SU1174718A1 - Method of automatic monitoring of bloating material calcination process and apparatus for accomplishment of same - Google Patents

Abstract

1. The method of automatic control of the process of firing intumescent materials by author. No. 970068, characterized in that, in order to improve the quality of control, the parameter characterizing the pyroplastic state of the calcined material is measured. The maximum value of the firing temperature depends on the parameter characterizing the pyrocastic state of the material to be baked, and the value of the increment of the frequency of rotation of the furnace is adjusted depending on the deviation of the bulk density I of the finished product from its (L acceptable maximum value).

Description

90

2. The device for automatic control of the process of firing intumescent materials by author. No. 970068, characterized in that it is equipped with a sensor of the oplastic state of the calcining material, the output of the averaging unit is connected to the third input of the pulse generator, and the sensor of the pyroplastic state of the calcining material is connected to the third input of the regulator of the calcination temperature.

This invention relates to the automation of the production of intumescent building materials (expanded clay, ash gravel, etc.), mainly in rotary and ring rotary kilns with baking preparation.

According to the main author, St. 970068, a method is known for controlling the process of firing intumescent materials, which consists in measuring and stabilizing the bulk density of the most mass fractions of a ready product by affecting the firing temperature by changing the fuel supply, as well as changing the rotation frequency, for example, periodic in the direction of its increase to the output of bulk density beyond the specified limits and the subsequent reduction of the frequency of rotation of the furnace to the occurrence of the bulk density within the specified limits. When the kiln rotation frequency is changed, a corresponding correction is also provided for the supply of the semi-finished product to the kiln and the introduction of a preemptive corrective effect on the firing temperature ij.

. According to the main author. St. A device for implementing this control method is known, which contains a finished product bulk density meter connected through a series-connected comparison unit and a correction regulator input of a regulator of a firing temperature stabilization circuit (circuit) also contains a thermal sensor and a regulator on the fuel line, connected via a standard circuit with a temperature controller, as well as a bulk density adjuster connected to the second input of the comparison unit. In addition, a control device is introduced into the device, to the inputs of which the outputs of the comparator unit and the bulk density adjuster are connected, as well as frequency controllers

rotation and supply of the semi-finished product and the correction unit, the inputs of which are connected to the output of the control device. The control unit contains an averaging unit, connected

through a serially connected driver, a logic unit and a converter to the limiter input, the driver output is also connected to the input of a pulse generator, the output of which is connected to the second input of the logic unit, the output of the comparison unit being connected to the input of the averaging unit, and output of the bulk density setting device second input shaper l.

A known device implements a search method for controlling the firing process, which establishes the maximum possible

this technological situation of the chemical-mineralogical composition of the raw material and the physicomechanical properties of the semifinished product, the frequency of rotation of the furnace and, accordingly, the supply of the semifinished product with

compliance with the quality requirements of the finished product and thereby ensures an increase in furnace productivity.

