JP2878085B2 - Dryer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dryer for use in the production of shredded radish and the like. More specifically, the present invention relates to a supply / exhaust means for ventilating drying air into a storage chamber for storing objects to be dried, Weight detection means for detecting the weight of the object,
Finished weight setting means for setting a target finished weight, which is a predicted weight of the object to be dried when dried to a target moisture content, a weight detected by the weight detecting means, and a drying process based on the target finished weight. And a stop command means for giving a stop command.

[0002]

2. Description of the Related Art Conventionally, in a drier as described above, an operator empirically determines the predicted weight (target finished weight mW) of an object to be dried when it is dried to a target moisture content mα. In contrast to setting the finished weight mW by the finished weight setting means, the stop command means simply outputs the weight W of the drying object detected by the weight detecting means.
Is reduced to the target finished weight mW, a command to stop the drying process is given. In other words,
Based only on the comparison between the target finished weight mW artificially set based on experience and the weight W detected by the weight detecting means,
The mode in which the point at which the drying process should be stopped was determined was adopted.

[0003]

However, in the conventional dryer, the target finished weight mW set as described above has a certain degree of difference from the true finished weight sW of the object to be dried dried to the target moisture content mα. At the time when the stop command is given by the stop command means (that is, when the detected weight W is reduced to the target finished weight mW), the water content α of the object to be dried is still the desired target water content mα. That the object to be dried is in a state of insufficient drying, or conversely, when a stop command is given by the stop command means, the moisture content α of the object to be dried is already at the desired target. Significantly lower than the water content mα,
The object to be dried was over-dried.

That is, in an error mode in which the target finished weight mW is set to be too large with respect to the true finished weight sW, the time at which the stop command is given by the stop command means is earlier than the appropriate time by the error, and the drying is insufficient. On the other hand, in the error mode in which the target finished weight mW is set to be too small with respect to the true finished weight sW, the over-drying is performed by delaying the time at which the stop command is given by the stop command means from the appropriate time at which the stop command is given. Was to be invited. Insufficient drying can be dealt with by performing replenishment drying treatment again, but not overdrying, which results in a large decrease in finished quality due to overdrying and a decrease in product quantity. Had a problem.

[0005] An object of the present invention is to give an instruction to stop the drying process with a rational determination of the drying state, thereby preventing overdrying due to the target finished weight being erroneously set to be smaller than the true finished weight. In addition to ensuring prevention, it is possible to effectively suppress the occurrence of insufficient drying.

[0006]

The feature of the dryer according to the present invention is that the air supply / exhaust means for ventilating the drying air through a storage chamber for storing the drying object and the weight of the drying object in the storage chamber are detected. Weight detecting means, a finished weight setting means for setting a target finished weight that is a predicted weight of the object to be dried when dried to the target moisture content, a weight detected by the weight detecting means, and the target finish In a configuration in which stop command means for giving a stop command for drying processing based on weight is provided, a temperature difference detecting means for detecting a difference between supply and exhaust temperatures of the storage chamber is provided, and the stop command means includes the following (A) to (B). D) calculating the rate of decrease in the supply / exhaust temperature difference detected by the temperature difference selecting means during the drying process; and (b) calculating the weight detected by the weight detecting means from the target finished weight. The time when the check weight is reduced to the check weight larger by the predetermined ratio is set as the check point, and based on the change in the decreasing speed gradient up to the check point, the stop command giving control is performed in the differential temperature reference mode or in the weight reference mode. (C) When the differential temperature reference mode is selected, the drying / supply / exhaust temperature difference reduction limit at which the drying process should be stopped according to the detected supply / exhaust temperature difference of the differential temperature detecting means at the time of the check. Determine the value, and
When the difference between the detected supply and exhaust temperatures by the temperature difference detection means has reached the determined decrease limit value, a command to stop the drying process is given.
(D) When the weight reference mode is selected, a command to stop the drying process is given when the weight detected by the weight detecting means reaches the target finished weight.

[0007]

In other words, in a mode in which the drying object is dried in the storage room by passing the drying air through the storage room, as the drying progresses and the water content α of the drying object decreases, the moisture evaporates from the drying object. The amount of vaporized heat withdrawn from the drying air decreases, and the difference between the supply and exhaust air temperature Δt (= ti-to, where ti: drying air supplied to the storage room) Temperature, to: the temperature of the drying air exhausted from the storage chamber) also decreases as the water content α decreases as its basic change characteristic. Further, as a result of further study on the relationship between the water content α and the supply / exhaust temperature difference Δt (hereinafter, simply referred to as the temperature difference), there is generally the following correlation between the water content α and the temperature difference Δt. It has been found.

That is, FIG. 5 shows, as an example, the water content α and the differential temperature Δ in the shredded radish production process in which radish is to be dried.
The solid line in the figure indicates the amount of radish as the object to be dried, the installation state in the storage room, or
Experimental results in the case where operating conditions such as outdoor temperature and humidity are varied are shown. As can be seen from FIG. 5, in general, the temperature difference Δt for each value of the water content α is equal to the operating conditions as described above. Some variation due to the difference (for example, in the example of FIG. 5, the temperature difference Δt for the water content α = 34% is 1.8 to 3.
Although there is a variation of 1 ° C.), the variation of the temperature difference Δt has an upper limit (shown by a dashed line in H) and a lower limit (shown by a dashed line in L).
, The upper and lower limits of the variation of the temperature difference Δt both decrease while the variation width decreases.

