Combustion CFD Modeling
Computational Fluid Dynamics (CFD) flow modeling is a cost-effective engineering tool that can predict major products of combustion. Whether the system is a coal-fired furnace or a natural gas system, ASC's analysis can determine the best design that will improve performance, reducing maintenance costs, and can help achieve regulation compliance.
Using CFD modeling, ASC can predict:
- Gas flow rate
- Temperature
- Moisture
- Radiative heat transfer, and
- Gas composition (including O2, CO, NO, CO2)
Shared goals for both coal-fired and natural gas systems include: reduce NOx and CO, improve heat transfer, and maintaining acceptable O2 levels.
Coal-Fired Furnaces
Additional goals that are unique to coal-fired furnaces include:
- Minimizing loss on ignition (LOI)
- Avoiding component corrosion and erosion
- Decreasing slagging through fly ash tracking
- Reducing unburned carbon, and
- Control reducing atmosphere
Coal flow and primary air balancing can be evaluated and improved with CFD flow analyses.
The particulate trajectory paths from each of the four burners shown on the left indicates the path of representative coal particles as they are consumed due to solid fuel devolatilization and char combustion.
The end of the particle pathline indicates when all coal particle combustibles have been consumed implying effective combustion.
Incomplete char combustion would be indicated as particle trajectories leaving the boiler on the left. This can impact downstream systems such as ESPs, baghouses, and air heater pluggage.
ASC has modeled wall fired boilers (above left) and tangentially fired boilers (above right).
Natural Gas Systems
To diagnose boiler, burner, or furnace issues as fuel imbalances or secondary air imbalances, the combustion system needs to be investigated. CFD flow modeling is frequently used to design and optimize systems, while field testing is appropriate for measuring existing problems.
CFD profiles of velocity, temperature, and O2 inside a boiler are shown in the above images. The results confirm uniform profiles exiting the system.
Furnace High Velocity Thermocouple (HVT) testing is an effective diagnostic tool for quantifying problems near the combustion zone.
Combustion models can include the intricate details of the burner/inlet area (above) for improved assumptions on the incoming flow profiles.
Analyses of flow streamlines (above left) is key while evaluating design iterations. The velocity profiles (above right) indicate non-uniformity throughout the chamber.