Adel Fickak (PhD student, Laboratory Manager) tel: +61-3-99059467 e-mail: adel.fickak@eng.monash.edu.au Room 207, Building 36 Engineering

Cleaning In Place 'CIP' in Dairy Plant

Cleaning-in-Place (CIP) is employed in Oil Refineries and food industry so that the processing equipments do not need to be dissembled when they are cleaned.
A considerable amount of research has been conducted in recent years to seek ways of improving the CIP procedure.
Both the chemical reactions and fluid shear play roles in the removal of fouling deposit but the effect of chemical reaction is one that is of the key importance.
The dairy industry in particular suffers from problems associated with cleaning production machinery including heat exchangers.

In the dairy industry, thermal processing is an energy intensive process since every product is heated at least once.
Processing over 13 billion liters of milk every year in New Zealand (Fonterra 2004) means the efficiency of the heating process is of paramount importance.
Fouling (Deposits) of heat exchangers is a serious problem as it reduces heat transfer and increases pressure drop. As a result of fouling, there is a possibility of deterioration in product quality since the process fluid cannot be heated up to the required temperature (say for pasteurization or sterilization). The deposits dislodged by the flowing fluid can also cause contamination.
Fouling related costs are: additional energy, lost productivity, additional equipment, manpower, chemicals, and environmental impact.

Generally milk fouling is so rapid that heat exchangers need to be cleaned every day to maintain production capability and efficiency and meet strict hygiene standards.
In comparison, the heat exchangers in other major processing plants like petroleum, petrochemical etc need to be cleaned only once or twice a year.
In the dairy industry the cost due to the interruption in production can be dominant compared with the cost due to reduction in performance efficiency. Along with the cost, quality issues are equally important and in fact many times a shut down is required due to the concerns of product quality/contamination instead of performance of the heat exchanger.

The cleaning involves flushing high levels of caustic cleaning agents through the machines in order to remove residues build up and contamination. Once the cleaning is finished the machine must then be rinsed very thoroughly to remove all traces of these cleaning elements.

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