Adaptive constant refiner intensity control

A method and an apparatus are provided for maintaining a constant refining intensity under varying tonnage rate and applied power conditions to a slurry of paper stock being passed through a disk type refiner. The system utilizes a control strategy and several unique control algorithms which combine to provide a result which relates the speed of rotation of the refiner elements to the power consumed by the drive motor. The present invention is based on intensity which is defined as the net refining power applied divided by the number of bar crossings (refining elements) per unit time. The system is an adaptive control system which operates on the basis of real time measurements of the refiner process.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a refiner control and is more specifically 
concerned with an adaptive refiner control which operates with respect to 
real time process measurements and adjustable constants to provide a 
calculated main drive speed that is related to the energy drawn by the 
main drive of a refiner. 
2. Description of the Prior Art 
The basic problem faced by paper mills today with respect to refining is 
maintaining the refining intensity, which is a function of refining plate 
design and net energy applied to paper stock, constant for a given grade 
of paper at a varying rate of production and then, using the same refining 
equipment, producing another grade of paper at a different rate of 
production and a new set of horsepower day per ton and refining intensity 
values. Present techniques provide a constant speed of the main drive 
motors; therefore, for a change in production rates, an adjustment in 
refiner power is undertaken to obtain the required horsepower day per ton, 
but the refiner intensity remains virtually unchanged because the speed is 
unchanged. 
Under the foregoing conditions, paper mill personnel must continue to 
adjust refiner power in an attempt to find the optimum refiner setting for 
the desired results. This setting often results in wasted energy. 
SUMMARY OF THE INVENTION 
It is the object of the invention to provide a refiner intensity control 
which is adaptive to the particular refiner requirements and process. 
The above object is achieved through the provision of an adaptive constant 
refiner intensity control which utilizes a variable speed drive and which 
gives rise to the resolution of a number of problems including: 
1. Determining the speed at which the main drive should rotate in 
relationship to net energy applied to the refiner; 
2. Determining no load horsepower on a real time basis and using such data 
for optimization of the total refiner energy requirements; 
3. Determining the actual net energy being applied to the refiner; and 
4. Determining speed of the adjusting mechanism required which would be 
inversely proportional to the energy level of the main drive, there 
allowing an infinitely-adjustable speed range for control stabilization. 
More specifically, the object is achieved through the resolution of the 
aforementioned problems through the solution of a plurality of unique 
algorithms whose values are derived from real time process measurements 
and adjustable constants which result in a calculated main drive speed 
that is related to the net energy drawn by the main drive. 
The accuracy of the control is therefore dependent on the precise 
determination of no load horsepower. Therefore, a unique linear equation 
is used to determine the no load horsepower. A two-dimensional array which 
represents the "fingerprint" of the process in real time is established, 
this fingerprint taking into consideration the no load power at various 
speeds for a given tonnage rate, plus other mechanical and hydraulic 
losses. 
The accuracy of the result is further improved and made adaptive by solving 
the entire no load horsepower equation using a real time measurement of 
flow and consistency. 
The actual net horsepower days per ton can now be calculated using the 
calculated no load horsepower and an actual power measurement from the 
drive motor. 
The result of the aforementioned series of calculations is employed as 
feedback to indicate the imbalance between set point horsepower day per 
ton and actual horsepower day per ton. A balanced condition is 
accomplished by adjusting the refining elements. 
At the same time that the net energy is being adjusted, the equation for 
required speed is being processed. The required speed is a function of the 
inch cuts per revolution of the bars of a refining plate and is constant 
for each refiner plate configuration, net horsepower which is the result 
of a previously-explained calculation and an intensity factor which is a 
numerical constant representing the physical fibre development desired. 
The result of the just-mentioned calculation is the required speed of the 
drive motor for any varying set of conditions. 
