JPH07109350B2 - Grain dryer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a grain dryer.

[Technology of conventional machine]

Conventionally, in the grain dryer including the ventilation drying unit 101 and the tank unit 102 (see FIG. 5), the drying chamber 1 of the ventilation drying unit 101 is used.
Grains in 03 are gradually generated by a hot air generator 104 such as a burner and dried by hot air that traverses the drying chamber 103, while being fed by a feeding device at the lower end of the drying chamber 103, for example, a rotary valve 105. The lower screw conveyor 106, the bucket elevator 107, and the upper slew conveyor 108 are fed into the tank portion 102, flow down into the drying chamber 103 again, and are subjected to the drying action by the hot air, so that they do not cause cracks in the body. The water content is gradually removed at the drying rate of 1 to finish the grain with the target moisture content.

[Problems to be solved by the invention]

When drying the grains to be dried, such as paddy rice, if the hot air temperature is kept almost constant, the drying progresses at a drying rate of about 1% per hour when the rice has a high water content of 25% or more,
When it was gradually dried to less than about 18%, the drying speed slowed down significantly (about 0.5% per hour), and this state did not change until the end of drying. In this way, if the grain is dried rapidly when it reaches a low water content, the difference in the water distribution of the bound water inside the brown rice will rapidly widen, the volume strain will increase and cracking will occur, so any high performance Even such grain dryers have to be restricted by the drying rate at this low water content.

By the way, the hot air containing moisture that has passed through the drying chamber 103 is
The air is exhausted to the outside via the air exhaust device 109 or the like, but as described above, when the grain is dried to a certain extent, the drying speed becomes slow, and naturally, the water vapor contained in the exhaust air also decreases. Regardless, it emits effective air for this drying.

The present invention has a technical problem how to reuse the exhaust air as dry air.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention provides a pair of drying chambers formed of perforated walls with a hot air chamber facing a hot air generator on one side wall, and forming a side of each drying chamber as an exhaust chamber. In the dried grain dryer, An exhaust port having a normally open valve is provided in each of the exhaust chambers, and an exhaust port having a normally closed valve is provided near the upper part of the other side wall of the hot air chamber.

B. A switching valve that can divide the hot air chamber into upper and lower parts is provided below the exhaust port of the hot air chamber.

C. Further, the exhaust chamber is provided with a humidity sensor for measuring the humidity of the exhaust air, and a moisture sensor for measuring the moisture content of the grain is provided at an arbitrary portion of the grain flow path.

D. This moisture sensor or humidity sensor operates the switching valve only when the preset value is measured to partition the hot air chamber, closes the normally open valve of each exhaust chamber, and normally closes the hot air chamber. An electric motor for operating the normally open valve, the normally closed valve, and the switching valve to open the valve is electrically connected to the humidity sensor or the moisture sensor.

I took the technical means.

[Operation] When the drying operation is started and the water content of the grain is high, the hot air generated by the hot air generator passes through the gaps between the grain particles in the drying chamber to remove moisture from the grain, resulting in high humidity. Moreover, it becomes low-temperature air and flows into the exhaust chamber, and is exhausted to the outside of the machine through the normally open valve of the exhaust chamber. In this way, the water content of the grain decreases due to the progress of drying work, and the moisture sensor detects a preset moisture content value, or the air flowing into the exhaust chamber is relatively high due to the progress of the grain drying. When the humidity becomes low and the humidity sensor detects a preset humidity value, the electric motor that operates in conjunction with the switching valve is driven to activate the switching valve to divide the hot air chamber into upper and lower parts, and above this switching valve. Open the normally closed valve provided and close the normally open valve of each exhaust chamber. As a result, the relatively high-temperature, low-humidity air that has flowed through the lower half of the drying chamber from below the switching valve of the hot air chamber into the exhaust chamber is dried again because the exhaust port of the exhaust chamber is closed. The grain is slightly dried by passing through the upper half of the chamber, and is exhausted to the outside of the machine from above the switching valve of the hot air chamber through the exhaust port.

Example of Invention

A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view of the grain dryer of the present embodiment, FIG.
FIG. 3 is a sectional view taken along the line AA in FIG. 1, and FIG.

In the grain dryer 1 composed of the box-shaped machine frame 2, a two-layer drying chamber 4 formed by a porous wall 3 is erected, and between the drying chambers 4 and 4, a hot air chamber 5 and a drying chamber 4 are provided. The outside of 4, the exhaust chamber 6,
6. Form each. Then, one side wall of the hot air chamber 5 faces the discharge side of the hot air generator 10 equipped with the burner 7, the blower fan 8 and the electric motor 9 for rotating the blower fan 8, and the other side wall has a circular shape at the upper side. An exhaust port 13 having an electric motor 12 with a servo mechanism for opening and closing the valve 11 is provided, and a rotating shaft 14 of the normally closed valve 11 and a shaft of the electric motor 12 are connected. In addition, one side wall of each of the exhaust chambers 6 and 6 faces a discharge port of a secondary hot air generator 15 equipped with a burner and a blower fan (not shown), and the other side wall has the discharge port 13 described above. Each of the exhaust ports 16 has a circular normally open valve 17 and a rotation axis of the normally open valve 17.
18 and an electric motor (with a servo mechanism) 19 connected to the rotating shaft. A switching valve 20 extending over the entire length and width of the hot air chamber 5 is provided between the both side walls of the hot air chamber 5 below the exhaust port 13 as a rotating shaft.
It is horizontally rotatably supported by 21, and the end of the rotary shaft 21 is connected to the shaft of an electric motor 22 with a servo mechanism.

