Page 309 - Introduction to Petroleum Engineering

298 MIDSTREAM AND DOWNSTREAM OPERATIONS

will split into gas and liquid phases. Verification of these checks is left as an
exercise at the end of the chapter.

Component Feed (z ) k‐Value z k z /k
i i i i i
n‐C H 12 0.20 6.77 1.35 0.03
5
n‐C H 18 0.20 0.898 0.18 0.22
8
n‐C H 26 0.20 0.101 0.02 2.0
12
n‐C H 34 0.20 0.0162 0.003 12.3
16
n‐C H 0.20 0.00337 0.0007 59.3
20 42

Example 15.3 Flash Calculation at 330°F
Complete the flash calculation for the five‐component system of the previous
examples at 45 psia and 330°F.

Answer
Use the kernel of the sum in Equation 11.9 to calculate mole fractions for the
liquid phase for a chosen value of G. Vary G until the sum of liquid mole frac-
tions equals unity. Results are listed in the following table for G = 0.123. Use
Equation 11.5 to calculate the gas phase mole fractions. Verification of these
results is left as an exercise at the end of the chapter.

Component Feed (z ) k‐Value x y
i i i
n‐C H 12 0.20 6.77 0.117 0.791
5
n‐C H 18 0.20 0.898 0.202 0.182
8
n‐C H 26 0.20 0.101 0.225 0.022
12
n‐C H 34 0.20 0.0162 0.228 0.004
16
n‐C H 0.20 0.00337 0.228 0.001
20 42

Example 15.4 Flash Calculation at 600°F
Perform a flash calculation for the five‐component system of the previous
examples at 45 psia and 600°F.

Answer
Although the steps of both Examples 15.1 and 15.2 are needed, just the results
corresponding to Example 15.3 are shown in the following for a chosen value
of G = 0.841. Verification of these results is left as an exercise at the end of the