A downscaled rotary atomizer, operated in the regime of laminar thread breakup, is presented. The atomizer allows for producing dropsizes of 70 -200 mu m and narrow size distribution. Due to the special design of the rotary atomizer the drops are detaching with low velocity and the spray can easily be deflected. The new technology can be applied in small scale spray dryers for the production of powder samples with quantities of several kg h(-1). Pilot scale spray dryers were equipped with this type of atomizer in order to carry out scale-up experiments in small driers, but at particle sizes comparable to production-scale conditions.

Chemie Ingenieur TechnikVolume 85, Issue 9 p. 1422-1422 VortragFree Access Sprühtrocknung von Partikeln mit enger Größenverteilung durch Rotationszerstäubung und optimierte Gasverteilung Dr.-Ing. A. Mescher, Corresponding Author Dr.-Ing. A. Mescher axel.mescher@bci.tu-dortmund.de Technische Universität Dortmund, Fakultät Bio- und Chemieingenieurwesen, Lehrstuhl Mechanische Verfahrenstechnik, Emil-Figge-Straße 68, D-44227 Dortmund, GermanyTechnische Universität Dortmund, Fakultät Bio- und Chemieingenieurwesen, Lehrstuhl Mechanische Verfahrenstechnik, Emil-Figge-Straße 68, D-44227 Dortmund, GermanySearch for more papers by this authorM. Sc. J. Kamplade, M. Sc. J. Kamplade Technische Universität Dortmund, Fakultät Bio- und Chemieingenieurwesen, Lehrstuhl Mechanische Verfahrenstechnik, Emil-Figge-Straße 68, D-44227 Dortmund, GermanySearch for more papers by this authorProf. Dr. techn. P. Walzel, Prof. Dr. techn. P. Walzel Technische Universität Dortmund, Fakultät Bio- und Chemieingenieurwesen, Lehrstuhl Mechanische Verfahrenstechnik, Emil-Figge-Straße 68, D-44227 Dortmund, GermanySearch for more papers by this author Dr.-Ing. A. Mescher, Corresponding Author Dr.-Ing. A. Mescher axel.mescher@bci.tu-dortmund.de Technische Universität Dortmund, Fakultät Bio- und Chemieingenieurwesen, Lehrstuhl Mechanische Verfahrenstechnik, Emil-Figge-Straße 68, D-44227 Dortmund, GermanyTechnische Universität Dortmund, Fakultät Bio- und Chemieingenieurwesen, Lehrstuhl Mechanische Verfahrenstechnik, Emil-Figge-Straße 68, D-44227 Dortmund, GermanySearch for more papers by this authorM. Sc. J. Kamplade, M. Sc. J. Kamplade Technische Universität Dortmund, Fakultät Bio- und Chemieingenieurwesen, Lehrstuhl Mechanische Verfahrenstechnik, Emil-Figge-Straße 68, D-44227 Dortmund, GermanySearch for more papers by this authorProf. Dr. techn. P. Walzel, Prof. Dr. techn. P. Walzel Technische Universität Dortmund, Fakultät Bio- und Chemieingenieurwesen, Lehrstuhl Mechanische Verfahrenstechnik, Emil-Figge-Straße 68, D-44227 Dortmund, GermanySearch for more papers by this author First published: 23 August 2013 https://doi.org/10.1002/cite.201250641AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. REFERENCES 1 T.Schröder, P.Walzel, Chem. Ing. Tech. 1996, 68 (5), 562– 566. 2 A.Mescher, A.Möller, M.Dirks, P.Walzel, Chem. Eng. Sci. 2012, 69 (1), 181– 192. 3 A. Mescher, Dissertation, Technische Universität Dortmund 2012. Volume85, Issue9Special Issue: Jahrestagung der Fachgemeinschaft Fluiddynamik und TrenntechnikSeptember, 2013Pages 1422-1422 ReferencesRelatedInformation

