Thermal Effects of Natural Gas and Syngas Co-Firing System on Heat Treatment Process in the Preheating Furnace

Abstract

Preheating furnaces, which are commonly used in many production sectors (e.g., iron and steel), are simultaneously one of the most energy-intensive devices used in the industry. Partial replacement of natural gas with biomass-derived synthesis gas as a fuel used for heating would be an important step towards limiting industrial CO2 emissions. The time dependent computational fluid dynamics (CFD) model of an exemplary furnace was created to evaluate whether it is possible to obtain 40% of energy from syngas combustion without deterioration of thermal parameters of the treated load. As an outcome, a promising method to organize co-firing in the furnace was indicated. The obtained results show that the co-firing method (up to 40% thermal natural gas replacement with syngas), assuming low air-to-fuel equivalence ratio (λNG = 2.0) and even distribution of power among the furnace corners, lead to satisfactory efficiency of the heat treatment process—the heat transferred to the load exceeds 95% of the heat delivered to the load in the reference case), while carbon dioxide emission is reduced from 285.5 to 171.3 kg CO2/h. This study showed that it is feasible (from the heat transfer point of view) to decrease the environmental impact of the process industries by the use of renewable fuels.

Improved Waste Heat Management and Energy Integration in an Aluminum Annealing Continuous Furnace Using a Machine Learning Approach

“…𝑄 𝐴𝑙,𝑧 + 𝑄 𝐹𝐺,𝑧 + 𝑄 𝑤𝑎𝑙𝑙,𝑧 + 𝑄 𝑙𝑒𝑎𝑘𝑎𝑔𝑒,𝑧 = 𝑄 𝑓𝑢𝑒𝑙,𝑧 + 𝑄 𝑟𝑒𝑐𝑖𝑟𝑐𝑢𝑙𝑎𝑡𝑖𝑜𝑛,𝑧 for z = 1-14 (10) where QAl,z is the amount of energy that is effectively absorbed by the aluminum sheet (kW); QFG,z is the energy leaving the ACL furnace with the flue gas (kW); and Qwall,z and Qleakage,z are the heat dissipation through the furnace walls and the leakage losses (e.g., hot gas leakage), respectively. Qfuel,z and Qrecirculation,z are, respectively, the energy input with the fuel consumed and with the heat recovered from recycled flue gases produced at a downstream (hotter) zone (e.g., for heat integration).…”

“…Therefore, it is necessary to develop an accurate operational model for predicting and improving the furnace performance and energy consumption. Computational fluid dynamics (CFD) has been widely applied as a powerful tool for analyzing the heat transfer and fluid flow in heat treatment furnaces [7][8][9][10][11][12]. A three-dimensional CFD model simulates the heat and mass transfer through the specified domain by numerically solving the governing equations in discrete zones called finite volumes.…”

Emerging Tools for Energy System Design Increasing Economic and Environmental Sustainability

“…The first paper on this subject, entitled "Thermal Effects of Natural Gas and Syngas Co-Firing System on Heat Treatment Process in the Preheating Furnace" and authored by Jóźwiak et al [83], examined the possibilities of partially replacing natural gas with synthesis gas derived from biomass. The system under study was a preheating furnace in the steel industry, for which the authors investigated how the air volume, the distribution of burner power, and the share of bio-based gas influenced heat transfer, temperature, and gas flow in the furnace.…”