advanced process modeling improves efficiency process simulations ltd. 206-2386 east mall,...
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Process Modeling Principle of Conservation Mass Momentum Energy ……. IN = OUTINOUT OUT 3D CFDTRANSCRIPT
Advanced Process ModelingImproves Efficiency
Process Simulations Ltd.206-2386 East Mall, Vancouver, BC, V6T 1Z3
www.psl.bc.ca
Dave Stropky and Jerry Yuan
Contents
Introduction to Process Modeling
Examples Recovery and Power Boilers Lime Kilns Aerated Wastewater Lagoons Precipitators
Process Modeling
Principle of Conservation
MassMomentum
Energy…….
IN = OUT
ININ
OUTOUT
OUTOUT3D CFD
CFD Modeling Examples
Building StructuresJet engines
Weather
Aircraft
Industrial Equipment
Process Modeling
IN IN PROGRESSPROGRESS
INDUSTRIALINDUSTRIALAPPLICATIONAPPLICATION
Literature review
Plant\Mill interaction
Process knowledge
Commitment of industry
Physical model
Numerical model
Model development
Model validation
Industrial testing
Parametric studies
Problem Solving
Model proposed retrofits
Equipment Optimization
Cost Reduction
INITIALINITIALSTAGESTAGE
Pulp and Paper Modeling Applications
RecoveryandBark
Boilers
Analyze the existing air and fuel system Improve gas mixing and combustion effectiveness Lower excess air necessary for complete combustion Minimize particulate carryover and unburned char Minimize emissions of CO2, CO, TSR, and NOx Increase the range of operational conditions Improve overall thermal efficiency Optimize firing strategies for different loads/fuels Increase the capacity of the boiler Improve the stability of the boiler Minimize the danger of bed blackouts Minimize the danger of waterwall tube failure Provide valuable operational information for mill personnel
Boilers
Boilers
Air System Evaluation
B u rn er P o rts
O v e rfire A irD is tr ib u to r P or ts U n d er D is t. P o rts
U n d erg ra te A ir
Va llian t B a rk B o ile r
0.150.10.050.040.030.020.010.0010
O 2massfraction
0.050.040.030.020.010.0050.0010
CH 4massfraction 1600
150014001300120011001000900800700600
Temp.T [oC]
July 24 CaseGas 1,430 lb/hrHog Fuel 157,000 lb/hr
101123
170
105125
160
020406080
100120140160180
Feb 4 Feb 12 July 24
NO
x E
mis
sio
n (lb
/hr) pre dic te d
m easured
Boilers
Emission Control
Boilers
Efficiency Improvements
Parameter Units 2002 2003 Comments/ChangeDry-Solids Load KPPH 59.63 63.92 7.2% increase
TRS PPM 3.7 3.1 16.2% decreaseChemical Reduction Efficiency % 81 90.8 12.1% increase
Carryover physical test Grams/5-minutes 164.7 49.8 69.8% decreaseFiring % Solids % 68.2 67.8Steam Temp Deg-F 727 728
# Chill & Blows # 3 1 66.6% decreaseChill & Blow Downtime HRS 31 12 61.3% decrease
Steam Flow KPPH 229.4 229.8 Low press P/S air closed Natural Gas Flow MSCF/HR 25.11 1.67 93.3% decrease
GL Density % 18.3 18.9 3.2% increaseFurnace outlet Flue Gas Temp Deg-F 1609.9 1438.4 10.6% decrease
Lime Kilns
Reduce fuel consumption. Improve Efficiency Adjust primary/secondary air and fuel ratios and burner
settings to maximize kiln efficiency Identify and eliminate thermal hot spots that lead to
reduced brick liner lifetime Develop strategies for reducing ring formation Identify and fix problems with kiln performance due to
hood shape and secondary air ports location and size Evaluate NCG injection alternatives - optimize injection Evaluate alternative fuels Minimize emissions Optimize heat transfer to mud Improve combustion stability through retrofit and
adjustment of the burner and burner structure
Lime Kilns
Lime KilnsGas Temperature
Brick Temperature
0
50
100
150
200
250
300
0 50 100 150 200 250 300Axial Distance (ft)
T( C
)
ModelShell Scan
Lime Kilns
Distance from Kiln Hood [m]
Tem
pera
ture
ofG
asan
dLi
me
[K]
Volu
me
Frac
tion
ofO
2,C
O2,
H2O
inFl
usG
as[v
ol%
]
Em
issi
onof
NO
inFl
ueG
as[p
pmv]
Mas
sFr
actio
nof
Lim
eC
ompo
nent
