JP2007017107A - Drying system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein energy efficiency is low in a conventional drying system. <P>SOLUTION: This drying system utilizes a compression refrigerating system, and a condenser is divided into a regulating condenser 13 capable of regulating an exhaust heat amount for radiating the heat to an outside of the system, and a heating condenser 11 for evaporating moisture in a hydrous dried treated object W by supplying the heat to the dried treated object W charged in a treating tank 5, so as to generate moistened air. The heat of condensation of water vapor is recovered as heat of a refrigerant by an evaporator 17, the recovered heat is released by the heating condenser 11 to be utilized as vaporization heat for the moisture in the dried treated object W, and the residual heat is discharged to the outside of the system by the regulating condenser 13, only about 2/3 of energy, which is 0.5kWh of consumption energy, is required thereby compared with that in a conventional electric heater. Further, a four-way valve 19 is switched during a leading-up operation period to use the regulating condenser 13 as a heat sinking evaporator, used energy is thereby restrained, and a leading-up period is shortened thereby. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a drying system, and more particularly to a closed drying system using a compression refrigeration cycle that is highly energy efficient and can reduce the influence on the surrounding environment.

  Traditionally sun-dried and air-dried are the most convenient drying methods, and if they can prevent corruption, the quality is high, but it takes a lot of space and a long time, and it is also affected by the weather, so it is industrial. It was difficult to do. In addition, both the conventional heating-type drying device and hot air drying device release high-temperature exhaust gas containing water vapor to the outside of the system, so not only a great deal of energy is wasted, but also depending on the type of material to be dried. There was a risk of adversely affecting the surrounding environment.

In order to eliminate the drawbacks associated with the conventional drying apparatus, the present inventor has proposed a new and useful drying system described in Patent Document 1.
This drying system uses a compression refrigeration cycle to release heat from the condenser and give it to the object to be dried, thereby evaporating and separating the moisture from the object to be dried and condensing the water vapor with the evaporator to condense the moisture. As a result of discharging the heat to the outside of the system and recovering the heat and returning the heat to the condenser, the energy efficiency has been successfully improved with a relatively simple structure.

JP 2004-301696 A

In the previous drying system, the drying is progressed by adjusting the amount of heat exhausted in the adjusting condenser by paying attention to the condensation temperature of the refrigerant in the heating condenser especially during the drying operation period. Even if the heat is not sufficiently deprived from the refrigerant, the cooling capacity is prevented from being lowered, and the malfunction due to freezing of the evaporator due to the release of unlimited heat is prevented.
The present inventor has made improvements while actually operating the previous drying system. In addition to the above-described effects, the present inventors have further reduced energy consumption, stabilized the quality of the material to be dried, shortened the operation period, etc. An improved drying system and its operating method that can solve the problem is proposed here.

  The invention of claim 1 is a closed system drying system using a compression refrigeration cycle unit in which a compressor, a condenser, an expansion valve, an evaporator and the like are connected by a refrigerant circulation path, and the condenser is divided into two parts. A heating condenser that generates humid air by evaporating and separating water from the dried material by supplying heat of the condenser to the water-containing dried material inserted in the treatment tank. And an adjustment condenser that is connected to the downstream side of the heating condenser and that can adjust the amount of exhaust heat that discharges heat outside the system, and a dehumidifying evaporator that dehumidifies by removing heat from the humid air, An endothermic evaporator that absorbs heat from outside the system, an air circulation means in the tank that guides the humid air in the treatment tank to a portion to be dehumidified, and guides the dehumidified air to the material to be dried, and a normal operation period A condensing pressure control for adjusting the refrigerant condensing pressure in the heating condenser constant. And a rising control means for operating the endothermic evaporator during the rising operation period and stopping the operation of the dehumidifying evaporator to raise the above-mentioned constant condensation pressure. .

  The invention according to claim 2 is the drying system according to claim 1, wherein the adjusting condenser is also used as an endothermic evaporator, and the compressor in the rising operation period is changed by changing the connection state of the four-way valve, Switch from the piping configuration of the heating condenser, expansion valve, and endothermic evaporator to the piping configuration that connects the compressor, heating condenser, adjustment condenser, expansion valve, and dehumidification evaporator during normal operation. The drying system is characterized by that.

  According to a third aspect of the present invention, in the drying system according to the first or second aspect, the condensing pressure control means includes a subcooler incorporated in the inlet of the adjusting condenser, the inlet of the expansion valve, or the outlet side of the adjusting condenser. A temperature sensor that detects the refrigerant temperature at any position immediately before the subcooler, and a controller that adjusts the amount of exhaust heat of the adjusting condenser based on the temperature detected from the temperature sensor. It is the drying system characterized by being made.

  The invention of claim 4 is the drying system according to any one of claims 1 to 3, further comprising evaporation pressure control means for adjusting the evaporation pressure in the dehumidifying evaporator within a certain range. It is a drying system.

  According to a fifth aspect of the present invention, in the drying system according to the fourth aspect, the evaporation pressure control means includes a variable capacity type compressor, a temperature sensor that detects the refrigerant temperature at the inlet or outlet of the dehumidifying evaporator, A drying system comprising: a controller that adjusts a capacity of the compressor based on a temperature detected from the temperature sensor.

