Drying оf suspensions in moving bed of inert particles

Sušеnjе је оpеrаciја kоја је vеоmа zаstuplјеnа u hеmiјskој, prеhrаmbеnој i fаrmаcеutskој industriјi i kао tаkvа prеdstаvlја znаčајnоg kоrisnikа еnеrgiје. Izbоr аdеkvаtnоg sistеmа zа sušеnjе је slоžеn prоcеs i zаhtеvа pоtpunо pоznаvаnjе kаrаktеristikа pоlаznоg mаtеriјаlа kао i оčеkivаnih kаrаktеristikа finаlnоg prаškаstоg prоizvоdа. Pоstupci sušеnjа sе intеnzivnо istrаžuјu u svеtu sа cilјеm pоvеćаnjа еnеrgiјskе еfikаsnоsti, rаzvоја štо kоmpаktniје оprеmе, pоbоlјšаnjа kоntrоlе rаdnоg rеžimа prоcеsа, оdržаnjа kvаlitеtа prоduktа i оptimаlnоg kаpаcitеtа, smаnjеnjа еmisiје zаgаđivаčа. Sušеnjе vlаžnih mаtеriјаlа u pоkrеtnim slојеvimа inеrtnih čеsticа је rеlаtivnо nоvа tеhnоlоgiја i prеdstаvlја еkоnоmičniјu i еfikаsniјu аltеrnаtivu оstаlim, trеnutnо nајčеšćе kоrišćеnim, mеtоdаmа u cilјu dоbiјаnjа visоkо kvаlitеtnоg оsušеnоg prаškаstоg prоduktа. Istrаživаnjа izvršеnа u оkviru оvоg rаdа su u pоtpunој sаglаsnоsti sа nајnоviјim svеtskim trеndоvimа, s оbzirоm dа је pоslеdnjih gоdinа uоčеn znаtаn pоrаst nаučnih istrаživаnjа pоsvеćеn sušеnju mаtеriјаlа u pоkrеtnim slојеvimа inеrtnih čеsticа. Prikаzаni su rеzultаti istrаživаnjа prоcеsа sušеnjа rаstvоrа i suspеnziја u sistеmimа sа pоkrеtnim slојеvimа inеrtnih čеsticа, u fluidizоvаnоm slојu i fоntаnskоm slојu sа cеvnim umеtkоm. Еkspеrimеntаlnа ispitivаnjа su rаđеnа nа lаbоrаtоriјskim аpаrаturаmа i nа uvеćаnim lаbоrаtоriјskim (pоluindustriјskim) urеđајimа. U rаdu su prikаzаni rеzultаti dоbiјеni pri trеtmаnu suspеnziја rаzličitih mаtеriјаlа Ispitivаn је uticај оpеrаtivnih uslоvа nа pеrfоrmаnsе sistеmа zа sušеnjе i nа kvаlitеt prаškаstоg prоduktа. Prаćеnjеm аkumulаciје оsušеnоg mаtеriјаlа u slојu inеrtnih čеsticа sа vrеmеnоm i prоmеnе fluidо-dinаmičkih pаrаmеtаrа ispitivаn је uticај pоčеtnоg sаstаvа i vrstе suspеnziје kао i tеrmičkih pаrаmеtаrа sušеnjа nа kоntinuаlnоst prоcеsа. Izvršеnа је аnаlizа еfikаsnоsti sušеnjа i еnеrgiјskе еfikаsnоsti u funkciјi rаzlikе tеmpеrаturа izmеđu ulаznоg i izlаznоg vаzduhа u cilјu bоlјеg sаglеdаvаnjа pеrfоrmаnsi sistеmа zа sušеnjе sа еnеrgiјskоg аspеktа. Izvršеnа su prеliminаrnа ispitivаnjа nаknаdnоg dоsušivаnjа i hlаđеnjа prаškаstоg prоduktа iz primаrnе sušnicе u cilјu оbеzbеđivаnjа zаhtеvаnе rеziduаlnе vlаžnоsti prоduktа i еliminisаnjа njеnоg nаknаdnоg pоvеćаnjа. Ustаnоvlјеnо је dа ukupni bilаnsi prеnоsа mаsе i tоplоtе аdеkvаtnо prеdviđајu rаdni rеžim sistеmа zа sušеnjе u fluidizоvаnоm slојu inеrtnоg mаtеriјаlа. Rаzviјеn је mоdеl zа prеdviđаnjе pеrfоrmаnsi sušnicе sа fоntаnskim slојеm inеrtnih čеsticа i cеntrаlnоm cеvi. Моdеl bаzirа nа јеdnаčinаmа kоntinuitеtа, bilаnsimа kоličinе krеtаnjа zа fluid i čеsticе i bilаnsimа zа prеnоs tоplоtе i mаsе pоstаvlјеnim zа cеvni umеtаk. Prаktičnо kоrišćеnjе mоdеlа zаhtеvа i kоrеlаciје zа prеdviđаnjе kоеficiјеnаtа trеnjа fluid-čеsticе, fluid-zid trаnspоrtnе cеvi i