At the lower end of each drying chamber 4, 4, a rotary valve 23 is installed horizontally over the entire length, and
Below the 23, a receiving plate 24 and a lower screw 25 are provided,
The supply section of the bucket elevator 26 attached to the machine frame 2 is connected to the discharge section of the lower screw 25, and the discharge section of the bucket elevator 26 is connected to the supply section of the upper screw 27. The upper screw 27 is laterally provided above the hopper parts 28, 28 formed at the upper ends of the respective drying chambers 4, 4, and the discharge part of the upper screw 27 is located in the middle of the hopper parts 28, 28. A scattering device 29 is suspended from this discharge part.

A moisture sensor 30 for measuring the moisture content of grains is attached to the machine frame 2 of one hopper section 28, and a humidity sensor 31 is attached to the machine frame 2 of one air discharge chamber 6 to measure the humidity. The sensor 31 or the moisture sensor 30 is an electric motor that operates the switching valve 20 via a signal processing device 33 provided in a control unit in the operation panel 32.
22. The motors 12 for operating the normally closed valve 11 and the motors 19, 19 for operating the normally open valves 17 are connected to drive circuits 34 to 36 (see FIG. 4). Further, an exhaust fan 37 is provided at the exhaust port 13, and the drive circuit 39 of the electric motor 38 that operates the exhaust fan 37 so that the exhaust fan 37 is driven in synchronization when the normally closed valve 11 is opened, It is connected to the humidity sensor 31 or the moisture sensor 30 via the signal processing device 33.

Next, a specific operation in this embodiment will be described.
The bucket elevator 26 is driven, and raw material grain, for example, raw rice is supplied from the supply unit of the bucket elevator 26 and is fed, and is thrown into both hopper units 28, 28 by the scattering device 29 via the upper screw 27. To do. On the other hand, while being added to the burner 7, the blower fan 8 is operated by the electric motor 9 to blow hot air into the hot air chamber 5. The hot air in the hot air chamber 5 passes through the gaps of the paddy particles from the porous walls of the drying chambers 4, 4 to reach the air exhaust chamber 6, and is exhausted to the outside of the machine from the air exhaust port 16. While flowing in from the wall surface on the hot air chamber 5 side of 4, 4 and flowing out from the wall surface on the exhaust air chamber 6 side, the hot air absorbs the water discharged from the paddy, the absolute humidity increases, and the water becomes steam. The heat of vaporization is lost and the temperature of the hot air drops. Thus, when the water content of the paddy is high, the relative humidity (hereinafter, simply referred to as humidity) of the air exhausted to the air exhaust chamber 6 increases, and the air is close to the saturated state.
It is removed to the outside of the machine from the exhaust port 16 of the exhaust chamber 6. Further, the unhulled rice discharged from the drying chamber 4 by the rotary valve 23 is re-input to the hopper unit 28 via the lower screw 25, the bucket elevator 26 and the upper screw 27,
It circulates inside the machine while passing through the drying chamber 4.

In this way, when the moisture of the paddy (mainly attached water) is discharged into the hot air and the drying progresses, only the water supply in the brown rice is reduced, and the drying speed gradually decreases. Therefore, the hot air is dried in the drying chamber 4,
Even after passing 4, the absolute humidity will increase only slightly and the heat of vaporization will not be taken away so much, so that the hot air temperature will be kept relatively. The humidity in the exhaust chamber 6 at this time is, for example, 50
%, Assuming that the moisture content of paddy is 18%, if the target finishing moisture content is 15%, the equilibrium humidity at 15% of the finished paddy is about 75% (20 ° C), so exhaust air with a humidity of 50% Consider the reusable effective dry air. That is, the target moisture content of finished paddy is 15%.
When the humidity sensor 31 detects 75% of the humidity or 75% of humidity is set in advance in the control unit, the drying speed of the grain becomes slow. For example, set 18%,
When the moisture sensor 30 detects 18%, this signal is processed by the signal processor 33 and the motor drive circuits 34, 35, 3
The electric motors 22, 12, 19, 38 are started via 6, 39, and the switching valve 20
To the horizontal position to partition the hot air chamber 5 into upper and lower
The exhaust port 13 near the top of the hot air chamber 5 is opened by rotating 11 and the exhaust fan 37 is driven, and the normally open valve 17 is rotated to close the exhaust port 16 of the exhaust chamber 6.

