Energy efficiency assessment by process heating assessment and survey tool (PHAST) and feasibility analysis of waste heat recovery in the reheat furnace at a steel company

The steel industry is one of the most energy intensive industries, contributing greenhouse gas (GHG) emissions. This research analyzes the feasibility of waste heat recovery and assesses energy efficiency at a steel company, Gerdau Ameristeel in Selkirk, Manitoba. The process heating assessment and survey tool (PHAST) determined that the overall efficiency in the reheat furnace is 60%. Flue gas losses are the biggest energy losses in the reheat furnace, accounting for 29.5% of the total energy losses during full production. Heat losses from wall, hearth and roof are also significant, being 7,139,170 kJ/h during full production. To reduce energy inefficiencies, it is recommended that billets be preheated to 315 °C in the reheat furnace. This requires 1.48 h to capture waste heat with a preheating section length of 1691.64 cm. The annual energy savings are estimated to be $215,086.12 requiring a 3.03 years payback period. This study was the first to determine the required size of a preheating box and the rate of heat transfer through billets in the preheating section.