The simulation of the particles movement during transport in the static mixer and modified screw conveyor using discrete element method

Kvalitetno mešanje praškastih materijala, čestica ili granula je od izuzetnog inženjerskog, energetskog, ekonomskog i ekološkog značaja u raznim granama industrije: prehrambenoj, procesnoj, hemijskoj, farmaceutskoj industriji. Efikasnost mešanja, dizajn opreme i parametri procesa mešanja imaju značajan uticaj na kvalitet i cenu poluproizvoda ili finalnog proizvoda. U ovoj tezi, prikazana je upotreba metode diskretnih elemenata (DEM) na modelovanje mešanja granula i/ili praškastih materijala (granulisani zeolit ili kukuruzna prekrupa) u različitim konfiguracijama statičkih mešača Komax i Ross, kao i za modifikovane pužne transportere / predmešalice. Primenjen je i metod računske dinamike fluida (CFD) za modelovanje protoka fluida u Ojlerovom višefaznom modelu, za predviđanje ponašanja čestica unutar različitih konfiguracija statičkih mešalica. Ispitivano je petnaest horizontalnih pužnih transportera sa nepromenljivog koraka, sa modifikovanom geometrijom, različitih dužina pužnice, sa dodatnim elementima na pužnoj spirali, radi istraživanja mogućnosti mešanja granulisanog materijala, tokom transporta materijala (granulisani zeolit). Rezultati matematičkog modeliranja i numeričke simulacije su upoređeni sa odgovarajućim eksperimentalnim rezultatima na osnovu stepena pomešanosti mešavine, primenom kriterijuma relativne standardne devijacije (RSD). Zahvaljujući ovde postavljenim modelima moguće je uraditi optimizaciju geometrije i parametara sistema mešanja uzimajući u obzir kvalitet procesa mešanja i cenu finalnog proizvoda.The quality mixing of powders, particles and/or granules obtain an engineering, energetic, economic and ecological importance of various technologies, food industry, pharmaceutical and chemical industry. The mixing efficiency, the design of equipment and mixing parameters exert a strong impact on quality and the price of intermediate or final product. In this thesis, the use of Discrete Element Method (DEM) is shown for modeling of granular and/or powder flow in various multiple Komax and Ross mixing applications, as well as for the modified screw conveyors premixers . Computational Fluid Dynamic (CFD) method was used for modeling of fluid flow through Eulerian multiphase model, for the prediction of particle displacement within the various static mixers configurations. Fifteen horizontal screw conveyors with invariant pitch, with modified geometry and different screw length , with some additional elements welded on the helix were tested for the possibility of granular material mixing during the material transport (granulated zeolite). The results of the numerical simulation are compared with appropriate experimental results, according to relative standard deviation criterion (RSD). Application of this model provide the optimization of the geometry and parameters of mixing systems taking into account the quality of the mixing process and the cost of the final product

The simulation of the particles movement during transport in the static mixer and modified screw conveyor using discrete element method

