SU1227755A1 - System for automatic control of mass and humidity of sheet material - Google Patents

Description

 scanning and with fixed sensors, while the inputs of the units for forming the mass and humidity values with the fixed sensors are associated with the second outputs of the blocks of the mode switch, and

The invention relates to pulp and paper production and can be used to automatically control the mass and moisture content of a sheet material.

The aim of the invention is to increase the speed and accuracy of mass and humidity control.

The drawing shows the functional diagram of the system for automatic control of the mass and humidity of the distal material.

The system contains sensors 1 and 2 of the mass and humidity of the sheet material connected to the corresponding switching units 3 and 4 of the mode. Sensors 1 and 2 are associated with a scanning mechanism across the web 6. The scanning control block 7 is connected to the inputs of blocks 3, 4 and 5 and to the inputs of blocks 8 and 9 of the profile readiness determination and profile processing, respectively. The outputs of the mode switching units 3 and 4 are connected via the transverse profile forming unit 10 to the inputs of the units 11 and 12 of forming the mass values and forming the humidity values during scanning, with the unit 8 connected through the unit 9 with the blocks 13 and 14 of calculating the set mass values and humidity. The inputs of the blocks 13 and 14 are connected to the inputs of the forward blocks 15 and 16, 17 and 18 delays, 19 and 20 corrections, respectively, and their | Inputs are connected to the setpoint control 21 and 22. The blocks 17 and 18 are connected through the first and second blocks 23 and 24 the inputs of blocks 25 and 26 of the subtraction, the second inputs of which are connected with the outputs of blocks 11 and 12 and blocks 27 and 28 of forming the mass and humidity values with fixed sensors 1 and 2,

the outputs of the lead units are connected to the third inputs of the adders, and the output of the second adder is connected to the first input of the pressure regulator, the second input of which is connected to the vapor pressure sensor.

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ABOUT

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and their outputs are connected via regulators 29 and 30 to adders 31 and 32. Blocks 27 and 28 are connected to corresponding blocks 3 and 4 of mode switching. The outputs of the blocks 15, 16, 19 and 20 are connected respectively to the adders 31 and 32. The output of the adder 31 is connected to the actuator 33 of the flow rate of the fibrous suspension, connected through a pump 34 to the pressure chamber 35 of the paper machine, which contains the net 36, the press 37 and a drying part 38 and a calender 39. The output of the adder 32 is connected to the input of the steam pressure regulator 40, the output of which is connected to the actuator 41, and the second input to the sensor 42 of the steam pressure in the cylinders of the drying part 38.

The system works as follows.

The suspension fiber is fed through a mixing pump 34 to a pressure box 35, from where it enters the grid 36 of a paper machine. The cloth 6 passes through the press section 37, the drying cylinders 38 and the calender 39. Sensors T and 2 masses of humidity 7 installed on the scanner are moved across the canvas with the help of electric drive 5. Sensor operation Scanning or Stopping at a point across the width of the canvas is realized by block 7 scan controls. The vapor pressure in the drying cylinders 38 is measured by the sensor 42 and is used to control the steam flow by the controller 40. The flow of fiber suspension is controlled by the actuator 33. The signals from the mass and humidity sensors 1 and 2 are fed to the mode switching 3 and 4.

which are controlled by block 7. In the Stop mode at the point along the width of the web, the signals of mass and humidity from sensors 1 and 2 through blocks 3 and 4 arrive at the corresponding blocks 27 and 28 of forming the values of the mass of humidity at the point. In blocks 27 and 28, digital filtering of the sensor readings is performed according to the formula y (t) ay (t-1) - (- (1-a) -X (t),

where X (t) y (t), .y (t-1)

mass (humidity) sensor readings at time t

the current values of mass (humidity) formed in block 27 (28) at times t, t-1.

At the moment of operation of sensors 1 and 2 in the Scanning mode, signals from them 20 through blocks 3 and 4 enter the profile forming unit 10, in which transverse mass and humidity profiles are formed. Block 10 stores information on the transverse mass profile and 25 humidity, which is updated as each new measurement is received from the sensors. This allows for each step of the control to have information about the entire transverse profile. In blocks 11 zo and 12, the current values of mass and humidity are formed according to the formula

1 N /. I - C

y (t) Gh. ,

35

de y (t)

 x

the current value of mass (humidity) at time t; The array of the transverse mass profile (humidity) accumulated up to the current moment in block 10.

Block 8 works only in scan mode. It determines the sensor coordinate by the width of the web and detects the end point of the scanning cycle. At this moment, it transmits the generated mass and humidity profiles from block 10 to block 9 for processing profiles. In block 9, the smallest in web width and maximum moisture are determined, and the standard deviation of each profile is also calculated. These values are for the calculation of the established mass and moisture values.

15

20 25

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units in blocks 13 and 14, where the calculation is carried out according to the formula

 V v.

