Large eddy simulations of coal gasification in an entrained flow gasifier

• Published in: Fuel (Guildford) Vol. 104; pp. 664 - 680
• Main Authors: Abani, Neerav, Ghoniem, Ahmed F.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.02.2013; Elsevier
• Subjects: Applied sciences; CFD; Coal gasification; Energy; Energy. Thermal use of fuels; Entrained flow gasifier; Exact sciences and technology; Fuels; Large eddy simulations; Multi-phase flow; CFD; Large eddy simulations; Coal gasification; Multi-phase flow; Entrained flow gasifier; Lagrangian model; Mixing; Turbulence; Computational fluid dynamics; Combustion; Devolatilization; Unsteady flow; Modeling; Large eddy simulation; Combustion gas; Reacting flow; Char; Coal; Entrained bed reactor; Performance; Lagrangian method
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2012.06.006

► Multi-phase turbulent flow and coal gasification in an entrained flow gasifier is simulated using LES and RANS. ► LES captures unsteady flow structures in both combustion and gasification zones of the gasifier. ► Unsteady flow structures affect mixing and char-conversion efficiency. ► LES accurately predicts char-conversion efficiency compared to RANS. In this paper, we investigate multi-phase reacting flow in a coal-fed entrained flow gasifier using large-eddy simulations and Reynolds-averaged Navier Stokes models, respectively. An axial-flow type lab-scale gasifier is investigated. The simulations are performed using a Lagrangian–Eulerian method in which the coal particles are modeled using a Lagrangian approach and the gas phase is solved using an Eulerian approach. We compare the performance of LES and RANS results. The coal particle models include devolatilization, char consumption that uses heterogeneous chemistry and two-way coupling of mass, momentum and energy with the surrounding gas phase. The gas phase combustion is modeled using homogenous chemistry and the effect of turbulence on combustion and gasification is modeled using a partially stirred reactor approximation. Results show that LES captures the unsteady flow structures inside the gasifier. We show that modeling the unsteady mixing is critical to the accurate predictions of the gas phase species and carbon conversion in these gasifiers.