Sea water – evaporator on a ship

User: THENAMARIS INC, Shipping company in Greece

We are proud on our first application back in 2001 in the marine industry. Right away we were pretty successful in solving problems around the desalination of seawater. Since then we could install Merus Rings on many other evaporators, getting the same results.

seawater evaporatorIn In the majority of the ships, there is one or more evaporator. This machine is used to make drinking water from ocean water. In order to achieve this, the solved salt and other inpurities has to be removed. Engineers found an economic way to run this process, the water evaporate using the excess energy of the engines.
The desalination works under lower pressure. This underpressure reduce the boiling point of the water and the temperature has not to be so high. The resulting steam is condensed and the water is later used as drinking water or for technical issues which requires water free of salt. The left over water, called brine is returned to the sea. One can see now RO systems as water treatment on certain vessels. At a reverse osmosis electrical power is needed to operate instead of excess heat of the motors.

Togehter with the sea or brakish water, salt and other substances from the sea enter the system. Therefore, the inner surface of the heat exchangers in the evaporator are coated with a crust of deposits. If the water isnt treated. This builds up over time and hinders heat transfer. As a result, the output decreases from day to day, until the required amount of fresh water can no longer be produced.

A traditional solution to this problem is chemical and / or manual cleaning of the system. Manual means disassembly, cleaning plate by plate and reassembling with new gaskets. Both methods are very expensive and time-consuming. No water is produced during cleaning.

Improving the performance of the evaporator with a Merus Ring

We installed two Merus Rings at each sea water inlet. Furthermore there were two Merus Rings at a chemically cleaned boiler (A) and two more at a second boiler (B) which hadn’t been cleaned for a long time. In both cases one Merus Ring would probably have been sufficient, to ensure the results we decided to play safe with two Merus Rings.

The result

In the first boiler (A) no cleaning was needed since the installation of the Merus Rings. Astonishingly the performance in the first month of the installation did not only remain stable but even increased from 28 to 31 t of fresh water in one day. The explanation for this is that chemical cleaning is not able to reach all areas of a piping system. Whereas the Merus technology can act wherever water is.

The second boiler (B) similar to (A) didn’t need further cleaning. The production volume increased very fast and reached its maximum performance soon. This means that the boiler is now fully clean and no further cleaning is necessary anymore.

Abandoning chemical cleaning is also a great benefit for the life time of the system as this can lead to heavy corrosion.


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