JPH0252542B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention measures the moisture value of grains to be dried during drying over time and controls the drying loss rate so as to follow a preset target moisture value. The present invention relates to a grain drying control method that can prevent overdrying due to measurement errors in grain moisture values.

When drying grain using a heating device and blower, it is important to maintain not only the temperature and volume of the hot air applied to the grain, but also the temperature and amount of moisture released from the grain itself, to ensure quality. This can lead to a significant decrease in flavor, resulting in deterioration of taste, cracking of the shell, or inefficient drying.

Therefore, in order to appropriately and reliably control the drying of grains to be dried, the applicant has determined that the hourly drying loss rate of the grains to be dried is detected over time, and the hourly drying loss rate is kept below a preset drying rate. We have developed a method of drying grains that allows them to dry while preserving the grain, and have achieved considerable results. This grain drying method is described in Japanese Patent Application Laid-Open No. 150475/1982 and was known before the filing of this application.

However, even in the above grain drying method,
If a foreign object such as a metal piece is present in the moisture measuring device that measures the moisture value of the grain to be dried over time during drying, or if the device malfunctions, the measured moisture value may be higher than the actual moisture value of the grain to be dried. In such cases, the grain to be dried may become overdried, and its quality may be significantly impaired.

Therefore, in view of the above, the present invention aims to provide a grain drying control method that can prevent the grain to be dried from falling into an overdrying state even if an error occurs in the measured moisture value of the grain to be dried. This is the purpose.

In order to achieve the above-mentioned object, the present invention has a method in which the moisture value of grain to be dried is measured over time during drying, and the measured moisture value is converted into a daily standard moisture value based on a preset drying rate. In the case where the drying rate is controlled in accordance with the above target moisture value, the difference between the target moisture value at the entire process point, the final point, or the point just before that of the drying rate control using the target moisture value, and the measured moisture value at each point. This grain drying control method is characterized by stopping drying or issuing an alarm at the same time as drying stops when the temperature exceeds a certain value, and according to this grain drying control method, drying rate control is Even in the unlikely event that a high measurement error occurs in the measured moisture value due to the contamination of foreign objects such as metal pieces, during the entire process or at the final stage,
In such a case, immediately stop the drying process and
This has the effect of preventing the grain to be dried from falling into an over-dried state, deteriorating its quality and becoming unpalatable, and preventing the yield of dried grains from decreasing.

The grain drying control method according to the present invention will be described below with reference to the illustrated embodiments.

FIG. 1 shows the relationship between drying time and moisture content of the grain to be dried. In other words, the horizontal axis shows the drying time (hours), and the vertical axis shows the moisture value (%) of the grain to be dried.
The total drying time is divided into an initial constant-temperature drying period A, a drying loss rate control drying period B, and a final constant-temperature drying period C, depending on the temperature of the hot air applied to the grains to be dried. The straight line D in the drying rate controlled drying period B indicates the target moisture value based on the preset drying rate, and this target moisture value is based on the moisture content at the start and end of the drying rate controlled drying period B. Depending on the relationship between the moisture value of the dried grains and the time of the drying period B for controlling the drying loss rate, the hourly drying loss rate is set in advance to, for example, 1.0% or 0.8%. In addition, the black dots in the figure indicate the hourly target moisture value, and the white dots indicate the measured moisture value of the grain to be dried.

Now, when drying the grains, in the initial constant temperature drying period A, the temperature of the hot air is kept constant and the grains to be dried are ventilated and dried. Then, at the end of the initial constant temperature drying period A, that is, at the start of the drying rate controlled drying period B, the moisture value of the grain to be dried is measured, for example, three times, and the average value is used as the drying rate controlled drying period. The initial moisture value of B is determined, and the drying rate is determined in relation to the final target moisture value of the drying period B, and the target moisture value D is set. In the drying period B with drying rate control,
For example, measuring the moisture value of dried grain every hour,
The hot air temperature or hot air volume is controlled so that the hourly measured moisture value is in line with the target moisture value D, and drying is continued. At the end of drying loss rate control drying period B, the target moisture value D is a moisture value slightly higher than the finished drying moisture value,
For example, if the finished drying moisture value is 14%, it is set to 15%, but when reaching the end of the drying period B, the moisture content of the grain to be dried is measured three times and the average value is set to 15%. Detect values. Then, based on the average moisture value, the entire drying process is completed through a finishing constant temperature drying period C for a required time.

