KR100246245B1 - Refrigerator-free freeze-drying system - Google Patents

Abstract

The present invention relates to an improved vacuum freeze drying system using a booster instead of using a freezer which is an essential component of the prior art vacuum freeze drying system.

The vacuum freeze drying system 100 according to the present invention includes a vacuum chamber 10 having a plurality of plates 14 capable of storing a material 12 to be dried and heating it to an appropriate temperature, and the vacuum chamber 10. A mechanical booster 20 used to provide predetermined pressure and temperature conditions to the condenser, a condenser 30 for condensing water vapor sublimed in the vacuum chamber 10 and passing through the mechanical booster 20; Discharge means such as a vacuum pump 40 for adding or discharging gas, such as air that is not condensed in the condenser 30, to the atmosphere, and a pump 50 for discharging water condensed in the condenser 30, etc. It is included. In addition, since the temperature of the water vapor flowing into the condenser 30 is about 41.4 ° C., the water vapor may be condensed using water at room temperature of about 20 ° C.

Therefore, by using the vacuum freeze-drying system according to the present invention, it is possible to easily overcome the problems caused by the use of the refrigerator, that is, the decrease in the coefficient of performance of the freezer, the performance deterioration due to freezing inside the condenser.

Description

Vacuum freeze drying system that does not require a freezer {Refrigerator-free Freeze-drying System}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum freeze drying system used in the general machinery field and the food industry, in particular, maintaining the state in a chamber for storing a material to be dried below a triple point of water and sublimating water contained in the material. And a vacuum freezing system for drying by removing the material.

The conventional vacuum freeze-drying system shown in FIG. 1 generally includes a vacuum chamber 1 containing a drying object or material 6, a condenser 2 for condensing water vapor generated from the material 6, and the water vapor. To cool the condenser 2 to generate condenser 2 and to provide the condenser 2, a pump 4 for discharging condensed water, and the vacuum chamber 1 to be kept in a vacuum state and not condensed. It consists of a vacuum pump 5 for adding or discharging gas which does not.

Since the water vapor flowing into the condenser 2 is about 0 ° C., which is similar to the triple point temperature of water, the condenser must be kept at a low temperature of about −50 ° C. in order to condense it. (3) is necessary as an essential component.

In the case of using the refrigerator 3, the outer wall of the condenser 2 condenses and freezes water vapor flowing from the material to be dried 6 to form an ice layer, and thus a kind of thermal insulation layer that prevents heat transfer between the condenser and the water vapor. As a result, the heat transfer efficiency of the condenser is significantly reduced. In order to heat the condenser to melt the ice layer frozen on the outer wall of this condenser, the freeze drying process must be stopped during the heat. As a result, the pressure in the vacuum chamber 1 becomes higher than the triple point pressure, and the freeze-drying material 6 is melted instead of sublimed, thereby causing damage to the freshness of the material. Furthermore, in the case of producing low temperature cold heat which can maintain the temperature of the condenser 2 at about -50 ° C, the coefficient of performance of the refrigerator 3 is significantly lowered, so that the energy consumption of the whole system is considerably increased and the operating cost is increased. Will rise. In addition, there is a possibility that the sublimed water vapor in the vacuum chamber 1 may not be completely condensed in the condenser 2 and a part of the water may flow into the vacuum pump 5, thereby degrading the performance of the vacuum pump over time. Will be.

On the other hand, a method of discharging the non-condensable gas and the uncondensed water vapor by using a steam ejector (ejector) instead of a vacuum pump may be attempted, but the use of the freezer (3) is essential because the steam ejector is not very high compression ratio.

Accordingly, the present invention provides a number of disadvantages of the vacuum freeze drying system according to the prior art, in which the refrigerator is an essential component as described above, namely (1) the coefficient of performance of the refrigerator used to generate low temperature cold heat on the order of -50 ° C. (2) deterioration of the heat transfer efficiency of the condenser by the ice layer frozen on the outer wall of the condenser, (3) damage of the drying object due to heating for melting the ice layer, and (4) vacuum pump of uncondensed water vapor. It is an object of the present invention to provide an improved vacuum freeze drying system that overcomes a number of shortcomings such as deterioration of the vacuum pump due to inflow into it.

The improved vacuum freeze drying system according to the present invention is characterized by the use of a mechanical booster in place of the freezer, taking into account that many disadvantages of the prior art drying system originate from the freezer, which is an essential component.

Hereinafter, with reference to Figure 2 schematically showing a vacuum freeze drying system according to the present invention will be described in detail the technical configuration and operation of the present invention.

