Biomass Combustion CFD Simulation, ANSYS Fluent Training

Description

The present problem simulates the biomass combustion process inside a gasifier chamber by ANSYS Fluent software. We perform this CFD project and investigate it by CFD analysis.

The material used for combustion is biomass, which reacts with the oxidizer. It is a biomass substance made from wheat straw that reacts with oxygen to produce synthetic gas as a healthy fuel, and various gas species are involved as reactants or products.

Fuel containing biomass and air enters the chamber from two separate inlets from the upper area. It creates a mass of materials, including ash and semi-combustible coal, in the lower part of the chamber. Finally, the resulting gas is discharged from the outlet at the bottom of the chamber to the next stage, entering the relevant boiler to create the combustion process.

We design the present 2-ِD model and its mesh using Gambit software. The mesh type is unstructured, and the element number is 1108.

Biomass Methodology

In this project, we use the Species model. Since the inlets of air and the fuel are separated, the fuel and oxidizer do not combine before entering the inner space of the chamber. So, we define the reaction as Non-premixed.

We import a PDF (probability density function) file to define the non-premixed combustion. It’s a mixture consisting of biomass, air, and other gaseous species with a rich flammability limit of the fuel flow equal to 0.1 in Fluent software.

Also, the fuel must enter the chamber as discrete particles. It means that the injection of this substance into the chamber is defined based on the Lagrangian view. Therefore, we use the Discrete Phase Model (DPM).

In addition, we define the Radiation model since there is radiant heat energy from the flames in the combustion process. In the present model, we use the P1 model. It’s because the process is related to combustion, and the thickness of its optical layer is high.

Biomass Conclusion

In conclusion, we obtain two-dimensional contours related to pressure, temperature, velocity, and density. We also obtain species mass fraction, water and vapor mass fraction, and radiation temperature.

The results show that, as expected, combustion is formed and performed with the arrival of fuel particles, and the combustion chamber temperature is raised.

The velocity has its maximum value due to the accumulation of particles in the small inlet surface in the inlet area. The highest temperature occurred in the nozzle opening. The results also show the accumulation of soot in the output area of the geometry.