JP2006118835A - Frozen matter dryer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a frozen matter dryer capable of controlling the temperature and humidity of drying air to be supplied to a drying chamber according to fluctuation of a load, and extending the set value zones of drying temperature and humidity. <P>SOLUTION: The dryer comprises the drying chamber 1 storing a frozen object to be dried 12, a circulating air passage 3 communicating with the drying chamber, a condenser 3 and an evaporator 4 arranged on the upstream side from the drying chamber within the circulating air passage, a refrigerant circuit A formed by connecting a variable-speed compressor 15 to the condenser and the evaporator, an auxiliary condenser 21 connected to the condenser of the refrigerant circuit in parallel to form an auxiliary refrigerant circuit B with the compressor and the evaporator, a flow-adjustable decompressing means 9 connected to the liquid side of the condenser and the auxiliary condenser, respectively, a flow regulating valve 7 connected to the gas side of the condenser, and a variable-speed blower 5 arranged in the vicinity of the evaporator and blowing drying air into the drying chamber from under to above to make the object to be dried flow. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a frozen material drying apparatus, for example, a frozen material drying apparatus for drying food such as frozen potatoes and carrots.

  A conventional frozen material drying apparatus is provided with a drying chamber for storing a frozen material to be dried, and a circulation air passage communicating with the drying chamber, and a condenser and evaporation upstream of the drying chamber in the circulation air passage. A refrigerant circuit is formed by connecting a compressor to the condenser and the evaporator via a refrigerant pipe outside the circulation air passage, while forming a refrigerant circuit in parallel with the condenser outside the circulation air passage. An auxiliary refrigerant circuit is formed by connecting a condenser, and drying air is blown upward from the bottom of the drying chamber by a blower provided between the condenser and the evaporator, and the frozen material to be dried is convected. When the blowout temperature of the condenser becomes a predetermined value or more, the auxiliary refrigerant circuit is operated to control the temperature of the drying chamber and dry. (For example, refer to Patent Document 1).

JP-T-3-504634 (2p lower left column 1 line-3p upper left column 3 line, drawing)

  Since the conventional frozen material drying apparatus is configured as described above, and the compressor and the blower are operated at a constant speed, the amount of drying air depends on the load fluctuation, that is, the amount of the material to be dried and the size of the weight. However, the temperature and humidity cannot be accurately controlled, and there are problems that the set values of the drying temperature and humidity are limited.

  This is because, when a constant speed compressor is used, the load decreases as drying progresses even if the initial temperature and the initial evaporation temperature of cold air in the middle part of the evaporator and the condenser are secured in the initial stage of drying. If cold air temperature and evaporation temperature fall, supply temperature may shift, and if the evaporation temperature falls too much, it will fall below the compressor use limit (lower limit). Because there is also.

  In addition, the temperature and humidity of the drying air are controlled by switching between the refrigerant circuit and the auxiliary refrigerant circuit, but the amount of heating of the condenser provided in the circulation air passage is determined by the size of the condenser, There is a problem that it is difficult to control the temperature and humidity of the drying air supplied to the drying chamber to predetermined values.

  The present invention has been made in order to cope with the above-described problems, and enables the temperature and humidity of the drying air supplied to the drying chamber to be controlled in accordance with load fluctuations, and the drying temperature. Another object of the present invention is to provide a frozen material drying apparatus capable of widening the set value zone of humidity.

  A frozen material drying apparatus according to the present invention is provided with a drying chamber for storing a frozen material to be dried, a circulation air passage communicating with the drying chamber, and an upstream side of the drying chamber in the circulation air passage. A condenser and an evaporator; a refrigerant circuit formed by connecting a variable speed compressor disposed outside the circulation air passage to the condenser and the evaporator through a refrigerant pipe; and condensation of the refrigerant circuit Connected to the condenser in parallel outside the circulation air passage, and forms an auxiliary refrigerant circuit together with the compressor and the evaporator, and the flow rate can be adjusted respectively connected to the liquid side of the condenser and the auxiliary condenser. Pressure reducing means, a flow rate adjusting valve connected to the gas side of the condenser, and the evaporator in the circulation air passage, and a drying gas directed from below to above in the drying chamber. A variable speed blower that blows and flows the material to be dried It is.

