Sq:ft: of coil ¼
47, 824, 000
12, 000
¼ 3, 985:3 sq:ft:
Section 2
Pressure = 335 psia
Six hundred psig steam is introduced into this section of the furnace.
V/L
F
API
lbs/h
Btu/lb
MMBtu/h
In
Feed
L
700
15
351,645
386
135.735
Steam
V
700
35,165
1,383
48.633
Heater duty
By diff
16.652
Total in
201.020
Out
Steam
V
35,165
1,417
49.829
Feed
L
760
15
351,645
432
151.191
Total out
201.020
Section 3
Pressure = 315 psia
V/L
F
API
lbs/h
Btu/lb
MMBtu/h
In
Feed
L
760
15
351,645
386
151.191
Steam
V
760
35,165
1,417
49.829
Heater duty
By diff
22.584
Total in
223.604
Out
Liq feed
L
820
20
344,612
482
165.103
Vap.
V
820
73
7,033
425
2.989
Steam
V
820
35,165
1,440
50.638
Ht. of crack
547
3.874
Total out
386,810
223.604
Cracking begins at a temperature of 800
F and the oil feed and steam
enters the soaking section at 820
. The purpose of the soaking section is to
provide a space for the cracking function to occur at a moderate increase in
temperature. To calculate the required coil volume, the first step is to
assign the degree of cracking that occurs at the end of each section. This is a
trial-and-error process and provides an SVF value to each section which in
turn is used to calculate the amount of cracked products leaving each section.
Using these amounts, the heat balances for each section of the soaker coil are
calculated. Thus:
560
D.S.J. Jones