  According to a sixth aspect of the present invention, in the drying system according to the fourth aspect, the evaporating pressure control means includes a variable capacity compressor, a temperature sensor that detects the refrigerant temperature at each of the inlet and outlet of the dehumidifying evaporator, The drying system is configured by a controller that adjusts the capacity of the compressor so that the refrigerant temperature difference between the two positions detected from the temperature sensor is within a certain range.

  According to a seventh aspect of the present invention, in the drying system according to any of the fourth to sixth aspects, the opening of the expansion valve can be adjusted, and the controller is configured to change the capacity of the compressor when the capacity of the compressor is changed. The drying system is characterized by adjusting the opening of the expansion valve to maintain the refrigerant flow rate appropriately at all times, and smoothly adjusting the change in the refrigerant flow rate even when the capacity change of the compressor is gradual.

  According to an eighth aspect of the present invention, in the drying system according to any one of the fifth to seventh aspects, the air circulation means in the tank is capable of adjusting the air volume, and the controller adjusts the current compressor capacity or the temperature detected by the temperature sensor. The drying system is characterized in that the air volume of the tank air circulation means is adjusted based on the drying system.

  A ninth aspect of the present invention is the drying system according to any one of the fifth to eighth aspects, further comprising stirring means capable of adjusting the speed of the operation of the stirring unit for stirring the object to be dried. The drying system is characterized in that the speed of operation of the stirring unit of the stirring unit is adjusted based on a capacity detected by a capacity or a temperature sensor.

  The invention of claim 10 is the drying system according to any one of claims 1 to 9, wherein the heating is performed from the secondary refrigerant heated by heat exchange with the high-temperature side refrigerant in the heating condenser of the compression refrigeration cycle section. Through the heat exchanger for cooling from the secondary refrigerant cooled by the thermal effect of the low-temperature side refrigerant in the dehumidifying evaporator and the indirect heating component for supplying heat to the object to be dried via the heat exchanger for heat It is provided with at least one indirect constituent part of the indirect cooling constituent part from which heat is taken away from the humid air, and the indirect constituent part of the compression refrigeration cycle part is configured to be separable from the drying system. It is a drying system.

  The invention of claim 11 is a compression refrigeration cycle section constituting the drying system described in claim 10.

  According to a twelfth aspect of the present invention, in the method for operating a drying system according to the fourth aspect, the operation period is divided into a rising operation period and a drying operation period. When the temperature reaches a temperature corresponding to a preset condensation pressure, the rising operation period is shifted to the drying operation period. During the drying operation period, the condensation temperature is adjusted to be constant by the condensation pressure control means, and the evaporation pressure is adjusted. The control means adjusts the capacity of the compressor so that the refrigerant temperature corresponding to the refrigerant evaporating pressure is within a certain range, and even if the capacity of the compressor is changed to the minimum, it falls below the lower limit of the certain range. The driving method is characterized in that the driving is ended at the time when the operation is finished.

  A thirteenth aspect of the present invention is the drying system operating method according to the twelfth aspect of the present invention, wherein the capacity of the compressor is changed stepwise and the opening of the expansion valve is adjusted when the capacity of the compressor is changed. By doing so, the fluctuation of the evaporation pressure is smoothed.

According to claim 1 of the present invention, the drying system can be operated with high energy efficiency under a normal temperature and normal pressure in a closed system. Moreover, the energy consumption during the start-up operation period is greatly reduced, and the rise time is also greatly shortened.
Claim 2 proposes a practical piping configuration that is simple and has few obstacles such as liquid back at the time of valve switching by using a four-way valve.
Claim 3 proposes a preferred specific example of the condensing pressure control means.
According to the fourth aspect, by adding the evaporation pressure control means, it is possible to operate according to the amount of water evaporation that fluctuates depending on the progress of drying, to prevent the drying efficiency from being lowered, and to end the operation from the outside of the treatment tank. Can be judged with high reliability.
Claims 5 to 7 propose suitable specific examples of the evaporation pressure control means.

According to the eighth and ninth aspects, even if the object to be dried becomes powdery as the drying progresses, scattering can be minimized.
According to claims 10 and 11, since only the compression refrigeration cycle section can be packaged as a general-purpose product, mass production is possible.
According to the twelfth and thirteenth aspects, the energy consumption is reduced throughout the entire operation period, and the operation period is also shortened. In addition, a high-quality dried processed product can always be obtained.
From the above, it can be said that the drying system of the present invention is an economical and environmentally friendly system.

A first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a schematic diagram of an entire drying system 1 according to an embodiment.
In this embodiment, the object to be dried (W) is a hydrous organic substance such as vegetables.
The drying system 1 is mainly composed of a compression refrigeration cycle unit 3 and a treatment tank 5. The drying system 1 employs a direct cooling method and a direct heating method.

