From laboratory-scale experiments to industrial-scale CFD simulations of entrained flow coal gasification

In this work advanced gasification models of four Australian coals were calibrated using laboratory-scale experiments with the aim of extrapolating these information for simulating large-scale gasification processes using CFD. In particular, the four studied coals, ranging from semi-anthracite to sub-bituminous, were extensively characterized using high-pressure bench and laboratory scale techniques. Coal devolatilization is modeled using the empirical competing two-step models, whose parameters are calibrated in a pre-processing step by means of the advanced CPD, FG-DVC and FLASHCHAIN (R) pyrolysis models. The results of the advanced pyrolysis models are at first validated against true volatile yield data obtained at high pressures and heating rates from wire-mesh reactor experiments. Char gasification is modeled using a nth-order intrinsic kinetics model. At first, intrinsic char kinetics was measured in kinetic regime from experiments in pressurized thermogravimetric analysis. Then, gasification experiments in a laboratory-scale pressurized entrained flow reactor have been used for estimating the reactivity in pore-diffusion regime, defining the diffusivity inside the particle pores. Finally, the calibration of the same coals have also been tested in a 5 MW pilot-scale gasifier, offering a unique opportunity to apply our model over the continuum of laboratory and pilot scales. The model results again show good agreement with the experimental data of syngas composition and carbon conversion evaluated at the exit of the gasifier. The simulations of the pilot-scale gasifier demonstrates that industrial-scale gasification processes can be accurately predicted using advanced coal conversion models, adequately calibrated through laboratory-scale experiments. (C) 2015 Elsevier Ltd. All rights reserved.