Flow Visualisation and Instantaneous Velocity Measurements of Spray Dryer Gas and Spray Flows Using Particle Image Velocimetry

Stafford, Robert A.; Fauroux, O.; Glass, Donald

doi:10.1080/07373939708917316

Cited by 5 publications

(7 citation statements)

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“…The presence of the outlet air ducts at the top of the chamber means dry fine powder is recirculated to the top of the chamber to interact with the atomiser cloud, thus increasing agglomeration. This mechanism is known as spontaneous secondary agglomeration (Westergaard, 2003). This paper examines the flow patterns in an industrial spray dryer used for milk powder production.…”

Section: Figure 1: Schematic Of Modern Milk Powder Plantmentioning

confidence: 99%

“…The offset outlet pipe at the base of the chamber caused the central jet to be significantly off the dryer axis. However, like the simulations of Straatsma et al (1999), there was no internal fluid bed flow nor any validation attempted.…”

Section: Figure 1: Schematic Of Modern Milk Powder Plantmentioning

confidence: 99%

“…Also, industrial scale simulations that include transient particle tracking, hindered drying and wall deposition are extremely expensive computationally (Fletcher et al, 2003). Straatsma et al (1999) developed a 2D drying simulation model to investigate two industrial spray dryers (heights 14 and 17 m) used for milk powder production. The air outlets in both cases were at the top of the chamber but no internal fluid bed was included.…”

Section: Figure 1: Schematic Of Modern Milk Powder Plantmentioning

confidence: 99%

“…Modern spray dryers ( Figure 1) are two stage dryers where internal fluidised beds at the base of the chamber provide the second stage of drying. This allows for lower outlet air temperatures because of the evaporation occurring in the fluid bed, thus improving dryer efficiency and making the operation even more suitable for drying heat sensitive materials (Westergaard, 2003).…”

Section: Introductionmentioning

confidence: 99%

“…Numerous CFD simulations on spray dryers have been published (Fletcher et al, 2003, Guo et al, 2003, Harvie et al, 2002, Kieviet et al, 1997, Langrish, 1993, LeBarbier et al, 2001, Oakley and Bahu, 1990, Stafford et al, 1996, Straatsma et al, 1999. Stafford et al (1996) used particle image velocimetry (PIV) to measure the velocity field in a small spray dryer with pressure nozzle atomisation. They observed for the case of no inlet swirl, an off centre jet and no symmetrical recirculation zone.…”

Section: Introductionmentioning

confidence: 99%

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Air flow patterns in an industrial milk powder spray dryer

Gabites

Abrahamson

Winchester

2010

Chemical Engineering Research and Design

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The air flow patterns in an industrial milk powder spray dryer were investigated. Isothermal three-dimensional transient simulations were carried out using the commercial CFD code CFX10.0. The Shear Stress Transport (SST) turbulence model was implemented to model the effects of turbulence.These simulations differ from previously published studies of spray dryer air flows in that they include features found in industrial scale plant. First, they include a second inlet air stream through the internal fluid bed at the bottom of the drying chamber. Second, the two outlet ducts are located near the top rather than the bottom of the dryer, which has been the case in most previous studies.It was found that the main air jet oscillated and precessed about the central axis. In turn, the recirculation zones between the main jet and the chamber walls fluctuated in size relative to the movement of the jet.Validation was achieved by observing the oscillation of the main air jet of a large dryer visualised by tell-tail tufts attached to a central pole.

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Section: Figure 1: Schematic Of Modern Milk Powder Plantmentioning

confidence: 99%

Section: Figure 1: Schematic Of Modern Milk Powder Plantmentioning

confidence: 99%

Section: Figure 1: Schematic Of Modern Milk Powder Plantmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Air flow patterns in an industrial milk powder spray dryer

Gabites

Abrahamson

Winchester

2010

Chemical Engineering Research and Design

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An experimental study of dynamic jet behaviour in a scaled cold flow spray dryer model using PIV

et al. 2014

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Research on the dynamic flow behaviour in spray dryers has a long history. Interest in describing these flows originates from problems like roof and wall fouling. The aim of the present study is to experimentally investigate the dynamic jet behaviour and turbulent flow in a scaled-down cold flow model of a spray dryer in order to better understand and optimize spray drying units. Dynamic jet behaviour and turbulent flow features (i.e., RMS velocities) were studied by particle image velocimetry (PIV) using water as the continuous phase. To obtain more insight in the jet dynamics, we analyzed the turning point, the width and shape, and the velocity profiles of the turbulent jet at different heights and the turbulence characteristics. We found that at higher Reynolds numbers, the jet penetrates further along the downward direction with a time-averaged profile which is symmetric at the centre. In addition, we investigated the effect of the expansion ratio via proper orthogonal decomposition (POD). Outcomes of different characteristics of the dynamic jet, like steady, transient, regular, and complex precession, can be collapsed by proper scaling. These results can be used for validation of computational fluid dynamics simulations and facilitate the design (identification of jet operation boundaries) of new spray dryer configurations.

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