Since the frozen material drying apparatus according to the present invention is configured as described above, the humidity state and the wind speed state of the suction of the evaporator change from the heavy to-be-dried product at the initial drying stage to the light to-be-dried product at the final drying stage. However, since the speed of the compressor changes correspondingly, the evaporation temperature of the evaporator can be optimally controlled. Further, the set value zones for the temperature and humidity for freeze-drying can be widened.
In addition, a blower is provided on the suction side of the evaporator, and a forced draft system is used. Therefore, the lowest temperature part in the circulation air passage (the middle part between the evaporator and the condenser) becomes positive pressure, and heat enters from outside the circulation air passage. (Heat loss) can be reduced.

  Furthermore, since detection sensors are provided to detect the temperature and relative humidity of the supply air and the temperature and relative humidity of the return air, the drying of the object to be dried progresses from the humidity state of the return air in the initial stage to the humidity state. When the temperature and relative humidity of the return air drop, the flow rate adjustment corresponding to the change of the return air, the compressor, the temperature of the supply air from the condenser by controlling the rotation speed of the blower, and the cold in the middle part of the evaporator and the condenser The air temperature can be controlled to a predetermined value.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of the first embodiment. As shown in FIG. 1, a drying chamber 1 and a circulation air passage 2 communicating with the drying chamber 1 are formed. A floor plate 11 made of a porous plate is provided in the drying chamber 1 and is frozen on the floor plate 11. A to-be-dried object 12 such as food is stored.

In the circulation air passage 2, a condenser 3 and an evaporator 4 are disposed on the upstream side of the drying chamber 1, and a variable speed blower 5 is disposed on the suction side of the evaporator 4.
As will be described later, the air blown from the blower 5 blows drying air from below the floor plate 11 of the drying chamber 1 through the condenser 3 and the evaporator 4 to form convection in the drying chamber 1. Thus, the material to be dried 12 is made to flow in the drying chamber 1 and dried.

  Further, the condenser 3 and the evaporator 4 are provided on the further upstream side of the variable speed compressor 15 disposed outside the circulation air passage 2, the accumulator 6 and the flow rate control valve 7 located on the gas side of the condenser 3. A well-known refrigerant circuit A is formed by a refrigerant pipe 20 together with a solenoid valve 8 and a decompression means 9 such as an electric expansion valve located on the liquid side of the condenser 3 and a check valve 10 capable of adjusting the flow rate.

Further, an auxiliary condenser 21 arranged outside the circulation air passage 2, a pressure reducing means 22 such as an electric expansion valve, which can adjust the flow rate, and a check valve 23 are connected in parallel with the condenser 3 as shown in FIG. The auxiliary refrigerant circuit B is formed together with the container 4, the accumulator 6, and the variable speed compressor 15.
Reference numeral 24 denotes a variable speed blower provided in the auxiliary condenser 21.

  Further, a supply temperature and relative humidity detection sensor 25 is provided on the drying chamber 1 side of the condenser 3 in the circulation air path 2 so that the supply temperature and humidity target values can be set independently. Has been. Further, a detection sensor 26 for detecting the temperature and relative humidity of the return air is provided on the suction side of the evaporator 4.

In such a configuration, when the object to be dried 12 in the drying chamber 1 is dried, the refrigerant circuit A and the auxiliary refrigerant circuit B are operated, and air from the blower 5 is supplied toward the drying chamber 1.
The air blown from the blower 5 is cooled by the evaporator 4, heated by the condenser 3, supplied from below to the drying chamber 1 as drying air of −5 ° C. or less, and passes through the floor plate 11 made of a perforated plate to enter the drying chamber 1. Then, convection is formed, and the frozen material to be dried 12 is dried while flowing.