In order to ensure that the calculated results are accurately implemented 
by the final control element, i.e. refiner gearmotor, a variable speed 
adjusting device is employed. The actual gearmotor speed is an inverse 
function of power drawn by the main drive, and an adjustable constant 
which results in slower rotational speed of the adjusting device as the 
applied power increases. This unique feature eliminates a common cause of 
control instability which results when drive motors are operated at or 
near their full load ratings and refiner elements are adjusted at some 
predetermined constant speed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
General 
In general terms, the present invention provides the method for maintaining 
refining intensity constant under varying tonnage rates and applied power 
conditions, to a slurry of paper stock being passed through a disk 
refiner. This is accomplished through the use of a control strategy and 
several unique control algorithms which combine to provide a result which 
relates the speed of rotation of the refiner elements to the power being 
drawn by the main drive. Intensity is defined as the net refining power 
applied divided by the number of bar crossings (refiner elements) per unit 
time (IC/REV). Net refining power is defined as the gross horsepower of 
the main drive minus the no load horsepower. The no load horsepower is a 
summation of power required to rotate the refiner elements against the 
resistance due to forces exerted by the paper slurry between the refiner 
elements plus gland frictions, bearing frictions, windage, and internal 
turbulence plus other minor factors which are not completely defined. The 
present invention provides a technique by which a process setpoint is 
established, refiner power required is calculated, refiner elements are 
adjusted at a variable rate which is dependent on the magnitude of the 
applied power, actual net horsepower is determined using the 
aforementioned unique fingerprint method for the no load determination, 
and a rotational speed of the main drive is calculated to maintain 
refining intensity constant for varying process conditions. 
Referring to FIG. 1A and FIG. 1B, the elements of the adaptive constant 
refiner intensity control will be separately explained. 
Mode Selection 
Generally indicated at 10 is the mode selection element which provides a 
means, through operator-selected methods of control, (i.e. freeness 
control, couch vacuum control, horsepower days per ton control or others) 
to indicate in which mode of operation the control system is to function. 
A menu type format is employed, and once the mode of operation is 
selected, proper scaling and range numbers of transmitters are assigned to 
the setpoint portion of the system by associated software subroutines. 
Process Setpoint 
The process setpoint element 12 represents a means of establishing the 
level of desired refining results. 
When the horsepower day per ton (HPDT) mode of operation is selected, the 
proportional, integral, derivative function is not required and is 
bypassed, thus permitting the required HPDT setpoint to be received 
directly by the programmable refiner controller (PRC) 14. 
Programmable Refiner Controller 
The programmable refiner controller 14 receives as its input, 
representative of a required power setpoint, the output of the process 
setpoint element 12. Depending on the mode of operation selected, as will 
be described below under the subheading Mode Selection, the feedback 
signal will be either calculated net horsepower days per ton or actual net 
horsepower. 
The PRC element 14, based on deviation of the feedback signal from the 
setpoint signal, initiates the corrective action required by the disk 
positioning device, i.e. increases or decreases relative refiner elements 
position, until a balanced condition exists. The rate of speed with which 
the repositioning of the refining elements is accomplished will be 
determined by the calculated gearmotor speed element 16. 
Calculated Gearmotor Speed Element 
The calculated gearmotor speed element 16 receives the actual net 
horsepower signal from the actual net horsepower element 18, and through 
the processing of a unique linear equation, determines the speed at which 
the plate adjusting gear motor is to rotate. The calculated gearmotor 
speed equation inverts the speed of the gearometer such that increase in 
main drive power results in a decrease in rotational speed of the 
gearmotor adjusting mechanism. This actual method is described in a 
separate application, Ser. No. 660,522, filed Oct. 12, 1984, fully 
incorporated herein by this reference. 
Refiner Plate Adjustment Element 
The refiner plate adjustment is accomplished using a standard motor starter 
and reversing contactor combination 18. The direction of rotation and the 
on-time duration is determined by the required refiner power element 20, 
while the speed of the gearmotor is predetermined and self-adjusting 
through the calculated gearmotor speed element 16. 
No Load Horsepower 
The no load horsepower element 22 represents a unique method of developing 
an accurate no load value which is, under most conditions, a variable 
whose value changes with the percent load of the main drive motor. The 
term no load horsepower is defined above under the subheading "General". 
For an accurate determination of net horsepower, this value must be 
accurate over the entire load range of the main drive motor. The 
determination of this value is accomplished by a technique called 
fingerprinting, which places in an array, the total no load values of the 
main drive motor at various incremental speeds. The matrix becomes the 
true indication of no load horsepower for the machine under control and 
takes into account all of the various losses defined andundefined that 
exists for the particular machine. 
The matrix contains two fields which record the speed at a particular 
instant and the corresponding no load power value at the same instant. 
This information, in conjunction with the actual speed measurements of the 
variable speed drive system, and combined with a measurement signal 
proportional to stock consistency and stock flow rate, provide the no load 
horsepower value. The use of a measurement of actual stock consistency and 
stock flow rate are necessary in order to provide a representation of the 
change in consistency or flow rate effect on the actual no load 
horsepower. 
