Energy-Efficient Enhancements on the Ethylene Process by Oxidative Dehydrogenation of Ethane Improve Economic Viability and Help Reduce Carbon Intensity

Abstract

Ethylene is a fundamental feedstock for the petrochemical industry. Globally, most production of ethylene is carried out by steam cracking of oil and gas at high temperatures (500–1100 °C). This is a well-established technology with a high environmental impact, relatively low yield, and a wide range of byproducts. In recent years, oxidative dehydrogenation (ODH) of ethane has been investigated as an alternative to achieve a more sustainable route through lower reaction temperatures (<500 °C) and hence lower energy consumption. This study consists of a comprehensive evaluation of an ODH plant design for ethylene production at a capacity of 500 kt/year. Two key process enhancements were applied using process simulation: heat integration with a refrigeration system and energy recovery through a Rankine cycle. Furthermore, an economic sensitivity analysis was performed to assess the impact on NPV by varying the feedstock cost, product selling price, CAPEX, OPEX, and capacity utilization for a range of plant sizes from 250 to 1000 kt/year. As a result, the design showed its robustness to ethane price variation, up to 134% increase. However, it was sensitive to ethylene price variation, up to 23% decrease. It also showed up to 8% OPEX savings with respect to the base design. The NPV was increased by 33% when applying the enhancements. In the environmental aspect, a 42% reduction in carbon intensity was achieved when compared to steam cracking, and the E-factor was 0.7 kg of waste per kg of product.