Collaborative optimization of pollution and carbon reduction through carbon flow tracking integrated with life cycle assessment for petrochemical production

A precise management framework is the first step towards multi-factor relationship optimization and environmental benefit maximization. However, refinery-chemical integration faces incongruity between increasing production demand and pollution mitigation owing to multi-factor interconnectedness and incomplete impact evaluation. The material and energy characteristics of the petrochemicals were considered to establish an integrated analysis framework using material-energy-coupled carbon flow tracking and life cycle assessment (LCA) of the entire process. Coupled analysis revealed that the refinery and chemical blocks accounted for 84.1 % and 15.9 % of the carbon flow, respectively, with a total carbon transformation of 73,667.1 kt carbon equivalent (C eq). Notably, multi-level carbon emission factors were calculated aligning with the proportion of carbon metabolism as the weight, among which the refinery-chemical integration reached 0.11 t CO2 equivalent (CO2 eq)/t scale. The LCA results indicated that the overall environmental contribution of the refinery block was considerably greater than that of the chemical block (82.82 % vs. 17.18 %), in which the major contributors were crude oil and ethylene, respectively. On this basis, an optimized scheme for waste resource recycling was proposed by converting petroleum coke to synthesis gas, which reduced the damage value by 2,484.0 MPt compared with the original process. This study provided a theoretical foundation for the precise management and practical support for the collaborative optimization of pollution and carbon emission reduction in the petrochemical industry.