Kvalitetno mešanje praškastih materijala, čestica ili granula je od izuzetnog inženjerskog, energetskog, ekonomskog i ekološkog značaja u raznim granama industrije: prehrambenoj, procesnoj, hemijskoj, farmaceutskoj industriji. Efikasnost mešanja, dizajn opreme i parametri procesa mešanja imaju značajan uticaj na kvalitet i cenu poluproizvoda ili finalnog proizvoda. U ovoj tezi, prikazana je upotreba metode diskretnih elemenata (DEM) na modelovanje mešanja granula i/ili praškastih materijala (granulisani zeolit ili kukuruzna prekrupa) u različitim konfiguracijama statičkih mešača Komax i Ross, kao i za modifikovane pužne transportere / predmešalice. Primenjen je i metod računske dinamike fluida (CFD) za modelovanje protoka fluida u Ojlerovom višefaznom modelu, za predviđanje ponašanja čestica unutar različitih konfiguracija statičkih mešalica. Ispitivano je petnaest horizontalnih pužnih transportera sa nepromenljivog koraka, sa modifikovanom geometrijom, različitih dužina pužnice, sa dodatnim elementima na pužnoj spirali, radi istraživanja mogućnosti mešanja granulisanog materijala, tokom transporta materijala (granulisani zeolit). Rezultati matematičkog modeliranja i numeričke simulacije su upoređeni sa odgovarajućim eksperimentalnim rezultatima na osnovu stepena pomešanosti mešavine, primenom kriterijuma relativne standardne devijacije (RSD). Zahvaljujući ovde postavljenim modelima moguće je uraditi optimizaciju geometrije i parametara sistema mešanja uzimajući u obzir kvalitet procesa mešanja i cenu finalnog proizvoda.The quality mixing of powders, particles and/or granules obtain an engineering, energetic, economic and ecological importance of various technologies, food industry, pharmaceutical and chemical industry. The mixing efficiency, the design of equipment and mixing parameters exert a strong impact on quality and the price of intermediate or final product. In this thesis, the use of Discrete Element Method (DEM) is shown for modeling of granular and/or powder flow in various multiple Komax and Ross mixing applications, as well as for the modified screw conveyors premixers . Computational Fluid Dynamic (CFD) method was used for modeling of fluid flow through Eulerian multiphase model, for the prediction of particle displacement within the various static mixers configurations. Fifteen horizontal screw conveyors with invariant pitch, with modified geometry and different screw length , with some additional elements welded on the helix were tested for the possibility of granular material mixing during the material transport (granulated zeolite). The results of the numerical simulation are compared with appropriate experimental results, according to relative standard deviation criterion (RSD). Application of this model provide the optimization of the geometry and parameters of mixing systems taking into account the quality of the mixing process and the cost of the final product

Removal of mineral oil and wastewater pollutants using hard coal

This study investigates the use of hard coal as an adsorbent for removal of mineral oil from wastewater. In order to determine the efficiency of hard coal as an adsorbent of mineral oil, process parameters such as sorption capacity (in static and dynamic conditions), temperature, pH, contact time, flow rate, and chemical pretreatment were evaluated in a series of batch and continuous flow experiments. There were significant differences in the mineral oil removal for various pH values examined. The adsorption of mineral oil increased as pH values diverged from 7 (neutral). At lower temperatures, the adsorption was notably higher. The wastewater flow rate was adjusted to achieve optimal water purification. Equilibrium was reached after 10 h in static conditions. At that time, more than 99% of mineral oil had been removed. At the beginning of the filtering process, the adsorption rate increased rapidly, only to show a minor decrease afterwards. Equilibrium data were fitted to Freundlich models to determine the water-hard coal partitioning coefficient. Physical adsorption caused by properties of the compounds was the predominant mechanism in the removal process