čеsticе-zid trаnspоrtnе cеvi. Prеdlоžеni mоdеl zа sušеnjе suspеnziја u sušnici sа fоntаnskim slојеm i cеvnim umеtkоm, pоrеd izvеsnih оgrаničеnjа, sе mоžе iskоristiti zа оdrеđivаnjе оptimаlnih kаrаktеristikа оvаkvе sušnicе i zа rеdukоvаnjе brоја еkspеrimеntаlnih prоbа. Rаzviјеn је mоdеl zа prеdviđаnjе brzinе cirkulаciје inеrtnih čеsticа, štо је оd izuzеtnоg znаčаја zа prојеktоvаnjе i kоntrоlu prоcеsа sušеnjа u sušnici sа fоntаnskim slојеm inеrtnih čеsticа i cеvnim umеtkоm. Rаzviјеnа је i еkspеrimеntаlnо vеrifikоvаnа mеtоdа zа prеdviđаnjе brzinе zаgušеnjа i pоrоznоsti u vеrtikаlnоm pnеumаtskоm trаnspоrtu inеrtnih čеsticа. Ustаnоvlјеnо је dа је sušеnjе suspеnziја nа inеrtnim čеsticаmа јеdnоstаvnа i vrlо еfikаsnа tеhnikа zа svе mаtеriјаlе kојi sе nеćе slеpiti zа inеrtnе čеsticе i nа tај nаčin izаzvаti sintеrоvаnjе slоја. Nа оsnоvu pоrеđеnjа pеrfоrmаnsi dvа ispitivаnа sistеmа prоizilаzi dа је sušеnjе u fluidizоvаnоm slојu inеrtnih čеsticа еfikаsniјi prоcеs. Prеdnоsti оvоg sistеmа su i mаnjа kоličinа inеrtnih čеsticа, mаnji pаd pritiskа, јеdnоstаvniја rеgulаciја prоcеsа i znаtnо јеdnоstаvniје uvеćаnjе rаzmеrа prоcеsа. Sа drugе strаnе, prеdnоst sušеnjа nа inеrtnim čеsticаmа u fоntаnskоm slојu sа cеvnim umеtkоm је vrlо krаtkо vrеmе bоrаvkа mаtеriјаlа u zоni sušеnjа. U оvоm sistеmu mоgućе је sušiti i nеkе mаtеriјаlе kојi sаdržе оrgаnskе i biоlоškе kоmpоnеntе, štо prеdstаvlја оsnоvnu prеdnоst u оdnоsu nа sušnicu sа fluidizоvаnim slојеm inеrtnih čеsticа uslеd mаnjеg rizikа оd slеplјivаnjа slоја.Drying is one of the most involved process in the chemical, pharmaceutical and food processing industries and accordingly this unit operation is the most energy consuming industrial operation. The adequate dryer selection is a complex process and in that purpose it is necessary to completely know the feed characteristics as well as expected characteristics of final powdery product. The rapid investigations in drying technology are associated with the higher energy efficiency, enhanced drying rates, development of more compact dryers, better proces control, enhanced product quality and optimal capacity, emission reduction. Drying of wet materials in moving beds of inert particles is a relatively novel technology and it represents more economical and more efficient alternative to other most commonly used drying technologies to produce the high quality powdery materials. The investigations performed in the scope of this work are in the full agreement with the latest world trends regarding to the significant progress in the researches of drying processes in the moving beds of inert particles, especially in the last few years. The results of solution and suspension drying in moving beds of inert particles, i.e. fluidized and draft tube spouted beds, are represented. The experimental investigations were conducted on laboratory and pilot scale. The