1 is a schematic diagram of a standard vacuum freeze drying system according to the prior art.

2 is a schematic diagram of a vacuum freeze drying system according to the present invention.

<Description of the code | symbol about the principal part of drawing>

10: vacuum chamber

12: material to be dried

20: mechanical booster

30: condenser

40: vacuum pump

2, the vacuum freeze drying system 100 according to the present invention comprises a vacuum chamber 10 having a material to be dried 12 and a plurality of heating means, for example, a heatable material receiving plate 14, and the vacuum. A mechanical booster 20 which is used not only to depressurize the chamber 10 to a condition similar to that below the triple point state of water, but also pressurize the water vapor discharged from the chamber 10 to a condenser 30 by pressurizing it at a significant compression ratio, The condenser 30 for condensing the compressed water vapor from the mechanical booster 20 and the vacuum chamber 10 is depressurized and gas or air that is not condensed in the condenser 30 is added or discharged to the atmosphere. Vacuum pump 40 for discharging water and pump 50 for discharging water condensed in the condenser 30.

The vacuum chamber 10 has a plurality of plates 14 for storing the material 12 to be dried therein, the plates 14 being heated to a predetermined temperature during operation of the drying system 100. Serves as a heating plate. In addition, the vacuum chamber 10 is in fluid communication with the condenser 30 via a mechanical booster 20.

The booster 20 is used to evacuate, ie, depressurize, the vacuum chamber 10 using the motor 22, and pressurize the water vapor generated from the vacuum chamber 10 to be discharged to the condenser 30. Function. Since the booster 20 may achieve a higher compression ratio than the vapor ejector, the pressure of the water vapor introduced into the booster 20 is pressurized (insulated compression) under a predetermined pressure condition unlike a drying system according to the related art. 30) can be sent out. That is, in the drying system according to the prior art using a refrigerator, water vapor flowing into the condenser has a pressure of 4.58 Torr and a temperature of 0.01 ° C., whereas in the drying system according to the present invention, the pressure is 60 Torr by using a mechanical booster. In this case, the saturation temperature of the water vapor is 41.4 ° C. Therefore, in order to condense the water vapor of about 41.4 ° C., since the water vapor can be easily condensed even at room temperature, that is, ordinary water of about 20 ° C., the low temperature of about −50 ° C. generated by the freezer as in the prior art. It is not necessary to condense the water vapor using cold heat.

Moreover, using the mechanical booster 20 instead of using a freezer does not produce ice layers frozen on the outer wall of the condenser of the vacuum freeze drying system according to the prior art, thus intermittently melting the ice layer formed on the outer wall of the condenser. No additional heating work is required. Thus, it is possible to continuously operate the condenser. In addition, the deterioration phenomenon of the material 12 to be dried, which may be generated by heating the condenser, can be further prevented.

As described above, the mechanical booster 20 has a function of maintaining the chamber 10 in a vacuum state of, for example, 4.58 Torr or less by exhausting water vapor generated from the material to be dried 12 from the vacuum chamber 10, Pressurizes the water vapor flowing into the condenser 30 in a predetermined state so as to condense the water vapor introduced into the condenser 30 even using water of about 20 ° C., and sends the water to the condenser 30. It must be done at the same time. In other words, since the water vapor exhausted from the vacuum chamber 10 is 4.58 Torr (0.01 ° C), in order to condense the water vapor using water at a room temperature of about 20 ° C, the water vapor is at least 17.5 Torr (at this time saturation). The temperature should be introduced into the condenser above 20 ° C). Therefore, the booster 20 should be able to compress the water vapor to 23 Torr (saturation temperature 24.4 ℃) or more because the compression ratio should be at least 5 or more. The temperature of the water used as the cooling water in the condenser 30 does not necessarily need to be 20 ° C., and water of any temperature capable of condensing the water vapor introduced from the booster 20 may be used.

In the present invention, for example, two boosters corresponding to the models 5511 and 3210 of Tuthill Corp., USA, which are driven by 10 horsepower and 3 horsepower motors, can be used. By using them in series, a compression ratio of about 20 can be achieved. The booster of the 5511 model has a compression ratio of about 5 and can pressurize the steam at a pressure of 3 Torr to 15 Torr, and the booster of the 3210 model can pressurize the steam pressure from 15 Torr to 60 Torr continuously with a compression ratio of 4 have. 2 illustrates a mechanical booster and a related pump one by one, but a plurality of boosters may be connected and used as necessary.

