SU1068811A1 - Method of automatic controlling of fibrous suspension cleaning process - Google Patents

Abstract

THE AUTOMATIC CONTROL METHOD FOR THE CLEANING PROCESS OF FIBER SUSPENSIONS in centrifugal cleaners by stabilizing the flow of the suspension supplied to the cleaners, characterized in that, in order to improve the quality of the cleaning of the fiber suspension, determine the mismatch between the measured and nosperfuy and the heart and the heart to change the flow of the flow of the fiber suspension, determine the odds between the measured and the ni? the measured and specified values of weediness after cleaning and depending on the obtained mismatch values change the concentration of the suspension entering the cleaning, after that, the flow rate of the suspension supplied to the cleaners is adjusted, then the number of working g cleaners is changed in accordance with the flow rate of the suspension. (L O5 00 00

Description

The discussion relates to the pulp and paper industry and relates to the method of automatically controlling the cleaning process in centrifugal cleaners. There is a known method for automatically controlling the process of cleaning fiber suspensions in centrifugal tank eyes by stabilizing the flow rate of the suspension supplied to the cleaners 1. A disadvantage of the known method is the low quality of the cleaning of the fiber suspensions. The aim of the invention is to improve the quality of purification of fiber suspensions, which improves the quality of the target product. The goal is achieved by the fact that according to the method of automatic control of the process of purification of fibrous (b suspensions in centrifugal cleaners by stabilizing the flow rate of the suspension supplied to the cleaners, determined the mismatch between the measured and nominal values before cleaning the suspension and between the measured and the specified dust content after depending on the obtained misalignment values, change the concentration of the suspension entering the purification, after which the flow rate of the suspension supplied and the cleaners then change the number of working cleaners in accordance with the value of the flow of the suspension .. The drawing shows a block diagram of a system implementing the proposed method. The automatic control system for the cleaning process of fiber suspensions includes a supply pipeline 1, a 2-circulation water pipeline , dilution tank 3, pipe 4, battery of cleaners 5, pool of cleaning department b, pipe 7, meter 8 before the battery cleaners, meter E after the battery of cleaners, unit 10 disagree Before the battery of cleaners, the error block 11 after the battery of cleaners, the functional block 12 for estimating the influence of input dirt, the functional block 13 for evaluating the influence of immeasurable disturbances, the functional block 14. for calculating the concentration, the regulator 15 for concentration, the sensor 16 for mass concentration, the functional block 17 calculating the mass flow rate, the mass flow controller 18, the mass flow meter 1U, the function block 20 for calculating the number of cleaners, the cleaner 21 switch on controller 21. The system works as follows: the pipeline 1 and the circulating water through the pipeline 2 enter the dilution tank 3, then the diluted mass through the pipeline 4 is fed to the battery of cleaners 5, from where it passes through the pools of the cleaning department 6 to the grinding-preparatory department and paper-making machine. The cleaning mass control system consists of three parts: a concentration control loop, a mass flow control loop, and a cleaner amount control loop. The mass concentration control circuit includes a mass weights meter 8 to a battery of cleaners and a mass weights meter 9 after a battery of cleaners, the outputs of which through a block 10 of the mismatch of nominal weights and weights of mass before the battery of cleaners 11 mismatch of a given weights and weights of the mass after the battery of cleaners are connected respectively to the functional inputs unit 12 for assessing the effect of input filtering on mass cleaning in the battery of cleaners and functional unit 13 for assessing the effect of unmeasuring ah the cleaning process, the outputs of the latter are connected to the inputs to the functional unit 14 for calculating the mass concentration, the output of which, in turn, is connected to the first input of the mass concentration controller 15, and the second input of the latter is connected to the output of the mass concentration sensor 16 coming through the pipeline 4, the output of the regulator 15 affects the flow rate in the return water line 2. The error block 10 of the nominal weights and weights of the mass in front of the battery of cleaners determines the deviation of the actual weights of the mass supplied to the cleaners from the nominal signal received from the meter 8 of the weights of the mass supplied through line 1 by comparing with the given nominal value of weights ajj fn3- 5, where is the actual mass drift up to the cleaners at the current control cycle; 5- (and is the deviation of mass from the masses to the cleaners at the current control cycle; - nominal weights of the masses to the cleaners.; The obtained value is entered into the functional block 12 for assessing the influence of input maturity on the cleaning of the masses in the battery of cleaners, which determines