  Since the blower 5 is forced air flow, the lowest temperature portion in the circulation air passage 2 (intermediate portion between the evaporator 4 and the condenser 3) has a positive pressure, and heat intrusion (heat loss) from outside the circulation air passage is reduced. is doing.

  In the drying chamber 1 in the initial drying state, the material to be dried 12 is heavy, but at the end of drying, it becomes light and the load state varies. Along with this, the temperature and humidity of the return air fluctuate. This is read by the detection sensor 26, the drying state in the drying chamber 1 is estimated from the temperature and humidity of the return air, and supplied regardless of changes in the return temperature and humidity. The evaporation temperature of the evaporator 4 and the condensation temperature of the condenser 3 are controlled so that the temperature and humidity become the target set values.

For this purpose, the rotational speeds of the compressor 15 and the blowers 5 and 24 are controlled, and the openings of the flow control valve 7 and the decompression means 9 and 22 are adjusted to optimum values.
For example, if the ambient temperature of the auxiliary condenser 21 is 25 ° C., the condensation temperature is 40 ° C., the suction temperature of the condenser 3 is −40 ° C., and the condensation temperature is 0 ° C., a large amount of refrigerant moves to the condenser 3 side where the temperature is low. Inflow may cause an excessive reheat amount or a shortage of the refrigerant amount. Therefore, adjustment of the flow rate adjustment valve 7 changes the condensation temperature of the condenser 3 to eliminate the above-described problem.
As a result, the wind speed in the drying chamber 1 is also adjusted to an optimum value.

  If the condenser 3 is stopped by closing the solenoid valve 8 of the refrigerant circuit A and only the auxiliary refrigerant circuit B is operated, the drying air is only cooled by the evaporator 4. The to-be-dried object 12 is frozen. That is, drying and freezing can be switched by opening and closing the electromagnetic valve 8.

Further, if CO ₂ is used as the refrigerant in the refrigerant circuit A and the auxiliary refrigerant circuit B, the upper limit value of the condensation temperature is increased as compared with a normal refrigerant such as R404A. The temperature of the refrigerant can be set to about 50 ° C. to about 100 ° C., and the temperature setting zone can be widened, so that the target range of the object to be dried can be expanded and the drying speed can be increased. Therefore, the drying time can be shortened.

  In this embodiment, since the compressor 15 and the blowers 5 and 24 are variable speeds, the speed can be adjusted according to the output of the detection sensor 26. As a result, the evaporation temperature of the evaporator and the flow rate adjustment of the refrigerant circuit can be adjusted. The condensation temperature of the condenser can be easily controlled to an optimum value.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a schematic diagram showing the configuration of the second embodiment. In this figure, the same or corresponding parts as in FIG.

  A difference from FIG. 1 is that a partition plate 30 is provided between the condenser 3 and the blower 5 which are a part of the circulation air passage 2 and the circulation air passage 2 is divided into two routes in FIG. In addition to the evaporators 41 and 42, one further circuit having the same configuration as the pressure reducing circuit comprising the pressure reducing means 9 and 22 and the check valves 10 and 23 capable of adjusting the flow rate is provided and connected in parallel as shown in the figure. The connection point between the check valves 10 and 23 of one decompression circuit is connected to one evaporator 41, and the connection point between the check valves 10 and 23 of the other decompression circuit is connected to the other evaporator 42. Is a point.

  Further, the paths provided with the respective evaporators 41 and 42 are provided with dampers 31 and 32 on the suction side of the respective evaporators so that the air from the blower 5 can be passed or blocked by rotating each damper by 90 degrees. It has become. FIG. 2 shows a state where the damper 31 allows air flow and the damper 32 is shut off.

