Thermo-Economic Analysis of Organic Rankine Cycle (ORC) Integration for Low-Temperature Heat Recovery in the Steel Industry: A Case Study on Electric Arc Furnace

Abstract

Steel production process generates massive amounts of flue gases that are released into the ambient system and has the potential to harm the ecosystem and increase the greenhouse gases emissions, thus raising the negative effects of climate change. In steel plants, the electric arc furnaces are widely used to melt raw steel. The melting mechanism uses a high percentage of energy supplied to the plant, as well as producing various temperature grades and mass flow rate of flue gases that are released into the atmosphere. This research explores the opportunity of harnessing low-grade waste heat temperature exhaust gases formed by the electric arc furnaces through utilizing Organic Rankine cycle. The performance of ORC system is assessed by designing experiment matrices based on selected parameters of the ORC which are the flue gas temperature, flue gas mass flow rate, and the working refrigerant. The primary response of the cycle is interrupted through thermal models executed in Aspen HYSYS. The economical aspects of the system were integrated and used further in decision making process. The results highlighted the significance effects of heat source temperature and mass flow rate on cycle power generation. Also, the flow rates of intermediate and refrigerant fluids were mainly impacted by fluids properties and heat source parameters. Although Water-ORC runs obtained effective thermal and economic performance, ORC system with oil as heating medium and R600a as working fluid in the system achieved the highest output power of 78.99 kW and lowest electricity cost of $/kWh0.0580. By examining the primary parameters effects on ORC cycle and potential trends, the research delivers an efficient systematic design approach of ORC in low-grade temperature application.

Date of Award	13 May 2024
Original language	American English
Supervisor	Andrei Sleptchenko (Supervisor)