ENERGY AND FURNACE DESIGN FOR BATCH ANNEALING AND HEAT TREATING FURNACES.

Energy consumed by the newer direct fired recuperative system amounts to approximately 0. 85 MM Btu/ton. This compares with approximately 1. 2 MM Btu/ton for many existing radiant tube furnaces. A savings of 30 to 40% can be achieved by converting the radiant tube furnaces to direct fired recuperative systems. In the direct fired recuperative furnaces, 52% of the fuel input goes to direct heating of the steel vs. only 35% for the cold air radiant tube fired furnace. This occurs through improved heat transfer from direct firing and greatly reduced flue gas temperature from recuperation. Examples represent two specific areas of furnace equipment in a steel mill.