JPH0972661A - Dryer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a direct heating type drying device capable of dry-treating with high efficiency. SOLUTION: A vacuum drying device comprises largely a drying vessel 11, which houses substances to be dried, such as garbage, a cold heat generation device 12 comprising a condenser 35, which is connected to the drying vessel 11 by way of a steam discharge pipeline 79, a vacuum pump 81, which is connected to the upper part of the condenser 35 by way of an exhaust pipeline 83 and an auxiliary heating device in which hot water is circulated, centering on a pump 59. The refrigerants supplied by way of a refrigerant pipeline 21a heat the substances in the drying vessel 11 by passing through a refrigerant coil 23 in a jacket 13 formed in the lower area of the drying vessel 11. When the temperature of the refrigerants in the refrigerant pipeline 21d on the outlet side of the condenser 25 is low, a solenoid valve 41 is closed so that the refrigerants may flow to an expansion tank, which serves as a refrigerant heater as well by way of a feed branch pipeline 55a, a refrigerant coil 57 and a return branch pipeline 55b where the refrigerants are heated and adapted to flow into a compressor 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drying device, and more particularly, to a vacuum drying device for accommodating and heating an object to be dried such as kitchen waste, and evaporating the moisture to dry the object.

[0002]

2. Description of the Related Art FIG. 2 is a diagram showing a schematic configuration of a conventional direct heating type vacuum drying device disclosed in Japanese Patent Laid-Open No. 5-118753. Referring to the drawings, this vacuum drying apparatus is mainly provided with a drying container 11 for storing food waste such as kitchen waste.
Then, the moisture evaporated from the garbage is introduced to condense it, and the condenser 35 for returning it to water is sucked and degassed from the drying container 11 via the condenser 35, and the water generated in the condenser 35 is forced. Vacuum pump 81 which is a means for exhausting and draining to the
And a heat pump D for supplying warm heat for drying the kitchen waste in the drying container 11 and cold heat for condensing water in the condenser 35 during the drying operation. And the generated cold heat from the refrigerant pipe 21a of the heat pump D to the drying container 11 and the refrigerant pipe 21.
It is adapted to be supplied to the condenser 35 from c.

The drying container 11 is constructed as a pressure-tight sealed container, and has an input port 101 for inputting wet or damp kitchen waste before processing, and an output port 103 for taking out the dried material after the drying processing. The steam discharge pipe 79 is taken out from the upper part. The steam discharge pipe 79 is taken out from the upper surface of the drying container 11 and formed in an inverted U shape, and its end is connected to the condenser 35. A discharge pipe 51 is connected to the bottom of the condenser 35, and the check valve 105 is connected to the discharge pipe 51.
And a vacuum pump 81 is installed with the former arranged on the upstream side.

On the other hand, the heat pump D is one in which a compressor 19 and a capillary tube 107 are arranged in refrigerant pipes 21a to 21d which are closed pipes in which a refrigerant such as CFC is sealed.
The pipe is configured such that the direction in which the refrigerant pumped by the compressor 19 passes through the capillary tube 107 can be switched between forward and reverse by a four-way valve 109. In this heat pump D, the heat exchanger 201 is arranged along the lower surface of the bottom plate of the drying container 11 in a meandering or spiral shape, and the spiral pipe 37 is connected to the condenser 3
It is inserted in 5 to form a coil shape.

In the figure, the stirrer 15 has a rotating shaft 203.
Is rotated by a motor (not shown). The lower part of the drying container 11 is covered with a heat insulating material 205. In this way, in the vacuum dryer, the compressor 19 of the heat pump D is driven and the four-way valve 1
09 and the three-way valve 207 are operated to configure the refrigerant tubes 21a to 21d so that the refrigerant flows from the compressor 19 in the order of the heat exchanger 201, the capillary tube 107, the spiral tube 37, and the compressor 19. Due to the passage resistance of the tube 107 portion, the heat exchanger 201 in the flow direction of the refrigerant is
Becomes high in the pipeline between the compressor 19 and the capillary tube 107, and the temperature of the pipeline rises due to condensation of the refrigerant, and a low pressure occurs in the pipeline between the capillary tube 107 including the spiral tube 37 and the compressor 19. As a result, the refrigerant evaporates and the temperature drops.

