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Controlling Boiler Operating Costs

Jan. 6, 2015
This article discusses several strategies for maximizing boiler efficiency and uptime.

Boilers represent a significant investment. Naturally, then, it is incumbent upon building owners and operators to ensure their boilers are running properly and efficiently. Insufficient inspection and care of a boiler system can lead to a variety of problems. Repairs can be extremely costly and lead to downtime, which most operations can ill afford.

This article discusses several strategies for maximizing boiler efficiency and uptime.

Descaling

The water going into a boiler contains minerals. As the boiler evaporates water and produces steam, the minerals bake out on boiler-tube surfaces. This scale buildup significantly impairs the ability of heat from burned fuel to raise the temperature of water in the boiler high enough to produce steam. As a result, more fuel is needed. Additionally, the scale buildup increases the likelihood of tube leaks, as corrosion processes occur underneath. This leads to increased maintenance costs.

Boiler inspectors typically will say a boiler with light to moderate scaling on tube surfaces is fine to operate. Although such a boiler is safe to operate, its efficiency will be reduced. In such cases, studies by the U.S. Department of Energy (DOE) show, fuel bills can be as much as 5 percent higher than they would be if the boiler tubes were clean.

To clean a boiler’s waterside, use a chemical descaler containing corrosion inhibitors. After descaling, a boiler’s fuel efficiency and heat transfer will increase and fuel costs will go down.

A boiler tube before (top) and after chemical descaling.

What other steps can you take to ensure an efficient boiler?

Testing/Monitoring

Like anything, boilers sustain wear and tear over time. Boiler logs are an effective way to track performance and detect problems. Regular monitoring of boiler-system performance highlights issues such as exchanger fouling, dirty burners, improper firing ratios, and flame impingements.

A boiler-maintenance program should include regular efficiency testing, which will reveal trends that indicate when the boiler needs to be cleaned. For example, an increase in stack temperature frequently signals soot or scale buildup. An electronic combustion-efficiency tester should be considered standard for a maintenance program. These testers are essential for tuning a burner properly. Many models of testers with the ability to measure and/or calculate net stack temperature, oxygen, carbon monoxide, carbon dioxide, nitrous oxide, excess air, combustion efficiency, and more are available. There are models to fit every need and budget. Comparing data from test to test helps to pinpoint maintenance requirements.

Boiler operating logs not only aid efforts to achieve efficiency goals, they identify potential safety and operating issues. They are a great tool for facility managers and boiler operators. Every person involved with a boiler should have a solid understanding of the operating log, as well as what to monitor and review.

The National Board of Boiler and Pressure Vessel Inspectors outlines the responsibilities of those involved in developing a boiler operating log:

  • Operator: takes boiler readings and ensures accuracy and initial analysis.
  • Management: implements the log program and supervises its ongoing maintenance.
  • All persons involved ensure the log is retained in accordance with facility policy.
  • All persons involved examine the log to identify trends and then act upon or recommend action in response to those trends.

The National Board suggests reaching out to boiler insurance companies for sample log sheets.

Visual Inspection

The DOE recommends a visual inspection whenever a boiler is shut down. There are video scopes that help to determine whether all scale and debris were removed during cleaning. Boiler operators and facility managers should examine boilers for signs of damage, corrosion, overheating, and leaks, in addition to checking valve, control, and safety-device function. All interior openings should be checked for debris and corrosion, while controls should be reviewed and tested to make sure gauges are working correctly. Repairs and replacements should be initiated as soon as possible.

Boiler inspections should be conducted regularly—at least once a year—depending primarily on the environmental conditions affecting the system. Proper testing, cleaning, and inspection of a boiler system can reduce fuel consumption and allow systems to operate more efficiently. Higher efficiency and cleanliness reduce repair costs and lengthen service life.

Conclusion

Cleaning and regular maintenance are critical to preventing issues and ensuring HVAC equipment is functioning reliably. Thanks to the variety of HVAC maintenance products on the market today, boiler cleaning is simpler and can be performed faster than ever before. An investment in proper maintenance pays for itself in short order by creating a cost-effective and more efficient system.

As director of chemical solutions for Goodway Technologies Corp., provider of industrial maintenance solutions, Ray Field is responsible for innovation, product management, and sales strategy for chemical cleaners and descalers. He has more than 22 years of experience in developing and marketing chemical solutions for HVAC water treatment and other markets. He has a degree in chemical engineering and is a certified water technologist.

Did you find this article useful? Send comments and suggestions to Executive Editor Scott Arnold at [email protected].