results obtained from drying experiments conducted with various suspensions are presented. The influence of operational conditions on drying system performance and powdery product quality are investigated. The effect of the initial moisture content, physical and rheological properties of the suspensions as well as the effect of thermal parameters on continuity and stability of drying proces were investigated concerning the dried product accumulation in the bed with time and fluid-dynamic parameters change. The analysis of drying and energy efficiencies as functions of temperature diference between inlet and outlet air were performed for deeper insight in dryer behavior and operation from an energy point of view. The preliminary investigations of subsequent drying and cooling of powdery product from the primary drier were carried out in order to preserve the requested product residual moisture and to eliminate the posibility of residual moisture additional rise. It was maintained that overall heat and mass balances predict the fluidized bed dryer performance quite well. The model for predicting the draft tube spouted bed dryer performance were developed. The drying model are based on continuity equations, momentum equations for fluid and particles, heat and mass balances applied for draft tube. Practical applications of the model require relations for the fluid-particle interphase drag coefficient, the fluid-wall friction coefficient and the particle-wall friction coefficient. Some fluid mechanical and mass and heat transfer uncertainties limit model applicability, but predictions from proposed model seem to be useful for preliminary design and simulation and for reduction of experimental trials. The model for predicting the inert particle circulation rate were developed, that is of great importance for design and control of drying process in draft tube spouted bed dryer. The metod for predicting the choking velocity and porosity in vertical pneumatic transport were developed and experimentaly verified. It was maintained that drying of suspensions in moving beds of inert particles is a simple and very effective technique for non-sticky materials that do not adhere permanently to the inert particles. On the basis of comparison of two investigated drying systems follows that drying in fluidized bed of inert particles is more efficient process. The advantages of this system are also the lower pressure drop, the simpler process regulation and the significantly easier scale-up. On the other side, the advantage of drying on inert particles in draft tube spouted bed is the very short dried material residence time within drying zone. In comparison with fluidized bed dryer the main advantage of spouted bed dryer is that drying of some organic and biological materials can be conducted since the risk of bed sintering is much smaller