In other words, the water content α for each value of the temperature difference Δt has some variation due to the difference in the operating conditions, but the variation in the water content α is a lower limit (corresponding to the dashed-dotted line H). There is an upper limit (corresponding to the dashed-dotted line of L), and as the drying proceeds and the temperature difference Δt decreases,
The water content α decreases with a decrease in the variation width.

Therefore, if a specific correlation between the water content α and the temperature difference Δt of a specific drying object is quantitatively grasped in advance based on experiments and the like (see FIG. 6),
Even if there is a possibility that the target finished weight mW may be erroneously set, at an appropriate check point before the weight W of the drying target reaches the target finished weight mW, the temperature difference Δt at the check point and the target water content mα By comparing the variation range of the temperature difference mD with the temperature difference range mD (in other words, comparing the variation range of the water content α with the difference temperature Δt at the check time and the target moisture content mα), the following determination can be made for the water content α. .

As a result of the above comparison, the temperature difference Δ
When t is larger than the upper limit of the difference temperature variation range mD with respect to the target water content mα (for example, when the temperature difference Δt = Δt1 at the time of the check in FIG. 6), the water content α at the time of the check is changed to the target water content mα. It is still possible to determine that the water content α is still larger than the target temperature until the temperature difference Δt reaches the upper limit of the temperature difference variation range mD with respect to the target water content mα even if the drying process is further performed from the time of the check. It can be determined that the water content does not become smaller than mα.

As a result of the comparison, when the temperature difference Δt at the time of the check is within the range of the temperature difference variation mD relative to the target water content mα (for example, in FIG.
(when t = Δt2), it can be determined that the moisture content α may already be equal to or less than the target moisture content mα at the time of the check.

As a result of the comparison, the temperature difference Δ
When t is equal to or less than the lower limit of the temperature difference variation range mD with respect to the target moisture content mα, it can be determined that the moisture content α has already reliably reached the target moisture content mα at the time of the check.

In general, the target water content m α has a certain allowable range around the target water content m α, so that the target water content m α at the appropriate check point as described above. By comparing the difference temperature variation range m D "with respect to the allowable range lower limit m α" and the difference temperature Δt at the time of the check, the following determination can be made in the same manner as described above (FIG. 6).
reference).

As a result of the comparison, when the temperature difference Δt at the time of the check is larger than the upper limit of the temperature difference variation range mD ″ with respect to the allowable range lower limit mα ″ of the target moisture content mα (for example, in FIG. Δt3)
Even if the water content α at the time of the check is lower than the target water content mα, it can be determined that the water content is still larger than the allowable lower limit mα ”of the target water content mα, and the drying process is further performed from the time of the check. But the temperature difference Δt
Until the target water content mα reaches the upper limit of the temperature difference variation range mD ″ with respect to the allowable range lower limit mα ″, it can be determined that the water content α does not become smaller than the allowable range lower limit mα ″ of the target water content mα.

As a result of the comparison, when the temperature difference Δt at the time of the check is within the range mD ″ of variation in the temperature difference with respect to the allowable lower limit mα ″ of the target moisture content mα (for example, in FIG. At the time of Δt2), it can be determined that the water content α at the time of the check may already be equal to or less than the lower limit mα ″ of the allowable range of the target water content mα.
When t is equal to or smaller than the lower limit of the temperature difference variation range mD ″ with respect to the allowable lower limit mα ″ of the target water content mα, the water content α is surely already at the check time.
It can be determined that α is less than or equal to the allowable lower limit mα ″.

On the other hand, a weight cW (= mW + k × mW /) which is larger than the target finished weight mW by a predetermined ratio k%.
If the point at which the detected weight W of the object to be dried W decreases to the check weight cW is the check point, the target finished weight mW is smaller than the true finished weight by k% or less. In the setting (erroneous setting on the overdrying side), the temperature difference Δt at the time of the check when the detected weight W becomes the check weight cW falls within the range or the lower limit of the temperature difference variation range mD with respect to the target moisture content mα. Even if (that is, in the determination based on the temperature difference Δt at the time of the check, the moisture content α is already the target moisture content m
even if it is less than α), the error of the target finished weight mW to the underside is less than k%, and the check weight cW is still larger than the true finished weight. The water content α is not actually smaller than the target water content mα.

That is, in a situation where the target finished weight mW is correctly set to the true finished weight sW, FIG.
The position a corresponding to the target moisture content mα in the abscissa direction is the position corresponding to the true finished weight sW, and
The position corresponding to the correctly set target finished weight mW, and the position b on the high moisture content side by k% weight from that position is the position of the check weight cW with respect to the correctly set target finished weight mW, that is, the position at the time of the check. Becomes

However, the target finished weight mW is k
%, The target water content mα in the horizontal axis direction in FIG. 4 is incorrectly set to be smaller than the true finished weight sW.
Is a position corresponding to the true finished weight sW, while a position corresponding to the erroneously set target finished weight mW is a position c on the low water content side by k% weight.
Therefore, the position a corresponding to the target moisture content mα is the check weight c with respect to the erroneously set target finish weight mW.
W and the position at the time of checking.

