicznej

75%

Opaliński I. , Olechowski M. , Chutkowski M.

Przemysł Chemiczny

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2011

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tom T. 90, nr 10

1886-1889

3

Modelling of the flow of streams of cohesionless and cohesive bulk materials in a conveyor discharge point with a flat conveyor belt

63%

Cyganiuk J. A. , Kuryło P.

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tom Vol. 23, no. 1

23--35

EN

The paper presents the analysis of flow conditions of cohesive and cohesionless bulk materials in a conveyor discharge point of a flat conveyor belt. The analysis was carried out for stationary flows at high velocities. It presents mathematical methods for the description of the velocity of a material leaving a throwing point of a flat conveyor belt as well as final equations which enable the determination of velocity of the material after it has left the throwing point (with the accuracy sufficient for practical use). Next, the velocity calculated for the proposed mathematical description (for selected material groups) has been compared with the velocity obtained from mathematical relations commonly used by engineers. The proposed equations for determining the velocity of the material beyond the point have proved useful, since they enable excluding the indirect equations. Finally, the difference between the values of the velocity obtained with the proposed and indirect equations have been determined and the relative error for the proposed method has been calculated.

4

Niepożądane rozdrabnianie i segregacja. Materiały sypkie

63%

Domian E. , Cenkier J. , Wojnowski M.

Przemysł Spożywczy

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2013

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tom T. 67, nr 11

33--37

PL

W artykule przedstawiono czynniki wpływające na mechanizm złożonych zjawisk niepożądanego rozdrabniania i segregacji, metody ich oceny i zapobiegania na wybranych przykładach. Rozdrabnianie proszku wiąże się z rozpadem i zmniejszaniem wymiarów cząstek. Intensywne oddziaływanie mechaniczne sił tarcia cząstek o siebie i o elementy konstrukcyjne urządzenia w warunkach prowadzenia różnych procesów to podstawowy czynnik prowadzący do rozdrabniania produktów spożywczych, głównie w formie aglomerowanej, mających kruchą strukturę wielocząstkową. Opisano mechanizm działania tych sił w aspekcie rozdrabniania podczas przetwarzania i przemieszczania proszków spożywczych, jak też wpływu na produkt końcowy. Segregacja, mimo że powiązana ze rozdrabnianiem, jest ogólniejszym zjawiskiem, które wpływa na jakość produktu i produkcję. Niepożądane oddzielenie drobnych cząstek od dużych cząstek podczas różnych procesów przetwarzania i obrotu, takich jak transport pneumatyczny, mieszanie, załadunek i składowanie w masie, zostały wyjaśnione w różnych aspektach. Omówiono mechanizmy, metody oceny i zapobiegania segregacji proszków oraz różne okoliczności, gdzie segregacja może wystąpić.

EN

Factors affecting the mechanism of complex phenomena which undesirable fragmentation and segregation, assessment and prevention methods on the example of different applications will be presented in this article. Powder fragmentation is product related, and involves the breakdown of particles and particle size reduction. Intensive mechanical friction forces impact of particles with each other and construction elements machine under the conditions of the various processes is a key factor leading to the fragmentation of food powders, mainly in the form of agglomerated, because of their multi-particulate structure. Descriptions of how these forces intervene in food powders production and handling, and how the final product will be affected were given. Segregation, although related to attrition, is a more general phenomenon that affects both the products and production. The unwanted separation of fine particles from coarse particles during different handling and storage activities such as conveying, mixing, charging, and bulk storing, was explained from different aspects. Various circumstances where segregation can affect production, along with its physical mechanisms, were shown. Furthermore, different evaluation methods and minimization techniques will illustrate powder segregation prevention.

5

Microstructure of massive iron-carbon alloys obtained by mechanical alloying and sintering

51%

Nowosielski R. , Pilarczyk W.

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2007

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tom Vol. 28, nr 4

246-253

EN

Purpose: The ultimate aim of this work was to investigate structure and properties massive Fe-6.67%mass.C and Fe-0.4%mass.C materials obtained by mechanical alloying and sintering. Design/methodology/approach: The powders of the iron-carbon alloys obtained by mechanical alloying method and after that the powders were sintering. The sintering process was conducted by using the impulseplasma method. In this article the usability of mechanical alloying method and sintering to produce the massive Fe-C materials were presented. The morphology of voids of iron-carbon sinters was analyzed using the scanning electron microscopy method. The distribution of powder particles was determined by a laser particle analyzer. The observation of the shape and size of the grains was carried out by means of the LEICA optical microscope. Then one performed the measurements of the hardness with the Vickers method. The density of the sinters was measured using the Multivolume Pycnometer 1305. Findings: The laboratory tests show that, by using the mechanical alloying method, one can produce powder of Fe-6.67%mass.C and Fe-0.4%mass.C alloys with intentional chemical constitution and desirable structure. The structure of the alloyed materials is homogeneous and fine-grained and inside the materials didn't find some impurities and undesirable phases. The sintering by using the impulse-plasma method makes the sinters with close to theoretical density with non-variable nanocrystaline structure possible. The hardness of the sinters were 1300 HV and 250 HV adequately. Research limitations/implications: Property of Fe-C alloys correction is possible by refinement of grains and modification of phases composition. Nanocrystaline size of grain is advisable to make it in correct technology of producing bulk materials with nanocrystaline structure. All of the presented experiments in this article are made on a laboratory scale. At the present time, most often, the mechanical alloying and the sintering processes of nanocrystaline materials are only just in the laboratory scientific research. In the nearest future the producing of amorphous and nanocrystaline materials will take place not only in the laboratory scale and move to the industry. Originality/value: The powders produced by using mechanical alloying techniques can be use to produce bulk materials with desirable mechanical, physical and chemical properties.