Vacuum Distillation Unit

The reduced crude from vacuum heater H-102 enters the flash zone of vacuum tower V-104. The column operates under vacuum by means of an ejector/condenser system to achieve the required separation between the heavy components at lower temperature. Some gaseous hydrocarbons are produced due to cracking of the feed in vacuum heater H-102. This sour gas is burnt in atmospheric tower heater H-101 while the condensate water is routed to desalter feed water surge drum V-106.

The tower is provided with a cold recycle (quench) to lower the bottom temperature and avoid coking. A superheated stripping stream is introduced at the bottom of the tower. The heavy diesel product is drawn as a sidestream and exchanges heat with crude oil in the preheat train. It is partly used as top and intermediate reflux to the column, and the balance is sent to storage after cooling in E-121 and E-113.

VACUUM FURNACE

REDUCED CRUDE FROM P-107

HEAVY VACUUM STEAM STEAM

GAS OIL STRIPPER EJECTOR EJECTOR V-107 EJ-101 EJ-102

OILY CONDENSATE FOUL WATER

SURGE DRUM STRIPPER

v-ioa v-109

VENT TQ H-1C1

FOUL WATER STRIPPER OVKD ACCJLLIMATOR

H'102 I ! 1S0PSIG

J v STEAM

VENT TQ H-1C1

Crude Oil Vacuum Gas Stripper Image

> OILY WATER OILY WATER

FROM OILY TO

CONDENSATE DESALTERS DRUM

> OILY WATER OILY WATER

FROM OILY TO

CONDENSATE DESALTERS DRUM

V-107 CRU0E

V-107 CRU0E

Overhead Reflux Drum Ventilation

HEAVY VACUUM GAS OIL

VACUUM BOTTOM

Figure 1-5. Vacuum distillation unit. C.W. = cooling water; OVDH = overhead.

HEAVY VACUUM GAS OIL

VACUUM BOTTOM

Figure 1-5. Vacuum distillation unit. C.W. = cooling water; OVDH = overhead.

Vacuum gas oil drawn as bottom sidestream is stripped in steam stripper V-107 and cooled by exchanging heat with crude in the preheat train and finally in air cooler E 114 and trim cooler E-126 before being sent to off-site storage tanks.

The bottom product, the vacuum residue, exchanges heat with crude coming from the preflash tower bottoms and in the preheat train before being sent to off-site storage.

To control corrosion, a 3% ammonia solution and inhibitor is injected into the top of preflash, atmospheric, and vacuum towers.

Foul water is generated in the overhead accumulator drum of atmospheric distillation column and in the ejector/condenser system of the vacuum distillation column. All foul water streams are combined in oily condensate surge drum V-108. From V-108, the oily water is transferred by P-118 to foul water stripper V-109. Superheated steam is admitted at the bottom of this 12-plate tower for stripping H2S and NH3 from the foul water.

The overhead gases are cooled and condensed in air fin cooler E-118. Noncondensable gases are routed to the flare header. Condensed and concentrated H2S/NH3 liquid is returned to the column as total reflux. The hot stripped water from the column bottom is partly recycled to desalters and the rest is to a water treatment plant.

The typical operating conditions for an atmospheric and vacuum distillation towers are shown in Tables 1-5 through 1-7.

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