SU1734821A2 - Method of automatic control of active grain ventilation - Google Patents

Abstract

Usage: in agricultural production, in particular in the grain processing industry. SUMMARY OF THE INVENTION: Control the amount and temperature of the air supplied to the dryer by varying the capacity of the fan and connecting the heater sections. The equilibrium air humidity is determined. The capacity of the fan and the number of connected sections of the heater are controlled by the difference between the values of the set and the obtained equilibrium humidity. Set the operating time of the fan with the maximum performance depending on the interval of possible exceeding the maximum allowable difference of the obtained and specified equilibrium humidity. 1 il.

Description

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The invention relates to the agricultural production, in particular to the grain processing industry, and is an improvement of the known method according to the authors. St. USSR № 1423150.

A known method of automatically controlling the process of active venting of grain, which consists in measuring the relative humidity and air temperature at the inlet and outlet of the grain layer, determines the equilibrium humidity by measured values, and controlling the performance of the fan and the number of connected sections of the air heater is carried out by the difference between the set and obtained equilibrium humidity values.

The known method provides for an increase in the fan capacity when the difference between the equilibrium humidity value determined by the air parameters at the outlet of the grain layer and the value of the specified standard moisture content of the grain is higher than the specified one. The equilibrium humidity determined by the parameters of the air at the exit of the grain layer corresponds to the humidity of the output layers of the grain (10 ... 15 cm), and the output layers begin to dry at the very last turn (because when passing through the interleaved layers of grain the atmospheric air is saturated with moisture and drying of the output grain layers does not occur). Thus, the decrease in the value of the equilibrium moisture content determined by the output parameters of the drying agent, and consequently, the decrease in the difference between this value and the specified value of the equilibrium moisture will occur only when the drying is completed. The main

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the grain mass will dry by this time and the average moisture content of the grain over the layer will be equal to or even less than the specified value. This is due to the fact that during the day the atmospheric air takes on such parameters (relative humidity and temperature), that when ventilating with this air, the input layers of the grain dry out (their humidity becomes lower than the required standard).

An increase in drying unevenness is observed. Overdrying of grain leads to deterioration of its seed qualities and unproductive expenditure of energy.

Therefore, a disadvantage of the main method is an increase in the unevenness of drying of the grain layers and an increase in the energy consumption for drying while increasing the productivity of the fan by the difference between the set value of the equilibrium moisture and the value of the equilibrium moisture determined by the air parameters at the exit of the grain layer.

The purpose of the additional invention is to reduce the uneven drying and energy consumption for its implementation.

This goal is achieved by setting the maximum allowable difference of the obtained and specified equilibrium humidity, comparing it with the current difference, setting the intervals of possible exceedances, and changing the fan performance to the maximum level when the current difference exceeds the specified maximum allowable difference, and the operating time of the fan with maximum performance is set depending on the interval of possible exceeding the maximum allowable spacing the obtained and specified equilibrium moisture.

The drawing shows a functional block diagram that implements a method for automatically controlling active ventilator processes.

The flowchart implementing the method consists of four contours. The first circuit includes a control object 1, from the output of which signals are simultaneously sent to the temperature sensor 2 and the relative humidity sensor 3, the outputs of sensors 2 and 3 are connected to the inputs of the equilibrium humidity meter 4, the output of which is connected to the first input of the comparison unit 5, the second input Comparison unit 5 is connected with the first output of the equilibrium humidity setting device B, the first output of the comparison unit 5 is connected with the first input of the switching device 7, the second output of the unit 5

the comparison is connected with the first input of the comparison unit 8, the second input of which is connected with the output of the setpoint 9 of the maximum permissible difference obtained and specified equilibrium humidity, the output of the comparison unit 8 is connected to the input of the multichannel software-time device 10, the output of which is connected to the second input of the switching device 7, the output of the switching device 7 is connected to the inlet of the ventilation unit 11, the output of which is connected to the inlet of the heater 12, the outlet of the heater 12 is connected to the input of the control object 1.

5 The second circuit consists of a heater 12, the output of which is connected to the input of the temperature sensor 13 and the input of the sensor 14 relative air humidity, the outputs of the sensors 13 and 14 are connected to two inputs

0 the equilibrium moisture meter 15, the output of which is connected to the first input of the comparison unit 16, the second input of the comparison unit 16 is connected to the second output of the setter 6, the output of the comparison unit 16 is connected to the input

5 heater 12. The third circuit includes a ventilation unit 11, the output of which is connected to the inlet of the heater 12, the outlet of the heater 12 is connected to the input of the temperature sensor 13 and the input of the sensor 14 relative humidity of the air, the outputs of the sensors 13 and 14 are connected to the equilibrium meter input humidity 15, the second output of which is connected to the first input of the comparator block 17, the second input of the block 17

The comparison unit 5 is connected to the third output of the setting device 6, the output of the comparison unit 17 is connected to the inlet of the ventilation unit 11.

The fourth circuit includes a control object 1, the output of which is connected to the input of the temperature sensor 2 and to the sensor 3 input of relative air humidity, the sensors 2 and 3 outputs are connected to two inputs of the equilibrium humidity meter 4, the output of which is connected to the first block input

5 5, the second input of the comparison unit 5 is connected with the first output of the setting device 6, the third output of the comparison unit 5 is connected to the input of the ventilation unit 11, the output of which is connected to the input of the heater 12,

0 whose output is connected to the input of the control object 1.