High efficiency disperse dryer - an innovative process for drying of solutions, suspensions and pastes in a fluidized bed of inert particles

In this paper, an innovative fluidized bed dryer with inert particles is presented. The system can be used for drying of solutions, suspensions and pastes in order to obtain a powdered product. The experiments were performed in a pilot-scale dryer with a cylindrical column 0.215 m in diameter and 1.2 mm height, with glass spheres as inert particles. The material used for drying was CuSO4 solution. The effects of operating conditions on the dryer throughput and product quality were investigated. Main performance criteria, i.e. specific water evaporation rate, specific heat consumption and specific air consumption, were quantified. Nearly isothermal conditions were found due to thorough mixing of the particles. The energy efficiency of the dryer was also assessed. Simple heat and mass balances predicted the dryer performance quite well

Vertikalno kretanje tečnosti i čvrstih čestica tretirano kao pseudo-fluid

The pseudo–fluid concept has been applied for the prediction of the pressure gradient and voidage in vertical liquid-coarse solids flow. Treating the flowing mixture as a single homogenous fluid, the correlation for the friction coefficient of the suspension–wall was developed, as was the correlation between the true voidage and the apparent (volumetric) voidage in the transport tube. Experiments were performed using water and spherical glass particles 1.20, 1.94 and 2.98 mm in diameter in a transport tube of 24 mm in diameter. The loading ratio (Gp/Gf) was varied between 0.05 and 1.05 and the fluid superficial velocity was between 0.4 Ut and 4.95 Ut where Ut represents the single particle terminal velocity. The voidage ranged from 0.648 to 0.951 for these ratios. Experimental data for the pressure gradient and voidage from the literature agree well with the proposed correlations.Za predviđanje gradijenta pritiska i poroznosti pri vertikalnom dvofaznom toku tečnosti i krupnih čvrstih čestica primenjen je koncept pseudofluida. Tretirajući pokretnu smešu tečnosti i čestica kao homogeni fluid, određena je zavisnost za koeficijent trenja suspenzija–zid transportne cevi, kao i zavisnost između stvarne i zapreminske (volumetrijske) poroznosti u transportnoj cevi. Eksperimentalna ispitivanja su izvedena u transportnoj cevi prečnika 24 mm, sa sferičnim staklenim česticama prečnika 1.20, 1.94 i 2.98 mm, pri čemu je kao transportni medijum korišćena voda. Opterećenje toka (Gp/Gf) variralo je između 0.05 i 1.05, dok se površinska brzina fluida kretala od 0.4.Ut do 4.95.Ut, gde je Ut brzina odnošenja usamljene čestice. Za navedene obime opterećenja toka i brzine fluida poroznost u sistemu se kretala od 0.648 do 0.951. Eksperimentalni podaci iz literature za gradijent pritiska i poroznost u dobroj su saglasnosti sa predloženim korelacijama

Predviđanje cirkulacije čestica u sušioniku za suspenzije sa modifikovanim fontanskim slojem

A model for predicting the particle circulation rate in a draft tube spouted bed dryer with inert particles is proposed and verified. The calculation algorithm requires three input values: the gas velocity in the draft tube one data point for the static pressure in the draft tube, and the pressure gradient in the annulus. The particle circulation rate can be estimated by solving the continuity and momentum equations for turbulent accelerating two-phase flow. The numerical solution is based on an iterative procedure until the assumed value of the particle circulation rate produces the prescribed value of the fluid static pressure at a certain axial position. Experiments were performed in a cylindrical column of 215 mm diameter with a draft tube of 70 mm diameter and length of 900 mm. Polyetylene pellets were used as the inert particles with a diameter of 3.3 mm, a density of 921 kg/m3 and a sphericity of 0.873. The model predictions of the particle circulation rate are in good agreement with the experimental data.Postavljen je model za predviđanje brzine cirkulacije čestica u sušioniku sa fontanskim slojem inertnih čestica i centralnom cevi. Predloženi model je eksperimentalno verifikovan. U algoritmu proračuna egzistiraju tri veličine kao poznate (ulazni parametri): brzina gasa kroz centralnu cev, jedna vrednost statičkog pritiska u centralnoj cevi i gradijent pritiska u anularnoj zoni. Brzina cirkulacije čestica se izračunava iz jednačina kontinuiteta i bilansa količine kretanja za turbulentni dvofazni tok fluid-čestice.Numeričko rešavanje se zasniva na metodi probe i greške iterativnim postupkom, sve dok se na osnovu predpostavljene vrednosti brzine čestica ne dobije vrednost statičkog pritiska fluida koja je jednaka izmerenoj vrednosti na određenoj aksijalnoj poziciji u centralnoj cevi. Eksperimentalna ispitivanja su izvedena u koloni prečnika 215 mm sa centralnom cevi prečnika 70mm i dužine 900 mm. Fontanski sloj je obrazovan od nesferičnih polipropilenskih čestica ekvivalentnog prečnika 3,3mm sferičnosti 0,873 i gustine 921 kg/m3. Dobijeni rezultati za brzinu čestica u centralnoj cevi su u dobroj saglasnosti sa eksperimentalnim podacima

