Fibrous stock blending control system

Claim 1

A system for controlling the composition of furnish as set forth in claim 1 in which said responsive means also includes means connected to said calculator and to said demand sensing means for providing a signal representative of the actual ratio of the output from said calculator to the output from said demand sensing means.

Claim 3

A system for controlling the composition of furnish in a mixing means for delivery to a paper machine comprising means providing a set point signal representative of a desired ratio of one bone dry stock component to the total of such components required in said furnish, means providing a signal which is a measure of the total demand for fluid stock required in said mixing means, means providing a computed signal which is a measure of the actual rate of flow and also the consistency of fluid stock to said mixing means, said computed signal providing means including a calculator for computing said computed signal from said actual rate of flow and consistency, said fluid stock having said one component contained therein, and means for adjusting the actual rate of flow of said fluid stock to said mixing means in response to said demand and computed signals, whereby the adjustment of the rate of flow of fluid stock controls the amount of said one bone dry stock component in relation to the total of said components required in said furnish.

Claim 5

A system for controlling the composition of furnish in a mixing means for delivery to a paper machine comprising means providing a set point signal representative of a desired ratio of one bone dry stock component to the total of such components, means providing a signal which is a measure of the demand for fluid stocks required at said mixing point, means providing an actual signal which is a measure of the rate of flow and consistency of fluid stock in said mixing means, said fluid stock having said one component contained therein, means deriving a signal representative of the ratio of said actual and demand signals, means comparing said derived ratio signal with said set point ratio signal to produce an error signal which is a measure of any difference therebetween, and means for adjusting the rate of flow of said fluid stock containing therein said one component in accordance with said error signal.

Claim 8

A system for controlling the composition of furnish in a mixing means for delivery to a paper machine comprising a valve for adjusting the rate of flow of fluid stock to said mixing means, said fluid stock containing a required stock component therein, a flow transmitter for providing a signal which is the measure of the rate of fluid stock flow through said valve, a consistency transmitter for providing a signal which is a measure of the consistency of said fluid stock as determined by the amount of said component contained therein, calculator means providing a computed signal indicative of the mass rate of flow of said component as derived from said fluid flow rate and consistency signals, a level transmitter for providing a signal which is a measure of the level of furnish in said mixing means, comparator means for comparing said level signal with a set point signal which is indicative of a desired level of furnish to be maintained at said mixing point, a level controller responsive to any difference between said level set point signal and the level signal provided by said level transmitter for providing a demand signal that is a measure of the amount of furnish needed to maintain a desired level of furnish in said mixing means, means for ratioing said mass rate of flow signal from said calculator means with said demand signal from said level controller to provide an actual ratio signal, means comparing said actual ratio signal with a set point signal representative of a desired ratio of said required stock component to the total of the components required in said furnish, and means responsive to any difference between said actual and desired ratio signals for positioning said valve to adjust the rate of flow of fluid stock to said mixing means in accordance with the value of any such difference.

Claim 13

A system for controlling the composition of furnish in a mixing means for delivery to a paper machine comprising a first valve for adjusting the rate of flow of one fluid stock to said mixing means, said fluid stock containing a required stock component therein, a second valve for adjusting the rate of flow of a second fluid stock to said mixing point, said second fluid stock containing a different required stock component therein, a third valve for adjusting the rate of additive fluid to said mixing point, said additive fluid containing a required additive component therein, a flow transmitter for each valve for providing respective signals each of which is a measure of the rate of fluid stock or additive flow through its particular valve, a consistency transmitter for each valve for providing signals which are measures of the consistency of each fluid flow therethrough as determined by the amount of stock or additive component therein, a calculator for each valve providing signals indicative of the various mass rates of flow of said components and additive as computed from said fluid flow rates and consistency signals, means for summing the signals computed by the calculators associated with said first and second valves to provide a summed signal indicative of the summed mass rate of flow of said stock components, means providing a demand signal which is a measure of the amount of fluid stock needed to maintain the furnish in said mixing means at a desired level, a first means for providing a derived ratio signal representative of the ratio between the first mass rate of flow signal and said demand signal, comparator means for comparing said derived ratio signal with a set point signal representative of a desired ratio of said first stock component to the total of said stock components required in said furnish, and means responsive to any difference between said derived and desired ratio signals for controlling said first valve in accordance with the value of said difference to thereby adjust the rate of flow of said first fluid stock and hence the amount of stock component delivered to said mixing means, second means for providing a derived ratio signal indicative of the ratio between said second mass rate of flow signal and said demand signal, means comparing said second derived ratio signal with a desired set point signal representative of the desired ratio of said second stock component to the total of said components required in the furnish, and means for positioning said second valve in accordance with any difference between said second derived ratio signals, and means for providing a derived ratio signal representative of the ratio between said mass rate of flow signal from said additive mass rate calculator and said summed signal, and means for comparing said derived additive ratio signal with a set point signal representative of the desired amount of additive with respect to the total stock components required in said mixing means, and meaNs for positioning said third valve in accordance with any difference between said derived and desired additive ratio signals.

Claim 14

A system for controlling the composition of furnish in a mixing means for delivery to a paper machine comprising a valve for adjusting the rate of flow of fluid stock to said mixing means, said fluid stock containing a required stock component therein, a flow transmitter for providing a signal which is a measure of the rate of fluid stock flow through said valve, a consistency transmitter for providing a signal which is a measure of the consistency of said fluid stock as determined by the amount of said components contained therein, a calculator having a pair of input lines and an output line, said input lines being connected to said transmitters so that said output line carries thereon a signal indicative of the mass rate of flow of said component computed from said flow and consistency signals, means providing a demand signal which is a measure of the amount of fluid stock needed to maintain the furnish in said mixing means at a desired level, means providing a derived signal which is indicative of the ratio between a difference signal and said demand signal, a comparator for comparing the derived ratio signal with a set point representative of a desired ratio of said stock component to the total components required in said furnish, any difference therebetween constituting said difference signal, a second comparator for comparing the output signal from said calculator with said difference signal, and flow controller responsive to any difference between said output signal from said calculator and said difference signal for positioning said valve in accordance with the value of said difference to thereby vary the rate of flow of fluid stock so as to more precisely introduce into said furnish in said mixing means an amount of stock component in relation to the total components required in said furnish as called for by said set point.