Discrete element modelling of screw conveyor-mixers

Pužni transporteri se veoma intenzivno koriste u industriji za proizvodnju i preradu hrane, plastike, mineralnih sirovina, u poljoprivrednoj proizvodnji kao i u prerađivačkoj industriji za podizanje i/ili transport rasutih materijala na kratkim i srednjim rastojanjima. Uprkos njihovoj očiglednoj konstrukcionoj jednostavnosti, sam čin transporta je veoma složen za razumevanje i konstruktori se često oslanjaju na iskustvene podatke pri konstruisanju i izradi. Osobine pužnih transportera su određene radnim uslovima (kao što su: brzinu rotacije vratila puža, ugao pod kojim je nagnut pužni transporter, nivo zapreminskog punjenja puža, itd.). U ovom radu je opisano nekoliko horizontalnih puževa, konstantne dužine koraka, pri čemu su geometrije pužnih spirala neznatno izmenjene radi ispitivanja procesa mešanja tokom transporta, korišćenjem metode diskretnih elemenata (Discrete Element Method - DEM). Ispitivani su uticaji geometrijskih izmena na osobine pužnog transportera, različita konstrukciona rešenja pužne spirale su međusobno poređena, kao i efekti geometrijskih izmena na mešanje u toku transporta. Tokom transporta u pužnom transporteru, čestice padaju sa vrha pužne spirale na prvu sledeću slobodnu površinu pužne spirale i taj segment putanje čestice može da bude iskorišćen za dopunsko mešanje materijala tokom transporta. Putanja čestice se drastično povećava ugradnjom tri dodatne zavojne površine usmerene u istom pravcu kao i pužna spirala (1458,2 mm u poređenju sa 397,6 mm u slučaju pužnog transportera sa jednom spiralom). Skraćivanjem dodatnih zavojnica, koje su usmerene u istom smeru kao i pužna spirala, unekoliko se smanjuje putanja čestice, na dužinu od 1728,8 mm (usled prekidanja zavojnice na sredini pužnog transportera). Putanja čestice se produžava na 1764.4 mm, kada se ugrade dodatne zavojne površine koje su usmerene u suprotnom pravcu od pravca pužne spirale. Ugradnjom tri dodatna pravolinijske letve, dobijena je najduža putanja čestice: 2061,6 mm.Screw conveyors are used extensively in food, plastics, mineral processing, agriculture and processing industries for elevating and/or transporting bulk materials over short to medium distances. Despite their apparent simplicity in design, the transportation action is very complex for design and constructors have tended to rely heavily on empirical performance data. Screw conveyor performance is affected by its operating conditions (such as: the rotational speed of the screw, the inclination of the screw conveyor and its volumetric fill level). In this paper, horizontal, several single-pitch screw conveyors with some geometry variations in screw blade were investigated for mixing action during transport, using Discrete Element Method (DEM). The influence of geometry modifications on the performance of screw conveyor was examined, different screw designs were compared, and the effects of geometrical variations on mixing performances during transport were explored. During the transport, the particle tumbles down from the top of the helix to the next free surface and that segment of the path was used for auxiliary mixing action. The particle path is dramatically increased with the addition of three complementary helices oriented in the same direction as screw blades (1458.2 mm compared to 397.6 mm in case of single flight screw conveyor). Transport route enlarges to 1764.4 mm, when installing helices oriented in the opposite direction from screw blades. By addition of straight line blade to single flight screw conveyor, the longest particle path is being reached: 2061.6 mm