As the morphology of spray dried aqueous mannitol solutions is strongly influenced by the scale of the used spray dryer or more correctly by the droplet size generated in the spray dryer the purpose of this work is to carefully study and compare the morphologies and underlying particle formation mechanisms on lab and pilot scale. Therefore drying experiments of 15% [w/w] aqueous mannitol solutions were performed on a lab and pilot scale spray dryer at different outlet temperatures. The obtained spray dried products are intended to be used as carrier particles for pulmonary drug delivery. In order to show that the morphology is highly dependent on the initial droplet size, irrespective of the size of the used spray dryer, droplets of different size were dried in the pilot scale spray dryer at different air outlet temperatures. Additionally the influence of feed temperature on particle morphology was studied.For small droplets crystallization from a highly viscous liquid or even water-free melt is observed, leading to rough particles at high outlet temperatures and smooth particles at low temperatures. When drying larger droplets, however crystallization obviously starts from a more diluted solution leading to rougher surfaces, containing larger single crystals at lower outlet temperatures than at higher ones. For large droplets an increase in the mannitol solution feed temperature leads to particles of comparably rougher surface. No influence of feed temperature was observed for smaller droplets. (C) 2013 Elsevier B.V. All rights reserved.

This work describes characteristic parameters (size, shape, morphology, bulk and effective particle density) of mannitol carriers intended for pulmonary drug delivery which had been prepared at spray drying outlet temperatures of 67 degrees C (M67), 84 degrees C (M84) and 102 degrees C (M102).Scanning electron microscopy (SEM) images showed clear differences in surface roughness and shape of the spray dried products. At low outlet temperatures spherical, rough particles were obtained whereas higher drying temperatures resulted in particles with multiple surface indentations and a smoother surface. It was possible to analyze surface roughness with confocal-scanning microscopy and SEM tilted-image analysis. Mercury intrusion porosimetry (MIP) turned out to be a highly valuable experimental tool for the determination of the effective particle density.All spray drying conditions resulted in the formation of particles with a shell and a core. The core is either hollow or filled with mannitol crystals. The inner hollow space volume decreases with increasing temperature. For this reason particles prepared at higher temperatures exhibit a higher mechanical stability (M67: 2.46 +/- 0.77 MPa; M84: 5.03 +/- 1.51 MPa; M102: 11,75 +/- 4,01 MPa). The products prepared at 67 degrees C showed the lowest bulk and effective particle densities. The effective particle densities were determined to be 0.832 +/- 0.002 g/cm(3) (M67), 1.004 +/- 0.008 g/cm(3) (M84) and 1.111 +/- 0.011 g/cm(3) (M102) respectively. (C) 2013 Elsevier B.V. All rights reserved.

A filtration system for keeping the analytics free of particles is usually required for inline characterization of particle-laden process gasses. Additionally gas pumps may be needed for overcoming the pressure drop of filter element and filter cake. Consecutive reactions of process gas and filter cake may be disadvantageous for the quality of the gas analysis. A new probing apparatus is presented for extraction of particle-free gas samples from particle-laden process gasses. The probe combines the functionalities of a gas pump and a particle separator. While the gas is transported from process to analysis, particles are separated according to the principle of air classification.

Aim of the present study was to investigate the impact of atomization and drying on the functionality of emulsions with a bilayered oil–water interface consisting of a globular protein (β-lactoglobulin, bLG) and anionic polysaccharides (pectins with varying degree of methoxylation). With regard to the atomization process, the emulsion spray droplet size generally decreased with increasing atomization energy. The spray droplet size distribution was narrower with rotary atomization compared to two-fluid nozzle atomization. The single droplet drying behaviour of the differently stabilized emulsions was similar as examined by acoustic levitation. With more than 95%, microencapsulation efficiency was high in all spray-dried particles. However, a shift in oil droplet size upon reconstitution indicated that oil droplet coalescence occurred within the process which was less pronounced in bilayer emulsions compared to the bLG-stabilised single layer emulsion. Data from interfacial viscoelasticity measurements showed distinct differences, which may explain oil droplet coalescence. The oxidative stability of encapsulated oil was influenced by both the physical state of the emulsions and the different constituents at the o/w-interface with bLG and low methoxylated pectin giving the best protection of the oil.