Sušenje suspenzija i pasta u fluidizovanom sloju inertnog materijala

A fluid bed dryer with inert particles was used for the drying of suspensions and pastes. The effects of the operating conditions on the dryer throughput and on the product quality were investigated. Experiments were performed in a cylindrical column 215 mm in diameter and 1200 mm in height with 0.925 mm diameter glass spheres as the fluidizing media. Cineb fungicide, copper hydroxide and pure water were used as the feed material. With respect to the main efficiency criteria, i.e., specific water evaporation rate, specific heat consumption and specific air consumption, a fluid bed dryer with inert particles represents a very attractive alternative to other drying technologies. A high drying efficiency results from the large contact area and from the large temperature difference between the inlet and outlet air. A rapid mixing of the particles, due to aggregative fluidization and mechanical agitation, leads to nearly isothermal conditions throughout the bed. In our experiments, suspensions and very dense pastes were successfully treated. Suspension and product hold-up in the bed varies between 6 and 8 % by mass and a product with the same particle size as the raw material is obtained. .Izvršeni su ogledi sušenja suspenzija i pasta u fluidizovanom sloju inertnog materijala. Ispitivan je uticaj operativnih uslova na kapacitet sušionika i kvalitet produkta. Eksperimenti su izvršeni u cilindričnoj koloni prečnika 215 mm i visine 1200 mm. Kao inertne fluidizovane čestice korišćene su staklene sfere prečnika 0.925 mm. Tretirane su suspenzije cineb fungicida, bakar hidroksida kao i čista voda. U odnosu na osnovne kriterijume efikasnosti, tj. u pogledu specifične isparljivosti, specifične potrošnje toplote i specifične potrošnje vazduha sistem sušenja u fluidizovanom sloju inertnog materijala predstavlja vrlo atraktivnu alternativu ostalim tehnikama sušenja. Visoka efikasnost sušenja posledica je velike kontaktne površine i velike razlike temperatura između ulaznog i izlaznog vazduha. Intenzivno mešanje inertnih čestica usled agregativne fluidizacije i mehaničkog mešanja ima za posledicu približno ravnomernu temperaturu po celom volumenu sloja. U našim ogledima uspešno su tretirane retke suspenzije i vrlo guste paste. Hold-up materijala koji se suši u sloju kreće se od 6 do 8 mas. %, a u svim ogledima granulometrijski sastav produkta je praktično isti sa granulometrijskim sastavom polazne suspenzije odnosno paste

Drying of solutions and suspensions in the modified spouted bed with draft tube

A modified spouted bed dryer with inert particles was used for drying of solutions and suspensions. The effects of the operating conditions on dryer throughput and product quality were investigated. Experiments were performed in a cylindrical column 215 mm in diameter and 1150 mm in height with a draft tube 70 mm in diameter and 900 mm length. The bed was made of polyethylene particles 3.3 mm in diameter and of density of 921 kg/m3. The pesticide Cineb, inorganic compound calcium carbonate, organic compound calcium stearate, and pure water were used as feeding materials. A drying model using the continuity and momentum equations for turbulent accelerating two-phase flow and conventional rate equations is proposed and discussed. The work is relevant for estimating dryer performance

Sušenje mulja iz procesa prečišćavanja otpadnih voda u fluidizovanom sloju inertnih čestica

