JPH0798183A - Dryer - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent the occurrence of overdrying, and also effectively prevent the occurrence of underdrying. [Configuration] The drying process stop command means 9 is configured to perform a drying process according to the detected supply / exhaust gas temperature difference Δt at the check time when the detected weight W is reduced to a check weight cW that is larger than the target finished weight mW by a predetermined ratio k. The decrease limit value mΔt of the supply / exhaust gas temperature difference Δt to be stopped is determined, the predetermined standby time T is measured from the check time, and the detected supply / exhaust temperature difference Δt is the decrease limit of the determination when the predetermined standby time T elapses. When the value mΔt or less, or when the detected supply / exhaust gas temperature difference Δt becomes equal to or less than the determined reduction limit value mΔt after the elapse of the predetermined waiting time T, the instruction to stop the drying process is given.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dryer used for the production of shredded radish and the like. More specifically, the present invention relates to a drier for supplying drying air to a storage chamber for storing an object to be dried, and drying in the storage chamber. Weight detection means for detecting the weight of the object,
Finished weight setting means for setting a target finished weight, which is the predicted weight of the object to be dried when dried to the target moisture content, a weight detected by the weight detection means, and a drying treatment based on the target finished weight. The present invention relates to a dryer provided with stop command means for giving a stop command.

[0002]

2. Description of the Related Art Conventionally, in the above-mentioned dryer, the operator empirically judges the predicted weight (target finish weight mW) of the object to be dried when it is dried to the target water content mα, and this target While the finished weight mW is set by the finished weight setting means, the stop command means simply causes the weight W of the object to be dried detected by the weight detection means to be W.
Is configured to give a stop instruction for the drying process when the target finished weight mW is reduced, in other words,
Based only on the comparison between the target finished weight mW manually set based on experience and the weight W detected by the weight detecting means,
The mode in which the time point at which the drying process should be stopped is determined has been adopted.

[0003]

However, in the conventional dryer, the true finish weight sW of the object to be dried, which has been dried to the target water content mα, does not reach the target finish weight mW set as described above to some extent. Since there is an error, 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 is, the drying target is not sufficiently dried, and conversely, when the stop command is given by the stop command means, the water content α of the drying target is already the desired target. Greater than the water content mα,
It happened that the object to be dried was over-dried.

That is, in the error form in which the target finished weight mW is set excessively with respect to the true finished weight sW, the time at which the stop command is given by the stop instruction means is earlier than the proper time at which it is given by an error, and insufficient drying occurs. 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 time at which the stop command is given by the stop instruction means is delayed by an error from the proper time at which overdrying is performed. It was supposed to be invited. Then, although insufficient dryness can be dealt with by performing a replenishing drying process again, overdrying cannot be dealt with, resulting in a large reduction in finish quality due to overdrying, and a reduction in product quantity. There was a problem inviting.

An object of the present invention is to give an instruction to stop the drying process with a rational determination of the dry state, so that overdrying caused by the target finish weight being erroneously set to be smaller than the true finish weight. This is to ensure that it can be reliably prevented and, at the same time, to effectively prevent the occurrence of insufficient drying.

[0006]

The dryer according to the present invention is characterized in that the air supply / exhaust means for ventilating the drying air into the storage chamber for storing the object to be dried and the weight of the object to be dried in the storage chamber are detected. Weight detecting means, a finish 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 the target finish. In a configuration provided with a stop command means for giving a stop command of the drying process based on the weight, a temperature difference detecting means for detecting a supply / exhaust temperature difference of the storage chamber is provided, and the stop command means includes the following (i) to ( C), (a) Check when the weight (W) detected by the weight detecting means (10) has decreased to a check weight (cW) which is larger than the target finished weight (mW) by a predetermined ratio (k). As a point, a reduction limit value (mΔt) of the supply / exhaust gas temperature difference (Δt) at which the drying process should be stopped according to the detected supply / exhaust gas temperature difference (Δt) of the temperature difference detecting means (S1), (S2) at the time of the check. ),
(B) A predetermined waiting time (T) is measured from the time of the check, (c) When the predetermined waiting time (T) has elapsed, the temperature difference between the supply and exhaust temperatures detected by the temperature difference detecting means (S1), (S2). When (Δt) is less than or equal to the reduction limit value (mΔt) determined, or after the elapse of the predetermined waiting time (T), the difference in the detected supply / exhaust temperature by the temperature difference detecting means (S1), (S2). When (Δt) becomes equal to or smaller than the determined reduction limit value (mΔt), the instruction to stop the drying process is given.