As a result, the hot air in the hot air chamber 5 is blocked by the switching valve 20, passes through the lower half of the drying chamber 4 and flows into the exhaust air chamber 6, and further passes through the upper half of the drying chamber 4 to pass through the hot air chamber. It flows out above the switching valve 20 of No. 5 and is removed from the machine through the exhaust port 13. That is, the paddy rice flowing down from the hopper portion 28 first passes from the exhaust air chamber 6 to the upper half of the drying chamber 4 and passes through the hot air chamber 5
Is slightly dried by the hot air flowing out above the switching valve 20 of. Since this hot air is the air that has once passed through the lower half of the drying chamber 4, the temperature is slightly lower and the humidity is also rising, and the rice in the upper half of the drying chamber 4 is slightly dried. In this way, the paddy rice flowing down to the lower half of the drying chamber 4 is
The drying action is applied by the hot air that crosses the lower half of the drying chamber 4 from below the switching valve 20 of the hot air chamber 5, and the predetermined drying action in the drying chamber 4 is performed in combination with the drying action in the upper half of the drying chamber 4.

When the exhaust fan 37 is driven together with the operation of the normally closed valve 11, the pressure loss due to passing through the drying chamber 4 twice can be covered, and the secondary hot air can be supplied simultaneously with the switching operation of the switching valve 20. By operating the generator 15, the air passing through the upper half of the drying chamber 4 is heated to reduce the humidity, and the hot air is more effective for drying. Secondary hot air generator 15
Since the air to be heated by is air having a relatively high temperature, the amount of heat required for heating may be small.

In addition, there is a case in which a temperature sensor is provided in the exhaust chamber 6 together with a humidity sensor 31 and the temperature sensor is connected to the control unit so that the equilibrium humidity that should be set to an arbitrary target finish moisture content is corrected by temperature and changed and set at any time. is there.

〔The invention's effect〕

As described above, the present invention has the following remarkable effects. That is, when the moisture content of the raw grain is high, hot air is passed through the entire drying chamber to perform normal drying operation, and the grain has been dried to a certain point preset by the humidity sensor of the exhaust air or the moisture sensor of the grain. When it is detected, the hot air chamber is divided into upper and lower parts, and a wind that passes through the lower half of the drying chamber and is effective for drying is passed through the upper half of the drying chamber again to perform drying. Therefore, the amount of heat is smaller than that of the one which is normally dried all the time, and energy is saved.

[Brief description of drawings]

FIG. 1 is a side sectional view of an embodiment of the present invention, FIG. 2 is a sectional view taken along the line AA in FIG. 1, FIG. 3 is the same plane sectional view, FIG. 4 is a control block diagram, and FIG. FIG. 1 ... Grain dryer, 2 ... Machine frame, 3 ... Perforated wall, 4 ...
Drying room, 5 ... Hot air room, 6 ... Exhaust air room, 7 ... Burner,
8 ... Blower fan, 9 ... Electric motor, 10 ... Hot air generator, 11 ... Normally closed valve, 12 ... Electric motor, 13 ... Exhaust port, 14 ...
… Rotating shaft, 15 …… Secondary hot air generator, 16 …… Exhaust port, 17
...... Normally open valve, 18 ...... Rotating shaft, 19 ...... Motor, 20 ...... Switching valve, 21 ...... Rotating shaft, 22 ...... Motor, 23 ...... Rotary valve, 24 ...... Receiving plate, 25 ... … Lower screw, 26 …… Bucket elevator, 27 …… Upper screw, 28 …… Hopper part, 29 …… Spraying device, 30 …… Moisture sensor, 31 ……
Humidity sensor, 32 …… Operation panel, 33 …… Signal processing device, 34
~ 36 ...... motor drive circuit, 37 ...... exhaust fan, 38 ...... motor, 39 ...... motor drive circuit, 101 ...... ventilation drying section, 102
…… Tank part, 103 …… Drying room, 104 …… Hot air generator,
105 …… Rotary valve, 106 …… Lower screw conveyor, 107 …… Bucket elevator, 108 …… Upper screw conveyor, 109 …… Blower.

Claims (3)

[Claims] 1. A grain dryer in which a pair of drying chambers each having a porous wall is provided by sandwiching a hot air chamber facing a hot air generator on one side wall, and the side of each drying chamber is formed as an exhaust chamber.
An exhaust port having a normally open valve is provided in each of the exhaust chambers, an exhaust port having a normally closed valve is provided near the upper side of the other side wall of the hot air chamber, and a hot air chamber is provided below the exhaust port of the hot air chamber. A switching valve that can be divided into upper and lower parts is provided, and a humidity sensor that measures the humidity of exhaust air is further provided in the air exhaust chamber, and a moisture sensor that measures the water content of the grain is provided at any location of the grain flow path. This moisture sensor or humidity sensor operates the switching valve only when the preset value is measured to partition the hot air chamber, closes the normally open valve of each exhaust chamber, and normally closes the hot air chamber. A grain dryer characterized in that an electric motor for operating the normally open valve, the normally closed valve and the switching valve to open the valve is electrically connected to the humidity sensor or the moisture sensor. 2. The grain dryer according to claim 1, wherein an exhaust fan for driving when the normally closed valve is opened is provided at the exhaust port of the hot air chamber. 3. The grain dryer according to claim 1 or 2, wherein a secondary hot air generator is exposed to the exhaust chamber.