JP2008196759A - Drier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To carry out drying at a low temperature without causing thermal denaturation of an object to be dried, while suppressing developing of bacteria. <P>SOLUTION: The drier is provided with: a drying chamber 3 housing the object 2 to be dried; a decompressing means 4 for decompressing a drying chamber 3 interior; a circulating means 5 for circulating steam in the drying chamber; a steam overheating means 6 for overheating the steam in the drying chamber 3; a circulation path 7 formed such that the steam overheated by the steam overheating means 6 is circulated between the object 3 and the steam overheating means 6 by the circulating means 5; and a control means 8 for controlling the decompressing means 4 to control a pressure in the drying chamber 3 at a set pressure, and controlling the steam overheating means 6 to control an overheated steam temperature at a set temperature of 30°C or lower, and a freezing temperature of the object 3 or higher by the steam overheating means 6 and carrying out a drying process. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a drying apparatus for drying an object to be dried with superheated steam.

  As this seed drying apparatus, the one described in Patent Document 1 is known. This drying device is composed of a pressure vessel that accommodates an object to be dried, a circulation pipe that circulates superheated steam, and a steam superheater and a circulation device that are provided in the circulation pipe. Then, while the superheated steam is circulated through the pressure vessel via the circulation pipe, the inside of the pressure vessel is maintained at a constant pressure by the decompression pump.

JP 2006-17353 A

  However, since the drying apparatus of Patent Document 1 has a superheated steam temperature of 120 ° C., drying of an object to be dried which is vulnerable to heat denaturation such as fish causes heat denaturation of the object to be dried. Also, since the circulation pipe, steam superheater and circulation device are installed outside the pressure vessel, air leaks into the interior due to air leaks, which may reduce the drying speed and saturate before starting drying. An amount of heat for heating to a temperature higher than the steam temperature is required. Moreover, since the contact area with outside air is large, there exists a subject that heat loss is large.

  The main problem to be solved by the present invention is to enable drying at a low temperature without causing the thermal denaturation of the material to be dried while suppressing the propagation of various bacteria. In addition, as a secondary matter, it is an object to reduce air leakage with high drying efficiency and to reduce heat loss.

  The present invention has been made in order to solve the above-mentioned problems. The invention according to claim 1 is directed to a drying chamber that accommodates an object to be dried, a decompression unit that depressurizes the drying chamber, and steam in the drying chamber. Circulating means, steam superheating means for superheating steam in the drying chamber, and steam superheated by the steam superheating means so that the circulation means circulates between the material to be dried and the steam superheating means. And the pressure reducing means to control the pressure in the drying chamber to a set pressure, the steam superheating means to control the superheated steam temperature at 30 ° C. or less by the steam superheating means, Control means for performing a drying process by controlling to a set temperature equal to or higher than the freezing temperature of the object to be dried is provided.

  According to invention of Claim 1, a to-be-dried object can be dried at low temperature for a short time, suppressing the propagation of miscellaneous bacteria.

  A second aspect of the present invention includes the heat retaining means for the inner wall temperature of the drying chamber according to the first aspect, and the control means controls the heat retaining means so that the inner wall temperature of the drying chamber is equal to or higher than the saturation temperature of the steam. It is characterized in that the drying process is performed while being held at the same temperature.

  According to the second aspect of the present invention, in addition to the effect of the first aspect of the invention, it is possible to prevent condensation of steam in the drying chamber wall, and to efficiently perform drying with superheated steam.

  According to a third aspect of the present invention, in the first or second aspect, the circulation means and the circulation path are provided in the drying chamber.

  According to invention of Claim 3, in addition to the effect by the invention of Claim 1 or Claim 2, since the circulation path, the circulation means, and the steam superheater are provided in the drying chamber, It is possible to increase the drying efficiency by reducing air leakage, and to provide a drying device that has a small heat radiation area and a small heat loss.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the steam generating means is provided, and the control means operates the steam generating means and the pressure reducing means before the drying step to operate the steam generating means. The air in the drying chamber is excluded by the generated steam.

  According to the invention described in claim 4, in addition to the effects of the invention described in claims 1-3, the air in the drying chamber can be excluded before the drying step, and after the air is exhausted, Since the superheated steam can be generated by the steam superheating means using the steam filled in the drying chamber, it is possible to efficiently dry the material to be dried at the initial stage of the drying process in which evaporation from the material to be dried is small. Play.

  According to this invention, it is possible to dry an object to be dried at a low temperature in a short time while suppressing the propagation of various bacteria.