[0007]

In other words, in the form in which the object to be dried in the storage chamber is dried by the ventilation of the drying air to the storage chamber, as the water content α of the object to be dried decreases as the drying progresses, the water evaporation from the object to be dried evaporates. The amount of heat of vaporization from the drying air decreases, and from this, the supply / exhaust temperature difference Δt (= ti-to, where ti: of the drying air supplied to the storage chamber) The 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. Then, as a result of further research on the relationship between the water content α and the supply / exhaust temperature difference Δt (hereinafter, simply referred to as temperature difference), the water content α and the temperature difference Δt generally have the following correlation. It has been found.

That is, FIG. 5 shows, as an example, the water content α and the temperature difference Δ in the shredded radish manufacturing process in which radish is the object to be dried.
shows the correlation with t, and each solid line in the figure indicates the amount of radish as an object to be dried, the installation state in the storage chamber, or
The experimental results when the 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 the same as the above operating conditions. Some variations due to differences (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 (indicated by the dashed line of H) and a lower limit (indicated by the dashed line of L), and the progress of drying causes the water content α.
The lower the temperature difference, the lower the upper limit and the lower limit of the variation of the differential temperature Δt with the reduction of the variation width.

In other words, the water content α with respect to each value of the temperature difference Δt has some variations depending on the operating conditions, but the variation of the water content α is the lower limit (corresponding to the one-dot chain line of H above). There is an upper limit (corresponding to the one-dot chain line of L above), and as the drying progresses and the differential temperature Δt decreases,
The water content α decreases as the variation width decreases.

Therefore, if a specific correlation between the water content α and the temperature difference Δt for a specific object to be dried is quantitatively grasped beforehand based on experiments and the like (see FIG. 6),
Even if the target finish weight mW may be erroneously set, at a proper check time before the weight W of the object to be dried reaches the target finish weight mW, the temperature difference Δt at the check time and the target water content mα are compared. By comparing with the differential temperature variation range mD (in other words, comparing the variation range of the water content α with respect to the temperature difference Δt at the time of the check and the target water content mα), the following determination can be made for the water content α. .

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

As a result of comparison, when the temperature difference Δt at the time of checking is within the temperature difference range mD with respect to the target water content mα (for example, the temperature difference Δ at the time of checking in FIG. 6).
When t = Δt2), it can be determined that the water content α may already be equal to or less than the target water content mα at the time of the check.

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

Further, in general, the target water content mα has a certain allowable range such that the target water content mα is the center value. Therefore, at the appropriate check point as described above, the target water content mα is within the allowable range. By comparing the differential temperature variation range mD ″ with respect to the lower limit mα ″ and the water content α at the time of checking, the following determination can be performed 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 checking is larger than the upper limit of the temperature difference range mD ″ with respect to the lower limit mα ″ of the target water content mα (for example, in FIG. 6, the temperature difference Δt at the time of checking = At Δt3),
At the time of the check, even if the water content α is equal to or lower than the target water content mα, it can be determined that it is still certainly larger than the allowable range lower limit mα ″ of the target water content mα, and the drying process is further advanced from the time of the check. Even if the temperature difference Δt
It can be determined that the water content α is not smaller than the lower limit mα ″ of the target moisture content mα ″ until the upper limit of the temperature difference variation range mD ″ with respect to the target lower limit mα ″ of the water content mα.

As a result of the comparison, when the temperature difference Δt at the time of checking is within the temperature difference range mD ″ with respect to the allowable range lower limit mα ″ of the target water content mα (for example, in FIG. 6, the temperature difference Δt at the time of checking = At the time of the check, it can be determined that the water content α may already be equal to or less than the allowable lower limit mα ″ of the target water content mα at the time of the check, and as a result of the comparison, the temperature difference Δ at the time of the check
When t is less than or equal to the lower limit of the differential temperature variation range mD ″ with respect to the allowable range lower limit mα ″ of the target water content mα, the water content α has already been assured at the time of the check.
It can be determined that the value is equal to or less than the lower limit mα ″ of α.

On the other hand, the weight cW (= mW + k × mW /) which is larger than the target finished weight mW by a predetermined ratio k%.
Assuming that 100) is the check weight, and the time when the detected weight W of the object to be dried is reduced to the check weight cW is the above check time, the target finished weight mW is smaller than the k% and is smaller than the true finished weight. In the situation where the detection weight W has become the check weight cW in the setting (erroneous setting on the overdrying side), the temperature difference Δt at the time of the check is within or below the temperature difference variation range mD with respect to the target water content mα. Even if (in the judgment based on the temperature difference Δt at the time of the check, the water content α is already the target water content m
Even if it may be less than α), the error of the target finish weight mW to the under side is less than k% and the check weight cW is still larger than the true finish weight. The water content α is never actually smaller than the target water content mα.

