CFD Modelling of Reverse Thermal Oxidisers for VAM Abatement - CFD Modelling of Fixed-bed RTO Devices

The project is part of a larger multi‐phase program of study aimed at Computational Fluid Dynamics (CFD) modelling of Ventilation Air Methane (VAM) abatement systems. It has been well established in the literature that VAM abatement can be achieved through a variety of alternative ways but the method to be considered in this study is via two Recuperative Thermal Oxidiser (RTO) devices differing in the solid matrix used for the heat exchange/storage. It must be emphasised here that the purpose of this work is not to model the operation of the RTO devices. Rather, the aim is to determine whether in the event of an explosion within or downstream of the RTO device, the device could contain the pressure wave and reaction front associated with the explosion, in turn, preventing the explosion to reach the mine itself. Therefore, the principal vision here is to numerically assess the detonation and/or flame arrestor properties of RTO devices. In doing so the simulations should create an explosion wave and model its progress as it travels into the RTO to investigate what happens to that pressure wave. As the wave interacts with downstream geometry there is the possibility of quenching due to the presence of (relatively) cold walls but also of acceleration due to turbulence generation and reflection due to the interaction of the wave with walls. The simulations are to investigate these effects for a number of upstream conditions. The relevant research work are conducted in two phases, namely:

• Phase‐I; CFD modelling of chequer‐brick RTO devices;
• Phase‐II; CFD modelling of RTO fixed‐bed devices.

Phase-I covers the results of complementary experimental work specifically carried out for validation of the CFD model. This report consist of three short reports presented in appendices A to C, respectively.

• Computational Fluid Dynamics Analysis of Detonation Tube (Appendix A)
• Experimental Assessment of the Flame Arresting Properties of Chequer-Brick Style RTOs (Appendix B)
• Computational Fluid Dynamics Investigation of Flame Propagation through Chequer Bricks in a Detonation Tube (Appendix C)

Phase‐II consists of the following three parts:

• Generation of the detailed structure of the fixed beds using the discrete element method (DEM) and construction of the non‐structured mesh on the solid particles of the fixed bed;
• Validation of numerical models (both the combustion model developed to generate the explosion wave and the DEM in‐house codes to generate the real fixed beds);
• Comprehensive investigation of the propagation and reflections characteristics of reaction front and pressure waves through the fixed beds of RTOs.