Evaluation of Waste Heat Recovery Systems for Industrial Decarbonization

Abstract

To maintain or reduce CO<sub>2</sub> emissions with the continually growing world population and related increasing requirements for energy and transportation, decarbonization is a key factor for current and future power systems. One of the sectors where decarbonization is necessary is energy-intensive industries (i.e., steel and iron, cement, aluminum, glass, food and beverage, paper). The industrial sector contributes approximately 28% of global CO<sub>2</sub> emissions. CO<sub>2</sub> emissions from energy-intensive industries can be reduced through several different approaches (i.e., direct: alternative fuel or energy source and Carbon capture systems; indirect: utilization of waste heat). This work focuses on the evaluation of waste heat recovery systems for the steelmaking process. The steelmaking process has three sources of waste heat in three different process steps. The waste heat can be utilized by all potential power generation cycles such as the Organic Rankine cycle (ORC), Steam Rankine cycle (SRC), and supercritical CO<sub>2</sub> (sCO<sub>2</sub> ) cycle as a bottoming cycle. However, due to the large temperature range, potential retrofitting, and limited footprint, a sCO<sub>2</sub> waste heat recovery system could be an ideal candidate for utilizing waste heat streams. This article is focused on the optimization of the potential sCO<sub>2</sub> cycle layouts for a steel plant with several electric arc furnaces (EAF) and with waste heat temperature between 200° to 1300°C. The results show that sCO<sub>2</sub> power cycles can reach cycle efficiencies above 35% with higher net power and primary heat exchanger effectiveness compared to ORC and SRC.