SU1750597A1 - Method for control of tea drying process in drying machine - Google Patents

Abstract

The invention relates to the tea industry and can be applied in control systems for the process of drying tea in a tea-drying machine using computer technology. SUMMARY OF THE INVENTION: The method allows controlling the drying process of tea in a tea dryer, at which the humidity of tea is measured on the output conveyor of the tea dryer and periodically changes the fuel supply to the tea dryer air heater by acting on the actuator in the fuel supply channel. The impact on the actuator is carried out directly from the results of measuring the humidity of the tea, and the subsequent regulation is carried out taking into account the response of the system to this effect, which is reflected in the adjustment of the proportionality parameter d and the exposure time K. 1 il.

Description

The invention relates to the tea industry and can be used to control the drying process of tea in a tea-drying machine.

There is a method of controlling the heat treatment of the tea leaf, at which the temperature at the inlet of the heat treatment apparatus of the tea leaf is measured and the fuel supply to the heater is periodically changed to maintain the desired temperature in the heat treatment apparatus of the tea leaf.

However, the known method does not provide the necessary quality control, for example, by drying the tea, since the granulometric composition and humidity of the tea leaf being processed may vary and, as a result, the moisture content of the tea at the outlet of the tea-dryer will change.

The main indicator of the quality of control of the tea drying process is the constancy of the moisture content of the tea leaving the tea-drying machine, and the moisture content of the tea should not exceed a certain predetermined value. Otherwise, waterlogging of the tea leaves may occur, which may cause damage to the semi-finished tea due to tea mold.

The closest to the present invention is a method for controlling the drying process of tea in a tea dryer, at which the humidity of the tea on the output conveyor of the tea dryer is measured and the fuel supply to the tea dryer heater is periodically changed by acting on the actuator in the fuel supply channel to achieve the specified humidity value cha

Xi

01 Oh

sl o

Xi

The disadvantage of the known method is the reduced accuracy of maintaining the humidity caused by a change in the characteristic of the controlled object. The release of moisture from the allowable control zones causes a deterioration in the quality of the finished product.

The purpose of the invention is to improve the quality of the finished product.

This goal is achieved by the fact that according to the method of measuring the humidity of the tea on the output conveyor, the actuator is directly affected by the results of measuring the moisture of the tea, and the time of the effect on the actuator in the fuel supply channel is determined by the formula

(Uzad-Um) d D Y,

(one)

where K is the time of action on the actuator;

d - proportionality parameter;

Uzad - set point of humidity;

The measurement is the originally measured moisture value.

Then, after the transition period has elapsed, the humidity of the tea on the output conveyor is measured again, the difference D Vj is determined with the permissible value of the control error, and the occurrence of the error signal is determined by the value d

d

TO

Ay

(2)

and set the time of exposure to the actuating mechanism for supplying fuel to the heater by the formula

(Used-U ism),

(3)

If the measured humidity value (Uism) exceeds the specified value (Uzad) by an amount greater than the allowable adjustment limit, then, without stopping the adjustment process, stop the conveyor of the drying machine and the outboard conveyor by the condition t determined by the formula

T a (Uzad-U ism),

(four)

where a is a pre-selected coefficient of proportionality, experimentally established for a given tea-dryer.

Due to this technique, the wetted tea is prevented from getting into the semi-finished tea that is withdrawn from the tea-drying machine, as a result, the quality is improved.

the resulting semi-finished product,

The drawing shows a schematic diagram of one of the possible variants of the device for implementing the proposed method for controlling the drying process.

cha in the tea dryer.

A device for carrying out the proposed method comprises a tea-drying machine 1 with a heater 2 having a channel 3 for supplying fuel. Above the external conveyor 4 of the tea-drying machine 1 a humidity sensor 5 is installed, for example, an infrared moisture meter VDS-201, the output of which is connected to the analog-digital converter 6 (ATCPS5-121), V. Exit

the analog-digital converter is connected to the input of the control computer 7 (of the type EVMS5-12), the output of which is connected to the power amplifier 8. The power amplifier 8 is connected to the actuator 9 installed in the channel 3 for supplying fuel to the heater 2 of the tea-dryer 1. The actuator 9 reacts to the supply of fuel to the heater under the influence of a signal from the power amplifier 8. The remote conveyor 4 and the dryer conveyor (not shown) are connected to a single drive 10, which is also controlled by power amplifier 8.

