JP4801484B2 - Vacuum drying equipment - Google Patents

Description

The present invention relates to a vacuum drying apparatus for drying the heated in a vacuum material to be dried to the drying cauldron.

  Conventionally, a vacuum drying apparatus has been used as a means for reducing organic waste such as leftover food, food products that have passed the warranty period, and residue in food factories. For example, as shown in Patent Document 1, a general vacuum drying apparatus includes a drying kettle in which an object to be dried is charged, a heating means for heating the inside of the drying kettle, and a vacuum pump for evacuating the inside of the drying kettle. The inside of the kettle is heated in a vacuum state to dry the object to be dried in the drying kettle.

  By the way, as a method of determining the end point of the drying operation by the drying pot of this type of vacuum drying apparatus, there is one that ends the drying operation by a timer, but if there is a difference in the moisture content of the material to be dried before drying, the drying operation is performed. The moisture content of the later dried product becomes unstable, and cannot be sufficiently dried or dried too much.

As another method, a load cell for measuring the weight of the drying kettle is provided, and when the weight of the drying kettle is reduced by a predetermined amount due to water evaporation accompanying drying of the object to be dried, it is judged that the drying kettle has been sufficiently dried. However, if there is a difference in the moisture content of the material to be dried before drying, the moisture content of the material to be dried after drying will not be determined, and the weight of the drying kettle will be reduced. There is also a problem that the cost increases because a load cell to be measured is required.
JP-A-11-337258

The present invention was invented in view of the above-mentioned conventional problems, and even when there is a difference in moisture content before drying, the object to be dried can be reliably dried without excess and deficiency, and the weight of the drying kettle is measured. It is an object of the present invention to provide a vacuum drying apparatus that does not require an expensive instrument such as a load cell.

In order to solve the above problems, a drying apparatus according to claim 1 includes a drying kettle 1 into which an object to be dried 2 is charged, a heating means for heating the inside of the drying kettle 1, and a vacuum pump for making the inside of the drying kettle 1 in a vacuum state. with 8, in a vacuum drying apparatus for drying objects to be dried 2 by heating in a vacuum drying cauldron 1, a condensing means for condensing the steam generated in the drying cauldron 1, it includes a savings engaging portion 6, the reservoir The part 6 communicates with the inside of the drying kettle 1 and receives a condensed tank 22 into which condensed water obtained by the condensing means flows, and is positioned below the cushion tank 22 and connected to the cushion tank 22 via a communication passage 24. A storage tank 23, the vacuum pump 8 is connected to the upper part of the cushion tank 22, a communication valve 25 is provided in the communication path 24, and a drainage valve 34 is provided in the drainage part 30 of the storage tank 23. While the passage valve 25 is opened and the drain valve 34 is closed, the condensed water in the cushion tank 22 flows into the storage tank 23 through the communication passage 24 and is stored, and in this normal state, the storage tank water level detection means When it is detected that the water level of the condensed water in the storage tank 23 is equal to or higher than the predetermined water level, the communication valve 25 is closed and the drain valve 34 is opened to maintain the vacuum state in the drying tank 1 while maintaining the vacuum state in the storage tank 23. A vacuum drying device that switches to a drainage state in which the condensed water is discharged from the drainage portion and returns to the normal state after the lapse of a predetermined time , a cup portion 26 that receives the condensed water flowing into the cushion tank 22 , and a cup portion a cup portion 26 in the water level detection means for detecting the water level of the condensed water in 26, store the other end with connecting one end to the bottom of the cup portion 26 tank 23 A discharge passage 27 connected to the upper, and the discharge valve 28 provided in the discharge passage 27, a control device, control device, the water level of the condensed water in the cup portion 26 every predetermined time t2 during the drying operation It is determined whether or not the water level is equal to or higher than a predetermined water level set in advance. If the water level of the condensed water in the cup portion 26 is higher than the predetermined water level set in advance, the discharge valve 28 is opened to discharge the condensed water in the cup portion 26. empty the cup portion 26 is discharged to the reservoir tank 23 through the passage 27, the condensed water and capable of storing state in the cup portion 26 closes the discharge valve 28 after this, condensation inside the cup portion 26 when the water level of the water is lower than the predetermined water level is characterized in that to terminate the drying operation.

