1. Numerical simulations of particle deposition on super-heaters
A fundamental study
Oslo,
Nils Erland L. Haugen

2. Introduction Main focus: Particle inertial impaction
No thermophoresis, eddy diffusion or Brownian motions
This work has been done under the NextGenBioWaste project

3. Simulations Direct Numerical Simulations (DNS) are used
No modeling
No filtering
All space and time scales are resolved
Including the thin but important boundary layer around the cylinder
The Pencil-Code
128 CPUs

4. The Stokes number

5. Particle impaction (0.01<St<0.3)
Re=20
Re=420
Re=6600

6. Front side impaction efficiency

7. Front side impaction efficiency
Classical impaction
Boundary stopping
Boundary interception

8. Back side impaction

9. GKS (MSWI in Schweinfurt, Germany)
Super heater fluid specifications:

10. GKS particle impaction
Re=20
Re=420
Re=1685

11. Impaction efficiency as function of particle diameter
Three orders
of magnitude

12. Impaction rate
Particle mass density
pr. bin (independent
of bin size)

13. Conclusion
DNS is required in order to resolve the important boundary layer
Both the front and the back side impaction depends strongly on Reynolds number
The total mass impaction rate at the super-heater of the GKS plant is totally dominated by particles larger than ~30 microns

14. Turbulence

15. Single cylinder vorticity
Re=20
Re=420
Re=6600

16. Particle impaction (0.4<St<40)
Re=20
Re=420
Re=6600

17. Alternative to the Stokes number