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Corrosion and scaling in mould forms PET bottle cooling system


Company: Coca Cola H.B.C. AG, Thessaloniki
Responsible: Mr Tsoutsas and Mr. Kouroglou

Description of the problem and its negative consequences
  The client is a license taker from Coca Cola and distributes the products, not only in Greece but as well to all European neighbors. A closed loop for cooling down hundreds of mold forms is used for his production of PET bottles. The water is cooled by plate heat exchangers.
Due to a small amount of leaking of the loop, they have constantly added some fresh water to this loop. Through this fresh water, all the time was added some new limescale as well as new oxygen in the loop.
This oxygen causes new corrosion, and the loop has to be cleaned on average all 14 days because of rust and a little scale which results in significant cost, not only from the cleaning and the chemicals, but even more from the shutdown of production for several hours. This cleaning was not always possible in time and has lead to serious quality problems at the bottles themselves. The vessel jacket has to be chemically cleaned at least every six months.

Our solution
We installed one Pursanova TM in the cooling loop. In between the heat exchanger and the molds at the machine. It was installed very near to the mold forms, in order to get the best possible results in the forms.

In which way our customer checked the results of the trial

1. Starting the day of installation of Pursanova TM, daily samples of the water were checked for iron content by the companies own labor. In a totally closed loop, it was to be expected, that the iron content in the water would increase, due to solving of the existing rust in the pipes and the mold forms. But due to the small leakage, the rust and the scale was drained from the system as well. So it could be seen, that the iron content in the water decreased steadily and stabilized on a very low and acceptable level.
2. After several inspections of the mold forms, it was noticed that there no corrosion or lime scale in the mold forms at all. As well, there was no need to do a chemical cleaning. The big advantage for the client is that the quality of the PET bottles is constantly high, and there is no need for a breakdown of the production which saves a lot of money.