JP5251029B2 - Kernel drying method - Google Patents

Description

The present invention relates to a method for drying grain .

Patent Document 1 describes a drying apparatus that returns exhaust air and joins it with hot air to dry it.
JP 2007-10247 A

  Patent Document 1 describes the content of adjusting the amount of exhaust air as much as possible to reach the target exhaust absolute humidity, but does not describe what exhaust air absolute humidity should be used for drying. Therefore, there is room for improvement in order to continuously and stably perform a drying method of drying at high speed and preventing cracking of the grain.

In order to solve the above problems, the present invention has taken the following technical means.
That is, the invention according to claim 1 is a drying unit that dries hot air for drying on the grain ,
A return means for merging the exhaust air after passing through the grains with the hot air for drying,
The combined air of the hot air for drying and the return exhaust air acting on the grain supplies the return exhaust air near the saturated water vapor pressure and does not exceed the saturated water vapor pressure ,
Store the correspondence relationship between the absolute wind humidity and the grain moisture value in the storage unit of the control unit in advance,
The amount of return exhaust air is a grain drying method that is controlled based on the grain moisture value detected during drying .

The invention according to claim 2, grain drying according to claim 1, wherein the correcting the amount of return exhaust air to set the relationship between the water content of the exhaust air absolute humidity and grain by Chokomi amount of increase or decrease The method .

The invention according to claim 3 is the grain drying method according to claim 1, wherein the amount of return wind set based on the relationship between the absolute wind exhaust humidity and the moisture value of the grain is corrected by the level of the outside air temperature. .

The invention according to claim 4 is the grain drying method according to claim 1, wherein the return exhaust air amount set from the relationship between the exhaust wind absolute humidity and the moisture value of the grain is corrected by the drying speed .

In the invention of claim 1, the saturated vapor pressure condensation beyond and grain is stuffy to the extent not to impair the quality, the heat and moisture contained in the exhaust air by giving the grains, grains inside many It is possible to reduce the water gradient inside the grain by supplying the heat of the grain and by suppressing the moisture that is going to evaporate from the surface of the grain to the inside of the grain by the moisture in the exhaust air that has been absorbed from the grain. it can. Therefore, it is possible to make cracks and the like difficult to occur inside the grain while being dried at high speed.

In addition, by adjusting the amount of return exhaust air in accordance with the moisture content of the grains detected during drying, a humidity sensor that detects the exhaust air humidity is not required, and the cost is not increased. Can be dried while feeding to the grain .

In invention of Claim 2-4, in order to correct | amend the control which adjusts according to the water | moisture-content value of the grain which detects the amount of return exhaust air during drying according to outside temperature, the amount of tension grain, and a drying speed The amount of exhaust air suitable for various conditions can be returned.

The case where this Embodiment is used for a grain dryer is demonstrated.
FIG. 1 is a perspective view for explaining the inside of a grain dryer, in which a grain storage unit 2 that stores grains from above in a rectangular parallelepiped main body 1 and drying while flowing down the grains stored in the storage unit 2. A drying unit 3 to be collected, and a cereal collecting unit 4 to collect the grains dried by the drying unit 3 are provided. And the grain stuck in the storage part 2 is dried by the drying part 3 and supplied to the cereal collecting part 4, and the structure of what is called a circulation type grain dryer of the structure supplied to the storage part 2 and tempered again. It is.

In the present embodiment, the longitudinal direction s of the main body 1 is referred to as the front-rear direction, and the short direction t is referred to as the left-right direction.
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 in the front-rear direction of the main body 1 and in the middle of the left and right sides facing the drying unit 3. Is arranged. The combustion burner 5 is placed so that the combustion disc surface 5d of the combustion burner 5 faces the main body 1 side.

On the rear side in the front-rear direction of the main body 1, a wind exhaust fan 6 is provided at the left and right center position facing the drying unit 3.
Further, an elevator 7 for raising the grain is provided at a position adjacent to the burner case 40 on the front side in the front-rear direction of the main body 1, and a transfer spiral (not shown) is provided on the upper portion of the main body 1. An upper conveying device 8 that conveys the cerealed grains to the storage unit 2 and a dust suction fan 9 that sucks and removes foreign matters such as scum mixed in the grains being conveyed by the upper conveying device 8 are provided.

