JP2019082262A - Dryer for crop - Google Patents

Abstract

To perform suitable combustion regardless of the shape of a burner without causing nozzle blocking even when plural kinds of fuel each having a different viscosity are used.SOLUTION: A dryer for crops equipped with a blower fan 52 for a burner for supplying combustion air and a combustion burner 7 comprising a nozzle 49 for supplying fuel is constructed in such a manner that a controller S is provided with fuel-type outputting means 46 of outputting information on whether kerosine is selected or light oil is selected as fuel to be used for controlling the amount of fuel to be supplied to the nozzle 49 in a preset range, so as to set the minimum supply amount of light oil F'mn greater than the minimum supply amount of kerosine Fmn.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a crop dryer for drying cereals and other crops.

  As a combustion burner of a dryer for agricultural products, a rotary burner or a gun type burner is used, and kerosene or light oil is used as a fuel (Patent Document 1). Also, in the rotary burner, when the viscosity of the fuel used is relatively high like light oil, the rotational speed of the burner vaporization cylinder is increased, and when the viscosity of the fuel used is relatively low like kerosene, the burner evaporation By controlling so as to reduce the number of revolutions of the cylinder, there is a configuration in which the vaporization of the liquid fuel is optimized regardless of the viscosity of the fuel used to increase the combustion efficiency (Patent Document 2).

JP, 2015-45488, A JP, 2008-190823, A

  However, in the technology of Patent Document 1, there is no consideration due to the difference in viscosity of the used fuel, and the technology according to Patent Document 2 is a technology focusing on the difference in viscosity, but for the rotary burner provided with a rotating vaporization cylinder It is a thing.

  The present invention seeks to realize appropriate combustion of the burner regardless of the form of the burner.

  The present invention takes the following technical measures in order to solve the above problems.

  According to the first aspect of the present invention, the kerosene is selected as the fuel used in the crop dryer provided with the combustion burner 7 having the burner fan 52 for supplying the combustion air and the nozzle 49 for supplying the fuel. The fuel type output unit 46 outputs whether or not the light oil is selected, and the fuel supply amount to the nozzle 49 is controlled to change in size within a preset range, and the minimum fuel supply amount F'mn of the light oil is kerosene. It is characterized in that it is set to be larger than the minimum fuel supply amount Fmn.

  According to the second aspect of the present invention, in the first aspect, the combustion burner 7 can execute an intermittent combustion operation in which the combustion step and the stop step are alternately performed, and a proportional combustion operation in which the fuel supply amount is variable. The rotational speed of the blower fan 52 for burners is set larger at the same fuel supply rate when selecting light oil than at the time of selecting kerosene.

  According to the invention described in claim 1, by setting the fuel type to two types, kerosene and light oil, crops can be dried with a wide range of fuels. Since the minimum fuel supply amount F'mn of the highly viscous light oil is set to be larger than the minimum fuel supply amount Fmn of kerosene, clogging of the nozzle 49 can be prevented.

  According to the second aspect of the invention, in addition to the effect of the first aspect, since the rotational speed of the blower fan 52 for burners is set larger than that of kerosene, the light oil having high viscosity can prevent the nozzle 49 from clogging.

It is a front sectional view of a grain drier. FIG. 2 is a side cross-sectional view of the drying room and the grain collection room of the grain dryer. It is a control board front view. It is a control block diagram. It is a combustion amount-fan rotation speed relationship graph. It is a flowchart. It is a flowchart. (A) is a time chart of proportional combustion operation, (B) is a time chart of intermittent combustion operation. It is a combustion amount-fan rotation speed relationship graph. It is a time chart. It is a combustion amount-fan rotation speed relationship graph. It is a flowchart. It is a time chart of intermittent combustion operation.

  A grain dryer as an embodiment of the present invention will be described based on the drawings.

  Inside the box 1, a storage chamber 2 for storing grains, a drying chamber 3 for drying grains, and a grain collecting chamber 4 are provided from the top to the bottom.

