Entrained flow gasification: Surrogate slag property data for model validation

Slag deposition and slag drain restrict the operating and process conditions of entrained flow gasifiers that are operated on ash-containing fuels. Numerical simulations of these gasifiers require mathematical models to describe slag deposition and slag flow. Previous studies, however, have not provided complete and consistent slag property data for the development and validation of slag flow models. Therefore, a preceding study (Fuel 382 A (2025) 132809) carried out pilot-scale entrained flow gasification experiments at the bioliq Entrained Flow Gasifier (bioliq EFG) plant. The membrane-wall reactor of this plant is equipped with a segmental cooling screen, which was recoated before the experiments to ensure well-defined heat transfer conditions. The experiments were conducted with mixtures of ethylene glycol and glass beads as well as pyrolysis oil and glass beads at thermal inputs of up to 5 MW and operating pressures of 40 bar. Ethylene glycol and glass beads were used as surrogates for pyrolysis oil and straw ash, respectively, in order to derive experimental data under well-defined conditions for the development and validation of slag flow models. This study investigated deposited and discharged glass slags from the pilot-scale experiments. Samples of slag deposited on the membrane-wall refractory were analysed for density and morphology, while samples of discharged slag were analysed for chemical composition, melting behaviour, density, surface tension, morphology, dynamic viscosity, thermal conductivity and specific heat capacity. In addition, the thickness of the slag depositions was measured after reactor shut-down. The analyses and measurements provided complete and consistent data for the development of slag layer and slag flow models. The predictions of one-dimensional slag layer simulations showed good to fair agreement with the measured slag thickness data.