SU1651061A1 - Automatic control method of hay forced ventilation drying - Google Patents

Abstract

The invention relates to the automation of drying processes with active ventilation of hay can be used in agriculture and allows to intensify the drying process and improve the accuracy of control. For this purpose, in control unit 1, the current value of the relative humidity of atmospheric g of air measured by sensor 3 is compared with the boundary setpoint. Moreover, if the result of the comparison is positive, then the air supply is periodically (to prevent the hay from heating itself). If the result of the comparison is negative, the flow of air (L

Description

The invention relates to the field of drying of hay by active ventilation and can be used in agriculture for designing systems for automated control of hay drying.

The purpose of the invention is to intensify the process and improve the accuracy of control 2

Fig. 1 shows an installation for carrying out the process of drying hay by active ventilation in Fig. 2, a block diagram 3 of an automatic control device for the drying process with active ventilation of hay; Fig. 3 is a block diagram of the control unit, 1 in Fig. 4 is a comparison unit diagram; 3 in Fig. 5 is a block diagram of the analog-to-digital conversion algorithm in the comparison unit; 6 is a flowchart of the process control algorithm for the whole day; FIG. 7 is a plot of the equilibrium moisture content of hay W versus relative air humidity $

A unit for drying hay by active ventilation contains a device 1 of control 9 connected to a fan 4 by a torus 2 and a sensor 3 of relative humidity of the surrounding air, an air distribution unit 4 in the form of a channel on which hay 5.5 is fed

The automatic control device 1 comprises a control block 6 with a group of outputs 7 and 8, a block 9 of comparison with input 10 and output 11, a latch register 12 with a group of outputs 13, a permanent storage device 14, an output matching device 15 with a group of outputs 16 and a reverse - a strong magnetic starter 17.

In order to implement the drying process control algorithm, the control unit 6 is connected to a group of outputs 7 With a register latch 12, which through a group of outputs 13 provides initialization of the permanent storage device 14 connected via a group of outputs 7 to the control unit.

Another group of outputs 8 of control unit 6 is connected to an output matching device 15, which through a group of outputs 16 provides control of a reversible magnetic starter 17 that turns on the engine.

The control unit 6 contains an arithmetic logic unit (ALU) 18 with a group of outputs-inputs 19, a battery 20, an intermediate storage register 21, a command register 22 with an output 23, a command decoder 24 with an output 25, an embedded random access memory 26 of data (RAM ) with input 27, address register 28, clock pulse generator 29 with output 30, timer-counter 31, buffer-lock 32 I / O channels, buffer-lock 33 channels. And the rest and counter 34 commands.

The inputs / outputs 19 of the control unit 6 serve as an information bus for exchanging data between the ALU 18, the accumulator - the torus 20, the intermediate storage register 21, the command register 22, the address register 28, the embedded RAM 26 - data, the I / O channel buffer 32, buffer-lock 33 data channels, timer-counter 31 and counter 34 commands. Moreover, the output 23 of the register of 22 commands is connected to the decoder of 24 commands, the input 27 of the embedded RAM 26 is connected to the register 28 of the address of the RAM, the output 30 of the generator5165

pa clock pulses connected to the timer-counter 3 1.

To implement this technical solution, known technical means can be used.

To implement the method of automatic control of the drying process with active ventilation of hay, the following operations are required: measuring the relative humidity of the ambient air, comparing it with the boundary humidity set recorded by the operator in RAM 26, making a decision depending on the comparison results, automatically changing setpoints after a certain time of ventilation, counting the total time of ventilation and a forced ventilator, connection depending on meteorological their conditions for air heaters, etc.

In order to take into account the necessary reduction in the setpoint of the boundary humidity of the air during the drying process due to a decrease in the equilibrium moisture content of hay, one uses the known graphical dependence of these parameters (Fig. 7), which can be described using an empirical formula that looks like

W -0, + 1.65Cf- 58.

The mean and maximum relative error of the formula for (V 60-85% does not exceed 6.5%.

Using this relationship, it is possible to determine what relative humidity air must have in order to ensure the process of absorbing moisture from the dried hay and at the same time it can be determined what equilibrium

humidity w can be dried

hay at a given limiting air humidity

For example, if the boundary humidity setting is equal to 85, 80, 70 and 65, respectively, the hay can be dried to an equilibrium humidity of 30, 25 18.5 and 17%.

Let, for example, the initial setting of the boundary humidity is chosen equal to 85%.

If the actual humidity of the ambient air is below this set point, then the hay is continuously ventilated for 40-50 hours and then occurs.

five ,-,

five

,

0

automatically changing the limit humidity setpoint to the next value, for example 80%, and continuous ventilation continues again at a real humidity below 80%, etc. until the end of drying after 190-200 h of total ventilation.

If the weather conditions suddenly become unfavorable and the real humidity of the air exceeds the limit value. Continuous ventilation stops, but in order to avoid self-heating of the hay, periodically forced blowing of the hay takes place for an hour. And as the setting of the boundary humidity decreases, i.e. as the hay dries out and the danger of its self-heating diminishes, the interval between blows increases from 3–4 hours at 65–16 hours to 14–16 hours.

With prolonged adverse weather conditions and, accordingly, prolonged forced downtime of the fan, the operator may, in the presence of heaters, dry the hay to a condition with heated air.

