Water Treatment for Cooling Towers

Water Treatment for Cooling Towers

Water cooling towers are used in various industrial processes to cool process equipment such as machinery and presses, chillers, and air-conditioners to prevent overheating and maintain an ambient air temperature. Water leaves the cooling tower in a few different ways, mostly through evaporation. A small amount of water may leave the cooling tower through drift, small droplets, or mist.

Water is also removed from the cooling tower through blowdown, which prevents scale from forming within the system and causing damage to piping and equipment. Blowdown involves controlling the concentration of water that becomes contaminated with dissolved solids such as magnesium, silica, chloride, and calcium, left behind as water evaporates from the tower. Monitoring and controlling the amount of blowdown is required to maximize energy efficiency and water conservation and to know the correct amount of makeup water to be added to the system.

A cooling tower that is properly maintained and operated should not experience water loss due to leaks or overflows. If this occurs, check system valves and float control equipment, and call a process equipment specialist.

The Importance of Water Conditioning in Cooling Towers

Cooling towers are often located in a dark corner of a plant, where maintenance could be overlooked if not for following a preventive maintenance program combined with using quality pumps and process equipment. Precise water conditioning in cooling towers saves water, reduces chemical consumption, and optimizes overall plant operations. A preventive maintenance plan should include all stakeholders such as the building maintenance technician, outsourced maintenance and water treatment companies, the chemical supplier and process equipment supplier.

Water conditioning must include disinfection and control of bacteria to prevent microbiological fouling. While corrosion and scaling are important concerns in water treatment systems, microbiological fouling can cause significant and costly problems.



Preventing Bacteria is Critical in Cooling Systems

Cooling systems are by nature wet and warm, an ideal environment for microbes to flourish. Bacteria grows on condensers, algae can form on cooling tower components exposed to the sunlight and fungi can form on wooden structures, leading to structural failure. Biocide treatment is critical to maintain the integrity and performance of any cooling system.

Bacteria is broadly classified into three categories:

  • Aerobic – oxygen is utilized in the metabolic process
  • Anaerobic – survive in oxygen free environments by utilizing other sources of energy such as nitrates or sulfates
  • Facultative – survive in either aerobic or anaerobic environments

Bacteria thrives when settling on a surface by secreting a layer of protection, a film that collects silt from water and continues to grow thicker. This layer of bacteria reduces heat transfer, thus reducing operational efficiencies in cooling towers. The bacteria at the surface may be considered aerobic, while anaerobic bacteria underneath continues to flourish. These microbes, left untreated, will generate harmful compounds and acids that will directly attack metal equipment. This causes an anodic reaction, oxidation, and corrosion. Pitting is a common result, causing premature tube failure.

Microbial Treatment with Consistent Biocide Dosing

Microbial treatment consists of a controlled feed of a non-oxidizing biocide with a quality dosing metering pump to kill organisms before they can settle and multiply on cooling tower fill, condenser tube walls and other areas. Different treatment methods exist such as conventional chlorine, although chlorine chemistry germicidal effectiveness declines dramatically with an increased pH level over 7.5. Liquid bleach (NaOCl) feed has replaced gaseous chlorine for water treatment at many facilities.

When using any chemicals, safety is the number one concern and a critical consideration when handling non-oxidizers. Proper personal protective equipment (PPE) is mandatory as many of these chemicals that attack microbes also attack human cells. Reliable pump processing equipment from quality manufacturers helps to reduce risk in water treatment applications.

Grundfos Pump Solutions for Cooling Water Treatment

Grundfos is a top manufacturer in pump processing equipment offering intelligent solutions with quality equipment and data management. Grundfos iSOLUTIONS offers precise dosing and monitoring along with a cloud-based remote monitoring system and chemical management app. This precise pumping solution improves operator safety and ensures that the right chemicals are used at the right amount. All relevant data is measured online with automated compliance reporting available.

Grundfos SMART Digital dosing pumps employ stepper motor technology to prevent vapor lock caused by the accumulation of gas in the pump head. The AutoFlowAdapt feature adjusts the pump speed to maintain constant pump flow regardless of system changes.

Illinois Process Equipment, IPE, is a leading Midwest supplier of quality pumps and process equipment from the top manufacturers such as Grundfos. We offer complete process equipment solutions including system design, installation, testing and customized solutions to meet your specifications. Contact us to learn more about improving water treatment for cooling towers in your industrial process.