  10 is a moisture meter that detects the moisture of the grain. The moisture meter is attached to the elevator 7 and calculates the moisture value by taking in the sample grain from the grains being grained and detecting the electrical resistance value for each grain every set time. To do.

  The drying unit 3 is provided with hot air chambers 11 through which dry hot air generated by the combustion burner 5 passes on both left and right sides of the main body 1, and is provided with exhaust air chambers 12 communicating with the exhaust fan 6 at the left and right central portions of the main body 1. A grain flow passage 13 is provided between the chamber 11 and the air discharge chamber 12, and a rotary valve 14 that feeds the grain to the grain collection unit 4 is provided at the lower end of the grain flow passage 13. Therefore, the grains in the storage chamber 2 pass through sequentially.

The cereal collection unit 4 is provided with a lower spiral 15 that conveys the grains to the elevator 7.
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.

In the exhaust duct 20, a first control valve 23 that adjusts the ratio of the amount of exhaust air discharged to the outside of the exhaust duct 20 and the exhaust air supply duct 21 is provided.
An exhaust air supply duct 21 having a square cross section for supplying exhaust air to the inside of the main body 1 is provided at the upper part of the exhaust air duct 20, and the exhaust air inlet of the exhaust air supply duct 21 is supplied into the exhaust air supply duct 21. A second control valve 22 is provided for adjusting the amount of exhausted air.

  The first control valve 23 and the second control valve 22 are configured to be rotated by a horizontal axis pivot shaft 23a and a pivot shaft 22a, respectively, of which the control valve drive motor 25 is connected to the pivot shaft 23a. Yes. The 1st control valve 23 and the 2nd control valve 22 are connected with the connection rod 24, and it is set as the structure which the rotation operation of the 1st control valve 23 and the 2nd control valve 22 interlock | cooperates. When the second control valve 22 is in the fully closed position ga and exhaust air is not discharged into the exhaust air supply duct 21, the first control valve 23 is in the fully open position fa and all exhaust air is discharged outside the machine.

  On the other hand, when the second control valve 22 is in the fully open position gb and the exhaust air is discharged most into the exhaust air supply duct 21, the first control valve 23 exhausts the most exhaust air. It is located at the closed position fb for discharging the exhaust air to the wind supply duct 21 side. In addition, the 1st control valve 23 and the 2nd control valve 22 are set as the structure which can be opened / closed steplessly, respectively, and the exhaust_gas | exhaustion amount discharged | emitted to the exhaust_gas | exhaustion supply duct 21 is adjusted with the control part F suitably.

  As described above, the rotation angle θ of the first control valve 23 is determined by calculating the exhaust air return amount, and the adjustment valve is driven until the rotation angle θ is detected by the angle detection sensor 23b incorporated in the shaft 23a. The motor 25 is configured to be linked in the forward / reverse direction. Since the second control valve 22 is linked to the first control valve 23, the rotation angle of the second control valve 22 is not detected. However, the second control valve 22 is configured to independently rotate and adjust both control valves. In this case, an angle detection sensor and a control valve drive motor are provided.

  When the first control valve 23 is at the closed position fb for discharging the exhaust air to the exhaust air supply duct 21 side most, the lower inner peripheral surface 20a of the exhaust air duct 20 and the first adjustment plate 23 The length b from the rotating shaft 23a to the outer periphery of the first control valve 23 is shorter than the length from the center of the exhaust duct 20 to the inner peripheral surface 20a so that a gap z with a set interval is formed between the peripheral edge 23a. The area of the first control valve 23 is smaller than the opening area of the exhaust duct 20. j is a turning locus of the first control valve 23;

  The closed position fb where the first control valve 23 discharges the most exhausted air to the exhaust air supply duct 21 side is configured to be located at a downward slope as shown in FIG. 22 is configured to be positioned at a rearward downward inclination, so that the exhausted air can be easily guided into the exhausted air supply duct 21.

