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The present study evaluates the technical and economic feasibility of recovering vented vapour from the Bayer circuitBayer circuit (evaporation, precipitation, and digestionDigestion steps) and calcinationCalcination as a decarbonisation strategy for aluminaAlumina refining, using Aspen Plus, compared with conventional natural gas boilers. Results show that 100% of steam supply for Bayer circuitBayer circuit usage can potentially be met via internal recovery: 43% from calcinationCalcination (H2 in oxygen‑steam combustion), 9% from digestionDigestion, 37% from evaporation, and 11% from precipitation. An estimated 79% reduction in energy consumptionEnergy consumption for steam supply is plausible with full (100%) steam recoverySteam recovery, relative to steam generation from gas boilers. Economically, compared with boilers at a gas price of 7.5 US$/GJ including a cost of carbon capture and storage (CCSCarbon Capture and Storage (CCS)) of 179 US$/tCO2, the full steam recoverySteam recovery scenario is estimated to reduce the levelised cost of decarbonised steam for the Bayer circuitBayer circuit (LCOSB) by 50% at a fixed 70 US$/MWh electricity price, dropping from 110.2 to 55.1 US$/tAl2O3. The capital cost of multi-stage mechanical vapour recompression (MVR) is the dominant component (50%) of the LCOSB in this scenario, while renewable electricity remains the primary operating cost driver. A sensitivity analysis indicates that, with natural gas at 7.5 US$/GJ and no CCSCarbon Capture and Storage (CCS), cost parity is achieved when electricity prices fall below 60 US$/MWh; with CCSCarbon Capture and Storage (CCS), electricity-based steam recoverySteam recovery is cost-competitive for costs above 30 US$/MWh.

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Optimisation of Steam Recovery from Calcination and the Bayer Circuit Using Multi-stage Mechanical Vapour Recompression

  • 会议论文

  • 发表日期：

    2026年

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  • Siyun Ning,
  • Graham Nathan,
  • Peter Ashman,
  • Woei Lean Saw

摘要

The present study evaluates the technical and economic feasibility of recovering vented vapour from the Bayer circuitBayer circuit (evaporation, precipitation, and digestionDigestion steps) and calcinationCalcination as a decarbonisation strategy for aluminaAlumina refining, using Aspen Plus, compared with conventional natural gas boilers. Results show that 100% of steam supply for Bayer circuitBayer circuit usage can potentially be met via internal recovery: 43% from calcinationCalcination (H2 in oxygen‑steam combustion), 9% from digestionDigestion, 37% from evaporation, and 11% from precipitation. An estimated 79% reduction in energy consumptionEnergy consumption for steam supply is plausible with full (100%) steam recoverySteam recovery, relative to steam generation from gas boilers. Economically, compared with boilers at a gas price of 7.5 US$/GJ including a cost of carbon capture and storage (CCSCarbon Capture and Storage (CCS)) of 179 US$/tCO2, the full steam recoverySteam recovery scenario is estimated to reduce the levelised cost of decarbonised steam for the Bayer circuitBayer circuit (LCOSB) by 50% at a fixed 70 US$/MWh electricity price, dropping from 110.2 to 55.1 US$/tAl2O3. The capital cost of multi-stage mechanical vapour recompression (MVR) is the dominant component (50%) of the LCOSB in this scenario, while renewable electricity remains the primary operating cost driver. A sensitivity analysis indicates that, with natural gas at 7.5 US$/GJ and no CCSCarbon Capture and Storage (CCS), cost parity is achieved when electricity prices fall below 60 US$/MWh; with CCSCarbon Capture and Storage (CCS), electricity-based steam recoverySteam recovery is cost-competitive for costs above 30 US$/MWh.