- set value by

where is x

-gon

mass (humidity); the minimum (maximum) permissible mass (humidity) taken from the setpoint 21 mass (22 humidity).

The value of D is determined in block 9 depending on the mode of operation of the sensor. In Stop mode at the point of the width of the canvas

 -X ,,

where X. is the mass (moisture) value at the sensor's stopping point taken from the transverse profile;

X - the minimum (maximum) value of mass (moisture) across the width of the canvas.

In the scan mode, where 6 is the root-mean-square otUnTelenie mass (humidity).

The signals from blocks 13 and 14 arrive at the corresponding blocks 15-20. Delay blocks 17 and 18 organize the delay of the set values, i.e. Y, „(t) xj, (t-t),

the output of the delay unit at time t; set value by mass (humidity) at t-L. The delay time t is equal to the transport delay in the object via the appropriate control channel. From blocks 17 and 18, the signal goes to matching blocks 23 and 24, which convert the set values using the formula

Z (t) bZ (t-1) + (1-b) .y (t-1), where Z (t), Z (t-1) are the outputs of the matching unit at the current and previous moments;

(t-1) is the output of the delay unit at the previous moment;

b exp (-Td / T)

where Tn is the interval of control discreteness;

T is the time constant of the object when controlling mass (humidity).

The signals from blocks 23 and 24 arrive at the corresponding blocks 25 and

I r

xj,; (tn

26 subtraction. The difference, which is an error signal, is fed to the controllers 29 and 30, which exert a feedback control effect. Lead units 15 and 16 produce direct action control, which provides accelerated testing of set values. The control action is calculated based on

tJ (t) bTJ (t-1) + i. (t). - cx (t-1),

u (t5,

and (t-1) direct control actions on the current and previous steps;

Where

.t)

t-1)

- set values at current and previous steps;

-coefficient,

b Whr (-T. / T);

-Transmission coefficient of the control object by

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appropriate channel;

; -. Adjustment coefficient, with the initial setting equal to b;

- discretization interval of control;

- constant time of the object when controlling mass (humidity).

Blocks 19 and 20 of the corrected section produce signals that compensate for the mutual influence of the mass and 5 control channels and humidity. The mass control signals from the output of the blocks 15 and 29 start on the adder 31, where they are added with a correction signal for moisture. output from the unit 20. The total control signal is fed to the actuator 33 of the flow rate of the fibrous suspension. The moisture control from the output of the blocks 16 and 30 is applied to the adder 32, where they are added to the mass correction signal from the output of the block 19.- The total control signal is fed to the second input of the vapor pressure regulator 40.

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VNIIPI Order 2270/32 Circulation 355

Sign New

Production polygr, pr-tie, Uzhgorod, st. Project, 4

Sign New

Claims (1)

AUTOMATIC CONTROL SYSTEM FOR MASS AND MOISTURE OF THE SHEET MATERIAL, containing scanning sensors of mass and humidity of the sheet material associated with the scanning mechanism, a scanning control unit, the first output of which is connected to the scanning mechanism, a steam pressure sensor, a steam pressure regulator, the output of which is connected to the actuator, a cross-section forming unit, a mode switching unit, calculation units for the set values of mass and humidity, the first inputs of which are connected to the setters assy and humidity, subtraction blocks, the outputs of which are connected through humidity and mass controllers to the first inputs of the adders, correction blocks, the outputs of which are connected to the second inputs of the adders, the executive mechanism of the flow of fiber suspension associated with the output of the first adder, characterized in that, with the purpose of increasing the speed and accuracy of mass and humidity control, V. blocks of formation of values of mass and humidity during scanning and with stationary sensors, a block for determining the readiness of a profile, a block for processing a profile, a second block for switching a mode, and blocks are entered. control signals, delay units, lead units, and the outputs of the mass and humidity sensors are connected to the first inputs of the corresponding mode switching units, the second inputs of which are connected to the second output of the scanning control unit and the first input of the profile processing unit, while the first outputs of the mode switching units are connected with the corresponding inputs of the block forming the transverse profile, two outputs of which are connected to the inputs of the blocks forming the values of mass and humidity during scanning, and the third the output of the transverse profile forming unit is connected to the first input of the profile 'readiness' determination unit, the second input of which is connected to the third output of the scan control unit, and its outputs are connected to the second input of the profile processing unit, while the outputs of the profile processing unit are connected to the second inputs of the corresponding blocks calculation, the established values of mass and humidity, the outputs of which are connected to the inputs of the blocks delay, correction and anticipation, and output. The delay blocks are connected through matching blocks with the first inputs of the subtraction blocks, the second inputs of which are connected to the outputs of the mass and humidity value generating blocks during scanning and with stationary sensors, while the inputs of the mass and humidity forming blocks with stationary sensors are connected with the second outputs of the blocks a mode switch, the outputs of the lead units connected to the third inputs of the adders, and the output of the second adder connected to the first input of the pressure regulator, the second input of which is connected with steam pressure sensor.