  Between the exhaust air supply duct 21 and the main body 1, an exhaust air distribution case 26 serving as an exhaust air distribution passage that distributes the exhaust air that has passed through the exhaust air supply duct 21 to the left and right sides is provided from the top of the exhaust air fan 6 Provided on both sides. The left and right end portions of the exhaust wind dispersion case 26 and the rear end portion of a return duct 27 that forms a hot air chamber through-passage to be described later are configured to communicate with each other through a first exhaust wind opening m.

The return duct 27 is a cylindrical passage provided along the front-rear direction in the left and right hot air chambers 11 and is formed in a trapezoidal shape with a cross-sectional shape and a sharp upper portion in the present embodiment.
Between the main body 1 and the burner case 40, there is formed a first return passage 41 through which exhaust air returned through the main body 1 passes and a hot air passage 42 through which hot air generated by the combustion burner 5 passes. An exhaust passage case 43 is provided. And while setting it as the structure which connects the end of the return duct 27, and the 1st return path 41 with the 2nd ventilation opening part p, the 2nd return path 44 formed in the left-right both sides of the 1st return path 41 and the burner case 40 And the third exhaust opening r. A dust storage case 45 is formed below the burner case 40. A fourth exhaust opening d is formed at the upper left and right ends of the dust storage case 45 so as to communicate with the second return passage 44.

The configuration of the heat exhaust air passage case 43 will be described in detail.
The hot air passage 42 in the hot exhaust air passage case 43 includes a first hot air passage 46 communicating with the burner case 40 and the first hot air opening c, and hot air that has passed through the first hot air passage 46 from the second hot air opening v. A second hot air passage 47 that supplies the hot air chamber 11 through the third hot air opening w is provided.

  The first return passage 41 and the second hot air passage 47 are formed on the front left and right sides of the main body 1 and are formed in two upper and lower stages, and the first hot air passage 46 is provided at a position facing the burner case 40 on the left and right center side. ing. The first hot air opening c is formed at the center of the first hot air passage 46 and the burner case 40.

In the present embodiment, a path through which the exhaust air from the exhaust air supply duct 21 to the second return passage 44 passes is collectively referred to as a return passage.
The surroundings of the combustion burner 5 will be described.

  A second return passage 44 provided in the burner case 40 and adjacent to the left and right of the combustion burner 5 is provided with a fifth exhaust opening e for exhausting exhaust air. The position of the fifth exhaust air opening e is provided from the combustion disk surface position k of the combustion burner 5 toward the main body 1 and is formed in a number of slit shapes. And the 5th exhaust wind opening e is formed so that the main body 1 side may be opposed like the combustion disk surface 5d of the combustion burner 5.

  Then, the exhaust air discharged from the fifth exhaust air opening e and the hot air generated by the combustion burner 5 are mixed in the heat exhaust air mixing unit 40a located on the combustion flame Q side of the combustion burner 5 and mixed heat. The exhaust air passes through the hot air passage 42, that is, the first hot air passage 46 and the second hot air passage 47 in this order, and is supplied to the hot air chamber 11.

Moreover, as shown in FIG.7 and FIG.8, many slits are formed in the 5th wind exhaust opening e toward the main body lower side.
A burner fan 5a that sucks the primary air of the combustion burner 5 and supplies it to the combustion burner 5 is provided above the combustion burner 5 and on the main body 1 side from the combustion disk surface position k. And the air can be blown to the combustion burner 5 through the air duct 5b.

Reference numeral 70 denotes a wind detection plate that detects the presence or absence of a wind flow. A combustion pump 5 c supplies combustion to the combustion burner 5.
A slit-like combustion flame confirmation opening 43a for confirming the state of the combustion flame Q is provided on the side wall of the heat exhaust air passage case 43, so that not only the state of the combustion flame can be confirmed but also outside air can be introduced, so The side walls are not easily heated by the heat of the wind passage case 43.

  Next, after the hot air generated in 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, it becomes exhaust air and becomes the exhaust air chamber 12 and the return passage. The process until the hot air is mixed with the hot air and supplied to the hot air chamber 11 will be described.

  The hot air generated by the combustion burner 5 passes from the burner case 40 through the first hot air opening c, and from the first hot air passage 46 through the second hot air opening v, the second hot air passage 47, and the third hot air opening w. And supplied 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 duct 20 is supplied to the exhaust air supply duct 21 so that a necessary exhaust air amount is appropriately circulated to the hot air chamber 11 side through the return passage by controlling the opening degree of the first control valve 23 and the second control valve 22. To be supplied.