Therefore, the drying container 11 is heated via the heat exchanger 201, and the condenser 35 is cooled via the spiral tube 37. Therefore, if an object to be dried such as kitchen waste is put into the drying container 11 and sealed, the vacuum pump 81 is driven, and the inside of the drying container 11 is depressurized until the boiling point of water becomes equal to the outside air temperature. Since the cooked kitchen waste is warmed by the heating energy of the heat exchanger 201 to evaporate the water content, the drying container 1
1, the steam pressure inside 1 increases, and the steam inside the drying container 11 works in conjunction with the operation of the vacuum pump 81.
Flow to 9. Then, this steam flows into the condenser 35 and the heat is recovered by the cold heat of the spiral tube 37, so that the steam is condensed and the volume becomes small, and is discharged as drain water through the vacuum pump 81.

In this way, the evaporation in the drying container 11 and the condensation in the condenser 35 continuously occur, and the garbage, which is the object to be dried, is dried.

[0008]

However, the conventional direct heating type drying apparatus as described above is insufficient for shortening the time required for the entire drying process. That is, in the conventional direct-heat type drying device, the refrigerant supplied with the heat through the refrigerant pipe 21a is directly dried through the heat exchanger 201 in which the pipe is welded to the bottom surface of the drying container 11. 1
Since the bottom plate of No. 1 is heated, the heat transfer area cannot be said to be sufficient. Further, since the specific heat of the refrigerant is small, the insufficient heat transfer area further lowers the heat transfer efficiency.

FIG. 3 is a diagram showing changes in the temperature of the refrigerant and the material to be dried from the start of operation until the steady state is reached. Referring to the figure, the horizontal axis represents elapsed time, and the vertical axis represents temperature, showing changes in temperature of the high-pressure side refrigerant that imparts heat and the object to be treated. In the conventional direct-heating type drying device, it takes time for the high-pressure side refrigerant to reach a predetermined temperature as indicated by the broken line, and accordingly, the temperature of the object to be treated becomes steady and a considerable amount of steam is generated until it reaches a predetermined amount. Takes time.
Desirably, if the time to reach a steady state can be shortened as indicated by the solid line, the time required for the drying process can be shortened overall.

When the drying treatment of the material to be dried progresses to reach the gelatinization and curing area and the stirring effect is lowered, the amount of steam generated generally decreases, but the amount of steam generated suddenly increases depending on the stirring state. Sometimes. Therefore, even if the steam generation amount is reduced as a whole, it is not possible to reduce the heat generation amount commensurate with the steam generation amount, so that the efficient operation cannot be performed. Furthermore, the evaporation amount is drastically reduced at the end of the drying process and the condenser 35
In the case where the consumption amount of cold heat is reduced in, the refrigerant in the refrigerant pipe 21d may return in a liquefied state. When the refrigerant flows into the compressor 19 in this state, an excessive load is applied to the compressor 19, which causes a failure.

An object of the present invention is to provide a drying device which is made in order to solve such a problem and which enables an efficient drying process. In addition to the object of the invention described in claim 1, it is an object of the invention to provide a drying device that accelerates the rise of warm heat to a predetermined amount at the start of operation.

According to the invention of claim 3, in addition to the object of the invention of claim 2, even when the required amount of cold heat is reduced,
An object of the present invention is to provide a drying device that does not apply an excessive load to the cold / heat generating device.

[0013]

In order to achieve the above-mentioned object, the invention according to claim 1 of the present invention is characterized in that a cooling and heating device and a jacket portion are connected so that a refrigerant circulates, It is characterized in that the heat generated by the heat generator is applied to the drying container through the jacket portion in which the liquid is sealed.

In addition to the configuration of the invention described in claim 1, the invention described in claim 2 is provided in a liquid circulation circuit which is connected to the jacket portion and circulates the liquid through the jacket portion, and in the circulation circuit. And heating means for heating the circulating liquid. Further, in addition to the configuration of the invention according to claim 2, the invention according to claim 3 uses the at least a part of the heated liquid provided in the liquid circulation circuit, to cool and circulate the cold heat from the condenser. It is characterized by further comprising a refrigerant heating means for heating the refrigerant in the circuit.

[0015]

As described above, according to the first aspect of the present invention, the heat generated by the cold heat generator is applied to the drying container through the jacket portion. The efficiency of transfer of warm heat to the drying container is improved. In addition to the effect of the invention according to claim 1, the invention according to claim 2 further comprises a heating means for heating the liquid circulating in the jacket portion, so that the application of the heat to the steady amount at the start of the operation can be improved. The raising time can be shortened.

In addition to the effect of the invention described in claim 2, since the invention described in claim 3 further comprises a refrigerant heating means for heating the refrigerant in the cold heat circulation circuit returning from the condenser, the required amount of cold heat is required. Even when the temperature decreases, the cold / heat generating device is not overloaded.

