Cooling Water Systems
Cooling water systems are designed to remove heat from water used within an industrial process. Cooling via water is still seen as the most effective and low cost way to remove heat from a process, making cooling water systems a common aspect of industrial premises. Cooling water systems are also often found in the majority of modern offices due to the requirement for air conditioning systems. As cooling water systems are becoming more commonplace within industry, it is vital that the risk management and maintenance needs of these systems are monitored. At B & V Water Treatment we have over 35 years’ experience in dealing with various cooling water systems and all aspects of the required water treatment and maintenance needs.
Cooling water systems work by transferring heat from the water used within a process to the water within the cooling system via a heat exchange surface. This is usually achieved through cooling water passing around the outside of the pipework that holds the heated process water. Cooling water systems have many variations in design but the most common systems are recirculating systems that use either evaporative condensers or a cooling tower to dissipate the heat that it receives from the process.
Cooling towers use contact with air to cool the water that returns from a heat exchanger with process water. The air passed across or through the cooling tower pack then cools the water through evaporation. The cooled water then returns to the pond at the bottom of the cooling tower to be sent back into the system for further cooling. Passing the heated water through the pack allows for more contact time with the air that is being passed through the tower before the water re-joins the cooling tower pond.
This ensures that heat can be transferred from the returning water to the air. Drift eliminators are also used as a barrier between the returning hot water and the point at which hot air is released from the system. This is to ensure that the minimum amount of water is lost from the system. Make up water is needed within cooling towers as a proportion of the cooling water will be lost through the evaporation process.
Evaporative condensers are cooling water systems which are commonly used to cool closed systems. A proportion of the pipework from a closed system runs through an evaporative condenser, where water is sprayed over the pipework to remove heat from the system.
The build-up of scale within heat exchange equipment can cause a multitude of problems. It is estimated that even 1mm of scale on the surface of your heat transfer system could increase energy bills by up to 25%. This extra energy and the extra strain it adds means that the equipment ages at a much faster rate, requiring more repairs and replacement much sooner than expected. To effectively avoid the problems caused by scale in a cooling water system you need to know what scale is, the problems caused by scale and ways in which it can be treated.
Corrosion within cooling water systems causes two major system problems, the first of which is damage to the metals within the system which leads to expensive repairs and ultimately system failure. The other problem caused by corrosion in cooling water systems is the reduction of the system’s ability to transfer heat, which leads to an increase in the energy and water required for the system to complete the heat transfer needed. In order to effectively control corrosion within your cooling water system you need to first understand what causes corrosion within your system, the problems it will cause you and why, and methods of combatting it.
Cooling water systems are generally open evaporative systems which have the added disadvantage of microbes and dust from the air resulting in enhanced microbial growth within the system. These systems also release water vapour as part of their operation which means that they can potentially cause an outbreak of Legionnaire’s disease. Cooling water systems are a particularly high concern as the vapour released can spread across large distances and the number of people potentially affected would be much larger than in other systems. Consequently, understanding this risk and how it can be reduced is vital in managing the risk caused by microbiological fouling in cooling water systems.