571 KB60 KB199820252016Dreu, RokJaklič, Miha TomažKočevar, KlemenSrčič, Stankoštevilka:1letnik:63str. 62-76ISSN:1318-0207COBISSID:4034929URN:URN:NBN:SI:doc-E8SMLY7AenSlovensko kemijsko društvoActa chimica slovenicaceviFarmacevtska tehnologijagranularni tokkemijska procesna tehnikapretok praškovtokovni parametritransportni procesiGranular matter transport in vertical pipes| the influence of pipe outlet conditions on gravity-driven granular flow|Gravity transport of granular materials in vertical pipes is one of the most fundamental steps in bulk powder handling and processing. Presented study investigates powder flow characteristics in vertical pipes with open and closed outlets and condition of free powder fall. Powder flow of pharmaceutical grade powders was observed in transparent, vertical pipe model. Description of flow structures was performed. Powder volume flow rate, acceleration, and dilatation were quantified and correlated with powder properties. The results show that in pipes with a closed outlet the escaping air slows down the powder flow, resulting in a much slower flow than in pipes with an open outlet. A dense granular flow was detected in an open outlet condition, whereas in a closed outlet condition two concurrent flow regimes were observed: a slow moving, dense powder bed, and a fast dilute powder flow. Differences in flow regimes may promote segregation, with important implications to industrial processesGravitacijski transport granularnih snovi po vertikalnih cevnih povezavah je osnoven in hkrati ključen proces, ki se odvija pri procesiranju granularnih snovi. Proučevali smo tokovne strukture farmacevtskih praškov pri različnih pogojih izpusta vertikalne cevne povezave: zaprta cev, odprta cev in izpust brez cevi. Granularni tok smo opazovali na steklenem, prosojnem, laboratorijskem modelu vertikalne cevne povezave. Opisali smo tokovne strukture padajočih praškov, s slikovno analizo pa smo kvantificirali tokovne parametre (volumski pretok, pospeški, dilatacija) in jih korelirali z izmerjenimi lastnostmi praškov. Volumski pretok praškov v cevi z zaprtim dnom je za red velikosti manjši v primerjavi s pretokom v cevi z odprtim dnom. V cevi z zaprtim dnom se granularni tok pod vplivom izhajajočega zraka organizira v dva tokovna režima: počasen tok gostega nasutja praškov in hiter, redek tok praškov, dispergiranih v izhajajočem zraku. V cevi z odprtim dnom smo opazili hiter, gosti tok granularne snovi. Razlike med opisanimi tokovnimi režimi dveh pogojev izpusta so lahko osnova za segregacijo granularne snovi, kar lahko kritično vpliva na industrijske tehnološke proceseTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaSlovensko kemijsko društvo