Waste water treatment sludge is generated in increasing quantities, as the amount of treated municipal and industrial waste water increases. Also, the requirements concerning the conditions of sludge storage/landfill or reuse are growing. Due to these reasons, new solutions regarding sludge treatment, management and utilization are needed [1]. The benefits of drying waste water treatment sludge can be seen in several aspects: the dried sludge can be stored for longer periods of time and further used as an organic fertilizer, it can be a source of useful (active) microorganisms that can be reused in waste water treatment. Drying also enables incineration or co-incineration of sludge. Sludge drying process reduces mass and volume of the product, making its storage, transport, packaging and retail easier [2-4].ušenjem mulja iz procesa prečišćavanja otpadnih voda mogu se dobiti dva glavna upotrebljiva proizvoda: osušeni mulj može se skladištiti i koristiti kao organsko đubrivo, a može sadržati i aktivne (žive) mikroorganizme koji se ponovo mogu koristiti u tretmanu otpadnih voda. Sušenje suspenzija i pasta u fluidizovanom sloju inertnih čestica predstavlja atraktivnu alternativu ostalim postupcima sušenja u pogledu osnovnih kriterijuma za ocenu efikasnosti kao što su specifični kapacitet isparavanja, specifični utrošak toplote i specifični utrošak vazduha. Visoka efikasnost sušenja je rezultat velikih kontaktnih površina i velikih temperaturnih razlika između ulaznog i izlaznog toka vazduha za sušenje. Intenzivno mešanje inertnih čestica tokom agregativne fluidizacije obezbeđuje približno jednaku temperaturu u celoj zapremini sloja te ne postoji rizik od lokalnog pregrevanja. U radu su prikazani rezultati ispitivanja sušenja mulja na pilot postrojenju za sušenje suspenzija i pasta nominalnog kapaciteta isparavanja do20 kgH2O/h, čiji je centralni deo cilindrična kolona prečnika 215 mm sa fluidizovanim slojem staklenih sfera. Ispitivan je uticaj operativnih uslova na performanse sistema za sušenje i na kvalitet praškastog osušenog aktivnog mulja. Glavni cilj je da se odrede optimalne temperature sušenja mulja pri kojima bi korisni mikroorganizmu u mulju ostali aktivni (živi), a pri kojim aktivni mulj može da se koristi kao oragansko đubrivo. Izvršena je analiza efikasnosti sušenja sa stanovišta kapaciteta isparavanja i potrošnje vazduha u cilju boljeg sagledavanja performansi sistema za sušenje. Jednostavni bilansi mase i toplote adekvatno predviđaju radni režim sistema za sušenje u fluidizovanom sloju inertnog materijala

Пренос масе у инверзно флуидизованом слоју

In this work, the coefficient of fluid-wall mass transfer in an inverse fluidized bed was determined using the adsorption method. The experiments were carried out in a column with a diameter of 45 mm with spherical and non-spherical particles of polypropylene and polyethylene with a diameter of 3.3-4.9 mm and a density of about 930 kg m-3. A diluted solution of methylene blue was used as a fluidization medium, which was adsorbed on part of the surface of the column on silica gel. The obtained results showed that the presence of particles during inverse fluidization does not contribute significantly to mass transfer compared to the influence of particles on transfer in conventional fluidized beds. Therefore, the pseudofluid concept was introduced into the analysis and an empirical correlation was performed to determine the mass transfer coefficient. The obtained results were compared with literature correlations for inverse and conventional fluidized beds.У овом раду је одређиван коефицијент преноса масе флуид-зид у инверзнофлуидизованом слоју применом адсорпционе методе. Експерименти су вршени у колони пречника 45 мм са сферичним и несферичним честицама полипропилена и полиетилена пречника 3.3-4.9 мм и густине око 930 кг м-3. Као флуидизациони медијум коришћен је разблажени раствор метиленски плавог који је адсорбован на делу површине колоне на силикагелу. Добијени резултати показали су да присуство честица при инверзној флуидизацији не доприноси значајно преносу масе у поређењу са утицајем честица на пренос масе у конвенционално флуидизованим слојевима. Због тога је у анализу уведен концепт псеудофлуида и изведена је емпиријска корелација за одређивање коефицијента преноса масе. Извршено је поређење добијених резултата са литературним корелацијама за инверзну и конвенционалну флуидизације