  Next, an embodiment of the drying apparatus of the present invention will be described. The embodiment of the present invention is preferably implemented in a drying apparatus that dries an object to be dried such as a fish vulnerable to heat denaturation in an oxygen-free state by superheated steam.

  Before describing embodiments of the present invention, terms used in the present application will be described. “Drying efficiency” means the proportion of the total heat supplied to the system that was used for water evaporation of the material to be dried. Means the percentage of time.

(Embodiment 1)
The first embodiment will be specifically described. The first embodiment includes a drying chamber that accommodates an object to be dried, a decompression unit that depressurizes the drying chamber, a circulation unit that circulates the steam in the drying chamber, and a steam superheating unit that superheats the steam in the drying chamber. A circulation path formed so that the steam superheated by the steam superheating means is circulated by the circulation means between the material to be dried and the steam superheating means, and the decompression means is controlled to control the drying chamber. And controlling the steam superheating means to control the superheated steam temperature at 30 ° C. or lower and the set temperature equal to or higher than the freezing temperature of the object to be dried by the steam superheating means. And a control means for performing the drying.

  In the first embodiment, first, the depressurizing means is operated to depressurize the drying chamber to the set pressure. The steam generated from the object to be dried or the steam used to exclude the air in the drying chamber is heated by the steam superheating means, and the temperature is increased to 30 ° C. or lower to a set temperature that is equal to or higher than the freezing temperature of the object to be dried. . The generated superheated steam is sent to the material to be dried by the circulation means through the circulation path. The surface of the object to be dried is heated by the superheated steam, and the moisture in the object to be dried moves to the surface and evaporates from the surface, whereby the drying proceeds.

During this drying process, the surface temperature of the material to be dried is maintained at a saturated vapor temperature corresponding to the set pressure. When the evaporation of moisture from the material to be dried is eliminated, the surface temperature rises higher than the saturated vapor temperature, but the set temperature is 30 ° C. or lower and is equal to or higher than the freezing temperature of the material to be dried. In addition to preventing heat denaturation of the product, it is possible to dry the material to be dried at a low temperature in a short time while suppressing the propagation of germs. When the drying process is completed, the return pressure means is operated to return the drying chamber to atmospheric pressure.

  Each component of the first embodiment will be described. The material to be dried is preferably a food, but is not limited thereto. The drying chamber may be of any type, type, and size as long as it forms a sealed space that accommodates an object to be dried and can take in and out the object to be dried. The drying chamber can be referred to as a drying chamber, a drying section, a drying container, and the like, and can be referred to as a pressure vessel because the inside is depressurized to an atmospheric pressure or lower.

  The decompression means has a function of decompressing the drying chamber to the set pressure that is equal to or lower than atmospheric pressure. This decompression means includes a decompression line and a decompressor, one end of which is connected to the drying chamber. In order to lower the saturated steam temperature in the drying chamber (set the set temperature to 30 ° C. or lower), the decompressor preferably has a steam ejector, a heat exchanger for condensation, and a water ring vacuum pump connected in series. However, the present invention is not limited to this.

  One end of the decompression line is preferably connected to the bottom of the drying chamber. With this configuration, it is possible to effectively eliminate air described later.

  The pressure reducing means preferably includes a pressure adjusting means that can continuously adjust the pressure change in the drying chamber. The pressure adjusting means can be a pressure adjusting valve such as a motor valve provided between the pressure reducing means and the drying chamber and capable of continuously changing the opening degree, and a vacuum pump capable of adjusting the number of rotations. It can also be.

  The steam superheater preferably has a function of heating the passing steam and generating superheated steam having a predetermined temperature with a predetermined degree of superheat. This steam superheater is preferably a finned heat exchanger. This steam superheater can be an electric heater or a heat exchanger that allows a predetermined high-temperature heat medium to flow inside. The heat medium is preferably oil or hot water, which can be controlled easily at a relatively low temperature, but can also be steam.

  The circulation means is preferably provided in the drying chamber together with the circulation path. The air in the drying chamber is circulated. Preferably, the fan is driven by a motor and forcibly circulates the air. The fan type is preferably an axial flow type, but may be a centrifugal type fan or the like.

  The fan is preferably connected to the motor by a rotating shaft that penetrates the drying chamber wall, and a sealing means that hermetically seals the rotating shaft portion is provided in the penetrating portion.

