This paper describes the research activities carried out to assess the performance of an oxygen separation membrane module and the energy and economic benefits achievable through the use of such membranes in steelmaking processes.
Previous studies had highlighted the interest in the steelmaking process following the wide spread of the steel industry and its key role both industrially and economically. In addition, the process is particularly energy intensive, operates at very high temperatures, enables heat recovery, and makes significant use of oxygen. Among the possible sources of energy for heating the membrane module, the process gases exiting the electric arc furnace (EAF) might be used, since they are under high temperature and high flow rate conditions.
The study has been continued this year to identify how to integrate the membrane module into the steel production process, focusing on the typical discontinuity of the process and the need to keep the membrane module at a constant temperature. A basic configuration of the integrated EAF-membrane system has been proposed, including the compressor to compress the air stream to 4 bar, the process air/gas heat exchanger to achieve the desired temperature, the membrane module, and a microturbine to recover energy from the air leaving the module.
Therefore, an analysis based on a real case study has considered the electric furnace at the Ferriere Nord plant. No energy recovery systems are installed at this plant, and the oxygen produced by the membrane module can be fed directly into the electric furnace.
Sizing of integrated system components and estimation of investment and operating costs has been carried out. The cost of oxygen produced with a membrane system is significantly lower than the cost of industrial production – and almost completely negligible compared to the typical purchase cost by an industrial user. In addition, a reduction in the process “carbon footprint” could be achieved in the future by reducing indirect emissions for oxygen production with membrane systems.
The major critical issues identified concern the level of technological maturity (TRL) of membrane separation systems and the need for further efforts and testing to be able to introduce the technology into industrial processes.