Deposition and slagging in an entrained-flow gasifier with focus on heat transfer, reactor design and flow dynamics with SPH

• The slag flow of coal ash is simulated in a gasifier with SPH
• The SPH code is coupled with ANSYS Fluent simulations
• Deposition rates are determined by Fluent and serve as input data for the SPH tool
• Two types of coal-ash show different deposition and flow behavior
• Porous zones are generated during the flow and influence heat transfer

Two different types of coal are evaluated in a generic gasifier. The gas and discrete phase in a gasifying process was computed in ANSYS Fluent to determine particle trajectories and deposition rates at the wall. This information serves as input for the slagging tool developed by the authors to simultaneously compute the processes of deposit built-up and slag flow. The tool utilizes the method SPH (Smoothed Particle Hydrodynamics), and due to the particle nature of this method, each particle representing the slag gets its own physical properties such as viscosity or thermal conductivity. Thus the slag's surface and interfaces between solid and liquid layers can be determined without problems. The tool detects critical parts in the gasifier that show increased slag deposit and determines the thickness, temperature profile, and particle distribution of the slag layer. One Puertollano coal and one Colombian coal are evaluated in terms of their slagging propensities, which show different behavior in deposition build-up and flow dynamics. Areas with a low amount of slag matter inside the deposit produce an insulating effect, which changes the physical properties of the slag layer. Predicting the slagging propensities of different types of coal using data acquired from slag simulations can support the gasifier design process.