Contributions to the electrification project of multiple hearth furnaces: evaluation of the economic and environmental impacts of the electrical heating technology on CRM pilot facilities

Abstract

Climate change poses a critical challenge for energy-intensive industries, which rely heavily on fossil fuels for high-temperature processes. This thesis investigates the electrification of multiple hearth furnaces (MHFs) as a pathway to decarbonize industrial thermal operations, focusing on two processes: the regeneration of spent activated carbon (AC) and the calcination of hydromagnesite (HM). The study is based on experimental trials conducted on a batch furnace replicating the operating conditions of a single hearth of the MHF, allowing for a controlled comparison between natural gas and electric heating. Experimental results reveal that AC regeneration under electrical heating achieves comparable product quality with 2.5-3 times lower energy consumption than gas-fired operations, highlighting significant efficiency gains and a substantial reduction in direct carbon dioxide emissions. In contrast, HM calcination exhibits technical limitations under the electric configuration, where incomplete gas sweeping leads to carbon dioxide accumulation and partial decomposition, indicating the need for further process adaptation. Environmental and economic assessments, including direct and indirect emissions and operating expenditures under 2023 Belgian conditions, demonstrate clear advantages for electrification. AC regeneration achieves a 75% reduction in total carbon dioxide emissions and a 50% decrease in operating costs, while HM calcination shows reductions of 60% and 45% respectively, albeit with unsatisfying product quality. Sensitivity analyses across European contexts, considering variations in electricity and natural gas prices, carbon prices, and emission factors indicate that electrification benefits are robust for AC regeneration, whereas HM calcination requires specific low-carbon and cost-competitive conditions compared to NG to ensure net benefits. Looking ahead, structural trends in European energy markets, such as declining electricity prices due to renewable expansion and rising carbon costs, are expected to progressively strengthen the competitiveness of electrified heating technologies. Overall, this thesis confirms that electrifying MHFs can deliver substantial environmental and economic benefits, with process-specific adaptations critical for certain applications, thereby supporting the transition of industrial thermal technologies toward a low-carbon economy.