  An elevator 5 for raising grains and a burner case 6 are provided on the front side of the box 1, and a combustion burner 7 for generating hot air is provided in the burner case 6. An exhaust duct 9 communicating with the exhaust chamber 8 is provided on the rear side of the box 1, and an exhaust fan 10 is provided on the rear side of the exhaust duct 9. One end of the exhaust air return duct 11 is connected to the upper surface of the exhaust air fan 10, and the other end of the exhaust air return duct 11 is connected to the box 1. The exhaust air inlet 12 of the exhaust air return duct 11 is in communication with the inside of the exhaust air fan 10, and the exhaust air supply port 13 on the end side is in communication with the upper rear side of the hot air chamber 14 described later.

  In the upper part of the box 1 is provided an upper spiral weir 15 for laterally transporting the grain lifted by the elevator 5.

  The drying chamber 3 below the storage chamber 2 is provided with a pair of cross-sectional Y-type grain flowing passages 19 for further dividing the grain in the storage chamber 2 divided left and right into left and right. In the upper half of the drying chamber 3, a sub exhaust air chamber 8a is formed on the upper side of the left and right pair. Further, a hot air chamber 14 is provided at the left and right center portions of the drying chamber 3, and a far infrared radiator 16 is provided in the hot air chamber 14 along the front-rear direction. The above-mentioned grain flow down passages 19 and 19 where grains flow down are disposed on the left and right sides of the hot air chamber 14, and exhaust air flow chambers 8 and 8 are provided on the left and right sides of the grain flow down passages 19 and 19, respectively.

  A rotary valve 17 for feeding the grain is provided at the left and right junctions at the lower end of the grain flowing passage 19, and a lower helix 18 for conveying the grain to the elevator 5 is provided below the rotary valve 17.

  The burner case 6 has a large number of outside air intake slits for introducing outside air. The combustion burner 7 is equipped with a gun type burner 7 of the intermittent combustion type in the present embodiment.

  The exhaust fan 10 includes a rotary wing 20 rotating on a rotary shaft 20 a with a horizontal axis along the front-rear direction in the outer cylinder 24, a fixed wing 21 straightening exhaust air discharged from the rotary wing 20, and a rotary wing An inner cylinder 25 supporting the shaft 20 and an exhaust air guide plate 22 for guiding the exhaust air discharged by the rotary wings 20 to the exhaust air return duct 11 side.

  The fixed wing 21 is located on the exhaust air side rear of the rotary wing 20, and is provided with twisted air flow straightening surfaces on both the left and right sides, and provided in a large number at set intervals radially in a rear view. The outer end of the fixed wing 21 is attached to the outer cylinder 24, and the inner end of the fixed wing 21 is attached to the inner cylinder 25.

  An exhaust air control valve 26 is provided in the exhaust air return duct 11 to increase or decrease the amount of exhaust air flowing into the exhaust air return duct 11. The exhaust air adjustment valve 26 is configured to be adjustable in rotational angle about the horizontal axis in the left-right direction by the exhaust air adjustment valve motor 27. The exhaust air return duct 11 is a first duct portion 11 a extending upward from the upper surface of the exhaust fan 10, and a second duct extending in the front-rear direction connecting the upper end portion of the first duct portion 11 a and the back surface of the box 1 The exhaust duct control valve 26 is provided in the first duct part 11a. The second duct portion 11 b is configured to sequentially increase the opening area in a forwardly wide manner.

  The far-infrared radiator 16 is composed of a large diameter first cylindrical portion 30 and a small diameter second cylindrical portion 31. The rear portion of the first cylindrical portion 30 is formed as a constriction portion 30a, and the second cylindrical portion 31 is guided upward by being connected to the constriction portion via the start-end side bending portion, and is connected to the front side. The first cylindrical portion 30 and the second cylindrical portion 31 are both hollow, and the second cylindrical rod 31 is disposed above the first cylindrical portion 30 with a predetermined space in parallel in the front-rear direction.

  The front end opening of the first cylindrical portion 30 is disposed opposite to the combustion portion of the combustion burner 7, the front end of the second cylindrical portion 31 is closed by a plate, and the left lower Openings 31a are provided at predetermined intervals.