That is, in the 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 horizontal axis direction is the position corresponding to the true finished weight sW, and
The position b corresponds to the correctly set target finish weight mW, and the position b on the high water content side by k% weight from that position is the position of the check weight cW with respect to the correctly set target finish 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 set in the erroneous setting smaller than the true finished weight sW.
Is the position corresponding to the true finished weight sW, whereas the position corresponding to the erroneously set target finish weight mW is the 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 for the target finish weight mW which is set incorrectly.
W and the position at the time of checking.

If the target finish weight mW is smaller than the true finish weight sW and the error in erroneous setting is less than the above k%, the position of the check weight cW, that is, the position at the time of checking is the target. Position b at the time of checking when the finished weight mW is correctly set to the true finished weight sW and position a at the time of checking when the target finished weight mW is erroneously set to be smaller than the true finished weight sW by k%. It will be located between and.

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 less than or equal to k% of the target finished weight mW, the temperature difference Δt at the time of checking when the detected weight W becomes the check weight cW is within or below 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, even if the water content α may already be less than or equal to the target water content mα, the error of the target finished weight mW toward the underside is k% or less. Since the check weight cW is still larger than the true finished weight sW, the water content α at the time of the check never actually becomes smaller than the target water content mα.

In other words, in setting the target finished weight mW, if the target finished weight mW may be erroneously set smaller than the true finished weight sW up to a maximum k% of the target finished weight mW, the check weight is set. If the value of k% as the maximum possible error is adopted as the above-mentioned predetermined ratio that determines the cW and the check time, even if there is an error in the setting of the target finished weight mW, the detected weight W is It can be surely avoided that the water content α is already smaller than the target water content mα at the time of the check when the check weight becomes cW.

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

In short, in the form in which the check time is a point when the detected weight W is reduced to the check weight cW which is larger than the target finished weight mW by a predetermined rate, the check weight cW and the above-mentioned predetermined rate for determining the check point are suitable. If a different value is adopted, the water content α will be 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 becomes α and the error is uncertain, as long as it is within the expected normal error range,
When the check time is reached, the water content α has already reached the target water content m
While surely avoiding that it is smaller than α, at the time of the check, the reduction limit value mΔt of the differential temperature Δt, which is the extent to which the differential temperature Δt can be finally reduced, that is, the target moisture content mα, or the reduction limit value mΔt of the differential temperature Δt, which is an index of how much the water content α can be finally reduced within a range in which there is no possibility of becoming smaller than the lower limit mα ″ of the allowable range, With various judgment forms such as
Can be determined according to.

Therefore, the reduction limit value mΔt of the differential temperature Δt is determined according to the detected differential temperature Δt at the time of checking in this way,
By adopting a mode in which a stop command is given when the detected temperature difference Δt reaches the reduction limit value mΔt for the determination, regardless of the target finish weight mW being erroneously set to be smaller than the true finish weight sW. While reliably avoiding overdrying such that the water content α falls below the target water content mα or the lower limit mα ″ of the permissible range, the water content α is set to the target water content m.
It is possible to give a stop command at the time when it is brought as close as possible to α.

On the other hand, as described above, the temperature difference Δt at the time of checking is
In the embodiment in which the decrease limit value mΔt of the temperature difference Δt is determined according to the above, if the temperature difference Δt at the check time is equal, the temperature difference decrease limit value mΔt is equal regardless of the displacement at the check time due to the error of the target finished weight mW. Is determined and adopted, for example, when the corresponding position (x position) at the check time is at the corresponding position a of the target moisture content mα, as in the case where the state at the check time is given by the point Px in FIG. That is, when the target finished weight mW is erroneously set to be smaller than the true finished weight sW by the predetermined ratio k%), and when the check state is given by the point Py in FIG. The position at the time of check is different from the case where the corresponding position (y position) of is located on the much higher water content side than the corresponding position a of the target water content mα. Sometimes differential temperature Delta] t in their check point equivalent (Δt = Δt4) and become mutually equal differential temperature reduction limits mΔt is determined and adopted.

From this, therefore, if the form in which the stop command is given when the temperature difference Δt reaches the reduction limit value mΔt for determination is simply adopted, even if the temperature difference Δt at the time of checking is the same, the time difference at the time of checking will be the same. Is located on the high moisture content side (especially if the target finish weight mW is set too much larger than the true finished weight sW and the corresponding position at the time of check is displaced to the high moisture content side). ), The water content α when the temperature difference Δt reaches the determination decrease limit value mΔt and the stop command is given, is not yet sufficiently close to the target water content mα, resulting in insufficient drying. Can happen.

