JP2007085600A - Decompression low temperature drying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently adjusting moisture of agricultural products, their residue or marine foods sufficiently to the inside in a short time without discoloration, deformation and deterioration. <P>SOLUTION: The rind of an apple 9 is placed on a horizontal shelf 4 received in a dry warehouse 1, and uniformly heated at about 60°C by a heat pipe 5 heated by hot water from a boiler 6. The air in the dry warehouse 1 is decompressed to about 150 mmHg by a vacuum pump, and further continuously dehumidified by being circulated in a condenser 32 or the like to promote drying. As the dehumidified heated air flows back to the dry warehouse 1, heat loss is reduced and energy can be substantially saved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a reduced-pressure low-temperature drying apparatus that can efficiently adjust or dry moisture of agricultural products, their residues and marine products in a short time while preserving color tone, shape, nutrition, minerals and fragrance.

  Conventionally, in the moisture adjustment and drying of agricultural products such as fruits and vegetables, or seafood such as seafood and seaweeds, they are heated to a relatively high temperature for the purpose of shortening the drying time and sufficiently drying the interior. In many cases, dehydration and drying are performed. However, when heated at a high temperature, depending on the object to be dried, the color tone, shape, fragrance, nutrients, minerals, etc. specific to the object to be dried may be damaged, burned, or uneven in drying.

  Fruits and vegetables such as apples, mandarin oranges, grapes, or tomatoes are often used after being processed into juice or confectionery materials. A residue appears. This residue contains a large amount of moisture, and in order to be reused, it is necessary to sufficiently dry and dehydrate, for example, to form a dry powder. Thus, for example, means for drying and dewatering by blowing hot air while stirring with a rotating drum or the like has been attempted.

  However, since these fruit and vegetable residues contain a large amount of sugar in addition to moisture, there is a problem that they become trapped during drying and stick to a rotating drum or the like, making stirring difficult. . Further, in order to sufficiently dry the inside of the residue, it is necessary to heat at a certain high temperature. However, when heated at a high temperature, there is a problem that discoloration or scorching occurs and the utility value as an edible material is lost. For this reason, most of the residues of fruits and vegetables have been processed into livestock feed or compost where discoloration is not a problem, or discarded.

  However, the residue of fruits and vegetables contains a large amount of plant fibers and polyphenols in addition to the three major nutrients of protein, lipids, and sugars. As an edible material, it has high utility value. Therefore, an efficient drying means is desired that does not stick to equipment during drying and dehydration, can be sufficiently dried to the inside, and does not discolor.

  Therefore, conventionally, a drying means for drying seafood and agricultural products themselves at a relatively low heating temperature and uniformly has been proposed using a heat pipe (see, for example, Patent Document 1). That is, this Patent Document 1 discloses a means for drying and dewatering by loading marine products such as cherry shrimp and scallops or agricultural products such as garlic on a belt conveyor surrounded by a heat insulating panel, and heating from above with a heat pipe. Has been.

This heat pipe is a well-known technique, and is filled with a refrigerant to an extent that occupies a percentage of the pipe volume and sealed, and this refrigerant is heated and vaporized by a heating means to generate refrigerant vapor. Is heat-condensed on the inner peripheral surface of the pipe to heat the peripheral wall of the pipe, and waves are further radiated by rapid heat transfer on the inner surface of the pipe. Therefore, when the heat pipe is installed horizontally, the refrigerant vapor spreads quickly over the entire length of the pipe and can be heated almost uniformly over the entire length of the heat pipe.
JP 2004-15688 A (pages 6-7, FIGS. 4-5)

  However, the drying means described above has the following problems to be improved. In other words, the agricultural products, their residues, or marine products containing a large amount of water, for example, around 80% by weight, are heated without increasing the temperature so as not to discolor, deform, or change to the inside. In order to sufficiently dry, for example, to around 10% by weight, a very long drying time is required, and the drying processing time and the energy cost required for heating increase, and the practicality is greatly reduced. Therefore, in order to enhance the practicality, it is a reciprocal condition that the temperature is not increased, preferably 60 ° C. or less, while the inside is sufficiently and uniformly dried, while the drying time is shortened and the heating energy cost is reduced. It is indispensable to satisfy the conditions.