Discrete element modelling of screw conveyor-mixers

Pužni transporteri se veoma intenzivno koriste u industriji za proizvodnju i preradu hrane, plastike, mineralnih sirovina, u poljoprivrednoj proizvodnji kao i u prerađivačkoj industriji za podizanje i/ili transport rasutih materijala na kratkim i srednjim rastojanjima. Uprkos njihovoj očiglednoj konstrukcionoj jednostavnosti, sam čin transporta je veoma složen za razumevanje i konstruktori se često oslanjaju na iskustvene podatke pri konstruisanju i izradi. Osobine pužnih transportera su određene radnim uslovima (kao što su: brzinu rotacije vratila puža, ugao pod kojim je nagnut pužni transporter, nivo zapreminskog punjenja puža, itd.). U ovom radu je opisano nekoliko horizontalnih puževa, konstantne dužine koraka, pri čemu su geometrije pužnih spirala neznatno izmenjene radi ispitivanja procesa mešanja tokom transporta, korišćenjem metode diskretnih elemenata (Discrete Element Method - DEM). Ispitivani su uticaji geometrijskih izmena na osobine pužnog transportera, različita konstrukciona rešenja pužne spirale su međusobno poređena, kao i efekti geometrijskih izmena na mešanje u toku transporta. Tokom transporta u pužnom transporteru, čestice padaju sa vrha pužne spirale na prvu sledeću slobodnu površinu pužne spirale i taj segment putanje čestice može da bude iskorišćen za dopunsko mešanje materijala tokom transporta. Putanja čestice se drastično povećava ugradnjom tri dodatne zavojne površine usmerene u istom pravcu kao i pužna spirala (1458,2 mm u poređenju sa 397,6 mm u slučaju pužnog transportera sa jednom spiralom). Skraćivanjem dodatnih zavojnica, koje su usmerene u istom smeru kao i pužna spirala, unekoliko se smanjuje putanja čestice, na dužinu od 1728,8 mm (usled prekidanja zavojnice na sredini pužnog transportera). Putanja čestice se produžava na 1764.4 mm, kada se ugrade dodatne zavojne površine koje su usmerene u suprotnom pravcu od pravca pužne spirale. Ugradnjom tri dodatna pravolinijske letve, dobijena je najduža putanja čestice: 2061,6 mm.Screw conveyors are used extensively in food, plastics, mineral processing, agriculture and processing industries for elevating and/or transporting bulk materials over short to medium distances. Despite their apparent simplicity in design, the transportation action is very complex for design and constructors have tended to rely heavily on empirical performance data. Screw conveyor performance is affected by its operating conditions (such as: the rotational speed of the screw, the inclination of the screw conveyor and its volumetric fill level). In this paper, horizontal, several single-pitch screw conveyors with some geometry variations in screw blade were investigated for mixing action during transport, using Discrete Element Method (DEM). The influence of geometry modifications on the performance of screw conveyor was examined, different screw designs were compared, and the effects of geometrical variations on mixing performances during transport were explored. During the transport, the particle tumbles down from the top of the helix to the next free surface and that segment of the path was used for auxiliary mixing action. The particle path is dramatically increased with the addition of three complementary helices oriented in the same direction as screw blades (1458.2 mm compared to 397.6 mm in case of single flight screw conveyor). Transport route enlarges to 1764.4 mm, when installing helices oriented in the opposite direction from screw blades. By addition of straight line blade to single flight screw conveyor, the longest particle path is being reached: 2061.6 mm

Application of discrete element method for the transportat of seed in screw conveyor

Pužni transporteri imaju široku primenu u prehrambenoj industriji, građevinskim i rudarskim kompanijima, u hemijskoj, poljoprivrednoj i prerađivačkoj industriji, uglavnom za podizanje i / ili transport rasutih materijala na kratkim i srednjim rastojanjima. Uprkos njihovoj očiglednoj jednostavnosti, poboljšanje transportnih parametara je veoma zahtevan zadatak i inženjeri obično moraju da se oslanjaju na podatke dobijene empirijskim istraživanjima. U ovom radu, ispitivano je petnaest horizontalnih pužnih transportera sa konstantnim korakom pužnice, različite dužine, sa modifikovanom geometrijom. Ovi puževi su ispitivani radi mogućnosti pomoćnog mešanja tokom transporta materijala. Sva ispitivanja su rađena eksperimentalno i numerički, pomoću metode diskretnih elemenata (Discrete Element Method - DEM). Uticaji dužine puža, kao i predložene modifikacije geometrije u dizajnu pužne spirale, ipitivani su radi pomoćnog mešanja, tokom transporta granulisanog materijala kroz pužni transporter. Pomoćno mešanje (koje se koristi se za poboljšanje finalnog procesa mešanja) je postignuto tokom transporta materijala. Geometrija pužnog transportera se menja dodavanjem tri komplementarne spirale orijentisane u istom ili suprotnom smeru od pužne spirale. Čestice materijala se transportuju padaju dole sa vrha spirale do sledeće slobodne površine, i taj segment spirale je korišćen za dodatnu akciju mešanje. Prema eksperimentima i DEM analizema trajektorija čestice se povećava, sa primenjenim modifikacijama transportera, a ovakva geometrija može se koristiti za povećanje kvaliteta finalnog mešanja.Fifteen horizontal single-pitch screw conveyors with modified geometry and the different lengths were investigated for premixing action, during the transport of materials. All investigations were performed experimentally and numerically, by using Discrete Element Method (DEM). The influences of screw length, observed geometry variations and different types of screw design, on the performances of the screw conveyor-mixer during material transport were explored. The auxiliary mixing action was achieved during the transport of the material. The geometry of the screw conveyor is changed by adding three complementary helices oriented in the same or the opposite direction from screw blades. The particles of the material being transported tumble down from the top of the helix to the next free surface, and that segment of helix was used for additional mixing action. According to DEM analysis, particle path length is increased, and the improved geometry could be determined for increasing the quality of mixing