The entire process of determining the no load horsepower is represented by 
the following relationship 
##EQU1## 
K.sub.C is the adjustable horsepower constant to trim change in 
consistency effect on no load horsepower; 
CA is the actual consistency; 
CT is the setpoint or target consistency; 
K.sub.F is the adjustable constant to trim change in flow effect on no load 
horsepower; 
FA is the actual flow; 
FT is the setpoint for target flow; 
A is the matrix value power selected by the value of the actual measured 
variable RPM; and 
RPM is the measured variable of speed. 
TABLE IV 
______________________________________ 
SPEED NO LOAD HORSEPOWER ARRAY 
DATA 
POINT RPM A 
______________________________________ 
1 900.0 180.0 
2 899.5 179.8 
3 899.0 179.4 
4 898.5 179.2 
5 898.0 179.0 
6 897.5 178.8 
7 897.0 178.6 
8 896.5 178.4 
9 896.0 178.2 
10 895.5 177.8 
11 895.0 177.4 
12 894.5 177.2 
13 894.0 176.7 
99 401.0 131.0 
100 400.0 130.0 
______________________________________ 
Actual Net Horsepower 
The actual net horsepower being consumed by the main drive motor is 
determined by the relationship 
##EQU2## 
The actual net horsepower calculated is used as feedback information to the 
gearmotor speed calculation, the intensity calculation, the PRC element 
and the % net horsepower element. 
Net Horsepower 
The % net horsepower element 24 determines the of net horsepower being 
consumed by the main drive motor. Its value is derived from the 
relationship 
##EQU3## 
Actual net horsepower is derived from the foregoing relationship and the 
constant K.sub.3 is an adjustable constant which is representative of 
available net horsepower. 
% Flow 
The % flow element 26 determines the actual flow rate at a given instant in 
time and converts this value into a percentage of maximum flow. Its value 
is derived from the relationship 
##EQU4## 
The actual flow value is derived by utilization of a standard flow (mass) 
measuring device such as a magnetic flow transmitter. 
In the above equation, K.sub.4 is an adjustable constant which is 
representative of the calibrated range of the flow measuring device. 
% Net Horsepower Days Per Ton 
The % net horsepower days per ton element 28 calculates the actual net 
horsepower days per ton being applied by the main drive motor, based on 
the flow rate (T/D) and consistency of the material being processed at any 
given instant in time. The % net horsepower days per ton is derived from 
the following relationship 
##EQU5## 
C is the value of measured consistency; P.sub.1 is (1-P.sub.2)/50; 
P.sub.2 is the minimum consistency/mean consistency; 
% flow is the result of the calculation of the percent flow; and 
0.06 is 1/16.62. 
The use of the above equation contained in the % net horsepower days per 
ton is not specifically claimed as the present invention. This procedure 
has been defined and claimed by Mr. Gary Flohr in his U.S. patent 
application Ser. No. 370,577, filed Apr. 19, 1982, allowed Aug. 28, 1984, 
and fully incorporated herein by this reference. 
Intensity Calculation 
The result of the intensity calculation by the element 30 is a signal which 
represents the speed of rotation of the main drive motor which maintains 
the relationship in equality. The required speed of rotation of the main 
drive motor is determined by the relationship 
##EQU6## 
where: NET HORSEPOWER is the result of the actual net horsepower 
calculation; 
IC/REV is the adjustable constant which is dependent on the configuration 
of the refining element design; and 
##EQU7## 
The intensity factor being an adjustable constant which is representative 
of the result required after material is passed through the disk refiner 
and the refining elements. 
Proportional, Integral, Derivative (PID) 
It is not intended to claim herein, in any manner except in combination 
with the other elements of the invention, the standard PID functioning 
which has been known to those skilled in the art for many years. These 
standard functions are employed within the concept of the present 
invention to improve the overall operation. They are included, with 
definition of each, to more readily allow understanding of the present 
invention and are represented by the element 32. 
The term "proportional" or "gain" is the ratio of the change in output to 
the change in input due to proportional control action. 
The term "integral" is the control action where the rate of change of 
output is proportional to the input. 
The term "derivative" is the ratio of maximum gain resulting from 
proportional plus derivative control action to the gain due to 
proportional action alone. 
The above three control functions are finitely adjustable with certain 
limits and represent a means of process tuning the operating control 
scheme. 
A similar circuit 34 is provided for controlling the main drive speed 
setpoint from the speed calculation of the element 30. 
