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checkMaximize cooling tower efficiency by improving water quality.

All PIM content was independently developed and reviewed to be vendor-, product-, and service provider-neutral.

Description

Managing the concentration of dissolved solids in the water recirculating through a cooling tower can lead to significant water savings.

  • Project Talking Points

    • Depending on the climate, cooling towers can account for up to 25 percent of a facility’s total water consumption.
    • Water is lost through cooling towers in four possible ways: (1) evaporation, (2) drift, (3) blowdown (i.e., water discharged from the system, typically to a drain), and (4) basin leaks or overflows. Makeup water must be added to replace lost water and maintain an appropriate concentration of dissolved solids.
    • Dissolved solids must be kept at an appropriate level of concentration to avoid scaling, biological growth, and corrosion.
    • In many cases, the amount of blowdown for a cooling tower is greater than necessary, resulting in wasted water. This performance improvement measure (PIM) focuses on reducing the blowdown rate by decreasing the amount of makeup water needed to keep solids dissolved. The key is to optimize cooling tower efficiency by finding the right balance between water consumption and concentrations of chemicals and solids in the water.

     

  • Triple Bottom Line Benefits

    • Cost benefits:  Reducing water consumption reduces  water and sewer costs.  As well, less water used means less water treated, so chemical treatment cost is also reduced.
    • Environmental benefits: Reducing the amount of water consumed also reduces the amount of treatment chemicals required, which in turn results in a lower volume of chemicals discharged to the waste stream and the environment.
    • Health and safety benefits: Saving money on wasteful and unnecessary tasks saves resources that can be used to accomplish the real mission of the hospital. Supporting water quality and conservation contributes to environmental stewardship and healthy communities.
    • Quality and outcomes - Metrics are in development. If you have suggestions, please  contact us or participate in the discussion below.

  • Purchasing Considerations

    If you have suggestions for purchasing considerations, or suggested sample contract language for any product or contracted service, please participate in the discussion below.

  • How-To

    1. Adjust the cooling tower blowdown rate to maintain total dissolved solids (TDS) at levels recommended by manufacturer specifications.  Or, as a rule of thumb, adjust the rate so the system maintains five concentration cycles (the ratio of TDS in the blowdown water compared to TDS in the makeup water). Consult a water treatment specialist to determine a regimen based on the quality of your makeup water and the maximum number of concentration cycles your system can sustain. A water treatment regimen depends on the quality and characteristics of the local water supply (e.g., hard water has more dissolved solids than soft water). Make sure the treatment specialist understands that saving water, without compromising system safety, is your priority.
    2. Consider installing a conductivity controller to automatically adjust blowdown. The controller will provide makeup water only when the conductivity of the discharge water exceeds a setpoint. Install with a data logger to track system performance.
    3. Consider installing flow meters on makeup and blowdown lines. Either install them with a data logger or be sure to include regular readings in your scheduled maintenance inspections. Use the data to calculate actual cycles of concentration and compare them with your target number. The data will also be useful for identifying and tracking system leaks and other maintenance issues. Check with your local water utility, as they may be able to source or provide ”deduct” meters which can factor, and then credit back, the amount of water that evaporates from tower operation.
    4. Identify additional opportunities offered by retrofit strategies to reduce cooling tower water consumption. Examples include:
      • Sidestream filtration, which uses external filters to remove sediment from the tower sump. This can be effective in areas subject to dusty atmospheric conditions.
      • Automated chemical feed systems, which monitor conductivity. These systems allow precise regulation of chemicals in the makeup water.
    5. Explore alternatives to chemical treatment, including ozonation, ionization, and UV systems. Contact a representative of your cooling tower manufacturer to review planned system upgrades and to confirm system performance parameters before you begin the work. Some components of the strategies listed can be obtained through the original equipment manufacturer.
  • Tools

    If you have an ROI tool, calculator, or similar resource to share, please contact us or participate in the discussion below. 

  • Case Studies

    • The Marshall Space Flight Center implemented innovative technologies to improve water efficiency and performance in one of its cooling systems. The program saved the facility more than 800,000 gallons of water in eight months.

    Do you have a case study to share? Please contact us

  • Regulations, Codes and Standards, Policies

  • Cross References: LEED

  • Cross References: GGHC

    • Operations: Facilities Management Credit FM 2.1-2.5: Potable Water Use Reduction: Total Building Reduction
    • Operations: Facilities Management Credit FM 2.8: Potable Water Use Reduction: Cooling Tower: Non-Potable Water Source
    • Operations: Facilities Management Credit FM 4.1: Building Operations & Maintenance: Staff Education
    • Operations: Facilities Management Credit FM 4.2: Building Operations & Maintenance: Building Systems Maintenance
  • Cross References: EEP

    If you have sample environmentally preferable purchasing language for products or contracted services to share, or other related resources, please contact us or participate in the discussion below. 

  • PIM Synergies

  • Education Resources

    If you have any information or resources to contribute, please contact us or participate in the discussion below.

  • More Resources

     

  • PIM Descriptors

    Water

    Level: Beginner

    Category List:

    • HVAC

    PIM Attributes:

    • Optimize Operations

    Improvement Type:

    • Operations

    Department:

    • Engineering/Facilities Management
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