Methanation Pilot Plant with a Slurry Bubble Column Reactor: Setup and First Experimental Results

As a part of various research projects, a methanation pilot plant with a slurry bubble column reactor (SBCR) was commissioned and operated. The plant has a nominal load of a 100 kW methane output (lower calorific value) with a reactor diameter of 260 mm and a reactor length of 2500 mm. First experimental data on the steady-state and dynamic operation of catalytic CO2 methanation are presented. Steady-state results from laboratory-scale studies (<1 kW methane output) published previously were confirmed qualitatively at the pilot plant eliminating wall effects unavoidable in small-scale reactors. As predicted, high H2/CO2 ratios increase CO2 conversion, but excess H2 apparently promotes decomposition of the liquid phase (dibenzyltoluene) used in the bubble column reactor. Additionally, due to the increased reactor dimensions compared to laboratory equipment, it was now possible to observe a thermal response of the SBCR under conditions of rapid gas load changes characteristic of envisaged power-to-gas applications with volatile renewable electricity. As the predicted robustness of the SBCR-concept toward a dynamic operation with fast load changes was demonstrated successfully, it offers an attractive alternative to the established fixed-bed methanation technologies with their inherent limitations on dynamic operability.