By the way, if a measurement error occurs in which the measured moisture value of the grain to be dried appears higher than the actual moisture value during the entire process or the final stage of the drying rate controlled drying period B, the final constant temperature drying will be excessive, so if it continues as it is, The grain to be dried becomes over-dried, but if the moisture value measured every hour during the entire process of drying rate control drying period B or the moisture value measured at the end of the drying period exceeds a certain value, combustion in the hot air generator is stopped. Since drying is immediately stopped by stopping the blowing of hot air or by stopping the blowing of hot air, it is possible to prevent the grain to be dried from becoming over-dried. The measured moisture value at which drying is to be stopped is set in advance to, for example, about 2 to 3% from the hourly target moisture value in all steps of the drying rate control drying period B and the target moisture value at the final stage. Note that an alarm may be issued at the same time as the drying is stopped.

FIG. 2 illustrates an apparatus for carrying out the method of the invention.

That is, 1 is a moisture measuring device that measures the moisture of the grain to be dried over time, 2 is a target moisture value setting device that sets a target moisture value every hour, 3 is a comparison circuit, and 4
Reference numeral 5 indicates a combustion or blowing control circuit for a hot air generator, and 5 indicates the hot air generator. A control signal is sent to the air blowing control circuit 4, and the combustion or air blowing control circuit 4 controls the temperature or amount of hot air blown from the hot air generator 5 so that the measured moisture value is in line with the target moisture value.

On the other hand, 6 is another comparison circuit, and 7 is a measured moisture value upper limit setter. A control signal is sent when the measured moisture value in the rate control drying period B exceeds the target moisture value D at the time of measurement by a certain value set in the measured moisture value upper limit setter 7. 8
9 is a combustion or air blowing stop circuit, and 9 is an alarm circuit that receives a control signal sent from the comparator circuit 6, and when the measured moisture value appears higher than the target moisture value at the measurement point by more than a certain value, the hot air is stopped. Generator 5
This constitutes a circuit that immediately stops drying by stopping combustion or air blowing.

According to the apparatus configured as described above, the moisture value of the grain to be dried is measured over time by the moisture measuring device 1 during the drying period B under drying rate control, and the moisture value is set in advance by the target moisture value setting device 2. The drying rate control device is operated in accordance with the target moisture value D. From the beginning to the end of the drying period B with controlled drying rate, the moisture content of the grain to be dried is measured over time, but in the unlikely event that
If a foreign object such as a metal piece is present in the moisture measuring device 1, or if the measured moisture value appears abnormally high due to a malfunction, a control signal is sent from the comparison circuit 6, and the control signal is sent to the hot air generator 5. Since the combustion or air blowing is stopped and the drying is immediately stopped, it is possible to prevent the grain to be dried from becoming overdried. Furthermore, if an alarm is issued at the same time, an abnormal state can be reliably detected, and the abnormal state can be resolved and necessary recovery operations can be performed without delay.

[Brief explanation of drawings]

The drawings show an embodiment of the grain drying control method according to the present invention, and FIG. 1 is a diagram showing the relationship between the drying time and the moisture value of the grain to be dried to explain the method, and FIG. 1 is a block diagram of an apparatus implementing the method of the invention; FIG. A...Initial constant temperature drying period, B...Drying loss rate control drying period, C...Final constant temperature drying period, D...Target moisture value based on preset drying rate, 1...Moisture measuring device,
2...Target moisture value setting device, 3...Comparison circuit, 4...
... Combustion or blowing control circuit of hot air generator, 5...
... Hot air generator, 6 ... Comparison circuit, 7 ... Measured moisture value upper limit setting device, 8 ... Combustion or blowing stop circuit, 9 ... Alarm circuit.

Claims (1)

[Claims] 1. In a device that measures the moisture value of the grain to be dried during drying over time and controls the drying rate so that the measured moisture value follows a target moisture value based on a preset drying rate, the target moisture value is If the difference between the target moisture value at all process points, the final point, or the point immediately before the drying loss rate control based on value, and the measured moisture value at each point is greater than a certain value, drying is stopped, or drying is stopped. A grain drying control method characterized by simultaneously issuing an alarm.