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Power-to-Gas approaches comprise different activities to store electric power in form of gaseous energy carriers like hydrogen or methane. The synthesis of SNG (substitute natural gas) and its injection into the natural gas grid allows the utilization of the well-established infrastructure for natural gas storage, distribution and utilization without the need for further changes to the energy system. At the Engler-Bunte-Institut research focuses on catalytic methanation in catalytically coated metallic honeycomb reactors and in slurry bubble column reactors with the aim of evaluating alternative reactor concepts offering optimized heat transfer characteristics as well as maximizing the possibility of dynamic operation. Both concepts are attractive for small to medium scale power-to-gas applications. Hence, a scale-up was performed for bothreactor concepts with the aim of implementation on commercial scale.

Power-to-Gas technologies could play an important role in future energy systems, since they make it possible to store surplus electric energy from fluctuating renewable energy sources such as solar and wind. In Power-to-Gas concepts, the first step towards storage is the production of H2 by electrolysis, a possible further step is methanation. The Engler-Bunte-Institute, Fuel Technology at Karlsruhe Institute of Technology is conducting research on catalytic methanation in slurry bubble column reactors, which represent a highly load flexible reactor technology. To obtain experimental data at a semi-industrial scale a methanation pilot plant was built and commissioned. The plant is equipped with various safety valves, which may release the hazardous gases H2, CO and CH4 in the chemical reactor into the environment in the unintended case of overpressure, which may lead to a flammable and/or toxic cloud, threatening the safety of the workers and other humans near the plant. In this work, the safety evaluation of the accidental release in the methanation plant is performed using the numerical tool GASFLOW-MPI. Both toxicity and flammability of the hazardous gas cloud are analyzed and discussed. A local-global two-step simulation strategy, including a local computational model and a global computational model, is employed to calculate the hazardous gas dispersion efficiently and accurately. In the first step, a local detailed computational model with fine mesh is used to calculate the release mass flow through the exhaust tube and the complicated shock waves directly without any further assumption model such as the notional nozzle model. In the second step, a large-scale model with the relatively coarse mesh is chosen to efficiently predict the hazardous gas dispersion around the entire methanation plant. Moreover, the performances of two different types of exhaust pipes are compared and discussed, and the recommended exhaust pipe design is provided. The simulation results show that version B of the exhaust tubes is more recommendable from the viewpoint of safety.