The aim of this study was to characterize the process of atomization and drying of layer-by-layer emulsions containing lecithin (single layer emulsion) and lecithin/chitosan (bilayer emulsion) and the oxidative stability of the microcapsules during storage. For this purpose, the analysis of the emulsion spray droplet size during two-fluid nozzle and rotary atomization was carried out to identify suitable process parameters. The drying behaviour of single and bilayer emulsions was investigated by calculation of the volume flow density during single-droplet drying during acoustic levitation. In spray-dried solid particles, the oxidative stability in the single layer microcapsules was higher than in the bilayer microcapsules. This was partly attributed to lower microencapsulation efficiency in the bilayer microcapsules compared to the single layer microcapsules. Furthermore, it could be shown, that excess chitosan in the bulk carrier matrix affects the free volume elements and thus oxygen diffusion.

Powders intended for the use in dry powder inhalers have to fulfill specific product properties, which must be closely controlled in order to ensure reproducible and efficient dosing. Spray drying is an ideal technique for the preparation of such powders for several reasons. The aim of this work was to investigate the influence of spray-drying process parameters on relevant product properties, namely, surface topography, size, breaking strength, and polymorphism of mannitol carrier particles intended for the use in dry powder inhalers. In order to address this question, a full-factorial design with four factors at two levels was used. The four factors were feed concentration (10 and 20% [w/w]), gas heater temperature (170 and 190 degrees C), feed rate (10 and 20 L/h), and atomizer rotation speed (6,300 and 8,100 rpm). The liquid spray was carefully analyzed to better understand the dependence of the particle size of the final product on the former droplet size. High gas heater temperatures and low feed rates, corresponding to high outlet temperatures of the dryer (96-98 degrees C), led to smoother particles with surfaces consisting of smaller crystals compared to those achieved at low outlet temperatures (74-75 degrees C), due to lower gas heater temperatures and higher feed rates. A high solution concentration of the feed also resulted in the formation of comparably rougher surfaces than a low feed concentration. Spray-dried particles showed a volume-weighted mean particle size of 71.4-90.0 mu m and narrow particle size distributions. The mean particle size was influenced by the atomizer rotation speed and feed concentration. Higher rotation speeds and lower feed concentrations resulted in smaller particles. Breaking strength of the dried particles was significantly influenced by gas heater temperature and feed rate. High gas heater temperatures increased the breaking strength, whereas high feed rates decreased it. No influence of the process parameters on the polymorphism was observed. All products were crystalline, consisting of at least 96.9% of mannitol crystal modification I.

The influence of the atomization method on the product homogeneity in spray drying is discussed. For identical drying histories at individual particles, a narrow drop size distribution has to be achieved in order to produce a homogeneous powder. Spray drying experiments with aqueous solutions of polyvinylpyrrolidon and D-Mannitol were carried out. For generation of narrow distributed droplets a laminar operated rotary atomizer is applied. Homogeneous particle properties of the powders were achieved. However, this kind of atomization requires special drying gas distribution. A possible geometry for a proper heating gas distribution is presented.