With the above configuration, it is possible to determine that the amount of evaporated water per unit time of the object to be dried 2 has decreased during the drying operation based on the level of the condensed water in the cup portion 26, and thus the drying operation can be terminated. When the dried product 2 is sufficiently dried, the drying operation of the drying pot 1 can be surely terminated. In this case, the end point of the drying operation can be determined without providing a complicated and expensive instrument such as a load cell, and the cost can be reduced. Further, in the vacuum drying apparatus that can switch between the normal state and the drainage state and drain the condensed water in the storage tank 23 while maintaining the vacuum state in the drying kettle 1, the drying operation can be completed with certainty, and the cost can be reduced.

In the drying apparatus of the present invention, even when there is a difference in the moisture content of the material to be dried, the material to be dried can be surely dried without excess or deficiency, and a load cell that measures the weight of the drying vessel is used. Therefore, it is not necessary to provide an expensive instrument and the cost can be reduced.

  Hereinafter, the present invention will be described based on embodiments shown in the accompanying drawings.

  FIG. 1 shows the entire system of the vacuum drying apparatus of the present invention. A drying pot 1 serving as a main body of a vacuum drying apparatus is configured to heat and dry an object to be dried 2 housed therein in a vacuum state. A heating jacket 3 is provided around the drying kettle 1 as a heating means for heating the inside of the drying kettle 1, and heat is supplied to the heating jacket 3 with a heating medium such as hot water or steam to thereby coat the inner wall of the drying kettle 1. It can be heated. When this heat medium is hot water, the heat medium enters the heating jacket 3 as indicated by an arrow A in FIG. 1, and circulates through the heat source unit such that the heat medium exits from the heating jacket 3 as indicated by an arrow B in FIG. It is like that. When the heat medium is steam, the heat medium enters the heating jacket 3 in the direction opposite to the arrow B in FIG. 1, and the heat medium exits from the heating jacket 3 in the direction opposite to the arrow A in FIG.

  The air in the drying kettle 1 is sucked by the vacuum pump 8 through the dust collector 4, the heat exchanger 5, the storage unit 6, and the check valve 7 in order, so that the vacuum state in the drying kettle 1 is maintained. ing. The cooling water cooled by the cooling tower 9 is circulated through the heat exchanger 5 so that the heat exchanger 5 is cooled. When the vacuum pump 8 is driven and the inside of the drying pot 1 is evacuated, the inside of the drying pot 1 is decompressed to about 60 to 100 Torr. The water contained in the material to be dried 2 in the drying kettle 1 is evaporated by heating the drying kettle 1, and the exhaust gas containing evaporated water passes through the dust collector 4 by the suction of the vacuum pump 8 and is cooled and condensed by the heat exchanger 5. As a result, gas-liquid separation is performed, and condensed water accumulates in the reservoir 6 and dry exhaust gas is exhausted to the atmosphere. That is, in this example, the cooling tower 9 and the heat exchanger 5 serving as a condensing part constitute condensing means for condensing water vapor generated in the drying kettle 1 during drying. In addition, when a certain amount of condensed water accumulates in the reservoir 6, it is drained outside the apparatus.

  At the top of the drying kettle 1 is provided an inlet 10 into which an object to be dried 2 made of organic waste containing moisture is introduced. The inlet 10 is airtightly closed by an openable / closable inlet lid 11. Yes. A hopper 12 that receives an object to be dried 2 introduced from an inlet 10 is provided in the upper part of the drying pot 1, and a crusher 13 is disposed at the lower end of the hopper 12. The crusher 13 includes a pair of drive shafts 14 that are rotationally driven by a motor, and a crushing blade 15 that is mounted on each drive shaft 14 so as to be arranged in the axial direction.