Regarding this, when paying attention again to the correlation between the water content rate α and the temperature difference Δt, the decreasing gradient of the temperature difference Δt becomes larger in the temperature difference Δt as the water content rate α decreases to some extent as the drying process proceeds. There is a characteristic, reflecting this, the differential temperature Δ
The rate of decrease in t (the amount of decrease in the temperature difference Δt in a unit time) also has a transitional range that transiently increases. However, if the drying process is further advanced beyond this range, water evaporation from the object to be dried will occur. It becomes difficult and the rate of decrease of water content α (the amount of decrease of water content α per unit time) itself becomes small,
It can be seen that the decreasing rate of the differential temperature Δt is also considerably smaller than the value from the start of the drying process to that point.

Therefore, in the drying process in which the target moisture content mα is set in the moisture content range in which such a decrease in the temperature difference decreasing rate is observed (see FIG. 7), the state at the time of checking is the point Px.
In the case where the corresponding position at the check time is at the corresponding position a of the target water content mα as in the case given by, it takes a corresponding time Tm from the check time until the temperature difference Δt reaches the decrease limit value mΔt of the determination. On the other hand, in the case where the corresponding position at the time of check is located on the high water content side as in the case where the state at the time of check is given by the point Py, the temperature difference Δt at the time of check is equal and equal. Even if the reduction limit value mΔt is adopted, the time from the check time until the temperature difference Δt reaches the determined reduction limit value mΔt becomes shorter than the corresponding time Tm.

From this, a predetermined stop waiting time T is determined as an appropriate time corresponding to the above-mentioned corresponding time Tm, and simply the temperature difference Δ after the check time.
Instead of giving a stop command when t reaches a reduction limit value mΔt for determination, the above-described predetermined waiting time T is counted from the time of checking, and the temperature difference Δt is determined when the predetermined waiting time T elapses. When the temperature difference Δt is less than or equal to the reduction limit value mΔt of the determined value, or when the temperature difference Δt is less than or equal to the reduction limit value mΔt of the determination after the elapse of the predetermined waiting time T, a mode of giving a stop instruction of the drying process is adopted. By doing so, it is possible to prevent the occurrence of insufficient drying as described above due to the corresponding position at the time of the check being located on the high water content side.

[0031]

That is, according to the characteristic configuration of the present invention,
Despite the fact that the target finished weight may be erroneously set to be smaller than the true finished weight, it is possible to reliably avoid uncontrollable quality deterioration such as overdrying and loss of product quantity. By setting the finished weight, it is possible to effectively suppress the occurrence of insufficient drying due to the above-mentioned position corresponding to the check time being on the high water content side. However, since the degree of insufficient drying is slight, the replenishment drying process can be performed easily and accurately, and as a result, it is possible to stably and easily secure high finish quality with an appropriate product amount as a whole. Like

[0032]

EXAMPLES Next, examples will be described.

FIG. 1 shows the structure of the dryer. 1 is a dolly for loading and storing the object X to be dried (raw material of shredded radish etc.) in a plurality of upper and lower stages, and 2 is a dolly on which the object X to be dried is placed. 1 is a storage chamber that stores 1 side by side in one side of the room and the other side.
Reference numeral 3 is a fan for ventilation drying, which serves as a supply / exhaust means and can be switched between normal and reverse directions. By operating the fan 3 in the normal direction, one side of the storage chamber 2 is changed to the other side as indicated by a solid arrow. The drying air A is ventilated, and by the reverse operation, the drying air A is ventilated from the other side of the storage chamber 2 to the one side as indicated by the dashed arrow in the figure.

Numerals 4 and 5 open the outside air ports 6 and 7 and close the circulation air passage to the dehumidifier 8 in the postures shown by the alternate long and short dash lines in the figure, and the postures shown by the solid lines in the figure. It is a damper that switches the air passage to a circulating air ventilation state in which the mouths 6 and 7 are closed and the circulation air passage for the dehumidifier 8 is opened. By operating the fan 3 in the normal direction, the outside air OA taken in from the outside air outlet 6 on the upper side is used as the drying air A on one side of the storage chamber 2 (right side in the figure).
From outside to outside while discharging the outside air OA from the outside through the outside air outlet 7 on the lower side, and by operating the fans 3 in the reverse direction with the dampers 4 and 5 in the outside air ventilation state. , The other side of the storage chamber 2 (the left side in the figure) using the outside air OA taken in from the lower outside air port 7 as the drying air A.
The outside air OA after the ventilation is exhausted to the outside through the outside air outlet 6 on the upper side, and automatically alternates between the outside air OA and the outside air OA. Dry it.

