تحلیل پیامدهای محیط زیستی صنایع پتروشیمی با استفاده از رویکرد ارزیابی چرخه حیات (مطالعه موردی: واحد آمونیاک پتروشیمی خراسان)

Introduction: Throughout the life of a product, all activities and processes are associated with resource consumption and the release of pollutants and materials into the natural environment and some environmental exchanges. In the meantime, petrochemical industries also usually have pollutants and wastes that are dangerous in terms of their nature and chemical composition and may cause environmental crises. To control all environmental effects of a product, its environmental effects must be considered throughout its life cycle. Life cycle assessment determines the transfer of environmental effects from one environment to another and from one stage of the life cycle to another. The purpose of this research is life cycle assessment and estimate the environmental indicators of the ammonia product of Khorasan Petrochemical Company.
Material and methods: The life cycle assessment (LCA) of the ammonia unit at Khorasan Petrochemical Complex was conducted in four main stages: (1) Goal and scope definition, including determination of system boundaries and the functional unit; (2) Life Cycle Inventory Analysis, involving the collection of data on energy and raw material inputs to the system, transportation and distribution modes, and system outputs, including emissions to water, soil, air, and waste generation; (3) Life Cycle Impact Assessment using the ReCiPe 2016 Endpoint (I) method implemented in SimaPro software (v9.0.0.35); and (4) Interpretation of results, in which the inventory and impact assessment results were analyzed and compared in order to propose improvement strategies and to identify and evaluate the environmental impact categories experiencing the greatest damage, as well as the key contributing factors.
Results and discussion: The results indicated that, at the endpoint level, the most significant adverse impacts of this unit are associated with human health, mainly due to the consumption of methane, steam, emissions from the ammonia unit, and natural gas. At the midpoint level, the highest negative impacts were related, respectively, to particulate matter formation, global warming (human health), acidification, and fossil resource scarcity. Methane showed the greatest contribution to particulate matter formation and global warming. Incomplete combustion of methane can generate particulate matter such as black carbon, as well as other pollutants including NOx and CO, which adversely affect particulate matter formation, global warming, and human health. In the fossil resource scarcity category, the main negative impact was attributed to the consumption of natural gas as feedstock, while in the acidification category, methane and steam were identified as the main contributing factors.
Conclusion: Overall, the results demonstrate that the strong dependence of the ammonia production process on fossil fuels and feedstocks, together with emissions associated with methane and the production process, is the main cause of the environmental impacts observed at both midpoint and endpoint levels. Identifying these impacts and proposing targeted mitigation measures can significantly improve the environmental performance of the ammonia unit and reduce its negative consequences. Accordingly, the implementation of CO₂ capture and reduction technologies in the steam methane reforming unit, reduction of methane leakage through continuous monitoring, and establishment of an energy management system based on real-time monitoring of fuel and steam consumption are among the most important recommended measures. In addition, upgrading pollution control systems, optimizing catalyst performance to improve reaction efficiency, recovering heat from furnace and reformer exhaust gases, and optimizing combustion conditions are considered effective strategies. The use of low-NOx burners can further reduce NOx emissions and the associated impacts related to acidification and particulate matter formation. These measures are also applicable to other petrochemical units operating under similar conditions.