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You are here : Home > Training > EFPG Days > 6- Effect of wood species mixtures on Kraft pulping (slides 1-8)
        Last update : July 01, 2003
 
                  Second Session : The yield issue                   
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  Logo EFPG     VI - Effect of wood species mixtures on Kraft pulping (slides 1-8)

Christine Deleuze, Denilson Da Silva Perez, Michaël Lecourt (AFOCEL)
 
 
1 - Presentation scope
 
  • Theory
     
  • Application to pulp
    and paper technology

 

   
2 - Problematic
Evaluate the effect of mixing on pulp yield
  No influence ?
  Positive effect ?
  Negative effect ?
  Scheffé’s method allow to study a property as a function of component proportions only.
 
 
3 - Historic
Scheffé's firt applications in 1960's:
        chemistry, oil industry, cake formulations...
Advantages :
  Low number of tests
Easy-reading representation
Best mix proportions determination
No limits in components number...
   
4 - Number of components studied
Is it possible to study more than 3 species interactions ?
In theory: no limit in component numbers...BUT the number of tests to perform increases rapidly with the number of components !
  Interactions
Components
number
Linear Quadratic Cubic
simple
Cubic
full
1 1      
2 2 3    
3 3 6 7 10
4 4 10 14 20
5 5 15 25 35
6 6 21 41 56
7 7 28 63 84
8 8 36 92 120
9 9 45 129 165
10 10 55 175 220
3 to 4 species leads to double the number of components
 
 
5 - Results
Scheffé's polynomials :
 
 
6 - Possible extensions
Introduce process variables:
        No bias
Point out interactions
       
By introducing relation
Kappa number / yield...
...interactions between species
pointed out.
 
 
7 - Interest for pulp and paper industry ?
Use a cheaper fiber resource:
  -- Nearer from mill
-- Long storage
Decrease process cost
Increase pulp yield or / and paper properties
   
8 - Approach for a 3-component mixture
    pure components
  equal composition points
  3-component mix
  three test points for model  validation
 
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