HARDWARE 
Control Circuits 
The individual control circuits or elements set forth above may be provided 
from a plurality of different circuits; however, it has been determined 
that the calculations can be readily handled by a computer, namely a DEC 
(Digital Equipment Corporation) Mod PDP 11-23E computer. The PDP 11-23E 
system comprises a 1 Meg Disk Drive, A/D (Analog-to-Digital) input cards, 
D/A (Digital-to-Analog) output cards, an RSX operating system, and a 
Pascal (UCSD) version compiler. 
Main Motor Drive Package 36 
The main motor variable frequency drive package selected is a 600 HP 
variable frequency controller supplied by Reliance Electric. 
Gear Motor Drive Package 20 
The gearmotor variable frequency drive package selected was a 5 HP variable 
frequency controller supplied by Emerson Electric Co., Model AS270-OTB. 
Gear Motor Adjustment Panel 18 
The gearmotor adjustment panel is manufactured by and available from Beloit 
Corporation per their drawing D42-400788. 
PRC 14 
The programmable refiner controller is manufactured by and available from 
Beloit Corporation per their drawing D42-400983-Gl. 
Power Signal Transmitter 36 
The power signal transmitter selected is manufactured by Scientific 
Columbus, Mod XL. 
Consistency Transmitter 38 
The consistency transmitter is manufactured by the Dezurik Corporation, Mod 
710BC. 
Flow Transmitter 40 
The flow transmitter 40 is manufactured by the Foxboro Company, Mod 2800. 
Freeness Transmitter 42 
The freeness transmitter selected is the Mod Mark III manufactured by 
Bolton Emerson Company of Lawrence, MA. 
Couch Vacuum Transmitter 44 
The couch vacuum transmitter 44 selected, which senses the vacuum on the 
couch roll 46, is manufactured by the Foxoboro Company of Foxoboro, MA. 
The decision elements 52, 54 and 56 are, of course, portions of the PDP 
11-23E system. 
The other operating elements, of course, are the main drive motor 48 and 
the refiner 50 which includes the refiner gearmotor 52. 
Modes of Operation 
As indicated above, a PDP 11-23E computer was selected to implement the 
adaptive constant refiner intensity control technique. As also set forth 
above, the PDP 11-23E is not the exclusive means of implementation. The 
control technique outlined in detail can be implemented using analog 
techniques or digital techniques with properly selected hardware by those 
of ordinary skill in the art of instrumentation application. 
The operation described below is based on digital implementation and will 
be described in small blocks or initial understanding. The last portion 
will tie all of the various operational blocks together to represent the 
complete operating technique. FIGS. 1 and 1A therefore represent both the 
hardware of the system and a flow chart detailing the operational modes of 
the system. 
Mode Selection, Setpoint, Decision 
The mode selection portion of the control system is implemented using a 
cathode ray tube (CRT) terminal interconnected to the computer, this 
terminal being represented at 10. The software modules present the 
operator with an interactive dialog routine requiring input from the 
keyboard (also a part of the element 10) to establish the mode in which 
the control system is to operate, i.e. HPDT mode, couch vacuum mode, 
freeness control mode, and others. 
The selection mode, the setpoint and the decision portion of the control 
technique is represented in FIG. 1 by the elements 10, 12 and 52. 
Using the interactive data received during an initial control setup, the 
following menu and dialog take place during which proper subroutines are 
selected which determine the correct scaling data and constants required 
for the selected mode of operation. At the same time, the various 
decisions are set based on the same input data. 
______________________________________ 
GRADE INPUT MENU 
______________________________________ 
GRADE DESCRIPTIONS 
2 
3 
4 
Select One? 
CONTROL MODE SELECTION 
1. Select Refiner? 
2. Do you wish to run in HPDT mode Y/N? 
3. Do you wish to run in freeness mode Y/N? 
4. Do you wish to run in couch vacuum mode Y/N? 
5. Do you wish to run in "other" mode Y/N? 
You have selected ------ mode for 
refiner No. ------ 
Is your selection correct? Y/N? 
BEGIN INTERACTIVE DIALOGUE 
1. You have selected (grade) ------ 
Is you selection correct? Y/N 
2. Do you wish to initiate Automatic Control? Y/N 
3. Y = "Automatic Control Initiated" 
Subroutine A 
4. N = Transfer to subroutine for constant 
readjustment Subroutine "B" 
______________________________________ 
No Load Horsepower and Actual Net Horsepower 
The no load horsepower element 22 and the actual net horsepower 18 are 
implemented, along with the decision element 54 using a speed, power data 
array established from real time data acquisition techniques, and the 
continuous solution of the no load horsepower equation set forth above for 
the no load horsepower element 22 and the actual net horsepower element 
18. 
