Page 172 - Improving Machinery Reliability

144 Improving Machinery Reliability

Approximation for S':
S' = R [l - cos 0 + (R sin2 0) 124, where
stroke 12
R = 1 / 2 stroke, and R / 2e = ratio
connecting rod length
8 = crank angle, starting at inboard zero reference

k
l+E during compression stroke
= ps (1 + E - S'I s)
k'
during expansion stroke

2. Determination of maximum gas force in a representative first stage.
PD - Ps = 2,000 - 300 = 1,700 kg/cm2 (= net effective pressure)
Plunger diameter =9cm
(z)(81>
Plunger area - = 63.8 cm2
4
Net effective plunger force = (1,700) (63.8) = 108,200 kg
3. Determination of maximum gas force in a representative second stage.
PD - Ps = 3,600 - 1,750 = 1,850 kg / cm2 (= net effective pressure)
Plunger diameter =8cm
(M64)
Plunger area ___ = 50.3 cm2
4
Net effective plunger force = (1,850) (50.3) = 93,000 kg
4. Inertia load contribution during time of maximum gas load. Here we are using
crank angle 0 = 260", 80" + 180"-a typical arbitrary example. In Figure 3-39:
X = C,A - CA, CA = CD + DA
+
C,A = e + R, CA =e COS 0 R COS 8
X =e + R - e COS 0 - R COS 8
h = e sin 0 = R sin 8
sin 0 (R sin 0) / e, cos 0 = JI - sin2 0
=

X = C+ R - 41 - (R2sin2 0/P2 - R cos 8
Using binomial theorem expansion
n(n-1) an-2 2
b k....
2!
Le. (a rf: b)" = a" f na"-'b + I__