PTQ Q2 2024 Issue

Main fractionator

512

500

Prefractionator T 1

510

511

581

502

Z414_S17

501

Feed

408

S14

Z414_C11A

529

Z414_C11B

Figure 5 Process simulation model as per Petlyuk configuration

column models the section of the column equipped with the partition baffle and facing the feed, also called the pre - fractionator. The second column models three sections, from top to bottom: the section of the column above the partition baffle; the section of the column equipped with the partition baffle and facing the middle-cut draw-off; and the section of the column below the partition baffle. This second column is also known as the main fractionator. This second model is also known as the Petlyuk 6 configuration, in honour of the author who first studied and discussed this topic in detail in 1965. At Sulzer, Petlyuk‘s model is preferred. In addition, an in-house optimised model has been developed. It allows for a fast, solid, and reliable convergence of the process sim - ulation. The output results can be automatically imported into a dedicated hydraulic rating tool for the design of mass

transfer components and associated tower internals of a DWC. It must be underlined that this is the most critical step while designing a DWC. The offset location of the dividing wall to the axe of the column and the mass transfer com- ponents at the right and left of the baffle should be prop - erly designed to achieve the performance of the tower, as expected from the process simulation model. Ideally, the pressure drop at the left and right of the baf - fle will be the same so that the vapour coming from the section below the baffle will split between the prefraction - ator and the main fractionator, as expected by the process simulation model. In real life, this may not be possible due to the required operational flexibility, not only in terms of operating range (110-50% of design capacity) but also in terms of cases with different feed composition and or

Heavy Naphtha 79 , 781 834.2

Middle Naphtha 160 , 000 804.4

Light Naphtha 90 , 219 762.3

Kg/h 330 , 000 Feed Flow rate Density Kg/m 799.2

103

1.2

0.8

D 86 % vol IBP

Light naphtha to SCAN finer

1.3

˚C 175.7 ˚C 184.8 ˚C 198.0 ˚C 150.0 ˚C 126.5 ˚C 70.6 ˚C 86.4 ˚C 90.7 ˚C 105.0

201.5 208.3 214.6 187.2 178.8 144.7 157.2 163.5 172.1

159.2 165.6 181.0 143.6 131.9 110.5 113.7 115.6 122.4

84.9 89.0 97.2 78.9 74.3 52.2 63.7 67.4 70.7

16.5

Middle naphtha to U nionning/ P latformer

90 95 70 50 10 30

138

161

Pressure kg/cmg

Temperature ˚C

FBP

Duty MMKcal/h

ex41

-8.4

24.7

GAP

˚C

1.5

217

Heavy naphtha to SCAN finer

Figure 6 Material balance and main operating data after revamping

PTQ Q2 2024