First, the configuration of the compression refrigeration cycle unit 3 will be described.
As shown in FIG. 1, reference numeral 7 denotes a refrigerant circulation path, which includes a compressor 9, a heating condenser 11, an adjusting condenser / heat absorption evaporator 13, an expansion valve 15, and a dehumidifying evaporator 17. Has been.
The compressor 9 is of a variable capacity type whose capacity can be changed.
The heating condenser 11 is constituted by a heat conductive tube (made of copper) that is contact-piped so as to crawl under the floor of the treatment tank 5, and directly passes the heat of the refrigerant in the treatment tank 5 without passing air. It gives to a dried processed material (W).
The adjustment condenser / endothermic evaporator 13 is disposed outside the processing tank 5, serves as both the adjustment condenser and the endothermic evaporator, and is used as an adjustment condenser. The number of exhaust heat is adjusted by controlling the rotation speed of the fan 14 incorporated therein. When used as an endothermic evaporator, heat is taken into the refrigerant from the outside air by the heat pump principle.
In this case, the startup operation period can be shortened by increasing the rotational speed of the fan 14 as much as possible. However, when the outside air is very hot, the rotation of the fan 14 is prevented so that the inside of the compression refrigeration cycle does not become an abnormally high temperature. In some cases, the number must be suppressed. Of course, when the outside air is cold, frost formation should be prevented by appropriate operation such as adjusting the opening of the expansion valve.
The expansion valve 15 is an electronic expansion valve whose opening degree can be adjusted.
The dehumidifying evaporator 17 is incorporated in the processing tank 5.
Reference numeral 19 denotes a switchable four-way valve.

The temperature sensors S1, S2, S3, and S4 detect the temperature of the refrigerant at the position where the sensors are provided.
Reference numeral 21 denotes a controller (consisting of a CPU, a memory, an I / O port, a power supply circuit, etc.), and the controller 21 controls the entire drying system 1 according to a dedicated drying procedure. That is, it receives a signal from the temperature sensor S1 and the like, and issues a control signal to a drive circuit (not shown) such as the fan 14 of the adjusting condenser 13.

Next, the structure of the processing tank 5 will be described.
Reference numeral 23 denotes a screw as a stirring means for the object to be dried (W), and the screw 23 is installed in a portion near the floor of the treatment tank 5.
Reference numeral 25 denotes a blower as an air circulation means in the tank, and the air after dehumidification that has passed through the dehumidifying evaporator 17 is guided to the object to be dried (W) by driving the blower 25, and the object to be dried (W ), A circulation path is formed through which the humid air taken in as water vapor is led to the dehumidifying evaporator.

By switching the four-way valve 19, the piping configuration is different and the heat circulation path is different between the rising operation period and the drying operation period.
FIG. 2 shows a piping configuration during a start-up operation period. After the refrigerant is discharged from the compressor 9, the heating condenser 11 heats the material to be dried (W) in the tank from under the floor of the processing tank 5. It is deprived and condensed, decompressed by the expansion valve 15, evaporated by the endothermic evaporator 13, and returned to the compressor 9 again. At this time, the refrigerant coming out of the heating condenser passes through the dehumidifying evaporator 17 in a high temperature state, but does not function as a condenser because a blower 25 described later is not driven. Therefore, the dehumidifying evaporator 17 may be bypassed when starting up.
When the drying system 1 operates with this piping configuration, heat to be dried (W) is given from the outside air by the principle of a heat pump, and Joule heat from the compressor 9 or the like is also given and preheated.

FIG. 3 shows a piping configuration during a drying operation period. After the refrigerant is discharged from the compressor 9, the heating condenser 11 heats the material to be dried (W) in the tank from under the floor of the processing tank 5. It is deprived and condensed, the excess heat is exhausted outside the system by the adjusting condenser 13, further condensed by an appropriate amount, decompressed by the expansion valve 15, evaporated by the dehumidifying evaporator 17, and again compressed by the compressor 9. It is configured to return to.
When the drying system 1 operates with this piping configuration, as shown in FIG. 4, heat is applied to the object to be dried (W) from the heating condenser 11 to heat the object to be dried (W), Moisture is then evaporated and separated and taken into the air on the object to be dried (W) to generate moist air. The humid air is conveyed to the dehumidifying evaporator 17 along the circulation path, where water vapor is condensed and separated, and is discharged out of the system by drain. On the other hand, the dehumidified air that has been dehumidified by separation of moisture by the dehumidifying evaporator 17 is returned to the object to be dried (W) according to the circulation path. Then, the generation of humid air is repeated again.

  The arrow in the processing tank 5 in FIG. 3 indicates the air circulation path. White circles in the arrows indicate the water vapor taken in from the object to be dried (W). Note that water vapor is not shown in the arrow of the air after dehumidification, but this does not indicate dry air with zero humidity, both of which reach near 100% humidity but evaporate constantly. In order to clearly distinguish between moist air and air after dehumidification by focusing only on the amount of moisture that repeats condensation, such illustration is shown.

Hereinafter, the control means will be described.
In the drying system 1, during the start-up operation period, the condensing pressure control means detects the refrigerant temperature before the expansion valve 15, and the temperature of the refrigerant is constant based on the temperature detected from the temperature sensor S <b> 1. The controller 21 determines whether or not the “condensation temperature” = “condensation pressure” has been reached, and ends the start-up operation.
Temperature sensors S2 and S4 are provided on the inlet and outlet sides of the endothermic evaporator 13, respectively, and the opening of the expansion valve 15 is set so that the temperature difference detected from these temperature sensors S2 and S4 is constant. By adjusting the temperature, it can be used even when the outside air temperature is very low, and can be used without problems even in cold regions such as Hokkaido.
Since the refrigerant pressure and temperature are in a linear correspondence relationship, the refrigerant pressure is converted and derived by detecting the refrigerant temperature. The same applies to the following evaporation pressure control means.

