Page 148 - Boiler plant and distribution system optimization manual

Over 100 Ways to Improve Efficiency 133

ing excess-air requirements (Figure 10.31). The ap- temperature and eliminate to some of the standby
plication of this option depends to a great degree losses.
on existing excess-air levels. This option should
be considered when replacing old equipment or Advantages and Disadvantages
in the design phase of mechanical systems. U. S This option requires additional pressure reg-
Department of Energy tests found an improve- ulating valves and possibly burner modifications
ment in seasonal efficiency from 5.9 to 12.7 per- to produce stepped firing rates.
cent when high speed flame retention head burn-
ers were used on standard heating units.
19. REDUCTION OF FUEL FIRING RATE
Advantages/Disadvantages
This is a small boiler and furnace option. Cost
Flame retention head burners should be specified Low to Moderate
for any new purchases. They may be available
as a retrofit option if the manufacturer has rede- Savings
signed older models. It is a low cost item that can Low to Moderate
reduce excess air.
Description
Conditions change, many burners have been
18. MULTI-STAGE GAS VALVES found to be grossly oversized for their applica-
tions. Successful energy conservation actions,
Cost changes in load requirements and other factors
Low may be producing far less demand for heat. If fuel
firing rate can be reduced, then stack losses will
Saving decrease along with standby losses.
Moderate
Advantages/Disadvantages
Description The cost of installing new burners and the
Gas fired furnaces and boilers having only cost of engineering and other fees for redesign of
one fuel delivery rate can be a disadvantage an existing system may not be justified. A study
which wastes fuel because the only firing rate is of the economics of the issue will show if it will
full fire and off. Having the option of intermedi- pay. It makes no sense to drive a lot of heat into
ate firing rates (high, low and off) can lower stack a boiler with high exhaust gas temperatures and

Figure 10.31—Flame retention head burner.