Retrotec USACE - Manual (Page 259)

Appendix D D129
stored above ground (Figures D209 and D210), can be atomized in all but the
very coldest temperatures. Fuel oil grades number 4 and higher need preheat-
ing before burning, with the following recommended temperatures:
No. 4 57 °C (135 °F)
No. 5 85 °C (185 °F)
No. 6 99 °C (210 °F)
This is a good application for a heat recovery system.
D.7.8.18 Heated Cooling Water Is Wasted (Waste)
Figure D211. Water-cooled heat treat ovens.
High-temperature furnaces that heat metal are often water-cooled (Figure
D211). Water fl ows through the furnaces shell to keep the hot inside tem-
peratures from destroying the walls and roof. This water is then normally
sent to a cooling tower to expel the heat to the atmosphere. The recovery
of heat from this warm water may be an application as a source of heat for
a nearby process such as a parts washer or could be used to heat domestic
hot water.
D.7.8.19 Use of Underfi red Heaters (Ineffi ciency)
The production demands of industrial shops can change, but the equipment
is seldom replaced with more appropriately sized units. As a result, oversized
production equipment is used for necessary operations. This requires heating
up large furnaces even to temper only a few parts. This approach results in a
waste of energy.