CFD Modeling Services

Contact Information

Global NMI Locations

Nalco.com

 

Nalco Mobotec Global 
1601 W. Diehl Rd. 
Naperville, IL 60563 
USA

E-Mail us at:
nalcomobotec@nalco.com

Documents
more
News

CFD Modeling Process

Build Geometry

  • Building from one node through 3D geometry
  • Furnace frame
  • Burner
  • SH and/or RH pendants

Mesh

  • Gambit software
  • Mesh from edge to face to volume

(Usually 1,000,000-1,500,000 grid cell for P.F. boiler, and 500,000 for CFBs)

Set Up the Model

  • Turbulence
  • Heat transfer
  • Radiation
  • Reaction model
  • Particle injection
  • Materials properties
  • Unsteady-state model

Boundary Conditions

  • Wall boundary
  • All inlet mass flow and flow direction
  • Outlet

Iterations

  • Baseline model: 4-5 weeks
  • Each ROFA model: ~ 1 week

Step by Step: The Nalco Mobotec CFD Modeling Process

Step 1: Visit plant, conduct testing, and collect data and drawings

Gather field data for comparison with CFD results

  • High Velocity Testing (HVT) on the furnace:
    • Measures flue gas and furnace temperature levels by inserting specialized probes through access ports. After completing a thorough traverse of the furnace, data can be plotted to determine the furnace performance, and if and where problems exist with air in-leakage, secondary airflow, or side-to-side fuel in-balance within the furnace
    • Obtains an integrated gas sample from the furnace by means of HVT probes to analyze for O2, CO, or NOx
    • Collects coal/fly ash samples
  • Infra-view temperature through all viewports below and above horizontal nose arch
  • Onsite data collection and detailed system survey
    • Typical drawings include:
      • Side view drawing with detailed dimensions
      • Front view drawing with detailed dimensions
      • Plan view of cross-sectional drawings showing the spacing and numbers of SH/RH pendents
      • Detailed drawings of burners
      • Detailed drawing of Over-fire Air (OFA) nozzle if any
    • PI Data at full load includes the following typical variables:
      • MW gross
      • Coal flow
      • All water/steam side data
      • Furnace O2
      • Damper position for all SA
      • Windbox pressure/Furnace pressure
      • Airheater gas in/out temperature; air in/out temperature
      • FD/ID/PA fan damper position
      • Pyrometer readings for furnace temperature
      • Other relevant PI data

Step 2: Perform baseline modeling

Modelers work as a team, going through several iterations on each furnace and tuning each model to validate the conditions found during the plant visit.

  • Build geometry and set up model using ANSYS FLUENT software
    • Example: A typical CFB (circulating fluidized bed) boiler is divided into a half million computational cells, which is believed adequate for solving complex physical and chemical processes involved in a CFB boiler
  • Tune the model and converge the solution
  • Validate the baseline model against test data

Step 3: Conduct ROFA/Rotamix/FSI Modeling

Once baseline is validated, the Nalco Mobotec ROFA system, if purchased, is customized for the specific application. We typically create 3-5 designs for each boiler and model all designs in the CFD study to determine optimal configuration in terms of limestone and/or emission reductions.

In case of NOx reduction, post-processing is performed for NOx predictions.

Step 4: Report results and release design for engineering

After the modeling is complete, Nalco Mobotec lead modelers summarize the CFD study in a 40-60-page technical report, which includes all findings and recommendations. Along with submitting this report, CFD modelers and a Nalco Mobotec chief engineer present the results and answer customer questions.