SU1432120A1 - Method of controlling temperature duty in digester in sulfite pulping process - Google Patents

Description

I The invention relates to methods for controlling pulp production processes and can be applied in: cellulose-pulp and paper industry.

The purpose of the invention is to provide stabilization of the temperature regime.

The drawing shows the temperature control system in the digester.

The control system for raising the temperature in the sulphate pulp digester includes the digester 1, heat exchangers 2 and 3 connected through the first inputs of the first relay 6 to the first input of the steam flow controller 7, the output of which through the first input of the second relay 8 is connected to valves 9 and 10 of steam supply, and the second input of which is through the first input of the third relay 11, and the input of the task unit 12 is connected to the outputs of the timer 13, the first 14 and the second 15 by computing devices, the inputs of which are through the output of the fourth relay. 16 are connected to the output of a relay 17, the first input of which, together with the timer input, is connected to the first terminal output, the outputs of the condensate temperature sensors 18 and 19, and the temperature sensors 4 and 5 are each connected to their first 20 and second 21 adders, the outputs of which its first 22 and second 23 units of comparison with given values

5pSP

IT, LT, temperature difference

and through the first inputs of the sixth relay 24 is connected to the second input of the third relay, the input of the analyzer 25 is connected to the differentiation unit 26, the input of which is connected to the input of the correction unit 27. The other five inputs are connected to the first output of the terminal, the analyzer's output, to the setters of Koi A and the coefficients jU4, and the output is connected to the second input of the fifth relay, the third input of which is connected via the seventh relay 28 to preset, dS, .5P

value of the derivative (TG) and

a differentiation unit, the output of the first relay is also connected together with a critical temperature setter

chr

with eighth relay 29, input p

relay, the second output of the terminal through the switch 30, the seven inputs of the circuit of the keys 31 are connected via its output to the valves 32 and 33, the cooking liquor 34 and 35, the third inputs

0

five

0

five

0

the first and sixth relays, with the input of the second relay, and the three inputs of the terminal are connected to the setting devices of the current value of the condensate concentration. 5c; , given and H-factor.

The system works as follows (It follows. I One of the signals from the sensors 4 and 5 of the temperature of the cooking solution through the first relay 6 (type P1R.Z) enters the steam flow regulator 7 (of the RPZ type, 21), which through the second turnip 8 (of P1R.Z) changes steam through the valve 9 or 10 to the heat exchanger 2 or 3. The temperature setting to the controller Tj (t) via the third relay 11 (type P1P.Z) comes from the task unit 12 (type MK-46). The time stamps t ,, ..., t are formed by the timer 13, which turns on the signal H ,,, inputted through the terminal. The selector coefficients / and, and are calculated with tvetstvenno (similar to MK-46) in the first 14 and second 15 calculates the s ate GOVERNMENTAL Device Øystein vah.

The signal of the normalized integral criterion H (L through the fourth 16 (type niP. 3) and fifth 17 relays (type P1P, 1) comes from the terminal and is determined from the known dependence

H, 1c, y),

where s

activity of the cooking solution,% content g / l relative to absolutely dry wood; K is a quality indicator of cellulose, dimensionless; Y is the normalizing factor, Cx

X hours

In order to adjust the steam flow, signals from sensors 4 and 5 and from sensors 18 of the condensate temperature of heat exchanger 2. and 19 of heat exchanger 3 enter the corresponding first 20 and second 21 adders (PF1.1), where their difference ΔT and Т T, is calculated which are compared in the first 22 and second 23 comparison units (type P1P.1) with the nominal values

 TI TJ., T1 L T t "L

ST7 and & t:

if b T

that

signal 1 is formed in them, which closes relay 11 through the sixth relay 24 (type П1Р.З), thereby fixing the previous temperature value that is adjusted in step. - In order to further adjust the mode, the current value signal

S, the concentration of the cooking liquor from the analyzer 25 enters differentiation unit 26 (of the type PF 2.1), where

.dS ,.

derivative is determined tg) signal, which enters correction block 27 (MK-A6 type) and signals of normal HT-factor from the terminal and concentration S are also input. In this block, the corrected signal of H-factor is determined by the following equation:

,

where A is the constant of the equation, determined from the condition of the possible minimum boiler turnover, S. h;

| u, jUa - proportionality coefficients, respectively

 g. g1p ytso

The signal derived from block 26 enters the third comparison block (type P2E.Z), in which the fluctuations are filtered, the concentration value S, dS,; fc "

and at (tg) - (jZ) and the output is dtdt

As a signal 1 is generated, it opens the relay 17 and adjusts

S h

The signal Hg is then used through relays 16 in blocks to calculate new jobs T (t). The adjustment is made to the critical temperature of the cooking solution.

when moving

0

five

At the output of the seventh () barely 29 (type P1R.Z) a signal is generated that closes the fourth relay 16, fixing the previous value of the integral and integral criterion.

According to the results of comparing the current condensate concentration values of each heat exchanger to the terminal. and given B, the minimum difference uS is determined by which a signal n for selecting a heat exchanger is formed, through which the latter is connected through switch 30 by closing the necessary circuits in the circuit of keys 31 with the subsequent procedure of closing and opening valves 32 and 33 on the supply lines of the cooking liquor to the boiler and FOR and 35 to the heat exchanger, as well as switching the first, second and sixth relays,

The industrial implementation of this ACS by raising the temperature in the sulphate pulp digester makes it possible, through optimal adjustments, to reduce the quality variation of the pulp produced by 0.65% and save up to 7% of the required amount of steam per each cooking.

j / jJ / “A

III

TTTPG

H yes I

Claims (1)

METHOD FOR MANAGING THE TEMPERATURE REGIME IN THE MOBILE BOILER IN THE SULPHATE BOILING process, which consists in regulating the flow of heating steam in the heat exchanger depending on the measured and set values of the current temperature of the solution at the inlet to the heat exchanger and the heating steam at its output, characterized in that, with In order to ensure stabilization of the temperature regime, during cooking, measure the concentration of effective alkali and the content of the cooking solution in the co-censate of each of the heat exchangers, determine the forecast value the measured indicator of the quality of cellulose from the measured concentration of alkali efficiency and determine the mismatch of the measured and · set values of the content of the cooking solution in the co-censate of the heat exchangers, while switching the recirculation flows of the cooking solution from the heat exchanger with the smallest amount of the found mismatch of the measured and specified values of the content of the cooking solution in condensate, and the flow rate of the heating steam is adjusted according to the calculated value of the cellulose quality index. SU „1432120