However, in the known method and control device, the magnitude of the rotational speed increments is not related to the deviation of the actual bulk density of the finished product from its allowable maximum value, which, when tuned to small increments, unjustifiably delays the system’s output to the maximum possible rotational speed. Tuning 3 to relatively large increments in the frequency of rotation of the furnace may result in overshoot of the inadmissible excess bulk density of the finished product to its allowable maximum value, which reduces the uniformity of the finished product regulated by the standard. In addition, in the known method and apparatus, there is no limitation of the calcination temperature, as a result of which during the process of regulating it in order to stabilize the bulk density within the prescribed limits, the process can reach the region of excessively high calcination temperatures at which the thermal agglomeration of the calcineable material begins. This can cause a profound disruption of the firing process with the need to intervene in the course of the process from the side of the furnace driver. Thus, these drawbacks of the known method and device reduce the quality of control of the calcining process. The aim of the invention is to improve the quality of control. The goal is achieved in that according to the method of controlling the firing process of the intumescent materials, a parameter characterizing the pyroplastic state of the firing material is limited, the maximum firing temperature value is limited depending on the parameter characterizing the pyroplastic state of the calcined material, and the furnace rotation frequency increment in Depending on the magnitude of the deviation of the bulk density of the finished product of its permissible maximum value. In addition, the device ystvo obzhi automatic process control. A hectare of intumescent materials is supplied with a pyroplastic state sensor of the material being burned. The output of the Averaging Unit is connected to the third input of the pulse generator, and the pyroplastic state sensor of the burning material is connected to the third input of the firing temperature reg-ul Tctpa. The drawing shows a block diagram of an apparatus for implementing a control method. The device contains a kiln 1, a measuring instrument 2 of the bulk density of the finished product with a device for distributing its most massive fractions, a comparison unit 3, and a bulk density setting device 4, a correction regulator 5, a regulator 6, a stabilizing temperature stabilization circuit, containing also a thermal sensor and a regulating organ on a fuel line, a control device 7, which includes averaging unit 8, a driver 9, a logic unit 10, an adjustable pulse generator 11, a converter 12 to limiter 13, a controller 14 and 15, respectively, of the rotational speed of the furnace and the supply of the semi-finished product, which are the stabilization circuits of the respective parameters and contain the necessary functional elements and sensors, a correction regulator 16 (dynamic communication unit), and also a sensor 17 of the pyroplastic state of the calcined material (position sensor guide device of the azry-boot machine). The method is carried out as follows. At the exit of the kiln I, meter 2 controls the bulk density of the most mass fractions of the finished product. After comparing the signals of the meter 2 and the setting unit 4 of the bulk density in block 3, the error signal is sent to the controller 5, which corrects the setting of the firing temperature controller 6, which is the standard contour of stabilizing the firing temperature by the impact on the fuel supply by impulse from thermal sensor (thermocouple, pyrometer). If the current value of the density of the density is greater than its specified value and the error signal is greater than the dead zone of the correction regulator 5, the last signal is the correction for lowering the firing temperature, otherwise it will decrease. Thus, by means of this cascade scheme, the bulk density of the finished product is stabilized by changing the x-myco-mineralogical composition of the raw material and the physicomechanical properties of the semi-finished product. The range of permissible deviation of the bulk density from the specified value is determined by the standard regulated uniformity indicator — the coefficient of variation in bulk density and for claydite is + 15%. During the operation of the control system, the output of the bulk density of the finished product beyond the lower preset limit can always be compensated by a corresponding decrease in the firing temperature. At the same time, with deep disturbances of the process, according to the parameters of the raw material and semi-finished product, which sharply reduce the swelling capacity and increase the bulk density of the finished product, its stabilization within the specified limits by increasing the firing temperature may not be achieved. This is due to the fact that at excessively high temperatures, due to the occurrence of a melt on the surface of the grains of the material being calcined (the pyroplastic state of the material), its thermal agglomeration begins - the formation of welded goats, which is a deep disturbance of the burning process and may require an emergency , turn off chi. The prevention of emergency situations in the circuit includes a sensor 17 of the pyroplastic state of the burning material, which during the experimentally determined limit value of this parameter enters a restriction signal either directly into the burning temperature controller or through an intermediate relay turns off the circuit of the regulator electrical actuator ( flaps) on the fuel line and thereby prohibits its movement in the direction of increasing the fuel supply. At the same time, a warning is given to the driver. In relation to rotating bar furnaces, the operation of the sensor 17 of the pyroplastic state of the calcined material can be based on the following well-known principles: from the elevation of the material raised by the furnace lining by the photoelectric or radioisotope method, as well as by measuring the current of the driving motor, including representation of the characteristic spectrum of its oscillations. For annular rotary kilns equipped with finished-product aerial-boosters with an automatic performance control system (pressure) of a blower fan, the force of the auger-actuator interacts with a bakeable material as a pyroplastic sensor as a sensor of the pyroplastic state. switch of its electric actuator. The force of interaction of the amateur piping material, as well as the performance of the blower fan that is installed in accordance with it, dramatically increases during the agglomeration of the material, and, therefore, are indirect parameters characterizing the pyroplastic state of the ma-. t.eriala The position sensor must be adjusted to trigger the limit switch in the position of the guide vane, a corresponding increase in the fan capacity by 1.2-1.5 times compared to the nominal one. Stabilizing the bulk density of the finished product is only one of the functions of the control system. Its other function is to maximize the kiln's performance using for this second most important control effect on the process — kiln rotation speed (for ring rotary kilns, hearth rotation frequency), which sets the firing time. It is known that the optimal firing time is determined by the changing, during the operation, chemical and mineralogical composition of the raw material, as well as the fractional composition and structural and mechanical properties of the semi-finished product. By setting the maximum possible rotational speed of the furnace at a constant filling ratio to ensure a given value of the bulk density of the finished product, you can achieve the highest productivity of the furnace. This task, based on search management methods, is solved in the following way. The error signal from the output of the comparison unit 3 is fed to the input of the control device 7, where the average of the unit 8 suppresses random fluctuations and extracts the main signal. The filtered error signal and the bulk density setting device 4 are fed to the driver input 9, which realizes the functional dependence of the maximum value of the bulk density of the finished product within a predetermined (average) value Y, 0d, and results in a normalized signal when this value is exceeded. This signal, as well as the signal from the generator of 11 pulses in the form of a series of pulses, is fed to the inputs of logic block 0. The algorithm of the functioning of logic block 10 is presented in the table. Note. + - signal presence, .0 - no signal. Directions of the control action correspond to different cavities of the output modulated signal block 10, I. The pulse output signal of the logic unit 10 is converted by the converter 12 (by the integrator) into a single DC signal, given as a correction through the limiter 13 to the inputs of the rotational speed controllers 14 and the feed. Nor is the furnace semi-finished product 15. The regulators 14 and 15 are the contours of the stabilization of the corresponding parameters and contain the necessary functional elements and sensors. The limiter 13 limits the output signal of the converter 12 to a predetermined minimum and maximum in order to prevent emergency operation of the furnace when there is a possible malfunction of the control device. The time interval between the series of pulses produced by the generator 11, i.e. the frequency of introducing tuning effects on the frequency of rotation of the furnace, is determined by the experimentally determined dynamics of changes in disturbing effects on the process. Roughly, the magnitude of this time interval can be received in 2-6 hours. Its task is carried out by a temporary element included in the generator. 11 pulses, or an external time control unit. The parameters of the pulses produced by the generator 11, within the series, are varied (modulated) as a function of the absolute value of the error signal supplied from the output of the averaging unit 8 to the second input of the generator P. Amplitude pulse or pulse width may occur (SH) modulation of this signal. Moreover, the modulation characteristic of the generator 11 is formed in such a way that, with an increase in the error signal, an increase in the modulated parameter of the output pulse sequence, for example, for AIM, is their amplitude. Thus, the magnitude of the increments (both signs) of the signal for setting the rotation frequency of the furnace formed by the converter 12 changes, for example, proportional to the deviation of the bulk density of the finished product from its allowable maximum value. In particular, for circular rotary kiln kilns when the bulk density of claydite varies from 0.74 of the maximum value of the maximum value. The magnitude of the increments (positive) of the rotation frequency of the furnace bottom is reduced from 10-30% to 0-5% of its average value. When changing the bulk density in the range from 1.1-1.2 from the maximum value of V to the maximum value of the increment value (differential) of the rotation frequency of the bottom, it is advisable to reduce its average value from 20-30 to 5-10%.