  Accordingly, an object of the present invention is to efficiently dry or adjust the moisture of a material to be dried in a short time while preserving the color tone, shape, nutrition, mineral and scent of the material to be dried having various nutrients, fragrances and colors. It is an object of the present invention to provide a highly practical low-pressure low-temperature drying apparatus that can perform the above-described process.

  The inventor of the present application satisfies all of the following requirements, and the dried matter having various nutrients, fragrances, colors, etc., which is the above-mentioned problem, while maintaining the color tone, shape, nutrition, minerals, fragrance, etc. It has been found that moisture adjustment or drying can be carried out sufficiently and efficiently in a short time. That is, firstly, by placing a material to be dried on a horizontal shelf, a large amount of material to be dried is laid on a thin and wide area so that heat can easily pass through in a stationary state. Secondly, by providing a heat pipe below the horizontal shelf, a large amount of material to be dried laid in a large area is uniformly heated at a temperature that is not so high, preferably 60 ° C. or less.

  Thirdly, by storing the horizontal shelf in a drying cabinet and reducing the pressure inside the drying cabinet, the drying time at a low temperature is shortened. Fourthly, by separating the air and moisture in the drying chamber, water vapor generated by moisture adjustment or drying of the material to be dried is removed, and drying is promoted by suppressing an increase in humidity in the drying chamber. This further reduces the drying time. Fifth, the consumption heat energy is greatly reduced by recirculating the air from which water has been separated and removed into the drying chamber.

  That is, the reduced-pressure low-temperature drying apparatus according to the present invention is characterized by including a drying cabinet, a decompression unit that decompresses the inside of the drying cabinet, and a gas-liquid separation unit that separates moisture in the air in the drying cabinet. The drying cabinet stores a horizontal shelf on which an object to be dried is placed, and a heat pipe is provided below the horizontal shelf. The heat pipe includes a pipe in which a refrigerant is sealed and a heating unit that heats the refrigerant. The refrigerant is vaporized by the heating means, and the vaporized refrigerant dissipates heat to the inner peripheral surface of the pipe and condenses.

  The dried material is desirably either an agricultural product or a marine product. Furthermore, it is more desirable that the material to be dried is a residue of either fruit or vegetable. The heating means preferably includes a heating pipe penetrating the pipe in the axial direction and a heating source, and the heating pipe is desirably configured so that the liquid heated by the heating source circulates.

  Here, the “dryer” may be any size, shape, and material as long as it stores a “horizontal shelf” and a “heat pipe”, which will be described later, and can be sealed at the time of decompression or dehumidification. “Depressurizing means” means all means for reducing the atmospheric pressure in the drying chamber, and corresponds to, for example, a vacuum pump. “Gas-liquid separation means” means all means for separating the moisture in the air in the drying cabinet. For example, a means for absorbing moisture contained in the dehumidifier, or letting the air in the drying cabinet touch the low-temperature equipment. A means for condensing and removing the contained water is applicable.

  “Dried material” means an object to be moisture-adjusted or dried, and includes, for example, agricultural products such as fruits and vegetables, squeezed residues thereof, and marine products such as fish shellfish and seaweed. The “horizontal shelf” means a substantially horizontal shelf on which an “object to be dried” can be placed, and its size, shape, and material are not limited. Moreover, it is not limited to a single stage, and includes a case of a plurality of stages separated by a predetermined height direction interval. The “heat pipe” is a known technique as described above, in which a refrigerant is filled and sealed to an extent that occupies some percent of the pipe volume. Is generated, and the refrigerant vapor is radiated and condensed on the inner peripheral surface of the pipe to heat the peripheral wall of the pipe.

  In addition, “refrigerant” means a medium that changes phase from a liquid to a gas at a temperature that is not so high, for example, 100 ° C. or less, and includes, for example, ethanol, methanol, water, and the like. Also, here, “the heat pipe is provided under the horizontal shelf” means that the “heat pipe” is arranged along the horizontal shelf at a predetermined interval from the lower side of the horizontal shelf. The arrangement structure of the “heat pipe” is not limited as long as the fruit residue placed on the horizontal shelf can be heated almost uniformly.