  The exhaust air supplied to the exhaust air supply duct 21 is dispersed left and right by the exhaust air distribution case 26 and supplied to the return duct 27 from the first exhaust air opening m. The exhaust air in the return duct 27 passes through the second exhaust passage opening p, the first return passage 41, the third exhaust passage opening r, the second return passage 44, and the fifth exhaust passage opening e to the combustion burner 5. Is discharged from the side of the combustion flame Q in parallel with the direction in which the combustion flame Q is ejected, and mixed with hot air in the hot exhaust air mixing portion 40a located at the position facing the combustion burner board surface, from the first hot air opening c. It is supplied to the first hot air passage 46. The dust contained in the exhaust air from the second return passage 44 falls by its own weight, passes through the fourth exhaust air opening d, and is stored in the dust storage case 45.

Next, operations and effects associated with the configuration of the present embodiment will be described.
By supplying the exhaust air from the exhaust fan 20 to the hot air chamber 11, the heat in the exhaust air is added to the hot air supplied by the combustion burner 5, and the hot air chamber 11, and hence the grains in the flow-down passage 13, can be made short. Grain temperature can be increased over time. And the absolute humidity of the dry hot air which acts on the grain of the grain flow down passage 13 can be increased by controlling the return amount of the exhaust air, and the amount of vaporization from the grain surface can be suppressed.

  When dry hot air mixed with exhaust air is supplied, the amount of vaporization that evaporates from the grain surface is suppressed by the absolute humidity on the grain surface, while the heat acting on the grain mainly promotes the rise in grain temperature. In addition, the moisture fluidity in the grain can be improved, the moisture gradient between the inside and the surface side of the grain unit can be reduced, the cracking of the body can be reduced, and the drying operation can be performed at high speed.

  Moreover, in this Embodiment, as what suppresses the vaporization of the water | moisture content in a grain, it does not humidify a grain using another humidifier as described in Unexamined-Japanese-Patent No. 7-260351, for example, Since the moisture once removed from the grain is returned to the grain and given to the grain, it is possible to perform high-speed drying while eliminating the need for extra combustion for removing the newly-humidified humidified moisture and having good fuel efficiency.

  Further, when the first control valve 23 is in the closed position fb where the amount of exhaust air is exhausted to the exhaust air supply duct 21 side, the lower inner peripheral surface 20a of the exhaust air duct 20 and the first adjustment plate 23 By configuring the area of the first adjustment plate 23 to be smaller than the opening area of the exhaust duct 20 so that a gap z is formed between the end 23 b and the exhaust duct 20, relatively large dust contained in the exhaust air can be removed. z is easily discharged out of the machine, dust can be made difficult to accumulate in the exhaust air circulation passage from the exhaust air supply duct 21 to the third return passage 45, and the exhaust air can be smoothly passed. Can do. Further, since the exhaust air supply duct 21 is located above the exhaust air duct 20, it is difficult for large dust to enter the exhaust air supply duct 21 and to be easily discharged outside the apparatus.

  By providing the return duct 27 in the hot air chamber 11, the temperature inside the return duct 27 is also increased, and high humidity exhaust air containing dust is prevented from condensing inside the return duct 27 and adhering dust. be able to. In addition, if a passage for passing the exhaust air is provided in the exhaust air chamber 12, the space of the exhaust air chamber 12 is reduced and the suction force of the exhaust air fan 6 is reduced. However, by providing it in the hot air chamber 11. This can be prevented by this embodiment.

  The hot air chambers 11 are provided on both the left and right sides of the main body 1 and the exhaust air chamber 12 is provided at the center of the main body 1 so that when the outside air temperature is low, a high-temperature and high-humidity mixture of exhaust air and hot air is discharged. It is possible to make it difficult for the inside of the exhaust chamber 12 passing as wind to condense.