Protok granulisanog materijala u statičkoj mešalici, DEM/CFD pristup

The mixing process greatly influence the quality of the intermediate and/or the final product, moreover, the parameters of the mixing process and the design of used equipment have a strong impact on mixing efficiency, the quality and the price of the product. In this article, Discrete Element Method is used for modeling of granular flow in multiple static mixer applications (Komax and Ross configurations were utilized). Computational Fluid Dynamic method was chosen for fluid flow modeling, using Eulerian multiphase model. Coupling of these two methods provides reliable, sufficiently correct and adequate results of proposed model compared to experimental measurements. The aim of this article is to predict the behavior of granules in different mixer configuration and to optimize parameters of the mixing process taking into account the duration of the mixing process and the quality of mixture, as well as the price of final product.Proces mešanja veoma utiče na kvalitet krajnjeg poluproizvoda i/ili krajnjeg proizvoda, a parametri procesa mešanja i dizajn opreme veoma utiču na efikasnost mešanja, kvalitet proizvoda i cenu proizvoda. U ovom radu, prikazana je upotreba metode diskretnih elemenata (engl. Discrete Element Method - DEM) na modelovanje mešanja granula u različitim konfiguracijama statičkih mešača (korišćene su različite Komax i Ross konfiguracije za mešanje). Za modelovanje protoka fluida primenjena je metoda računske dinamike fluida (engl. Computational Fluid Dynamic - CFD), korišćenjem Ojlerovog višefaznog modela. Povezivanjem rezultata ove dve metode dobija se pouzdan, dovoljno tačan i adekvatan model koji daje rezultate koji odgovaraju eksperimentalnim merenjima. Praćene su i analizirane trajektorije, brzine i ubrzanja čestica, u cilju procene kvaliteta procesa mešanja. Dobro poznati kriterijum za kvalitet mešanja, pod nazivom relativna standardna devijacija (RSD) je korišćen za ovu svrhu. Optimizacija dimenzija i parametara mešanja u statičkoj mešalici je izvedena korišćenjem matematičkog modeliranja. Cilj ovog rada je bio da se predvidi ponašanje granulamog materijala u različitim konfiguracijama mešalica i da optimizuje parametre procesa uzimajući u obzir trajanje procesa mešanja, kvalitet mešavine i cenu finalnog proizvoda mešanja. U istraživanju je primećeno da su Komax elementi primenljiviji, u poređenju sa Ross elementima, posebno kada je visina instalacije mala. Međutim, upotreba Ross je finansijski prihvatljivija, zbog njegove jednostavnije geometrije. Dodatna pregrada sa kvadratnim otvorima, koja se postavlja na izlazu iz statičke mešalice, koristi se da bi se umirilo kretanje granula na obodu cevi, kao i da smanji segregaciju granula

Application of discrete element method for the transportat of seed in screw conveyor