If the error in incorrectly setting the target finished weight mW smaller than the true finished weight sW is less than the above-mentioned k%, the position of the check weight cW, that is, the position at the time of the check, is equal to the target. The position b at the time of the check when the finished weight mW is correctly set to the true finished weight sW, and the position a at the time of the check when the target finished weight mW is erroneously set by k% smaller than the true finished weight sW. Will be located between

Therefore, in an erroneous setting in which the target finished weight mW is set smaller than the true finished weight sW,
As long as the error is not more than k% of the target finished weight mW, the temperature difference Δt at the time of the check when the detected weight W becomes the check weight cW is within or within the range of the temperature difference variation range mD with respect to the target water content mα. In the determination based on the temperature difference Δt at the time of the check, the error of the target finished weight mW toward the underside is k% or less even if the water content α may already be equal to or less than the target moisture content mα. Since the check weight cW is still larger than the true finished weight sW, the water content α at the time of the check does not actually become smaller than the target water content mα.

In other words, when setting the target finished weight mW, if there is a possibility that the target finished weight mW may be erroneously set smaller than the true finished weight sW up to the maximum k% of the target finished weight mW, If the value of k% as the maximum possible error is used as the predetermined ratio that determines the cW and the check time, even if the target finished weight mW is incorrectly set, the detected weight W is reduced. It is possible to reliably avoid that the water content α has already become smaller than the target water content mα at the time of the check at which the check weight cW is reached.

Since the target moisture content crack at the time of the check can be reliably prevented as described above, when the temperature difference Δt is within the range of the temperature difference variation range mD with respect to the target water content mα or at the lower limit at the time of the check ( In particular, even when the difference is within the upper limit of the difference temperature variation range mD ″ with respect to the allowable lower limit mα ″ of the target moisture content mα and is equal to or greater than the lower limit of the difference temperature variation range mD with respect to the target moisture content mα), As long as the temperature difference is reduced to the extent that the water content decreases from the water content α to its allowable range lower limit mα ″, even if the drying process is further advanced from the time of the check to reduce the temperature difference Δt, the water content α is the target. It can be determined that the water content mα will not be smaller than the allowable lower limit mα ″.

In short, in a form in which the time when the detected weight W decreases to the check weight cW which is larger than the target finished weight mW by a predetermined ratio is set as the check time, the check weight cW and the predetermined ratio which determines the check time are appropriate. Is adopted, the water content α becomes the target water content m.
Even if the target finished weight mW is erroneously set to be smaller than the true finished weight sW that is α and the error is uncertain, as long as it is within the expected normal error range,
When the check point is reached, the water content α has already reached the target water content m
At the time of the check, while reliably avoiding that the temperature difference is smaller than α, the reduction limit value mΔt of the temperature difference Δt at which the temperature difference Δt can be finally reduced, that is, the target moisture content mα, or the lower limit value mΔt of the temperature difference Δt, which is an index of how much the water content α can be finally reduced within a range where the possibility of becoming smaller than the allowable lower limit mα ″ does not occur. The detected temperature difference Δt at the time of the check is determined by various determination modes such as
Can be determined according to

Accordingly, as one of the control modes for giving a command to stop the drying process, the reduction limit value mΔt of the differential temperature Δt is determined in accordance with the detected differential temperature Δt at the time of the check as described above. If a control mode based on the temperature difference is adopted, in which a stop command is given when the reduction limit value mΔt is reached, regardless of whether the target finished weight mW is erroneously set to be smaller than the true finished weight sW. A stop command is given when the water content α approaches the target water content mα as much as possible while avoiding overdrying in which the water content α falls below the target water content mα or the allowable lower limit mα ″. be able to.

On the other hand, in the control mode based on the differential temperature as described above, if the differential temperature Δt at the check time is equal, the same differential temperature reduction limit value mΔt is obtained regardless of the displacement at the check time due to an error in the target finished weight mW. The state at the time of the check in FIG.
x, the target finish weight mW is incorrectly set to be smaller than the true finish weight sW, and the corresponding position of the target finish weight mW is lower than the corresponding position a of the target moisture content mα on the water content side. (X position) and the case where the state at the time of the check in FIG. 7 is given by the point Py, the target finished weight mW is incorrectly set to be larger than the true finished weight sW. In the case where the corresponding position of the target finished weight mW is located on the higher moisture content side than the corresponding position a of the target moisture content mα (y position), the positions at the check points are different from each other, but the temperature difference Δt at those check points is different. Equivalent (Δt = Δt4)
As a result, it is possible that the same temperature difference limit value mΔt is determined and adopted.

From the above, if the above-mentioned differential temperature reference mode is simply adopted in the control for giving the stop command,
Compared to the weight-based control mode in which a stop command is given when the detected weight W reaches the target finished weight mW,
In the case where the target finished weight mW is erroneously set to be larger than the true finished weight sW, the temperature difference Δt at a point earlier (ie, on the high water content side) than when the detected weight W reaches the target finished weight mW (y position). Is the decision reduction limit value mΔt
And dry shortage may be promoted.

