Marine Growth Box Cooler

On a seagoing vessel there is in general a lot of cooling required. This is done traditionally, by using seawater, bringing into the vessel through the sea chest, and then use this seawater for cooling and as well to produce drinking water in a so called Fresh Water Generator. Bringing in hugh amounts of seawater inside a vessel causes the well known problems inside the vessel. As seawater leads to corrosion in pipes and equipment, fouling in the heat exchangers, also more and more problems with maritime growth such as barnacles, mussels, etc. occur.
The maritime industry is constantly  looking for new solutions to reduce the problems inside the vessel. So the so called box coolers are one approach to solve these problems.
What is a box cooler. In principle this is a pipe bundle, as known from tubular heat exchangers, which is put direct in the seawater, whereas the seawater can be used direct for the cooling of the different processes on a vessel. Inside the tubes there is cooling water circulated, used for the cooling of the engine. Outside there is seawater. This pipe bundles are installed in special compartments, where the ship is open to the sea so all time seawater is around the tubes of the box cooler.  See as well picture above, where there is shown a fresh cleaned tube bundle  using hydro jetting. As can be seen when using hydro jetting, not all the scale could be removed.
As seawater is known causing problems, such as scaling, corrosion and fouling, there are taken precautions, to avoid the corrosion for instance  material is choosen which is inert against corrosion. Two problems remain, there is scaling and a very big problem is the marine growth.
Classical methods as using chemicals to avoid scale or even sea growth are not possible to use in this case, as the chemicals would be needed to put direct in the seawater, what will never work due to the amount of seawater and as well due to the regulations of IMO and other authorities. So what will happen over time the box cooler will be full of all kind of marine growth as can be seen on the picture. You can hardly see the pipes due to the massive growth happening there. The picture to the right was taken at a vessel, after one year of operation. It was found that especially inside the tube bundle all is full with this stuff. It is very obvious, having a bundle like this, where hardly any water or at least far less can pass through, the efficiency of the cooling will be very less. So the procedure today is as soon the cooling is not sufficient anymore, the box cooler has to be removed, cleaned and brought back in operation. Of course during the cleaning the vessel cant be in operation, so this cleaning is very expensive for the shipowners.
Our customers facing such problems have approached us if Merus might be able to solve or at least lessen this problem of the fouling. The difficulty in this case, a Merus Ring cant be installed in this compartment or the sea chest either. So what we are doing now is to install Merus Rings on the inside of the vessel on the line where water is circulating. The idea is, when inside the tube bundle all the water is treated by Merus, there should be also some effect on the outside of the pipes. This we already know from other cases. So we have established several long term trails on various vessels, to find out, how much Merus can improve the situation. Will the fouling be less, so the cleaning cycles of the box cooler can be extended, or will the Merus Rings even be able to keep the clean or nearly clean.
The development of the fouling in the box cooler will be regularly checked by divers from outside the vessel. Also the performance of the cooling will be closely monitored and compared to historical data.
To get an overview what else Merus is doing in the marine, please click here.