1. 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

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

3. 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

4. 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

5. Refractory and Calcination Models l Multi-layer refractory heat transfer model l Heat transfer and lime calcination CaCO 3 = CaO + CO 2 Heat absorbed 1.679 MJ/kg CaCO 3 @1089K

6. Modeling Output: Gas Velocity

7. Modeling Output: Gas Temperature

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

9. Modeling Output: Flame Shape 0º -5º

10. Modeling Output: Refractory Temperature

11. Modeling Output: Shell Temperature

12. Modeling Output: Kiln Axial Profiles

13. Modeling Output: Gas Flow Animation

14. Modeling Output: Solid Fuel Flow Animation

15. 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

16. 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

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

18. Modeling Application: Oil/Gas Burner Design

19. Modeling Application: Coal Burner Design & NOx Emission

20. Modeling Application: Direct & Indirect Coal Combustion

21. Modeling Application: Burner with Different Primary Air Oil Flame @ Primary Air Ratio of 22% Oil Flame @ Primary Air Ratio of 60%

22. Modeling Application: Burning NCG in Kilns

23. 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

24. 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

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

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

27. Kiln Modeling Inputs: Kiln Geometry - Fire End

28. 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

29. Kiln Modeling Inputs: Kiln Burner Design

30. Kiln Modeling Inputs: Refractory Lining and Property

31. Kiln Modeling Inputs: Kiln Lime Mud

32. Kiln Modeling Inputs: Kiln DCS Data Display

33. Kiln Modeling Inputs: Kiln Operational Data Analyzer

34. Kiln Modeling Inputs: Selected Data Windows - 1

35. Kiln Modeling Inputs: Selected Data Windows - 2

36. Kiln Modeling Inputs: Computed Secondary Air Area

37. Kiln Modeling Inputs: Averaged Mill DCS Data

38. Kiln Modeling Inputs: Operation Conditions - Lime & Fuel

39. Kiln Modeling Inputs: Operation Conditions - Air Supply

40. Kiln Modeling Inputs: Flue Gas Calculation