An extensive simulation of coal gasification in bubbling fluidized bed: Integration of hydrodynamics into reaction modelling

Abstract

The simulation of the coal gasification process in a bubbling fluidized bed reactor was performed in order to estimate the performance of the gasifier and assess the optimal operating conditions. A Eulerian‐Eulerian computational fluid dynamics (CFD) simulation has been developed to predict the hydrodynamic behaviour of the fluidization regime in the bed. This not only provides insight into the hydrodynamics of the bubbling fluidized bed reactor, but also yields hydrodynamics parameters, such as bubble diameter and velocity, solid volume fraction, velocity of gas and solid particles, which can be subsequently used for reaction modelling of the coal gasification process. The predicted hydrodynamic parameters from the CFD simulation are integrated into the kinetics of gasification chemical reactions taking place in the bubble, cloud, and emulsion phases. Instantaneous devolatilization and drying of the feedstock are also considered in the model. The comparison of the predicted results with experimental measurements showed that most of the predicted molar gas compositions in the produced gas were within 15 % of the experimental data. The model was further used to predict the performance of the gasifier at different operating conditions. The results indicated that the temperature range of 800–850 °C, steam‐to‐coal ratios of 0.5–1.5 kg/kg, and air‐to‐coal ratios of 2.0–2.5 kg/kg are suitable conditions for syngas (hydrogen and carbon monoxide, H2 + CO) production. Depending on the application of the produced syngas, the required H2‐to‐CO ratio can be achieved by controlling the air‐ and steam‐to‐coal ratios.

Three dimensional full-loop CFD simulation of hydrodynamics in a pilot-scale dual fluidized bed system for biomass gasification

“…The effect of biomass/char particle is negligible. This assumption has been adopted in many previous studies [9,11,[43][44][45][46] which focus on the hydrodynamic in fluidized bed systems. In this paper, we also focus on the hydrodynamic behaviors, thus the biomass/char particles and chemical reactions are ignored in our simulations.…”

Simulation of high‐temperature steam‐only gasification of woody biomass with dry‐sorption CO2 capture

“…According to Umeki et al, four main gasification reactions occurred, along with seven reactions representing tar formation and cracking steps. To capture CO 2 , an extra reaction was taken into account: the carbonation reaction of calcined Cadomin limestone, the parameters of which were taken from our previous studies . There were two scenarios.…”

“…To capture CO 2 , an extra reaction was taken into account: the carbonation reaction of calcined Cadomin limestone, the parameters of which were taken from our previous studies. [29,30] There were two scenarios. In the first, the model was validated with experimental data found in the literature.…”

Simulation of Biomass Air Gasification in a Bubbling Fluidized Bed Using Aspen Plus: A Comprehensive Model Including Tar Production

“…Regarding pyrolysis, it consists of a set of tremendously complex reactions. However, several works , assumed pyrolysis as an instantaneous process. In fact, it is almost accomplished at the feed inlet of the gasifier.…”