JP5884673B2 - Grain dryer - Google Patents

Description

  The present invention relates to a grain dryer provided with exhaust air return means.

  Patent Document 1 discloses a grain dryer provided with exhaust air return means that uses a part of exhaust air discharged from an exhaust fan mixed with hot air generated by a combustion burner. Patent Document 2 discloses a grain dryer that can arbitrarily change the rotational speed of the exhaust fan.

JP 2010-271020 A JP 2011-163603 A

In the grain dryer equipped with the exhaust air return means that uses a part of the exhaust air, when the amount of grain to be stretched is small, the hot air blows to the exhaust fan side and the hot air does not act properly on the grain, It was difficult to adjust the grain temperature appropriately. Therefore, it is a problem to be solved by the invention to provide a grain dryer capable of appropriately adjusting the grain temperature.

The present invention has taken the following technical means to solve the above problems.
That is, the invention described in claim 1 is a wind return unit for returning the exhaust air discharged from the exhaust fan (6) to the hot air chamber (11) side, and an outflow exhaust air and hot air chamber (11) discharged outside the apparatus. ), And a rotation speed adjusting means for changing the rotational speed of the exhaust fan (6). The control device (17) is provided during the drying operation. ,
The ratio of the return exhaust air is adjusted by the exhaust air adjusting means, and the rotational speed of the exhaust fan (6) is adjusted by the rotational speed adjusting means, and moisture spots that are the moisture distribution state of each grain layer are detected. When the control device (17) determines that the moisture spots are larger than a predetermined value by the detecting means, the grain dryer is configured to reduce the rotational speed of the exhaust fan (6) .

The invention according to claim 2 is characterized in that when the control device (17) determines that the amount of tension is equal to or less than a set amount, the rotational speed of the exhaust fan (6) is reduced. Item 2. A grain dryer according to Item 1.

According to the third aspect of the present invention, the exhaust air returning means for returning the exhaust air exhausted from the exhaust air fan (6) to the hot air chamber (11), the outflow exhaust air and the hot air chamber (11) exhausted outside the apparatus. ) Change the rotation speed of the exhaust fan (6), the exhaust air adjusting means for adjusting the ratio of the return exhaust air returned to the side), the means for selecting the increase / decrease of the return exhaust air ratio by the exhaust air adjusting means, And a control device (17) adjusts the rate of the return exhaust air by the exhaust air adjusting means during the drying operation, and the exhaust fan (6) by the rotational speed adjusting means. The grain dryer characterized by adjusting the number of rotations and decreasing the number of rotations of the exhaust fan (6) when the control device (17) determines that the amount of tension is equal to or less than a set amount.

The invention according to claim 4 is the grain dryer according to claim 2, further comprising means for selecting increase / decrease of the ratio of the return exhaust air by the exhaust air adjusting means.

According to the first aspect of the present invention, the rotational speed adjusting means for changing the rotational speed of the exhaust fan (6) is provided, and the control device (17) during the drying operation causes the ratio of the return exhaust air by the exhaust air adjusting means. By adjusting the rotational speed of the exhaust fan (6) by the rotational speed adjusting means, the grain temperature can be easily adjusted and drying in various drying forms can be performed. In addition, when the control device (17) determines that the moisture spots are larger than a predetermined value, the air volume from the exhaust fan (6) is reduced by decreasing the rotational speed of the exhaust fan (6), and the grain temperature is reduced. Raise. Thus, moisture transfer between grains in different moisture layers can be made smooth, and moisture spots for each grain layer can be reduced.

According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, when the control device (17) determines that the amount of tension is equal to or less than the set amount, the rotation of the exhaust fan (6) By reducing the number, it is possible to reduce hot air blow-through and perform stable drying. Moreover, grain temperature can be raised, reducing the production amount of the hot air by a combustion burner (5).