During microencapsulation of sensitive (food) ingre dients by spray drying, one important step is the s pray drying process itself, which affects the emulsion droplet size distribution, the emulsion stability with rega rd to the oil droplet size as well as the structural integrity of the interface. The latter has a strong impact on t he encapsulation efficiency and the physical stability of reconstitu ted emulsions. By interfacial engineering the barri er properties and the packing density at the oil/water (o/w) inte rface can be modified. The interface can be enginee red by e.g. layer-by-layer-technology that involves sequential layering of polymers at the o/w-interface of an emu lsion via electrostatic interactions. By that means so-called multilayer emulsions can be obtained. Studies on t he characterization of these multilayer emulsions in relatio n t the spray drying process, especially with resp ect to the type of atomization and the drying behavior are lacking a d literature on the oxidative stability of spraydried multilayer emulsions is scarce. Scope Aim of the present study was to investigate the imp act of atomization and drying on the functionality of emulsions with a modified o/w interface consisting of b eta-lactoglobulin and pectins with varying degree o f methylation. Experimental Approach Beta-lactoglobulin and pectin (low and high methyla ted) were used for preparation of single and multil ayeremulsions containing fish oil. Electrostatic intera ctions were analyzed via zeta potential measurement s. Elasticity of emulsion interfaces was analyzed by droplet shap e analysis. The single droplet drying behavior was characterized by acoustic levitation. Spray droplet and oil droplet size distribution were measured by laser di ff action after two-fluid-nozzle and rotary atomization at differen t energy inputs. Spray drying was carried out at 18 0/70 °C inlet/outlet temperature. The morphology of the par ticles was analyzed by scanning electron microscopy . The oxidative stability of the fish oil was monitored v ia hydroperoxide and propanal content. Major results The single droplet drying behavior of the different ly stabilized emulsions was similar as examined by levitation. With regard to the atomization process, the emulsio n pray droplet size generally decreased with incre asing energy input to the atomizer. In two-fluid nozzle ato mization but not in rotary atomization, the spray d roplet size distribution was markedly influenced by the differe nc s in emulsion viscosity. The spray droplet size distribution was narrower with rotary atomization compared with two-fluid nozzle atomization. The oil droplet size of the emulsions was only slightly affected by the differe nt nergy inputs during atomization. However, in th e reconstituted state, the oil droplet size was higher than i n the original emulsions, which can be attributed t o coalescence. The oxidative stability of the oil was influenced b y oth the physical state of the emulsions and the diff rent constituents at the o/w-interface. For instance, in th e liquid state the oxidative stability was higher i n the original emulsions when compared to the reconstituted emulsi ons. Furthermore, the oxidative stability was affec ted by the type of pectin and thus the intensity of the oi l droplet charge. It can be assumed that in liquid an spray-dried emulsions, not only the particle charge but also th e constitution of the interface itself influences t he oxidative stability of encapsulated oil. * Corresponding author: yvonne.serfert@tu-berlin.de

