Page 287 - Mechanical Engineers' Handbook (Volume 4)

276 Furnaces

water-cooled load supports and better maintenance of insulation, proportioning temperature
control rather than the two position type, and higher preheated air temperatures. For inter-
mittent furnace operation, the use of a low-density insulation to line furnace walls and roofs
can result in substantial savings in fuel demand for reheating to operating temperature after
idle periods.
The relative costs and availability of gas and oil fuels may make a switch from one fuel
to another desirable at any future time, preferably without interrupting operations. Burner
equipment and control systems are available, at some additional cost, to allow such change-
overs.
The replacement of existing furnaces with more fuel-efficient designs, or the improve-
ment of existing furnaces to save fuel, need not be justified in all cases by direct return on
investment. Where present plant capacity may be reduced by future fuel shortages, or where
provision should be made for increasing capacity with fuel supplies limited to present levels,
cost savings by better fuel efficiency may be incidental.
Government policies on investment tax credits or other incentives to invest in fuel-saving
improvements can influence the return on investment for future operation.

REFERENCE
1. C. Cone, Energy Management for Industrial Furnaces, Wiley, New York, 1980.