Mass and Energy Balance-Oriented Allocation Mechanism for Petrochemical Product Carbon Footprint

In the refining industry, allocating environmental burdens reasonably among co-products remains a critical challenge for product carbon footprint (PCF) accounting. Focusing on the core atmospheric and vacuum distillation units, this study establishes a refined Material Flow and Energy Flow Analysis (MFA/EFA) framework based on steady-state Aspen Plus simulation. Addressing the limitations of single-criterion methods, a novel hybrid allocation model based on “process energy demand” is proposed and systematically compared with traditional methods across eight scenarios. Sensitivity analysis reveals that PCF results are highly dependent on allocation rules: traditional energy allocation over-penalizes light, high-energy products (naphtha PCF > 0.44 kgCO ₂ e/kg) while underestimating heavy residues (0.375 kgCO ₂ e/kg) due to the neglect of separation energy. Conversely, the proposed Hybrid Calorific Value-Enthalpy Unit (H-LEA-U) method integrates thermodynamic costs, correcting the residue’s PCF to 0.448 kgCO ₂ e/kg to reflect its high sensible heat consumption. The H-LEA-U method is demonstrated to be the optimal paradigm, effectively balancing inherent feedstock energy and processing intensity for precise carbon management.