[0017]

1 is a diagram showing the structure of a vacuum drying apparatus according to an embodiment of the present invention. Referring to the drawing, the vacuum drying apparatus is mainly composed of a drying container 11 in which an object to be dried such as kitchen waste is stored, and a refrigerant tube 21a to 21d around which a refrigerant is circulated around the compressor 19 to generate cold heat. The device 12, the condenser 35 connected to the drying container 11 via the vapor discharge pipe 79, the vacuum pump 81 connected to the upper portion of the condenser 35 via the exhaust pipe 83, and the hot water around the pump 59 It is composed of a circulating auxiliary heating device 14.

The cool / heat generator 12 includes a compressor 19 for compressing and liquefying a refrigerant such as freon from a vaporized state, refrigerant pipes 21a to 21d for circulating the refrigerant, and a drying container 11 connected to the refrigerant pipe 21a. The refrigerant coil 23 installed in the jacket portion 13 that covers the lower portion and the lower portion of the side surface, the air-cooled condenser 25 connected to the refrigerant pipe 21b, and the outlet side of the air-cooled condenser 25 and the condenser 35 are connected. Refrigerant pipe 2
1c, a spiral pipe 37 connected to the refrigerant pipe 21c and spirally arranged in the condenser 35, and a refrigerant pipe connected to the spiral pipe 37 and connected between the condenser 35 and the compressor 19. 21d. A condensing pressure adjusting valve 27 for adjusting the pressure of the refrigerant returned from the air cooling condenser 25 to a predetermined pressure, a solenoid valve 31, and an expansion valve 33 are connected to the refrigerant pipe 21c. Further, an electromagnetic valve 41 whose opening / closing is controlled via a temperature controller 39 by the temperature on the outlet side of the condenser 35 is connected to the refrigerant pipe 21d. It should be noted that the refrigerant pipe 21d is branched at the node N1 to be an expansion tank / refrigerant superheater 53.
Branch pipe 55a and expansion tank / refrigerant superheater 5
3 and the return branch pipe 55b that merges with the refrigerant pipe 21d at the node N2 through the refrigerant coil 57 inside. An electromagnetic valve 85 is connected to the return branch pipe 55b. Further, the nodes N3 and N4 before and after the compressor 19 are provided.
A bypass pipe 18 is provided between the bypass pipe 18 and
A vapor pressure adjusting valve 43 is attached to the compressor 19 for bypassing a part of the refrigerant to the compressor 19 according to the pressure of the refrigerant.

On the other hand, the auxiliary heating device 14 includes a pump 59 for circulating water, a forward hot water pipe 61a connected between the pump 59 and the jacket portion 13 formed in the lower portion of the drying container 11, and the outlet of the jacket portion 13. Expansion tank / refrigerant superheater 53 connected to the return hot water pipe 61b connected between the side and the pump 59 and the branch hot water pipe 73 branched from the node N7 of the forward hot water pipe 61a, the node N5 and the node N6 of the hot water pipe 61a. By-pass pipe 1 connected to bypass and
And 6.

The branch hot water pipe 73 penetrates through the solenoid valve 75 into the expansion tank / refrigerant superheater 53, and the tip of the branch hot water pipe 73 can discharge water in a spray form to the refrigerant coil 57 through which the refrigerant passes. It has a shape that allows it. The expansion tank / refrigerant superheater 53 has a structure capable of storing about half of the circulating water therein. The bypass pipe 16 has a solenoid valve 63 whose opening and closing is controlled by a temperature on the outlet side of the jacket portion 13 from the upstream side of the bypass pipe 16 and a pump 65 for ensuring the amount of water passing through the bypass pipe 16 and a flow rate. A switch 67 and an auxiliary heater 69 for heating the water passing through it by a gas burner or the like are attached.

A discharge pipe 51 connected to the lower portion of the condenser 35
The opening / closing is controlled by a pump 45 for discharging the condensed water stored in the condenser 35 each time a predetermined amount is discharged, and a water level detector 47 detecting the water level of the condensed water in the condenser 35. A solenoid valve 49 is attached. Next, the operation of this vacuum dryer will be described.

The material to be dried is housed inside the drying container 11,
When the drying process is started, the cool / heat generating device 12 operates. That is, the compressor 19 operates and the refrigerant flows into the refrigerant pipe 21a,
Refrigerant coil 23, air-cooled condenser 25, refrigerant pipe 21c,
It circulates through the spiral pipe 37 and the refrigerant pipe 21d. on the other hand,
The auxiliary heating device 14 also operates together. That is, the pump 59
Is activated, water flows out, and the hot water pipe 61a and the jacket portion 13
It circulates through the internal and return hot water pipes 61b. Thus, the refrigerant to which the high temperature and high pressure are applied by the operation of the compressor 19 passes through the refrigerant coil 23 and heats the bottom of the drying container 11 through the water in the jacket 13. Therefore,
Since the heat given to the refrigerant is absorbed by the water in the jacket portion 13 without waste, the heat can be efficiently used.