In accordance with the proposed method, the device operates as follows. Before starting the adjustment process, the tea-drying machine 1 and the associated heater 2 are started up, in

which channel 3 is supplied with fuel (fuel oil). In a tea-drying machine 1, using a suitable conveyor (not shown), the twisted tea is supplied, which, entering the conveyor system of the tea-drying machine 1, passes through the heated zone and is carried out of the tea-drying machine 1 by means of the remote conveyor, for further processing. When the dried tea appears on the remote conveyor 4, the control system is turned on, for which the computer 7 enters data including the specified humidity value of ca (Uzad), the initial value of the parameter portion 5 (d) to determine the time of action on the actuator 9 (K), the initial value of the coefficient of proportionality (a) for calculating the time (t) for stopping the conveyor of the drying machine 1 and the remote conveyor 4, the time of the transition period, etc. After starting the control system with a moisture meter 5 GVA 201 from er cha dissolved humidity value (V meas) at the remote conveyor 4 chaesushilnoy machine. The moisture meter 5 signal, proportional to the measured humidity value in the form of an analog signal, is fed to the input of an analog-digital converter b, where it is converted into a binary code fed to the input of the computer 7. The computer determines the time of action on the actuator 9 by the formula (1 ) and through the power amplifier 8, the actuator 9 is affected, which increases or decreases the fuel supply through the channel 3 to the heater 2 of the drying machine 1 depending on the sign (put severe or negative) mismatch between the specified humidity value of the tea (U3ad) and the measured value (Y meas.).

After the time of the transition period caused by the impact on the actuator 9 (this time is also preset and entered as the source data in the computer), the computer 7 again turns to the analog-digital converter 6 and receives through it the new value of humidity ( ) from the moisture meter 5. Next, the difference (L Y) is determined. It is compared with the allowable value of the control error and, if it does not exceed it, the effect on the actuator 9 through the power amplifier is not performed, i.e. the actuator 9 remains in the same position, otherwise the machine 7 calculates the updated value d by the formula (2) and effects through the power amplifier 8 the actuator 9 during the time determined by the formula (3).

After the transition period caused by the effect on the actuator 9, the adjustment cycles are repeated in the described sequence.

Another feature of this device is that. that if the measured humidity value (Vm) exceeds the specified value (V3ad) by an amount greater than the allowable adjustment limit (this value is also entered into the machine 7 in the source data system), without stopping the adjustment process, the computing machine 7 outputs through the power amplifier 8 stop command

the drive 10 of the conveyor of the tea-drying machine 1 and the remote conveyor 4 for a time r determined by the formula (4). This makes it possible to exclude the receipt of over-humidifying - a little bit for further processing, which has a positive effect on the quality of tea as a whole.

PRI me R. The computer 7 introduced a specified value of humidity and experimentally found value of the proportionality parameter. After that, the VDS-201 infrared moisture meter measures the current value of the humidity of 11%. The computer determines the time

5 influences the K - -15 actuator and affects the IM (opening) for 15 s.

After 15 seconds, the moisture is measured again, i.e. D.

0 Due to the fact that the difference (-3%) exceeds the allowable value of the adjustment error (± 1%), then the adjusted value is calculated, 5, then, 5, i.e. the impact on the actuating mechanism is carried out in the same direction (opening) for an additional 22.5 s.

To calculate the stopping time of the conveyor system, without interrupting the adjustment process, computer 7 is also entered

0 experimentally determined coefficient of proportionality a -6 and calculate g 30 s, i.e. the dryer conveyor is stopped for 30 seconds.

5 Thus, the proposed method for controlling the drying process of tea ensures that the specified humidity of the tea at the output of the tea-drying machine is maintained without the use of additional

0 temperature control loop, which simplifies the control method.

In addition, in the proposed method, the removal of the moistened tea from the tea-drying machine is excluded, which improves the quality of the semi-finished tea.

Claims (1)

Claims The method of controlling the drying process of tea in a tea-drying machine, which involves measuring the moisture content of the tea on the output conveyor, is characterized in that, in order to improve the quality of the finished product, the actuator directly feeds the fuel 5 according to the results of measuring the humidity of tea, the time of action on the actuator in the fuel supply channel is determined by the formula K- (Uzad-U „zm d -AY1. where K is the time of action on the actuator; d - proportionality parameter; Yzad is the specified humidity value; At em - the initial measured value of humidity, then, after the transition period expires, the humidity of the tea on the output conveyor is measured again, the difference A Y is determined, compared to the allowable value of the control error, and the occurrence of the error signal is determined by d d TO DU-5Y and set the time of impact on the executive mechanism for supplying fuel B 10 heater according to the formula (Uzad-).