  Before the exhaust air is supplied from the return duct 27 to the first hot air passage 46, combustion is performed from the fifth exhaust air opening e to the side of the combustion flame Q of the combustion burner 5 through the second return passage 44 adjacent to the burner case 40. By discharging the exhaust air to the heat exhaust air mixing unit 40a in parallel with the jet direction of the flame Q, the combustion flame Q does not flow turbulently and the combustion of the combustion burner 5 can be performed stably. In addition, since the exhaust air is merged on the combustion side of the combustion burner 5, the change in the amount of wind passing around the combustion burner 5 due to the change in the return exhaust air amount can be reduced, and the change in the combustion flame Q can be reduced. it can. And mixing of exhaust air and hot air can be promoted. Further, by not directly exposing the exhaust air to the combustion burner 5, it is possible to prevent the combustion burner 5 from being deteriorated due to the action of dust, moisture, or the like.

  Further, a large amount of dust being exhausted can fall and accumulate in the dust storage case 45, and the amount of dust supplied to the first hot air passage 46 and the hot air chamber 11 can be reduced. By providing the return passage adjacent to the burner case 40, the heat retention of the exhaust air can be improved.

  As in the present embodiment, in a dryer that directly heats the outside air with the combustion burner 5 and supplies the air contained in the combustion gas to the object to be dried, the exhaust air containing dust is discharged from the combustion flame of the combustion burner 5. Dust burns when heated by Q, and the burned dust is supplied to the grain and the quality of the grain has been reduced. According to this embodiment, the quality of the grain is difficult to burn dust. A decrease can be prevented.

Next, the drying control of this embodiment will be described.
FIG. 9 is a graph showing a change in grain temperature and a change in moisture value accompanying a drying operation, L1 shows the drying process of the present embodiment, and L2 shows a conventional drying process. L3 indicates a change in the moisture value of the present embodiment, and L4 indicates a conventional moisture value process.

  L2 is a graph when the combustion burner 5 makes the combustion amount constant in the conventional drying process, but the grain temperature gradually rises after starting combustion, and the grain temperature is substantially constant until reaching the finish moisture. It shows that it is rising with a slope.

On the other hand, the drying process of L1 performs the following processes.
First, after the combustion of the combustion burner 5 is started, the first adjustment plate 23 is fully opened for a predetermined time (for example, the time during which the cereal grains circulate once), and the exhaust air is discharged almost entirely outside the apparatus. A large amount of generated dust is prevented from being supplied again from the return passage into the hot air chamber 11 (dry initial full amount outside-machine discharge step A1).

  When the predetermined time has elapsed, the first adjusting plate 23 and the second adjusting plate 22 are adjusted so that the ratio of the exhausted air to be returned remains constant for a while in a state of a predetermined value or more (for example, 75% or more). Most of the exhaust air is discharged to the return passage side and supplied into the heat exhaust air mixing unit 40a. And it is mixed with the exhaust air and the hot air generated in the combustion burner 5 and supplied from the hot air chamber 11 to the grains in the flow-down passage 13 (dry initial total amount returning step A2).

  For this reason, moisture that evaporates from the surface of the grain by the supplied heat is suppressed by the moisture supplied together with the heat, and the moisture stays inside the grain. The grain temperature is given to the grain by adding the heat of the exhaust air to the heat generated by the combustion burner, so that a lot of heat is given and the grain temperature rises rapidly.

  In this step, the return amount is corrected by the outside air temperature, and the first adjusting plate 23 and the second adjusting plate 22 are adjusted so that the ratio of the exhaust air to be returned is lowered as the outside air temperature becomes higher. Moreover, this process is a process of returning the most exhausted air in the entire drying process.

  Then, the adjustment which returns the exhaust wind of the exhaust wind absolute humidity Ha containing the moisture content according to the grain moisture value detected with the moisture meter 10 for every set time is performed (exhaust wind absolute humidity return process A3). And exhaust air of exhaust air absolute humidity Ha which is below the saturated water vapor pressure and close to the saturated water vapor pressure is supplied to such an extent that the inside of the grain flow passage 13 does not condense beyond the saturated water vapor pressure.

  When close to the finishing moisture value, the first control valve 23 and the second control valve 22 adjust and control to increase the rate at which the exhaust air is sequentially discharged outside the machine, thereby gradually reducing the grain temperature and reaching the set moisture. Thus, the hulling process after finishing the drying operation can be performed quickly (finishing discharge process A4).

