The first cooling tower was designed during the Industrial Revolution and is used to extract heat from industrial, power and HVAC processes. If you asked the question “how to design a cooling tower” in the late 1800’s, the answer would be quite a bit different than the answer in 2012.
Today we have evolved substantially with improved knowledge around energy efficiency, water conservation, reduced emissions and overall environmental impact, worker safety, improved reliability, and aesthetics. Nevertheless, today’s conventional cooling tower basic design has many similarities to the design of a cooling tower over 100 years ago. This can easily be seen on the brochures of many leading manufacturers showcasing:
- Large top mounted fans operating in the hot, corrosive exhaust air stream exposed to the elements that can lead to devastating results to the process when they fail
- Ladders and handrails to routinely access mechanical equipment 15’-30‘ or higher above ground level
- Drift rates of .002% and greater with open air inlet louvers allowing significant chemically treated water to escape and land on adjacent ground, cars, equipment, buildings and humans
- Large unsightly stagnant water basins exposing basin water to the sun and natural elements allowing harmful breeding such as Legionnaires’ Disease
- Corrosive materials of construction such as galvanized metal that can leach harmful elements into the circulating water and deteriorate quickly
- Distribution systems with a single operating point that require entire cells to be turned off during off-peak operating conditions, which is the majority of the time, for optimal performance
- Distribution systems that can clog easily requiring maintenance personnel to routinely enter the tower box for maintenance
Many manufacturers have put an adhesive bandage on the conventional cooling tower design problem by offering an option to address the design flaw that most concerns each specific prospective customer. For example, a forced-draft design is offered when there are concerns of drift and top-mounted fans. A stainless steel or FRP design is offered when corrosion or long life expectancy is a concern. Basin sweepers are offered when concerns of stagnant basins arise.
Many of these options help reduce the concern. Unfortunately, they often do not always address the entire problem that is your primary concern (ex. SS basins when most of the structure is still galvanized) or create other unfavorable impacts (ex. having to maintain belts with many forced draft designs). Take care when designing your next cooling tower project to ensure your concerns are adequately addressed. If your only concern is initial cost, you will likely end up with a cooling tower that comes with many of the same design limitations of technology that was in play 100 years ago. If you seek out the latest technology available that addresses each of the design flaws listed above, you will likely find a relatively quick return on your additional investment and sleep much better if cooling tower operation is your concern. Think about “how to design a cooling tower” not only for 2012, but for the anticipated useful life of your next cooling tower. After all, you will live with the cooling tower and its corresponding energy efficiency, water consumption, environmental impact, safety, reliability and aesthetics for the life of the cooling tower.