According to the third aspect of the present invention, the rotational speed adjusting means for changing the rotational speed of the exhaust fan (6) is provided, and the control device (17) during the drying operation causes the ratio of the return exhaust air by the exhaust air adjusting means. By adjusting the rotation speed of the exhaust fan (6) with the rotation speed adjusting means, the grain temperature can be easily adjusted, and drying in various drying forms can be performed. When the device (17) determines that the amount of tension is equal to or less than the set amount, the number of rotations of the exhaust fan (6) is decreased, thereby reducing hot air blow-through and stable drying. Moreover, grain temperature can be raised, reducing the production amount of the hot air by a combustion burner (5). Further, by having a means for selecting increase / decrease of the rate of return exhaust air by the exhaust air adjusting means, if the exhaust air rate is increased by the exhaust air adjusting means, the exhaust heat can be used correspondingly, so that energy is saved. Decreasing the wind ratio increases the grain temperature, so the drying speed can be improved. And these can be suitably performed by a user's selection.

According to the fourth aspect of the present invention, in addition to the effect of the second aspect of the invention, by means of selecting the increase / decrease of the ratio of the return exhaust air by the exhaust air adjusting means, the exhaust air adjusting means exhausts the exhaust air. Increasing the wind ratio can save energy because the exhaust heat can be used accordingly, and decreasing the exhaust ratio increases the grain temperature, thereby improving the drying rate. And these can be suitably performed by a user's selection.

It is a perspective view of the internal structure of the whole grain dryer concerning embodiment of this invention. It is an internal perspective view of the structure of the drying part and grain collection part of the grain dryer of FIG. It is a block diagram of the drying part and the grain collection part including the external structure of the grain dryer of FIG. It is a principal part back perspective view of the exhaust wind discharge part of the grain dryer of FIG. It is a principal part longitudinal cross-sectional view of the exhaust wind discharge part of the grain dryer of FIG. It is a top view showing the ventilation streamline of the drying part of the grain dryer of FIG. It is a system block diagram of the grain dryer of FIG. It is a figure which shows the example of a division of a moisture spot layer. It is a 1st control flowchart of the grain dryer of FIG. It is a front view of the operation panel of the control box of the grain dryer of FIG.

Embodiments specifically configured based on the above technical idea will be described below with reference to the drawings.
FIG. 1 is a perspective view of the internal structure of the entire grain dryer 1 according to the embodiment of the present invention. FIG. 1 shows a state in which the upper part from the storage unit 2 is separated and lifted from the drying unit 3, and the longitudinal direction of the main body is the front-rear direction and the short direction is the left-right direction. FIG. 2 is an internal perspective view of the configuration of the drying unit 3 and the grain collecting unit 4 of the grain dryer 1, and FIG. 3 is a configuration diagram of the drying unit 3 and the grain collecting unit 4 including the external configuration. Show.

  The grain dryer 1 is formed with a storage unit 2, a drying unit 3, and a cereal collecting unit 4 in that order from above, and a combustion burner while circulating the grains by driving a groining machine 7 provided on the outer periphery thereof. 5 is a so-called circulation type grain dryer that dries the hot air generated by the combustion of No. 5 and the exhaust fan 6 on the grain in the drying unit 3. The grain outlet of the drying unit 3 is provided with a rotary valve 14 that allows a predetermined amount of grain to flow down while rotating in the forward and reverse directions, and the delivered grain is received by the lower spiral 15 of the grain collecting unit 4 that leads to the groining machine 7. By supplying the spreader (not shown) of the storage unit 2 with the upper transport device 8 connected to the upper side of the groining machine 7, the embedded grains are uniformly accumulated and stored on the entire surface of the storage chamber 2.

  A burner case 40 having a large number of slit-like outside air intake ports 50 formed on the front side is attached to the front side of the main body and at the center of the left and right sides of the drying unit 3, and the combustion burner 5 is accommodated in the burner case 40. The combustion disc surface of the combustion burner 5 is placed so as to face the main body. In addition, an exhaust fan 6 is provided at the center of the left and right of the drying unit 3 on the rear side of the main body.

  In the position adjacent to the burner case 40 on the front side of the main body, a grain raising machine 7 is provided for raising the grain, and the upper part of the main body is provided with a transfer spiral and stores the grain raised by the grain raising machine 7. 2 and a dust suction fan 9 for sucking and removing foreign matters such as scum mixed in the grains being conveyed by the upper conveyance device 8. In addition, a moisture meter 10 for detecting the moisture of the grain is attached to the groining machine 7, and the moisture value is calculated by taking the sample grain out of the grains that are being pulverized and detecting the electrical resistance value for each single grain every set time. .