By the way, when the operation is started, the refrigerant does not reach the predetermined temperature immediately as shown in FIG. Moreover, the temperature of the circulating water remains low even with the auxiliary heating device 14. Therefore, the temperature of the water on the outlet side of the jacket portion 13 becomes equal to or lower than the predetermined temperature, and the temperature regulator 71 causes the solenoid valve 63 to “open”.
Then, the pump 65 also operates. Therefore, the water circulating in the outgoing hot water pipe 61a and the returning hot water pipe 61b is not supplied to the node N5.
A large part of it branches off and passes through the bypass pipe 16. Then, it is heated in the auxiliary heater 69 to become warm water of a predetermined temperature, and the jacket portion 13 passes through the node N6.
Flows in and contributes to the heating of the material to be dried in the drying container 11. Further, since this hot water also heats the refrigerant passing through it through the refrigerant coil 23 at the start of operation, the time required to reach the predetermined temperature of the refrigerant can be shortened. In this way, as shown by the solid line in FIG. 3, the time from the start of operation to the steady operation is shortened, the temperature rise of the material to be dried is accelerated, and the drying processing time as a whole is shortened.

The high-temperature, high-pressure refrigerant liquefied by the compressor 19 returns to the air-cooling condenser 25 through the refrigerant pipe 21b, is air-cooled there to lower the temperature, and is adjusted to a predetermined pressure through the condensing pressure adjusting valve 27 to receive the liquid. It is stored in the tank 29. Here, when the operation is in a low temperature such as in winter, the refrigerant may be condensed even when the fan of the air-cooling condenser 25 is close to the stopped state. Therefore, the number of rotations of the fan of the air-cooling condenser 25 is continuously changed in order to cope with such a climate change and the temperature change of the outside air. As a result, the condensation pressure control valve 27 appropriately controls the condensation pressure of the refrigerant. Further, since it is possible to sufficiently cope with the load fluctuation due to the material to be dried in the drying container 11, the condensation temperature of the refrigerant can be controlled to a desired temperature. The refrigerant stored in the liquid receiving tank 29 is vaporized in the expansion valve 33 with the electromagnetic valve 31 being “open”, and the temperature thereof is lowered. Then, the low-temperature refrigerant cools and condenses the steam flowing into the condenser 35 through the steam discharge pipe 79 while passing through the spiral tube 37 of the condenser 35. The condensed water is stored in the lower part of the condenser 35, and when a predetermined amount is accumulated, the fact is detected by the water level detector 47, and the pump 45 is operated. Then, open the solenoid valve 49.
As a result, the condensed water is discharged to the outside.

During normal operation, the temperature of the refrigerant returning through the refrigerant pipe 21d rises above a predetermined temperature because heat is exchanged in the condenser 35. However, since the amount of steam flowing into the condenser 35 through the steam discharge pipe 79 is small at the start of operation, the cold heat of the refrigerant is not sufficiently used in the condenser 35. Therefore, the temperature of the refrigerant on the outlet side of the condenser 35 may be equal to or lower than a predetermined temperature, and in some cases, the liquefied state may remain. In this state, the compressor 19
If you return it to, it will put an excessive load on the compressor 19,
Not preferred. Therefore, a part of the refrigerant having a considerably increased pressure returning through the refrigerant pipe 21d is bypassed to the outlet side refrigerant pipe 21a of the compressor 19 via the vapor pressure adjusting valve 43 of the bypass pipe 18. In this way, the load on the compressor 19 is reduced and the power consumption is reduced. It is preferable to adjust the pressure adjusting valve 43 so that the bypass amount becomes 40 to 50% at maximum in consideration of load fluctuation.

However, even if the refrigerant is partially bypassed in this way, the temperature of the refrigerant at the outlet of the condenser 35 may still be low depending on the amount of generated steam. On the other hand, repeating ON / OFF of the compressor 19 is not so preferable. Therefore, when the temperature on the outlet side of the condenser 35 is equal to or lower than the predetermined temperature, the solenoid valve 41 is closed and the solenoid valve 85 is closed.
Is "opened" to allow the returned refrigerant to flow into the refrigerant coil 57 of the expansion tank / refrigerant superheater 53 through the outward branch pipe 55a.

