Development of a zone flow model for the confined impeller stirred tank (CIST) based on mean velocity and turbulence measurements

Komrakova, Alexandra; Liu, Z.; Machado, Márcio B.; Kresta, Suzanne M.

doi:10.1016/j.cherd.2017.07.025

Cited by 16 publications

(12 citation statements)

References 67 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…19 The geometry used in this work is a confined-impeller stirred tank (CIST). 20,21 The CIST is a lab-scale vessel; it holds approximately 1 L of fluid. The tank height is three times its diameter to accommodate more impellers (5−6) and to facilitate the study of settling.…”

Section: Introductionmentioning

confidence: 99%

“…Compared to a bench-scale stirred tank, the CIST provides a more uniform energy dissipation field, allowing for fully turbulent flow at lower impeller speeds and Reynolds numbers. 20 Komrakova et al 21 found that most of the vessel is in active circulation: only 5.45% is inactive, compared to 33% in a stirred tank. 22 Several studies have used the CIST to study the separation of water from bitumen froth 23 and diluted bitumen.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Dewatering of Poor-Quality Bitumen Froth: Induction Time and Mixing Effects

Saraka

Machado

et al. 2018

Energy Fuels

View full text Add to dashboard Cite

The impact of mixing conditions on the removal of water and solids from high-water, poor-quality bitumen froth was explored. Naphtha diluent and a demulsifier were added to improve removal of water and solids from bitumen froth. The mixing and subsequent settling of this system were carried out in the confined-impeller stirred tank, a lab-scale mixing test vessel with well-characterized, relatively uniform mixing conditions. A protocol for finding the proper demulsifier dosage at which to study mixing effects was applied successfully. High mixing energy J and the predilution of demulsifier (characterized by its injection concentration IC) improved dewatering and solids removal performance, agreeing with earlier studies in diluted bitumen and bitumen froth of higher quality (Laplante et al. Fuel Process. Technol. 2015, 138, 361–367; Arora, N. Mechanisms of Aggregation and Separation of Water and Solids from Bitumen Froth Using Cluster Size Distribution, 2016). An unexpected finding was that dewatering was significantly delayed in poor-quality froth: it was not detectable until up to 45 min in some cases. This induction time was replicated and was clearly impacted by changes in the mixing conditions.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dewatering of Poor-Quality Bitumen Froth: Induction Time and Mixing Effects

Saraka

Machado

et al. 2018

Energy Fuels

View full text Add to dashboard Cite

show abstract

“…The experiments were carried out in a jacketed confined impeller stirred tank (CIST), as shown in Figure . This is a lab‐scale mixing test vessel, designed to provide well‐characterized and relatively uniform turbulent mixing conditions at bench scale as reported by Komrakova et al The CIST has a volume of ∼1 L, a diameter (T) of 76 mm, and a liquid height (H) of 228 mm . The experimental setup and procedure are described by Saraka .…”

Section: Methodsmentioning

confidence: 99%

“…Four rectangular baffles with a width W b = T/12 were evenly spaced around the periphery of the tank. The FBRM probe was placed in the return stream of the top impeller as shown in Figure . This location was chosen to provide an angle of 30–60° between the bulk flow and the FBRM probe window for several impeller geometries, including the Rushton impellers shown in the diagrams.…”

Section: Methodsmentioning

confidence: 99%

Effective sapphire repellency treatment to reduce fouling of a focused beam reflectance measurement (FBRM) probe in bituminous systems

et al. 2019

View full text Add to dashboard Cite

The use of a focused beam reflectance measurement (FBRM) probe to track the chord length distribution dynamics in a bituminous system can be very challenging. Material coats the sapphire window of the probe and the quality of the data is compromised. The fouling index is a parameter used to assess the quality of the FBRM data. It is provided by the software and is the percentage similarity between two consecutive scans of the instrument, indicating how much of the reading has not changed due to material that is stuck to the optical window. When the FBRM was used in bitumen froth, the fouling index was higher than 90 %. In this work the significant reduction in fouling achieved with a sapphire repellency treatment is presented. The reduction in fouling was sufficient to detect broad trends in the FBRM data that will be used in future studies but was not sufficient to ensure quantitative measurement of the chord length distribution.

show abstract

“…The confined impeller stirred tank (CIST) is a 1‐L bench‐scale mixing test cell. It was designed to replicate local mixing conditions particularly at the feed point for industrial mixing problems , . The CIST is filled with five or six impellers to provide uniform turbulence as illustrated in Fig.…”

Section: Introductionmentioning

confidence: 99%

Blend Time Measurement in the Confined Impeller Stirred Tank

et al. 2019

View full text Add to dashboard Cite

An image processing technique is applied to measure the blend time in a confined impeller stirred tank (CIST). An acid-base reaction is used to track mixing. The blend time is defined as the time taken to 95 % or 99 % of the pixels change color from purple to yellow. Six sets of impellers are employed: Rushtons, A310s, pitched-blade turbines (PBTs; three different combinations of up-and downpumping), and Intermigs. Variation of the Reynolds number Re showed that the blend time becomes shorter with increasing Re and longer with higher viscosity. As Re drops below 225, compartmentalization becomes apparent and the decolorization percentage increases suddenly when the acid reaches each communication point between the impellers.

show abstract

Development of a zone flow model for the confined impeller stirred tank (CIST) based on mean velocity and turbulence measurements

Cited by 16 publications

References 67 publications

Dewatering of Poor-Quality Bitumen Froth: Induction Time and Mixing Effects

Dewatering of Poor-Quality Bitumen Froth: Induction Time and Mixing Effects

Effective sapphire repellency treatment to reduce fouling of a focused beam reflectance measurement (FBRM) probe in bituminous systems

Blend Time Measurement in the Confined Impeller Stirred Tank

Contact Info

Product

Resources

About