Referring to these elements and to the equations therefore, the speed, 
power data matrix, hereinafter referred to as the fingerprint, establishes 
a no load characteristic curve of no load values for the individual motor 
and refiner involved over the entire speed range of the variable speed 
main drive motor 48. This curve, developed in this manner, takes into 
account all power losses due to various circumstances described under 
GENERAL above and represents the true no load values at various speed 
levels of the drive. 
The following schedule represents a typical pseudo-code for completing the 
fingerprinting operation. This fingerprinting operation need be done only 
once prior to initiating automatic control. The fingerprinting process is 
repeated only if mechanical changes are made, i.e. larger horsepower motor 
or different refiner element configurations. 
PSEUDO CODE 
1. Start Main Drive and Accel Drive to Max. Speed, Start Stock Pump. 
2. Check Inlet Pressure and Consistency are within range. 
3. Decel Drive Increments. 
4. Read Drive Power and Speed at each Increment P.sub.(1) S.sub.(2), etc. 
5. Upon completion transfer control to grade input menu. 
It should become apparent to those skilled in the art that the number of 
data points established in the speed, power data array, impacts greatly on 
the accuracy of the curve developed. A typical fingerprinting data array 
is illustrated in the Description of the No Load Horsepower Element set 
forth below, and will be used throughout the balance of this text to 
illustrate actual operation of the control process. The algorithms 
described in equation form have not in all cases been simplified in order 
to provide a more thorough understanding of the concept. 
The no load horsepower element 22 operates as follows. 
1. The value of the speed input is assigned to the program variable AIN. 
2. Using standard array search techniques, the value in the variable A is 
compared to the motor speed values placed in the array during the 
fingerprinting procedure. 
3. The closest possible match to the value contained in the program 
variable AIN is found, the corresponding value of the power at that point 
is assigned to the program variable AOUT. 
4. The no load horsepower equation is solved and a calculated value is 
assigned to the program variable NLHP. 
The following illustrates, numerically, the procedure described above. 
##EQU8## 
where: CA=Actual Consistency from the consistency transmitter 38; 
CT=Setpoint Consistency; 
FA=Flow Actual from the flow transmitter 40; 
FT=Setpoint Flow; 
K.sub.C =Adjustable constant to represent change in consistency effect on 
the corrected no load value for different types of material being 
processed; 
K.sub.F =Adjustable constant to represent change in flow effect for 
different types of material; and 
AOUT=Array value stored in the array at the location indicated by the match 
of the AIM variable to the array speed (RPM) value. 
______________________________________ 
NLHP - DATA ARRAY 
AIN RPM AOUT 
______________________________________ 
898.5 900 180.0 
899.5 179.8 
899.0 179.4 
898.5 179.2 
898.0 179.0 
897.5 178.8 
897.0 178.6 
896.5 178.4 
896.0 178.2 
895.5 177.8 
895.0 177.4 
894.5 177.2 
894.0 176.7 
______________________________________ 
CALCULATION RESULT 
AIN AOUT CA CT FA FT KC KF NLHP 
______________________________________ 
898.5 
179.2 3.5 3.5 1000 1000 .1 30 179.2 
898.5 
179.2 4.0 3.5 1000 1000 .1 30 181.7 
898.5 
179.2 3.0 3.5 1000 1000 .1 30 176.7 
898.5 
179.2 3.5 3.5 1200 1000 .1 30 182.5 
898.5 
179.2 3.5 3.5 900 1000 .1 30 177.5 
898.5 
179.2 3.2 3.5 1100 1000 .1 30 179.5 
______________________________________ 
K.sub.C = .1 
K.sub.F = 2 
The above calculation results indicate that the equation stated can produce 
a result, which can be described as adaptive in nature, when consistency 
and flow values are active inputs to the equation. It also describes the 
procedure for obtaining accurate no load horsepower values which are an 
integral and important portion of the entire control technique. The two 
constants K.sub.C and K.sub.F are empirical and must be derived from 
actual trials. 
ACTUAL NET HORSEPOWER 
The value of the actual net horsepower is determined from the following 
equation. 