Here, with the example of the grain, the drying theory, that is, giving moisture and heat to the grain will be described with reference to FIG.
In the conventional drying control, as shown in FIG. 11 (A), when the amount of drying heat generated by the combustion burner 5 and supplied to the kernel is 100, the moisture in the kernel is mainly in the initial stage of drying. It is consumed by the heat of vaporization, which is the amount of heat to be evaporated (for example, 95), and the rest is used for increasing the grain temperature. That is, since the moisture value of the grain is high at the initial stage of drying, most of the supplied heat is used for vaporization of moisture. Therefore, simply increasing the amount of drying heat promotes drying on the grain surface side from the inside of the grain, and on the contrary, the moisture gradient in the grain becomes high and it becomes easy to crack the trunk.

  On the other hand, with respect to the drying control of the present embodiment, as shown in FIG. 11 (B), by returning the exhaust air at the initial stage of drying and generating dry hot air of a predetermined condition, it is difficult to crack the body at high speed. It is what makes it possible. That is, assuming that the amount of heat generated in the combustion burner 5 is 100, and the amount of heat of the exhaust air contained in the exhaust air is added to the amount of heat of the dry hot air, the total amount of heat that the exhaust air merges with the dry hot air is 150. . Here, it has been found that the new dry air condition is that the absolute humidity is close to and below the saturated water vapor pressure.

  And when a new dry wind acts on the grain, the moisture in the grain given the heat is going to vaporize from the grain surface, while the absolute humidity is near the saturated water vapor pressure and the saturated water vapor pressure as described above. By adjusting to the following, moisture detection from the grain surface is suppressed, and the amount of heat applied acts on the inside of the grain, for example, the amount of heat used for the heat of vaporization becomes 60 lower than the conventional 95, which increases the grain temperature. The amount of heat used is 90. Therefore, although the grain temperature rises rapidly, the moisture transfer in the grain is promoted, the moisture gradient does not rise rapidly, and the shell cracking hardly occurs.

  And since the amount of exhaust air of return exhaust air can be adjusted according to the moisture value of the grain detected during drying, a humidity sensor or the like for detecting the humidity of exhaust air is not required, and the cost is not increased. Moreover, it is possible to dry while giving appropriate moisture to the object to be dried, that is, moisture enough to keep the grain flow passage 13 below the saturated water vapor pressure and close to the saturated water vapor pressure.

  It has been found that the new dry air condition described above can be obtained by merging the dry hot air and the exhaust air by the combustion burner 5. That is, the dry wind acting on the grain absorbs moisture and is discharged as exhaust air, but the exhaust air return amount is adjusted by paying attention to the absolute humidity of the exhaust air.

  Here, as shown in the graph of FIG. 10, it has been found by tests that the exhaust wind absolute humidity substantially corresponds to the moisture value of the grain. That is, the higher the moisture value of the grain, the higher the exhaust wind absolute humidity. This is because the water vapor pressure to be vaporized from the surface of the grain is high, so that much exhaust air humidity is required to suppress it, and the drying operation proceeds and the grain moisture value decreases. This is because the amount of water vaporized from the grain decreases, and the amount of water for suppressing the moisture in the grain is at least improved. In the present embodiment, the graph of FIG. 10 is stored in the storage unit ME of the control unit F, and the required exhaust air absolute humidity value is derived based on the detected moisture value data.

  If saturated steam is exceeded, condensation may cause the grain to be steamed and quality may be impaired, but to the extent that it does not exceed it, heat and moisture contained in the exhaust air are given to the grain, so much heat inside the grain. In addition, the moisture that is going to evaporate from the surface of the grain is suppressed inside the grain object by the moisture in the exhaust air. When heat is supplied to the inside of the grain, the surface moisture side transition is promoted, so that the moisture gradient inside the grain can be reduced and the inside of the grain is cracked while being dried at high speed. It can be made difficult to wake up.

