Cooling water treatment is necessary to protect your system against four of the main problems that exist for cooling systems; fouling, corrosion, microbial contamination and scale deposits.
Why are cooling systems needed?
Many industrial sites have processes that are temperature dependent and require a controlled temperature to enable the process to work effectively and efficiently so that the correct product or quality can be produced. Cooling water systems are also used for air-conditioning in many areas that comfort cooling is required such as for offices, hotels, homes, hospitals, and factories.
Why is water used for cooling?
Water is readily available, relatively inexpensive, and easily handled. Water also has a large heat absorption capacity. Water also has the capacity to absorb heat from a process via a heat exchanger surface.
Why is scaling and fouling of heat exchangers such a problem?
Scaling can be caused by the precipitation of compounds that become insoluble at higher temperature such as calcium carbonate. (hardness scale) Scale is an insulator and reduces the efficiency of the system by reducing heat transfer; it also reduces the flow rate through the system. The reduced flow rate can contribute to fouling where silt and corrosion products deposit in low flow areas of the heat exchanger. This can cause blockages and under deposit corrosion can occur. This reduction means that the cooling water may not remove sufficient heat from the process. This can lead to productivity of the plant being reduced.
Why is microbial growth a problem in a cooling system?
Microbial growth can cause fouling in a cooling water system as well as pose health risk. Algae and bacteria that form sessile deposits can cause under deposit corrosion leading to tube failure. The deposits are also capable of blocking off water flow reducing the efficiency of the cooling system. Bacteria can be health hazard in cooling towers as these operate at human body temperature making them an ideal incubator for water borne human pathogens eg. Legionella. A properly administrated biocide programme is used to keep these potential problems under control.
What are some of the more common cooling systems encountered in Australia?
There are three main types of cooling water systems used in Australia, open recirculating, once through systems, and closed recirculating systems.