  The circulation path is preferably formed by a circulation path component in the drying chamber so that the steam superheated by the steam superheating means is circulated by the circulation means between the material to be dried and the steam superheating means. The And this circulation path | route structural member is preferably comprised by the partition wall etc. which partition the said drying chamber into the 1st area | region and the 2nd area | region up and down. An object to be dried can be accommodated in the first region, and the steam superheater and the circulation means can be disposed in the second region.

  The circulation path may be formed by forming a first opening and a second opening between the partition wall and the drying chamber wall, or forming the first opening and the second opening in the partition wall, The first region → the first opening → the second region → the second opening → the first region can be formed.

The said partition wall is comprised so that attachment or detachment is possible, and it is comprised so that the said steam superheater may be exposed from the opening which puts in / out the to-be-dried material of the said drying chamber in the removed state. With such a configuration, the steam superheater can be easily repaired and inspected.

  As the circulation path constituting member, the first air blowing guide for returning the steam after drying the object to be dried to the first opening of the partition wall and the steam from the second opening of the partition wall are guided toward the object to be dried. A second air guide that performs the operation can be provided in the second region. The first air guide and the second air guide are preferably configured to be detachable from the partition wall. The first air guide and the second air guide are preferably formed in a duct shape.

  A decompression means is connected to the drying chamber. The return pressure means has a function of returning the pressure in the drying chamber to the atmospheric pressure by communicating with the atmosphere after the drying process. The return pressure means includes a return pressure line connected to the drying chamber, and a filter and a return pressure valve provided in the return pressure line.

  The control means inputs a pressure sensor for detecting the pressure in the drying chamber and a signal from a temperature sensor for detecting the temperature in the drying chamber, and based on a drying program stored in advance, the pressure reducing means, the steam superheating means And the return pressure means and the like are controlled.

  The temperature sensor is preferably provided on the downstream side of the steam superheating means and on the upstream side of the material to be dried. With this configuration, the superheated steam temperature can be accurately controlled.

  The drying program controls the pressure reducing means to control the pressure in the drying chamber to a set pressure, and controls the steam superheating means to control the steam temperature superheated by the steam superheating means to 30 ° C. or less. A drying step performed by controlling to a set temperature that is equal to or higher than the freezing temperature of the dried product, and a re-pressure step for controlling the pressure-reducing means to return the pressure in the drying chamber to atmospheric pressure after the drying step.

This drying program is preferably provided with an air exclusion step for excluding air in the drying chamber before the drying step. Preferably, the air exhausting step is provided with a steam generating means, and the control means controls the steam generating means to generate steam, and also controls the pressure reducing means to depressurize the drying chamber. Configure to eliminate. The steam generating means is preferably provided outside the drying chamber, but can be provided inside the drying chamber.

  According to this air exclusion configuration, the air in the drying chamber can be excluded before the drying step. If this air exclusion is not performed, air remains in the drying chamber, which causes a heat transfer failure between the superheated steam and the object to be dried and inhibits drying, but this drying inhibition can be prevented.

  Moreover, by performing air exclusion by supplying steam, superheated steam can be produced by the steam superheating means using the steam filled in the drying chamber after the air is exhausted. Thereby, the to-be-dried object can be efficiently dried at the initial stage of the drying process. In the initial stage of the drying process, there is little steam generated from the material to be dried, and it is possible to eliminate the disadvantage that the amount of superheated steam necessary for drying cannot be immediately generated even if the steam heating means is operated.

  In the air evacuation, the steam supply is preferably performed after the pressure in the drying chamber is reduced to a predetermined pressure, but is not limited thereto.

  The present invention is not limited to the first embodiment, but includes the following second to fifth embodiments.

(Embodiment 2)
The second embodiment includes the heat retaining means for the inner wall temperature of the drying chamber in the first embodiment, and the control means controls the heat retaining means so that the inner wall temperature of the drying chamber is equal to or higher than the saturation temperature of the steam. The drying apparatus is characterized in that the drying process is performed while being held in a vacuum.

  According to the second embodiment, the superheated steam circulating through the circulation path is prevented from condensing in contact with the drying chamber wall. When the superheated steam is condensed, the drying efficiency is lowered. However, with the above heat retaining configuration, the drying with the superheated steam can be performed efficiently.

  In the second embodiment, as the heat retaining means, preferably, the drying chamber wall has a double-walled jacket structure, the outer periphery thereof is surrounded by a heat insulating material, and a predetermined temperature such as hot water or oil is introduced into the jacket. The controlled heat medium can be circulated and supplied. Further, the heat retaining means may be configured such that a heating means such as an electric heater formed in a pipe shape is attached to the outer periphery of the drying chamber wall and the outside is covered with a heat insulating material.

