JPH01167569A - Drying control method for cereal - Google Patents

Abstract

PURPOSE:To prevent the cracking of a grain and deterioration of taste, by a method wherein a sudden temperature change is not exerted on cereals under drying by the passage of blast and besides the temperature of blast is controlled in a preset range and at a value lower than a preset upper limit temperature. CONSTITUTION:The moisture content of cereals under drying is automatically measured, in order, at intervals of a time, set by a schedule timer 19, by means of a moisture content measuring circuit 12. Based on the measured moisture content, an estimated moisture content value and an assumed dry factor are calculated by a statistical processing circuit 13. An error being a function of a target dry reduction factor and an assumed dry reduction factor is calculated by an error calculating circuit 14. Further, after a correction error is calculated by a PID calculating circuit 15, the control temperature of blast is calculated by a control temperature calculating circuit 16. An error between the control temperature and a temperature measurement value is corrected, and the correction value forms a control amount of a pump drive circuit 10, and the temperature of blast is controlled in a control width preset by a temperature control width limiter 23 and at a value lower than the upper limit of temperature set by a temperature upper limit setter 24 in a direction in which the error is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a grain drying control method for drying grain by blowing hot air while maintaining a predetermined drying loss rate.

Conventional technology Conventionally, as a grain drying control method for drying grains by ventilation of hot air while maintaining a predetermined drying loss rate,
As described in Publication No. 09, there is a known method that measures the moisture content and grain temperature of grains and controls the temperature of hot air so that the grains being dried are dried at a preset drying loss rate. There is.

Problems to be Solved by the Invention Incidentally, in the conventionally known grain drying control method, the drying loss rate of the grain during drying is measured at predetermined intervals (for example, 1 hour), and Since the temperature of the hot air is changed so that it approaches the target drying rate at the time of measurement, the temperature of the hot air often changes rapidly at each measurement time, which can cause cracking of the grain and deterioration of taste. It has become.

In view of the problems with the conventional grain drying method, the present invention has been developed to prevent sudden temperature changes from being caused to grains during drying due to hot air ventilation, and to maintain the temperature of the hot air within a preset range. It is also an object of the present invention to provide a grain drying control method that can properly dry grains by controlling the drying loss rate without causing shell cracking or deterioration of taste by controlling the temperature below a preset upper limit temperature. It is something to do.

Means for Solving the Problems The present invention has the following technical means for achieving the object.

In other words, its structure measures the moisture content of grains during ventilation drying with hot air at predetermined time intervals, and sequentially performs statistical processing on each measured moisture value to calculate the estimated drying loss rate or estimated moisture value at each measurement point. Calculate the estimated drying loss rate for the target drying rate or target moisture value at each preset measurement time point Manoko uses the error in the estimated moisture value as the control amount, and calculates the estimated drying rate within the preset temperature control range and This grain drying control device is characterized in that the temperature of the hot air is controlled to be below a preset upper temperature limit and to reduce the error.

Function The moisture content of drying grains is gradually reduced over time as the hot air removes moisture from the grains, but the moisture content of drying grains is measured at predetermined intervals (for example, 1 hour). . These measured moisture values are sequentially statistically processed, and all past measured moisture values are used as data to calculate the estimated drying rate at each measurement point. This estimated drying rate is a value very close to the target drying rate at each preset measurement point, and the error of the estimated drying rate with respect to the target drying rate is the control amount, and is within the preset temperature control range. The temperature of the hot air is controlled in such a way that the error is reduced to below a preset upper temperature limit. therefore,
The temperature change of the hot air is gradual, and the grains being dried are not subjected to sudden temperature changes, and the temperature does not exceed the upper limit of the appropriate temperature, so cracking of the grains and deterioration of taste do not occur.

Example Embodiments of the present invention will be described with reference to the drawings.

1 and 2 each show an example of an apparatus for carrying out the method according to the invention.

In FIG. 1, the main parts of this device are composed of a temperature control block 1 and a drying control block 2, which are also equipped with a temperature sensor 3, a moisture sensor 4, a drying rate setting device 5, and a temperature setting device 6. ing.

The temperature control block 1 includes a temperature measurement circuit 7, an error calculation circuit 8, a PID calculation circuit 9, and a pump drive circuit IO.
The temperature sensor 3 is connected to a temperature measurement circuit 7. 11 is a fuel pump, and this fuel pump 11 supplies fuel to the hot air generator,
The amount of fuel supplied is controlled by the pump drive circuit IO. The drying rate control block 2 also includes a moisture measurement circuit 12, a statistical processing circuit 13, an error calculation circuit 14, a PID calculation circuit 15, a control temperature calculation circuit 16,
Hourly drying rate setting circuit 17, temperature setting circuit! 8 and a schedule timer 19, the hourly drying rate setting circuit 17 includes a drying rate setting device 5, and the temperature setting circuit 1
8 is connected to a temperature setting device 6, respectively. The schedule timer 19 is for automatically performing moisture measurement and statistical processing every hour.

In the embodiment shown in FIG. 2, a target moisture calculation circuit 20 is further added to the drying rate control block 2 in the embodiment shown in FIG.

In addition, 1. In the device configured as above, the PID
A temperature control width limiting circuit 21 is interposed between the calculation circuit 15 and the control temperature calculation circuit 16, and a temperature upper limit setting circuit 22 is interposed between the control temperature calculation circuit 16 and the error calculation circuit 8. 21 is a temperature control width setting device 23
Alternatively, each of the temperature upper limit setting circuits 22 is provided with a temperature upper limit setting device 24 . The temperature control width limiting circuit 2] sets the allowable range of temperature change depending on the type of grain to be dried, drying conditions, etc., and the temperature upper limit setting circuit 21 sets the upper limit of the allowable temperature. It is.

