Method for Controlling a Pulping Process

1 - 6 . (canceled)

7 . A method for controlling a pulp digester process for cooking a column of chips comprising:

(a) measuring the size and shape of said chips fed into said pulp digester to provide measured values therefore;

(b) calculating the sphericity factor and the equivalent diameter of said chips based on said measured values;

(c) determining the bulk density of said chip column from said calculated values of said sphericity factor and said equivalent diameter of said chips; and

(d) using a mathematical model to calculate the porosity of said chip column and the pressure loss of liquid flowing through said chip column in the various stages of said cooking process.

8 . The method according to claim 7 including using a mathematical model to calculate the age factor of said cooking process.

9 . The method according to claim 7 for controlling a continuous pulp digester including a chip meter and a plurality of cooking zones including;

(e) determining the output of said pulp digester based on the size and speed of rotation of said chip meter and the bulk density of said chips;

(f) determining a target kappa number and target values for alkali dosage and H-factors required for said output;

(g) calculating the porosity of said chip column in each of said cooking zones of said pulp digester;

(h) calculating the residence time of said chip column in each of said cooking zones in said pulp digester;

(i) calculating the H-factor in each of said cooking zones;

(j) determining the kappa number in each of said cooking zones;

(k) repeating said steps (g) through (j) as necessary;

(l) calculating the pressure loss of liquid flowing through said chip column in each of said cooking zones;

(m) adjusting the set value for said chip meter based on said determined output;

(n) adjusting the set value for said alkali dosage and temperature in each of said cooking zones based on said calculated H-factor and kappa numbers; and

(o) adjusting the set values for the circulation flow rates in said pulp digester in each of said cooking zones based on said calculated pressure losses.

10 . The method according to claim 7 for controlling a batch digester including:

(e) calculating the amount of said chips fed into said pulp digester based on the bulk density and volume of said pulp digester including a plurality of cooling stages;

(f) determining a target kappa number;

(g) determining target values for alkali dosage and H-factor;

(h) calculating said H-factor in each of said cooking stages;

(i) calculating the kappa number in each of said cooking stages;

(j) calculating the porosity of said chip column in each of said cooking stages;

(k) calculating the pressure loss of a liquid flowing through said chip column in each of said cooking stages;

(l) adjusting the set values for the temperature and residence time based on said H-factor and said kappa number; and

(m) adjusting the set values for liquid circulation flow rates in each of said cooking stages.