During the drying operation period, the condensing pressure control means adjusts the exhaust heat amount of the adjusting condenser 13 based on the temperature sensor S2 for detecting the refrigerant temperature just before the expansion valve 15 and the refrigerant temperature detected from the sensor S2. The controller 21 controls the “condensation pressure” of the refrigerant in the heating condenser 11 to be constant (fixed).
When a subcooler is installed at the outlet of the adjustment condenser 13, the refrigerant condensing temperature is estimated based on the refrigerant temperature immediately before the expansion valve 15 detected from the temperature sensor S2, and is added from this estimated temperature. The “condensation pressure” of the refrigerant in the temperature condenser 11 may be controlled to be constant (fixed), or the temperature sensor S2 in which the position of the temperature sensor S2 is changed immediately before the subcooler and the position thereof is changed. The “condensation pressure” of the refrigerant in the heating condenser 11 may be controlled to be constant (fixed) based on the temperature detected from.
Further, as described above, when the temperature sensor S4 is arranged immediately before the adjusting condenser so that it can cope with a cold region, the refrigerant of the heating condenser 11 is based on the temperature detected from the temperature sensor S4. The “condensation pressure” may be controlled to be constant (fixed).
When the moisture in the object to be dried (W) decreases due to the progress of drying, the refrigerant is not sufficiently deprived of heat by the heating condenser 11, and the refrigerant cannot be sufficiently cooled. If such a refrigerant is carried to the dehumidifying evaporator 17 as it is, not only the drying system 1 is idled because the cooling capacity is reduced, but also the inside of the treatment tank 5 is heated to an abnormally high temperature. You will have to stop.
On the other hand, if heat is continuously released from the adjusting condenser 13 without any adjustment, the temperature of the dehumidifying evaporator 17 is lowered, and in the worst case, a malfunction such as freezing occurs.

However, in this drying system 1, since the amount of exhaust heat of the adjusting condenser 13 is adjusted, the refrigerant is not inclined to the high temperature side or the low temperature side, and the cooling capacity and the heating capacity are balanced at a high level. So use efficiency is high.
In addition, the amount of heat applied to the material is kept at the maximum while the cooling capacity of the circulating air is also maximized. As a result, the relative humidity of the air after dehumidification is preferably 90% or higher, more preferably 95% or higher. The air having a relative humidity in the range close to 100% circulates in the tank, so that the heating capacity can be used to the maximum for water evaporation, and at the same time, the cooling capacity can be used to the maximum for water condensation.
When the temperature before the expansion valve 15 is detected as in the drying system 1, it is necessary to correct the condensation temperature in consideration of the temperature decrease due to the characteristics of the adjusting condenser 13.

Since the “condensation pressure” is made constant by the condensation pressure control means, the humid air passing through the dehumidifying evaporator 17 has a relative humidity of approximately 100%, that is, a saturated water vapor amount. This is preferable from the viewpoint of efficient use of the cooling capacity.
However, when drying progresses and the amount of water evaporation decreases, the temperature of the air after dehumidification is lowered by the excess cooling capacity. At that time, if controlled only by the condensing pressure control means, the range of decrease in the temperature of the air after dehumidification becomes excessively large. As a result, the drying speed is excessively decreased, and the drying efficiency is decreased. Therefore, the decreasing rate drying period after drying is completed to some extent becomes longer.
In addition, since the controller 21 cannot receive a signal corresponding to the end signal, it is difficult to determine when to finish the drying operation.

By the way, the increase / decrease in the amount of water evaporation is correlated with the increase / decrease in the heat load of the dehumidifying evaporator 17. In addition, when the “condensation pressure” of the refrigerant is constant as described above, the increase / decrease in the heat load of the dehumidifying evaporator 17 and the “evaporation pressure” of the refrigerant are also correlated. In this drying system 1, since the condensation pressure is fixed and the humid air passing through the dehumidifying evaporator 17 has a relative humidity of approximately 100%, the heat load of the dehumidifying evaporator 17 is the object to be dried (W). When the amount of water evaporation decreases, the heat load decreases and the refrigerant “evaporation pressure” decreases.When the amount of water evaporation increases, the heat load increases and the refrigerant “evaporation pressure” Go up.
Accordingly, in terms of the relationship between the water evaporation amount and the evaporation pressure, the water evaporation amount decreases in the rate-decreasing drying period where the drying speed decreases, and this period continues in a state where the heat load of the dehumidifying evaporator 17 is insufficient. Then, the compression refrigeration cycle is inclined to the low temperature side, the drying speed is further lowered, and the energy efficiency is deteriorated. On the other hand, even in the reduced rate drying period, depending on the type of the object to be dried (W), an excessive heat load may occur on the way, but if this state continues after the capacity of the compressor 9 is reduced, the compressor 9 The refrigerant discharge temperature from the tank becomes abnormally high, and the compression refrigeration cycle is inclined to the high temperature side, and the energy efficiency is deteriorated.

