Revamps 2026 Issue

Atmospheric distillation unit

Vacuum distillation unit

O-gas

Overhead

LVGO

LN /HN fractionation

LVGO pumparound

Light naphtha

HN /ATF fractionation

Diesel pool

Steam

LVGO / MVGO fractionation

Heavy naphtha

MVGO

ATF pumparound

Steam

ATF / HK fractionation

LDO / MVGO fractionation

Aviation turbine fuel

VGO pool

HK pumparound

HVGO pumparound

HVGO

Steam

Heavy kero

LGO pumparound

Wash section

Diesel pool

SLOP wax

LGO / HGO fractionation

Steam

Light gas o il

Heavy gasoil reprocessed at vacuum column

Crude

Steam

Flash zone

Stripping section

Steam

Atmospheric residue

Vacuum residue

Figure 1 AVU flow diagram – before

CDU to the downstream vacuum column via the heavy vac- uum gasoil (HVGO) pumparound (PA) return stream (see Figure 1 ). It allows recovery of its light portion with the vacuum diesel cut, taken from the top of the vacuum column. The heavy portion is recovered with the HVGO, taken from the middle section of the vacuum column. This practice, while minimising the negative impacts on the downstream unit, introduced unintended systematic penalties at the vacuum tower: • Increased vapour loading to the three beds above the HVGO PA of the vacuum tower. • The light vacuum gasoil (LVGO) PA got overloaded and was close to incipient flooding. • Increased gasoil entrainment to the vacuum distillation unit (VDU) overhead hot-well, placing additional load on the vacuum system. • The desired degree of vacuum could not be achieved anymore. • Poor fractionation between vacuum diesel and medium vacuum gasoil (MVGO). • The pressure drops between the top of the tower and the flash zone increased consistently up to 35 mmHg. • The pressure at the flash-zone increased consistently as well. • The HVGO yield was drastically reduced: it could not be compensated by increasing the coil outlet temperature (COT) of the heater.

• Proportionally to the reduced HVGO recovery, the yield of the vacuum residue (VR) increased. • The front end of the VR became lighter than required. • To meet the required viscosity and penetration of the VR and make it suitable for the downstream bitumen plant, the furnace COT had to be increased up to 410°C, with conse- quent increased operational severity and required energy. These effects collectively constrained crude throughput, increased energy intensity, and imposed additional stress on downstream conversion units. The AVU performance was jointly studied to identify unit bottlenecks and the required modifications to achieve desired distillates yields and qualities while minimising the needed energy. Objectives The refinery established clear operational and commercial objectives to improve performance: u Reduce SRGO slippage into the VGO pool and maximise distillate recovery by: • Improving fractionation between LGO and HGO; before revamp, the overlap was higher than 60°C. • Rerouting HGO directly to the VGO pool, bypassing the vacuum column, by making the front-end of the HGO distil- lation curve heavier, so it is suitable for the VGO pool. v Stabilise VR quality across diverse crude blends (i.e., VG-30 and VG-40 grade bitumen production in high-sul - phur crude). w Reduce VR yield to improve crude-to-distillate conversion.

Revamps 2026