  A stirrer 16 is provided in the lower part of the drying pot 1, and drying can be promoted by stirring the material to be dried 2 with the stirrer 16. The stirrer 16 has a blade support shaft 18 projecting radially from a stirring shaft 17 driven by a motor and a blade 19 attached to the tip of the blade support shaft 18. Can be stirred. A dry matter discharge unit 20 for discharging the dried product is provided at the bottom of the drying pot 1.

  When drying the to-be-dried object 2 which consists of organic waste containing a water | moisture content with the vacuum drying apparatus comprised as mentioned above, it carries out as follows by a batch type. The material to be dried 2 is charged from the charging port 10 to the hopper 12 in the drying kettle 1, and the heating chamber 3 of the drying kettle 1 is supplied with a heating medium with the charging port lid 11 closed to heat the drying kettle 1. At the same time, the vacuum pump 8 is driven to evacuate the inside of the drying kettle 1, the crusher 13 is driven, and the stirrer 16 is driven. Then, the to-be-dried object 2 thrown into the hopper 12 is crushed by the crusher 13 and supplied to the lower part in the drying pot 1. The to-be-dried object 2 dropped to the lower part in the drying pot 1 is dried in the atmosphere of the drying pot 1 while being stirred by the stirrer 16. For example, it is dried so that the water content is 60% to 10%. The dried product is finely granulated, and the dried product is discharged from the discharge unit 20, thereby completing the drying operation.

  Here, the structure of the reservoir 6 into which the condensed water obtained by the heat exchanger 5 flows will be described in detail.

  As shown in FIG. 2, the storage unit 6 includes a cushion tank 22 into which condensed water obtained by the heat exchanger 5 flows, and a storage tank 23 that is positioned below the cushion tank 22 and connected to the cushion tank 22. The above-described vacuum pump 8 is connected to the upper end portion of the cushion tank 22.

The bottom end of the cushion tank 22 is connected to the upper end of the communication path 24 whose lower end is connected to the upper end of the storage tank 23. The communication passage 24 is provided with a communication valve 25 composed of an electromagnetic on-off valve. By opening the communication valve 25, the condensed water flowing into the cushion tank 22 can be discharged to the storage tank 23 via the communication passage 24. A cup portion 26 that directly receives condensed water flowing from the heat exchanger 5 side is provided at a location different from the communication passage 24 at the bottom portion in the cushion tank 22, and a lower end is provided at the bottom portion of the cup portion 26 at the storage tank 23. The upper end of the discharge flow path 27 connected to the upper end of each is connected. The discharge passage 27 is provided with a discharge valve 28 composed of an electromagnetic opening / closing valve. By closing the discharge valve 28, the condensed water flowing from the heat exchanger 5 side can be stored in the cup portion 26, and the discharge valve 28 is provided. By opening, the condensed water in the cup part 26 can be flowed to the storage tank 23 via the discharge flow path 27. Further, the cushion tank 22 is provided with a water level sensor 29 for detecting whether or not the water level in the cup part 26 is equal to or higher than a predetermined water level as a water level detecting means in the cup part for detecting the water level in the cup part 26.

On the other hand, a drainage part 30 consisting of a drainage outlet for discharging condensed water in the storage tank 23 to the outside is provided at the bottom of the storage tank 23, and a drainage valve 34 consisting of an electromagnetic on-off valve is provided in the drainage part 30. . At the upper end of the storage tank 23 is provided an air release portion 31 that is an open port that opens the inside of the storage tank 23 to the atmosphere, and the air release portion 31 is provided with an air release valve 32 that is an electromagnetic on-off valve. Further, the storage tank 23 is a water level that detects whether or not the water level in the storage tank 23 is equal to or higher than a predetermined water level as a water level detection means in the storage tank that detects the water level of the condensed water stored in the storage tank 23. A sensor 33 is provided.

