KCF Technologies Blog

Maximize Cooling Tower Energy Efficiency Through Scrupulous Maintenance

A cooling tower fan at an university HVAC plant.
"Bringing Knowledge to People...Promoting Efficient Use of Energy" is the mantra of Energy Manager Training, a website mandated by India's Energy Conservation Act of 2002, which is financed jointly by the government of India and by the Federal Ministry of Economic Cooperation and Development of the government of Germany.  Among its pragmatic offerings is an unattributed three-page technical brief with some helpful "Cooling Tower Tips," presented in .pdf format.

"Reducing energy expenditures for your cooling tower may be as simple as regular maintenance.  This Technical Brief explains how proper maintenance will optimize heat transfer and help your equipment operate more efficiently.  It also identifies strategies for upgrading cooling tower performance."

Whether it's relatively small rooftop unit air conditioning a university, office building, or hotel, or one of the massive hyperboloid structures we associate with nuclear power plants, and large chemical complexes, cooling towers work by venting unwanted, or waste, heat that is carried by the cooling water into the atmosphere.

But maintenance matters, and costs of neglecting it can be steep:

"An improperly maintained cooling tower will produce warmer cooling water, resulting in a condenser temperature 5° to 10° F higher than a properly maintained cooling tower.  This reduces the efficiency of the chiller, wastes energy, and increases cost.  The chiller will consume 2.5 percent to 3.5 percent more energy for each degree increase in condenser temperature.  For example, if your chiller uses $20,000 of electricity each year, it will cost you an additional $500 to $700 per year for every degree increase increase in condenser temperature.  Thus, for a 5° to 10° F increase, you can expect to pay $2,500 to $7,000 a year in additional electricity costs.  In addition, a poorly maintained cooling tower will have a shorter operating life, is more likely to need costly repairs, and is less reliable."

Optimizing the performance of any cooling tower means keeping in check the process and problems that can plague them.  "The performance of a cooling tower degrades when the efficiency of the heat transfer process declines.  Some of the common causes of this degradation include:
  • Scale Deposites
  • Clogged Spray Nozzles
  • Poor Air Flow
  • Poor Pump Performance"
Poor air flow and poor pump performance often are readily detectable by excessive or uncharacteristic vibration.

All of these sources of degradation stem from unwanted elements in the water itself.  Thus the keys to maximizing energy efficiency in a cooling tower rely on:
  • Prevention of Corrosion (due to dissolved oxygen and/or acidic pH)
  • Prevention of Scale (due to dissolved minerals that precipitate out in evaporation)
  • Prevention of Fouling (due to dust, dirt, algae, fungi, and bacteria)
The brief recommends controlling and preventing all three through the use of Treatment Dosing Equipment: "In order for the treatment products to to work effectively, they must be properly fed into the cooling system.  Corrosion and scale inhibitors should be maintained at a constant level at all times, whereas biocides are most effective when applied in slug doses on a product alternated basis."

The good news is that even many neglected cooling towers can be returned to efficient operation with the right treatment: "It only takes three to six months to dissolve two tons of solid impurities from the coiler in a cooling tower after the installation of the chemical-free Aqua Correct physical water treatment.  The approximate two tons [of] deposits was the amount...removed from the cooling towers at the worldwide known dairy company MD Foods/ARLA as well as at the Danpo Chicken Slaughterhouse and in hundreds of other cooling tower plants."

Photo by Dr. Jeremy Frank/KCF Technologies.  All rights reserved.

Wireless Sensing + Vibration Energy Harvesting = "A Great Combination"

A SmartDiagnostics® vibration sensor and
harvester.  In his article "Wireless Condition
Monitoring Arrives (and Just in Time),"
ARC Senior Analyst, Harry Forbes says,
"...wireless sensing and vibration harvesting
make a great combination."
Established in 1896, Power Engineering magazine is "the comprehensive voice of the power generation industry that provides readers with the critical information needed to remain efficient and competitive in today's market."  That's why, for three years in a row, it has been named the most read and useful magazine in the power industry.  It is ably supplemented by Power Engineering Online, which provides up-to-the-minute energy news, stock quotes, five years of searchable editorial archives, power generation conference schedules and details, and an industry product and services guide.

Among the worthwhile articles in the online archive is "Wireless Condition Monitoring Arrives (and Just in Time)" by Harry Forbes, a specialist in power generation, transmission, and distribution and a Senior Analyst with the ARC Advisory Group.  His overview begins with a survey of then-new wireless predictive maintenance technology, followed by a short but insightful perspective on what it all means, and the future of equipment condition monitoring (ECM) and prognostic aqpproaches in the power gen industry.

So what does Forbes foresee?  To begin with, still greater challenges ahead:

"Today's utility engineer may be responsible for performance of a 500MW or 750 MW unit, where problems with any of roughly 50 rotating shafts located somewhere on the unit can affect unit availability.  Tomorrow's utility engineer is going to confront an even greater challenge.  For one thing, the low cost baseload generation of future power markets will include far greater amounts of wind power.  In the future, engineers will have to monitor the condition of a far larger number of machines, and the machines will not all be located within a few minutes walking distance from their desk."

Forbes believes "that the cost, flexibility, and other advantages of new wireless sensing technologies will expand the coverage of equipment condition monitoring to a far higher fraction of critical equipment in the power generation industry....This will make condition monitoring a greater challenge for utilities, who will rely on a much larger number of machines to deliver power (and profits) during peak hours."