Ispitivanje dinamike granulacije praškastih materijala u fluidizovanom sloju

In this paper, experimental investigation of the dynamics of the process of fluidized bed granulation was performed, in order to find optimal process conditions and binder concentration to achieve the desired granules development. The experiments were performed in batch system using corn flour as starting material. Ten experiments were performed in which sucrose solution of different concentrations (20, 30, 35 and 40 %) was used as binder. The temperature of the system was kept constant during the granulation process and amounted to 40-50°C. Samples were taken from the fluidized bed at time intervals of 3 min. The dynamics of granulation was examined by determining three different factors (bulk density, moisure content and particle size distribution) for each of the samples. It has been found that bulk density continuously decreases during the granulation process, while in the drying phase it remains constant. Particle size distribution has shown that the average diameter of the projected surface increases uniformly during the process. By comparing all of the three investigated factors, it was shown that the best quality of granules is achieved using 35 % sucrose solution .U ovom radu izvršeno je eksperimentalno ispitivanje procesa mokre granulacije u fluidizovanom sloju u cilju pronalaženja optimalnih uslova izvođenja procesa i sastava veziva kojim će se ostvariti željena dinamika razvoja granula. Ispitivanje je izvršeno u šaržnom sistemu, a korišćeno je kukuruzno brašno kao polazni materijal. Izvršeno je 10 eksperimenata u kojima je kao vezivno sredstvo korišćen rastvor saharoze različitih koncentracija: 20, 30, 35 i 40 %. Temperatura je održavana konstantnom tokom procesa granulacije i iznosila je 40-50C. Uzorci su iz sloja uzimani u jednakim vremenskim intervalima od 3 min. Dinamika granulacije ispitivana je određivanjem tri različita faktora (nasipne gustina, vlažnosti i raspodele veličine čestica) za svaki od uzoraka. Utvrđeno je da nasipna gustina kontinualno opada tokom izvođenja procesa granulacije, dok u fazi sušenja ostaje konstantna. Raspodela veličina čestica je pokazala da srednji prečnik projektovane površine ravnomerno raste tokom procesa. Poređenjem sva tri ispitivana faktora pokazano je da se najbolji kvalitet granula postiže korišćenjem 35 % rastvora saharoze kao vezivnog sredstva.Related to: [http://cer.ihtm.bg.ac.rs/handle/123456789/3293

Ispitivanje dinamike granulacije praškastih materijala u fluidizovanom sloju

In this paper, experimental investigation of the dynamics of the process of fluidized bed granulation was performed, in order to find optimal process conditions and binder concentration to achieve the desired granules development. The experiments were performed in batch system using corn flour as starting material. Ten experiments were performed in which sucrose solution of different concentrations (20, 30, 35 and 40 %) was used as binder. The temperature of the system was kept constant during the granulation process and amounted to 40-50°C. Samples were taken from the fluidized bed at time intervals of 3 min. The dynamics of granulation was examined by determining three different factors (bulk density, moisure content and particle size distribution) for each of the samples. It has been found that bulk density continuously decreases during the granulation process, while in the drying phase it remains constant. Particle size distribution has shown that the average diameter of the projected surface increases uniformly during the process. By comparing all of the three investigated factors, it was shown that the best quality of granules is achieved using 35 % sucrose solution .U ovom radu izvršeno je eksperimentalno ispitivanje procesa mokre granulacije u fluidizovanom sloju u cilju pronalaženja optimalnih uslova izvođenja procesa i sastava veziva kojim će se ostvariti željena dinamika razvoja granula. Ispitivanje je izvršeno u šaržnom sistemu, a korišćeno je kukuruzno brašno kao polazni materijal. Izvršeno je 10 eksperimenata u kojima je kao vezivno sredstvo korišćen rastvor saharoze različitih koncentracija: 20, 30, 35 i 40 %. Temperatura je održavana konstantnom tokom procesa granulacije i iznosila je 40-50C. Uzorci su iz sloja uzimani u jednakim vremenskim intervalima od 3 min. Dinamika granulacije ispitivana je određivanjem tri različita faktora (nasipne gustina, vlažnosti i raspodele veličine čestica) za svaki od uzoraka. Utvrđeno je da nasipna gustina kontinualno opada tokom izvođenja procesa granulacije, dok u fazi sušenja ostaje konstantna. Raspodela veličina čestica je pokazala da srednji prečnik projektovane površine ravnomerno raste tokom procesa. Poređenjem sva tri ispitivana faktora pokazano je da se najbolji kvalitet granula postiže korišćenjem 35 % rastvora saharoze kao vezivnog sredstva.Related to: [http://cer.ihtm.bg.ac.rs/handle/123456789/3293