Further, the operation of the evaporators 41 and 42 is switched between the operation and the stop by adjusting the method of throttling the decompression means 9 and 22 of the decompression circuit in accordance with the flow and interruption of the dampers 31 and 32.
By configuring in this way, when one of the evaporators is frosted, it can be defrosted by heating, for example, by reversing hot gas in a state where it is switched to operate another evaporator. it can.
Therefore, even if the evaporator has frost formation, freeze-drying in the drying chamber 1 can be performed continuously, preventing deterioration of food quality and shortening the drying time.

  Since the frozen material drying apparatus of the present invention is configured as described above, it has the following characteristics in addition to the effects of the above-described embodiments.

1. Sublimation drying is performed in a frozen state, so there is almost no change in ingredients such as foods, loss of volatile components is small, and the original function, activity and form can be preserved as they are.
2. Since it is handled in a frozen and solidified state, the volume remains unchanged, foaming, separation, surface hardening, and tissue change do not occur, and a porous product is obtained. Therefore, the resilience when water is added is extremely good.
3. Since it is dried while maintaining a porous and three-dimensional structure, it is dehydrated uniformly and well from the inside, and the dryness is good.
4). There is also a method of vacuum freeze-drying, but since the atmospheric pressure is lowered to 0.8 _Torr or less, a vacuum pump is necessary, and energy consumption is increased. If the refrigerant system is used as in the present invention, the energy consumption can be reduced by 20 to 30% compared to vacuum drying.

It is the schematic which shows the structure of Embodiment 1 of this invention. It is the schematic which shows the structure of Embodiment 2 of this invention.

Explanation of symbols

1 Drying room, 2 Circulating air path, 3 Condenser, 4 Evaporator, 5 Blower,
7 Flow control valve, 8 Solenoid valve, 11 Floor plate, 12 Dried object,
9, 22 Depressurizing means with adjustable flow rate, 15 Compressor, 21 Auxiliary condenser,
A refrigerant circuit, B auxiliary refrigerant circuit.

Claims (6)

  A drying chamber for storing the object to be dried, a circulation air passage communicating with the drying chamber, a condenser and an evaporator disposed upstream of the drying chamber in the circulation air passage, and the condenser And a refrigerant circuit formed by connecting a variable speed compressor disposed outside the circulation air passage to the evaporator via a refrigerant pipe, and a condenser of the refrigerant circuit in parallel outside the circulation air passage. An auxiliary condenser that forms an auxiliary refrigerant circuit together with the compressor and the evaporator, a pressure-reducing means connected to the condenser and the liquid side of the auxiliary condenser, respectively, and a gas of the condenser And a flow regulating valve connected to the side, and disposed in the circulation air passage in the vicinity of the evaporator, allowing a drying gas to be blown into the drying chamber from below to allow the material to be dried to flow. A frozen material drying apparatus comprising a variable speed blower.   The frozen material drying apparatus according to claim 1, wherein the blower is disposed on a suction side of the evaporator.   3. The frozen matter drying apparatus according to claim 1, wherein an electromagnetic valve is connected upstream of a flow rate adjusting valve connected to the gas side of the condenser.   In the circulation air passage, a detection sensor for detecting the temperature and relative humidity of the supply air is provided on the drying chamber side of the condenser, and a detection sensor for detecting the temperature and relative humidity of the return air on the suction side of the evaporator The freezing according to any one of claims 1 to 3, wherein the number of revolutions of the compressor or the blower or the opening of the flow rate adjusting valve is controlled based on the output of each detection sensor. Product drying equipment.   A part of the circulation air passage is divided into a plurality of paths, and an evaporator is arranged in each path and connected in parallel, and a pressure reducing means capable of adjusting the flow rate is connected to each of the evaporators, and the flow rate can be adjusted. 5. The frozen matter drying apparatus according to claim 1, wherein one of the evaporators can be selectively used by controlling the pressure reducing means. _2. The frozen material drying apparatus according to claim 1, wherein CO ₂ is used as a refrigerant in the refrigerant circuit and the auxiliary refrigerant circuit.

Images