In this regard, the water content α and the temperature difference Δt
(See FIG. 5), the characteristic that the temperature difference Δt has a portion where the decreasing gradient of the temperature difference Δt sharply increases when the drying process proceeds and the water content α decreases to a certain extent. Reflecting this, the decreasing speed gradient V = dΔt / dh of the temperature difference Δt, that is, the decreasing amount of the temperature difference Δt per unit time, is also determined when the drying process proceeds and the water content α decreases to some extent. The decreasing speed gradient V
Is rapidly increased.

Therefore, if the change in the differential temperature decreasing rate gradient V up to the check point is monitored, the corresponding position at the check point is already at the corresponding position a of the target water content mα at the check point based on the change form. Judgment as to whether it is approaching or is still far from the corresponding position a of the target moisture content mα, that is, the corresponding position b at the time of checking when the target finished weight mW is correctly set to the true finished weight sW Compared to the situation, the check point is on the low water content side and the target finished weight mW is incorrectly set to the lower side, or the check point is on the high water content side and the target finished weight mW is incorrectly set on the excessive side. It is possible to determine whether the situation is set.

When it is determined that the target finished weight mW is erroneously set to an underside in the determination based on the change in the differential temperature decreasing speed gradient V up to the check point, a stop command is issued. By employing the above-described differential temperature reference mode in the application control, the occurrence of overdrying can be reliably prevented. On the other hand, when it is determined that the target finished weight mW is erroneously set to the excessive side, the detected weight By adopting the weight reference mode in which a stop command is given when W reaches the target finished weight mW, it is possible to avoid the promotion of insufficient drying as described above, and the target finished weight mW is a true finish. In a situation where the weight sW is correctly set, the water content α
Can accurately improve that a stop command is correctly given when the target water content mα is reached.

[0031]

According to the features of the present invention,
In spite of the fact that the target finished weight may be incorrectly set to be smaller than the true finished weight, it is possible to reliably avoid overdrying, which can lead to unmanageable quality deterioration and loss of product quantity. If the finished weight is incorrectly set to be larger than the true finished weight, it is possible to prevent the lack of drying from being promoted. The replenishment drying process can be performed easily and accurately because the degree of shortage is slight, and it stops properly when the water content reaches the target water content when the target finished weight is set correctly. Since the accuracy of giving a command can be improved, a high finish quality can be stably and simply secured with an appropriate quantity as a whole.

[0032]

Next, an embodiment will be described.

FIG. 1 shows the structure of a drying machine. 1 is a truck for loading and drying objects X (raw material of shredded radish etc.) in upper and lower stages, and 2 is a two trucks on which drying objects X are placed. 1 is a storage room in which one is arranged side by side on one side of the room and the other side.
Numeral 3 denotes a fan for ventilation drying as a supply / exhaust means, which can be switched between normal and reverse rotations. When the fan 3 is operated in normal rotation, the storage chamber 2 moves from one side to the other side as shown by the solid line arrow in the figure. The drying air A is passed from the other side of the storage chamber 2 to one side as shown by a broken arrow in the drawing by passing the drying air A and performing the reverse operation.

4 and 5 are open air openings 6 and 7 in the position shown by the dashed line in the figure and the outside air closed state in which the circulation air path to the dehumidifier 8 is closed. This is a damper that switches the air path between a closed air opening state and a circulating air path state in which the openings 6 and 7 are closed and the circulation air path to the dehumidifier 8 is opened. One side (right side in the figure) of the storage room 2 by using the outside air OA taken in from the upper outside air port 6 as the drying air A by the normal operation of the fan 3.
From the outside air OA after ventilating to the other side and discharging the outside air OA to the outside from the lower outside air port 7, and the fan 3 is operated in reverse with the dampers 4 and 5 also in the outside air ventilation state. The outside air OA taken in from the lower outside air port 7 is used as the drying air A as the other side of the storage chamber 2 (left side in the figure).
And the outside air OA after the ventilation is automatically alternately performed with the outside air ventilation reverse operation of discharging the outside air OA after the ventilation to the outside from the upper outside air port 6, thereby drying the drying object X in the room with the outside air OA. Dry.

In a situation where the drying process cannot be performed by the ventilation of the outside air OA, the fan 3 is operated in the forward direction with the dampers 4 and 5 circulating and the air dehumidified by the dehumidifier 8 is stored as the drying air A. Circulating ventilation normal rotation operation in which air is ventilated from one side (right side in the figure) of the chamber 2 to the other side and the air after ventilation is returned to the dehumidifier 8, and the fan 3 is similarly operated in reverse with the dampers 4 and 5 in the circulating ventilation state. As a result, the air dehumidified by the dehumidifier 8 is used as drying air A on the other side of the storage chamber 2 (left side in the figure).
And the circulation ventilation reverse operation of returning the air after ventilation to the dehumidifier 8 is automatically and alternately performed, whereby the drying object X in the room is forcibly dried by the dehumidifier 8. .

