Page 134 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

118 Applied Process Design for Chemical and Petrochemical Plants

(text continued from page 115) Flow of gases and vapors ( compressible fluids) through
q = cu ft/sec at flowing conditions (Figure 2-37) Coef- nozzles and orifices. (For flow field importance see Refer-
ficient from Reference [22] for liquids discharge ences [31]). From [3]:

r0 = critical pressure ratio for compressible flow, =
P'2/P'1 , 2g ( l 44)6P
q = YC A ' , cu ft I sec
p
(at flowing conditions) (2- 48)

Y = net expansion factor from Figures 2-38A or 2-38B
llP = differential pressure (equal Lo inlet gauge pressure when
.14 discharging to atmosphere)
................ ..... p = weight density of fluid, lbs/cu ft at flowing conditions
-.............. r--..... A = cross section of orifice or nozzle, sq ft
.II C' = flow coefficient from Figures 2-38A or 2-38B
<, ,....__ ............. ... r----.J. ...
........._
r-,...... ! i
---·'° ........ ............. +-, or, W = 1891 Yd 1 C , I =-, lbs/hr (2- 95)
!lP
2
Q.
..... !'-.... ........._ t-r " I vi
..........
Q. ............ � -.. ............. ....... """<
II .!ol ............ r-; -.............. /� " where d, = internal diameter of orifice, in
...... .... .... ........._ ........... i""---.... ....... V1 = specific volume of fluid, cu ft/lb
...........
� ............. � r-; ........... <, 1 I I ..
. 16 r-, -...... ............ - i""'-<.,,
� � <; r-; .. , /ilP P/
•
O f- : -,
.......... .......... , 2
:::::::: � r-....... <, � or, q = 11. 30 Yd C cu ft/sec
___.....
.!>< .... I T1 Sg
""""R � � v' II at 14. 7 psia and 60° F (2- 96)
--- L----"_:
� �
.....,.., _,
.ail where Sg = Sp Gr gas relative Lo air, = mo! wt, gas/29
0
us I.I l.lS l4 I'S Ti= absolute temperature, R
k=Cp/C� P' 1 = pressure, psi abs
P' = psia Procedure
B = ratio small-to-large diameter in orifices and nozzles, A. How to determine fripe size for giuen capacity and pressure
and contractions or enlargements in pipes
drop.
Figure 2-38C. Critical Pressure Ratio, re, for compressible flow
through nozzles and venturi tubes. By permission, Crane Co., Tech- 1. Assume a pipe diameter, and calculate velocity in
nical Paper #410, 1957. Also see 1976 edition. See note at Figure 2- feet/ second using the given flow.
18 explaining details of data source for chart. Note: P' = psia �= ratio
of small-to-large diameter in orifices and nozzles, and contractions or 2. Calculate sonic velocity for fluid using Equations 2-
enlargements in pipes. 84 or 2-85.
,
lt6·INUANT SHARP- $QVAltE RE·ENTRANT 5QtlAllE WELL
TV61 IDtilD IDG£D _J __ w __ ROVNDED
TV/JI
EDGED
! __
J
-,= 1-- -,,- -,-- ....... -+ ___
�-
n- i---
�
1DCrJ1 1/•t.tDIA. ITIIIAM Cl.Ult lll!U UIICT!I • 'L-tl'a DIA. Tlllt IUlnl Fllt
1
C= .52 C= .61 C= .61 C= .73 C= .82 C= .98

Figure 2-39. Discharge coefficients for liquid flow. By permission, Cameron Hydraulic Data, Ingersoll-Rand Co., Washington, N.J., 1979.