(Embodiment 3)
The third embodiment includes a valve capable of continuously adjusting the opening of the decompression unit in the first to second embodiments, and the control unit controls the valve to control the drying. The drying apparatus is characterized in that the indoor pressure is controlled to the set pressure.

  According to the third embodiment, the pressure fluctuation in the drying chamber can be reduced, and as a result, the fluctuation of the temperature of the object to be dried can be suppressed, so that the object to be dried with less heat denaturation can be produced.

(Embodiment 4)
The fourth embodiment is the same as in the first to third embodiments, the fan disposed in the drying chamber for circulating steam, the motor disposed outside the drying chamber for driving the fan, and the motor. An air-tight sealing means for hermetically blocking the drying room space is provided.

  In the fourth embodiment, the fan and the motor are connected by a rotating shaft that penetrates the chamber wall of the drying chamber, and the hermetic sealing means is configured to hermetically seal the rotating shaft portion.

  According to the fourth embodiment, the motor is not subjected to pressure fluctuation and a reduced pressure environment, so that the motor for driving the fan can be easily selected and contamination of the object to be dried can be prevented.

(Embodiment 5)
In the fifth embodiment, in the first to fourth embodiments, in addition to drying the object to be dried by the drying step, the control unit vacuum-cools the object to be processed by operating the pressure reducing unit. It is the drying apparatus characterized by performing so.

  According to the fifth embodiment, in addition to the drying function, a vacuum cooling function can be added, and the function of the drying device can be expanded.

  Hereinafter, a specific embodiment 1 of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of the drying apparatus 1 of the first embodiment, FIG. 2 is a diagram for explaining an outline of the drying program of the first embodiment, and FIG. 3 is a main part of the first embodiment. It is explanatory drawing of a cross section.

<Configuration of Example 1>
The drying apparatus 1 according to the first embodiment includes a drying chamber 3 that accommodates an object to be dried 2, a decompression unit 4 that depressurizes the interior of the drying chamber 3, and a vapor provided in the drying chamber 3. The fan 5 as a circulating means for circulating the steam, the steam superheater 6 as the steam superheating means for superheating the steam in the drying chamber 3, and the steam superheated by the steam superheater 6 are to be dried 2 and the steam. The circulation path 7 formed in the drying chamber 3 so as to circulate with the superheater 6 by the fan 5 and the pressure reducing means 4 are controlled to set the pressure P in the drying chamber 3 to the set pressure P1. A controller 8 that controls the steam superheater 6 to control the steam temperature T superheated by the steam superheater 6 to a set temperature T1 and performs a drying process is provided as a main part.

  Each component of the first embodiment will be described below. The to-be-dried object 2 is made into the raw fish and meat used as the drying object weak to heat metamorphosis. The drying chamber 3 forms a sealed space for accommodating the object to be dried 2 and is provided with an openable / closable door (not shown) for taking the object to be dried 2 in and out, and the pressure inside the pressure chamber is reduced to an atmospheric pressure or lower. It is configured as.

  The drying chamber 3 has an inner wall whose temperature is equal to or higher than the saturated steam temperature corresponding to the saturated steam pressure P1 in the drying chamber 3 (preventing condensation of superheated steam), and the superheated steam temperature generated by the steam superheater 6. In order to keep the temperature at a predetermined temperature equal to or lower than (the set temperature T1), the wall surface is configured as a jacket 9 having a double wall structure. The outer periphery of the jacket 9 is surrounded by a heat insulating material (not shown).

  In order to circulate and supply hot water of a predetermined temperature into the jacket 9 and keep the inner wall temperature of the drying chamber 3 at a set temperature T2 which is not less than a saturated steam temperature and not more than the set temperature T1, a hot water generator 10 and a circulation A circulation line 12 having a pump 11 is provided. A circulation path (not shown) is formed in the jacket 9 by appropriate partitions. The jacket 9, the hot water generator 10, the circulation pump 11 and the circulation line 12 constitute a heat retaining means.

  Further, a steam generator 13 for supplying steam into the drying chamber 3 is provided, and the steam generator 13 and the inside of the drying chamber 3 are connected by a steam supply line 14. Is provided with a steam valve 15 for controlling the supply of steam into the drying chamber 3.

  The drying chamber 3 is partitioned by a partition wall 16 into an upper first region 17 and a lower second region 18. In the first area 17, the material to be dried 2 is accommodated, and in the second area 18, the fan 5 and the steam superheater 6 are arranged.

