Design Guidelines for High Performance Industrial Furnaces - High Temperature Air Combustion: From Energy Conservation to Pollution Reduction - page 319

η = unit consumption

Tj = average temperature rise of j th element

t = operating time

6. Heat loss by cooling water H loss

H loss = η c water ∆ t water ∆ t

η = unit consumption

c water = specific heat of water

t water = temperature difference of water

t = heating and soaking time

7. Other losses (6) × 10%
8. Total heat capacity H total loss = (6) + (7)

H total loss = 1.1 η c water ∆ t water ∆ t

9. Total combustion amount Q comb

η
η

== () =

H

viii

η 1. c T t

total loss c water water

c

η = efficiency of combustion

c

10. Unit fuel consumption Q fuel consumption

Q fuel consumption = H total loss / M coils

M coils = weight of coils

e. Positions of fans in furnace: the positions of fans can be determined
by the rule of geometrical similarity with the test furnace.
f. Capacity of fan: the ratio of region downward from the total volume
of wind generated by the fan was confirmed to be 0.39 under the actual
data of wind rate distribution, as shown in Figure 5.76 . The capacity
of the fan can be decided by the assumption that half of the total volume
of wind generated by fan flows into the region. The capacity of the fan
Q m 3 /min can be expressed by Equation 5.12.

Q = AV av · 60 (5.12)

where A [m 2 ] is the shaded area in Figure 5.77 , and V av [m/s] is the
average wind rate around the coil equal to that of the test furnace.