the correction of the mass concentration value ON the signal coming from the block 10 of the agreement of the nominal weeds and weights of the mass in front of the battery of cleaners o SoCnJ, where x is the correction of the mass concentration on the current control, and a is the tuning factor. The calculation is entered into the functional unit 14 for calculating the mass concentration. The unit 11 for the mismatch of a given weed and weights for the mass after the battery of cleaners determines the deviation of the actual weed of the mass from the weights of the mass given by the signal coming from the meter 9 supplied from the tanks of the cleaning unit 6 to pipeline 7 f by comparing with the given weedness value of 5Sp 5fGp -5zdd, where Sfh is the deviation of the weediness of the mass after the battery will clean up lei at the current control cycle; 2f and - the actual weights of the masses after the battery cleaner on the current control cycle; S ead is the specified mass impurity. . The obtained value is entered into the functional unit 13 for estimating the effect of non-measurable disturbances on the cleaning process, which determines the correction of the concentration value by the signal coming from the unit 11 of the mismatch of the given weed and weedness after the battery of cleaners, x CfiJ XxrnHj + a SfnJ-otjSCM- iJ, where X2fn-f) is the correction of the concentration value at the current and previous control cycles; clean up the weeds of the mass after the battery; clean up the leaks at the previous control cycle; a, 2 and a, are the coefficients of tuning. The obtained value is entered into the functional unit 14 for calculating the mass concentration, which determines the task of the mass concentration controller 15 by signals, received from the unit 13 for estimating the effect of unmeasured disturbances and unit 12 for estimating the effect of input dampness, cleaning the mass in the battery cleaners, as well as taking into account the nominal value of the mass concentration and the restrictions imposed on the value of the task for the concentration of CpCnJ C oy, + x fnJ + X2 fnJ, where Cf is the calculated value of the concentration of the concentration on the current control cycle; The nominal value of the concentration and, if, CGF, if CpfnJ Cn, -, then Cfn, if .Cpfn, then trin max value of concentration; - the task of concentrating on the current control cycle. The obtained mass concentration value as a task is fed to the installation of the mass concentration regulator 15 supplied via conduit 4 and the concentration measured by the meter 16, and the resulting concentration value is entered into the functional unit 17 for calculating the mass flow rate, i.e. into the circuit at the mass flow rate. The mass flow control loop includes: a mass flow rate calculation functional unit 17, the input of which is associated with the output of the mass concentration calculation functional unit 14, a mass flow controller 18, the first input of which is connected to. the output of the mass flow calculation function block 17, and the second input is connected to the mass flow meter 19 supplied via conduit 4 to the purifier battery 5, the output of the regulator 18 affects the mass flow of the same conduit. Functional block 17 for calculating the mass flow determines the required mass flow applied to the battery of cleaners by a signal coming from block mass mass calculation unit 14 taking into account a given mass mass through air-dry fiber, hall QCnjz, Gdw where Gt is the mass flow setting for the current control tact; the set value of the performance over the AIR111 dry fiber "The obtained value is fed to the functional unit 20 for calculating the number of cleaners and as a task it is fed to the installation of the mass flow controller 18 running through the pipeline 4 and measured by the flow meter 19, providing the most specified mass flow rate. Purifier control circuit includes: functional

The unit 20 for calculating the number of cleaners in which is connected to the output of the mass flow calculation functional unit 17, the purifier activation controller 21, whose input is connected to the output of the purifier calculation function unit 20, the outputs of the regulator 21 affecting the battery of the purifiers 5-.

Functional unit 20 for calculating the number of cleaners from c the et the required number of cleaners required in operation based on a signal from the functional unit 17 for calculating the mass flow with a given throughput of an individual cleaner

Lgm

where Ntn is the number of cleaners

on the current control cycle;

fl is the throughput of 10 separate cleaners.

The value obtained as a reference is fed to the installation of the purifier inclusion controller 21.

Claims (1)

METHOD OF AUTOMATIC CONTROL OF THE FIBER SUSPENSION CLEANING PROCESS in centrifugal cleaners by stabilizing the flow of suspension entering the cleaners is distinguished by the fact that, in order to improve the quality of the fibrous suspension cleaning, the mismatch in weedness between the measured and nominal values to determine between the measured and predetermined values of weed after cleaning and depending on the obtained values of the mismatch, the concentration of the suspension entering the cleaning is changed, the last then adjusted slurry flow entering the cleaner, then according to the flow value of the slurry modify the number of working § cleaners.