JPH0544593B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to drying of a circulating grain dryer that circulates grain between a storage section and a drying section and supplies hot air to the grain in the drying section to dry the grain. Regarding control method.

[Conventional technology]

A circulating grain dryer circulates grain loaded in a storage section between the storage section and a drying section, and supplies hot air to the grain in the drying section. Further, the temperature of the hot air is determined based on the type of grain, the amount of grain to be loaded, the outside temperature, etc., and is controlled to maintain the determined temperature from the start of drying to the end of drying. The grains loaded in the dryer are heated by hot air while being circulated between the storage section and the drying section, raising the temperature of the grains and drying them.

[Problem to be solved by the invention]

However, since the temperature of the grain is low at the beginning of drying, as shown in Figure 4, after the grain dryer supplies hot air and starts drying, the temperature of the grain rises and moisture evaporates from the grain. It takes time for drying to actually start, resulting in longer drying times.
There was a problem.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a drying control method for a circulating grain dryer that can accelerate the rise in grain temperature and shorten drying time.

[Means to solve the problem]

In the present invention, the grain is circulated between the storage section and the drying section, and the temperature of the hot air supplied to the grain in the drying section is set to a target value Ta calculated based on the outside temperature To and the grain loading amount W. In a drying control method for a circulating grain dryer that controls and dries grain, the time required for grain to circulate once between a storage section and a drying section is calculated based on a grain loading amount W and a grain circulation speed V, The method is characterized in that the temperature of the hot air is controlled to be higher than the target value Ta during the period from the start of drying until the time elapses, regardless of the moisture content of the grain.

[Effect]

In the present invention, the time required for the grain to circulate once between the storage section and the drying section is calculated based on the grain loading amount and the grain circulation speed, and from the start of drying to the elapse of the above period, the grain The temperature of the hot air is set to be higher than the target value Ta regardless of the moisture content.
Therefore, even if the initial moisture content of the grain to be dried is high and far apart from the target moisture content, or if the initial moisture content is low and close to the target moisture content, the grain temperature rises quickly and the drying time of the grain increases. Can be shortened.

Note that until the grain goes through one cycle, it is in the stage of heating the grain, and since the temperature of the grain is low, there is no negative effect on the quality of the grain, and after the second cycle when the temperature of the grain rises, hot air is heated. Since the temperature is set to a target value Ta that is lower than that of the first cycle, grain cracking and the like will not occur and the quality will not deteriorate. Also,
Since the time required for one cycle of grain to be circulated is calculated based on the loading amount and the circulation speed, the time required for one cycle to be circulated can be determined accurately.

〔Example〕

Embodiments of the present invention will be described according to the drawings.

FIG. 1 shows an example of a circulating grain dryer, which has an upper storage section 10 and a lower drying section 12. The drying section 12 is provided with a flow path 14 partitioned by a net-like wall surface, through which the grains from the storage section 10 flow down. Hot air chambers 16 and exhaust air chambers 18 are alternately formed between adjacent flow passages 14. Hot air is sent to the hot air chamber 16 by a burner and a suction fan (not shown).
The air flows through the flow path 14 to the exhaust chamber 18 side. As a result, the grains in the flow path 14 are dried. A rotary valve 20 is provided at the lower opening of the flow path 14 to allow dried grains to fall into a lower hopper 22. A screw conveyor 24 is provided at the bottom of the lower hopper 22 and is adapted to supply grain to the lower part of a bucket conveyor 26. This grain is lifted above the storage section 10 by a bucket conveyor 26 and dropped onto a rotary equalizer 28. The grains in the rotary equalizer 28 fall into the storage section 10 under the influence of centrifugal force, and the upper surface of the deposited grains has a mortar shape.

A temperature sensor 30 is disposed within the hot air chamber 16 and is adapted to detect the hot air temperature _T1 .
Further, a temperature sensor 32 is disposed outside the dryer main body to detect the outside air temperature T ₀ .
Detection signals from the temperature sensors 30 and 32 are supplied to a microcomputer 38 via a multiplexer 34 and an A/D converter 36. The amount W of grain loaded into the dryer is set by a loading amount setting device 40, and a predetermined signal thereof is supplied to the microcomputer 38. The microcomputer 38 supplies a generated heat amount adjustment signal to the generated heat amount adjustment circuit 44 in response to input signals from the temperature sensors 30 and 32 and the filling amount setting device 40. The generated heat amount adjustment circuit 44 is adapted to adjust the flow rate of kerosene to a burner (not shown) and the amount of air mixed with this kerosene.