##EQU9## 
where: ANHP=Actual Net Horsepower; 
POWER=Actual Kilowatt value obtained from the watt measuring device (power 
transmitter 36); 
0.746=Conversion Factor derived from established definition used to convert 
KW to HP, 
1 HP=33,000 ft-lb/min, 
1 HP=550 ft-lb/sec., 
1 HP=746 Watts, and 
1 HP=0.746 Kilowatts; and 
NLHP=Result of solution to NLHP above. 
Using the above equation for actual net horsepower, the following 
illustrates, numerically, the use of the calculation results from the no 
load horsepower calculation, assuming the motor horsepower to be 1000 HP. 
______________________________________ 
POWER 
IN KW HORSEPOWER NLHP ANHP 
______________________________________ 
745 KW 998.6 179.2 819.4 
600 KW 804.2 181.7 622.5 
500 KW 670.2 176.7 493.5 
______________________________________ 
The above calculation results indicate that the equation, as stated, 
produces an actual net horsepower days per ton value which is based on a 
killowatt to horsepower conversion, less the result of the no load 
horsepower calculation. 
Percent Net Horsepower, Percent Flow, Percent Net Horsepower Days Per Ton 
The percent net horsepower, percent flow and percent net horsepower days 
per ton are provided for the horsepower days per ton mode by the elements 
24, 26 and 28 of FIG. 1 with the additional inputs from the flow 
transmitter 40 and the consistency transmitter 38 and are implemented, as 
indicated, only when a HPDT mode of operation is selected. The conversion 
of values to percent is not per se unique, but a feature of the invention. 
Percent Net Horsepower Days Per Ton 
The percent net horsepower days per ton element 28 represents a standard 
modification to a procedure disclosed in U.S. Pat. No. 4,184,204, granted 
Jan. 15, 1980 to Gary Flohr, assigned to the same assignee as the present 
invention and fully incorporated herein by this reference. 
The object of this element is to convert incoming process measurement 
signals into a net horsepower days per ton value using a unique method 
disclosed in U.S. Pat. No. 4,184,204. The modification of this procedure 
is the percent conversion of the resultant values which is required for 
operation of the present invention, and the fact that the variable percent 
net horsepower is now presented to this element for resolution of its 
equation in a form derived from the above description of the percent net 
horsepower days per ton utilizing the percent net horsepower, the percent 
flow and the consistency measurements and ratios. 
Percent Net Horsepower 
The percent net horsepower element 24 provides a straight forward 
conversion of a value determined by the elements 22 and 18 to a percent 
value. In the numerical examples set forth below for the percent net 
horsepower equation, the constant K3 is adjustable and is representative 
of available net horsepower. Available net horsepower can be described as 
the maximum rated horsepower of the main drive motor 48 minus its no load 
horsepower and assuming the motor horsepower to be 1000 HP and its no load 
horsepower to be 180 HP, the constant K3 is equal to 820 HP. If an actual 
net horsepower is assumed to be 600 HP, then 
% Net HP=Actual Net Horsepower/K3 
% Net HP=100 (600/820) 
% Net HP=73.1%. 
Percent Flow 
The percent flow element 26 provides a conversion procedure which utilizes 
the flow measurement received from the flow transmitter 40 and an 
adjustable constant K4 to produce a value representative of percent flow. 
The constant K4 represents the calibrated range of the flow measuring 
device. Actual flow is the value of the output of the flow measuring 
device at any specific moment in time. If one assumes a flow measuring 
device calibration range of 1000 GPM and an actual flow measurement of 800 
GPM, then 
% Flow=100 (800/1000) 
% Flow=80%. 
Gearmotor Speed, Variable Speed Drive and Gearmotor Plate Adjustment 
These functions are represented by the elements 16, 20 and 21 in FIG. 1. 
They are also disclosed in my earlier application Ser. No. 660,522, filed 
Oct. 12, 1984 and fully incorporated herein by this reference. These 
techniques have been incorporated in the present control process to 
enhance its overall operation and are provided separately below with 
numerical examples. 
Gearmotor Speed 
This section of the control is based on the continuous solution of a linear 
equation using various methods of performing calculations required with 
the result that represents required gearmotor speed. The heart of this 
technique is the concept of varying the output speed of the gearmotor in 
an opposite relationship to the magnitude of the refiner main drive power 
and the basic linear equation is: 
EQU GMSR=GMSMX-[(ACMMP/AVMMP)/GMSMX]+GMSMN 
where: 
GMSR=Gearmotor Speed Required; 
GMSMX=Maximum Gearmotor Speed (An adjustable constant with represents the 
maximum RPM output of the gearmotor); 
ACMMP=Actual Mainmotor Power (A real time measurement of the power being 
drawn by the main drive of the refiner); 
AVMMP=Available Main Motor Power (An adjustable constant which represents 
the maximum horsepower in killowatts that a refiner drive can deliver); 
GMSMN=Minimum Gearmotor Speed (An adjustable constant contained in a 
variable frequency drive controller). 
