Microgranulation of fine powders by a novel rotating fluidized bed granulator

Watano, Satoru; Imada, Yasushi; Hamada, Kenji; Wakamatsu, Yoshihiro; Tanabe, Yoshiaki; Davé, Rajesh N.; Pfeffer, Robert

doi:10.1016/s0032-5910(03)00007-x

Cited by 67 publications

(41 citation statements)

References 8 publications

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“…Figure 5 shows a schematic diagram of a rotating fluidized bed coater. [2][3][4] A rotating fluidized bed coater consists of a plenum chamber and a porous cylindrical air distributor (ID 0.4 mϫD 0.1 m) made of stainless sintered mesh with 20 mm openings. The horizontal cylinder (air distributor) rotates around its axis of symmetry inside the plenum chamber.…”

Section: Methodsmentioning

confidence: 99%

“…Equation of continuity (1) Equations of motion r-direction (2) q-direction (3) z-direction (4) where, e, u, P are the voidage, the gas velocity, the gas pressure, and r f and f i are the gas density and the volumetric interaction forces between particle and fluid. The f i in Eqs.…”

Section: Numerical Modelmentioning

confidence: 99%

“…[2][3][4] Since the RFB can impart high centrifugal force and drug force to particles, which are larger than the cohesive forces, the RFB enables fine particles to fluidize uniformly. We have already reported that wet granulation 2) and film coating 3,4) of fine particles (group C in the Geldart's classification) could be smoothly conducted in a RFB, in which any conventional fluidization techniques have been impossible to do. However, the particle fluidization behaviors in a RFB are very complicated, and mechanisms of film coating process have not been well studied yet.…”

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confidence: 99%

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Numerical Simulation of Film Coating Process in a Novel Rotating Fluidized Bed

Nakamura

Iwasaki

Watano

2006

CHEMICAL & PHARMACEUTICAL BULLETIN

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Particle coating process has been widely employed in many industries, such as food, agriculture, cosmetic and pharmaceutical industries, in order to produce functional materials. Among many types of particle coating system, fluidized bed is one of the most promising techniques because of its advantages of high heat transfer, temperature homogeneity, high mixing performance, flowability of particulate materials, and availability of multilayer coating capability.Recently, fine particles, having size range between several micrometers and nanometers, have become major interest in many industries. In the pharmaceutical industry, fine particles have been expected for novel drug delivery systems, such as asthma therapy by inhalation or cancer therapy by transcatheter arterial embolization. However, according to the Geldart's classification, 1) it is very difficult to fluidize fine particles in group C having diameters less than 20 mm, because of the strong cohesive forces between fine particles. Therefore, a reliable technique for fluidization of fine particles and giving tailored functions to them is strongly required. So far, we have developed a novel rotating fluidized bed (RFB) in order to fluidize fine powders. [2][3][4] Since the RFB can impart high centrifugal force and drug force to particles, which are larger than the cohesive forces, the RFB enables fine particles to fluidize uniformly. We have already reported that wet granulation 2) and film coating 3,4) of fine particles (group C in the Geldart's classification) could be smoothly conducted in a RFB, in which any conventional fluidization techniques have been impossible to do. However, the particle fluidization behaviors in a RFB are very complicated, and mechanisms of film coating process have not been well studied yet. From the viewpoint of "Quality by Design (QBD)," it is very important to propose a model for film coating process and analyze the relationship between the operating conditions and quality of products, such as uniformity of coated material, in a RFB.There are some studies on numerical simulation of film coating process in a fluidized bed, such as a population balance model in a conventional fluidized bed 5) and Monte Carlo simulation in a tumbling fluidized bed. 6) However, these models are very complicated and calculation results strongly depend on the model parameters. By contrast, a DEM-CFD coupling model 7) is one of the most useful numerical models of fluidized bed. In this model, individual particle motion and fluid motion are calculated by a discrete element method (DEM) and a numerical method of computational fluid dynamics (CFD). In the DEM simulation, individual particle motion can be calculated based on 'first principle'; integrating the Newton's second law for individual particle, allowing for external forces, such as contact forces, drag force and etc., acting on each particle. Therefore, it is expected that film coating process can be well simulated by using a DEM-CFD coupling model. However, there is no report on numerical sim...

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Section: Methodsmentioning

confidence: 99%

Section: Numerical Modelmentioning

confidence: 99%

mentioning

confidence: 99%

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Numerical Simulation of Film Coating Process in a Novel Rotating Fluidized Bed

Nakamura

Iwasaki

Watano

2006

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…The moving geometry complicates sealing and continuous feeding and removal of solids and introduces additional challenges related to vibrations. Nevertheless, rotating fluidized beds have been shown successful in removing the limitations of gravitational fluidized beds and, for example, allow the fluidization of micro-and nano-particles [Qian et al, 2001;Watano et al, 2003;Quevedo et al, 2005]. In this chapter, a novel technology is focused on that allows taking advantage of high-G operation in a static geometry.…”

Section: The Limitations Of Conventional Fluidized Bedsmentioning

confidence: 99%

Gas-Solid Heat and Mass Transfer Intensification in Rotating Fluidized Beds in a Static Geometry

Wilde¹

2011

Heat Transfer - Theoretical Analysis, Experimental Investigations and Industrial Systems

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“…The air flows radially inward through the air-distributor and the forces on the grain (Fig. 1) are balanced by the airflow (drag force and buoyancy force) and the centrifugal force (Watanoa et al, 2003;Elmi et al, 2009;Opafunso et al, 2009). The variable defined r is radius of an air-distributor (m) and ω is an angular velocity (rad sec −1 ).…”

Section: Introductionmentioning

confidence: 99%

The Drying Kinetics of Chilies using a Rotating Fluidized Bed Technique

Dongbang¹

2010

American Journal of Applied Sciences

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Problem statements:The present study investigates experimentally the drying of chilies (Capsicum annuum L.) with rotating fluidized bed technique and the biological properties: capsaicin content, moisture diffusivity and activation energy. Approach: The drying experiment was conducted at the drying air temperatures ranged 70-120°C and the drying air velocity was fixed at 1.8 m sec −1 , while the layer's height was fixed at 4 ± 0.5 cm. The chilies were dried starting 350 ± 5%db down to 10 ± 1%db. Results: The drying time requested to dry chilies ranged 69-257 min. The average capsaicin content of dried chilies was decreased starting 2725.4 down to 1617.4 ppm. The effective diffusivity and activation energy were also described. Conclusion: Drying air temperature was significant factor on the decreasing of moisture content, capsaicin content and redness of dried chilies. All samples can be marketable.

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Microgranulation of fine powders by a novel rotating fluidized bed granulator

Cited by 67 publications

References 8 publications

Numerical Simulation of Film Coating Process in a Novel Rotating Fluidized Bed

Numerical Simulation of Film Coating Process in a Novel Rotating Fluidized Bed

Gas-Solid Heat and Mass Transfer Intensification in Rotating Fluidized Beds in a Static Geometry

The Drying Kinetics of Chilies using a Rotating Fluidized Bed Technique

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