  The “heating means” includes all means capable of heating the refrigerant sealed in the pipe. For example, a heating pipe having a smaller diameter is passed through the pipe in the axial direction, and the heating liquid is supplied into the heating pipe. Circulates and the one that inserts a heating element into the pipe and supplies electricity to the heating element. The “fruit or vegetable residue” means a large amount of skin, core, squeezed rice cake, etc. that are produced when processing fruits such as apples, tangerines or grapes, or vegetables such as tomatoes. “Heat source” means any means capable of heating the liquid circulating through the heating pipe described above, for example, combustion heat of solid fuel, liquid fuel or gaseous fuel, heat from an electric heater, or from other equipment. Exhaust heat is applicable. “Liquid” means a liquid fluid that circulates in the heating pipe described above, and corresponds to, for example, hot water or oil.

  A large amount of agricultural products, these residues, or agricultural products can be efficiently dried and dehydrated in a short time without causing discoloration, deformation, or alteration. In other words, it is indispensable to dry for a long time without raising the temperature in order to sufficiently dry these objects containing a large amount of moisture without causing discoloration, deformation, or alteration, and to the inside. However, on the other hand, in order to improve productivity and suppress an increase in the cost of the drying process, it is possible to satisfy the conflicting condition that the drying time must be shortened, so that high practicality can be exhibited. . Further, it is possible to prevent scorching or sticking to a drying apparatus, tray, or the like during drying of a fruit or vegetable residue containing a large amount of sugar.

  As a heating means for the refrigerant sealed in the heat pipe, the temperature of the heat pipe is maintained even if the heat pipe becomes long by circulating the liquid heated by the heating source through the heating pipe that penetrates the pipe in the axial direction. Uniformity is facilitated, energy consumption in the heating source can be reduced, and a heating means that can easily adjust the temperature can be manufactured at low cost.

  The configuration of the reduced-pressure low-temperature drying apparatus according to the present invention will be described with reference to FIGS. That is, as shown in FIG. 1, the reduced-pressure low-temperature drying apparatus according to the present invention includes a box-type drying cabinet 1, a decompression means 2 provided above the drying cabinet, and a gas-liquid separation means provided on the right side of the drying cabinet. 3 is provided. The drying cabinet 1 stores a total of twelve horizontal shelves 4 that are composed of two rows and six columns when viewed from the front, and heat pipes 5 are arranged below the horizontal shelves. It is. These structures will be described in detail below.

  The drying cabinet 1 is a sealed container made of a heat insulating panel having a height of about 160 cm, a width of about 330 cm, and a depth of about 120 cm. The front wall in FIG. 1 opens both sides so that the horizontal shelf 4 can be taken in and out. A sealable door (not shown) is attached. The decompression means 2 includes a first duct 21 communicating with the ceiling of the drying chamber 1, a suction duct 22 communicating with the left side of the upper end of the first duct, and a vacuum pump 23 communicating near the left end of the suction duct. ing. The suction duct 22 is provided with an electromagnetic valve 24 at a position upstream of the vacuum pump 23.

  The gas-liquid separation means 3 collects the second duct 31 communicating with the right side of the upper end of the first duct 21, the condenser 32 provided at the other end of the second duct, and the water separated by the condenser. A condensate recovery unit 33 and a third duct 34 for returning the air from which moisture has been separated from the condensate recovery unit to the drying chamber 1 are provided. The second duct 31 is provided with a blower fan 35 for circulating the air in the drying cabinet 1.

  The condenser 32 includes a sealed condensation container 321, a cooling pipe 322 communicating from the right side in the condensation container, and a refrigeration unit 323 that circulates cold water through the cold water pipe. The bottom of the condensing container 321 communicates with the condensate recovery unit 33 via a duct, and the third duct 34 that returns the above-described dehumidified air to the drying chamber 1 communicates with the upper left side of the condensate recovery unit. Yes. A drain valve 332 is provided at the bottom of the condensate recovery unit 33 for discharging the separated water accumulated in the condensate recovery unit in a timely manner. A level sensor 331 for measuring the amount of separated water accumulated in the condensate recovery unit is attached to the right side of the condensate recovery unit 33.

