numerical simulations of particle deposition on super-heaters
DESCRIPTION
Numerical simulations of particle deposition on super-heaters. A fundamental study Oslo, 2010.02.16 Nils Erland L. Haugen. Introduction. Main focus: Particle inertial impaction No thermophoresis, eddy diffusion or Brownian motions This work has been done under the NextGenBioWaste project. - PowerPoint PPT PresentationTRANSCRIPT
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Numerical simulations of particle deposition on super-
heatersA fundamental study
Oslo, 2010.02.16Nils Erland L. Haugen
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Introduction
• Main focus: Particle inertial impaction– No thermophoresis, eddy diffusion or
Brownian motions
• This work has been done under the NextGenBioWaste project
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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
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The Stokes number
D
udSt
f
p
f
p
9
2
viscosityKinematic :
itymean veloc Fluid :
diameterCylinder :
diameter Particle :
density Fluid :
density Particle :
u
D
d
f
p
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Particle impaction (0.01<St<0.3)Re=20 Re=420 Re=6600
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Front side impaction efficiency
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Front side impaction efficiency
Classical impaction
Boun
dary
sto
ppin
g
Boundary interception
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Back side impaction
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GKS (MSWI in Schweinfurt, Germany)
1685
mm 733
/sm 10
C600
m/s 5
24-
v
ud
d
T
u
Re
.
Super heater fluid specifications:
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GKS particle impactionRe=20 Re=420 Re=1685
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Impaction efficiency as function of particle diameter
Three ordersof magnitude
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Impaction rate
Particle mass densitypr. bin (independent of bin size)
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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
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Turbulence
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Single cylinder vorticityRe=20 Re=420 Re=6600
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Particle impaction (0.4<St<40)Re=20 Re=420 Re=6600
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Alternative to the Stokes number
f
pSt