Further, in a situation where the drying process by the ventilation of the outside air OA cannot be carried out, the air dehumidified by the dehumidifier 8 is stored as the drying air A by rotating the dampers 4 and 5 in the circulating ventilation state and operating the fan 3 in the normal direction. Ventilation from one side (right side in the figure) of the chamber 2 to the other side, and normal circulation operation in which the air after ventilation is returned to the dehumidifier 8 and rotation of the fans 4 in the same manner with the dampers 4 and 5 operating in reverse. As a result, the air dehumidified by the dehumidifier 8 is used as the drying air A on the other side of the storage chamber 2 (on the left side in the drawing).
From one side to one side, and the circulating ventilation reverse rotation operation for returning the air after ventilation to the dehumidifier 8 is automatically and alternately performed, whereby the dehumidifier 8 is forced to dry the object X to be dried in the room. .

The dehumidifier 8 includes an indoor evaporator 8a for cooling and dehumidifying the air returned 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. And a heating and dehumidifying mode in which the entire amount of refrigerant condensation is performed in the indoor condenser 8b to increase the amount of reheat, and a part of the refrigerant condensation is condensed outdoors. The cooling and dehumidifying mode in which the amount of reheat by the indoor condenser 8b is made small by making it performed by the reactor 8c can be selectively performed, and is stored in the set temperature range (trm ± dt) centered on the set room temperature trm. Room temperature tr of room 2
In order to maintain the above, the operation mode is automatically switched between the heating dehumidification mode and the cooling dehumidification mode based on the detection of the room temperature of the storage chamber 2.

A temperature sensor is used to detect the room temperature of the storage chamber 2, and the temperature of the air supplied to the storage chamber 2 during the normal fan operation is t.
i, and the first temperature sensor S1 for detecting the ventilation temperature t1 at one end of the storage chamber, which is the exhaust gas temperature to from the storage chamber 2 during the fan reverse rotation operation, is provided. A second temperature sensor S2 for detecting the ventilation temperature t2 at the other end of the storage chamber, which is the exhaust temperature to from the chamber 2 and is the air supply temperature ti to the storage chamber 2 during the fan reverse rotation operation, is provided. The temperature t detected by each of the first temperature sensor S1 and the second temperature sensor S2
The average temperature of 1 and t2 is the detection room temperature tr (= (t
It is adopted as 1 + t2) / 2).

Reference numeral 9 denotes a controller for automatically switching between the heating dehumidifying mode and the cooling dehumidifying mode, automatically switching between the fan forward rotation operation and the fan reverse rotation operation, and automatically stopping the drying process. Regarding the automatic switching between the cooling and dehumidifying modes, 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). A configuration in which 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.

Regarding the automatic switching between the fan forward rotation operation and the fan reverse rotation operation, the drying object X on the truck 1 closer to one indoor side and the drying object X on the truck 1 closer to the other indoor side are respectively Irrespective of the difference in weight and the difference in initial water content, the test fan forward rotation operation at the beginning of the drying process is performed to reduce the weight to the check weight cW described later in the same drying process time so that the weight decreases to one side. Weight reduction amount of the object X per unit time, weight reduction amount of the object X to be dried on the other side in the experimental fan reversal operation at the beginning of the similar drying process, and the test fan operation Weight W and check weight c of each of the subsequent dried objects X
Based on the difference from W (W-cW), a predetermined forward / reverse rotation cycle T
The forward rotation operation time T1 and the reverse rotation operation time T2 (= T-T1) at (for example, 100 minutes) are determined, and after the experimental fan operation at the beginning of the drying process, both the objects X to be dried have a check weight cW. These forward rotation time T
The fan forward rotation operation of No. 1 and the fan reverse rotation operation of the reverse rotation operation time T2 are alternately repeated.

In FIG. 2, the point where 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 at the time of switching between the fan forward rotation operation and the fan reverse rotation operation. Correspond. Further, since FIG. 2 shows the experimental data, there are some disturbances in data values due to various disturbances.

On the other hand, regarding 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 object X to be dried on one side and the weight W of the object X to be dried on the other side. 10 is provided on each of the carriages 1 and, for each of the one-side drying target X and the other-side drying target X, a target finish that is a predicted weight when the drying target X is dried up to the target moisture content mα. Weight mW,
A setting device 11 is provided as a finish weight setting means that is set by the operator by judging from the initial state of each drying object X.