  In the drying section 3, left and right grain flow passages 13, 13 are installed between the front plate 3a and the back plate 3b of the fuselage, and hot air on the left and right outer sides is sandwiched between the respective grain flow passages 13, 13. The chambers 11 and 11 and the central exhaust chamber 12 are formed. Dry hot air generated by the combustion burner 5 passes through the hot air chamber 11, and the exhaust air chamber 12 communicates with the exhaust air fan 6 at the left and right central portions. A rotary valve 14 that feeds the grain to the cereal collecting unit 4 is provided at the lower end of the grain lowering passage 13, and the grains in the storage unit 2 sequentially pass through the rotation of the rotary valve 14.

  4 is a rear perspective view of the main part of the exhaust air discharge unit of the grain dryer 1 according to the embodiment of the present invention, FIG. 5 is a longitudinal sectional view of the main part of the exhaust air discharge unit, and FIG. The top view showing the ventilation streamline of 3 is shown.

  The exhaust air discharge unit is provided with an exhaust air duct 20 projecting from the back plate 3b to the outside of the box, and the exhaust air supply duct 21 is connected to the upper part of the exhaust air duct 20 and communicated forward from the exhaust air duct 20. A fan body 6a is extended from the back plate 3b to the inside of the box toward the inside of the box, and a fixed plate 6c and fan blades 6b are attached so that the tip of the exhaust fan 6 extends into the exhaust chamber 12. Configure. In addition, a fan motor 6d is disposed on the upper portion of the fan body 6a, and a transmission belt 6e is provided on the back side to drive the fan blade 6b.

  Since the fan motor 6d is installed in the exhaust chamber 12 integrally with the exhaust fan 6, a simple fan drive unit by the external fan motor 6d is configured without causing exhaust air leakage to the outside air. Can do. Further, the fan motor 6d is configured such that the rotational speed can be adjusted by a fan inverter 73 described later, which is a rotational speed adjusting means.

  The exhaust fan 6 includes an axial flow type fan blade 6b and a fixed plate 6c that applies pressure to the exhaust air generated by the fan blade 6b inside the circular fan body 6a. A discharge duct 20 having a circular cross section is connected to the discharge side. Thus, the grain dryer 1 concerning this invention is equipped with the structure which circulates a part of exhaust air from the discharge fan 6, and uses again for grain drying.

  The configuration for circulating the exhaust air will be described. The exhaust from the exhaust fan 6 is divided into an outflow exhaust that is discharged outside the machine and a return exhaust that circulates to the hot air chamber side. In the exhaust duct 20, the outflow exhaust and the return exhaust are separated. A first control valve 23 serving as an exhaust air adjusting means for adjusting the ratio is provided, and a second exhaust air outlet is provided at the exhaust air inlet of the exhaust air supply duct 21 to adjust the amount of return exhaust air supplied into the exhaust air supply duct 21. A control valve 22 is provided. The first control valve 23 and the second control valve 22 are configured to be rotated by a horizontal axis 23a and a rotation axis 22a, respectively, and the first control valve drive motor 25 is connected to the rotation axis 23a. The second control valve drive motor 26 is also connected to the rotating shaft 22a. The amount of return exhaust air flowing from the exhaust air supply duct 21 into the return duct 27 is appropriately adjusted by the control device 17.

  The exhaust air supply duct 21 is provided from the upper part of the exhaust air fan 6 to the left and right sides, and distributes the return exhaust air to the left and right sides. The return duct 27 that constitutes the exhaust air return means is a cylindrical passage provided in the left and right hot air chambers 11 along the front-rear direction. In the present embodiment, the return duct 27 is formed in a circular shape and is discharged from the exhaust air fan 6. Return part of the exhausted air to the hot air chamber 11 side.

  A heat exhaust air passage case 43 is provided between the main body and the burner case 40. Then, one end of the return duct 27 and the hot exhaust air passage case 43 are connected to each other, and the return exhaust air returned from the return duct 27 is mixed with the hot air generated by the combustion burner 5 in the hot exhaust air passage case 43. .