  An operation panel U incorporating a control unit S is provided on the front side surface of the burner case 6. As shown in FIG. 3, on the front side of the operation panel U, operation switches of a dip switch 32, a ventilation switch 33, a drying switch 34, a discharge switch 35, and a stop switch 36 are provided. Further, a liquid crystal operation display panel 45 is provided which sequentially switches and displays the temperature of the hot air, the measured moisture value, and the remaining time until the end of the drying operation during the drying operation.

  In addition, a setting display panel 39 for displaying setting numerical values of a built-in amount switch 37 for setting a built-in amount, a moisture setting switch 38 for setting an aimed target moisture value, a built-in amount switch 37 and a moisture setting switch 38 A numerical increase / decrease switch 40 for changing the set value of the display panel 39 is provided. In addition, a grain setting switch 41 for setting the type of grain to be dried and a drying speed setting switch 42 for setting the drying speed are provided.

  The hot air chamber 14 is provided with a hot air temperature detection sensor 43 for detecting the temperature in the hot air chamber 14, and an outside air temperature sensor 44 for detecting the outside air temperature at an appropriate position of the operation panel U.

  As shown in FIG. 4, various switches and sensors are connected to the input side of the control unit S via the input interface, and various motors and driving means are connected to the output side via the output interface.

  Next, combustion control and drying control by the exhaust air control valve 26 will be described.

  The combustion burner 7 of the present embodiment is a so-called gun type burner, which supplies combustion air by a blower fan 52, sprays a fuel drawn from a fuel tank (not shown) by a pump 50 from a nozzle 49, and igniter Fire at 51 and burn. The amount of fuel supplied from the pump 50 to the combustion burner 7 can be controlled by the proportional control valve 53, and the type of grain, the difference between the drying speed previously set by the setting switch 42 and the actual drying speed, the outside air temperature The control unit S calculates the necessary combustion amount of the burner for each predetermined unit time based on the above, calculates the fuel supply amount corresponding to this, and outputs the fuel supply amount command signal to the proportional control valve 53. . The above-mentioned proportional control valve is used when the combustion burner 7 needs a fuel supply amount larger than this based on the fuel supply amount Fa (liter / hour) preset by the performance unique to the device, etc. The necessary fuel supply amount Fb is calculated based on the control signal given to the engine 53 (proportional combustion operation). However, when the reference fuel supply amount Fa or less is required, the combustion burner 7 is switched to a so-called intermittent combustion operation in which the combustion process and the combustion stop process are alternately performed. The combustion state below the reference fuel supply amount Fa can be adjusted by changing the combustion process time Tb and the stop process time Ts with the cycle T (for example, 60 seconds) of the combustion process and the stop process in the intermittent combustion operation fixed. It has composition.

  As an example is shown in the combustion amount-fan rotational speed relationship graph of FIG. 5, in the proportional combustion operation of the combustion burner 7, the rotational speed of the blower fan 52 for the burner also increases or decreases in proportion to the change of the fuel supply amount. It is supposed to be controlled. Further, at the time of the intermittent combustion operation, in the combustion step, the rotation is controlled by selecting the lowest rotation number Ra of the combustion amount-fan rotation number table. Then, in the stop process in the intermittent combustion operation, as a configuration for selecting and rotating the preset rotational speed, the burner blower fan 52 is interlocked with the rotation continuously during the intermittent combustion operation. The fan rotation number in the combustion step and the stop step in the intermittent combustion operation may be the same or different.

  Next, the drying operation of the grain will be described.

  When the operator turns on the loading switch 32, the elevator 5 and the upper spiral 15 are driven to load the loaded grain into the storage chamber 2 sequentially. Then, when the loading operation is completed, the operator sets the amount of grain-in-place with the amount-of-placing switch 37, sets the target moisture value (for example, 14%) with the moisture setting switch 38, and targets with the grain setting switch 41. The grain is set, and the drying speed setting switch 42 is used to set the drying speed.

  Next, when the drying switch 34 is turned ON, the drying operation is started, and the circulation system of the rotary valve 17, the lower helix 18, the elevator 5, the upper helix 15 starts driving, and the combustion burner 7 starts combustion. The hot air generated by the combustion burner 7 passes through the inside of the far-infrared radiator 16 by the suction action of the exhaust fan 10, and enters the hot air chamber 14 from the openings 31a, 31a ... at the front end side of the second cylindrical portion 31. To flow. Then, it flows from the hot air chamber 14 into the grain flow-down passage 19 formed by the mesh body and acts on the grain. Then, the hot air which has deprived of the water from the grain flows into the exhaust air chamber 8, then passes through the exhaust air duct 9 and is exhausted as exhaust air outside the machine by the exhaust air fan 10.

