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Among the most common reasons for action are: the existence of an old, outdated boiler; a need to increase fuel efficiency; a requirement to decrease emissions; a heightened demand for steam; a process-load decrease causing costly cycling;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?
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.
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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.)
Boiler House Training Center