Modeling Lime Kilns in Pulp and Paper Mills Process Simulations Ltd. #206, 2386 East Mall, Vancouver, BC, Canada August 23, 2006

Lime Kiln Issues l Kiln efficiency l Lower fuel costs l Burner characteristics l Refractory life l Dams and rings l Stable operation

Principle of Conservation Mass Momentum Energy ……. IN = OUT INOUT OUT Computational Modeling l Build a real size kiln model l Use computer to solve equations l Simulate processes in kiln

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

Refractory and Calcination Models l Multi-layer refractory heat transfer model l Heat transfer and lime calcination CaCO 3 = CaO + CO 2 Heat absorbed MJ/kg CaCO

Modeling Output: Gas Velocity

Modeling Output: Gas Temperature

Modeling Output: Gas Species Concentrations * Other species include CO, H 2 O, NOx, etc.

Modeling Output: Flame Shape 0º -5º

Modeling Output: Refractory Temperature

Modeling Output: Shell Temperature

Modeling Output: Kiln Axial Profiles

Modeling Output: Gas Flow Animation

Modeling Output: Solid Fuel Flow Animation

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

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

Modeling Application: Burning Different Fuels Heavy Oil Petroleum Coke Natural Gas

Modeling Application: Oil/Gas Burner Design

Modeling Application: Coal Burner Design & NOx Emission

Modeling Application: Direct & Indirect Coal Combustion

Modeling Application: Burner with Different Primary Air Oil Primary Air Ratio of 22% Oil Primary Air Ratio of 60%

Modeling Application: Burning NCG in Kilns

Kiln Modeling Inputs: Overview l Site Survey and Measurements l Mass and Energy Balance Calculation l Kiln Geometry l Refractory Lining l Burner Design l Lime Feed Properties l Air Supplies l DCS Data Analysis

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

Kiln Modeling Inputs: Example of Mass Balance Mass In = Mass Out

Kiln Modeling Inputs: Example of Energy Balance Energy In = Energy Out

Kiln Modeling Inputs: Kiln Geometry - Fire End

Kiln Modeling Inputs: Kiln Geometry - Front View l Hood dimension, kiln diameter and length, tilt angle, kiln rotation l Location and size of any openings l Location and tilt angle of burner

Kiln Modeling Inputs: Kiln Burner Design

Kiln Modeling Inputs: Refractory Lining and Property

Kiln Modeling Inputs: Kiln Lime Mud

Kiln Modeling Inputs: Kiln DCS Data Display

Kiln Modeling Inputs: Kiln Operational Data Analyzer

Kiln Modeling Inputs: Selected Data Windows - 1

Kiln Modeling Inputs: Selected Data Windows - 2

Kiln Modeling Inputs: Computed Secondary Air Area

Kiln Modeling Inputs: Averaged Mill DCS Data

Kiln Modeling Inputs: Operation Conditions - Lime & Fuel

Kiln Modeling Inputs: Operation Conditions - Air Supply

Kiln Modeling Inputs: Flue Gas Calculation