  Part of the heat and moisture-laden exhaust air is supplied to the hot air chamber 14 through the exhaust air return duct 11 and reused for the drying operation. The grain is dried by the action of the hot air, the far infrared rays generated from the far infrared radiator 16, and the exhaust air returned from the exhaust air return duct 11.

  The exhaust air control valve 26 is adjusted based on the set grain size and drying rate, the grain moisture value measured by the moisture meter 54, the outside air temperature, and other conditions. For example, in order to raise the grain temperature at the initial stage of drying, the proportion of the external exhaust air returned to the exhaust air return duct 11 side is increased, and as the drying operation continues, the water value measured by the moisture meter 53 decreases. The rate of return to the wind return duct 11 side is gradually decreased, and the exhaust air control valve 26 is controlled so as to discharge almost all the exhaust air to the outside of the machine when approaching the reaching target water value.

  In the present embodiment, when the exhaust air control valve 26 is fully open, that is, even when the largest amount of exhaust air is supplied to the hot air chamber 14 through the exhaust air return duct 11, the exhaust air is a slit of the exhaust air guide plate 22. The ratio of the return exhaust air supplied to the hot air chamber 14 is about 4% of the total amount of exhaust air outside the machine, in order to pass 22a or pass between the fixed wings 21 in the portion where the exhaust air guide plate 22 is not attached. It is about a percentage.

  Next, based on the flowchart of FIG. 6, burner operation control in which the combustion burner 7 performs a proportional combustion operation or an intermittent combustion operation will be described. When the drying switch 34 is turned on, the status of each switch and sensor is read (S101, S102). The control unit S calculates the fuel supply amount F based on the type of grain, the moisture value, the drying rate, etc., and the calculated fuel supply amount F is compared with a preset reference fuel supply amount Fa. When the calculated fuel supply amount F exceeds the reference fuel supply amount Fa (S103), a fuel supply signal corresponding to the calculated fuel supply amount F is output to the proportional control valve 53 (S104). The rotational speed of the blower fan 52 is calculated, and the proportional combustion operation BL is performed (S106). On the other hand, when the calculated fuel supply amount F is less than the reference fuel supply amount Fa in S103, a supply signal of the minimum fuel supply amount Fmn set in advance is output to the proportional control valve 53 (S107) The number of revolutions 52 is set in the low range and outputted for revolution (S108). Further, the combustion process time Tb for the cycle T is calculated (S109), and the intermittent combustion operation is performed (S110). As described above, based on the comparison between the calculated fuel supply amount F and the reference fuel supply amount Fa, it is determined whether the proportional combustion operation or the intermittent combustion operation is performed. The heating condition can be changed and adjusted in a wide range over the high combustion area.

  In FIG. 6, when the stop switch 36 is turned ON or dried to the reaching target moisture value, the combustion burner 7 and each part of the operation are stopped (S111, S112), but the blower fan 52 for burners is rotated in a high range. The fan 52 continues the operation for a predetermined time (S113 to S115). When the stop switch 36 is turned on, S112 to S115 are executed regardless of proportional combustion operation or intermittent combustion operation. With this configuration, the combustion burner can be cooled rapidly.

  Next, control of the blower fan 52 for the burner will be described based on FIG. After the drying switch 34 is turned on, the control unit S determines whether the operation of the combustion burner 7 is proportional combustion operation or intermittent combustion operation (S201, S202), and if it is determined as proportional combustion control, the calculated fuel The supply amount F is read (S203). Then, a combustion amount-fan rotation number relationship graph as shown in FIG. 5 is called from the memory (S204). The fan rotation number is calculated from the combustion amount-fan rotation number relationship graph, and the rotation number is output to the blower fan motor 55 for driving the burner blower fan 52 (S205 to S207).