Then, the controller 9 is configured to perform the following control operations (1) to (3) in response to the information from the weight sensor 10 and the setting device 11:

For each of the one-side drying target X and the other-side drying target X, a weight (mW + k × mW / 100) larger than the target finished weight mW set by the setter 11 by a predetermined ratio k% is set. Check weight cW. In this example, since the target finished weight mW may be erroneously set to ± 10% as the maximum error with respect to the true finished weight sW in which the drying target X has the target water content mα. 10% is adopted as a specific numerical value for the predetermined ratio k% that determines the check weight cW.

A point of time when the detected weight W of the object X to be dried closer to one side, that is, the object X to be dried which is on the windward side in the normal rotation operation of the fan is reduced to the check weight cW is set as a check time. Alternate switching between the heating dehumidifying mode and the cooling dehumidifying mode and alternate switching between the fan forward rotation operation and the fan reverse rotation operation are performed in a switching mode for determining the stop timing. And
As a switching mode for determining the stop timing (see FIG. 2), the heating dehumidification mode is executed by the fan normal rotation 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. Until the lower limit value trm-dt of the set temperature range is reached, the cooling and dehumidifying mode is alternately executed by the fan reverse rotation operation.

That is, in the relationship between the water content α and the temperature difference Δt, the temperature difference Δt with respect to each value of the water content α varies slightly depending on the operating conditions, but the temperature difference Δt varies. There is an upper limit and a lower limit, and as the water content α decreases as the drying progresses, there is a correlation that the variation in the temperature difference Δt is reduced in both the upper limit and the lower limit while the variation width is reduced. In H, the upper limit change line of the differential temperature variation range is shown, and L shows the lower limit change line of the differential temperature variation range, but in the situation where the target finish weight mW is correctly set to the true finish weight sW. , The target water content m in the horizontal axis direction in FIG.
The position a corresponding to α is the position corresponding to the true finished weight sW and also the 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 the amount of% weight corresponds to the check weight cW and the check time for the target finish weight mW set correctly.

The target finished weight mW is k = 10.
%, The target water content mα in the horizontal axis direction in FIG. 4 is set in the erroneous setting smaller than the true finished weight sW.
The position a corresponding to the true finished weight sW is the position corresponding to the erroneously set target finished weight mW, while the position corresponding to the erroneously set target finished weight mW is the position c on the low water content side by k = 10% weight. Therefore, the position a corresponding to the target water content mα becomes the check weight cW for the erroneously set target finish weight mW and the position corresponding to the check time, and the target finish weight mW is lower than the true finish weight sW.
Is small and the error due to incorrect setting is k = 1 above.
If it is less than 0%, the position of the check weight cW and the corresponding position at the time of the check are the position b at the time of the check when the target finished weight mW is correctly set to the true finished weight sW and the target finished weight mW. Only k = 10%, which is smaller than the true finished weight sW, is located between the position a and the position a at the time of checking when the setting is erroneous.

Further, in the 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 located on the higher water content side than the position a corresponding to the target water content mα, the check weight and the check time are accordingly changed. The corresponding position is also
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 water content side than the position b at the time of checking.

Temperature t detected by the first temperature sensor S1
1 and the temperature t2 detected by the second temperature sensor S2, that is, the supply / exhaust temperature difference of the storage chamber 2 (difference temperature Δt = ti−t
o) is monitored, and the reduction limit value mΔt of the temperature difference Δt is determined according to the temperature difference Δt at the time of the above check.

Specifically (see FIG. 4), when the drying object X is a raw material of shredded radish, the target water content mα = 20%
The variation range mD of the temperature difference Δt is 1.2 to 2.0
° C deg or lower limit of allowable range of target water content mα mα ″ =
The variation range mD ″ of the differential temperature Δt with respect to 18% is 1.1.
˜1.8 ° C. deg, while the detected temperature difference Δt at the time of checking is 1.8 ° C. deg or more, the temperature difference Δ
The decrease limit value mΔt of t is set to 1.8 ° C. deg, and the detected temperature difference Δt at the time of check is 1.8 ° C.d when 1.4 ° C. deg or more.
When it is less than eg, the reduction limit value mΔt of the temperature difference Δt
0.2 ° C deg from the temperature difference Δt at the time of checking
However, the detected temperature difference Δt at the time of checking is 1.
When it is higher than 2 ° C. deg and lower than 1.4 ° C. deg, the reduction limit value mΔt of the differential temperature Δt is set to 1.2 ° C. de.
g, and the detected temperature difference Δt at the time of checking is 1.2 ° C d
If it is less than or equal to egg, a stop command is immediately given to the fan 3 at the time of the check to automatically stop the drying process.

