Revamps 2026 Issue

Vacuum furnace COT (˚C)

VGO combined pool 5% (˚C)

420

250 275 300 325 375 350 400

368 372

408 407 408 407 408 408 408 408 407 409

359

407

350 353

350

343 338 340

334 339 332

401 400

325

400

380

Figure 5 VGO 5% (ASTM D1160)

Figure 6 Lower fuel consumption and CO₂ emissions

internals revamp was executed to restore mass-transfer efficiency and reduce energy losses. CDU main fractionator column (11C1) The existing conventional structured packing and liquid dis - tributor were replaced with proprietary High Performance Mellapak Plus packing, along with the liquid distributor in the LGO-HGO section, as shown in Figure 2 . This modi - fication substantially increases fractionation efficiency to reroute heavy gasoil directly to the VGO pool, bypassing the vacuum column. VDU column (12C1) The LVGO pumparound section was upgraded by replacing the existing conventional random packing with Mellapak structured packing and spray distributor, reducing the excessive pressure drop in the LVGO PA and minimising gasoil entrainment to the overhead hot-well. The MVGO/HVGO fractionation bed was removed to reduce pressure drop. This bed became useless now that the diesel is recovered at the CDU main fractionator. The wash-bed packing was replaced with Mellapak Plus and Mellagrid Anti Fouling (MG40 AF) in a sandwich configu - ration. Tie-rods were installed across the wash bed to pre - vent dislodgement during vapour-traffic surges, as shown in Figure 3 . The revamped PFD of the unit (see Figure 4 ) shows all the upgraded sections of the main fractionator and vacuum column, as well as the rerouting of the HCO and MVGO to the VGO pool. Results and benefits The revamp delivered significant gains in separation effi - ciency, product quality, and energy savings: u Distillate recovery: • Incremental increase in diesel yield Y-o-Y by approximately 2 wt%, providing direct refinery margin improvement. v Product separation: • LGO-HGO overlap reduced from 60°C to 30°C (ASTM D86), delivering sharper CDU separation. • HGO recovery at 360°C (ASTM D86) reduced from 45 vol% to ~15 vol%, making HGO heavier and routed to the VGO pool on a consistent basis. This directly indicates a reduction in diesel dropping into the VGO pool. • HVGO 5% (ASTM D1160) and VGO 5% (ASTM D1160)

increased by 20°C, indicating reduced loss of gasoil in VGO, for superior feed quality to the downstream units. • VGO 5% (ASTM D1160, as shown in Figure 5 ). • HVGO 95% (ASTM D1160) and VGO 95% (ASTM D1160) increased, respectively, by 12°C and 10°C, indicat - ing a deeper cut point at the vacuum tower and additional feed for the FCC unit/OHCU. w VR quality and yield: • VR yield reduced Y-o-Y by approximately 2 wt%, increas - ing crude conversion. • Achieved stable VR viscosity and penetration across crude blends, ensuring reliable bitumen production. x Crude throughput flexibility: • Lower VR yield allowed for the debottlenecking of the downstream processing units, enabling the refinery to have a higher and more flexible crude processing slate. y Energy savings: • Vacuum column pressure drop reduced from 35 mmHg to 25 mmHg. • VDU furnace COT reduced by approximately 8°C (from 408°C to 400°C), lowering fuel consumption and CO₂ emis - sions (see Figure 6 ). z Reliability enhancement: • New wash-bed configuration with tie-rod reinforcement eliminated recurring packing dislodgement. • Improved mechanical stability ensured sustained mass-transfer efficiency under varying feed conditions. Conclusion The IOCL Mathura refinery and Sulzer performed a sys - tematic analysis that combined plant-match diagnostics, hydraulic review, mass-transfer evaluation, and strategic hardware upgrades, resulting in noteworthy yield, quality, and energy improvements in the AVU. The 2024 revamp not only enhanced distillate recovery and VR stability but also optimised the operating window, reduced energy demand, and alleviated load on down - stream units. This case demonstrates how targeted inter - nal revamps can unlock significant performance gains in legacy crude-distillation units, especially under diverse and dynamic crude-processing environments. Job execution Sulzer Tower Field Services executed all site activities on a turnkey basis within the timeframe of the planned

Revamps 2026