Next, an example of control for adjusting the opening of the control valve will be described using representative numerical values.
The outside air temperature detected by the outside air temperature sensor TA is 20 ° C., the outside air humidity detected by the outside air humidity sensor TH is 70%, and the absolute humidity (Z) calculated by the control unit F is 13 g / m 3. Then, it is assumed that the absolute humidity (U) of the exhaust air (Y) as a control target set corresponding to the grain moisture value detected by the moisture meter 10 in FIG. 10 is 25 g / m 3. And the air volume of the exhaust fan 7 of a present Example is 1900 kg / h, the quantity of the grain (rice cake) supplied to the grain dryer is 800 kg, and the drying rate (it is dried per hour) which shows a drying rate. When the ratio of moisture) is 1.2% / h, how much of the exhaust air is returned to the hot air chamber 13 is obtained from the following equation.

Absolute humidity (U)-Absolute humidity (Z) = 12 (g / m3) ... B1
The maximum amount of water that can be absorbed by outside air is 12 x 1900/1000 ≒ 23 (kg) ... B2
And the amount of water removed from the grain per hour is 800 (kg) × 1.2 (% / h) = 9.6 (kg / h)... B3
From the formula of B2 and the formula of B3, 23 / (9.6 + 23) ≈0.71 → 71%... B4
In other words, the control valve drive motor 25 is controlled to adjust the first control valve 23 and the second control valve 22 so that 71% of the exhausted air discharged from the exhaust fan 7 is returned to the hot air chamber 11.
That is, the rotation angle θ of the first control valve 23 corresponding to the return rate of the exhaust air is stored in the storage unit ME in advance, and the control valve drive motor 25 corresponds to the exhaust air rate 71% based on the calculation result. Are linked forward and backward.

  More specifically, the above-described calculation formula calculates the absolute humidity (Z) of the outside air by a control unit (not shown) from the temperature and humidity of the outside air detected by the outside temperature sensor TA and the outside air humidity sensor HA, respectively. The difference between the absolute humidity (Z) of the outside air and the absolute humidity (U) of the exhaust wind set in advance from the condition of the grain moisture detected by the moisture meter 10 is the maximum water absorption amount that the outside air can absorb. Calculate (Equation B1 and Equation B2). On the other hand, the amount of water evaporated from the grain by the drying operation (the amount of water removed from the grain per hour in the present embodiment) is obtained (formula B3), and the amount of increased water is the amount of water evaporated by the drying operation. The ratio to the sum of the values is considered as the ratio for returning the wind.

That is, the formula B4 is the amount of increased water / (the amount of water evaporated from the grain + the increased amount of water).
Is shown. This formula is particularly effective for a dryer that continuously performs a drying action on an object to be dried.

  However, in this embodiment, in the grain dryer that alternately circulates the grain through the storage unit 2 and the drying unit 3 and alternately performs the drying action and the tempering action (so-called tempering), the grain is dried as described above. When the grain which supplied heat and moisture in the part is circulated to the storage part 2, when there is too much heat and moisture to be supplied, drying from the grain surface proceeds from the transfer of moisture inside the grain, Grain shell cracking may increase.

Therefore, particularly in the case of a grain dryer, the drying control may be performed based on the following formula B5 instead of the formula B4.
Increased amount of water / (amount of water evaporating from cereal + absolute humidity of exhaust air (U)) ... B5
23 / (9.6 + 47.5) ≈0.42 That is, 42% exhaust air is returned.

Note that 47.5 (kg) is calculated from 25 g / m 3 of the absolute humidity (U) described above and the air volume of the exhaust fan 1900 kg / h.
47.5 = 25 × 1900/1000 ... B6
In the circulation type dryer that performs drying by the tempering method, in order to suppress the surface drying while stopping in the storage unit 2, the absolute airflow that is set by the absolute humidity that passes through the storage unit 2 is set in Formula B5. Change and correct the total amount of water that the wind that passes through the grain per unit time has so that it becomes humidity.

  In addition, when the 1st control valve 23 and the 2nd control valve 22 are adjusted so that more than 71% of the amount of exhausted air may be returned to the hot air chamber 11, the more water is returned, the more water is returned. It becomes difficult to remove moisture from the grain. In addition, when the first control valve 23 and the second control valve 22 return an amount smaller than 71% of the exhausted air amount to the hot air chamber 11, the amount of heat returned to the hot air chamber 11 decreases, so that the temperature of the grain rises. It becomes difficult to peel off and the drying speed becomes slow.