  Next, the hot air generated by the combustion burner 5 receives the suction action of the exhaust fan 6 and acts as dry hot air on the grains in the downstream passage 13 from the hot air chamber 11, and then partially returns to the return duct 27. Then, a process until it mixes with a hot air in the hot exhaust wind passage case 43 and is supplied to the hot air chamber 11 is demonstrated.

  Hot air generated by the combustion burner 5 is supplied from the burner case 40 to the hot air chamber 11. The hot air in the hot air chamber 11 passes through the grain flowing down the grain flow passage 13 that forms a large number of slits (not shown), acts on the grain, deprives the moisture, and is discharged into the exhaust air chamber 12. The exhaust fan 6 exhausts the exhaust duct 20 as exhaust air.

  Exhaust air in the exhaust air duct 20 is supplied to the heat exhaust air passage case 43 through the return duct 27 through a return duct 27 with an appropriate amount of return exhaust air by controlling the opening degree of the first control valve 23 and the second control valve 22. The hot air generated by the burner 5 is mixed and supplied.

  With the above configuration, the return exhaust air from the exhaust air fan 6 is mixed with the hot air generated by the combustion burner 5 and supplied to the hot air chamber 11, whereby heat in the exhaust air is added to the hot air supplied from the combustion burner 5. The heat can be appropriately applied to the grains in the grain flow passage 13, and the grain temperature can be increased to an appropriate temperature in a short time. Thereby, the water | moisture content transfer inside a grain or between grains can be made active, and high-speed drying can be performed, preventing the twisting of a grain. Moreover, since the absolute humidity of the hot air which acts on the grain of the grain flow path 13 becomes high, the amount of vaporization from the grain surface can be suppressed, and also in this respect, the grain can be prevented from being twisted.

  In addition, as a means to suppress the vaporization of moisture in the grain, the moisture once removed from the grain is returned to the grain and given to the grain, so there is no need for extra combustion to remove the newly humidified humidified water and fuel efficiency. Can be high.

  FIG. 7 is a system configuration diagram of the grain dryer 1 according to the embodiment of the present invention. The control device 17 is built in a control box above the burner case 40. As a signal input device to the control device 17, an outside air temperature sensor 70 installed on the outer periphery of the grain dryer 1, a hot air temperature sensor 71 for measuring the temperature of the hot air chamber, a moisture meter 10 provided in the grower 7, and a storage unit An extension amount detection sensor 72 provided at the upper portion of the inner wall 2 is provided, and the control device 17 receives these detection signals and also receives input signals from switches provided on the operation panel 16. Then, the control device 17 includes a combustion burner 5 that generates hot air to be fed into the hot air chamber 11, a first control valve drive motor 25 that drives the first control valve 23 and the second control valve 22 for adjusting the exhaust air amount, and a second control. Output devices such as a valve drive motor 26, a fan inverter 73 that adjusts the rotation speed of the fan motor 6d of the exhaust fan 6 and a power machine such as a grower motor that drives the grower 7 are connected to a signal input device. The operation of these output devices is controlled in accordance with the signal and the input signal from the switches.

  FIG. 10 shows a front view of the control panel 16 of the control box. The operation panel 16 has a status display panel 51 indicating the state of “heat recycling (registered trademark)” on the left side, an operation panel 52 indicating operation and status of main functions such as tensioning and drying in the center, and a grain tension on the right side. A sub-panel 53 that indicates the setting and state of the loading amount and the set moisture value of the grain is provided, and a grain setting and display, a drying speed setting and display button, and the like are provided below the sub-panel 53.

The outline of the operation control according to the embodiment of the present invention in the grain dryer 1 having the above configuration will be described.
The grain dryer 1 supplies the drying hot air to the drying unit 3 along the drying speed set by the user while circulating the grains stretched in the storage chamber 2, and sequentially performs the drying process to the drying target moisture. . The controller 17 of the grain dryer 1 performs a round measurement to measure the moisture value of the grain at a plurality of different timings according to the amount of tension while circulating the tension kernel in the storage chamber 2 once. Then, the moisture distribution state for each grain layer in the vertical direction of the cereal grains obtained by this round measurement, that is, the degree of moisture spots is grasped (see FIG. 8). Then, a planned circulation time required for the moisture spots to converge within a predetermined width by circulation of the grains is calculated, and a drying circulation operation is performed at a drying speed that reaches the drying target moisture within the scheduled circulation time.

