The Reliability Files: Proper Training is Key in Evaluating Boiler Upgrades
June 21,
2011
There are several catalysts that can spark a discussion within a company
about whether to upgrade or replace a steam boiler.
The best place to start
the discussion is with people who have been trained in proper boiler operation
and maintenance: They can appreciate the “call to action” signs and
ramifications of a poor decision to modify or replace.
Among the most common reasons for action are: the existence of an old,
outdated boiler; a need to increase fuel efficiency; a requirement to decrease
emissions; a heightened demand for steam; a process-load decrease causing costly
cycling; or escalating maintenance costs on existing equipment.
The age of the boiler system is important to consider, but it should not be
the main factor in the decision-making process. A more critical factor is the
condition of a boiler’s pressure vessel. The shell, furnace and tubes are the
major components in delivering heat energy from the burner into the water.
If an annual inspection of water-side and fire-side surfaces shows minimal
signs of heavy scaling, pitting, cracking or stress, the pressure vessel is most
probably in good shape and can deliver many more years of dependable life.
After determining that the pressure vessel is acceptable, the next step is
calculating the boiler’s efficiency. Using a flue-gas analyzer, check for the
stack temperature over saturated temperature and the percent of oxygen (O2),
carbon monoxide (CO), particulate and nitrogen oxide (NOx) in the exit gas. If
the analysis indicates high excess air (8-10% O2) in the mid- to high-fire
ranges and CO in excess of 50 ppm, the burner will require a major tune-up,
upgrade or replacement. Which is it, though? What if the boiler’s in good shape
but having difficulty meeting load demands? Do you simply add efficiency
upgrades?
Solution
A Midwest food processor recently faced the
above dilemma and had to determine whether to repair or replace its boiler
equipment. The company was running three boilers between 100-300 hp—two of
which were more than 30 years old and coming up short in capacity because of
added load.
The company’s boiler operators and facility engineers—who had been
trained on proper boiler operations and understood the impact of varying and
increasing load conditions—determined that retrofittable efficiency
upgrades to existing equipment would not be able to make up the difference in
needed capacity. A new boiler was, therefore, justified both empirically and
financially, to complement the existing equipment.
Return on Investment
This food processor’s final analysis
was predicated on the assumption that it would have to run one of its older
boilers alongside the new one. As it turned out, the new boiler, with
efficiencies in the high 80s, runs the whole plant—and the old boiler
remains for possible peaking and/or standby duty.
Shutting down the older boilers significantly increased system efficiency and
shortened the projected payback period. In fact, production at this operation
increased 9%, and the plant is using 32% less fuel. Whereas the initial payback
period had been projected to be 51 months, the company now anticipates it will
achieve payback in 32-37 months—and it all started with proper training,
then applying strong operational knowledge and financial tools such as
Cleaver-Brooks’ BOOST analysis test to render a prudent decision.
For a complete listing of Cleaver-Brooks’ training offerings and venues, click here. The objective of all these programs is to help
boiler users improve energy efficiency, system reliability, safety and
environmental sustainability. (CEUs are attached to many of the
courses.)
Cleaver-Brooks
Boiler House
Training Center
Milwaukee, WI
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The Reliability Files: Proper Training is Key in Evaluating Boiler Upgrades