  The decompression means 4 has a function of decompressing the interior of the drying chamber 3 to the set pressure P1 that is equal to or lower than the atmospheric pressure, and a decompressor provided at one end of the decompression line 19 connected to the drying chamber 3 and the decompression line 19 20. In the first embodiment, the decompressor 20 is a combination of a steam ejector, a heat exchanger for steam condensation, and a water ring vacuum pump (all not shown). One end of the decompression line 19 is connected to the bottom of the drying chamber 3.

  Further, the pressure reducing means 4 is provided with a pressure adjusting valve 23 that can continuously adjust the pressure change in the drying chamber 3. In the first embodiment, the pressure regulating valve 23 uses a motor valve.

The steam superheater 6 has a function of heating the steam that is circulated and passed by the fan 5 and generating superheated steam at the set temperature T1 with a predetermined superheat degree K. The steam superheater 6 is a heat exchanger with fins (both not shown) and fins attached to the pipe containing the electric heater and the pipe. The steam superheater 6 is energized by the switch 2 provided in the power supply line 21.
2 to perform the opening / closing control.

  The fan 5 circulates the superheated steam in the drying chamber 3 and is driven by a motor 24. The motor 24 is disposed outside the drying chamber 3 and is connected to the motor 24. This connecting portion is provided with a sealing means 50 shown in FIG. The sealing means 50 prevents the outside air from entering the drying chamber 3 under reduced pressure through the through-hole through which the rotary shaft 52 of the fan 5 passes, and the lubricating oil of the motor 24 is contained in the drying chamber 3. It has a function to prevent intrusion.

  The circulation path 7 is formed by a circulation path component in the drying chamber 3 so that the steam superheated by the steam superheater 6 is circulated by the fan 5 between the material to be dried 2 and the steam superheater 6. It is formed. The circulation path component includes the partition wall 16 and the inner wall of the drying chamber 3.

  The circulation path 7 is formed by forming a first opening 27 and a second opening 28 between the partition wall 16 and the inner wall of the drying chamber 3, so that the first region 17 → the first opening 27 → the second The path is formed as a region 18 → the second opening 28 → the first region 17.

  The partition wall 16 is configured to be detachable, and is configured such that the steam superheater 6 is exposed from an opening through which the material to be dried 2 in and out of the drying chamber 3 is taken in and out. With such a configuration, the steam superheater 6 can be easily cleaned and inspected.

  In the first embodiment, as the circulation path constituting member, a cylindrical fan guide 29 and a first shielding member 30 that shields between the fan guide 29 and the partition wall 16 and the bottom wall of the drying chamber 3. A second shielding member 31 that shields between the steam superheater 6 and the partition wall 16 and the inner wall of the drying chamber 3; and a steam that has dried the object to be dried 2 is returned to the first opening 27. One blowing guide 32 and a second blowing guide 33 that guides the steam from the second opening 28 toward the object to be dried 2 are provided in the second region 18. The first air guide 33 and the second air guide 33 are configured to be detachable from the partition wall 16.

  A decompression means 34 is connected to the drying chamber 3. The return pressure means 34 has a function of returning the pressure to the atmospheric pressure by communicating the inside of the drying chamber 3 with the atmosphere after completion of the drying process. The return pressure unit 34 includes a return pressure line 35 connected to the drying chamber 3, an air cleaning filter 36 and a return pressure valve 37 provided in the return pressure line 35.

  The controller 8 inputs signals from a pressure sensor 38 for detecting the pressure in the drying chamber 3 and a temperature sensor 39 for detecting the temperature in the drying chamber 3, and based on the drying program stored in advance, The hot water generator 10, the circulation pump 11, the steam generator 13, the steam valve 15, the decompression means 4, the switch 22, the return pressure means 34, and the like are controlled.

  The temperature sensor 39 and the pressure sensor 38 are provided between the steam superheater 6 and the material to be dried 2 on the downstream side of the steam superheater 6.