Next, the 1st control processing of the control apparatus 17 concerning embodiment of this invention is demonstrated along a flowchart.
The grain dryer 1 performs step 1 to step 4 as a preparation stage of the drying operation. That is, the user presses the tension switch 61 on the operation panel 16 to tension the grain to be dried into the grain dryer 1 (S1). During the filling operation or after all the grains are stretched, the moisture value of the grains is automatically measured by the moisture meter 10 at a plurality of different timings, and the degree of moisture spots is grasped. (S2, S3). Then, the user sets the moisture value at the time of finishing the grain on the sub-panel 53 of the operation panel 16 and presses the grain selection switch 55 and the drying speed selection switch 56 to set the grain type and the desired drying speed. In addition, the approximate amount of grain is input. In accordance with the numerical value set or detected in the preparation stage, the drying operation time and the like are calculated by the control device 17, and the drying time is displayed on the second display portion 58 of the sub-panel 53 (S4).

  After completing the preparation stage of the drying operation, the user presses the drying switch 63 on the operation panel 16 to start the drying operation (S5). In the drying operation, the combustion burner 5 is burned and the exhaust fan 6 is driven according to the operation time calculated during the preparation stage. Further, the first control valve 23 serving as the exhaust air adjusting means is driven to adjust the ratio of the outflow exhaust air and the return exhaust air according to each stage of the drying operation (S6).

  Next, the control device 17 detects the actual amount of grain tension by a tension amount detection sensor 72 provided on the upper inner wall of the storage unit 2, and the control device 17 sets the preset tension amount set in advance. And the detected value are compared, and the next step is selected based on the result (S7). If the value is larger than the set amount (for example, 1 ton), the process proceeds to the next selection step. If the value is less than the set amount (for example, 1 ton), the rotational speed of the exhaust fan 6 is decreased. (S7a). In this case, the drying time and the exhausted air ratio are automatically calculated again using the reduced rotation speed, and the drying operation is continued with the calculated drying time and exhausted air ratio (S7b, S7c). In addition, when the detected value is equal to or less than the set insertion amount, the user also has a function of increasing or decreasing the exhaust rate. In this case, the fact that the detected value is less than or equal to the set amount is displayed on the second display portion 58 of the sub-panel 53, and the user presses the increase switch 59 or the decrease switch 60 to increase or decrease the rate of return exhaust air.

  When the control device 17 determines that the amount of tension is equal to or less than the set amount, the number of rotations of the exhaust fan 6 is decreased, so that hot air is blown out and stable drying can be performed. Further, the grain temperature can be increased while reducing the amount of hot air generated by the combustion burner 5.

  When the detected value is equal to or less than the set amount, by having a means for selecting the increase / decrease of the return exhaust rate by the exhaust wind adjusting means, increasing the exhaust wind rate by the exhaust wind adjusting means will reduce the exhaust heat. Since it can be used for that amount, it saves energy, and decreasing the exhaust air rate raises the grain temperature, so the drying rate can be improved. These can be appropriately selected according to the desire of the user.

  If it is determined that the detection value of the tension amount is larger than the set tension amount (S7), the control device 17 next determines whether or not the detected moisture spots are equal to or greater than a predetermined value and selects the next step (S8). . The “moisture spot” is “the moisture distribution state for each grain layer in the vertical direction of the stretched grain”, but “whether or not the moisture spot is equal to or greater than a predetermined value” has various judgment criteria for each apparatus. For example, the determination is made based on the difference between the maximum value and the minimum value of the moisture value of the grain layer, or based on the reference disclosed in Japanese Patent Application Laid-Open No. 2009-156481. When the moisture spots are smaller than a predetermined value, the operation is performed with the operation time and the exhaust air ratio calculated in the preparation stage of the drying operation (S9). If the moisture spots are not less than the predetermined value, the rotational speed of the exhaust fan 6 is decreased (S8a). In this case, the drying time and the exhausted air ratio are automatically calculated again using the reduced rotation speed, and the drying operation is continued with the calculated drying time and exhausted air ratio (S8b).