In the control device 1, the signal from the sensor 3 is fed to the input of the comparator unit 9, which is a comparator (Fig. 4). The other input 10 of the comparator receives a signal from the control unit 6 — The output 11 of the comparator is connected to the control unit.

Using a comparator, it is possible to realize analog-to-digital conversion of the signal coming from the humidity sensor, i.e. measure the magnitude of this signal using the pulse-width modulation method (or the duty cycle method), based on the fact that if repeated short short-term voltage pulses are applied to the RC circuit, the capacitor ards to some kind of average voltage, since the time constant of the RC circuit is sufficiently large compared to the period of the charging pulse.

In this case, the signal from the humidity sensor through R-C is fed to the input of Tsomparator, while Condator C is charged to the value of the input signal. The comparator compares the voltage values at capacitors C and C .. If the voltage at C t is less than at C-, then a low-level signal appears at the output 11 of the comparator, processing which the P-block

This equals a high level signal, which is fed to input 10, which recharges capacitor C.

If, on the contrary, the voltage on C is more than C, then at the input 10 of the comparator there will be a low level signal and the capacitor C will be discharged.

Thus, with this method, the voltage across the capacitor C is all: the time is compared and approaches the voltage across the capacitor, i.e. Uc and Uex. With this method, the magnitude of the signal can be found quite accurately, measuring the charge and discharge times of the capacitor Cf:

(U h - U0) T

G, +

-and

where u

and,

high voltage (logical 1) | low voltage (logical O); T C - time discharge capacitor

C 9

TЈ is the charge time of capacitor C ,.

 The time T and T are measured using two counters in the control unit, one of which counts T, and the other

the sum of T ,, + T.

(figure 5).

Depending on the relative humidity of the ambient air measured by the sensor 3, the control unit 1 generates a command to turn on the engine of the fan 2, which blows through the air duct 4 hay 5.

The control device 1 operates as follows. Each operation that the control unit performs is identified by a single byte of information, called the command code or operation code. The command is sampled as follows. Initially, the address stored in the command counter 34 is transmitted on the output through the latch register to the streaming memory device, from which the addressed command byte returns to the control unit storing it in the command register 22. The command code recorded in the command register is output on output 2 to a command decoder, where it is decrypted and converted into output signals that control the functions of the ALU 18, the ALU performs arithmetic

0

five

0

five

0

35

0 45 50 5

and binary binary operations: accepts 8-bit data words from one or two sources and generates an 8-bit result controlled by the decoder signals of 24 commands. The ALU 18 can perform addition functions with or without carry, AND operation, W, Exclusive OR, increment (decrement of register contents), cyclic shift to the left, to the right. If the command is two bytes, then the first byte selected from the memory is placed in the register of 22 commands, and the next byte is placed in the register 21 of intermediate storage. After the command is decrypted, the command execution phase begins.

In addition, the ALU 18 performs arithmetic and logical operations on binary numbers, but it also produces feature bits that reflect the conditions arising in the process of arithmetic operations. Depending on the status of the sign bit, transitions are implemented when executing the program, Usually one of the operands with which the ALU operates is contained in the accumulator 20. When performing operations, the accumulator is a register-source of data (contains the operand ) or register-receiver (contains the result). The I / O data and data channel data are usually passed through a battery. The resident memory for online data storage is organized from several 8-bit registers and is used to store frequently required intermediate results. A clock generator 29, coupled to output 30 with timer counter 31, collectively provides for the initialization of the operation of the control device, the counting of external events and the acquisition of precise time intervals.

Thus, with the method of automatic control of the drying process with active ventilation of hay, the current value of the relative humidity of atmospheric air is compared with its predetermined limit value (setpoint), when a positive comparison is obtained, the air is supplied periodically (hay). negative air supply is carried out continuously. Total time

m of air supply is 190-200 hours, and in the period of constant air flow. air glands evenly change the specified boundary value of its relative | moisture content (by 5% every 45-50 hours of total air supply) until it reaches the value of the equilibrium final humidity of hay. With this, during the period of periodic air supply, after each occurrence of the change in the boundary value of its relative humidity, the turn-off time of the fan increases (i.e., hay blowing to prevent its self-heating is less common),

Claims (1)

Invention Formula A method for automatically controlling the drying process with active ventilation of hay by measuring the relative humidity of the atmospheric air, comparing the obtained value of humidity with its predetermined by value and by comparison, the fan is turned on, characterized in that, in order to intensify the process and improve control accuracy, when a positive comparison result is obtained, the air is supplied periodically, with a negative result, the air is continuously supplied 190–200 h, and in the period of constant air supply, the given boundary value of its relative humidity uniformly changes until it reaches the equilibrium value final humidity of hay, and in the period intermittent feeding increases fan failure. h fug.2 ( SchigZ / Begin conversion Vprograms Clear counter Load total time counter T + T2 to detect overflow - counter Comparator 1 Yes Apply positive voltage Increment counter Increment counter Not Conversion complete. Return to the main program ) Not Uc, Ub Apply negative voltage Delay to equalize time FIG. five Measurement of current air humidity Shutdown 1 Fan J TfOObtf.uftnaffKtf the boundary is smoothly at the time of the stop, increasing the burden of the next setpoint ta / w I I old / Met Fan turn-on AQ Yes Not End of the drying process FIG. 6 hell 1 j0 R one YU 60 l 70M30 f, Relative air humidity tpЈ% J FIG. 7