On the other hand, hot water is circulated in the auxiliary heating device 14, and a part of the hot water diverges as necessary to the branch hot water pipe 73.
Is sprayed toward the refrigerant coil 57 from above in the expansion tank / refrigerant superheater 53. Therefore, the temperature of the low-temperature refrigerant in the refrigerant coil 57 rises there, and the return branch pipe 55b and the solenoid valve 85 are completely vaporized.
And returns to the refrigerant pipe 21d. In this way, the expansion tank / refrigerant superheater 53 serves as an expansion tank for the circulation system of the hot water of the auxiliary heating device 14, and when the temperature of the refrigerant before returning to the compressor 19 is equal to or lower than a predetermined temperature, it is completely heated. It also serves to overheat the refrigerant to bring it into a proper vaporized state.

In the above embodiment, a cascade method is adopted in which a part of the refrigerant coil 57 in the expansion tank / refrigerant superheater 53 is filled with hot water, and the hot water is sprayed onto the refrigerant coil 57 exposed from the upper portion. However, instead of this, a water bath system may be used in which the refrigerant coil 57 is completely immersed in hot water and the hot water is simply circulated through the expansion tank / refrigerant superheater 53.

When a steady state is reached after a lapse of a predetermined time from the start of operation, the heat generated by the cold heat generator 12
The cold heat and the evaporation amount of the material to be dried are in a balanced state. At that time, since the adjustment of hot heat or cold heat is not necessary, the solenoid valve 63 is "closed", and the auxiliary heating of the hot water by the auxiliary heater 69 is unnecessary. Next, when the drying process progresses and the material to be dried reaches the gelatinization and curing area, the amount of steam generated decreases, and correspondingly, the amount of heat required for evaporation and the amount of cold required for condensation of steam are reduced. It will be good. However, due to the sudden generation of steam depending on the stirring state, there is excess cold heat,
There is a situation where excess heat is left. When the cold heat remains, the cold heat is released by passing the refrigerant through the expansion tank / refrigerant superheater 53 as described above, and when the hot heat remains, the air-cooling condenser 25 releases the warm heat. The load fluctuation in the drying container 11 is dealt with.

When the drying process further progresses to the almost end state, the load fluctuation in the drying container 11 hardly occurs, and the required amount of cold heat and warm heat is greatly reduced. In that case, the refrigerant pipe 2
A part of the refrigerant whose pressure has returned considerably through 1d is considerably bypassed to the refrigerant pipe 21a on the outlet side of the compressor 19 via the vapor pressure adjusting valve 43 of the bypass pipe 18. In this way, the load on the compressor 19 is reduced and the power consumption is reduced. When the bypass using the bypass pipe 18 alone is insufficient, the expansion tank / refrigerant heater 53 is used to adjust the load of cold heat and warm heat as described above.

Although the present invention is applied to the vacuum drying device in the above-mentioned embodiments, it goes without saying that the idea of the present invention can be similarly applied to a drying device which performs drying without using a vacuum pump. Yes.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a vacuum drying apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a conventional vacuum drying device.

FIG. 3 is a diagram showing changes in the temperature increase of the refrigerant and the temperature increase of the material to be dried at the start of operation in the vacuum drying apparatus of the present invention and the related art.

[Explanation of symbols]

 11 Drying Container 12 Cooling / Heat Generating Device 13 Jacket 14 Auxiliary Heating Device 21a-d Refrigerant Pipe 35 Condenser 53 Expansion Tank / Refrigerant Heater 57 Refrigerant Coil 69 Auxiliary Heater Incidentally, the same reference numerals in each drawing indicate the same or corresponding parts. Show.

Claims (3)

[Claims] 1. A direct-heating type drying device, comprising: a drying container for containing an object to be dried such as kitchen waste; and a condenser connected to the drying container for discharging vapor generated in the drying container. A cold-heat generating device that generates hot and cold heat by compressing and expanding a refrigerant; a jacket portion that is provided so as to cover a lower portion of the drying container and in which a liquid is sealed; and the cold-heat generating device. A heat circulation circuit that connects the inside of the jacket portion so that the refrigerant circulates, and applies the heat generated by the cold heat generator to the drying container via the liquid of the jacket portion, A drying device, comprising: a generator and the condenser connected so that the refrigerant circulates; and a cold heat circulation circuit that applies the cold heat generated by the cold heat generator to the condenser. 2. A liquid circulation circuit that is connected to the jacket portion and circulates the liquid through the jacket portion; and a heating unit that is provided in the circulation circuit and that heats the circulating liquid. The drying device according to claim 1. 3. A refrigerant heating means provided in the liquid circulation circuit, for heating the refrigerant in the cold heat circulation circuit returning from the condenser, using at least a part of the heated liquid. The drying device according to claim 2.