Page 118 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

102 Applied Process Design for Chemical and Petrochemical Plants

Friction Drop for Flow of Vapors, Gases, and Steam q\ = rate of How, cu fl/hr at standard conditions (14. 7
Figure 2-30 psia and 60°F), SCFH.

A. The Darcy rational relation for compressible flow [3 J is: 1. When calculated Af> total < 10 percent inlet pres-
sure, use p or V based on inlet or outlet conditions.
o. 000335 nv v 2. When calculated LiP total > 10 percent inlet pres-
2
�PI 100 rt = ------ (2-77)
d 5 sure, but< 40 percent, use average p or V based on
inlet and outlet conditions.
2
0.000001959f(q� ) Sg 3. When calculated iiP total, P1 to P2 is> 40% of inlet
2
or, �p I 100 ft= ------------'-- (2-78)
d"p pressure, primarily for long lines, use the following
choices, or break the line into segments and calcu-
The general procedures outlined previously for han-
dling Iluids involving the friction factor, f, and the Re late LiP for each as above.
chart are used with the above relations. This is applicable
to compressible flow systems under the following condi- Also use Babcock formula given in another paragraph
tions [3]. for steam flow.

where Sg = specific gravity of gas relative to air = the ratio of q' h = 24,700 [Yd /Sg] (�P p 1/K) 12, CFH @ 14.7 psia
2
1
molecular weight of the gas to that of air. and 60°F (2-79)
w
1600
p v
AP/100 ft. = 0.000 336 f W2/d5p
1000
50 800
40 600
500
30 400
300
d
20 200
15 2!
s: 100
:::,
0 80
..... 10 1g_ 60 g
0
'-'
:.0 9 - 50 ::: �<>..
8 gi
:::,
c..., f 40 � �
:;; 7�
c,. 6 :.0 .05 30 � '\;
:::,
"' c..., :::,
"C 5 ·= .04 20 &. �
c:
s: 4 ·:; c::, �
:::,
-c"
c::,
...
;::;::: .03 � c::, � -
,,
c:
'ii: � 8 10 ·= es
':I:,"
,S! .....
c
� :c 6 ..... ...
0
0 .OH� 5 0 �
.... ..... 4 .!! �
I
1.s1 .... 3 &l �
1i, .015 I �
u :t: <I
""
1.0·2
.9.,.�
.8 I .01 1
.7 c::,.. .8
.6
.5 .6
.5
.4 .4
.3
.3
.2
.2
.I
Figure 2-30. Pressure drop in compressible flow lines. By permission, Crane Co., Technical Paper #410, Engineering Div. 1957. Also see 1976
edition.