TYPICAL EXAMPLE 
Assume Main Drive Horsepower=200 
Max.Availble Power=200 HP.times.0.746=149.2 Kilowatt 
Max.Gearmotor Speed=900 RPM 
Min.Gearmotor Speed=50 RPM 
Range of Gearmotor Speed=900 RPM-50 RPM=850 RPM 
Set Max.Speed At=850 RPM 
Assume No load HP=70 HP.times.0.746=52.2 Killowatt. 
______________________________________ 
Main Motor 
Main Motor 
Power Power Max. GM Min. GM 
Gearmotor 
(Actual) (Avail.) Speed Speed Speed 
______________________________________ 
149.2 KW 149.2 KW 850 RPM 50 RPM 50 RPM 
139.2 KW 149.2 KW 850 RPM 50 RPM 106 RPM 
129.2 KW 149.2 KW 850 RPM 50 RPM 163.8 RPM 
119.2 KW 149.2 KW 850 RPM 50 RPM 220 RPM 
______________________________________ 
The foregoing demonstrates that as the actual measured main motor power 
varies, the output speed of the gearmotor varies in opposition thereto. 
Variable Speed Drive 
The variable speed drive 20 represents a standard variable frequency drive 
controller. There are several manufacturers of this type of drive 
controller. The measure requirements of the variable speed drive 
controller are: 
A. Must be capable of receiving the remote control signal derived from the 
Gearmotor Speed Calculation; and 
B. The variable speed drive controller must be sized to accommodate the 
power requirements of the various horsepower rated gearmotors. 
As pointed out above, the gearmotor variable frequency drive package 
selected was a 5 HP VF controller supplied by Emerson Electric Co., their 
Model AS270-0TB. 
Gearmotor Plate Adjustment 
The gearmotor plate adjustment element 21 represents a group of motor 
starters and reversing contactors that receive their operational 
instructions from the programmable refiner controller 14. 
As pointed out above, the gearmotor plate adjustment panel is manufactured 
by and available from Beloit Corporation per their drawing D42-400788 and 
is typical of gearmotor plate adjustment elements which may be utilized in 
practicing the present invention. 
Programmable Refiner Controller 
As pointed out above, the microprocessor-based programmable refiner 
controller is manufactured by and is available from Beloit Corporation per 
their drawing D42-400983-GL. Briefly, its operations consist of accepting 
an input signal from a remote source, comparing this signal to a 
measurement signal from the controlled device and implementing corrective 
action to a disk position device by means of speed and direction of 
rotation signals. It is also typical of a controller which may be employed 
in practicing te present invention. 
Intensity Calculation 
The drive speed calculation illustrated below represents a unique method 
for determining the required rotational speed of the main drive motor 48 
connected to the disc refiner 50 to maintain a constant refining intensity 
for varying process conditions. 
##STR1## 
Intensity was previously defined in the general description as the net 
refining power applied divided by the number of bar crossings (refining 
elements) per unit 
The speed required is the result of continuous solving of the following 
unique equation. 
##EQU10## 
where: Actual Net Horsepower is the mathematical result derived from the 
solution of the Actual Net Horsepower equation described above; and 
IC/REV is the inch cuts per revolution (the summation of the number of bars 
on a refining element in the rotor position times the number of bars in 
the stator position times the lengthcf the bars in each zone of the 
refining element, the summation being multiplied by the revolutions per 
minute). 
Referring to FIG. 2, the following applies: 
EQU IC/M=2[(B.sub.R1 .times.B.sub.S1 .times.L.sub.l)+(B.sub.R11 
.times.B.sub.S11 .times.L.sub.11)+(B.sub.RN .times.B.sub.SN 
.times.L.sub.N)].times.RMP 
where: 
B.sub.Rl =Number of Bars in Rotor, Zone 1; 
B.sub.Sl =Number of Bars on Stator, Zone 1; 
L.sub.l =length of Bar, Zone 1; and 
RPM=Revolutions per Minute. 
______________________________________ 
CALCULATION EXAMPLE 
ZONE B.sub.S 
.times. 
