Boilers Case Studies
Boiler Maintenance and its Impact
A 300-hp boiler installed at a public school in Canada was valued at about $100,000. After a maintenance worker noticed water dripping from a steam valve, the boiler was shut down for inspection. During the inspection, insulation was removed. The boiler inspector concluded that water had been leaking into the insulation for so long that corrosion had developed completely around the boiler. The inspector could actually penetrate the boiler with a pocket knife. The boiler was a total loss — yet less than $5 worth of packing for the valve, applied at the right time, would have saved the boiler.
Lesson Learned
Operators and maintenance technicians must conduct a visual inspection of a boiler, especially during start-ups and running operations. Maintenance personnel must follow and perform all maintenance requirements, per manufacturer requirements. Operators must report any anomalies as soon as possible, so they can be taken care of before the problem grows beyond repair.
Combustion Efficiency of a Natural Gas Boiler
A study of combustion efficiency of a 300 hp natural-gas-fired heating boiler was completed. Flue gas measurements were taken. The temperature was 400°F and the oxygen level was 6.2%. An efficient, well-tuned boiler of this type and size should have a percent oxygen reading of about 2% — corresponding to about 10% excess air. This extra oxygen in the flue gas translates into excess air (and its heat) traveling out of the boiler system — a waste of energy.
The calculated savings from bringing this boiler to the recommended oxygen/excess air level was about $730 per year. The cost to implement this action included the purchase of an inexpensive combustion analyzer costing $500. Thus, the cost savings of $730 would pay for the implementation cost of $500 in about 8 months. Added to these savings is the ability to tune other boilers at the site with this same analyzer.