  By adjusting the ratio of returning the exhaust air from the equation of the present embodiment, the drying operation with good combustion efficiency can be performed by appropriately using the heat generated by the exhaust air discharged from the exhaust air fan 6, that is, the water absorption force as much as possible. It can be performed.

FIG. 12 is a diagram illustrating correction of the ratio of returning the exhaust air set based on the grain moisture value and exhaust air absolute humidity based on FIG. 10 described above.
The outside temperature and the amount of grain filling are shown as conditions for correction. That is, it correct | amends so that the ratio which returns exhaust air may be reduced, so that external temperature is high. Curves M1, M2, M3, M4, and M5 indicate correction of the exhaust wind return rate for each amount of tension, and the correction is performed so that the ratio of returning the exhaust wind is reduced as the amount of tension increases.

  Since the drying of the grain is promoted as the outside air temperature becomes higher, it is possible to reduce the amount to return the exhaust air accordingly. Moreover, since the grain temperature which rises most is so high that there is much tension | tensile_strength, the amount which returns exhaust air by that amount can be reduced.

  In the above-described embodiment, the description has been given as means for deriving the return ratio with respect to the total exhaust air amount as the exhaust air return amount. However, the exhaust air return amount may be stored in the storage unit and the exhaust air return amount may be controlled.

In this embodiment, the drying rate indicating the drying rate is 1.2%, but the rate of returning the exhaust air is changed depending on the drying rate.
In this embodiment, the absolute humidity of the outside air is obtained from the outside air humidity sensor HA, but instead of the outside air humidity sensor, the absolute humidity of the outside air based on the outside air temperature reference may be determined and used as a substitute value.

  In this embodiment, a grain dryer for straw, wheat, beans, etc. has been described, but in addition to this, it has been collected from nature such as shiitake mushrooms, timber and marine products, and moisture is applied to the surface portion and the inner central portion of the dried object. The present invention can also be used in the case of a dryer that uses an object with a gradient as an object to be dried.

The perspective view explaining the inside of the whole grain dryer The perspective view explaining the structure of a drying part and a grain collection part Front view illustrating the configuration of the drying unit and the cereal collecting unit Side view and rear view of exhaust fan for explaining interlocking configuration of first control valve and second control valve A perspective view showing an exhaust air supply duct, an exhaust air distribution case, and an exhaust fan The perspective view explaining the inside of a burner case and a heat exhaust air passage case Side view explaining the inside of the burner case The perspective view explaining the inside of a burner case Graph showing the relationship between drying process and grain temperature Diagram showing the relationship between absolute wind humidity and grain moisture value Diagram explaining the heat supplied to the grain The figure which shows changing the ratio which recirculates the exhaust wind with outside air temperature and tension amount Block Diagram

DESCRIPTION OF SYMBOLS 1 Main body 5 Combustion burner 5a Combustion disc surface 6 of combustion burner Exhaust fan 11 Hot air chamber 13 Grain flow passage 20 Exhaust duct 22 Second adjustment plate 23 First adjustment plate 23a Rotating shaft 24 Rod 44 Second return passage k Combustion Burner surface position e 5th exhaust opening Q Combustion flame

Claims (4)

A drying section for drying the grain by applying hot air for drying;
A return means for merging the exhaust air after passing through the grains with the hot air for drying,
The combined air of the hot air for drying and the return exhaust air acting on the grain supplies the return exhaust air near the saturated water vapor pressure and does not exceed the saturated water vapor pressure ,
Store the correspondence relationship between the absolute wind humidity and the grain moisture value in the storage unit of the control unit in advance,
A grain drying method in which the amount of return exhaust air is controlled based on the grain moisture value detected during drying . The grain drying method according to claim 1 , wherein the amount of return exhaust air set from the relationship between the absolute wind exhaust humidity and the moisture value of the grain is corrected by increasing or decreasing the amount of tension . The grain drying method according to claim 1, wherein the return wind volume set based on the relationship between the absolute wind humidity and the moisture value of the grain is corrected by the level of the outside air temperature . 2. The grain drying method according to claim 1, wherein the amount of return wind set based on the relationship between the absolute wind humidity and the moisture value of the grain is corrected by the drying speed .

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