Revamps 2022 Issue

HAGO PA return to atm. col. (Fig. 3) HAGO prod. from P-21 A/B (Fig. 3)

Vapour to atm. column (Fig. 3)

Crude bypass export

Preash drum

E-23

VTB from P-29 A/B (Fig. 4)

Desalted crude from E-18 A/B (Fig. 1)

E-19 A/B

E-21 A/B

ATB bypass from P-23 A/B (Fig. 3)

E-37 (New)

E-26 A-D

Atmospheric heater

E-22

E-24

E-27 A/B

E-20 A/B

MVGO product

P-12 A/B

Flashed crude to atm. column (Fig. 3) Cooled ATB bypass export

MVGO PA to E-16 A/B (Fig. 1)

E-25

E-30

HAGO product

HVGO product from P-28 A/B (Fig. 4) Heavy diesel product from P-20 A/B (Fig. 3) HAGO PA from P-22 A/B (Fig. 3) MVGO product + PA from P-27 A/B (Fig. 4) Med. diesel PA from P-19 A/B (Fig. 3) VTB quench to vac. column (Fig. 4)

Hvy. diesel product to E-15 A/B (Fig. 1)

HVGO prod. to E-14 A/B (Fig. 1)

Med. diesel PA return to atm. (Fig. 3)

VTB to E-17 A-F (Fig. 1)

Figure 6 Flashed crude preheat train fix-up

flashes to model the transfer line between the vacuum heater and the column to account for the transfer line superheat due to thermal non-equilibrium arising from the stratification of the vapour and liquid, particularly near the column inlet and liquid entrainment in the vapour. This approach provides an adequate amount of wash oil above the minimum wetting rate at the bottom of the wash bed packing, as well as the overflash and realistic estima- tion of the MVGO PA heat duty, which provides a signifi- cant amount of the crude preheat train heat duty matching the actual unit performance. The exchangers in the raw crude, desalted crude, and flashed crude preheat circuits were modelled using the detailed exchanger sizing program within the model. This program allows the user to input the shell and tube side geometry of every exchanger in the preheat circuit, includ- ing the shell side (SS) and tube side (TS) fouling factors.

The design SS and TS fouling factors were adjusted to match the actual exchanger performance during the test run. The results obtained from the program for some of the exchangers were checked against the industry standard exchanger sizing program, such as from the Heat Transfer Research Institute (HTRI), to ensure reliability and accuracy. The actual fouling of exchangers derived from the afore- mentioned formula is shown in Figure 5 . It is apparent that some of the exchangers (E-11, E-12, E-13, E-16, E-18, E-19, E-20, E-21, E-22, E-26, and E-27) are significantly fouled. If parallel bundles are available, these exchangers can be cleaned with the unit online to improve thermal and hydraulic performance and increase the unit throughput. Flashed crude preheat train modification Two simulation models were prepared at slightly higher throughput with new exchanger(s) to debottleneck the

0 10 20 30 40 50 60 70 80 90 100

Design fouling Actual fouling

E-10 A/B E-12 A/B E-14 A/B E-16 A/B E-18 A/B E-20 A/B

E-22

E-24

E-26 A-D

E-28 A-C

E-37

E-11 A/D E-13 A/B

E-15 A/B E-17 A/B E-19 A/B E-21 A/B

E-23

E-25

E-27 A/B

E-29

Figure 7 Fouling of crude preheat train exchangers design vs actual fouling at future throughput

Revamps 2022