  The horizontal shelf 4 housed in the drying cabinet 1 is a shallow tray made of synthetic resin, and is supported by guide rails (not shown) provided in the drying cabinet. It can be put in and out. The horizontal shelf 4 is desirably provided with a large number of fine holes, slits, and the like in order to improve air circulation.

  As shown in FIGS. 1 and 2, the heat pipes 5 are arranged in seven rows in the depth direction on the lower side of the horizontal shelf 4 over the entire length of the horizontal shelf in the left-right direction. As will be described later, the heat pipe 5 includes a pipe 51 in which a refrigerant is sealed, and a heating pipe 52 that penetrates the pipe in the longitudinal direction. And the pipe 51 which sealed the refrigerant | coolant is provided under each horizontal shelf 4, The heating pipe 52 has connected all these pipes in series. If the vertical part of the heating pipe is connected by a flexible tube such as a rubber hose, the movement and adjustment in the height direction can be facilitated.

  The inlet part A and the outlet part B located at both ends of the heating pipe 52 are a boiler 6 installed on the left side of the drying chamber 1, and a hot water supply pipe 53 and a waste hot water each wound with a heat insulating material (not shown). A pipe 54 is connected through the side wall of the drying cabinet. Then, the hot water heated by the boiler 6 flows into the inlet A of the heating pipe 52 through the hot water supply pipe 53, and the hot water that has flowed in passes through all the pipes 51 connected in series. From the outlet B, the boiler is recirculated through the hot water pipe 54.

  A pressure gauge 7 and a thermometer 8 are installed on the ceiling of the drying chamber 1 to measure the pressure and temperature in the drying chamber.

  Next, the configuration and operation of the heat pipe 5 will be described with reference to FIGS. 3 and 4. As shown in FIG. 3, the heat pipe 5 includes a pipe 51 having a diameter of about 5 cm each made of a stainless steel pipe, and a heating pipe 52 having a diameter of about 1 cm that penetrates the pipe in the axial direction. As shown in the cross section of the heat pipe 5 in FIG. 4, the pipe 51 contains an amount of refrigerant, for example, ethanol 55, in which the heating pipe 52 is almost buried. Note that the hot water 56 heated by the boiler circulates in the heating pipe 52 as described above.

  When the hot water 56 warmed by the boiler is supplied to the heating pipe 52, the temperature of the heating pipe rises, and the ethanol 55 surrounding the outside is warmed and vaporized. The vapor of the vaporized ethanol 55 touches the inner periphery of the low temperature pipe 51 to dissipate heat, warms the pipe, condenses it into liquid ethanol, and drops it. The vaporized ethanol 55 vapor is quickly mixed and diffused over the entire length of the pipe 51, so that the pipe can be warmed at a substantially uniform temperature.

  Next, the use of the reduced-pressure low-temperature drying apparatus according to the present invention will be described. First, on the horizontal shelf 4 shown in FIG. 1, as an object to be dried, for example, apple skin 9 which is a fruit residue is mounted in a thickness of about 150 kg and several centimeters and stored in the drying cabinet 1. Next, the door of the drying cabinet 1 is sealed, the boiler 6 is ignited, and the blower fan 35 and the vacuum pump 23 are driven. The temperature in the drying chamber 1 is set to about 60 ° C. and the pressure is set to 100 to 150 mmHg. In order to warm the drying chamber to this temperature, the hot water supply temperature from the boiler 6 is 70 ° C., and the hot water supply amount is 3.3 liters. Set to about / min. Note that the temperature and pressure in the drying chamber 1 are measured by the thermometer 8 and the pressure gauge 7, and the rotation speed of the vacuum pump 23 and the fuel to the boiler 6 are maintained so as to maintain the above-described temperature and pressure. The supply amount is automatically controlled.

  The apple skin 9 placed on the horizontal shelf 4 is heated to around 60 ° C. by the heat pipe 5 provided on the lower side thereof, and moisture is gradually evaporated and dehydrated. The humid air in the drying cabinet 1 is sent to the condenser 32 by the blower fan 35 via the first duct 21 and the second duct 31 communicating with the ceiling of the drying cabinet 1. The moist air sent to the condenser 32 comes into contact with the cooling pipe 322 in the condensing container 321 constituting the condenser, the contained water is condensed, and the liquid is separated into air and water.