The crucial question ahead: "What recommendations should a utility follow?"

"First, utilities include automated analytics and diagnosis (not just automated data capture) as factors in their evaluation of new EMC offerings."

"Second, they should use wireless sensing systems to expand both internal and external collaboration in the ECM area."

"Third, greater levels of collaboration also will be essential for condition monitoring in the future, so start building this capability now."

"And, finally, wireless sensing and vibration harvesting make a great combination.  Utilities should expect their suppliers to deliver products that leverage this match."

Photo by Christopher Shannon/KCF Technologies.  All rights reserved. 

SmartDiagnostics® Feature Highlight: New Cloud Capabilities

With the release of version 1.2 in November 2012, KCF Technologies has added capabilities to the SmartDiagnostics® suite.

The objective of SmartDiagnostics® in the Cloud is to make this inexpensive yet powerful monitoring system even easier to install and operate.  To do so, SmartDiagnostics in the Cloud uses a pre-configured collection server to deliver data to the customer from a a centrally located system in the Cloud, thus allowing the customer to implement the system with minimal training and expertise.

SmartDiagnostics® in the Cloud is a customizable platform for monitoring the health and usage of a variety of assets.  The system collects, processes, displays, and reports dynamic sensor information from a variety of wireless sensors to provide near real-time diagnostics.  The system enables management by exception through the use of configurable monitoring bands that interpret sensor readings to determine whether there is an alarm condition that needs to be acted upon.

"Predictive maintenance offers huge cost savings and productivity improvements by enabling actionable data from rotating machinery," according to KCF President Dr. Jeremy Frank.  "However, the sensors must be low-cost and easy to deploy to deliver on the value proposition.  Eliminating the wire cuts out a major deployment cost, and the next step is to make the flow of data automatic and simple."

"The Cloud offers this capability, because data can now flow from the sensor to the collection server, to the Cloud, and down to the user software with minimal local setup of data infrastructure.  The benefit to the user is the easiest possible installation to achieve low-cost predictive maintenance."

Also new to SmartDiagnostics® in version 1.2 is the ability for users to setup e-mail or text alerts to warn them of potential failures when they are away from the computer.

Of the new e-mail alert feature in SmartDiagnostics®, Dr. Frank added, "Modern day plant managers are responsible for successful operations of the plant, and the reality is that predictive maintenance practices are rarely the primary focus.  Often, that means it is difficult to pay attention to the health of rotating machinery, which creates a challenge for taking full advantage of predictive maintenance."

"E-mail alerts help address this challenge by automatically bringing warning or alarm condition to the attention of the right person, increasing the likelihood of catching a developing problem proactively."

You can learn much more about KCF Technologies' SmartDiagnostics® technology here.

All Vibration Monitors Are Not Alike: Troubleshooting vs. Predictive Maintenance

Ken Piety is the Vice President of Technology at Massachusetts-based Azima DLI, which "delivers machine health reliability solutions with global reach that reduce risk, improve safety, increase production, and optimize efficiency" at pulp and paper plants and other facilities that use rotating machinery.  Piety also narrates a brief but brilliant little video titled "Why Vibration Troubleshooting Instruments are Inadequate for Predictive Maintenance" (PdM) on the Reliable Plant website and on YouTube.

"Sometimes the distinctions can be confusing," Piety says, noting that tools involved in both troubleshooting and PdM, "often do the same tasks.  Both instruments often measure vibration, frequently [taking] detailed measurements like vibration frequency spectra...and both instruments have software associated with them, and may do detailed fault analysis.  However, the fact that there are many similarities does not mean the instruments are capable of accomplishing the same purposes."

"With predictive maintenance...you are able to have a current and up-to-date indication of the health of your machines, and to do that it's important that those machines be screened or scanned on a periodic basis, that their state of health be evaluated....It's extremely important in a predictive maintenance program to capture machines that are beginning to fail at a very early stage.  Often we talk about this as incipient failure detection, and we may be able to capture the fact that the machine is going to fail weeks--perhaps even months--ahead of time."  Accurately anticipating such failures before they happen means parts can be ordered and needed maintenance scheduled when it is most convenient, thus maximizing uptime.

"For a predictive maintenance program, it's common that, perhaps on a monthly basis, a technician will go out and screen these machines with a vibration analyzer, collecting large quantities of data, bring those back, scanning the information, and determining out of the hundreds of machines that you collected data on, which of the few machines may have developed a problem.  [The technician's] task then is to analyze that information, and determine what are the specific faults , and recommend the actions...that need to be taken to correct those faults, and what are the priorities of those actions."

"This is where the overlap begins with a troubleshooting instrument," which is, Piety notes, "capable of collecting and analyzing vibration data, and trying to make a determination of what's wrong with the machine.  However...if you haven't been screening on a periodic basis, how do you know when to do that?"

"Typically, the fault [that the troubleshooting instrument detects] is going to have to be in an advanced enough state that it's been detected by people just from their ears, or their eyes, or the smell of something burning, so it's in a very advanced state.  Even though you may be able to analyze what is wrong with the machine, there's less time to be able to take action and correct that in a way that will not cause the plant to be shut down or to have to reduce production."

"Summarizing," he concludes, "I would say that...vibration analyzers that are used for predictive maintenance programs and those that are used for troubleshooting have many similarities, but the goals and what they can accomplish for you are vastly different.  A troubleshooting instrument is used in an isolated situation to solve a single problem, versus monitoring large numbers of machines in order to optimize the maintenance that is performed in your plant."

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