s[w
t%]
0 20 40 60 80 100
500
1000
1500
2000
0
5
10
15
20
25
30
35
40
010
020
030
040
050
0
0
10
20
30
40
50
60
70
80
90
100
Feed
End
Fire
End
Tgas
CaCO3
CaO
Tck
NO
CO2
O2
H2O
Predicted Axial Profile Data
Lime KilnsHeat Loss Through Shell 3.0 MW
Natural gas flow rate 0.6291 kg/sNatural gas high heating value 54.45 MJ/kgChemical enthalpy from natural gas 34.26 MW Product temperature 1116.5 KNatural gas composition by wt% Product CaCO3 flowrate 0.213 kg/sCO2 0.37% Product CaO flowrate 4.358 kg/sCH4 97.92% Product Inerts flowrate 0.17 kg/sN2 1.71% Physical enthalpy from product 3.60 MWFuel temperature 310.9 K Energy absorbed by calcination 13.06 MWPhysical enthalpy from natural gas 0.05 MW Total enthalpy from product 16.66 MWTotal enthalpy from natural gas 34.31 MW
Total Energy In 38.43 MWProduct Energy Out + Heat Loss 19.66 MW
CaCO3 flow to kiln 7.995 kg/s Energy taken away by flue gas 18.77 MWInerts flow to kiln 0.166 kg/sMaterial temperature to kiln 616.5 K Flue gas CO2 mass flowrate 5.120 kg/sPhysical enthalpy from feed 2.77 MW Flue gas N2 mass flowrate 9.447 kg/s
Flue gas H2O mass flowrate 1.607 kg/sFlue gas O2 mass flowrate 0.354 kg/s
Air composition by wt% Physical enthalpy from flue gas 18.77 MWO2 22.59% Flue gas energy balance check 0.00 MWN2 75.64% Flue Gas Temperature 1029.2 KH2O 1.77%Discharge grate air flowrate 0.602 kg/sDischarge grate air temperature 522.0 KDischarge grate air physical enthalpy 0.18 MWHood leakage air flowrate 8.465 kg/sHood leakage air temperature 310.9 KHood leakage air physical enthalpy 0.70 MWBurner axial air flowrate 2.651 kg/sBurner axial air temperature 366.5 KBurner axial air physical enthalpy 0.37 MWBurner spin air flowrate 0.468 kg/sBurner spin air temperature 322.0 KBurner spin air physical enthalpy 0.04 MWNCG air flowrate 0.289 kg/sNCG air temperature 400.0 KNCG air physical enthalpy 0.05 MWTotal enthalpy air 1.35 MW
Kiln Efficiency 7.09 GJ / tonne
Product
Fuel
Feed
Air
AeratedWastewater
Lagoons
Aerated Wastewater Lagoons
Improve efficiency of waste treatment (BOD removal) by optimizing number and placement of mechanical aerators.
Reduce power consumption from mechanical aerators by either minimizing the number of aerators required or reducing the power load per aerator.
Reduce nutrient supplementation (added phosphorus and nitrogen)
Reduce dredging frequencyImprove design of lagoon basins
Aerated Wastewater Lagoons
Hydraulic Flowand
Residence Time
Side View
0.000
0.010
0.020
0.030
0.040
0.050
0.060
0.070
0 5 10 15 20 25 30 35 40
T(Days)
E(T)
Aerated Wastewater Lagoons
Predicted RTD Curves
Tpeak / Tmean = 0.74Tmedian / Tmean = 0.91
Aerated Wastewater Lagoons
Predicted Biology
Precipitators
Precipitators
Improve precipitator efficiency by redistributing gas flow
Improve duct designsOptimize porous distribution on
perforate plates and locations of platesOptimize baffle and vane designs
Precipitators
V/Vavg [-]: -0.25 -0.15 -0.05 0.05 0.15 0.25 0.35 0.45 0.55 0.65 0.75 0.85 0.95 1.05 1.15 1.25 1.35 1.45 1.55 1.65 1.75 1.85 1.95
Normalized Axial Velocity on a Vertical SectionNew Design 1 of Outlet Perforated Plate
Precipitators
-10%
0%
10%
20%
30%
40%
50%
60%
70%
80%
Outlet Velocity Profile Factor
% R
educ
tion
in P
artic
ulat
e E
mis
sion
s
Modified InletUnmodified Inlet
Conclusions The performance of many pulp and paper
processes is governed by the fluid dynamics, heat transfer, and chemical reactions in the associated equipment.
Much of this equipment was and still is designed and troubleshot using traditional methods. We know what goes in and comes out, but we normally don’t know clearly and in detail what is going on inside.
Advanced three-dimensional process modeling provides a clearer picture of the process dynamics. This knowledge helps mill engineers and operators improve process efficiency and reduce costs.