The dehumidifier 8 includes an indoor evaporator 8a for cooling and dehumidifying the air returning from the storage chamber 2, an indoor condenser 8b for reheating the cooled and dehumidified air, and an outdoor condenser for radiating the outside air OA. The heat pump includes a heat pump provided with a heat exchanger 8c, and the operation mode includes a heating and dehumidifying mode in which the entire amount of refrigerant condensation is performed in the indoor condenser 8b to increase the reheat amount, and a part of the refrigerant condensation in the outdoor condenser. And a cooling / dehumidifying mode in which the amount of reheating by the indoor condenser 8b is reduced, and stored in a set temperature range (trm ± dt) centered on a set room temperature trm. Room 2 room temperature tr
, The operation mode is automatically switched between the heating and dehumidifying mode and the cooling and dehumidifying mode based on the detection of the room temperature of the storage room 2.

The detection of the room temperature of the storage chamber 2 is performed as a temperature sensor.
i, and a first temperature sensor S1 for detecting the ventilation temperature t1 at one end of the storage chamber, which is the exhaust temperature to from the storage chamber 2 at the time of the fan reverse operation, and conversely, the storage at the time of the fan normal operation. A second temperature sensor S2 for detecting a ventilation temperature t2 at the other end of the storage chamber at which the exhaust temperature from the chamber 2 becomes to and the supply air temperature ti to the storage chamber 2 during the reverse operation of the fan; Temperature t detected by each of first temperature sensor S1 and second temperature sensor S2
1, the average temperature of t2 is detected by the storage room 2 at room temperature tr (= (t
1 + t2) / 2).

Reference numeral 9 denotes a control device for automatically switching between the heating dehumidification mode and the cooling dehumidification mode, automatically switching between the fan normal operation and the fan reverse operation, and automatically stopping the drying process. As shown in FIG. 2, when the detected room temperature tr (= (t1 + t2) / 2) falls to the lower limit value trm-dt of the set temperature range (trm ± dt), as shown in FIG. When the operation mode is switched to the heating dehumidification mode, and the detected room temperature tr (= (t1 + t2) / 2) rises to the upper limit value trm + dt of the set temperature range (trm ± dt), the operation mode is switched to the cooling dehumidification mode. There is.

For automatic switching between the fan normal operation and the fan reverse operation, the drying object X on the truck 1 closer to one side of the room and the drying object X on the truck 1 closer to the other side of the room are respectively: Irrespective of the difference in weight and the difference in the initial moisture content, one-side drying in a trial fan normal rotation operation at the beginning of the drying process is performed so that the weight is reduced to the check weight cW described below in the same drying process time. The amount of weight loss per unit time of the object X, the amount of weight reduction per unit time of the object X to be dried on the other side in the test fan reversal operation at the beginning of the drying process, and the test fan operation The weight W and the check weight c of each of the later dried objects X
A predetermined forward / reverse rotation period T based on the difference from W (W−cW)
(For example, 100 minutes), the normal rotation operation time T1 and the reverse rotation operation time T2 (= T−T1) are determined, and after the test fan operation at the beginning of the drying process, both the drying objects X have the check weight cW. Until the normal rotation operation time T
The configuration is such that the fan normal rotation operation of 1 and the fan reverse rotation operation of the reverse rotation operation time T2 are alternately repeated.

In FIG. 2, the point at which the level relationship between the detected temperature t1 of the first temperature sensor S1 and the detected temperature t2 of the second temperature sensor S2 reverses is the point in time when switching between the fan normal operation and the fan reverse operation. Corresponding. Also, since FIG. 2 shows experimental data, there are some disturbances in data values due to various disturbances.

On the other hand, as for the automatic stop of the drying process, a weight sensor using a load cell as a weight detecting means for detecting the weight W of the drying object X on one side and the weight W of the drying object X on the other side. 10 is provided on each of the carts 1, and the target finish which is the predicted weight when the drying object X is dried to the target moisture content mα for each of the one-side drying object X and the other-side drying object X. Weight mW,
A setting device 11 is provided as finished weight setting means for the operator to determine and set each drying object X from the initial state.

The control unit 9 is configured to perform the following control operations on the information from the weight sensor 10 and the setting device 11 (see FIG. 3).

The weight (mW + k × mW / 100) that is larger by a predetermined ratio k% than the target finished weight mW set by the setting unit 11 for each of the one-side drying target X and the other-side drying target X. Check weight cW. In the present example, the target finish weight mW may be erroneously set to ± 10% as the maximum error with respect to the true finish weight sW at which the drying target X has the target moisture content mα. A specific numerical value of 10% is adopted as the predetermined ratio k% for determining the check weight cW.

The temperature t detected by the first temperature sensor S 1
1 and the temperature t1 detected by the second temperature sensor S2, that is, the difference between the supply and exhaust temperatures of the storage chamber 2 (difference temperature Δt = ti−t).
o) is monitored, and each of the differential temperature measurement, the differential temperature measurement value Δtn stored during the previous differential temperature measurement, and the elapsed time hn from the first differential temperature measurement are denoted by Δtn−1 and hn−1. And the new measured value of the differential temperature and the elapsed time from the first differential temperature measurement are stored as Δtn and hn.

