Control system for controlling a pulp washing system using a neural network controller

• US 5,282,131 A
• Filed: 01/21/1992
• Issued: 01/25/1994
• Est. Priority Date: 01/21/1992
• Status: Expired due to Fees

• Current Assignee: Brown and Root Industrial Services, Inc.
• Original Assignee: Brown and Root Industrial Services, Inc.
• Inventors: DeGroot, David L., Rudd, John B.
• Primary Examiner(s): Smith, Jerry
• Assistant Examiner(s): GORDON, PAUL P
• Application Number:
  US07/823,313
• Time in Patent Office: 735 Days
• Field of Search: 364/148, 364/162, 364/164, 364/471, 395/20, 395/21, 395/23, 162/49, 162/60, 162/252, 162/253, 162/258
• US Class Current: 700/44
• CPC Class Codes: D21C 7/12 Devices for regulating or controlling
• CPC Class Codes: D21C 9/06 in filters ; Washing of concentrated pulp, e.g. pulp mats, on filtering surfaces
• CPC Class Codes: Y10S 706/906 Process plant

Abstract

A control system for a countercurrent pulp washing process in which the pulp is formed as a pulp mat on at least one moving filter surface and the mat is supplied with rinse water to replace water in the pulp mat thereby reducing the soda loss in the mat before it is removed from the filter surface. The process is characterized by at least one predictable process variable including dissolved solids retained in the pulp mat. The system comprises a trainable neural network having a plurality of input neurons having input values applied thereto and output neurons for providing output values and means for training the neural network to provide predicted values for the predictable process variables.

Claims

1. A control system for a countercurrent pulp washing process in which the pulp is formed as a pulp mat on at least one moving filter surface and that mat is supplied with rinse water to replace water in the pulp mat thereby reducing dissolved organic and inorganic material in the mat before it is removed from the filter surface characterized by measured and directly controlled process variables including flow rate of fresh rinse waster, measured and uncontrolled process variables, at least one predictable process variable including dissolved solids retained in the pulp mat, said process variables having values that define the state of the pulp washing process, said system comprising:

control means responsive to set point values for establishing the value of the directly controlled process variables including the rate of fresh rinse water at said set point values applied to said control means,

means for implementing a trainable neural network having a plurality of input neurons for having input values applied thereto and output neurons for providing output values,

means for training the neural network to provide predicted values for the predictable process variable including mat consistency, mat bulk density, and soda loss at output neurons, said predicted values corresponding to the input values of the neural network,

means for measuring the values of measured process variables,

means for establishing and continuously updating a computer database to store the values of measured process variables,

computer means for establishing the input values at the input neurons of the neural network based upon the values of process variables stored in the computer database,

means for establishing a set point control factor,

computer means for calculating a control factor from measured and predicted process variables and for comparing the calculated control factor to the set point control factor,

computer means for establishing set point values to be applied to control means,

said control system so constructed and arranged that said computer means for establishing set point values, after the neural network has been trained to predict the value of the predictable process variable, changes the set point value of the rate of fresh rinse water to cause the calculated control factor to approach the set point control factor.

2. The system according to claim 1 wherein the control factor is a factor that relates the mass of rinse water added to the system to the mass of pulp flowing through the system.

3. The system according to claim 1 wherein the control factor is the a factor that relates the degree to which the rinse water displaces water in the pulp mat.