  When the control device 17 determines that the moisture spots are larger than a predetermined value, the air volume from the exhaust fan 6 is reduced by decreasing the rotational speed of the exhaust fan 6 and the grain temperature is increased. Thus, moisture transfer between grains in different moisture layers can be made smooth, and moisture spots for each grain layer can be reduced.

  Thus, the rotation speed adjusting means for changing the rotation speed of the exhaust fan 6 is provided, and the controller 17 adjusts the ratio of the return exhaust air by the exhaust air adjusting means during the drying operation, and the rotation speed adjusting means. By adjusting the rotation speed of the exhaust fan 6, the grain temperature can be easily adjusted, and drying in various drying forms can be performed.

  The control device 17 determines that the grain has reached the initially set moisture value by the arrival of the calculated drying time (S10), and ends the drying operation (S11).

  Next, the 2nd control processing of the control apparatus 17 in the grain dryer 1 of the said structure is demonstrated. The description of the same parts as the first control process is omitted.

  For the second control process, when setting the moisture value at the time of finishing, etc., a scheduled drying time at which drying ends is set (S4). This setting can be set by pressing the timer button on the sub-panel 53 of the operation panel 16 a plurality of times and switching to the screen for inputting the scheduled drying time and then pressing the increase switch 59 or the decrease switch 60. The scheduled drying time may be input from the actual time or the time from the set time. When the actual time is input, the controller 17 has a clock function. There is a need.

  Although the user's desired drying speed is input by the drying speed setting switch 56, the control device 17 manually inputs the amount of tension applied by the tension amount detection sensor 42 provided on the inner wall of the reservoir 2 or manually by the user. The time required for drying is calculated from the amount of tension applied, the detected moisture value detected from the moisture meter 10 provided in the groining machine 7, and the set drying speed, and the required drying time is within the scheduled drying time. If the required drying time is greater than the scheduled drying time, change the set drying speed and finish the calculation within the scheduled drying time. In step S5, a command for performing a drying operation is issued. The detected moisture value may be an average value of the whole in consideration of variation in detection, or may be a median value.

  If the required drying time is longer than the expected drying time, the drying of the grain is finished within the desired scheduled drying time by changing the set drying speed and performing the drying operation at the recalculated drying speed that is finished within the scheduled drying time. It is possible to manage the preparation facility efficiently by properly managing the time.

  In addition, the control device 17 detects the amount of tension detected by the tension amount detection sensor 42 provided on the inner wall upper portion of the storage unit 2, the detected moisture value detected from the moisture meter 10 provided in the groining machine 7, and the set dryness. In addition to the speed, the time required for drying while eliminating moisture spots due to moisture spots for each grain layer, that is, the time necessary for drying moisture spots to be dried is calculated, and this time required for drying moisture spots is scheduled to dry. If it is within the time, a message indicating that the drying is possible is displayed on the second display section as the notification means, and a command to perform a drying operation at a set drying speed is issued. If the time required for drying water spots is longer than the expected drying time, the second display will indicate that drying is impossible, and the user will select either the time priority mode or the drying speed priority mode. Then, a command to perform the drying operation in that mode is issued (S5).

  If the time required for drying moisture spots is longer than the expected drying time, the notification means notifies the user that drying is impossible, and the user selects either the time priority mode or the drying speed priority mode, and that mode. By performing the drying operation, the user can select the operation mode, and in the preparation facility, select the time priority mode when time is prioritized, and prioritize the drying speed that can save fuel when time is available The mode can be selected to properly perform the drying operation.

  In addition, when the drying speed priority mode is selected in the above, when the outside air temperature detected by the outside air temperature sensor 70 installed on the outer periphery of the grain dryer 1 is equal to or higher than the set value, at the end of the drying operation From time to time, the air is allowed to cool within the scheduled drying time, and when the outside air temperature is equal to or lower than the set value, the exhaust air adjusting means is controlled so as to return the exhaust air to the hot air chamber 11 side within the scheduled drying time.

  The control device 17 appropriately controls the exhaust air adjusting means according to the state of the outside air temperature, so that it is possible to save fuel for drying even when the drying time becomes long.

  A part of the second control process of the control device 17 can be applied to a grain dryer that does not perform exhaust air circulation.

