SU204248A1 - METHOD FOR AUTOMATIC REGULATION OF DRYING GRAIN IN DRYING UNITS - Google Patents

Description

Methods are known for regulating the processes of a dryer in gas recirculation grain drying units, providing for two circuits; the circuit for stabilizing the heating temperature of the grain, regardless of its moisture content, the quality of gluten, and the circuit limiting the flow of underdried grain to the warehouse and sending it for additional drying to the specified humidity.

However, during the operation of the drying unit with full grain recirculation due to a sharp decrease in the moisture gradient between the grains in the mixture of wet and recycled grains, the contact mass transfer in the hopper decreases, the migration of moisture to the grain surface decreases, which leads to a decrease in unit productivity. In addition, studies of this circuit on an analog electronic model have shown that with this method of stabilizing the moisture of dried grain, periodic overdrying of grain is inevitable. Reducing the productivity of the unit or overdrying the grain leads to a significant increase in the cost of a ton of dried grain.

The drawing shows a block diagram of an automatic control system (ATS) according to the proposed method. It consists of the following automatic control loops,

The first circuit of the SAR regulates the temperature of the grain at the outlet from the heating chamber I by changing the fuel consumption supplied to the firebox depending on the humidity of the grain entering the dryer and the quality of gluten. The circuit includes a control device /; temperature sensor 2, actuator 3, sensor of moisture meter 4, secondary device of moisture meter 5 with a rheostat or position setter, unit 6 of the permissible heating temperature of the grain depending on the quality of gluten.

The second circuit of the SAR provides stabilization of the desired humidity of the dried

grain, regulating the moisture content of the mixture recirculating and drying the grain by changing the ratio of the costs of these flows, depending on the amount of moisture removed in one pass of the grain through the head of the moisture meter 5; summator 12 of actuators J3, and ancillary mechanisms M and 15; dual gate valves 16 and 17 regulating grain consumption, regulating grain valve 18 and following devices 19 and 20, which regulate the flow valve of grain 18 and 17.

The third SAR circuit ensures the stabilization of the weight flow of the grain mixture through the heating chamber and the load of the recirculation norium by changing the flow rate of the recirculating grain and the grain for drying at the entrance to the noria.

The need for this contour is dictated by the presence of significant disturbances in the consumption of grain entering the noria. These disturbances are caused by changes in natural weight, moisture, grain weed, etc.

The circuit consists of the control device 21, the power sensor 22 of the electric drive 23, the recirculation elevator 24, the actuators 25 and 26, and the follower device 27.

The principles of synthesis and the operation of the circuits of the proposed ATS are as follows. The setpoint of the regulating device setter / in the temperature control circuit of the GM-ssi grain is determined by the quality of the gluten and the humidity of the grain supplied to the dryer. In this case, if the dependence of the allowable heating temperature of the grain Qdop on the humidity Wi is monotonous, the task is determined by a rheostatic setting device (with a corresponding characteristic) of the secondary device of the moisture meter 5. At the usually recommended discrete values, the task is determined by constant resistances, which, depending on the value W corresponds to 1c: the positioning output of the same secondary device is switched.

Unit 6 is a set of three: different resistances, which, depending on the quality setting of gluten (strong, normal or weak), are alternately connected in series to the setting circuit of the secondary device 5. Thus, the setting value of the regulating device 1 determines the sum of the resistances of the setting meter of the moisture meter and gluten quality.

When developing a device for automatically determining the quality of gluten grains in the stream, the setting device 6 must be the regulating output of this device. However, the manual change of the setpoint of the setter 6, according to laboratory analysis, does not complicate the maintenance of the unit, since the quality of gluten of batches of grain delivered during the harvesting period to this drying unit, as studies have shown, varies quite rarely. Deviations of the actual temperature value of the grain Q from the setpoint Qdop are eliminated by the regulating device by a corresponding change in the consumption of fuel burned in the furnace of the unit.

the results of the research of aggregates, which made it possible to determine the functional dependence of the magnitude of the moisture removal AW in one pass of the grain mixture through the dryer on a number of key process parameters.

When the actual moisture content of the grain mixture deviates from a predetermined value, for example, when it rises relative to the regulating effect, the actuator 13 covers the corresponding gate valve 17. At the same time, through the next device 19, the actuator 14 opens the back valve 16. Thus, the ratio between recirculating and the grain to be dried changes until recovered

WCM equality si

Simultaneously with the valve 17 through the follower device 20, the actuator 15 covers the valve 18. This makes it possible to maintain an approximate equality of consumption of the incoming and dried grain sent to the warehouse.

The synthesis of the third control loop is based on the known dependences of the power consumed by the electric Noria drive on the consumption of grain fed to the Noria.: ,,, i

In the proposed scheme, the load of the noria is monitored by the power sensor 22 of the noria consumed by the electric drive.

The regulating effect in this control loop, k, ak and in the second loop of the system, is the change in the costs of the recirculating grain and the grain entering the dryer. Obviously, in such a case, the regulating effect of each of the CTCUROES is algebraically summed.

The dual / 7 and IS dual valves, installed on the gravity of the grain to be dried and at the outlet of the recirculation shaft, have two slides, each of which is associated with its actuator, and are regulatory bodies that summarize the regulatory effects of both circuits.

When the actual load value deviates from the setpoint, the regulating device 21 causes the load to be set, changed through the actuator 23, and through the follower device 25 and the actuator 24, the positions of the corresponding gate valves of the valves 17 and 16.

Subject invention

Claims (3)

1. Method for automatic control of grain drying process in drying units, working with material recycling and equipped with temperature control systems of grain, stabilization of moisture content of dried grain by changing the ratio of costs of recycling and raw grain and stabilizing the load of the recirculation elevator, characterized in that, in order to optimize the drying processes and increase the productivity of the unit, the setting of the setpoint adjuster of the grain temperature is changed depending on the quality of gluten and the humidity of the grain to be dried. 2. The method according to claim 1, characterized in that the magnitude of the moisture removal of the grain mixture is measured in one pass through the dryer, the actual temperature of its heating and change the set point of the moisture regulator of the mixture in accordance with the measured parameters. 3. The method according to paragraphs. 1 and 2, characterized in that, in order to ensure an optimal flow of the grain mixture through the dryer, the weight flow of grain fed to the elevator is automatically stabilized. 27