Cooling Water Treatment
Cooling water is needed, as the name tells, to cool down something or to get rid of unwanted heat. Air has to be cooled mainly for air conditioning, product has to be cooled after certain heat processes and machines or processes has to be cooled down, because most machines produce unwanted heat as a side effect, which has to be brought down in order to run the machine properly.
There are either open cooling water systems, where a cooling tower is involved and therefore the water is open to the surroundings, or so called closed cooling system, where the water is cooled by other meaning and all time circulated and reused. We will concentrate here on open cooling loops only. Here you get an overview about cooling water systems.
The principal how this cooling water is distributed is more or less the same in all installations. There is a cooling tower or a row of them, from there a pipe network is supplying the cooling water to all the consumers connected to the system. Such consumers are heat exchangers of some sort, either direct build in a machine, or a heat exchanger, where on the one side cooling water is applied, and on the other side the liquid or gas, which has to be cooled down.
In a cooling tower some of the cooling water is evaporated, this evaporation is cooling down the remaining cooling water, using the effect of the evaporation heat. Very simple explained, the water needs a certain amount of energy to change from the liquid phase (water) to the gas phase (vapor), this energy is taken from the environment (as well the water) and so water is getting colder.
As only water is evaporated, the concentration of solids or solved parts such as salts or minerals in the remaining water is increasing all the time during this process. This leads over time as more and more water evaporates, to a higher concentration of solids (TDS) in the water. As higher the TDS in the cooling water, as more likely there will be technical problems in the system, such as fouling and scaling.
In order to avoid this technical problems, the common method to counter these problems is to replace some of the cooling water with fresh water. This is called blow down or bleeding. In most systems, this happens automatic. There is set a threshold for TDS or conductivity, once this limit is reached a blow down valve or a bleeding valve is open and drain a certain amount of water, which is then replaced by the feed water.
As an example, if the blow down happens at a concentration of 2.500 TDS and the feed water holds only 100 TDS, the overall concentration of the cooling water will be lowered.
What next to all users of a cooling water system are doing today, they are adding chemicals in the cooling water. There are chemicals against scaling or fouling, there are chemicals against corrosion and in most cooling systems also chemicals against bio activities in the water. In most cases we see in the field, there is a cocktail out of all three major used chemicals added to the cooling water, which gives significant cost and effort. There are the cost of the chemicals itself, the dosing equipment with its sensors and control units, as well there are the costs of logistic to get supplied with the chemicals, to store them and bring them to all the dosing points in the system.
MERUS is fighting all the arised technical problems in the cooling water with the MERUS Rings.
increased use of the water
Today MERUS has a row of certified cases, where entire cooling loops, including the cooling towers, all the heat exchangers and other consumers are taken care off. With the result, that there no need to use chemicals to treat the cooling water, and no problems arise in the cooling system. In addition MERUS is able to run a cooling system with a far higher COC (cycle of concentration) or far higher TDS, then ever possible when using chemicals. This higher TDS lead to significant savings of water. We are now working on projects, where the target will be to run the cooling loop with less then 50% of the water.
See as well case studies: algae cooling tower, biofouling refinery, cooling system refinery, scale in cooling loop. Also a calculator about saving of water.
To understand the used abreviations please see the glossary.