Further, each time the temperature difference is measured, the rate of decrease of the temperature difference Δt, V = dΔt / dh, is the average rate of decrease of the temperature Vn−1 from the time of the first measurement of the differential temperature to the time of the previous measurement.
The decreasing speed gradient Vn0 in the latest measurement period and the determination threshold Vm are calculated by the following equation. Vn-1 = (. DELTA.ts-.DELTA.tn-1) / hn-1 (.DELTA.ts is the first measured value of the differential temperature) Vn0 = (. DELTA.tn-1-.DELTA.tn) / (hn-hn-1) Vm = r.times. (Vn-1 (Where r is one or more suitable coefficients, for example r = 3.5)

Then, the reduction speed gradient Vn0 in the latest measurement period as the calculation result is compared with the determination threshold Vm, and the reduction speed gradient Vn0 in the latest measurement period is equal to or larger than the determination threshold Vm (Vn0 ≧ Vm = r × (Vn-1)), that fact is stored.

That is, the fact that the decreasing speed gradient Vn0 in the latest measurement period is equal to or larger than the determination threshold value Vm is as follows.
Rate difference gradient K = dΔt / d with progress of drying process
As a change in h, it indicates that the decreasing speed gradient K sharply increased from the average value up to that time.

The temperature difference Δt of the storage chamber 2 (= ti-to,
(Δt = t1−t2 in the fan normal rotation operation and Δt = t2−t1 in the fan reverse rotation operation) show a peak value when the mode is switched from the heating dehumidification mode to the cooling dehumidification mode. As the temperature difference Δt at the time of switching from the heating dehumidification mode to the cooling dehumidification mode.
Is used as a control index of the drying process stop control. In accordance with this, the above-described differential temperature measurement is performed when switching from the heating dehumidification mode to the cooling dehumidification mode.

The time when the detected weight W of the drying object X closer to one side, that is, the drying object X which is the windward side in the normal rotation operation of the fan is reduced to the check weight cW, is referred to as a check point. The alternate switching between the heating dehumidifying mode and the cooling dehumidifying mode, and the alternate switching between the fan normal rotation operation and the fan reverse rotation operation are performed in a switching mode for stop timing determination. And
As a switching mode for the stop timing determination (see FIG. 2), the heating dehumidifying mode is executed by the fan normal operation until the detected room temperature tr rises to the upper limit value trm + dt of the set temperature range, and the detected room temperature tr Is alternately repeated to execute the cooling and dehumidifying mode by the fan reverse operation until the temperature decreases to the lower limit value trm-dt of the set temperature range.

That is, in the relationship between the water content α and the temperature difference Δt, the temperature difference Δt for each value of the water content α has some variation due to the difference in the operating conditions. There is a correlation that the upper limit and the lower limit exist, and that as the drying progresses and the water content α decreases, the variation of the temperature difference Δt decreases with the reduction of the variation width. , H indicates a change line at the upper limit of the differential temperature variation range, and L indicates a change line at the lower limit of the differential temperature variation range. However, in a situation where the target finished weight mW is correctly set to the true finished weight sW, , The target water content m in the horizontal axis direction in FIG.
The position a corresponding to α is a position corresponding to the true finished weight sW and a position corresponding to the correctly set target finished weight mW, and k = 10 from the position a.
The position b on the high water content side by% weight is the position corresponding to the check weight cW and the check time point with respect to the target finish weight mW of the correct setting.

The target finished weight mW is k = 10.
%, The target water content mα in the horizontal axis direction in FIG. 4 is incorrectly set to be smaller than the true finished weight sW.
Is a position corresponding to the true finished weight sW, while a position corresponding to the erroneously set target finished weight mW is a position c on the low moisture content side by k = 10% weight. Therefore, the position a corresponding to the target moisture content mα is the position corresponding to the check weight cW and the check time point with respect to the erroneously set target finish weight mW, and the target finish weight mW is higher than the true finish weight sW.
Is smaller than the above-mentioned k = 1.
If it is less than 0%, the position of the check weight cW and the corresponding position at the check point are the position b at the check point when the target finish weight mW is correctly set to the true finish weight sW and the target finish weight mW. It is located between the position a at the time of the check when the wrong setting is made smaller than the true finished weight sW by k = 10%.

Further, in a situation where the target finished weight mW is erroneously set to be larger than the true finished weight sW,
Since the position corresponding to the erroneously set target finish weight mW in the horizontal axis direction in FIG. 4 is a position on the higher moisture content side than the position a corresponding to the target moisture content mα, the check weight and the check time are accordingly changed. The corresponding position,
When the target finished weight mW is correctly set to the true finished weight sW, the target finished weight mW is located on the higher moisture content side than the position b at the time of the check.

With respect to the above-described decreasing speed gradient V of the temperature difference Δt, it is determined at the time of the check that the decreasing speed gradient Vn0 in the latest measurement period is equal to or larger than the determination threshold value Vm (Vn0 ≧ Vm = r × (Vn−1)). In the case where there is at least once in the process up to this point, the control to give the stop command is selected to be performed in the "differential temperature reference mode". If there is no such problem in the process up to the check point, it is selected that the control of giving the stop command is performed in the “weight reference mode”.

