SU1615511A1 - System for controlling grain drying process - Google Patents

Abstract

The invention relates to a technique for drying agricultural products and can be used to control the process of drying grain, mainly seed at post-harvest processing points. The aim of the invention is to improve the quality of drying by stabilizing the final moisture content of the grain. The system for controlling the grain drying process contains sensors 1 of grain temperature, switch 2, normalizing converter 3, unit 4 of comparison, block 5 of delay, block 6 of control, block 7 of indication and unit 8 of heating temperature. 2 hp f-ly, 3 ill.

Description

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The invention relates to a technique for drying agricultural products and can be used to control the process of drying grain (mainly seed) at post-harvest processing points. The aim of the invention is to improve the quality of drying by stabilizing the final moisture content of the grain.

FIG. 1 is a block diagram of the proposed Grain Drying Process Control System I; in fig. 2 - diagram of the delay unit; in fig. 3 is an example of a delay block.

The grain drying control system (Fig. 1) contains serially connected product temperature sensors 1, switch 2, normalizing converter 3, comparator unit 4, delay unit 5, control unit b, display unit 7, the inputs of which are connected to the normalizing converter outputs 3 and the delay unit 5, the setting unit 8 of the heating temperature, the output of which is connected to the input of the comparison unit 4, while the delay unit 5 contains nodes 9.1-9. And meter control, where n is the number of temperature sensors used, counters 10.1 are Y.l. from the entrances : 9.1-9.p outputs of which are connected control nodes I.

 Nodes 9.1-9. “The controls each have three inputs a, b, c. In this case, the input a of each of the nodes 9.1-9. P is connected to the output of the unit 4 of the comparison, I inputs b are connected respectively to the outputs of the switches 2, and inputs to the generator 11 pulses. The outputs of the counters 10.1 - 10.L are connected respectively to the inputs of the logic circuit OR 12.

Nodes 9.1-9. L include each I three logical circuits AND 13, AND 14, And 15, inverter 16 and trigger 17. The inputs of the circuit 13 and I are respectively the inputs a, b of the nodes I 9.1-9. tt. The input b of the AND 13 circuit is connected to the input of the AND 14 circuit, the second input of which is connected to the output of the inverter 16. The input of the inverter: 16 is connected to the second input of the I 13 circuit; and is the input of node 9.1. The outputs of the circuits 13 and 14 are connected respectively to the inputs of the S- and / -trigger 17, the output of which is connected to the input of the circuit 15, the second input of which is the input to the node 9.1. Input / Trigger 17 is connected to the input of the counter 10.1, and the output of the circuit 15 is connected to the counting input G of the counter 10.1.

The drying process control system operates as follows.

Switch 2 in series, cyclically connects the temperature sensors 1 to the normalizing converter 3.

The output signal of the normalizing converter 3 in the form of a DC voltage proportional to the temperature of the grain is supplied to the display unit 7 and the comparison unit 4. The display unit 7 converts this signal and temperature information.

in the form of a decimal number is displayed on the digital indicators of the display unit 7. The DC input signal is fed to another input of the comparator unit 4 from the setpoint 8 of the heating temperature.

If during the cyclic polling of the temperature sensors 1, the output voltage of the converter 3 exceeds the voltage of the setting device 8, the comparison unit 4 switches the control unit 9 corresponding to the sensor being polled. The switched control unit 9 will ensure the arrival of the pulses of the generator 11 to the input of the counter connected to it.

If the temperature of this sensor does not decrease during a predetermined time setting (set, based on the humidity and temperature of the grain), the output of the counter and, accordingly, the output of block 5 of the delay will send a signal to the blocks 6 and 7. The signal 6 control will reduce the heat supply to the grain mass.

In the course of operation, when interrogating a specific sensor, the comparison unit 4, made, for example, on the comparator 18, controls the logical signal "1 when the input voltage of the setpoint device 8, made, for example, on the potentiometer is exceeded. The presence of the signal "1 at the output of the comparator 18 corresponds to the excess temperature of the grain above the permissible. When polling sensors 1, switch 2 generates a signal-logic circuit AND, which is fed to one of the nodes 9.1-9. Of the control, which is matched to the temperature sensor currently being polled. Generator 1 continuously pulses the nodes 9.1-9.p control.