The pulse repetition period within the trimmer series is set depending on the dynamic properties of the object (approximately 10–20 min), and their length is much shorter than the repetition period. During operation, a situation may arise when, during the period when introducing sub-structural influences with deep disturbances of the process, the stabilization circuit of the bulk density of the finished product does not compensate for disturbances and the value of this parameter is beyond the allowable maximum value. With a circuit for eliminating such a possibility, the signal of the generator 9 is also fed to the third input of the pulse generator, ensuring in this case its forced start (therefore, the table does not contain a combination of signals O,). At the same time, a control signal is given to reduce the rotation frequency of the furnace and thus create conditions for

stabilization of the bulk density of the finished product corresponding contours. When changing the frequency of rotation of the furnace (for annular rotary furnaces, the frequency of rotation of the hearth) and, accordingly, the supply of the semi-finished product, disturbances in the temperature mode of the furnace are introduced. To compensate for these disturbances, a corrective regulator 16 (dynamic communication unit) is fed forward cis by: | 1 to temperature regulator 6 in kiln transitional modes of rotation.

Thus, the device implements the proposed control method with dependent search, in which the rapid exit of the system to the region of the maximum possible frequencies of rotation of the furnace, i.e. decrease losses for the search, as well as a corresponding increase in the productivity of the furnace. In addition, the control system's ability to stabilize the bulk density of the finished product is enhanced, and, thus, its uniformity indicators are improved. The estimated increase in productivity of the lightweight kiln is 5-7%. .

Claims (2)

1. The method of automatic control of the process of firing intumescent materials by ed. No. 970068, characterized in that, in order to improve the quality of control, measure the parameter characterizing the pyroplastic state of the material to be fired, limit it to (53) 66.041.9 (088.8) (56) USSR Copyright Certificate No. 970068, cl. F 27 D 19/00, 1982. (54) METHOD FOR AUTOMATIC CONTROL OF THE PROCESS OF FIRING OF REINFORCED MATERIALS AND DEVICE FOR ITS IMPLEMENTATION,. the maximum value of the firing temperature depending on the parameter characterizing the pyroplastic state of the fired material, and the increment of the rotational speed of the furnace is adjusted depending on the deviation of the bulk density of the finished product from its permissible maximum value 2. Device for automatic control of the process of firing intumescent materials according to ed. No. 970068, characterized in that it is equipped with a piDoplastic state sensor of the calcined material, the output of the averaging unit being connected to the third input of the pulse generator, and the pyroplastic state sensor of the calcined material is connected to the third input of the calcining temperature regulator.