Fluid_Flow_Rules_of_Thumb_for_Chemical

18

Rules of Thumb for Chemical Engineers

Example sketch

Mw = Gas molecular weight P1,P2 = Inlet and outlet line pressures, psia Pc r i t - Critical pressure for sonic velocity to occur, psia T = Absolute temperature, ~ W = Gas flow rate, lb/hr Z - Gas compressibi l i ty factor

psv set @ 110 psig x 1.1 accumulation = 121 psig = 136 psia

/ .

/ .

15 psia

l

NC ~[

]

60 ~ 1O0 psig

Sources

lin

0

1. Mak, Henry Y., "New Method Speeds Pressure-Rel ief Manifold Design," Oil and Gas Journal, Nov. 20, 1978, p. 166. 2. API Recommended Practice 520, "Sizing, Selection, and Installation of Pressure Rel ieving Devices I Refineries," 1993. 3. "Flow of Fluids through Valves, Fittings, and Pipe," Crane Co. Technical paper 410, 1981. 4. Crocker, Sabin, Piping Handbook, McGraw-Hi l l , Inc., 1945. 5. Standing, M.B. and D. L. Katz, Trans. AIME, 146, 159 (1942).

200 equiv, ft

C1

300 psig = 315 psia 60 ~

Nomenclature

D = Pipe diameter, ft d - Pipe diameter, in f = Moody friction factor L = Line equivalent length, ft M1,M2 = Mach number at the line inlet, outlet

CompressibleFlow--Long Pipelines

Equations CommonlyUsed for Calculating Hydraulic Data for Gas Pipe Lines

Weymouth.

0.5 Q- 433.5x (Yb/Pb)XI p12GLTz-p22 I X D2"667 x E

Panhandle A.

Qb 435.87 x (TB/PB)1"0778 D2.6182 - x x E x

Pavg -- 2/3[P~ + P2 - (P1 x P2)/1:'1 + P2]

pl 2 _ p2 2 _ 0.0375 x G x (h2 - hi) M Pavg2 0.5394 Tavg X Zavg 6 0.8539 • L x Tavg x Zavg

Pavg is used to calculate gas compressibi l i ty factor Z

Nomenclature for Panhandle Equations

Qb = f l ow r a t e , SCFD P b - base pressure, psia Tb " - b a s e temperature, ~ Tavg = average gas temperature, ~

Panhandle B.

P1 = inlet pressure, psia P2 - outlet pressure, psia G = gas specific gravity (air = 1.0) L = line length, miles Z = average gas compressibi l i ty D = pipe inside diameter, in. h2 - elevation at terminus of line, ft

Qb 737 X (Tb/Pb)L~176 - X D 2s3 • E

_ 0.0375 x G x (h2 - hi) x Pavg2 0.51

pl 2 _ p22

Tavg X Zavg 6 0"961X L x Tavgx Zavg

x