The drying program controls the pressure reducing means 4 to control the pressure P in the drying chamber 3 to a set pressure P1, and also controls the steam superheater 6 to superheat the steam temperature heated by the steam superheater 6. A drying step in which T is controlled to a set temperature T1, and a return pressure step in which the return pressure means 34 is controlled to return the pressure in the drying chamber 3 to atmospheric pressure after the drying step. In Example 1, when the set temperature T1 is set to 30 ° C., the pressure P in the drying chamber 3 is controlled by the saturated vapor pressure P1 corresponding to the freezing temperature to 20 ° C., and the drying temperature (the material to be dried at the time of evaporative drying) (Surface temperature of 2) is in the range of the freezing temperature to 20 ° C., and drying is performed. Further, the set temperature T1 is 20 ° C.
In this case, the inside pressure P of the drying chamber 3 is controlled by a saturated vapor pressure P1 corresponding to a freezing temperature of 10 ° C., and drying is performed with the drying temperature in the range of the freezing temperature of 10 ° C.

  This drying program is provided with an air exclusion process for excluding air in the drying chamber 3 before the drying process. This air evacuation step is configured to supply steam from the steam generator 10 into the drying chamber 3 and to control the decompression means 4 to decompress the interior of the drying chamber 3.

  The steam circulation flow rate by the fan 5 during the drying process is controlled to about 10 to 30 m / s in order to maintain a predetermined drying speed.

  In addition, the inner wall temperature of the drying chamber 3 is kept at the set temperature T2 by circulating and supplying hot water to the jacket 9 during the drying step.

  Here, the configuration of the hermetic sealing means 50 will be described with reference to FIG. The secret seal means 50 positions the first bearing 56 and the second bearing 57 that support the rotary shaft 52 at the left and right ends thereof, and positions the first bearing 56 and the second bearing 57. And a fixing cylinder 58 for fixing the motor 24 and a sealing member 59 for hermetically sealing the end of the fixing cylinder 58 on the drying chamber 3 side.

  The first bearing 56 and the second bearing 57 are positioned and fixed in a first through hole 60 formed in the fixed cylinder 58. The first bearing 56 and the second bearing 57 function to smooth the rotational motion of the rotary shaft 52, maintain the rotational accuracy, and simultaneously support the load in the gravity direction.

  The fixed cylinder 58 passes through a second through hole 61 formed in the chamber wall 51 and is fixed. The fixing cylinder 58 is fixed to the chamber wall 51 and fixed to the motor 24 using a first flange 62 and a second flange 63 provided integrally with the fixing cylinder 58, respectively. The inner diameter of the second through-hole 61 is formed slightly larger than the outer diameter of the fixed cylinder 58 to facilitate the insertion of the fixed cylinder 58.

  That is, the first flange 62 is joined to a third flange 64 formed on the chamber wall 51 via an annular flange packing 70 and fixed by bolts and nuts (not shown), respectively. The cylinder 58 is detachably fixed to the chamber wall 51. The hermetic seal between the fixed cylinder 58 and the second through hole 61 is realized by the first flange 62, the flange packing 70 and the third flange 64, and the first flange 62, the flange The packing 70 and the third flange 64 constitute an airtight sealing means.

  In addition, the second flange 63 is joined to a fourth flange 65 formed as a part of the case of the motor 24, and is fixed by bolts and nuts (not shown), so that the fixed cylinder 58 is Removably fixed to the chamber wall 51. The fixed cylinder 58 is formed of SUS, but is not limited thereto.

  The seal member 59 is a member for hermetically sealing (sealing) a gap formed between the rotary shaft 52 and the first through hole 60 of the fixed cylinder 58. The seal member 59 includes a sealing plate 66, a first annular packing 67, a second annular packing 68, and a pressing plate 69.

The sealing plate 66 has a third through hole 71 through which the rotating shaft 52 passes, and the fixed cylinder 58 is sealed so as to seal an end of the first through hole 60 facing the drying chamber 3. It is attached to a recess 72 formed at the end of the.

  The first annular packing 67 is attached to the constituent surface of the third through hole 71 so as to seal between the third through hole 71 of the sealing plate 66 and the rotary shaft 52. The first annular packing 67 is a rotary seal that seals the rotary shaft 52 rotatably. The second annular packing 68 is attached to the outer peripheral surface of the sealing plate 66 so as to seal between the outer peripheral surface of the sealing plate 66 and the recess 72. The second annular packing 68 is composed of an O-ring made of silicon rubber.

  The presser plate 69 is detachably fixed to the end surface of the fixed cylinder 58 facing the drying chamber 3 by a screw 73 so that the sealing plate 66 is pressed and fixed to the recess 72.

  The fixed cylinder 58 is formed with an operation hole 74 for allowing the shaft coupling 54 and the rotary shaft 52 to be connected or disconnected from the outside of the fixed cylinder 58.