Therefore, the drying system 1 includes an evaporating pressure control means that constantly adjusts the “evaporating pressure” of the refrigerant to fall within a certain range according to the drying condition, thereby enabling an energy-efficient operation even at the time of reduced rate drying. It was.
The evaporating pressure control means is detected from the compressor 9 whose capacity can be changed in stages, temperature sensors S1 and S3 for detecting the refrigerant temperature at each of the inlet and outlet positions of the dehumidifying evaporator 17, and the temperature sensors. The controller 21 adjusts the capacity of the compressor 9 based on the refrigerant temperature difference between the two positions. The refrigerant evaporation pressure measured by the sensor S1 or S3 or the refrigerant temperature difference of the dehumidifying evaporator 17 ( That is, adjustment is made so that the superheat is within a certain range.
In addition, by adjusting the opening degree of the expansion valve 15 in a corrective manner, the change in the refrigerant flow rate can be smoothly adjusted even if the capacity of the compressor 9 is changed stepwise without changing the capacity of the compressor 9 in an analog manner. As a result, the cooling capacity can be changed smoothly.

A specific control method by the evaporation pressure control means will be described below.
As shown in FIG. 5 (2), when the amount of water evaporation is too small relative to the compressor capacity, the evaporation pressure decreases and the superheat is detected to be smaller than the lower limit of the certain range. Adjustment is made to reduce the capacity of the compressor 9 until it falls within.
On the other hand, as shown in FIG. 5 (1), when the water evaporation amount becomes excessive with respect to the compressor capacity, the evaporation pressure rises and the superheat is detected to be larger than the upper limit of a certain range. Is adjusted to increase the capacity of the compressor 9 until the value falls within a certain range.
In FIG. 5, the evaporating pressure control method is shown using superheat as a determination index, but it goes without saying that the refrigerant temperature corresponding to the evaporating pressure can be used as a determination index instead of superheat. In that case, when the refrigerant temperature with respect to the evaporating pressure is detected to be smaller than the lower limit, the capacity of the compressor 9 is adjusted to be decreased, and when the refrigerant temperature is detected to be larger than the upper limit, the capacity of the compressor 9 is increased to be adjusted. Will be made.
FIG. 6 is a comparison diagram of the drying speed in the reduced rate drying operation period when the evaporation pressure control means is provided and when it is not provided. Here, the drying rate is a graph of the drain amount per hour (kg-water / hour / m2 apparent dry area) with the maximum value being 100%. The actual dry area is the sum of the surface area of the material to be dried, but since it actually varies depending on the type and condition of the material to be dried, it is difficult to calculate this. The area is calculated as the apparent dry area.

Hereinafter, the operation method of the drying system 1 will be described in accordance with the flowchart of FIG. 7 divided into a start-up operation period (preheating period) and a drying operation period (constant rate drying period, reduced rate drying period). FIG. 8 is a relationship diagram between the capacity of the compressor 9 and the drying speed.
(Rise period)
The rising operation period corresponds to a preheating period in which the object to be dried (W) is preheated.
First, after the workpiece (W) to be dried is put into the treatment tank 5, the inlet is closed to close the treatment tank 5, and then the power supply circuit of the drying system 1 is turned on to start operation. In this start-up operation period, as shown in FIG. 2, as the initial setting, the refrigerant is discharged from the compressor 9, then condensed by the heating condenser 11, decompressed by the expansion valve 15, and endothermic evaporator. The piping is evaporated at 13 and returned to the compressor 9 again, and the capacity of the compressor 9 is set to the maximum. Furthermore, by adjusting the opening degree of the expansion valve so that the refrigerant temperature difference between the inlet and the outlet of the endothermic evaporator becomes a certain level or more, it is possible to cope with a decrease in endothermic performance when the outside air temperature is low.
In this start-up operation period, heat is absorbed from outside the system by the endothermic evaporator 13 and the heat is given from the heating condenser 11 to the object to be dried (W) for heating by the heat pump principle. .

In the conventional drying system, when the object to be dried (W) has a low temperature, the heat absorption capacity of the object to be dried (W) is large, and therefore the temperature of the dehumidifying evaporator 17 provided in the treatment tank 5 is high. In particular, when the temperature of the inputted dried processing object (W) is low, in the worst case, it freezes and malfunctions.
When the object to be dried (W) is heated using only the Joule heat of the compressor 9 or the like as a heat source, this can be dealt with by increasing the capacity of the compressor 9, that is, by increasing the energy consumption. In addition, since there is a limit to increasing the capacity of the compressor 9, it is necessary to suppress the amount of heating from the heating condenser 11 to the object to be dried, and the preheating time, that is, the rise time becomes longer. Tend to.
On the other hand, since the drying system 1 absorbs heat from the outside air, the energy consumption can be greatly reduced as compared with the case where only the Joule heat is used as the heat source, and the preheating period is greatly increased. Can be shortened.