A method of automatically controlling the process of active venting of grain is carried out as follows. Za5 sensor 6 set the value of the standard, the required humidity (for wheat, barley, etc. -14%). After the grain is loaded, it is ventilated. At the input of the control object 1, sensors 2 and 3 monitor the temperature and relative humidity of the air, signals from these sensors are fed to the inputs of the equilibrium moisture meter 4, from its output the signal is fed to the first input of the block 5 and compared with the signal which supplies to the second input of the comparison unit 5 from the first output of the setting device 6, if the difference signal at the output of the comparison unit 5 corresponds to the excess humidity of the ventilated grain, measured by the meter 4 equal to Ovesnov humidity of the conditioned, 6%, then the difference signal leads to:

- to increase the productivity of the ventilation unit 11 (along the contour 4);

The difference signal from the output of the comparison unit 5 is subtracted from the setpoint signal

9 in block 8 of the comparison and, depending on the result of the comparison, in the program-time device 10, the response time of the switching device 7 is selected. The program-time device 10 is set in advance, its different channels have different response time values. (For example, when a difference signal at the output of the comparator block 8 is 0-3% humidity, the switching device 7 should work after 6 hours; when the difference signal at the output of the comparator block 8 is 3-6% humidity, the program-temporary device 10 gives a signal for the switching of the switch device 7 after 10 h). The difference between the equilibrium moisture content of 6% and the intervals of its possible exceedance (0–3%, 3–6%) were chosen from considerations of the efficiency of the system and the preservation of the processed grain. Thus, when the moisture content of wheat grain is greater than the target (14%), the duration of its safe storage is 12 days; if it exceeds 3%, the period of safe storage is 25 days.

Smaller fragmentation of the possible overshoot interval complicates the system without significantly increasing efficiency.

After the time interval selected by the program-temporary device 10 has expired, the program-temporary device issues a command to the operation of the switching device 7, which, if activated, decreases the performance of the ventilation unit 11. After the performance of the ventilation unit 11 decreases, it can no longer be increased. , because the program-temporary device 10 does not return to the initial state (to a new stage of timing) until the ventilation process is completed, and the switching device GUSTs 7 blocks the passage of the signal along the contour 1

to increase the performance of the heat ventilation unit 11.

If the humidity of the ventilated grain, measured by the equilibrium moisture meter 4, does not exceed the conditional one by the specified value (6%), then the performance of the ventilation unit 11 along circuit 1 does not increase.

When the grain is actively ventilated, atmospheric air is used, the temperature and relative humidity of which are controlled at the outlet of the heater 12 by sensors 13 and 14. The signals from the senders 13 and 14 are fed to the inputs of the equilibrium moisture meter 15, from the first output of which the signal is fed to the first input of the comparator 16, the second block of the input 16 of the comparison is given a signal from the second output of the setting device 6. If the equilibrium humidity of the air exceeds the conditioned humidity of the grain, then the difference signal from the output of the block 16 of the comparison gives the command Turning sections of heater 12 to reduce the equilibrium relative humidity at the outlet 12. The heater circuit 2 is involved throughout the venting process.

Circuit 3 works as follows. At the outlet of the heater 12, the temperature and relative humidity of the air are monitored by sensors 13 and 14, respectively, sensors 13 and 14 are connected to two inputs of the equilibrium moisture meter 15, from the second output of which the signal is fed to the first input of the comparator unit 17, to the second input of the comparator unit 17 from the third output of the setter 6. If the equilibrium moisture measured by the equilibrium moisture meter 15 is less than the standard moisture of the grain by 3% or more and the sections on the air heater 12 are not connected at that time, then the comparison unit 17 is a command to increase the productivity of the ventilation unit 11. When the difference is less than 3%, the comparison unit 17 gives a command to decrease the air supply and it remains constant until the completion of drying,

The need to complete the drying is defined as follows (circuit 4). At the output of the control object 1, the temperature and relative humidity of the air are monitored by sensors 2 and 3, respectively, sensors 2 and 3 are connected to the inputs of the equilibrium humidity meter 4, the signal from the output of which is fed to the first input of the comparison unit 5.

The second input of the comparison unit 5 is given a signal from the first output of the setting device 6. In the case when the signal at the output of the meter

4, the equilibrium humidity is equal to the signal at the first output of the setting unit 6, then the grain is considered to be dried to standard humidity, and the comparison unit 5 on the fourth channel gives a command to turn off the ventilation unit 11. The ventilation process stops.

Claims (1)

The invention The method of automatic control of the process of active grain ventilation according to auth. Ms 1423150, characterized by the fact that, in order to reduce the unevenness of grain drying and energy consumption, they set the value of the maximum permissible difference of the obtained and specified equilibrium humidity, compare it with the current difference, set the intervals of possible exceedances, and change the fan performance to the maximum level when the current difference exceeds the specified maximum difference, and the operating time of the fan with maximum performance is set depending from the interval of possible excess of the maximum allowable difference of the obtained and specified equilibrium moisture. 15