Page 130 - Boiler plant and distribution system optimization manual

Over 100 Ways to Improve Efficiency 115

Advantages/disadvantages
Instruments are often expensive and in them-
selves do not account for any energy savings,
they are however, the only way to find problems.
Manpower that may be needed elsewhere must
be assigned to collect and interpret the data from
field measurements. It’s just good management to
know what is happening with energy, assigning
responsibility for its use and controlling it in a
sensible way

Figure 10.8—Carbon monoxide limit vs. oxygen
3. KEEP BOILERS TUNED-UP
relationship for adjusting controls for optimum
efficiency. Point A is the minimum oxygen control
Description
point, B is the chosen set point based on a buffer zone
A good tuneup, using precision test equip-
for estimated system errors and influences.
ment, can detect and correct excess air losses,
smoking, unburned fuel losses, sooting, fire side
fouling and high stack temperatures.
By using real time instruments to measure
flue gas oxygen, carbon monoxide, carbon di-
oxide, combustibles and temperatures, the cur-
rent state of boiler operation can be diagnosed.
These findings can be used to restore the boiler to
its normal efficient operating condition (Figures
10.1-1 to 10.6). This allows the control system and
burner to be adjusted and repaired for optimum
performance with immediate feedback of results
for gas fuels, (Figure 10.7) and oil (Figure 10.8).
(Figure 10.9) shows the same information for oil
Figure 10.9—Smoke limit (dashed line) vs. oxygen
and coal based on smoke limit criteria. When a
relationship for adjusting controls for optimum
efficiency on oil and coal fired plants. In this case
point A is minimum oxygen control point. Point B
is the chosen set point based on the estimated buffer
zone needed to compensate for control system errors
and other outside influences affecting combustion.

tune-up is completed there should be a good re-
cord of a boiler’s excess air and efficiency across
the load range for managing boiler operations.
After the initial tune-up, recheck results un-
til assured that the boiler can stay tuned-up for
a reasonable amount of time. Tune-ups may be
Figure 10.7—The carbon monoxide vs. oxygen needed more than twice a year. Periodic checks
relationship showing CO control range and operating will tell the story; often boiler efficiency will fall
range for highest efficiency. by over 5% within 6 months or sooner.