The temperature difference Δt (= ti-to,
At the time of switching from the heating dehumidifying mode to the cooling dehumidifying mode, Δt = t1−t2 in the fan normal rotation operation and Δt = t2−t1 in the fan reverse rotation operation show a peak value, and therefore, in this example, the purpose is to improve the control accuracy. As the temperature difference Δt at the time of switching from the heating dehumidifying mode to the cooling dehumidifying mode.
Is used as a control index for the drying process stop control, and accordingly, the above-mentioned stop timing determination switch adopted from the check time is also adopted for the temperature difference Δt at the check time, which serves as a criterion for determining the temperature difference reduction limit value mΔt. In the embodiment, the temperature difference Δt when the heating dehumidification mode in the normal fan operation is switched to the cooling dehumidification mode in the reverse fan operation is adopted as the temperature difference Δt at the time of checking.

A predetermined waiting time T is counted from the time of checking. In this example, the temperature difference Δt when the object X to be dried reaches the target water content mα = 20% is further decreased by 0.2 ° C. deg (in other words, the water content α decreases from the target water content mα = 20% to the lower limit mα ″ = 18% of the allowable range) in the experiment, whereas the predetermined waiting time T is the time required for the experiment described above. The time equal to or slightly shorter than Tm is adopted After the check time, the heating dehumidification mode and the cooling dehumidification mode are switched by the switching mode for determining the stop timing as described above, and the fan forward rotation operation and the fan reverse rotation are performed. In performing the switching to the operation, the temperature difference Δt (= t1-t2) at the time of switching from the heating dehumidifying mode in the normal fan operation to the cooling dehumidifying mode in the reverse fan operation is monitored, and When the temperature difference Δt at the time of replacement is equal to or less than the temperature difference reduction limit value mΔt already determined in the above at the time when the above-described predetermined waiting time T has elapsed, or after the above-mentioned predetermined waiting time T has elapsed, the decrease is determined. When it becomes less than the limit value mΔt, a stop command is given to the fan 3 to automatically stop the drying process.

In this example, even when the predetermined waiting time T is being measured, the automatic stop is immediately performed when the temperature difference Δt becomes 1.2 ° C. deg or less.

In summary, the control device 9 has the following (a)
~ (C), (a) Weight sensor 10 as weight detecting means
When the detected weight W is reduced to the check weight cW which is larger than the target finished weight mW by a predetermined rate k%, the check time is set as the check time, and the first and second temperature sensors S1 and S2 are used as the temperature difference detecting means at the check time. According to the detected temperature difference (supply / exhaust gas temperature difference) Δt, the reduction limit value mΔt of the temperature difference Δt at which the drying process should be stopped is determined.
(B) measuring a predetermined waiting time T from the time of checking,
(C) When the detected differential temperature Δt is less than or equal to the determined decrease limit value mΔt at the time when the predetermined standby time T has elapsed, or after the predetermined standby time T has elapsed, the detected differential temperature Δt is the determined decrease limit value m.
A stop command means for executing a dry process stop command when Δt or less is configured.

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 time of checking (position b) is 2.3 ° C. de.
In the case of g, the temperature difference Δt is determined after the elapse of the predetermined waiting time T, and the change process of the temperature difference / moisture content until the reduction limit value mΔt = 1.8 ° C. deg is reached and the above automatic stop is performed. In P2, the target finish weight mW is erroneously set to be smaller than the true finish weight sW by a value slightly smaller than 10%, and the temperature difference Δt at the time of checking (just before the position a) is 1. When the temperature is 6 ° C. deg, the temperature difference Δt is also measured after the elapse of the predetermined waiting time T.
Shows the changing process of the temperature difference and the water content until the determined decrease limit value mΔt = 1.6-0.2 ° C. deg or less and the automatic stop is performed, and P3 is the target finished weight m.
W is erroneously set slightly larger than the true finished weight sW, and at the time of check (just before position b)
When the temperature difference Δt of Δ is 1.6 ° C. deg, which is the same as the case of P2, the temperature difference Δt before the predetermined waiting time T elapses.
The change process of the differential temperature / water content until t becomes the determined decrease limit value mΔt = 1.6-0.2 ° C. deg or less and the above-mentioned automatic stop is performed when the predetermined waiting time T elapses is shown.

After the drying process is automatically stopped, the dehumidifier 8 is used to move to a storage step of keeping the inside of the storage chamber 2 in a low-temperature low-humidity state with no wind.