When the “differential temperature reference mode” is selected, the reduction limit value mΔt of the differential temperature Δt is determined according to the differential temperature Δt at the time of the check.

Specifically, when the dried object X is a raw material of shredded radish (see FIG. 4), the target water content mα = 20%
The variation range mD of the temperature difference Δt is 1.2 to 2.0.
° C deg, and the lower limit mα of the allowable range of the target water content mα ”
= 18% with respect to the variation range mD ″ of the temperature difference Δt is 1.
When the detected temperature difference Δt at the time of the check is 1.8 ° C. deg or more, the reduction limit value mΔt of the temperature difference Δt is set to 1.8 ° C. deg. 1.8 ° C when the detection temperature difference Δt is 1.4 ° C deg or more
When the temperature is less than deg, the reduction limit value mΔ of the temperature difference Δt
t is 0.2 ° C de from the temperature difference Δt at the time of checking
g, and when the detected temperature difference Δt at the time of the check is greater than 1.2 ° C. deg and less than 1.4 ° C. deg, the reduction limit value mΔt of the temperature difference Δt is set to 1.2 ° C.
deg, and the detected difference temperature Δt at the time of the check is 1.2
If the temperature is not more than ° C deg, a stop command is immediately given to the fan 3 at the time of the check to automatically stop the drying process.

The differential temperature Δt at the check time, which is used as a reference for determining the differential temperature decrease limit value mΔt, is the same as the stop timing determination switching mode employed from the time of the check. The temperature difference Δt at the time when the mode is switched to the cooling / dehumidification mode in the fan reverse operation for the first time is adopted as the temperature difference Δt at the time of the check.

Then, after the determination of the differential temperature decrease limit value mΔt at the time of the check, switching between the heating dehumidification mode and the cooling dehumidification mode is performed in the switching mode for determining the stop timing as described above, and the fan normal operation and the fan reverse operation. In performing the switching with the operation, the temperature difference Δt (= t1−t2) at the time of switching from the heating dehumidification mode in the fan normal operation to the cooling dehumidification mode in the fan reverse operation is monitored. When the temperature difference Δt of the fan 3 reaches the temperature difference limit value mΔt determined as described above, the fan 3
To stop the drying process automatically.

When the “weight-based mode” is selected, after the check point has passed, the drying object X closer to one side
When the detected weight W becomes the target finished weight mW, a stop command is given to the fan 3 to automatically stop the drying process. In this example, even when the “weight-based mode” is selected, the drying process is automatically stopped immediately when the temperature difference Δt becomes 1.2 ° C. deg or less.

In short, the control device 9 performs the following (A)
(D) Calculate the decreasing speed gradient V during the drying process of the temperature difference Δt detected by the first and second temperature sensors S1 and S2 as the temperature difference detection means, and (b) weight detection means When the detected weight W detected by the weight sensor 10 is reduced to a check weight cW which is larger than the target finished weight mW by a predetermined ratio k% as a check point, the change in the decreasing speed gradient V until the check point is reached. Based on the, select whether to perform the stop command assignment control in the "differential temperature reference mode" or in the "weight reference mode",
(C) When the “differential temperature reference mode” is selected, a reduction limit value mΔt of the differential temperature Δt at which the drying process should be stopped is determined according to the detected differential temperature Δt at the time of the check, and the detected differential temperature Δt is determined. When the determined decrease limit value mΔt is reached, a stop command for the drying process is given, and (d) the “weight-based mode”
Is selected, the detected weight W becomes the target finished weight m.
A stop command means for executing a command to stop the drying process when the value becomes W is constituted.

In FIG. 4, P1 indicates that the target finished weight mW is correctly set to the true finished weight sW, and the temperature difference Δt at the check time (position b) is 2.3 ° C.
g, the difference temperature / moisture content change process up to the above-mentioned automatic stop in the “differential temperature reference mode”, and P2 is a value at which the target finished weight mW is slightly smaller than 10%. Is incorrectly set to be smaller than the true finished weight sW, and at the time of checking (slightly before the position a).
The temperature difference Δt is per case was 1.6 ° C. deg, the "differential temperature reference mode" indicates the change process in the differential temperature-moisture content up to the automatic stop of the further, the temperature difference-water content Excessive change
Another arrow indicating the process indicates that the target finished weight mW is erroneously set to be larger than the true finished weight sW by 10%, and the temperature difference Δt at the time of the check is 2.0 ° C deg.
The change process of the temperature difference and the water content up to the above-mentioned automatic stop in the “weight-based mode” is shown.

After the drying process is automatically stopped, the process proceeds to a storage step of using the dehumidifier 8 to keep the inside of the storage chamber 2 in a low-temperature, low-humidity state without wind.

The moisture content α of the drying object X at the time when the drying process is automatically stopped is still lower than the allowable upper limit m of the target moisture content mα.
When the drying target X is not insufficiently dried and the drying target X is in a state of insufficient drying, a supplementary drying process is performed in a form in which the drying treatment time is artificially adjusted and managed.

