Page 182 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

Fluid Flow 155

L,. = Latent heat of evaporation of steam at flash pres- q'm = Free air, cubic feet per minute@ 60°F and 14.7 psia
sure, Biu/Ib
R = Individual gas constant= MR/M = 1544/M
l = Horizontal distance from opening to point where
flow stream has fallen one foot, in. Re = Reynolds number, see Figure 2-3
M = ;\,f\,V = molecular weight R 1.1 = Hydraulic radius, ft
l'v!R = Universal gas constant Re = Ratio of compression at entrance of pipe, Figure 2-
n = Number of vertical rises (or hills) in two-phase pipe 37
line flow re= Critical pressure ratio= P'2/P'1
or, n = Polytropic exponent in polytropic gas P-V relation- Sg = Specific gravity of gas relative to air, ( = ratio of mol-
ship
ecular weight gas/29)
P = Pressure, psig; or, pressure drop, P, pounds per 0
square inch, Babcock Equation 2-82) S = Degrees of superheat in a steam condition, degrees
F above saturated (not the actual temperature)
P, = Absolute pressure, torr
s = Steam quality as percent dryness, fractional
Ll.P, = Pressure drop, torr
SpGr = Specific gravity of fluid relative to water at same
P' = Pressure, psi absolute (psia)
temperature
P = Total pressure at lower end of system, psig
0
T = Absolute Rankin temperature, 460 + t, degrees R
Pb, = Barometric pressure, psi absolute
T, == Standard temperature for gas measurement, R =
0
Ps = Total pressure upstream (higher) of system, psig
460 + t
P, = Standard pressure for gas measurement, lbs/sq in.
absolute, psia T 1 = Average flowing temperature of gas, "R
p" = Pressure, lbs/sq ft absolute; (in speed of sound t = Temperature, °F
equation, Equation 2-86), Nole units. L, = Time interval required for the pressure wave to trav-
p' = Gauge pressure, psig el back and forth in a pipe, sec
or, P1 = Initial pressure, in. of mercury absolute, vacuum sys- V = Free air flow, cu ft/sec at 60°F and 14.7 psia
tem
V = Specific volume of fluid, cu ft/lb
Ll.P = Pressure drop, lbs/ sq in, psi; or static loss for flow-
ing fluid, psi V' = Volume, cu ft
Li.Pc = Pressure drop across a control valve, psi Va= Volume, cu fl
Ll.P,-ac = Pressure drop in vacuum system due to friction, in. v = Flow velocity (mean) or superficial velocity in pipe
water/100 ft pipe lines at flowing conditions for entire pipe cross sec-
6.PTPh = Total two-phase pressure drop for system involving tion, fl/sec; or reduction in velocity, ft/sec: (water
horizontal and vertical pipe, psi per fool of length hammer)
Ll.?100 = Pressure drop, pounds per sq in per 100 ft of pipe vm = Mean velocity in pipe, at conditions ofV, fl/min
or equivalent
v, = Sonic (critical) velocity in compressible fluid, ft/sec;
Q = Flow rate, gallons per minute, gpm or speed of sound, ft/sec
Qb = Flow rate, barrels/day vw = Reduction in velocity, ft/sec (actual flowing velocity,
Q 0 == Design flow rate, gpm, or ACFM fl/sec)
Q�. 1 = Maximum flow rate, gpm, or ACFM W = Flow rate, lbs/hr
q = Flow rate at flowing con di lions, c:u ft/sec: Yl\ 11 = Mass flow rate of liquid phase, pounds per hour per
qd = Gas flow rate standard cubic: feel per day, al 60°F square foot of total pipe cross-section area
and 14. 7 psi a ( or 14.65 if indicated); or flow rate, cu \\\ = Mass flow rate, lbs/hr/tube
ft/ day at base conditions of T, and P,
w = Flow rate, lbs/min
qd, = Gas flow at designated standard conditions, cu
ft/day, cfD w, = Flow rate, lbs/sec; or sometimes, VV,
C(h = Gas flow rate, cu ft/hr, at 60°F and 14.4 psiabs, x = Fraction of initial line paralleled with new line
(psi a)
Y = Net expansion factor for compressible flow through
q' = Gas flow, cu ft/sec, at 14.7 psia and 60°F orifices, nozzles, or pipe
q\ = Flow rate al standard conditions ( 14. 7 psi a, and Z = Compressibility factor for gases at average condi-
60°F) cu ft/hr, SCFI-I
tions, dimensionless. Omit for pressure under 100,
qm = Flow rate cu ft/min psig