Refining India December 2025 Issue

Minimum potential furnace duty 57 MW from 70 MW

Current furnace duty 70 MW

360

330 300 270 240 210

180 330 300 270 240 210

57 MW

20˚C

Enthalpy (MW)

180

150

120

Cold current temperature Hot temperature Cold pinch temperature

Minimum potential cooling duty 54 MW from 68 MW

0.00 30.00 60.00 90.00 90.00 150.00 180.00 210.00 240.00

Enthalpy (MW)

Figure 4 Temperature-enthalpy diagram and the Grand Composite Curve of the crude preheat train in case study with an approach temperature of 20°C

• Strategically plan upstream cleaning activities, knowing that restored exchanger performance upstream would reduce the downstream cooling burden and fan power demand. Case study 3: Pinch analysis In this case study, a 127,000 bbl/day crude preheat train with a furnace duty of 70 MW and an approximate CO 2 emission of 320 tonnes/ day ( Kemp, 2007 ) is modelled. Despite multiple exchangers recovering heat from product and intermediate streams, the system still relies heavily on the furnace. SmartPM’s composite curve tools reveal that the current design operates significantly above the thermodynamic minimum utility requirement. The plant model is analysed to compare existing performance with pinch- compliant configurations. The composite curves show a cold curve that begins well below the hot curve – evidence of unexploited heat recovery. The Grand Composite Curve (see Figure 4 ) identifies a potential 13 MW reduction in furnace duty, from 70 MW to 57 MW, if the heat exchanger network were fully optimised. However, ideal optimisation is rarely feasible in practice due to: • Limited space for new exchangers. • Inflexible piping configurations. • Budgetary constraints. • Turnaround and project timing limitations. SmartPM’s exchanger inefficiency analysis (see Figure 5 ) revealed several actionable findings:

• Streams 1, 2, and 3 : Heat is transferred from above the pinch to below, violating pinch rules and unnecessarily increasing furnace load. • Stream 4 exchanger : This unit was strategically moved downstream (post-flash column), freeing up exchanger locations for improved placement of streams 1-3. • New exchangers: New units were added below the pinch to maximise recovery without introducing pinch violations. This strategy avoids complex cold stream splitting and instead realigns exchanger duties to comply with thermodynamic constraints. Resulting benefits include: • Furnace load reduction of ~7 MW. • CO₂ emissions reduction >10%. • Cooling load reduction due to improved internal heat recovery. This compromise captures most potential energy savings while respecting physical constraints. SmartPM implementation pathway To fully unlock the benefits of SmartPM, a structured, phased implementation strategy ensures accuracy, reliability, and user engagement:  Model construction : The first step involves defining the scope of the digital twin project. This could focus on a specific section of the plant, such as a crude preheat train or a fired heater. It is essential to gather detailed exchanger geometry and operational parameters, as well as accurately tag process stream IDs. HTRI provides support to

Refining India