Transcript ORNL CORROSION IN KRAFT DIGESTERS PROGRAM MODELLING UPDATE Project Review Meeting

ORNL CORROSION IN KRAFT
DIGESTERS PROGRAM
MODELLING UPDATE
Project Review Meeting
International Paper
February, 2002
OUTLINE
 Modeling progress
 Kamloops digester
 Problems fixed
 Solid pressure
 Future work
DIGESTER MODEL
 Finite volume
 Curvilinear grids
 Block structured
 Two-phase: liquor flow, solid
flow, temperature, delignification
 Steady
RECENT PROGRESS
 Re-evaluated inlet boundary conditions
 Reworked wall model
 Identified solid pressure problem
- rechecked formulation and implementation
 Addressed velocity profiles issues
Chips, Water and White Liquor
1.666
Bulk Cooking
Trim
(not used)
To liquor
recirculation
pump
9.601
#1
6.706 Dia
0.508 Dia
ORNL Probes (5)
3.176
0.481
To liquor
recirculation
pump
0.914
0.660
1.524
0.305
1.461
0.622
MCC
Screens
0.622
Q1
13.976
0.518
0.385
7.925 Dia
Transition
Wash
Downcomer
Wash Zone
2.823
P=0.15
4.271
6.786
0.660
1.905
P=0.06
#5
FM
Residual
P=0.16
7.772 Dia
(2 rows of 4 x 0.051 pipes)
Flash
Tank
1.270
P=0.17
1.829
(12 x 0.076 pipes)
MCC
Screens
1.461
0.324 Dia
Wash
Downcomer
Cold Blow
MCC
Downcomer
Wash
Screens
Pressure Control
WL
CB
1.499
0.305
CB
(12 x 0.076 pipes)
1.909
1.524
(17’ 6”)
0.686
0.398
All Dimension in m
(P = Porosity)
Cold Blow
(2 rows of 4 x 0.051 pipes)
WL
CB
FM
1.461
#4
Wash
Screens
Pressure Control
9.449
1.524
P=0.15
P=0.17
MCC
Downcomer
7.315 Dia
0.152
#3
CB
WL
Extraction
Screens
1.461
1.270
Extraction
Screens
Q1
51.879
Extraction
Downcomer
(not used)
FM
FM
4.521
6.858 Dia
0.406 Dia
#2
Chips, Water and Whi te Liquor
(190’ 7“)
BS
Brown Stock
6 OUTFLOW BC
5 INFLOW BC
Chip and Liquor Inputs
U (no cone) m/s
Slip velocity
tf
ts
li
ca
Initial solid fraction Eps1in
Initial Liquid fraction in chip
Flow rate liq
Flow rate solid
Total
Pressure top (Pa)
Kappa top
0.0009205
5.62181
158.9
158.9
0.2504
0.548
Extraction screens
W velocity
tf
ts
li
ca
Flow rate
0.380
0.950
21.042
27.620
48.662
83.116
204.985
0.3625671
164.4
164.4
S
S
83.333
Nodes
53
57
Porosity
0.169
2
0.3602467
157.2
157.2
S
S
82.800
Nodes
89
93
Porosity
0.169
1.3611059
62.8
62.8
S
S
78.210
Nodes
113
114
Porosity
0.029
0.6977821
62.8
62.8
S
S
20.790
Nodes
132
133
Porosity
0.026
0.0076345
S
S
S
S
41.667
Nodes
62
67
Porosity
0.157
0.0076345
S
S
S
S
41.667
Nodes
69
74
Porosity
0.157
0.0045890
S
S
S
S
59.617
Nodes
98
103
Porosity
0.153
MCC screens
3
Wash screens
W velocity
tf
ts
li
ca
Flow rate
Brown Stock Blowdown
4
5
1.768
W velocity
tf
ts
li
ca
Flow rate
W velocity
tf
ts
li
ca
Flow rate
Cold blow (8 nozzles + rake)
W velocity (neg)
tf
ts
li
ca
Flow rate
Nodes
38
43
Porosity
0.155
MCC screens
Pressure control
W velocity (neg)
tf
ts
li
ca
Flow rate
0.0105439
S
S
S
S
53.483
Extraction screens
W velocity
tf
ts
li
ca
Flow rate
Wash Discharge
W velocity
tf
ts
li
ca
Flow rate
Nodes
31
36
Porosity
0.155
1
MCC Discharge
W velocity
tf
ts
li
ca
Flow rate
0.0105439
S
S
S
S
53.483
U velocity
tf
ts
li
ca
Flow rate
g
Nodes
Porosity
Kamloops Digester BC
Boundary Condition
Inlet Liquor
Inlet Chips
MCC discharge
Wash discharge
Pressure control
Nozzle and rake cold blow
Extraction screens (2)
MCC screens (2)
Wash screens
Outlet
o
Direction In/Out M (kg/s) Porosity Temp ( C)
Axial
Axial
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Axial
In
In
In
In
In
In
Out
Out
Out
Out
29
79.4
83.3
82.8
78.2
20.8
107
83.3
59.6
outflow
1
1
0.17
0.17
0.03
0.03
0.16
0.16
0.15
1
158.9
158.9
164.4
157.2
62.8
62.8
outflow
outflow
outflow
outflow
1 kg/s)
2 kg/s)
ion
s
kg/s)
ns
g/s)
(20.1(20.1
kg/s)
Chips
kg/s)
Chips
(20.1 kg/s)
Liquor
Liquor
Liquor Chips
Liquor
(78.2(78.2
kg/s) kg/s)
Liquor
Liquor
(78.2 kg/s)
Axial
Axial
Axial
Velocity
Velocity
Velocity
(m/s)
(m/s)
(m/s)
mm/s
w= -0.002 mm/s
w
w
0.00100.0010
0.00060.0006
0.00010.0001
-0.0003
-0.0003
-0.0008
-0.0008
-0.0012
-0.0012
-0.0017
-0.0017
-0.0021
-0.0021
-0.0026
-0.0026
-0.0030
-0.0030
