Delay of biomass pyrolysis by gas–particle interaction

• Simulate interaction between gas and particles and predict both pyrolysis and particle dispersion.
• For volume fractions >10−5 the two-way coupling effects lead to a delay of the biomass pyrolysis.
• For a given volume fraction, the delay decreases with increasing particle size.

We apply a biomass pyrolysis model, based on the model developed by Haseli et al. [4], which can be used in combination with Direct Numerical Simulation. The pyrolysis model is combined with a model for particle tracking to simulate 3D turbulent particle-laden channel flow with biomass particles undergoing pyrolysis in nitrogen. Transfer of momentum, heat and mass between gas and particles are fully taken into account. The effects of this transfer are analyzed and quantified in terms of the delay in the conversion or pyrolysis time. The delay is shown to depend on the initial volume fraction (number of particles) and on the size of the particles. The two-way coupling effects are relevant at volume fractions >10−5. For a fixed volume fraction, gas–particle interaction induces a delay in the devolatilization, decreasing with increasing particle size. Using this model, we also performed simulations of realistic biomass particle size distributions in order to compare two-way and one-way coupling.