Chapter 6 — Adjustment Procedures
Part No. 750-184 6-17
Note: All adjustment should be done by a qualified boiler
operator or your local Cleaver-Brooks Service
representative.
Burner efficiency is measured by the amount or percentage of O
2
present in the flue gas. O
2
readings determine the total amount or
excess air in the combustion process, above the point of
stoichiometric combustion or perfect combustion. Stoichiometric
combustion is a term used to describe a condition when there is the
exact amount, molecule for molecule, of air for the fuel attempting
to be burned. This can be accomplished under laboratory
conditions, however it’s not practical to attempt to meet this
condition in a boiler. Stoichiometric combustion however, is the
reference point used when setting fuel/air ratios in a boiler.
There must always be excess air in the combustion process to
account for changes in boiler room temperature and atmospheric
conditions, and to ensure the combustion is on the proper side of
the combustion curve.
Proper setting of the air/fuel ratios at all rates of firing must be
established by the use of a combustion or flue gas analyzer. The
appearance or color of the gas flame is not an indication of its
efficiency, because an efficient gas flame will vary from transparent
blue to translucent yellow.
Most flue gas analyzers in use today measure the content, by
percentage of oxygen (O
2
) and carbon monoxide (CO) either by
percent or parts per million (ppm). Carbon dioxide (CO
2
) is not
normally measured with todays flue gas analyzers, but may be
displayed via a calculation.
The O
2
levels through the entire firing range of the burner, low fire
to high fire should be tested. The burner manufactures
recommendations on turndown should also be followed and the
turndown range of the burner should not be exceeded.
To Next Page
Loading...