Importance of CIP velocity
Special Symposium - Innovations in Food Technology (LMC Congress)
Hygiene, Hygienic Design & Unit Operations (Food-5a)
Keywords: Hygienic design, CFD, CIP, flow velocity
The flow of detergent is an important factor in the cleaning of closed processing equipment. The liquid generates the force acting on the soil on the surface and acts as carrier for the chemicals and the heat. Typically, cleaning is performed at constant flow rates throughout the system and the cleaning time decided based on the criteria; the area most difficult to clean must be cleaned at the end of the cleaning. The most difficult to clean areas are dead-ends and crevices in the geometry (resulting in recirculation zones) and shadow zones (resulting in stagnation points). In and around these features are low wall shear stress and fluid exchange, which both reduce the cleaning efficiency (Jensen and Friis, 2005).
Industry often asks if changing the velocity during cleaning-in-place (CIP) can reduce the cleaning time. This paper focuses on practical and numerical experiments on cleaning of an upstand with different flow rates (and pulsation) and flow in a spehrical shaped valve house. It was shown that the pulsation only has minor effect on removal of the soil used, but more interestingly, that the areas always difficult to clean is located in the exact same positions independent on flow rate and pulsations. Steady state and transient computational fluid dynamics simulations are used to generate information about the flow patterns, so these phenomena can be explained. The reason for the idea of changing the flow rate is to change the size of recirculation zones and the position of stagnation points to improve cleaning effects.
Presented Thursday 20, 09:50 to 10:05, in session Hygiene, Hygienic Design & Unit Operations (Food-5a).