On the other hand, the condenser 30 is connected to a pump 50 for discharging condensed water and a vacuum pump 40 for discharging or bleeding non-condensed gas into the atmosphere. The vacuum pump 40 is used to vacuum the pressure of the vacuum chamber 10 to about 20 Torr during the initial operation of the present drying system 100. On the other hand, after the system is in normal operation, in order to maintain the vacuum in the vacuum chamber 10, the booster 20 maintains the vacuum below the pressure of 4.58 Torr by evacuating water vapor in the vacuum chamber 10, so that the vacuum The pump 40 does not need to be operated. However, it is necessary to operate the vacuum pump 40 intermittently to prevent accumulation of non-condensable gases such as air generated from the freeze-drying material 12 and the like in the condenser. Therefore, since the vacuum pump 40 performs only a simple bleed or discharge function of the non-condensable gas from the condenser 30, problems such as deterioration of the performance of the vacuum pump due to inlet water vapor can be easily overcome.

The pump 50 is used to drain condensed water from the condenser 30 and may be replaced by conventional means such as a drain valve.

Now, the operation method and principle of the vacuum freeze drying system according to the present invention will be described in detail.

First, a vacuum pump 40 is used to maintain a vacuum in the vacuum chamber 10 containing the material to be dried 12 at a pressure of approximately 20 Torr, and then the booster 20 is used to maintain the triple pressure of water in the chamber. Vacuum to a state corresponding to (e.g., 4.58 Torr pressure and 0.01 ° C temperature). Subsequently, the heating plate 14 in the chamber 10 is heated to an appropriate temperature to directly sublimate moisture contained in the material to be dried 12 with water vapor. As mentioned above, the sublimed water vapor is compressed by a mechanical booster 20 to a pressure of 60 Torr, so that the water vapor is maintained at a saturation temperature of 41.4 ° C. for 60 Torr pressure. The water vapor then flows into the condenser 30.

Since the water vapor flows into the condenser 30 at a temperature of 41.4 ° C., the water vapor is condensed using water at room temperature of about 20 ° C. Water generated by condensation of water vapor sublimed from the material to be dried 12 is discharged to the outside through the pump 50, and gas remaining in the condenser 30 without being condensed is discharged to the atmosphere by the vacuum pump 40. Or additionally. As described above, the vacuum pump 40 is only used to initially evacuate the vacuum chamber 10 to a pressure of approximately 20 Torr during the initial operation of the system 100. Thereafter, maintaining the vacuum chamber 10 at a pressure of 4.58 Torr is the mechanical booster 20, and the vacuum pump 40 is only used intermittently to remove the non-condensable gas that accumulates in the condenser 30. There is no possibility of deterioration of the performance of the vacuum pump 40 as in the prior art, in which water vapor which is not condensed from the 30 is introduced into the vacuum pump 40.

As mentioned above, the vacuum freeze drying system according to the present invention using a booster instead of using a freezer does not require energy to obtain low temperature cold heat, such as -50 ° C, which the freezer of the prior art system must provide to the condenser. As a result, the energy cost is significantly reduced. In addition, no ice layer is formed on the outer wall of the condenser, which not only enables continuous system operation but also prevents deterioration of the material to be dried, which may be caused by heating the condenser surface, thereby preventing fine quality and long-term storage of the material. It becomes possible. This can also contribute to price stabilization of agricultural products in industrial terms.

Meanwhile, the vacuum freeze drying system according to the present invention can be used for drying and storing various materials such as drugs, microorganisms and fruits as well as drying foods.

Claims (3)

A vacuum dry freezing system for drying a material to be dried, A vacuum chamber 10 having a heating means 14 for storing the material to be dried 12 and heating it to a predetermined temperature; With the condenser 30, It is provided between the vacuum chamber 10 and the condenser 30, is operated to maintain the vacuum chamber 10 at a predetermined first pressure and a first temperature, sublimated water vapor from the material to be dried 12 A mechanical booster 20 for changing the to a predetermined second pressure and a second temperature and then supplying it to the condenser 30, Is in fluid communication with the vacuum chamber 10 and the condenser 30, and operates to evacuate the pressure in the vacuum chamber 10 below a predetermined pressure upon initial operation of the drying system. And the vacuum pump 40 to perform the function of discharging the gas that is not condensed in the condenser 30 to the atmosphere, And a means (50) for discharging the water formed by condensation of the water vapor to the outside. The vacuum freeze drying system according to claim 1, wherein the condenser (30) is a condenser having water at room temperature of 20 ° C as cooling water. The vacuum as claimed in claim 1, wherein the first pressure is 4.58 Torr, the second pressure is 60 Torr, the first temperature is 0.01 ° C., and the second temperature is 41.4 ° C. 4. Freeze drying system.

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