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Scale and corrosion in 3 independent cooling systems stopped


Company:Nuplas Industries, Jebel Ali Freezone Dubai, UAE
About the customer:
Nuplas Industries is a well known company producing packaging material based on polymer, typically used in the food or pharmaceutical industry. Also there is a line of extruder producing drinking cups. The production was started in 1997 in the Jebel Ali Free zone in Dubai, UAE, and has been constant extended , both in size and quality of production. Today Nuplas Industries is supplying more then 25 countries, with their different lines of products.

 
The Problem:
The processing of polymer and similar products requires cooling in certain production steps. The customer plant is located in the middle east, where during the summer temperature might reach 40°C and more, so cooling is required for the labor and for some of the machinery. For the cooling in the plant there are 3 independent cooling systems, two chilled water systems and one open cooling system with a cooling tower. All these cooling systems shared one common problem, in all systems corrosion was a big issue and also scaling could be found. Additional in the cooling tower the problem of
algae could be very easy seen, as the color of the water in the cooling tower sump was bright green.Although the corrosion and fouling happened even with chemical treatment of all 3 cooling systems. These fouling problems required regular manual cleaning of the heat exchangers. So there has been regular cleaning every 2 to 3 month of the different machines.The corrosion in the system has been so bad, that the water in the chilled water tank or the cooling tower sump has been dark brown, in spite of regular replacing the entire cooling water. The customer already considered to replace all the pipe system, to avoid any shut down of the production, do to no supply of cooling water.

The Solution:
None of the different cooling loops is longer then 200 meter, so only two Pursanova DiskTM have been installed in each cooling loop. In addition, at the feed line of the city water one more Pursanova DiskTM was installed. The cleaning of the system took place in two steps. After the installation, the former setup of the water treatment hasn't been changed. After 30 days the half of the water was replaced. It could be found a lot of thicker scale and rust particles in the sump or in the chilled water tank. Seeing this, the chemical additives has been stopped, after another 30 days again half of the water has been replaced.

  The Monitoring:
cleaned pipe of chilled water systemIn the first step of the cleaning process it already could be recognized a lot of material coming out of the system. Also in the cooling tower, the algae turned brown and fall down to the bottom of the cooling tower. As there is no high sophisticated machinery installed to monitor the water quality, pipes and heat exchangers have to be opened to be inspected and checked visually. The most obvious sign about the cleaning of the system and that the corrosion has come to a stop, was the color of the cooling water itself. It became cleaner and cleaner. After the second replacement of the water, the cooling water has the same color as the city water has. So no more corrosion takes place in the pipes and
machinery. There is no requirement of shutting down and cleaning the various heat exchangers. The performance of the cooling in the plant is now constant at the design level of the system.

The Commercials
First, the manager of the plant didn't see too many commercial benefits, as the cost of the Pursanova DiskTM has been almost as much as the cost of the chemicals used before. This opinion changed after seeing how well Pursanova TM performed. Not only all the chemical treatment is stopped, but also the results are far better than they have ever been before. Looking on the fact there is no need of cleaning the equipment anymore, this is nowadays done only during the regular shutdown period, the calculation looks totally different. There is no emergency shutdown anymore, so the production time of the plant has increased. Also, the energy balance is positive. As there is no fouling in the heat exchangers anymore the produced cold can be transferred at design level into the cooling water. Considering all the improvements done by Pursanova TM, the ROI is less than 6 months.