B.sub.R 
= B.sub.S B.sub.R 
______________________________________ 
I 152 208 31,616 
II 225 208 46,800 
III 222 208 46,176 
IV 204 192 39,168 
V 188 176 33,088 
VI 28 40 1,120 
197,968 
197,968 .times. 2 = 395,936 IC/REV 
______________________________________ 
The intensity factor is an adjustable constant empirical in nature used to 
describe the desired results from the refining process. This factor can be 
described by the relationship 
##EQU11## 
Using the same values for horsepower and RPM which were previously used, 
the following will develop an intensity factor that will be used for the 
remainder of this description. Assuming the motor horsepower of 1000 HP 
and the actual net horsepower of 819.4 HP and a speed of 900 RPM for the 
main drive motor 48, the intensity factor IF is 
IF=819.4/(95936.times.900) 
IF=23.sup.-5. 
As stated above, this factor represents the combination of three variables, 
i.e. RPM IC/M which is refiner element dependent and speed of rotation 
which when combined together produce a desired end product. 
With the establishment of an intensity factor, the drive speed calculation 
is 
##EQU12## 
The calculated speed now becomes the setpoint value to the PID function 
element 34. The calculated output from the PID element 34 is fed to the 
speed setpoint portion of the variable speed drive controller 36. A 
feedback signal is returned to the PID element 34 from the element 36 to 
ensure that the drive speed at the value determined by the output of the 
PID element 34. 
Referring to FIG. 3, the control presented herein is comprised of a 
combination of physical measurement about the process, unique algorithms 
to determine various values, and control hardware to implement results 
needed to provide an adaptive constant intensity control of a disk type 
refining machine. FIG. 3 condenses the overall detailed descriptions of 
the invention into a simplified block (flow chart) version. The function 
of each block has been described previously. As is stated, the object of 
the invention is to provide a control system that will be adaptive in 
nature and maintain a constant refining intensity under varying process 
conditions while using one of several primary modes of control such as 
freeness control, horsepower days per ton control, couch vacuum control, 
and others. 
As illustrated in FIG. 3, the basic steps involved are as follows: 
A. The operator initiates the primary mode of control and establishes a 
setpoint value for the mode selected; 
B. As the process measurement varies from setpoint, the refiner plate 
adjustment control repositions the refining element at a rate of speed 
determined by the plate adjustment speed calculation. The change in 
refining element position causes a change in main drive power. 
C. The change in main drive power is recognized by the no load horsepower 
calculation and actual net horsepower calculation elements. The new no 
load horsepower value is inserted into the actual net horsepower 
calculation. The result is that the calculation becomes the process 
measurement signal and is fed back to the programmable refiner control to 
balance the control system at the setpoint value; 
D. The newly-calculated actual net horsepower value is also fed to the 
speed calculation element for the speed calculation algorithm, and a new 
speed setpoint value is developed; and 
E. The main drive motor variable speed controller is instructed, by way of 
the output of the speed calculation element and the proportional, 
integral, derivitive function to readjust its speed. The new speed value 
is fed back to the speed calculation element and the PID function to 
ensure the equation for constant intensity is in equality. 
Significance 
The significance of the present invention is multifold and involves a 
plurality of means and methods for providing an adaptive control for 
maintaining constant refining intensity under varying tonnage rates and 
applied power conditions to a slurry of paper stock be passed through a 
disk type of refiner. These methods and means are: 
1. Providing a method and means to accurately determine the no load 
horsepower values of the main drive motor as a first step in developing an 
accurate overall control technique for providing a uniform product from 
the disk type refiner; 
2. Providing a means and method for controlling the intensity of the 
refining action, based on varying process measurements and product results 
required, is an additional benefit and feature which contributes to a 
uniform product output; 
3. Providing a means and method for adjusting the main drive power speed of 
rotation based on solutions to unique equations contributes to the ability 
of the control technique to produce a uniform product at a main drive 
power consumption less than normally-associated with fixed speed drive 
motor; and 
4. Any improvement in the controllability of the disk refiner variables, 
i.e. horsepower consumed in relative refining element positions, must 
result in an improved end product with less energy consumption for a given 
set of circumstances. 
Although I have described my invention by reference to a particular 
illustrative embodiment thereof, many changes and modifications of the 
invention may become apparent to those skilled in the art without 
departing from the spirit and scope of the invention. I therefore intend 
to include within the patent warranted hereon all such changes and 
modifications as may reasonably and properly be included within the scope 
of my contribution to the art.