The rising period ends when the object to be dried (W) is sufficiently preheated and reaches a predetermined temperature set in advance.
The rising period ends when the condensation pressure (= condensation temperature) of the refrigerant in the heating condenser 11 reaches a certain level.

(Normal drying operation period)
During this normal operation period, as a default setting, the four-way valve 19 is switched, and as shown in FIG. 3, the refrigerant is discharged from the compressor 9 and then condensed in the heating condenser 11, and the adjustment condensation The pipe 13 is further condensed, depressurized by the expansion valve 15, evaporated by the dehumidifying evaporator 17, and returned to the compressor 9 again. The capacity of the compressor 9 is set to the minimum as it is.
When the capacity of the compressor 9 is maximized, the constant rate drying operation period is reached, the drying speed is maximized, and drying of the object to be dried (W) proceeds with high drying efficiency.

During the constant rate drying operation period, the condensation pressure is controlled by the condensation pressure control means by releasing excess heat from the adjusting condenser 13, and the drying proceeds at the maximum drying speed. The cycle unit 3 is stably and efficiently operated, and the inside of the treatment tank 5 is also maintained at normal temperature and normal pressure.
That is, during the constant rate operation period of the drying system 1, the amount of water evaporation in the object to be dried (W) and the amount of water condensation in the dehumidifying evaporator 17 are balanced and released when the water condenses to transfer to the refrigerant. The amount of latent heat to be generated is equal to and balanced with the amount of heat used when moisture is vaporized from the object to be dried (W). In addition to this, compressor generated raw heat and screw generated raw heat, which are Joule heat that continues to be generated as long as the compressor 9 and the like are driven, are brought into the system, and the amount of heat corresponding to this is also adjusted. It is discharged from the condenser 13.

  Then, when the drying progresses and the water evaporation amount decreases, the drying proceeds to a decreasing rate drying period, and the water evaporation amount decreases. However, as shown in FIG. When the amount of water evaporation becomes too small, the superheat is detected to be smaller than the lower limit of the certain range, so that the capacity of the compressor 9 is lowered step by step and the superheat is raised so that it falls within the certain range. At this time, the cooling capacity is smoothly corrected by the expansion valve 15.

When the object to be dried (W) is a vegetable, it changes from mud to clay, and when drying progresses, it changes from clay to powder, but immediately after it changes to powder, the exposed surface area. As a result, the amount of water evaporation temporarily increases. Therefore, as shown in FIG. 5 (1), the capacity of the compressor 9 is increased and the superheat is lowered to fall within a certain range.
And when the capacity | capacitance of the compressor 9 is set to the minimum, and a superheat is less than a minimum, a driving | operation is complete | finished. At this point in time, drying has progressed, indicating that there is no moisture evaporation amount commensurate with the compressor capacity, and the drying process is stopped.

  The blower 25 increases the air volume until the constant moisture drying in order to maximize the total water condensation amount. As the drying progresses and the moisture contained in the object to be dried (W) decreases and the amount of water evaporation per hour decreases, the air volume necessary for dehumidification also decreases. Reduce the air volume. Decreasing the air volume in accordance with the amount of condensed water is advantageous for achieving accurate control by increasing the energy efficiency and adjusting the air volume to match the compressor capacity. Further, when the powdered material to be dried scatters in the treatment tank 5, the evaporation of moisture is inhibited, but there is no such inconvenience because the air volume is adjusted as described above.

  Moreover, the rotational speed of the screw 23 with a shaft is adjusted. Energy efficiency can be increased by reducing the air volume according to the amount of moisture condensed. When the dried material to be dried scatters in the treatment tank 5, the evaporation of moisture is inhibited, but the rotation of the screw 23 is adjusted as described above, so there is no such inconvenience. .

A drying system 30 according to the second embodiment will be described. The drying system 30 has almost the same configuration as the drying system 1, and a temperature sensor S5 is provided in the middle of the refrigerant circulation path 7 from the four-way valve 19 to the compressor 9 instead of the temperature sensors S3 and S4. Only is different.
As shown in the simplified schematic diagrams of FIGS. 9 (1) to (3), when the temperature sensor S5 is arranged in this way and the temperature sensor S2 is used as the condensation pressure control means, one temperature sensor is used. In S5, both functions of the temperature sensors S3 and S4 can be performed. That is, during the start-up operation period, as shown in (2), the temperature sensors S2 and S5 are respectively provided on the inlet and outlet sides of the endothermic evaporator 13, and are detected from these temperature sensors S2 and S5. The opening degree of the expansion valve 15 is adjusted so that the temperature difference is constant. Further, during the drying operation period, as shown in (3), the temperature sensors S1 and S5 are respectively provided on the inlet and outlet sides of the dehumidifying evaporator 17, and are detected from these temperature sensors S1 and S5. It adjusts so that the temperature difference (namely, superheat) performed may be settled in a fixed range.

