Gasification kinetics of a bituminous coal at elevated pressures: Entrained flow experiments and numerical simulations

- Entrained flow gasification experiments with a bituminous coal.
- Focus on the impact of total pressure on conversion.
- Modeling approach based on measured intrinsic reaction rates.
- Taking into account thermal annealing and diffusion limitations.
- Good correlation of the simulation results with experimental data.

Predicting conversion rates of solid fuels in entrained flow gasifiers, operating at increased temperatures and pressures, and better understanding the underlying reaction kinetics are of major interest for all industrial gasification applications. Numerical simulations in combination with experiments in lab- and pilot-scale entrained flow reactors help to understand the occuring reaction processes and can be used for gasifier optimization. The presented model is based on the software Ansys Fluent 16.0 and is validated for a bituminous coal with focus on the impact of total pressure. An nth order effectiveness factor approach with measured intrinsic reaction kinetics is applied in order to take diffusion limitations into account, and a thermal annealing model is included in order to account for the influence of decreased reactivities of the char surface due to deactivation, both being relevant at increased operating temperatures. The required model input parameters are derived from pyrolysis experiments and laboratory analyses. The simulation results are in good agreement with experimental data obtained from a pressurized entrained flow reactor operated at the Technische Universität München. The validation experiments are carried out at an operating temperature of 1200 °C, at total pressures of 0.5 MPa, 1.0 MPa and 2.0 MPa, and with a constant molar O/C ratio of one.