  In the above configuration, various methods are conceivable for fixing the motor 24 and the fan 5 to the chamber wall 51, but they can be fixed by the following method. First, outside the drying chamber 3, the rotary shaft 52 and the motor shaft 53 are connected by the shaft coupling 54. Then, the connected rotary shaft 52 is inserted into the first through hole 60 of the fixed cylinder 58 on which the first bearing 56 and the second bearing 57 are mounted. In this state, the sealing plate 66 to which the first annular packing 67 and the second annular packing 68 are attached is attached to the recess 72 and fixed to the fixed cylinder 58 by the presser plate 69.

  Then, by fixing the second flange 63 and the fourth flange 65, the fixed cylinder 58 and the motor 24 are integrated. Next, the fixed cylinder 58 is inserted into the second through hole 61, and the first flange 62 and the third flange 64 are fixed with the flange packing 70 interposed therebetween. Finally, the fan 5 and the rotating shaft 52 are connected by the fan boss 55. Thus, the motor 24 can be fixed to the drying chamber 3 in a state where the rotary shaft 52 is hermetically sealed by the first annular packing 67 and the second annular packing 68 attached to the sealing plate 66. it can.

<Operation of Example 1>
The operation of the first embodiment will be described below with reference to FIGS. 1 and 2. Now, the set pressure P1 is set to a saturated steam pressure of 10 ° C., the set temperature T1 is set to 30 ° C., and the superheat degree (superheated steam temperature−saturated steam temperature) K is set to 20 ° C. And if the to-be-dried object 2 is accommodated in the said drying chamber 3, and the operation start switch (illustration omitted) is operated, air exclusion process S1 of FIG. 2 will be started.

(Air exclusion process)
This air exclusion process S1 is performed as follows. First, the return pressure valve 37 is closed, the pressure adjustment valve 23 is controlled, and the pressure reducer 20 is operated. Next, the steam generator 10 is operated (it is preferable to operate before the air exhausting step), the second valve 15 is opened, and the steam is supplied into the drying chamber 3. Then, since the specific gravity of the air in the drying chamber 3 is larger than that of the steam, the air is discharged to the outside of the drying chamber 3 through the decompression line 19 while being pushed downward by the steam. If an air exclusion process is performed only for the predetermined time, it will transfer to the following drying process S2. At the time of transition to the drying process, the pressure in the drying chamber 3 is reduced to the set pressure P1.

(Drying process)
This drying step S2 is performed as follows. The steam superheater 6 is activated (preferably, activated before entering the drying step S2), and the circulation pump 11 is driven to circulate and supply hot water into the jacket 9, and the drying chamber 3. The temperature of the inner wall is kept at the set temperature T2.

  Then, while driving the motor 24, the pressure reducing means 4 and the steam superheat so that the pressure detected by the pressure sensor 38 becomes the set pressure P1 and the temperature detected by the temperature sensor 39 becomes the set temperature T1. The device 6 is controlled.

  Thereby, the circulation flow of the superheated steam in the circulation path 7 in the drying chamber 3 is the fan 5 → the steam superheater 6 → the second opening 28 → the second air blowing guide 33 → the object to be dried 2 → the above. The first blower guide 32 → the first opening 27 → the fan 5 is formed as indicated by a broken arrow.

  In the circulating flow, the pressure of the circulating superheated steam is controlled to the set pressure P1 by the action of the pressure regulating valve 23. The steam after passing through the steam superheater 6 is converted to superheated steam having the set temperature T1 obtained by adding the degree of superheat K to the saturated steam temperature corresponding to the set pressure P1, and is sent to the object to be dried 2. That is, the material to be dried 2 is dried by the superheated steam at the set temperature T1 at the set pressure P1.

  The surface of the object to be dried 2 is heated by the superheated steam, and the moisture in the object to be dried 2 moves to the surface and evaporates from the surface, whereby the drying proceeds. This drying step is performed for a preset drying time. During the drying step S2, the surface temperature of the material to be dried 2 is maintained at a saturated vapor temperature corresponding to the set pressure P1.

  When the evaporation of moisture from the material to be dried 2 is eliminated, the surface temperature rises above the saturated vapor temperature. However, since the temperature of the superheated steam is set to about 30 ° C. or lower, thermal denaturation of the material to be dried 2 is suppressed as compared with the superheated steam temperature of 50 ° C. or higher. Moreover, since it is set as the superheated steam of the optimal growth temperature of 55 degreeC or less of a high temperature microbe, the growth of a high temperature microbe is suppressed in a drying process. If the superheated steam temperature is set to 25 or less of the minimum growth temperature of mesophilic bacteria, the growth of mesophilic bacteria can also be suppressed.