  If it is determined that the intermittent combustion operation is performed in S202, it is determined whether the combustion process or the stop process is performed (S208). If it is determined that the process is a combustion process, reading of the amount of supplied fuel (S209) and a graph of the relationship between the amount of combustion and the fan rotational speed are called from the memory (S210). The minimum fan rotational speed Rmn is calculated from the combustion amount-fan rotational speed relationship graph (S211), and the rotational speed is output to the drive motor 55 for driving the burner fan 52 (S212). Then, the blower fan 52 is rotated until the combustion process time Tb elapses (S213, S214). If it is determined that the step S208 is the stopping step, the fuel supply to the combustion burner 7 is shut off and the combustion is stopped, but the number of revolutions stored in advance as the fan revolution number, for example, the lowest fan revolution number Rmn is called out. The blower fan 52 is rotated until the stop process time Ts elapses (S215 to S218).

  Thereafter, when the operation of the stop switch 36 is turned on or the target moisture value is dried, the combustion burner 7 is stopped (S219, S210), and thereafter S112 to S115 in FIG. 6 are executed (S220 to S223).

  The determination of whether the combustion burner operation at S202 is a proportional combustion operation or an intermittent combustion operation depends on whether the calculated fuel supply amount exceeds a reference fuel supply amount, and the combustion at S208 is performed. The determination as to whether it is a step or a stop step is made so as to execute the combustion step immediately after the passage of time in S218, and it is judged to carry out the combustion step immediately after the passage of time in S214.

  By the way, in the drying control, there is a drying control method in which a pause drying operation is performed for the purpose of eliminating the uneven drying during the normal drying operation. In the pause drying operation, the combustion burner 7 is stopped, and the blower fan 52 for the burner is configured to continue operation in a predetermined rotation region for a predetermined time during the pause drying operation. At this time, if the combustion immediately before the pause drying operation is an intermittent combustion operation, the burner fan 52 performs an operation for a predetermined time in a low rotation region below a predetermined value, and in a proportional combustion operation The operation is performed for a predetermined time by the rotation area. For this reason, it can shift to rest drying smoothly.

  The time chart shown in FIG. 8 shows the state of the averaging process and the display output of the hot air temperature of the proportional combustion operation and the intermittent combustion operation. FIG. 8A shows the display output of the fuel supply amount, the hot air temperature, the moving average value MRn (n = 1, 2...) Of the hot air temperature and the moving average value MRn during proportional combustion operation, and has a predetermined period The display of the moving average value MRn is updated every Td. On the other hand, FIG. 8B shows an example of the fuel supply amount at the time of intermittent combustion operation, the temperature of the hot air, the moving average value MIn (n = 1, 2...) And the moving average value MIn displayed.

  The moving average value display is performed at every cycle Td both at the time of proportional combustion operation and at the time of intermittent combustion operation. Therefore, the operator should remember this common cycle Td regardless of whether it is in proportional combustion operation or intermittent combustion operation, and the next judgment such as abnormality etc. will not be missed next time in judgment such as abnormality judgment etc. It can be done.

  Then, the moving average value MRn or MIn immediately before the display output timing in the cycle Td is adopted and displayed on the operation display panel 45. The moving average value MIn in the intermittent combustion operation is calculated and processed as follows. The detection data from the hot air temperature detection sensor 43 is only during the combustion process and not during the stop process. The moving average value MIn is displayed for each cycle Td, but the moving average value MIn immediately before the display output timing according to the cycle Td is adopted and displayed on the operation display panel 45. The values of MI1 and MI5 in FIG. 8B are immediately displayed, but MI3 and MI7 are continuously displayed. Arrows in FIG. 8B indicate relationships that are adopted and displayed based on the display output.

  In addition, as shown in FIG. 13, you may employ | adopt not a moving average value but a simple average value. In this case, for example, the average temperature may be measured at the time of the combustion process during the intermittent combustion operation, and the display output may be performed during the stop process.

  Although the example of FIG. 9 shows the case of the kerosene fuel normally used for the combustion burner 7 of a crop dryer, it can replace with kerosene and can also use light oil. A combustion amount-fan rotation number relationship graph in the case of using light oil is shown by a dotted line in FIG. In the case of highly viscous light oil, the fan rotational speed is set to be slightly higher than that of kerosene (solid line in FIG. 11). Further, the minimum fuel supply amount Fmn is set such that the minimum fuel supply amount F'mn of light oil is slightly larger than the minimum fuel supply amount Fmn of kerosene. That is, in the case of light viscous oil with high viscosity, it is possible to prevent fuel clogging of the nozzle 49 by limiting the fuel supply state on the lowest side.