Bei der Spruhtrocknung von Losungen oder dispersen Systemen ist eine enge Tropfengrosenverteilung des Zerstaubers notwendig, um ein hochwertiges Feststoffprodukt mit enger Korngrosenverteilung zu erzielen. Enge Tropfengrosenverteilungen konnen durch Flussigkeitsfadenzerfall an Rotationszerstaubern erzielt werden. In Zerstaubungsversuchen auserhalb des Spruhtrockners, insbesondere an Brausen, werden enger verteilte Tropfengrosen beobachtet als im Spruhtrockner. Es wird gezeigt, dass dies mit der Gas/Flussigkeits-Wechselwirkung zwischen den Flussigkeitsfaden und dem Heizgas im Spruhtrockner erklart werden kann. Die Art und Auspragung der Gas/Flussigkeitswechselwirkung der Faden wird analysiert und es wird gezeigt, dass eine relative Anstromung der Faden quer zu deren Langsachse vorliegt. Diese relative Queranstromung ist nicht intensiv genug, um zu einer unmittelbaren Zerstaubung der Faden zu fuhren, ist aber stark genug, um zu einer sichtbaren Deformation und zu einer Storung des Fadenzerfalls zu fuhren. Ziel der vorliegenden Arbeit ist die quantitative Charakterisierung des Einflusses dieser Queranstromung. Daruber hinaus wird eine Optimierungsstrategie entwickelt, die eine geringstmogliche Storung des Fadenzerfalls durch die Gas-Flussigkeits- Wechselwirkung im Spruhtrockner erlaubt. Hieraus wird ein Konzept entwickelt, das eine geeignete Heisgasfuhrung im Spruhtrockner vorsieht. Es werden zwei Typen von Heisgasverteilern vorgestellt, die das Heisgas so in den Trockner einleiten, dass die resultierende Gasstromung dem entwickelten Konzept genugt. Die beiden Gasverteilertypen unterscheiden sich in ihrem apparativen Aufwand aber auch im erzielbaren Vorteil bzgl. der Tropfen- und Korngrosenverteilung. Die verwendeten Methoden zur quantitativen Untersuchung des Fadenzerfalls unter Queranstromung bzw. zur apparativen Umsetzung des Optimierungskonzepts kombinieren das klassisch ingenieurwissenschaftliche Werkzeug der Dimensionsanalyse und der Modelltheorie mit numerischer Stromungssimulation. Modellversuche zum Zerfall angestromter Flussigkeitsfaden im Schwerefeld zeigen, dass niedrigste Gas- Relativgeschwindigkeiten der Flussigkeitsfaden - auch im Spruhtrockner – zu einem optimalen Zerstaubungsergebnis fuhren. Im Rahmen der Entwicklung des optimierten Heisgasverteilers wird gezeigt, dass die Ergebnisse der Modellversuche weitgehend auf die Rotationszerstaubung ubertragbar sind. Daruber hinaus stellen die Ergebnisse der Modellversuche eine neue und breite Datenbasis zum Zerfall quer angestromter Flussigkeitsstrahlen dar.%%%%In spray drying processes narrow droplet-size-distributions have to be ensured, in order to achieve a high quality product, exhibiting a narrow particle-size-distribution (PSD). Narrow distributed drop sizes can be produced by rotary atomizers, operated in the regime of laminar thread break-up. However, in atomization experiments outside the spray dryer even narrower drop-size-distributions are observed, compared to the PSD of the spray dried product. This can be explained by the aerodynamic interaction…

Rotary atomizers operated in the regime of laminar thread disintegration can be used for the production of sprays with narrow distributed droplet sizes. The liquid threads formed are attenuated due to centrifugal acceleration and small drop sizes can be achieved, compared to the thread detachment diameter. LAMROT atomizers can hold the desired break-up mode for an extensive range of liquid feed rates and revolution rates. This kind of rotary atomizer has a low plugging tendency and can be designed according to the principles described in [1]. For process design the mean drop size d50,3 of the spray and the droplet span, representing the width of the droplet size distribution (DSD), have to be known. Empirical correlations are frequently used for the calculation of these parameters. However, such kind of correlations are often restricted to a specific atomizer geometry, to specific operating conditions respectively. Therefore similarity trials were carried out, covering a wide range of typical operating conditions for liquid thread break-up at rotary atomizers. The main influences on the thread break-up, like e.g. the gas-liquid interaction during thread break-up, were identified and separately varied. It is shown that the results of the similarity experiments can be used for elaborating empirical correlations for mean drop size and span, that are also valid for thread break-up at rotary atomizers. These correlations can be applied to the design of spray processes including spiraling thread disintegration. As an example the design of a spray drying process including a LAMROT atomizer will be discussed.

Aim of the present study was to investigate the imp act of atomization and drying on the functionality of emulsions with an oil/water-interface (o/w-interface) c onsisting of beta-lactoglobulin (single layer emuls ion) and sequentially adsorbed pectins with varying degree of methylation at pH<pI (bilayer emulsions). Thus, the emulsion systems were characterized with respect to their be havior during atomization, their drying behavior in single droplet experiments and the oxidative stability of the dispersed phase (fish oil) during storage of li quid and spray-dried single and bilayer emulsions. The o/w-interface of the emulsions was predominantl y elastic, although the elasticity was higher in si gle layer emulsions compared to bilayer emulsions. The drying behavior of the different emulsions duri ng levitation of single droplets was similar. Regarding the atomization process, the emulsion spray droplet siz generally decreased with increasing energy input irrespective of the type of atomizer. With rotary atomization, the spray droplet size distribution of the different emulsion s was similar. The oxidative stability of the oil w as influenced by both the physical state of the emulsions and the diff rent constituents at the o/w-interface. In th e liquid state, the oxidative stability was higher in the original emulsions when compared to the reconstituted emulsi ons. The differences in oxidative stability in the spray-dri ed emulsions can partly be attributed to the microe ncapsulation efficiency, but also the physical characteristics o f the o/w-interface, which needs to be investigated in more detail.

