Computational simulation of aerosol behaviour Jouni Pyykönen Lectio Praecursoria 22. 3. 2002.
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Computational simulation of aerosol behaviour Jouni Pyykönen Lectio Praecursoria 22. 3. 2002
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Transcript of Computational simulation of aerosol behaviour Jouni Pyykönen Lectio Praecursoria 22. 3. 2002.
Computational simulation of
aerosol behaviour
Jouni Pyykönen
Lectio Praecursoria
22. 3. 2002
Aerosols - Important in many processes
Many dimensions in aerosol issues
Particle size
Physico-chemicalconditions in the
gas phase
Flow fields &residence times
Particlecomposition
Particleshape
Aerosol formation in a laminar flow reactor
Heatedsection
Cooledsection
Nucleationfront
Vapour diffusion
Heat conduction
Heterogeneouscondensation
Non-isothermallaminar flow
In: Saturated vapourfrom the saturator
Out: Cooled aerosolto characterisation
Coagulation
Simulation results
Saturation ratio
[ - ]
Nucleation rate
[#/Ncm3/s]
Particle concentration
[#/Ncm3]
600
200
0
3E5
2E5
1E5
5E4
4E4
3E4
2E4
1E4
0 0
400
Accuracy of the simulations
1E+1
1E+3
1E+5
1E+7
85 90 95 100 105 110
Saturator temperature [°C]
No
ut
[#/c
m3 ]
Computationally Vs. experiments
Vap Par dt DP Coag NSt CPU time N0.02 3 0.05 1.1 No 2 1h 45 min 1.3125105 #/cm3
0.01 3 0.05 1.1 No 2 1h 46 min 1.3107105 #/cm3
0.05 3 0.05 1.1 No 2 1 h 39 min 1.3169105 #/cm3
0.02 0.1 0.05 1.1 No 2 78 h 17 min 1.3123105 #/cm3
0.02 1 0.05 1.1 No 2 6 h 48 min 1.3124105 #/cm3
0.02 Cell 0.05 1.1 No 2 55 min 1.3151105 #/cm3
0.02 3 0.01 1.1 No 2 5 h 23 min 1.3124105 #/cm3
0.02 3 0.2 1.1 No 2 1 h 32 min 1.3128105 #/cm3
0.02 3 0.05 1.01 No 2 8 h 56 min 1.3153105 #/cm3
0.02 3 0.05 1.2 No 2 1 h 43 min 1.3049105 #/cm3
0.02 3 0.05 1.1 Yes 2 3 h 33 min 1.3122105 #/cm3
0.02 3 0.05 1.1 No 4 5 h 46 min 1.3132105 #/cm3
0.02 3 0.05 1.1 No 1 40 min 1.3158105 #/cm3
0.02 3 0.05 20 bins/d No 2 1h 1 min 1.4264105 #/cm3
- - CFD 10 bins/d No - CPUdays 2.5000106 #/cm3
Deposit Formation
Chloride vapours Alkali aerosol particles &coarse mode particles
Turbulent flow instaggered tube array
Boundarylayer
Condensation onaerosol particles
Condensationon deposit
layer
SulphationThermophoresis
Corrosion
Sintering &removability by
sootblowing
Diffusionin porousdeposits
Heattransfer
SO2 HCl
Problematic deposits in FBCand recovery boilers
Coarse particlesticking
Turbulent flow in panel heat heat exchangers
Stagnation point boundary layer
Saturation ratio Temperature [°C]
Mass conc. [g/Nm3] Mass conc. [g/Nm3]
GMM diameter [µm] Number conc. [108 #/cm3]
0
10
20
30
0.0 0.5 1.0 1.5 2.0
Distance from surface [mm]
400
600
800
1000
S
T
16
17
18
19
20
21
0.0 0.5 1.0 1.5 2.0
Distance from surface [mm]
0.0
0.5
1.0
1.5
Vapour
Total
Particle
0.400
0.405
0.410
0.0 0.5 1.0 1.5 2.0
Distance from surface [mm]
2.7
2.8
2.9
3.0
3.1
3.2
Dp
N
Fume: 20 g/Nm3
NaCl: 1 g/Nm3
Flow: 5 m/s, 900 CC
Surface: 480 CC
Max Saturation:
CFD: 24.0
SPM: 24.3
30
0
21
16
0.41
0.4
1000
400
1.5
0
3.1
2.7
0.0 2.0
Deposition & Sootblowing cycle
Fume: 20 g/Nm3
NaCl: 1 g/Nm3
Flow: 5 m/s, 900 CC
Deposit height [mm]
Dep. rate [g/m2/min]
Temperature [C]
NaCl Dep. rate [g/m2/min]
0
5
10
0 50 100 150
400
500
600
700
800
Deposit height
Temperature
0
5
10
0 50 100 150
Particles
Vapour
0.0
0.4
0.8
1.2
0 50 100 150
Time [min]
Particles
Vapour
Total
150
1500
0
Computational simulation of
aerosol behaviour
Jouni Pyykönen
Lectio Praecursoria
22. 3. 2002