(Return pressure process)
When the drying step S2 is completed, a pressure-reducing step S3 is performed. In this pressure recovery step S3, the steam valve 15, the pressure regulating valve 23, and the switch 22 are closed, the operations of the circulation pump 11, the motor 24, and the steam superheater 6 are stopped, and the pressure recovery means 34 is recovered. Is performed. The operation of the return pressure means 34 is performed by opening the return pressure valve 37. Thereby, outside air is introduced into the drying chamber 3 through the return pressure line 35, and the inside of the drying chamber 3 returns to atmospheric pressure. When the atmospheric pressure is detected by the pressure sensor 38, the return pressure step S3 is terminated.

  When this decompression step S3 is completed, the object to be dried 2 is taken out of the drying chamber 3 and the drying operation is terminated. The drying operation is ended by operating an operation end switch (not shown).

  The operational effects of the first embodiment are as follows. First, since the fan 5 and the circulation path 7 are provided in the drying chamber 3, the air leakage is less and the drying speed is faster than that in which the circulation path is formed outside. Further, since the heat loss in the circulation path 7 is small and only the evaporated water is discarded, a drying device with high drying efficiency can be provided. Further, it is possible to easily prevent condensation of superheated steam in the circulation path 7.

Moreover, since it is made to dry the to-be-dried material 2 with the low-temperature superheated steam of 30 degrees C or less, while being able to suppress the thermal denaturation of the to-be-dried material 2 by a high-temperature superheated steam, it suppresses the proliferation of miscellaneous bacteria. be able to. Furthermore, since the drying can be performed in an oxygen-free state, deterioration due to oxidation of the object to be dried 2 can be minimized.

  In addition, drying with dehumidified air has a low drying rate at 30 ° C. or lower, particularly 10 ° C. or lower, but drying can be performed at a lower temperature and higher speed than drying with dehumidified air.

  Further, since the air exclusion step S1 is performed before the drying step S2, the air remains in the drying chamber 3, and the efficiency of drying is reduced due to the heat transfer failure between the superheated steam and the material 2 to be dried. Can be prevented.

  Further, by performing air exclusion by supplying steam, the steam superheater 6 can be used as the superheated steam by using the steam filled in the drying chamber 3 after the air is exhausted. Can be efficiently dried.

  Furthermore, during the drying step S2, the inner wall temperature of the drying chamber 3 is maintained at the set temperature T2 (saturated steam temperature and lower than the previous set temperature T1), so that superheated steam comes into contact with the inner wall, It does not condense and does not radiate heat to the atmosphere through the inner wall. For this reason, the drying efficiency is high.

  The present invention is not limited to the first embodiment. In the first embodiment, the temperature of the superheated steam used for drying is set to 30 ° C. or lower. However, the apparatus can perform a reduced pressure drying with superheated steam of 50 ° C. or higher. The configuration of the circulation path 7 can be variously changed.

It is explanatory drawing explaining schematic structure of Example 1 of this invention. It is a flowchart figure explaining the drying program of the Example 1. FIG. It is explanatory drawing of the principal part expanded cross section of the Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Drying device 2 To-be-dried object 3 Drying chamber 4 Pressure reduction means 5 Fan (circulation means)
7 Circulation path 8 Controller (control means)

Claims (4)

A drying chamber for storing the objects to be dried;
Decompression means for decompressing the drying chamber;
A circulating means for circulating the steam in the drying chamber;
Steam superheating means for superheating steam in the drying chamber;
A circulation path formed so that the steam superheated by the steam superheating means is circulated by the circulation means between the material to be dried and the steam superheating means;
The pressure reducing means is controlled to control the pressure in the drying chamber to a set pressure, and the steam superheating means is controlled so that the superheated steam temperature is 30 ° C. or less, and the freezing temperature of the material to be dried And a control means for performing the drying process by controlling to the set temperature. A heat retaining means for the inner wall temperature of the drying chamber;
The drying apparatus according to claim 1, wherein the control unit controls the heat retaining unit to perform a drying step while maintaining an inner wall temperature of the drying chamber at or above a saturation temperature of steam.   The drying apparatus according to claim 1, wherein the circulation unit and the circulation path are provided in the drying chamber.   A steam generating means, wherein the control means operates the steam generating means and the pressure reducing means to exclude air in the drying chamber by the steam generated by the steam generating means before the drying step. The drying apparatus according to any one of claims 1 to 3.