A cooling tower is an open system allowing to transfer energy by the evaporation of water. In the industry there are different types of cooling towers, each of those have their own water treatment characteristics. Evaporation and exposure to the outdoor elements render this environment prone to scaling, fouling and microbiological growth.
An appropriate water treatment program will ensure the proper operation of your cooling tower and will provide the following advantages:
- Optimization of energy efficiency
- Corrosion, scaling and fouling prevention
- Microbiological control and Legionella prevention
- Optimization of water consumption
Here are a number of our related equipment applications :
Monitour TM - Automatic feed and monitoring system
The performance of a water treatment program for cooling tower depends heavily on the stability of its application. This can only be achieved by using appropriate injection and monitoring systems.
Because of the massive evaporation resulting from the cooling process, the change of water within the circulation network is quick, typically at a rate of several times per day. Manual control of blowdown and chemicals injection result in large fluctuations of the water quality, which reduce or totally eliminate the effectiveness of a preventive treatment program against corrosion, scaling and microbiological growth.
To maintain satisfactory conditions, it is important to use appropriate equipment to monitor blowdown and chemical feed system.
At all times the equipment must allow the following functions :
Control blowdown by the continuous analysis of water conductivity;
Measurement of blowdown and/or make up water volumes;
Injection of inhibitors in proportion to water consumption;
Scheduled addition of non-oxidizing biocides and bio-dispersant;
In line analysis and continuous monitoring of the oxidizing biocide.
Cooling tower filtration
Filtration of water for evaporative cooling towers is a simple and non-expensive method to improve the overall system efficiency. Typically, cooling towers accumulate a lot of airborne particles, slime and scale that can get stuck on wet surfaces and eventually migrate into water.
A typical 200 ton cooling tower, running 1000 hours per year, can accumulate over 600 pounds of airborne and make up particles (ASHRAE Handbook, 2008 Ch 39.13). The cold water sump of a tower offers a perfect environment for the accumulation of mud, which obviously favors the growth of bacteria. The use of a filtration system does not replace chemical treatment but significantly reduces the accumulation of deposits that can provide a favorable habitat to the growth of microorganisms.
Note : Nominal tons of cooling represents the capability to cool 3 USGPM of water from a 95°F entering water temperature to an 85°F leaving water temperature at a 78°F entering wet-bulb temperature.
Design and selection
To properly select a filtration system, it is first necessary to assess the nature of the contaminants to be removed. The particle size and count analysis in water should be part of the design process and equipment selection. Also the capacity and the volume of the system need to be determined.
The filtration system can be installed through two methods : either on derivation of the cooling tower pump or directly on the basin.
Filtration technologies for conventional cooling towers include: