Mechanism and control of electrification in pneumatic conveying of powders

Watano, Satoru

doi:10.1016/j.ces.2005.05.008

Cited by 42 publications

(20 citation statements)

References 8 publications

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“…New approaches based on Distinct Element Method and combined with Computational Fluid Dynamics are emerging which are fully predictive based on single particle characteristics, e.g. Watano (2006) and Lim et al (2006).…”

Section: Contact Potential Differencementioning

confidence: 99%

Triboelectrification of pharmaceutical powders by particle impact

Watanabe

Ghadiri

Matsuyama

et al. 2007

International Journal of Pharmaceutics

105

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Pharmaceutical powders are very prone to electrostatic charging by colliding and sliding contacts with walls and other particles. In pharmaceutical formulation processes, particle charging is often a nuisance and can cause problems in the manufacture of products, such as affecting powder flow, and reducing fill and dose uniformity. For a fundamental understanding of the powder triboelectrification, it is essential to study charge transfer due to a single contact of a particle with a target plane under well-defined physical, mechanical and electrical conditions. In this study, charge transfer due to a single impact of a particle against a stainless steel target was measured for alpha-lactose monohydrate, aspirin, sugar granules and ethylcellulose. The amount of transferred charge is expressed as a function of impact velocity and impact angle as well as the initial charge. The maximum contact area during impact between a particle and a target plane is estimated by an elastic-plastic deformation model. It is found that the transferred charge is a linear function of the contact area. For a given material, there is an initial particle charge for which no charge transfer occurs due to impact. This is found to be independent of impact velocity and angle, and is hence viewed as a characteristic property, which is related to the contact potential difference and tribo-electric series of the sample powders.

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Section: Contact Potential Differencementioning

confidence: 99%

Triboelectrification of pharmaceutical powders by particle impact

Watanabe

Ghadiri

Matsuyama

et al. 2007

International Journal of Pharmaceutics

105

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“…The mechanism of hydrodynamically driven segregation could be deliberately and fully suppressed by choosing appropriate closures for their particle-phase pressure. Watano et al (2003) and Watano (2006) proposed a model for analysis and prediction of particle electrification and showed that the electrification of particles during pneumatic conveying depended on the number of particle collisions against the pipe wall and the normal component of the impact velocities. More recently, computer simulations of pneumatic conveying carried out by Lim et al (2006) using the discrete element method (DEM) and computational fluid dynamics (CFD) without consideration of electrostatic effects showed that such effects were unnecessary for the formation of most flow regimes observed by Rao et al (2001) and Zhu et al (2003) experimentally.…”

Section: Introductionmentioning

confidence: 99%

Effects of an electrostatic field in pneumatic conveying of granular materials through inclined and vertical pipes

Lim

Zhang

Wang

2006

Chemical Engineering Science

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“…The work function of a powder depends on its physical and chemical properties including environmental conditions (Yurteri et al, 2002;Matsusaka and Masuda. 2003;Watano, 2006;He et al, 2014;Karner et al, 2014;.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of a new dispersion technique for assessing triboelectric charging of powders

Zafar

Alfano

Ghadiri

2018

International Journal of Pharmaceutics

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In a number of applications, especially in pharmaceutical drug development, there is often a very small powder quantity available for evaluating the manufacturability of new drugs. However, it is highly desirable to be able to quickly evaluate processing issues, and where possible using the smallest powder quantity. In the present work, a proprietary commercial powder dispersion device (the disperser of Malvern© Morphologi G3) is adapted to evaluate the triboelectric charging tendency. A very small powder quantity (as small as 0.1 mg) is dispersed by a pressure pulse of compressed gas such as air or nitrogen. This causes the particles to become air borne and collide with the containing walls, resulting in dispersion and leading to triboelectric charge transfer between the particles and the walls. In this work, the charging propensity of a number of materials is evaluated and the effect of particle surface functional groups on the tribo-electric charge transfer is analysed. Model materials with a well-defined shape (glass ballotini) but with different silane groups deposited on their surfaces as well as a number of organic crystalline particles (such as aspirin, α-lactose monohydrate and paracetamol) are tested. Following dispersion the particles move immediately to a Faraday cup placed directly underneath the disperser. Therefore, particle charge is measured with no decay. The method can differentiate charging of different polymorphs of the same material, different silane groups on the surfaces of glass ballotini and different crystal morphologies obtained from crystallisation from various solvents.

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Mechanism and control of electrification in pneumatic conveying of powders

Cited by 42 publications

References 8 publications

Triboelectrification of pharmaceutical powders by particle impact

Triboelectrification of pharmaceutical powders by particle impact

Effects of an electrostatic field in pneumatic conveying of granular materials through inclined and vertical pipes

Evaluation of a new dispersion technique for assessing triboelectric charging of powders

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