  In the present embodiment, since the execution of the minimum fuel supply amount Fmn or F'mn is in intermittent combustion operation, the fuel process time Tb is corrected on the plus side and the fuel is compared with the case of kerosene in the case of light oil. The supply amount is different. When the intermittent combustion operation is not employed, the same configuration can be made during proportional combustion operation.

  As described above, the minimum fuel supply amount Fmn is set so that the minimum fuel supply amount F'mn of light oil is slightly larger than the minimum fuel supply amount Fmn of kerosene, and the difference of .DELTA.Fmn is obtained. For this reason, in the case of light oil with high viscosity, the fuel clogging of the nozzle 49 can be prevented in advance by setting the fuel supply state on the lowest side higher by .DELTA.F.sub.mn than kerosene.

  The control unit S is provided with a kerosene / light oil selection switch 46. When kerosene is selected and set, the solid line side of the combustion amount-fan rotation number of FIG. 11 is adopted, fuel supply amount control and corresponding fan rotation number control When the diesel fuel is selected and set, the dotted line side in FIG. 11 is adopted. The fuel supply amount control is based on the fuel supply signal from the control unit S to the proportional control valve 53 of the kerosene or light oil selected for the nozzle 47, and the fan rotational speed control drives the burner fan 52 This is based on the output of the fan rotational speed signal from the control unit S to the blower fan motor 55.

  Fuel selection and drying control will be described with reference to FIG. The drying switch 34 is turned ON to read the status of each switch and sensor (S201, 202). Among the switches, the selection output of the kerosene / light oil selection switch 32 is input (S203). At the start of drying, the initial fuel supply amount and the initial fan rotational speed are called in advance (S204, S205). In this state, the initial combustion operation, that is, the combustion burner 7 is ignited and burned (S206). At the same time, it is determined based on the input of S203 whether or not the selected fuel is kerosene selection (S207). When kerosene is selected, the solid line side showing kerosene out of the combustion amount-fan rotational speed of FIG. A proportional combustion operation or an intermittent combustion operation is performed according to the amount (S209).

  When it is determined in S207 that light oil is selected, the dotted line side indicating light oil among the combustion amount-fan rotation speed in FIG. 11 is adopted (S210), and the operation of the combustion burner 7 and the like is performed.

  During the drying operation while the combustion burner 7 is in operation, the fuel supply amount F is calculated from the difference between the hot air temperature Tb by the hot air temperature detection sensor 43 and the preset hot air temperature Tc set in advance (S211, S212). It is determined whether the fuel supply amount F calculated here is the minimum fuel supply amount Fmn of kerosene or the minimum fuel supply amount F'mn of light oil (S213, S214), and the supply is output (S215, S216) ). If it is not the minimum fuel supply amount at S213, the calculated supply amount F is output (S217).

  When the grain moisture reaches the predetermined finish moisture or the stop switch 36 is turned on (S218), the combustion burner 7 and the blower fan 52 for the burner are stopped and output (S219, S220).

  If it is determined in S207 that the light oil is selected, the dotted line side indicating the light oil is employed among the combustion amount-fan rotation speed in FIG. 11 (S213). The operation of the combustion burner 7 and the like is executed in the following steps S209 to S212.

  Although the predetermined fuel supply amount and burner fan rotational speed were adopted regardless of the difference in fuel type in S204 and S205, different initial fuel supply amount and initial fan rotational speed may be set for each kerosene or light oil. May be

  As shown in FIG. 11, by setting the fan rotational speed of light oil to be slightly larger than that of kerosene at the same combustion amount, ie, fuel supply amount, the shortage of primary air can be prevented and stable combustion can be performed. .

