Application-based catalytic methanation of steelworks gases under dynamic operating conditions

This paper presents a real and application-based scenario for a dynamically driven catalytic methanation unit, using off-gases from an integrated steel mill as input. Several parameters are subject to dynamic changes during the standard production of steel, such as the available amount and composition of the accumulating process gases, the temperature and operating pressure as well as their periodicity. In addition, the available amount of hydrogen can vary depending on the available fluctuating renewable energy for the installed electrolyzer. Analysis of operating parameters and process routes in steelmaking revealed that among many theoretically possible modes of driving a dynamic methanation unit, which are defined in the literature, there is only one realistic application-based scenario. The definition of this case is supported by experiments performed with a three-stage methanation setup in lab-scale. This experimental campaign covered real cases with dynamic flow rates, adjusting the amount of blast furnace and converter gases based on high variations in the availability of hydrogen. It was possible to achieve very stable product gas compositions, even though load changes in gas input power up to 64% in the range of one to 120 min were executed. The dynamic variations did not result in any additional catalyst deactivation through the whole experimental campaign.