If during operation the temperature of the grain does not exceed the allowable, at the output of the comparator 18 there will be a signal “O and upon receipt of a signal from the logic circuit And successively to the nodes 9.1-9.rt from switch 2, logic circuits 13.1-13.l, 14.1 - 14.L, 15.1 - 15.Л will form the trigger reset signals 17.1 -17.p. In the absence of a signal from the logic circuit AND from switch 2, the triggers 17.1 - 17.P will maintain the previous zero state.

The outputs of the triggers 17.1-17.p are connected to the inputs of logic circuits 15.1 -15. ", The other inputs of these circuits are pulsed by the generator 11. The outputs of the circuits 15.1-15." Are connected to counters Ш.1 -10.п. In this mode, the generator pulses 11 do not arrive at the counters 10.1 - 0.p, since the signals “O will block the passage of the pulses of the generator 11. The outputs of the counters 10.1 - 10.P are connected to the inputs of the OR circuit 12 and, accordingly, the output of the OR circuit 12 is the signal “Oh, that corresponds to the normal mode of grain drying.

If the temperature of the grain in the zone of action of any sensor, for example, the first, exceeds the permissible one, then when polling this

A sensor at the output of the comparator 18 provides the signal of the logic circuit I. When a signal appears at the outputs of circuits 13 and 14.1, the logic circuit I and the circuits 13.1, 14.1 and 15.1 will form a switch signal of the trigger 17.1 into the unit state. The pulses of the generator 11 will begin to flow to the counter 10.1. If the temperature of the first sensor does not become lower than permissible in subsequent polling cycles of this sensor, the counter 10.1 will continue to count pulses.

The time interval from the beginning of the counting to the appearance of the signal “1 at the output of the counter 10.1 corresponds to the permissible overheating time of this type of grain (3-10 minutes). The duration of this interval is set before the operator starts using the generator frequency controller 11.

When the signal of the circuit AND at the output of the counter 10 appears, this signal goes to the circuit OR 12 and from its output to the display unit 7 and the control unit 6. On this signal, the actuators will be turned on, the heat supply to the pit will decrease and, accordingly, the temperature of the dried grain will decrease.

If the grain temperature exceeded the permissible one was short-lived and in one of the subsequent polling cycles the grain temperature decreased to the permissible one, the signal from comparator 18 will become zero and logic circuits 13.1, 14.1 and 15.1 will generate a signal for switching the trigger to zero and resetting the counter 10.1. In this case, the signal to the control block b will not be received, and the drying process will continue as before.

Introduction to the control system of the delay unit 5, the inputs of which are connected to the switch 2 and the comparison unit 4, and the outputs connected to the inputs of the display unit 7 and the control unit 6, reduces the number of actuator actuations that control the flow of coolant to the dryer , which ultimately leads to a decrease in the uneven moisture content of the grain at the outlet of the dryer, i.e., an increase in its quality.

Execution of the delay unit 5 according to the proposed scheme with the indicated links allows for multichannel cyclical polling of temperature sensors 1, as well as the formation of independent time signals.

Delays on each of the channels. The logic functions performed by the delay unit 5 allow the discharge of the counted time intervals, the length of which is less than the time of thermal stability of the grain.

Claims (3)

1. A grain drying process control system comprising product temperature sensors connected to a switch, the output of which is connected to an input of a normalizing converter connected by an output to a display unit and an input of a reference unit, is a temperature setting device, which in order to improve the quality of drying by the final moisture content of the grain, it additionally contains a time delay block, one input of which is connected to the output of the comparison unit, and the second to the switch, and the outputs are connected to the control unit and control unit eye display. 2. A system according to claim D, wherein the delay unit further comprises meter control units, the number of which is equal to the number of monitoring sensors, a pulse generator and an OR logic, and the input of each of the control nodes is connected respectively to the outputs of the comparison unit, the generator pulses and switch, and the output is connected to counters, the outputs of which are connected to the inputs of the logic circuit OR. 3. The system of PP. 2 and 3, characterized in that each meter control node contains three AND logic circuits, an inverter, a trigger, wherein the first input of the first AND logic circuit is connected to the switch and the input of the second AND circuit, the second input of the first AND circuit is connected to the output of the comparison unit and its output is with the S-input of the trigger, whose input is connected to the output of the second logic circuit AND, the second input of which through the inverter is connected to the output of the comparison unit, the output of the trigger is connected to the first input of the third logic circuit AND, the second input of which is connected to the generator pulses, and the output of the third circuit AND is connected to the G-input of the counter, the / -input of which is connected to the output of the second circuit AND and the output to one of the inputs of the OR circuit.