Pužni transporteri imaju široku primenu u prehrambenoj industriji, građevinskim i rudarskim kompanijima, u hemijskoj, poljoprivrednoj i prerađivačkoj industriji, uglavnom za podizanje i / ili transport rasutih materijala na kratkim i srednjim rastojanjima. Uprkos njihovoj očiglednoj jednostavnosti, poboljšanje transportnih parametara je veoma zahtevan zadatak i inženjeri obično moraju da se oslanjaju na podatke dobijene empirijskim istraživanjima. U ovom radu, ispitivano je petnaest horizontalnih pužnih transportera sa konstantnim korakom pužnice, različite dužine, sa modifikovanom geometrijom. Ovi puževi su ispitivani radi mogućnosti pomoćnog mešanja tokom transporta materijala. Sva ispitivanja su rađena eksperimentalno i numerički, pomoću metode diskretnih elemenata (Discrete Element Method - DEM). Uticaji dužine puža, kao i predložene modifikacije geometrije u dizajnu pužne spirale, ipitivani su radi pomoćnog mešanja, tokom transporta granulisanog materijala kroz pužni transporter. Pomoćno mešanje (koje se koristi se za poboljšanje finalnog procesa mešanja) je postignuto tokom transporta materijala. Geometrija pužnog transportera se menja dodavanjem tri komplementarne spirale orijentisane u istom ili suprotnom smeru od pužne spirale. Čestice materijala se transportuju padaju dole sa vrha spirale do sledeće slobodne površine, i taj segment spirale je korišćen za dodatnu akciju mešanje. Prema eksperimentima i DEM analizema trajektorija čestice se povećava, sa primenjenim modifikacijama transportera, a ovakva geometrija može se koristiti za povećanje kvaliteta finalnog mešanja.Fifteen horizontal single-pitch screw conveyors with modified geometry and the different lengths were investigated for premixing action, during the transport of materials. All investigations were performed experimentally and numerically, by using Discrete Element Method (DEM). The influences of screw length, observed geometry variations and different types of screw design, on the performances of the screw conveyor-mixer during material transport were explored. The auxiliary mixing action was achieved during the transport of the material. The geometry of the screw conveyor is changed by adding three complementary helices oriented in the same or the opposite direction from screw blades. The particles of the material being transported tumble down from the top of the helix to the next free surface, and that segment of helix was used for additional mixing action. According to DEM analysis, particle path length is increased, and the improved geometry could be determined for increasing the quality of mixing

Modeling of combat operations

Introduction/purpose: The goal of the research in this paper is to present and evaluate the method of modeling operations by aggregating forces by simulating the battle process with Lanchester's equations. This method is the software basis of a certain number of programs used in NATO, in war simulations, and in the planning and analysis of operations. Its value is in understanding the consequences of decisions made with outcomes and results of combat actions. Methods: The case study of the well-known Operation Desert Storm gathered the necessary data on operational parameters and the way forces are used in battles. The obtained data were transformed into operational variables of the combat model using the force aggregation method, whose simulation was carried out using the method of differential Lanchester's equations (quadratic law). Results: By simulating the modeled operation, the parameters of the outcome of the conflict were obtained with numerical indicators of success, consumption of resources, etc. The results were analyzed and a certain correlation with the parameters of the real operation was determined, which enables the validation of the model. Conclusion: The partial validity of the model describing the conflict on a practical historical example from a case study was confirmed. There are objective limitations in the application of modeling of military operations and optimization of the use of forces. The value of this method is the possibility of a reliable strategic assessment of the adversary's military power at the strategic level

New Approach to Multi-Criteria Ranking of the Copper Concentrate Smelting Processes based on the PROMETHEE/GAIA Methodology

Although the production of copper and its usage has been known for thousands of years, the search for the optimal process of its production is still in progress. The removal of the negative impacts of a certain technology could cost more, over a period of time, than the initial investment in the selection of the optimal technology process which would consider these effects. Hence, the selection should be supported by the innovative and modern tools, such as the applying of the multi-criteria analysis. This paper presents the implementation of the PROMETHEE/GAIA methodology for the ranking of the appropriate technological pyrometallurgical smelting process for the copper concentrate based on the eleven parameters which recognize the economic, ecological and technical aspects of the technological process. The implementation of the multi-criteria decision-making presented in this paper can be deemed as a contribution to the decision making tools, that is, to the one who makes a decision on the selection of the appropriate technological facility for smelting of the copper concentrates. The decision-makers faced with the practical need of evaluating and selecting the most appropriate technological process for pyrometallurgical copper extraction will get the greatest benefit from this multi-criteria model. The innovative contribution of this paper is also presented in the obtained model which systematically analyzes the ecological, economic and technical parameters of the copper extraction process