The fouling in heat exchangers and the resulting cleaning efforts, is a common task in many companies.
Every heat exchanger includes two sides. Usual on the one side there is the product, for example a liquid or gas with a specific temperature. This product is brought to an other temperature level by the liquid on the other side. So it is either cooled down or heated up.
The fouling factor
The fouling factor is an indication of how strongly a machine tends to foul. The fouling factor number one is the character of the liquid itself. This means that impurities dissolved or suspended in the fluid will form incrustations on the heat transfer surfaces.
Furthermore, the type of heat exchanger, if it is a plate or shell-and-tube heat exchanger. The resistance against the liquid flow, the velocity and temperature of the fluid are another factor.
Fouling and incrustations impede the heat transfer or in other words the fouling impede the heating or cooling performance of the heat exchanger. The thicker and harder the deposits are, the less heat is transferred.
The waterside of the heat exchanger
On this page we concentrate on the cooling water side in a heat exchanger. This is the main application for the Merus-Ring and comes up in almost every project. There are also cases where we deal with the product side. But these are very specific solutions for our customers, because no two products are alike.
In open cooling water systems, deposits – the result of fouling – form depending on the amount of total dissolved solids (TDS) in the water. A rather clean river water, causing less fouling, then a seawater with several thousands of TDS. As higher the TDS, as more calcium carbonate or other minerals are settling on tubes and surfaces.
Is the cooling system closed, rust and corrosion due to aggressive substances in the water is found.
As the waterside is exposed to various external influences biofilm can form easily and fast. Biofouling occurs where algae or bacteria enters the cycle with the water and settles at the rough pipe walls (due to deposits and corrosion).
Heat exchangers with these deposits need to be cleaned regularly. Therefore the heat exchanger is opened and its parts are cleaned manually, often with chemical cleaning agents. For a big tube bundle heat exchanger this means a production stop for several days.
What can Merus do to stop heat exchanger fouling?
We are able to reduce existing deposits and in many cases stop fouling completely. The Merus Ring is installed at the inlet to the heat exchanger. If there is fouling on both sides, two Merus Rings are needed at both inlets. If the cooling cycle includes several heat exchangers it is not necessary to install one Ring ahead of each heat exchanger. It is sufficient to install the Merus Rings in selected areas.
After the installation deposits which substance is soluble in the liquid are solved and don’t settle anymore. In case of water often minerals become deposits. The Merus technology has the effect of a higher solubility of these minerals in the water. This effect is not limited to watery liquids. On the product side also oily liquids, crude oil or chemicals can be treated. To which degree the solution is applicable to other liquids has to be decided or tested individually.
The astonishing result of the water treatment is that the heat exchanger is nearly self cleaning after the installation of a Merus Ring. Numerous cases and customers prove that after some weeks nearly blocked heat exchangers were clean again – without chemical or manual cleaning.
The Merus Ring does both – removing existing deposits and stopping new deposition. Therefore fouling is stopped.