Energy savings in reheating furnaces through process modelling

Abstract

Nowadays, energy efficiency is a crucial factor for the competitiveness of manufacturing firms, due to the rising of world energy prices and as a consequence of the environmental consciousness concerned with the consumption of non-renewable energy resources. The furnaces for steel reheating are responsible for a large amount of energy consumption, where less than 50% of the energy supplied to the furnace (mainly gaseous fuel) is net energy of steel heating, the remaining is lost. A consistent set of studies, which investigates energy reduction initiatives for the reheating furnaces, can be found in literature. However, almost all the studies are focused on technology alternatives (such as regenerative burners), whereas some others focus their attention on measurement and control action, mainly obtained by IT investments. This study aims at providing a mathematical model for a reheating furnace, by considering the efficiency-temperature relationships of the furnace. The model permits the user to identify the most proper optimization of the temperature-time relations, in the different productive situations, capable of guaranteeing the most energy-efficient reheating operations by preserving logistics performances. In order to make a cost-benefit analysis, different options for the furnace setting and related process operations have been considered with reference to a specific industrial case. The model highlights how improving the operating policies for controlling the key process parameters may lead to energy savings and, consequently, economic benefits, as well as pursuing environmental preservation thanks to the rational use of non-renewable resources.