In the apparatus configured as described above, the temperature of the dry hot air is detected by the temperature sensor 3, and the moisture of the grain is detected by the moisture sensor 4.
Detected in

When drying grain, first, the hourly drying rate (moisture loss value per hour) of the grain is set to, for example, 1% by operating the drying rate setting device 5, and then the set target drying rate T is set.
The reference hot air temperature TC corresponding to the temperature is set to, for example, 52° C. by operating the temperature setting device 6. Furthermore, taking into consideration the type of grain to be dried, drying conditions, etc., the temperature control width setting device 23 presets the permissible temperature change range for the grain without causing shell cracking or deterioration of taste. The upper limit value is set in advance by the temperature upper limit setter 24.

Then, the moisture measuring circuit 12 is activated to measure the moisture value of the grain immediately before the start of drying as the initial moisture value, and then drying is started.

By the way, if the estimated moisture value of the grain is y and the measured moisture value is M, the estimated moisture value y is a function f (M, T) of the measured moisture value M and the target drying rate T, and usually y = ax + b (where a is the estimated drying loss rate and X is the drying time.)
.

The moisture content of the grain being dried is automatically measured sequentially in the moisture measuring circuit 12 at intervals set by the schedule timer 19, and based on the measured moisture results, the statistical processing circuit 13 calculates the estimated moisture value y and the estimated drying temperature. A reduction rate a is calculated.

This statistical processing is an arithmetic processing for estimating the true value of the measurement, such as the method of least squares. Then, in the error calculation circuit 14, an error 2 which is a function of the target drying rate T and the estimated drying rate a is calculated [Z-4(T, a)]
, Sara 1. :l'ID calculation circuit 15 calculates a correction error of 2° [Z'-f(Z)], and control temperature calculation circuit 16 calculates hot air control temperature TC'(TC' =
TC+ Z'・K where K is the temperature control rate).

The signal of the hot air control temperature TC' is the temperature control block l
is input to the error calculation circuit 8, and the error ZT between the temperature measurement value TM sent out from the temperature measurement circuit 7 is calculated (ZT=
TC-TM), the correction error ZT is further corrected by the PID calculation circuit 9.
' is calculated, [ZT'-f(Z, T)], and its correction error ZT'' becomes the control amount of the pump drive circuit 10,
The pump drive circuit 10 controls the fuel supply amount of the fuel pump 11 in a direction that minimizes the hot air temperature correction error ZT'. This control is carried out within the temperature control range preset by the temperature control range limiter 23 and by the temperature upper limit setter 24.
The temperature of the hot air is controlled below the upper limit of the temperature set in advance, and the temperature of the hot air is controlled in a direction that reduces the correction error ZT' as described above. In the apparatus shown in FIG. 2, a target moisture value Y is calculated every hour in a target moisture calculation circuit 20, and an error calculation circuit 14 calculates an error 2 between the target drying rate T and the estimated drying rate a. Function f (y, Y) of value Y and estimated moisture value y
It is calculated as That is, the initial moisture value b measured by the moisture measurement circuit 12, the target drying rate T1, the moisture measurement time TI
Therefore, the target moisture value Y is Y=b-T-TI. Note that the other operations are similar to those of the device shown in FIG.

Therefore, the temperature of the dry hot air is controlled using the error determined from the target drying rate T and the estimated drying rate a based on all statistically processed past data. Since the temperature control is performed within the preset temperature control range and temperature upper limit, the control amount at each moisture measurement point is small, and does not exceed the preset range and upper limit, so that the temperature change due to hot air temperature control is The drying process is gradual, and the drying grains are not subject to sudden temperature changes.
Automatic drying of grains can be safely performed without causing shell cracking or deterioration of taste depending on the type of grains, drying conditions, etc.

Effects of the Invention As described above, the present invention measures the moisture content of grains during ventilation drying with hot air at predetermined time intervals, and sequentially performs statistical processing on each measured moisture value to calculate the estimated drying loss at each measurement point. The error of the estimated drying rate or estimated moisture value with respect to the target drying rate or target moisture value at each preset measurement point is used as the control amount, and the preset temperature control width is calculated. This method controls the temperature of the hot air in such a way as to reduce the error by keeping it within the temperature limit and below the preset temperature limit, so that the hot air does not cause sudden temperature changes to the grains being dried. In addition, the temperature of the hot air is controlled within a preset range and below the upper limit temperature, which prevents cracking of the grains and deterioration of flavor, and allows grains to be properly dried by controlling the drying loss rate. Achieve the desired effect.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of an apparatus for carrying out the method according to the present invention, and FIG. 2 is a block diagram showing the other side.

Claims (1)

[Claims] The moisture content of grains during ventilation drying with hot air is measured at predetermined time intervals, and each measured moisture value is sequentially subjected to statistical processing to calculate the estimated drying loss rate or estimated moisture value at each measurement point. The error of the estimated drying loss rate or estimated moisture value with respect to the target drying rate or target moisture value at each measurement point is taken as the control amount, and within the preset temperature control range and below the preset temperature upper limit. , a grain drying control method characterized by controlling the temperature of hot air in a direction that reduces the error.