A drying system 31 according to the third embodiment will be described with reference to FIG. FIG. 10 is a schematic diagram of the entire drying system 31, and the same components as those in the drying system 1 in FIG.
This drying system 31 employs an indirect cooling / heating method, and the dehumidifying evaporator is composed of a heat exchanger 33, a dehumidifying heat exchanger 35, and a secondary refrigerant circulation path 37, and a heating condenser. Consists of a heat exchanger 39, a heating heat exchanger 41, and a secondary refrigerant circulation path 43. Circulating pumps 38 and 44 as pressure feeding means are provided in the respective secondary refrigerant circulation paths 37 and 43. For example, water can be used as the secondary refrigerant. Structurally, the heating heat exchanger 41 corresponds to the heating condenser 11 of the first embodiment (direct cooling / heating method), and the dehumidifying heat exchanger 35 corresponds to the dehumidifying evaporator 17. is doing. The dehumidifying heat exchanger 35 is provided in the processing tank 5 similarly to the dehumidifying evaporator 17.

With this configuration, the compression refrigeration cycle unit 32 can be packaged, and the connection between the packaged compression refrigeration cycle unit 32 and the drying apparatus main body dehumidifies the secondary refrigerant circulation paths 37 and 43. It is only necessary to connect to the heat exchanger 35 for heating and the heat exchanger 41 for heating, respectively, and to further connect the wiring of the power supply of the screw 23 and the blower 25.
Therefore, there are the following advantages.
(1) The compression refrigeration cycle unit can be separated from the drying apparatus main body and separately manufactured and maintained.
(2) By unifying the standard of the connection part, the compression refrigeration cycle part can be connected to the apparatus main body of various design aspects. Therefore, the convenience of the compression refrigeration cycle unit can be improved and the manufacturing cost can be reduced.
(3) Since the controller can control the entire system based on the sensor information detected on the compression refrigeration cycle unit side, there is an advantage that the operation confirmation and maintenance of the control of the drying system are facilitated.

A drying system 51 according to the fourth embodiment will be described with reference to FIG. FIG. 11 is a simplified schematic diagram of the entire drying system 51, and the same components as in the drying system 31 in FIG. This drying system 51 employs an indirect cooling method.
A drying system 53 according to the fifth embodiment will be described with reference to FIG. FIG. 12 is a simplified schematic diagram of the entire drying system 53, and the same components as in the drying system 31 in FIG. The drying system 53 employs an indirect heating method.
As shown in the above embodiment, the indirect component may be provided only on the cooling side or only on the heating side.

Although the embodiment of the present invention has been described above, the specific configuration of the present invention is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention. Included in the invention.
For example, the compressor may have a capacity that changes continuously and smoothly in an analog manner or a stepwise change.
With respect to the operation method, when a preheated material to be dried is put into the treatment tank, there is almost no rising operation period, and the operation immediately shifts to the drying operation period.
Needless to say, the object to be dried is not limited to organic matter.
The temperature sensor of the condensing pressure control means is not limited to the inlet of the adjusting condenser, that is, before the expansion valve. If a subcooler is incorporated at the inlet of the expansion valve or the outlet side of the adjusting condenser, the subcooler is not limited. It may be one that detects the refrigerant temperature at a position immediately before. This includes the case of estimating the evaporation pressure by measuring the temperature of the air circulating in the tank.

According to the drying system of the present invention, energy consumption is greatly reduced, and exhaust heat to the outside of the system is suppressed as much as possible. Therefore, it can be said to be economical and environmentally friendly.
Further, if the compression refrigeration cycle unit including the control unit can be separated from the apparatus main body, one compression refrigeration cycle part can be used for various apparatuses for general use, which is convenient and the compression refrigeration cycle. There is an advantage that parts can be mass-produced.

It is a schematic diagram of the drying system which concerns on the 1st Embodiment of this invention. It is a piping structure of the starting operation period of the drying system of FIG. It is a piping structure of the drying operation period of the drying system of FIG. It is explanatory drawing of the heat transfer cycle of a drying operation period. It is explanatory drawing of the concrete control method by an evaporation pressure control means. It is a comparison figure of the drying rate in the rate-of-decreasing drying operation period when not providing with the evaporation pressure control means. It is a flowchart of an operation method. It is a related figure of the capacity | capacitance of a compressor, and a drying speed. It is a simple schematic diagram of the drying system which concerns on the 2nd Embodiment of this invention. It is a schematic diagram of the drying system which concerns on the 3rd Embodiment of this invention. It is a schematic diagram of the drying system which concerns on the 4th Embodiment of this invention. It is a schematic diagram of the drying system which concerns on the 5th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Drying system 3 ... Compression refrigeration cycle part 5 ... Processing tank 7 ... Refrigerant circulation path 9 ... Compressor 11 ... Heating condenser 13 ... Adjustment condenser (endothermic evaporator) 14 · · · Fan 15 · · · Expansion valve 17 · · · Dehumidifier evaporator 19 · · · Four-way valve 21 · · · Controller 23 · · · Screw 25 · · · Blower S1, S2, S3, S4 · · · Temperature sensor 30 · · · Drying system S5 · · · Temperature sensor 31 Drying system 32 Compressive refrigeration cycle 33 Heat exchanger 35 Dehumidification heat exchanger 37 Secondary refrigerant circulation path 38 Circulation pump 39 Heat exchanger 41 Heating heat exchanger 43 Secondary refrigerant circulation path 44 Circulation pump 51 Drying system 53 Drying system

Claims (13)