Next, the software configuration of the microcomputer 38 will be explained according to the flowchart shown in FIG.

At step 100, the outside temperature To and the grain loading amount W are read. Next, in step 102, the hot air temperature target Ta is determined as follows.

Ta←aTo+bW+c …(1) K←fW+g …(2) Ta←Ta+K …(3) Here, K is the increment of hot air temperature that is higher in the first cycle than in the second and subsequent cycles, as shown in Figure 3. For example, 5°C can be adopted. Further, a to c, f, and g are positive constants.

Then, in step 104, the grain circulation speed V
and one cycle are determined as follows. Circulation speed V
is the amount of grain dropped from the rotary valve 20 per unit time, and one circulation time is the time it takes for the entire amount of grain to circulate through the storage section 10 and the drying section 12 once.

V←1/(h-mW) …(4) 5←W/V…(5) Here, h and m are positive constants.

Next, proceed to step 106, read the hot air temperature _T1 , and proceed to step 108, where this _T1 is set as the target value.
The amount of heat generated is controlled by controlling the amount of fuel and air supplied to the burner so that Ta is achieved. Next, in step 110, it is determined whether one cycle time t has elapsed, and the steps 106 and 106 are performed during one cycle time t.
Repeat the process in step 108. Through the above treatment, hot air having a temperature higher than normal by K is supplied regardless of the initial moisture content of the grain, and the temperature of the grain is increased in a short time.

When it is determined in step 110 that one cycle time t has elapsed, the process proceeds to step 111, where the target value Ta is decreased by a predetermined value K. Next, the process proceeds to step 112, where the hot air temperature _T1 is read, and in step 114, the amount of heat generated by the burner is controlled so that the hot air temperature _T1 becomes the target value Ta. Next, if it is determined in step 116 that the drying is not completed, the steps 112 and 112 described above are performed.
Repeat process 114. The completion of drying is determined by automatically measuring the moisture content of the grain using a moisture meter, for example, and checking whether the moisture content reaches a set moisture content. If it is determined in step 116 that the drying is complete, the process proceeds to step 118, where the supply of kerosene to the burner is cut off and the above process is completed.

In this way, the hot air temperature in the hot air chamber 16 and the average temperature of the grains change as shown in FIG. In other words, for the first cycle, the hot air temperature is set high by K alone regardless of the moisture content of the grain, so even if the initial moisture content of the grain is high and far apart from the set moisture content, the initial moisture content Even when the moisture content is low and close to the set moisture content, the average grain temperature rises faster than in the conventional example shown in FIG. Since the temperature of the grain is low during the first cycle, the average grain temperature will not become too high and the quality of the grain will not deteriorate.

Note that the value of the increment K of the initial hot air temperature only needs to be a positive value, and does not need to depend on the amount W of grain filling.
Alternatively, it may be a value that decreases over time. formula
(1) and (4) are examples, and it goes without saying that the present invention is not limited thereto.

〔Effect of the invention〕

In the drying control method for a circulating grain dryer according to the present invention, one circulation time of grain is calculated based on the grain loading amount W and the grain circulation speed V, and one circulation time elapses after starting drying. Until then, the hot air temperature was controlled to be higher than the target value Ta during normal drying, regardless of the moisture content of the grain, so the grain temperature could be maintained without deteriorating the quality of the grain. It has the excellent effect of speeding up the drying time of grains and shortening the drying time of grains.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a circulating grain dryer according to an embodiment of the present invention, Fig. 2 is a control flow chart, and Fig. 3 is a control flow chart.
The figure is a diagram used to explain the operation of this embodiment, and FIG. 4 is a diagram used to explain the operation of the conventional example. 10... Storage section, 12... Drying section, 14... Downflow path, 16... Hot air chamber, 18... Exhaust chamber, 20...
...Rotary valve, 24...Screw conveyor, 26...Bucket conveyor, 28...Rotary equalizer 28, 30, 32...Temperature sensor, 40...
...Filling amount setting device.

Claims (1)

[Claims] 1. The grain is circulated between the storage section and the drying section, and the temperature of the hot air supplied to the grain in the drying section is controlled to be the target value Ta calculated based on the outside temperature To and the grain loading amount W. , in a drying control method for a circulating grain dryer for drying grain,
Calculate the time it takes for grain to circulate once between the storage section and the drying section based on the grain loading amount W and the grain circulation speed V,
The circulation is characterized in that the temperature of the hot air is controlled to be higher than the target value Ta, regardless of the moisture content of the grain, from the start of drying until the time elapses. Drying control method for grain dryers.