  In the present embodiment, the fan inverter 73 is used as the rotation speed adjusting means for adjusting the rotation speed of the exhaust fan 6, but a stepping motor and a speed controller can also be used.

  When the control device 17 grasps the moisture distribution state for each grain layer in the vertical direction of the squeezed grain obtained by the round measurement, that is, the degree of moisture spots, the layer with high moisture is in the grain flow-down passage 13. It is also possible to increase the number of hot air by increasing the number of revolutions of the exhaust fan 6 and to increase the amount of combustion of the combustion burner 5 so as to eliminate moisture spots. Conversely, when there is a low moisture layer in the grain flow passage 13, the rotational speed of the exhaust fan 6 is reduced to reduce the amount of hot air, and the control to reduce the amount of combustion of the combustion burner 5 to eliminate moisture spots. It is also possible to perform. By such control, water spots can be appropriately removed.

  When the drying speed is set to be slow, the control device 17 can also perform control to reduce the amount of exhaust air by reducing the rotational speed of the exhaust fan 6. This makes it possible to reduce fuel consumption.

  The control device 17 can also perform control to perform the circulation work continuously from the tension work when the moisture spots are a predetermined value or more. In this case, the display function on the operation panel 16 displays that the moisture spots are not less than a predetermined value. In addition, when moisture spots are above a certain value, control to automatically ventilate after performing the tensioning operation, control to circulate and mix grains without wind after drying, circulation while reducing the drying speed and burning It is also possible to perform control to extend the time. Moisture spots are eliminated and overdrying can be prevented.

  In the state display panel 51 representing the magnitude of the return exhaust air rate, the display change threshold is changed based on the detected amount of tension. It is also possible to set the display change threshold of the state display panel 51 not by the ratio of the return exhaust air but by the temperature of the hot air chamber 11 and the fuel consumption of the fuel tank.

DESCRIPTION OF SYMBOLS 1 Grain dryer 2 Storage part 3 Drying part 4 Grain collecting part 5 Combustion burner 6 Exhaust fan 7 Graining machine 10 Moisture meter 11 Hot air chamber 12 Exhaust chamber 13 Grain flow lower passage 14 Rotary valve 16 Operation panel 17 Control device 20 Exhaust duct 21 Exhaust supply duct 22 Second control valve 23 First control valve 27 Return duct 70 Outside air temperature sensor 72 Tension amount detection sensor 73 Fan inverter

Claims (4)

Exhaust air returning means for returning exhaust air discharged from the exhaust air fan (6) to the hot air chamber (11),
An exhaust air adjusting means for adjusting a ratio of the outflow exhaust air discharged outside the machine and the return exhaust air returned to the hot air chamber (11);
A rotation speed adjusting means for changing a rotation speed of the exhaust fan (6),
During the drying operation, the control device (17)
Adjusting the rate of return exhaust by the exhaust control means; and
While adjusting the rotational speed of the exhaust fan (6) by the rotational speed adjusting means ,
By means of detecting moisture spots that are the moisture distribution state for each grain layer,
When the control device (17) determines that the moisture spots are larger than a predetermined value,
Grain dryer characterized in that the rotational speed of the exhaust fan (6) is reduced . When the control device (17) determines that the amount of tension is equal to or less than the set amount,
Grain dryer according to claim 1, characterized in that the rotational speed of the exhaust fan (6) is reduced. Exhaust air returning means for returning exhaust air discharged from the exhaust air fan (6) to the hot air chamber (11),
An exhaust air adjusting means for adjusting a ratio of the outflow exhaust air discharged outside the machine and the return exhaust air returned to the hot air chamber (11);
Means for selecting an increase / decrease in the rate of return exhaust air by the exhaust air adjusting means;
A rotation speed adjusting means for changing a rotation speed of the exhaust fan (6),
During the drying operation, the control device (17)
Adjusting the rate of return exhaust by the exhaust control means; and
While adjusting the rotational speed of the exhaust fan (6) by the rotational speed adjusting means,
When the control device (17) determines that the amount of tension is equal to or less than the set amount,
Grain dryer characterized in that the rotational speed of the exhaust fan (6) is reduced. 3. The grain dryer according to claim 2, further comprising means for selecting an increase / decrease in the rate of return exhaust air by the exhaust air adjusting means.

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