  As described above, in the present embodiment, the fuel type output unit that outputs whether the control unit S has selected kerosene or light oil as the fuel used, is configured by the kerosene / light oil selection switch 46, but It may be configured by an identification sensor that identifies kerosene / light oil. The identification sensor may be configured to include color identification means capable of recognizing the color of colorless and transparent kerosene and light yellow (or light yellowish green) light oil.

  Next, with reference to FIG. 10, a specific example of the supply amount increase / decrease output accompanying proportional combustion control will be described in relation to the detection output of the hot air temperature Tb. The fuel supply amount F (fuel may be either kerosene or light oil) is output to the proportional control valve 53 in an increase or decrease based on the difference between the set hot air temperature Tc and the detected hot air temperature Tb. That is, when the hot air temperature Tb detected by the hot air temperature detection sensor 43 is lower than the set hot air temperature Tc, a fuel increase signal is output, and when it is high, a fuel decrease signal is output. The fuel increase signal or the fuel decrease signal is configured to increase or decrease stepwise every unit amount q (for example, 0.1 liter / hour) at unit time t (for example, one minute). For example, even if the fuel supply amount is calculated by +4 q more than the current fuel supply amount by the difference ΔTb between the detected hot air temperature Tb and the set hot air temperature Tc, the supply amount of +4 q does not increase at once. Control is performed so as to increase 1q, 2 × q, etc. every t. In the case of the decrease output, as in the increase side, the supply amount decrease −q, −2 × q is output at every unit time t.

  When a gun type burner is employed as the combustion burner 7, the reaction to the increase and decrease in fuel speed is fast, and when the fuel supply amount is increased at once, the hot air temperature rises rapidly, and excessive hot air is supplied to dried agricultural products, which is undesirable in quality . However, by setting the amount of increase or decrease of the fuel supply amount per unit time to the unit amount and changing it stepwise as described above, the quality does not deteriorate.

  The control unit S outputs a fuel supply amount change request every unit time t, and when this request signal is output, the fuel supply amount is calculated from the difference between the set hot air temperature Tc and the detected hot air temperature Tb, and proportional The supply amount increase / decrease to the control valve 53 is output. As shown in FIG. 10, this request signal is executed in the first half of the unit time t, and the supply amount increase / decrease output is maintained during the unit time t. Further, the control unit S is configured to output a hot air temperature detection request, and to receive a detection output from the hot air temperature detection sensor 43 that detects the hot air temperature Tb to be sequentially changed when receiving the request signal. This hot air temperature detection request is configured to be executed in the second half of the unit time t, that is, it is possible to grasp the fluctuation state of the hot air temperature Tb immediately after the supply amount is increased or decreased by the change output. The temperature rise or fall can be confirmed within t / 2 hours in the second half of the unit time t, and it is possible to grasp an excessive rise in temperature or a situation where it should not fall down but prevent grain damage and prevent accidents such as fires. It can be prevented in advance.

  In the time chart showing the change characteristic of the hot air temperature Tb in FIG. 10, a threshold of a predetermined width ± α is provided above and below the set hot air temperature Tc, and a known configuration which suppresses the increase / decrease control when it falls within the threshold ± α. And

7 Combustion burner 46 Kerosene / light oil selection switch (fuel type output means)
49 Nozzle 52 Burner fan Fa Reference fuel supply amount MRn Hot air temperature average (during proportional combustion operation)
MIn hot air temperature average value (during intermittent combustion operation)
Fmn Minimum fuel supply (kerosene)
F mn mn Minimum fuel supply (diesel oil)

Claims (2)

  In a crop dryer equipped with a burner fan (52) for burner air that supplies combustion air and a burner (7) equipped with a nozzle (49) that supplies fuel, kerosene is selected as the fuel used or light oil is selected. A fuel type output unit (46) for outputting the selected fuel is configured to change the fuel supply amount to the nozzle (49) to a large or small size within a preset range, and the minimum fuel supply amount of light oil (F'mn ) A dryer for crops characterized in that it is set larger than the minimum fuel supply amount (Fmn) of kerosene.   The combustion burner (7) is provided so as to be able to execute an intermittent combustion operation in which the combustion process and the stop process are alternately performed and a proportional combustion operation in which the fuel supply amount is variable. The crop dryer according to claim 1, wherein the rotational speed of the blower fan (52) is set larger than that at the time of selection.

Images