Investigation of fluid mechanical removal in the cleaning process

Palabiyik, Ibrahim (2013). Investigation of fluid mechanical removal in the cleaning process. University of Birmingham. Ph.D.

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The cleaning of pipework from fluids of high viscosity is a significant problem in many food and personal care industries which can cause considerable economic and environmental impact. Three stages are identified in the cleaning of straight pipes; (i) a short core removal stage of product recovery, before water breaks through the filled pipe, (ii) the 1st cleaning stage (film removal stage) when there is a continuous wavy annular film on the wall, and (iii) the 2nd cleaning stage (patch removal stage) in which the material is present as patches on the wall.
The product recovery stage is found to influence the overall cleaning process. Conducting product recovery at low temperatures and high flow rates cause the formation of a wavy wall layer which leads to more rapid subsequent removal. A two step CIP protocol is proposed to decrease the environmental impact of cleaning of a viscoelastic material (toothpaste) from pipework. Applying cold water in the 1st cleaning stage and hot water in the 2nd cleaning stage results in 40 % energy saving without affecting the cleaning performance significantly compared to traditional CIP protocols used in plants. Yield stress of deposits is the key effect on the cleaning of deposits. A new dimensionless number is explored. It is physically a ratio of flow energy to the yield stress of a deposit. It has collapsed cleaning time data onto a one curve for different deposits cleaned at different velocities. It can be used to predict cleaning times of deposits or identify the governing cleaning mechanisms in cleaning.
It is found that the magnitude of pressure loss in flow can be used to quantify the flow and turbulence effect on cleaning and scale up lab scale data. The results show that although fluid mechanical removal is a complex process, cleaning time of deposits can be predicted by knowing its rheology and fluid mechanical parameters of cleaning fluid.

Type of Work: Thesis (Doctorates > Ph.D.)
Award Type: Doctorates > Ph.D.
College/Faculty: Colleges (2008 onwards) > College of Engineering & Physical Sciences
School or Department: School of Chemical Engineering
Funders: None/not applicable
Subjects: T Technology > T Technology (General)
T Technology > TP Chemical technology


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