  The separated water condensed in the condenser 32 falls downward and accumulates at the bottom of the condensed water recovery device 33, while the air from which the water has been separated passes through the third duct 34 communicating with the upper portion of the condensed water recovery device. Return to the drying chamber 1. The amount of separated water collected at the bottom of the condensate recovery unit 33 is measured by the level sensor 331, and when it reaches a predetermined amount, the drain valve 332 is opened and discharged. In addition, about 3 hours is sufficient for the drying time in this embodiment.

  As described above, the apple skin 9 mounted on the horizontal shelf 4 is uniformly heated to 60 ° C., which is not so high, by the heat pipe 5, so it does not change color and is contained by a large amount of sugar. It is dried and dehydrated without any wrinkles. Moreover, since it heats over about 3 hours, it fully dries and dehydrates even the inside of the apple skin 9. On the other hand, when the inside of the drying chamber 1 is depressurized to about 1/5 of the atmospheric pressure, the evaporation of the moisture contained in the apple skin 9 is greatly promoted, and the evaporated moisture is removed by the condenser 32 or the like. Since it is always removed, dry dehydration is further accelerated. Further, since the heated air in the drying cabinet 1 is refluxed after the gas-liquid separation, the supplied heat amount hardly escapes to the outside.

  Therefore, even by heating at 60 ° C. which is not so high, the inside of the apple skin 9 can be sufficiently dried and dehydrated, and further, drying is accelerated by depressurization and dehumidification of the drying atmosphere, so that the drying time can be greatly shortened. Further, since the dehumidified warmed air is recirculated into the drying chamber 1, there is little loss of warming heat energy, and the drying heat energy cost can be greatly reduced.

  Depending on the object to be dried, the temperature and pressure in the drying cabinet 1 can be combined differently from the above. That is, when the degree of decompression is increased or decreased, the temperature may be decreased or increased. As a result of the study, for example, when the pressure is reduced to 100 mmHg, the temperature is about 50 ° C., whereas when the pressure is reduced to 200 mmHg, the temperature is set to about 70 ° C., and when the pressure is reduced to 350 mmHg, the temperature Is set to about 80 ° C. In addition, the reduced-pressure low-temperature drying apparatus according to the present invention is not limited to the above-described objects to be dried, but also for drying and dehydrating materials such as chemicals, fertilizers, and synthetic resins that may cause discoloration, deformation, or alteration when heated to high temperatures. It is possible to apply.

  Agricultural products, their residues, or marine products can be efficiently dried and dehydrated in a short time without discoloration, deformation, and alteration, so that they can be widely used in industries related to moisture adjustment and drying treatment. .

It is the schematic block diagram which looked at the decompression low-temperature drying apparatus from the front. It is the schematic block diagram which looked at the drying warehouse from the right side. It is a perspective view of a heat pipe. It is sectional drawing of a heat pipe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Drying chamber 2 Pressure reducing means 23 Vacuum pump 3 Gas-liquid separation means 35 Blower fan 32 Condenser 323 Refrigeration unit 33 Condensate water recovery device 4 Horizontal shelf 5 Heat pipe 6 Boiler (heating source)
9 Apple skin (fruit residue)

Claims (4)

A drying cabinet, a decompression unit that depressurizes the inside of the drying cabinet, and a gas-liquid separation unit that separates moisture in the air in the drying cabinet,
The drying cabinet stores horizontal shelves on which objects to be dried are placed,
A heat pipe is provided under the horizontal shelf,
The heat pipe includes a pipe sealed with a refrigerant, and a heating means for heating the refrigerant,
The reduced-pressure low-temperature drying apparatus characterized in that the refrigerant is vaporized by the heating means, and the vaporized refrigerant dissipates heat and condenses on the inner peripheral surface of the pipe.       2. The reduced-pressure low-temperature drying apparatus according to claim 1, wherein the object to be dried is either an agricultural product or a marine product.       2. The reduced-pressure low-temperature drying apparatus according to claim 1, wherein the object to be dried is a residue of either fruit or vegetable. The heating means according to any one of claims 1 to 3, comprising a heating pipe that penetrates the pipe in the axial direction, and a heating source.
A reduced-pressure low-temperature drying apparatus characterized in that a liquid heated by the heating source circulates in the heating pipe.

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