The water content α of the object X to be dried at the time when the drying process is automatically stopped is still the upper limit m of the allowable range of the target water content mα.
When the drying target X has not been reduced to α ′ and the drying target X is in an insufficiently dried state, a supplementary drying process is performed in such a manner that the drying process time is artificially adjusted and managed.

The temperature difference Δt when switching from the heating dehumidifying mode to the cooling dehumidifying mode, which is used as a control index for the drying process stop control, more specifically, the detected room temperature t.
r (= (t1 + t2) / 2) is the set temperature range (trm ±
This sampling time is the sampling time from the time point when the temperature is 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 switching time point from the heating dehumidifying mode to the cooling dehumidifying mode). An example is one in which the average value of the differential temperatures between the detected temperatures t1 and t2 in step S3 is used as the differential temperature Δt as the control index for the drying process stop control.

[Other Embodiments] Next, other embodiments will be listed.

(1) In the above embodiment, the fan 3
Although the drying air A to the storage chamber 2 and the ventilation direction are determined for each predetermined time T1 and T2 by switching between the forward and reverse rotations of the above, in the mode in which the drying air A is always passed through the storage chamber 2 in a fixed direction. The invention may be implemented.

(2) In order to determine the reduction limit value mΔt of the differential temperature Δt at which the drying process should be stopped, the specific determination mode is variously changed according to the differential temperature (supply / exhaust gas temperature difference) Δt at the time of checking. However, it is not limited to the determination form shown in the above-mentioned embodiment.

(3) The specific value of the predetermined waiting time T may be appropriately determined based on experiments and the like, and the predetermined waiting time T
Instead of using a constant value, the predetermined standby time T may be changed according to the difference between the temperature difference Δt at the time of checking and the determined temperature difference reduction limit value mΔt.

(4) The stop command for the drying process provided by the stop command unit 9 may be an informing operation command for the informing unit for urging the operator to stop the drying process.

(5) With respect to the object X to be dried, various crops / articles including the radish as a raw material for shredded radish can be objects to be dried.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

[Figure 1] Dryer configuration diagram

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

FIG. 3 is a control flow chart for stopping the drying process.

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

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

FIG. 6 is a graph showing the relationship between the temperature difference at the time of checking and the temperature difference range for the target water content.

FIG. 7 is a graph comparing cases where the temperature difference at the time of checking is the same and the corresponding position at the time of checking is different.

[Explanation of symbols]

 2 Storage chamber 3 Air supply / exhaust means 9 Stop command means 10 Weight detection means 11 Finished weight setting means X Drying object A Drying air cW Check weight k Predetermined ratio W Weight of dried object mα Target water content mW Target finished weight mΔt Decrease Limit value S1, S2 Differential temperature detection means Δt Supply / exhaust temperature difference (differential temperature) T Predetermined standby time

Claims (1)

[Claims] 1. A supply / exhaust means (3) for ventilating a drying air (A) into a storage chamber (2) which stores an object to be dried (X).
A weight detection means (10) for detecting the weight (W) of the object to be dried (X) in the storage chamber (2); and an object to be dried (X) when dried to a target water content (mα) A finish weight setting means (11) for setting a target finish weight (mW) which is a predicted weight of the item, a weight (W) detected by the weight detecting means (10), and a drying based on the target finish weight (mW). A drier provided with a stop command means (9) for giving a process stop command, wherein the temperature difference detecting means (S1), (S2) detect a supply / exhaust gas temperature difference (Δt) of the storage chamber (2). The stop command means (9) has the following (a) to (c), and (b) the weight detected by the weight detection means (10) (W).
Is reduced to a check weight (cW) which is larger than the target finished weight (mW) by a predetermined ratio (k), and is set as a check time point, and the differential temperature detecting means (S1) and (S2) detect and feed the temperature difference. Exhaust gas temperature difference (Δt)
According to the above, the decrease limit value (mΔt) of the supply / exhaust gas temperature difference (Δt) at which the drying process should be stopped is determined, (b) a predetermined waiting time (T) is measured from the time of the check, (c) the above-mentioned predetermined When the temperature difference (Δt) detected by the temperature difference detecting means (S1), (S2) is equal to or less than the determined reduction limit value (mΔt) at the time when the waiting time (T) elapses, or the above-mentioned predetermined value. When the difference (Δt) in the supply / exhaust gas temperature detected by the temperature difference detecting means (S1), (S2) becomes equal to or less than the determined reduction limit value (mΔt) after the lapse of the waiting time (T), a stop command for the drying process is given. A dryer having a configuration for performing ,.