The aim of this work was to study the performance of mannitol carrier particles of tailored surface roughness in dry powder inhaler formulations. Carrier particles of different surface roughness were prepared by spray drying of aqueous mannitol solutions at different outlet temperatures at a pilot-scale spray dryer. However, the carrier particles did not only change in surface roughness but also in shape. This is why the impact of carrier shape on the performance of carrier based dry powder inhalates was evaluated also. The highest fine particle fraction (FPF), that is the amount of active pharmaceutical substance, delivered to the deep lung, is achieved when using rough, spherical carrier particles (FPF=29.23 ± 4.73%, mean arithmetic average surface roughness (mean R(a))=140.33 ± 27.75 nm, aspect ratio=0.925). A decrease of surface roughness (mean R(a)=88.73 ± 22.25 nm) leads to lower FPFs (FPF=14.62 ± 1.18%, aspect ratio=0.918). The FPF further decreases when irregular shaped particles are used. For those particles, the micronized active accumulates within the cavities of the carrier surface during the preparation of the powder mixtures. Upon inhalation, the cavities may protect the active from being detached from the carrier.

Aim of the present study was to characterize the pr ocess of atomization and drying of layer-by-layer emulsions containing lecithin (single layer emulsio n) and lecithin/chitosan (multilayer emulsion) and the oxidative stability of the spray-dried emulsions du ring storage. For this purpose, the analysis of the emulsion spray droplet size during atomization by two differ ent atomization devices, i.e. two-fluid nozzle and rotary atomizer, was carried out to identify suitable proc ess parameters. The drying behaviour of single laye r nd multilayer emulsions was investigated by single-dro p drying via calculation of the mass transfer durin g acoustic levitation. In spray-dried emulsions, the oxidative stability in the single layer emulsions w as higher than in the multilayer emulsion. This was partly a ttributed to a lower microencapsulation efficiency in the spray-dried multilayer emulsion compared to the spr ay-dried single layer emulsion. Furthermore, it cou ld be shown, that excess chitosan in the bulk carrier mat rix ffects the free volume elements and thus oxyge n diffusion.

The motivation for this study was to find an adequate substitute for lactose as carrier in dry powder inhalers and to overcome some drawbacks inherent to lactose. Mannitol appears to be the ideal replacement of lactose because it lacks the risk of transmitting the transmissible spongiform encephalopathy, mannitol does not carry reducing groups, that may cause chemical interactions with drugs such as proteins, and is highly crystalline even upon spray drying. Spray drying in turn is a dedicated technology to prepare carrier particles for dry powder inhalers. Typically spherical particles are generated constituting comparable interparticle forces to every drug particle attached to their surface. This study shows, that mannitol particles of different surface roughness can be prepared by spray drying at different outlet temperatures, providing the opportunity of tailoring the contact area respectively the interparticle interactions between the drug and the carrier. The emergence of different surface roughness was attributed to different crystallization mechanisms. Surface roughness was quantified by confocal laser-scanning microscopy. Quantitative Raman spectroscopy revealed, that the spray dried products consist mainly of the thermodynamically stable modification I° besides small amounts (5 to 15%) of the metastable modification II, irrespective of the drying temperature and the crystallization mechanisms taking place. This renders mannitol a most suitable substitute of lactose for the use in dry powder inhalers.