  The communication valve 25 and the discharge valve 28 of the cushion tank 22 and the discharge valve 28 and the air release valve 32 of the storage tank 23 are controlled as shown below by a control device (not shown) provided in the vacuum drying device. FIG. 3 is a time chart during the drying operation.

  When the control device drives the heating jacket 3, the vacuum pump 8, the crusher 13, and the stirrer 16 to start the drying operation of the drying pot 1, the communication valve 25 is opened and the discharge valve 28, the drain valve 34, and the atmosphere are opened. The valve 32 is closed and in a normal state. As a result, the air in the drying kettle 1 is sucked by the vacuum pump 8 through the cushion tank 22 and the drying kettle 1 is in a vacuum state. At this time, the condensed water obtained by the heat exchanger 5 during the drying operation of the drying pot 1 flows into the cup portion 26 of the cushion tank 22 and is stored in the cup portion 26 as indicated by the white arrow in FIG. After the cup portion 26 is fully filled, the cup portion 26 overflows and flows into the storage tank 23 from the bottom of the cushion tank 22 via the communication path 24 and is stored. In this normal state, since the communication valve 25 is open and the drain valve 34 and the air release valve 32 are closed, the inside of the storage tank 23 is also evacuated to a vacuum state.

  Further, when the control device detects that the water level of the condensed water in the storage tank 23 is equal to or higher than the predetermined water level by the water level sensor 33 of the storage tank 23 in the normal state during the drying operation of the drying pot 1, the communication device communicates. The valve 25 and the discharge valve 28 are closed, and then the atmosphere release valve 32 is opened. Thereafter, the drain valve 34 is opened, and the drainage state is set. As a result, the air in the drying tank 1 remains sucked by the vacuum pump 8 via the cushion tank 22 (that is, the drying tank 1 side is in a sealed state and the vacuum is maintained), and the storage tank 23 is opened to the atmosphere. The condensed water stored in the storage tank 23 after being released to the atmosphere from the section 31 and breaking the vacuum in the storage tank 23 is drained to the outside through the drainage section 30 and the storage tank 23 is emptied. At this time, since the communication valve 25 is closed, the condensed water flowing into the cushion tank 22 from the heat exchanger 5 side is temporarily stored in the cushion tank 22 and does not flow to the storage tank 23 side. Thereafter, the control device closes the drain valve 34 and the air release valve 32 when a predetermined time has elapsed, and then opens the communication valve 25, thereby returning to the normal state. That is, the control device performs the drying operation by alternately repeating the normal state and the drainage state.

The control unit 35 also, the drying Oite during the drying operation of the kettle 1, when the generation amount per predetermined time of the condensed water becomes less than the amount set in advance, a heating jacket 3, the vacuum pump 8, crusher 13 Then, the operation of the stirrer 16 and the like is stopped and the drying operation is terminated.

  Specifically, the control device first sets the discharge valve 28 as an initial period during which the water of the object to be dried 2 is difficult to evaporate until a predetermined time t1 (1 to 2 hours) elapses from the start of the drying operation of the drying pot 1. Keep closed. The amount of condensed water per unit time generated from the material to be dried 2 at the end of the initial period is commensurate with the amount of condensed water generated per predetermined time t2 when determining the end of the drying operation as described later. It is larger than the amount of condensed water generated per unit time. Then, the water level sensor 29 determines whether or not the water level of the condensed water in the cup portion 26 is equal to or higher than a predetermined water level set in advance by the water level sensor 29 every predetermined time t2 (30 minutes) from the end of the initial period. If it is determined that the water level of the condensed water in the cup portion 26 is equal to or higher than a predetermined water level set in advance, the discharge valve 28 is opened to allow the condensed water in the cup portion 26 to pass through the discharge passage 27 to the storage tank 23. Then, the cup portion 26 is emptied, and then the discharge valve 28 is closed so that condensed water can be stored in the cup portion 26. Moreover, when the water level of the condensed water in the cup part 26 is lower than a predetermined water level by this determination, the operation of the heating jacket 3 and the vacuum pump 8 is stopped and the drying operation is terminated. According to the above determination, the opening operation of the discharge valve 28 performed when the water level of the condensed water in the cup portion 26 is equal to or higher than a predetermined water level set in advance is that the vacuum drying device is in the drainage state and the discharge valve 28 is closed It is invalid when it is in the state, and the discharge valve 28 is opened for a predetermined time at the next determination or at the next normal state recovery.