w
0.0010
0.0006
0.0001
-0.0003
-0.0008
-0.0012
-0.0017
-0.0021
-0.0026
-0.0030
+ VEL
+ VEL
+ VEL
MCCMCC MCC
Discharge
Discharge
Discharge
(83.3(83.3
l/s) l/s)
(83.3 l/s)
WashWash Wash
Discharge
Discharge
Discharge
(82.8(82.8
kg/s)kg/s)
(82.8 kg/s)
ns
/s)
ne
Extraction
Extraction
Extraction
Screens
ScreensScreens
(107.0
kg/s) kg/s)
(107.0
(107.0 kg/s)
MCCMCC MCC
Screens
ScreensScreens
(83.3(83.3
kg/s) kg/s)
(83.3 kg/s)
WashWash Wash
Screens
ScreensScreens
(59.6(59.6
l/s) l/s)
(59.6 l/s)
Pressure
Pressure
Pressure
Control
ControlControl
(78.2(78.2
kg/s)kg/s)
(78.2 kg/s)
Cold Cold
BlowBlow
Cold Blow
8 Nozzles+rake
8 Nozzles+rake
8 Nozzles+rake
(20.8(20.8
kg/s)kg/s)
(20.8 kg/s)
Blowline
Blowline
Blowline
w= -0.002
mm/s
w= -0.002
mm/s mm/s
w= -0.002
Liquor
Temp (C)
Tf
170
159
148
137
126
114
103
92
81
70
MCC
Discharge
(83.3 l/s)
Wash
Discharge
(82.8 kg/s)
Chips (20.1 kg/s)
Liquor (78.2 kg/s)
2 Extraction
Screens
(107.0 kg/s)
MCC
Screens
(83.3 kg/s)
Wash
Screens
(59.6 l/s)
Pressure
Control
(78.2 kg/s)
Cold Blow
8 Nozzles+rake
(20.8 kg/s)
Blowline
VELOCITY PROFILES
Liquor
Axial
Velocity
(mm/s)
 Simulations produced large velocity
profiles
w
0.00
-0.50
-1.00
-1.50
-2.00
-2.50
-3.00
-3.50
-4.00
-4.50
-5.00
 For two-phase, chips should not sense + Vel
wall when a few chips diameters inside
the digester
 Liquid will follow the same profile as
the chips
 Improve wall treatment
 Liquid should move slightly faster at
wall
Li
Ra
Ve
(m
Chips
Axial
Velocity
(mm/s)
ws
-0.02
-0.03
-0.04
-0.05
-0.06
-0.07
-0.08
-0.10
-0.11
-0.12
-0.13
+ Vel
WALL BOUNDARY
 Previous calculations had no
slip boundary
 Replaced with
-
free slip
near free slip
relate to solid pressure and wet
friction at wall
 Looked at getting values for
wet friction from PPC
experiments
 Need confidence in solid
pressure calculation
Liquor
Axial
Velocity
(mm/s)
w
-3.33
-3.35
-3.37
-3.39
-3.41
-3.43
-3.45
-3.46
-3.48
-3.50
-3.52
Chips
Axial
Velocity
(mm/s)
+ Vel
ws
-1.25
-1.44
-1.62
-1.81
-2.00
-2.18
-2.37
-2.56
-2.75
-2.93
-3.12
+ Vel
START OF SIMULATION
 Removed conical area as
single phase region
 Start calculation below chip
level
 Ensure input conditions
corresponds to correlation's
used
 Fixed over specification of
problem
-
impose single pressure at top
SLIP AT INLET
 Reevaluation of inlet boundary conditions
Bone Dry Wood Feed to Digester (as solid wood)
Total Solid volume of wood feed (no air, no water)
Water Entering with Chips
Volume of Wood Feed to Digester
Organics formed in Impregnation Vessel
Organics formed in Impregnation Vessel
Net Liquor Flow into Digester Vessel
Bound Liquor Flow into Digester Vessel
Free Liquor Flow into Digester Vessel
chip phase flow rate
free liquor flow rate
Kamloops Inlet
lig
carb
kappa
Eps1in
Pressure (Harkonen eq)
25.0 solid phase
54.8 liquid phase
205.0 den_c
0.380 den_l
83.1 Atop
27.6199
17.2625
27.6199
69.0499
5.5240
5.5240
71.8273
51.7874
20.0399
79.4074
21.0419
79.4
21.0
1150.0
1050.0
35.1
V_l
0.00092
V_c
0.00518
Slip chips
5.62181
SOLID PRESSURE
 Solid pressure governed by
-
weight difference of chips and liquor
two-phase pressure drop
 Checked density of each component as has
large influence on buoyancy force (gravity
force - buoyancy force)
 In 2D and 3D expect different values under
the Can section as buoyancy force not as
strong
SOLID PRESSURE
 Testing of code and comparison with results in
literature showed Ps to be low
 Buoyancy term implemented in source term
did not have effect
 Previous solid pressure at screen was removed
 Line solver does not respond to high source
term due to buoyancy term
-
related to convergence issue
needs to be solved
 Calculated directly works
Next Step
 Solve solid pressure solution problem
 Check delignification model
 Obtain full set calculation for Kamloops
 Obtain next set of conditions and
perform second simulation
- add 3D variations in BC
 Interface results with ORNL boundary
layer code