Our Cooling Tower Cleaning and Disinfection Programs contribute directly to key intangible value drivers that do not appear on financial statements, by improving the customer experience, increasing worker productivity and enhancing brand equity. The Cleaning and Disinfection Programs also contribute indirectly by creating value for external stakeholders including communities, public interest groups, and regulatory agencies.
Cooling Tower Cleaning maintains water efficiency in operations and maintenance, federal agencies should:
Calculate and understand "cycles of concentration." Check the ratio of conductivity of blowdown and make-up water. Work with your cooling tower water treatment specialist to maximize the cycles of concentration. Many systems operate at two to four cycles of concentration, while six cycles or more may be possible. Increasing cycles from three to six reduce cooling tower make-up water by 20% and cooling tower blowdown by 50%.
The actual number of cycles of concentration the cooling tower system can handle depends on the make-up water quality and cooling tower water treatment regimen. Typical treatment programs include corrosion and scaling inhibitors along with biological fouling inhibitors.
Install a conductivity controller to automatically control blowdown. Work with a water treatment specialist to determine the maximum cycles of concentration the cooling tower system can safely achieve and the resulting conductivity (typically measured as micro Siemens per centimeter, µS/cm). A conductivity controller can continuously measure the conductivity of the cooling tower water and discharge water only when the conductivity setpoint is exceeded.
Install flow meters on make-up and blowdown lines.
Check the ratio of make-up flow to blowdown flow. Then check the ratio of conductivity of blowdown water and the make-up water (handheld conductivity meters can be used to determine the relative mineral concentration of the recirculating and make-up water). These ratios should match the target cycles of concentration. If both ratios are not about the same, check the tower for leaks or other unauthorized draw-off. If the system is not operating at, or near, the target cycles of concentration, check system components including a conductivity controller, make-up water fill valve, and blowdown valve.
Read conductivity and flow meters regularly to quickly identify problems. Keep a log of make-up and blowdown quantities, conductivity, and cycles of concentration. Monitor trends to spot deterioration in performance.
Consider using an acid treatment such as sulfuric, hydrochloric, or ascorbic acid where appropriate. When added to recirculating water, acid can reduce the scale buildup potential from mineral deposits and allow the system to run at higher cycles of concentration. Acid treatment lowers the pH of the water and is effective in converting a portion of the alkalinity (bicarbonate and carbonate), a primary constituent of scale formation, into more readily soluble forms. Make sure workers are fully trained in the proper handling of acids. Also, note that acid overdoses can severely damage a cooling system. The use of a timer or continuous pH monitoring via instrumentation should be employed. It is important to add acid to a point where the flow of water promotes rapid mixing and distribution.
Select a water treatment vendor with care.
Tell vendors that water efficiency is a high priority and ask them to estimate the quantities and costs of treatment chemicals, volumes of blowdown water, and the expected cycles of concentration ratio. Keep in mind that some vendors may be reluctant to improve water efficiency because it means the facility will purchase fewer chemicals. In some cases, saving on chemicals can outweigh the savings on water costs. Vendors should be selected based on "cost to treat 1,000 gallons of make-up water" and “highest recommended system water cycle of concentration." Treatment programs should include routine checks of cooling system chemistry accompanied by regular service reports that provide insight into the system’s performance.
Ask the water utility if it provides sewer credits for evaporative losses, which can be calculated as the difference between metered make-up water minus metered blowdown water.
Implement a comprehensive air handler coil maintenance program. As coils become dirty or fouled, there is an increased load on the chilled water system to maintain conditioned air set point temperatures. Increased load on the chilled water system not only has an associated increase in electrical consumption, but it also increases the load on the evaporative cooling process, which uses more water.
The following retrofit options help federal agencies maintain water efficiency across facilities:
Consider installing a side-stream filtration system. These systems filter silt and suspended solids and return the filtered water to the recirculating water. This limits the fouling potential for the tower system, which is particularly helpful if the cooling tower is located in a dusty environment.
Install a make-up water or side-stream softening system when hardness (calcium and magnesium) is the limiting factor on cycles of concentration. Water softening removes hardness using an ion exchange resin and can allow you to operate at higher cycles of concentration.
Install covers on open distribution decks on top of the tower. Reducing the amount of sunlight on tower surfaces can significantly reduce biological growth such as algae.
Consider alternative water treatment options, such as ozonation or ionization and chemical use. Be careful to consider the life-cycle cost impact of such systems.
Install automated chemical feed systems on large cooling tower systems (more than 100 tons). The automated feed system should control chemical feed based on make-up water flow or real-time chemical monitoring. These systems minimize chemical use while optimizing control against scale, corrosion, and biological growth.
The following replacement options help federal agencies maintain water efficiency across facilities.
Get expert advice to help determine if a cooling tower replacement is appropriate. New cooling tower designs and improved materials can significantly reduce water and energy requirements for cooling. Replacing a cooling tower involves significant capital costs, so be sure to investigate every retrofit and operations and maintenance option available, and compare the costs and benefits to a new tower.