In a closed system drying system using a compression refrigeration cycle unit formed by connecting a compressor, a condenser, an expansion valve, an evaporator, and the like through a refrigerant circulation path,
Moisture is evaporated and separated from the object to be dried by supplying heat of the condenser to the water-containing object to be dried inserted into the treatment tank provided with the condenser divided in two. A heating condenser that generates heat, an adjustment condenser that is connected to the downstream side of the heating condenser and that can adjust the amount of exhaust heat that exhausts heat to the outside of the system, and deprives heat from the humid air. A dehumidifying evaporator for dehumidifying, an endothermic evaporator for absorbing heat from outside the system, and a tank for guiding humid air to a dehumidified portion in the processing tank and for introducing the dehumidified air to the object to be dried An air circulation means, a condensing pressure control means for adjusting the refrigerant condensing pressure in the heating condenser to be constant during a normal operation period, and an operation of the dehumidifying evaporator while operating the endothermic evaporator during a rising operation period. Rise control to stop and raise to the above-mentioned constant condensation pressure Drying system, characterized in that it comprises a stage.   The drying system according to claim 1, wherein the adjusting condenser is also used as an endothermic evaporator, and the compressor, the heating condenser, the expansion during the start-up operation period are changed by changing the connection state of the four-way valve. It is possible to switch from a piping configuration of a valve and an endothermic evaporator to a piping configuration in which a compressor, a heating condenser, a regulating condenser, an expansion valve and a dehumidifying evaporator are connected during a normal operation period. system.   3. The drying system according to claim 1 or 2, wherein the condensing pressure control means includes a subcooler incorporated in the inlet of the adjusting condenser, the inlet of the expansion valve, or the outlet side of the adjusting condenser. A temperature sensor that detects the refrigerant temperature at any position immediately before the subcooler, and a controller that adjusts the amount of exhaust heat of the adjusting condenser based on the temperature detected from the temperature sensor, Drying system.   4. The drying system according to claim 1, further comprising evaporation pressure control means for adjusting an evaporation pressure in the dehumidifying evaporator within a certain range.   5. The drying system according to claim 4, wherein the evaporation pressure control means is detected from the variable capacity compressor, a temperature sensor for detecting the refrigerant temperature at the inlet or outlet of the dehumidifying evaporator, and the temperature sensor. A drying system comprising: a controller that adjusts the capacity of the compressor based on temperature.   5. The drying system according to claim 4, wherein the evaporating pressure control means is detected from the variable capacity compressor, a temperature sensor for detecting the refrigerant temperature at each of the inlet and outlet of the dehumidifying evaporator, and the temperature sensor. A drying system comprising: a controller that adjusts the capacity of the compressor so that a refrigerant temperature difference between two positions falls within a certain range.   7. The drying system according to claim 4, wherein the opening of the expansion valve is adjustable, and the controller adjusts the opening of the expansion valve when the capacity of the compressor is changed. Thus, the drying system is characterized in that the refrigerant flow rate is always appropriately maintained, and the change in the refrigerant flow rate is smoothly adjusted even when the capacity change of the compressor is gradual.   The drying system according to any one of claims 5 to 7, wherein the tank air circulation means is capable of adjusting the air volume, and the controller is configured to circulate the tank air circulation based on a current compressor capacity or a temperature detected by a temperature sensor. A drying system characterized by adjusting the air volume of the means.   The drying system according to any one of claims 5 to 8, further comprising stirring means capable of adjusting the operation speed of the stirring unit for stirring the object to be dried, and the controller is detected by a current compressor capacity or a temperature sensor. A drying system that adjusts the speed of operation of the agitation unit of the agitation unit based on the measured temperature. 10. The drying system according to claim 1, wherein the secondary refrigerant heated by heat exchange with the high-temperature side refrigerant in the heating condenser of the compression refrigeration cycle section is passed through the heating heat exchanger. Heat is removed from the humid air through the cooling heat exchanger from the secondary refrigerant cooled by the heat effect of the low-temperature side refrigerant in the dehumidifying evaporator and the indirect heating component that supplies heat to the object to be dried Comprising at least one indirect component of the indirect cooling component,
Moreover, the indirect component of the compression refrigeration cycle is configured to be separable from the drying system.   The compression refrigeration cycle part which comprises the drying system described in Claim 10. In the operating method of the drying system according to claim 4,
The operation period is divided into a start-up operation period and a dry operation period.
During the start-up period, set the compressor capacity to the maximum,
When the condensation temperature reaches a temperature corresponding to a preset condensation pressure, the rising operation period is shifted to the drying operation period,
During the drying operation period, the condensing temperature is adjusted to be constant by the condensing pressure control means, and the capacity of the compressor is adjusted by the evaporating pressure control means so that the refrigerant temperature corresponding to the refrigerant evaporating pressure is within a certain range. And
Even if the capacity of the compressor is changed to the minimum, the operation is terminated when the refrigerant evaporation pressure further falls below the lower limit of the certain range.
A driving method characterized by that. The operation method of the drying system according to claim 12, wherein when the capacity of the compressor is changed stepwise and the capacity of the compressor is changed, the opening of the expansion valve is adjusted to change the evaporation pressure. A driving method characterized by smoothing.

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