  Thus, in the present invention, the drying operation is terminated when the amount of condensed water discharged by the control device during the drying operation of the object to be dried 2 per predetermined time is less than the preset amount. The effect is obtained. That is, when the object to be dried 2 is dried, the amount of water evaporated from the object to be dried 2 per unit time usually decreases as the moisture content of the object to be dried 2 decreases. When the amount of evaporating water decreases, it can be determined that the material to be dried 2 is sufficiently dried. In other words, in the present invention, the drying operation is terminated when the amount of condensed water obtained by the condensing means during the drying operation per predetermined time is less than a preset amount. Even when there is a difference in the moisture content of the dried product 2 before drying, the dried product 2 can be sufficiently dried without being dried too much. Further, according to the present invention, it is possible to determine that the amount of evaporated water per unit time of the object to be dried 2 is reduced based on the water level of the condensed water in the cup portion 26, and the load cell-like structure is complicated and expensive. It is possible to determine the end point of the drying operation without providing the in the drying pot, and to reduce the cost.

It is a conceptual diagram which shows the whole system of an example of embodiment of the vacuum drying apparatus of this invention. It is explanatory drawing of a storage part same as the above. It is a time chart same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Drying pot 2 To-be-dried object 8 Vacuum pump 22 Cushion tank 23 Storage tank 24 Communication path 25 Communication valve 26 Cup part 27 Discharge flow path 30 Drain part

Claims (1)

A drying kettle into which the material to be dried is put, a heating means for heating the inside of the drying kettle, and a vacuum pump for evacuating the inside of the drying kettle are provided. The inside of the drying kettle is heated in a vacuum state to dry the material to be dried. In vacuum drying equipment,
A condensing means for condensing the steam generated in the drying kiln, with a savings engaging portion, the reservoir portion, and a cushion tank condensate obtained by condensing means communicates with the drying kiln flows, than the cushion tank A storage tank that is located below and is connected to the cushion tank via a communication path is connected. The vacuum pump is connected to the upper part of the cushion tank, a communication valve is provided in the communication path, and a drain valve is provided in the drainage section of the storage tank. Provided,
During the drying operation, the communication valve is opened and the drain valve is closed so that the condensed water in the cushion tank flows into the storage tank through the communication path to be stored, and in this normal state, the storage tank water level detection means When it is detected that the water level of the condensed water in the storage tank has reached the specified level or higher, the condensate water in the storage tank is drained while closing the communication valve and opening the drain valve to maintain the vacuum state in the drying tank. A vacuum drying device that switches to a drained state that is discharged from the part and returns to the normal state after the predetermined time has elapsed,
A cup that receives the condensed water flowing into the cushion tank , a water level detecting means for detecting the level of condensed water in the cup , and one end connected to the bottom of the cup and the other connected to the top of the storage tank a discharge passage which is either a discharge valve provided in the discharge passage, a control device, control device, the water level of the condensed water in the cup portion every predetermined time during the drying operation is a predetermined level or more set in advance If the water level of the condensed water in the cup part is equal to or higher than a predetermined water level set in advance, the discharge valve is opened and the condensed water in the cup part is discharged to the storage tank via the discharge flow path, and the inside of the cup part is discharged. sky and then, the feature is intended Thereafter the condensed water and capable of storing state in the cup portion closes the discharge valve, when the water level of the condensed water in the cup portion is lower than the predetermined water level to end the drying operation That vacuum drying equipment.

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