Page 179 - Applied Process Design For Chemical And Petrochemical Plants Volume III

66131_Ludwig_CH10E 5/30/2001 4:33 PM Page 142

142 Applied Process Design for Chemical and Petrochemical Plants

Condensing Surface Area 134.652115.35215202
v 0.0835 lb>ft 3
13792114.70215942
1
U o
1 1
r i 1d o >d i 2 r t r o
Shell-Side P
h io h o
1
R e 12,070, previous calculation, from Figure 10-140
1 1
0.00111.25>0.8752 0.000368 0.0015 f 0.00205
436 445
1 2
U o 127.6 Btu>hr 1ft 21°F2 f s G s D s ¿1N c 12
2
0.00783 p s
2g D e ¿
s
Area: A Q>U t
where
1227,0002 Number of baffles 22
A 24.9 ft 2 8
1127.62171.502 g 4.17 10
2
G s 307,000 lb/hr (ft )
D e 0.0886 ft
Sensible Gas Cooling Area
25
D s 15. / 12 1.27 ft
L 62.27 lb/ft 3
1
U o
s essentially 1.0
1 1
0.001428 0.000368 0.0015
7.84 445 2
10.0020521307,0002 11.272122 12
p s
1 1834,000,0002162.27210.08862
U o
0.1275 0.001428 0.000368 0.0015 0.002245 p s 1.23 psi; use 2.25 psi for system allowances
1
U o 7.51
0.133041 Note that this pressure loss does not account for nozzle
entrance or exit losses. These losses may be neglected pro-
125,300 6,2002
Area: A 58.7 ft 2 vided velocities are low and no unusual conditions are
17.512171.502
imposed upon these connections. For low pressure systems,
these losses cannot be ignored.
Total Area
A 24.9 58.7 83.6 ft 2
Tube-Side Pressure Drop
“Safety Factor,” or excess area:
% S.F. with unit containing 157 ft 157/83 .6 1.878 87.8%
2
R e D G t / v
gas @ 114°F: 90.25 mol % HCI in feed, 99.7 wt. % exit
This is normally too large a value to be considered an eco-
Avt. wt. % HCI 95.0 wt. %
nomical design. However, in this case, future flow rates indi- (0.950) (0.0150) (1 0.950) (0.0105)
cate that the 157 ft will be close to the needed area. Rather 0.01478 centipoise
2
than handle and provide piping and special valves for two 0.0358 lb/ft hr
units, it is cheaper and easier from an operation viewpoint
to install one large unit at this time. 10.07292113,5602
R e 27,650
10.03582
Overall U Calculation
f 0.000204 (Figure 10-137)
258,500
U 43.2 10.0002042113,5602 162122
2
183.62171.502 p t 0.089 psi
1221417,000,000210.0831210.07292
Overall U Used (Based on the Over-Sized Unit) v at 114°F and 1 atm 0.0831 lb/ft 3
1258,5002
U 23.0 For bundle entrance and exit losses, refer to copyrighted
11572171.502 graph of Donohue. 38
Density Avg. Vapor Flow @ Avg. Temperature of 134°F 0.65 psig p r (0.051) (2) 0.102 psi
p tt calculated total 0.089 0.102 0.191 psi
Avg. MW vapor @ inlet and exit avg. conditions 34.65 p tt used (0.191) (1.2) 0.23 psi