Example 112

An example of the interaction coefficient method spreadsheet for a multicomponent blend follows. We want to determine the RON, MON, and ASTM distillation of a blend of these components:

FCC light naphtha (LCN) FCC medium naphtha (MCN) Light straight run (LSR) Polymer gasoline (POLY) Reformate 95 RON (REF 95) Reformate 97 RON (REF 97)

The following properties are determined in the laboratory for each of the blend components and for all possible binary blends: RON, MON, and ASTM distillation; percent evaporated at 150°, 195°, 250°, and 375°F.

The number of binary blend components determines how many binary blends are possible. Hence, for a six-component blend, 15 binary blends are possible. All the 15 binary blends are made in the laboratory and their properties determined for computing the interaction coefficient for each binary blend. Once the binary interaction coefficients are known, the properties for any blend composition can be determined by means of the blending equation. The calculations are facilitated by means of a spreadsheet program.

The properties of the pure components and all binary blends interaction coefficients are shown in Tables 11-3 to 11-6. To calculate the properties (RON, MON, distillation) of the blend, the blend composition is entered in Table 11-6 and the blend properties are read from Table 11-7.

Table 11-3 Blend Component Properties

COMPONENT

LCN

MCN

LSR

POLY REF 97 BUTANE

DENSITY

0.70

0.75

0.68

0.73

0.79

0.57

VAP. PRESSURE

psia

9.1

2.6

9.7

9.1

6.7

65.3

ASTM DISTILLATION

VOL% EVAPORATED

IBP

°C

37.0

53.0

36.0

33.0

38.0

0.0

@ 60°C

24.5

0.0

31.0

8.0

8.0

100.0

@ 65°C

32.5

0.5

41.0

10.0

11.0

100.0

@ 80° C

51.0

4.0

66.0

14.5

18.5

100.0

@120°C

88.0

55.0

100.0

50.0

40.0

100.0

@190°C

100.0

100.0

100.0

91.5

98.5

100.0

FBP, °C

158.0

153.0

117.0

230.0

191.0

0.0

HA ANALYSIS

SATURATES

Vol %

48.8

47.7

96.4

5.2

46.5

0.0

OLEFINS

Vol %

44.6

39.0

0.1

94.1

0.6

0.0

AROMATICS

Vol %

6.6

13.3

3.5

0.7

52.9

0.0

SULFUR

% WAV

0.0

0.0

0.0

0.0

0.0

OCTANE NUMBER

RON

89.6

84.0

55.2

97.5

97.2

87.1

MON

78.5

75.9

55.0

82.9

87.1

87.0

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