The temperature difference Δt at the time of switching from the heating dehumidification mode to the cooling dehumidification mode, which is used as a control index of the drying process stop control, is more specifically, the detected room temperature t
r (= (t1 + t2) / 2) is the set temperature range (trm ±
This sampling time is defined as a sampling time from the time point lower than the upper limit value trm + dt of dt) by a predetermined temperature (for example, 0.5 ° C.) to the upper limit value trm + dt (that is, the time point of switching from the heating dehumidification mode to the cooling dehumidification mode). An example in which the average value of the difference between the detected temperatures t1 and t2 in the above is used as the difference in temperature Δt as a control index of the drying process stop control can be given as an example.

[Another Embodiment] Next, another embodiment will be described.

(1) In the above embodiment, the fan 3
Although the drying air A and the ventilation direction to the storage chamber 2 are determined at predetermined time intervals T1 and T2 by switching between the normal and reverse rotations of the above, the drying air A always flows in the storage chamber 2 in a fixed direction. The invention may be practiced.

(2) In the “differential temperature reference mode”, in order to determine the reduction limit value mΔt of the differential temperature Δt at which the drying process should be stopped according to the differential temperature (supply / exhaust temperature difference) Δt at the time of the check. The specific determination form can be variously changed, and is not limited to the determination form shown in the above-described embodiment.

(3) To determine whether to use the “differential temperature reference mode” or the “weight reference mode” based on the change in the differential temperature decreasing speed gradient V, various concrete determination modes are used. The configuration can be changed. For example, in the above-described embodiment, a value (r × Vn−1) that changes according to the average decreasing speed gradient Vn−1 is adopted as the determination threshold Vm. A mode in which a fixed value is used as the determination threshold value Vm may be adopted.

(4) The drying process stop command given by the stop command means 9 may be a notification operation command to a notification means for urging the operator to stop the drying process.

(5) Regarding the drying target X, various crops and articles, including the raw radish of shredded radish, can be dried.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the attached drawings.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a dryer.

FIG. 2 is a graph showing a change in supply / exhaust temperature in a drying process.

FIG. 3 is a control flowchart for stopping a drying process.

FIG. 4 is a graph for explaining a control mode of stopping a drying process.

FIG. 5 is a graph showing a relationship between a temperature difference (supply / exhaust temperature difference) and a water content.

FIG. 6 is a graph showing the relationship between the difference temperature at the time of checking and the difference temperature variation range with respect to the target moisture content.

FIG. 7 is a graph comparing the case where the target finished weight is incorrectly set to be smaller than the true finished weight and the case where the target finished weight is excessively set incorrectly;

[Explanation of symbols]

 2 Storage chamber 3 Supply / exhaust means 9 Stop command means 10 Weight detection means 11 Finished weight setting means X Drying target A Drying air cW Check weight k Predetermined ratio W Weight of drying target mα Target moisture content mW Target finished weight mΔt Decrease Limit value S1, S2 Differential temperature detecting means Δt Supply / exhaust temperature difference (differential temperature) V Decreasing speed gradient of differential temperature

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroyuki Yamakawa 1-1-1 Hama, Amagasaki City, Hyogo Prefecture Inside Kubota Technology Development Laboratory Co., Ltd. (56) References JP-A-49-66441 (JP, A) 52-102157 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F26B 25/00

Claims (1)

(57) [Claims] An air supply / exhaust means (3) for passing drying air (A) through a storage chamber (2) for storing an object to be dried (X).
Weight detection means (10) for detecting the weight (W) of the object to be dried (X) in the storage chamber (2); and the object to be dried (X) when dried to a target moisture content (mα) A finished weight setting means (11) for setting a target finished weight (mW), which is a predicted weight of the above, and drying based on the weight detected by the weight detecting means (10) (W) and the target finished weight (mW). A dryer provided with a stop command means (9) for giving a processing stop command, wherein the temperature difference detecting means (S1), (S2) for detecting a temperature difference (Δt) between the supply and exhaust temperatures of the storage chamber (2). The stop command means (9) is provided with the following (a) to (d): (a) drying of the supply / exhaust temperature difference (Δt) detected by the differential temperature detection means (S1) and (S2). Calculating a decreasing speed gradient (V) during the processing; Weight (W) detected by output means (10)
Is reduced to a check weight (cW) larger than the target finished weight (mW) by a predetermined ratio (k), and based on the change in the decreasing speed gradient (V) up to the check point. And (c) selecting whether to perform the stop command application control in the differential temperature reference mode or the weight reference mode. (C) When the differential temperature reference mode is selected, the differential temperature detection means (S1) at the time of the check is selected. The decrease limit value (mΔt) of the supply / exhaust gas temperature difference (Δt) at which the drying process should be stopped is determined according to the detected supply / exhaust gas temperature difference (Δt) in (S2), and the difference temperature detection means (S1), The detected supply / exhaust gas temperature difference (Δt) obtained by (S2) is the determined decrease limit value (mΔ
At t), a command to stop the drying process is given. (d) When the weight reference mode is selected, when the weight (W) detected by the weight detecting means (10) becomes the target finished weight (mW) Give a stop command for the drying process,
A dryer that is configured to execute.