Page 286 - Pipeline Rules of Thumb Handbook

Gas—Compression 273

13 Calculate discharge volumetric efficiency using Equation
P % = 10 P line (12)
13:
Where a detailed pulsation analysis is required, several
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1
.
.
approaches may be followed. An analog analysis may be per- E vd =¥[0 823 ] [1 617 11 28 ]
formed on the Southern Gas Association dynamic compres- = 0 565
.
sor simulator, or the analysis may be made a part of the
compressor purchase contract. Regardless of who makes the Calculate volume displaced per revolution using Equation
analysis, a detailed drawing of the piping in the compressor 1:
area will be needed.
The following equations are intended as an aid in estimat- PN =[ S t ¥ 3 1416 ¥ D ] [1 728 ¥ ] 4
2
.
,
d
ing bottle sizes or for checking sizes proposed by a vendor =[5 ¥ 3 1416 ¥ ] [1 728 ¥ ] 4
2
,
.
9
for simple installations—i.e., single cylinder connected to a
.
header without the interaction of multiple cylinders. The = 0 184 cu ft or 318cu in.
bottle type is the simple unbaffled type.
Refer to Figure 3, volume bottle sizing, using volu-
metric efficiencies previously calculated, and determine the
multipliers.
Example. Determine the approximate size of suction and Suction multiplier = 13.5
discharge volume bottles for a single-stage, single-acting, Discharge multiplier = 10.4
lubricated compressor in natural gas service.
Discharge volume = 318 ¥ 13.5
Cylinder bore = 9in. = 3,308cuin.
Cylinder stroke = 5in.
Rod diameter = 2.25in. Suction volume = 318 ¥ 10.4
Suction temp = 80°F = 4,294cuin.
Discharge temp = 141°F
Suction pressure = 514psia Calculate bottle dimensions. For elliptical heads, use
Discharge pressure = 831psia Equation 14.
Isentropic exponent, k = 1.28
Specific gravity = 0.6 Bottle diameter d b = 0.86 ¥ volume 1/3 (14)
Percent clearance = 25.7%
Volume = suction or discharge volume
Step 1. Determine suction and discharge volumetric effi-
ciencies using Equations 5 and 13. Suction bottle diameter = 0.86 ¥ 4,294 1/3
= 13.98in.
E vd =[ E v ¥ ] 1 k
(13)
f r p
Discharge bottle diameter = 0.86 ¥ 3,308 1/3
r p = 831 514 = 12.81in.
.
= 1 617
Bottle length = L b = 2 ¥ d b (15)
Z 1 = 0.93 (from Figure 4, page 199)
Suction bottle length = 2 ¥ 13.98
Z 2 = 0.93 (from Figure 4, page 199) = 27.96in.

.
.
f = 093 0 93 Discharge bottle length = 2 ¥ 12.81
= 25.62in.
.
= 10
Calculate suction volumetric efficiency using Equation
5:
Source
[
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1
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E v = 0 97 - (1 1 ) ¥ (1 617. ) 11 28 - ] ¥ 0 257 0 03 Compressors—Selection & Sizing, Gulf Publishing Company,
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.
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= 0 823 Houston, Texas.