Increasing Water System Sustainability - Part 4:

Automating Chemical Feed and Control

  • 14 February 2023
  • Author: Allan Browning
  • Number of views: 1353
  • 0 Comments

Return on investment for a sustainable operation is linked to energy and water savings and ultimately the water treatment program. With increasing energy costs and water scarcity concerns, more than ever, pressure is being placed on facility managers to find ways to reduce usage.

An effective water treatment program is a critical part of the preventative maintenance of boiler and cooling systems. In many cases, the water treatment program can be engineered to improve energy and water efficiency, reduce chemical usage, and optimize results. Automating blowdown, chemical feed and control, and other treatment processes can effectively help make a water treatment program more sustainable.

Blowdown Control
Evaporative cooling water systems are widely used because they are much more energy efficient than air cooled units. In terms of raw efficiency, it takes 50 percent more electricity to operate an air cooled chiller than it does a water cooled chiller. However, effective water treatment is required to manage water usage and keep heat transfer surfaces clean so this efficiency can be maintained.

As the cooling water evaporates, dissolved solids are left behind and concentrate in the cooling tower water. To prevent the dissolved solids in the water from concentrating to the point where energy-robbing deposits and other problems occur, a portion of the tower water must be discharged from the system by a function called blowdown. A key water treatment objective is to maintain the minimum blowdown rate consistent with good deposit control. This is accomplished by adding chemicals to increase the solubility of scale-forming impurities and controlling the blowdown rate so the target cycles of concentration level is maintained in the tower water. Too much blowdown wastes water and increases chemical usage. Since energy is required to heat boiler water, water savings strategies in boiler systems also reduce energy usage.

The table below shows that in a cooling tower system, maintaining five cycles versus three cycles reduces water consumption by almost 17 percent and inhibitor requirements by 50 percent. However, insufficient blowdown can result in waterside deposits that reduce efficiency and increase energy costs. Because the blowdown rate required to maintain the target cycles varies as the tower evaporation rate changes throughout the day and from season to season, an automatic system is necessary for good blowdown control.

The Importance of Chemical Feed and Control
An effective chemical treatment program greatly impacts energy and water efficiency, as well as the overall cost of operation. The addition of chemical inhibitors allows high cycles to be maintained without efficiency losses and other problems. However, even the best water treatment chemicals will not provide good protection if they are not applied properly or in the wrong amount. Overfeeding water treatment chemicals is wasteful while underfeeding can result in corrosion, deposits, and microbiological growth problems.

Facilities serious about running sustainable operations closely monitor energy and water usage. Often, metrics such as the energy/water use per square foot of building space or refrigeration ton are used to track progress. Advanced online controllers are available to continuously monitor and adjust the water treatment program based on changing system demands. They can warn personnel when upset conditions occur, so minor concerns don’t turn into major waterside problems. They also allow data management and analysis to help optimize results and reduce costs. This automation enables high-performance water treatment programs that increase sustainability.

Automating the Water Treatment Program
Automated water treatment feed and control systems can support several key sustainable objectives by providing:

  • Good cycles control and precise chemical additions to maximize results
  • Reduced energy usage and greenhouse emissions
  • Lower water and chemical usage
  • Extended equipment life
  • Data to track sustainability improvement goals

Conclusion
The water treatment program for boiler and cooling water systems is integral to the operation of energy, water, and resource-efficient facilities. Obtaining optimal results from the water treatment program can have a significant impact and help meet sustainability and safety objectives on many levels. Contact Chem-Aqua to learn more and to schedule a consultation to automate your water treatment program.

Written by: Allan Browning

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