Exploring the improvement potentials in an existing industrial olefin plant through advanced exergy-based analyses

Abstract

The production of light olefins via the thermal cracking of hydrocarbons is the most energy-demanding process in the petrochemical industry, and an important producer of greenhouse gasses worldwide. But, which sections or components of this process are major contributors to its energy-intensiveness, and high environmental impacts? And, how these problems can be avoided and to what extent?Presently, conventional and advanced exergetic, exergoeconomic, and exergoenvironmental analyses are introduced as the most promising methods which could answer these questions, therefore, in this work, are used to identify the real priorities of improvement in an olefin plant in the south of Iran (Assaluyeh), by first simulating the plant in ASPEN HYSYS simulator. The environmental impacts of components and input streams of plant were calculated using Eco-Indicator 99 method of Life Cycle Assessment (LCA). Results of the study indicated that although the cracking furnace causes 55.3% of total exergy destruction of the plant, only 15.36% of it is avoidable endogenous. Furthermore, the considerable share of steam system in the total exergy destruction of plant (as the second exergy destructive section with a share of 14%) showed that ignoring this zone of an olefin plant in the exergy-based analyses leads to major mistakes to diagnose the priorities of improvements. The results showed that considering prespecified costs and environmental impacts for internal material or energy streams produced within the process introduces a significant error to identify the improvement priorities regarding the economic and environmental aspects.