Modeling Lime Kilns in Pulp and Paper Mills

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Modeling Lime Kilns in Pulp and Paper Mills

• Process Simulations Ltd.
• 206, 2386 East Mall, Vancouver, BC, Canada
• www.psl.bc.ca
• August 23, 2006

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Lime Kiln Issues

• Kiln efficiency
• Lower fuel costs
• Burner characteristics
• Refractory life
• Dams and rings
• Stable operation

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Computational Modeling

• Build a real size kiln model
• Use computer to solve equations
• Simulate processes in kiln

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Mathematical Models for Kiln

• Fully three-dimensional Reynolds-averaged
  transport equations of mass, momentum energy, and
  chemical species
• Block-structure body-fitted coordinates with
  domain segmentation
• Two-equation k-e turbulence model
• Ray tracing model for 3D radiation heat transfer
• Gas combustion model
• Lagrangian solid fuel combustion models

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Refractory and Calcination Models

• Multi-layer refractory heat transfer model
• Heat transfer and lime calcination
• CaCO3 CaO CO2
• Heat absorbed 1.679 MJ/kg CaCO3 _at_1089K

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Modeling Output Gas Velocity
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Modeling Output Gas Temperature
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Modeling Output Gas Species Concentrations

• Other species include CO, H2O, NOx, etc.

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Modeling Output Flame Shape
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Modeling Output Refractory Temperature
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Modeling Output Shell Temperature
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Modeling Output Kiln Axial Profiles
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Modeling Output Gas Flow Animation
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Modeling Output Solid Fuel Flow Animation
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Value and Benefit of Kiln Modeling

• Optimize burner design
• Optimize kiln performance
• Evaluate alternative fuels
• Minimize Emissions
• Identify and eliminate thermal hot spots that
  lead to reduced brick lining lifetime
• Identify and fix problems with kiln performance
• Improve waste gas incineration

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Advantages of Kiln Modeling

• Model provides comprehensive information
  throughout kiln at relatively low cost
• Can evaluate what if scenarios to improve
  operation
• Supplements operator knowledge of lime kiln
  operations
• Assists mill managers in making decisions
  regarding kiln retrofits/replacements
• Assists in optimizing burner and kiln designs

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Modeling Application Burning Different Fuels
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Modeling Application Oil/Gas Burner Design
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Modeling Application Coal Burner Design NOx
Emission
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Modeling Application Direct Indirect Coal
Combustion
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Modeling Application Burner with Different
Primary Air
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Modeling Application Burning NCG in Kilns
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Kiln Modeling Inputs Overview

• Site Survey and Measurements
• Mass and Energy Balance Calculation
• Kiln Geometry
• Refractory Lining
• Burner Design
• Lime Feed Properties
• Air Supplies
• DCS Data Analysis

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Kiln Modeling Inputs Site Survey and
Measurements

• Measured streams
• - air in
• - fuel in
• - flue gas out
• - mud in
• - product out
• Measured parameters
• - flow rate
• - temperature
• - composition

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Kiln Modeling Inputs Example of Mass Balance

• Mass In Mass Out

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Kiln Modeling Inputs Example of Energy Balance

• Energy In Energy Out

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Kiln Modeling Inputs Kiln Geometry - Fire End
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Kiln Modeling Inputs Kiln Geometry - Front View

• Hood dimension, kiln diameter and length, tilt
  angle, kiln rotation
• Location and size of any openings
• Location and tilt angle of burner

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Kiln Modeling Inputs Kiln Burner Design
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Kiln Modeling Inputs Refractory Lining and
Property
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Kiln Modeling Inputs Kiln Lime Mud
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Kiln Modeling Inputs Kiln DCS Data Display
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Kiln Modeling Inputs Kiln Operational Data
Analyzer
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Kiln Modeling Inputs Selected Data Windows - 1
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Kiln Modeling Inputs Selected Data Windows - 2
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Kiln Modeling Inputs Computed Secondary Air
Area
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Kiln Modeling Inputs Averaged Mill DCS Data
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Kiln Modeling Inputs Operation Conditions -
Lime Fuel
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Kiln Modeling Inputs Operation Conditions - Air
Supply
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Kiln Modeling Inputs Flue Gas Calculation