WO2002073110A1

WO2002073110A1 - Nitrogen-controlled freezing type dehumidifying and drying apparatus

Info

Publication number: WO2002073110A1
Application number: PCT/KR2002/000341
Authority: WO
Inventors: Hong-Cheor Hoang
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-03-02
Filing date: 2002-02-28
Publication date: 2002-09-19
Anticipated expiration: 2003-09-02
Also published as: KR100413517B1; KR20020070701A

Abstract

The present invention relates to a nitogen-controlled freezing type dehumidifying and drying apparatus which includes a drying chamber in which an air suction line and a nitrogen supply line of a nitrogen generator are connected for thereby receiving a nitrogen gas generated by a nitrogen generator and maintaining a nitrogen gas environment therein, an external air inlet pipewhich is connected between a suction side automatic valve and a nitrogen supply unit installed in an air suction which connects the drying chamber and the nitrogen generator for thereby sucking an external air and generating a nitrogen at the time when a nitrogen generator is initially operated for changing the interior of the drying chamber to a nitrogen gas environment, and an opening and closing valve which is installed in the external air inlet pipe for thereby controlling a suction and disconnecting operation of an external air.

Description

NITROGEN-CONTROLLED FREEZING TYPE DEHUMIDIFYING AND DRYING APPARATUS

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a nitrogen-controlled freezing type dehumidifying and drying apparatus, and in particular to a nitrogen-controlled freezing type dehumidifying and drying apparatus which is capable of preventing a seasoning and oxidation deterioration of an agricultural and marine product under a nitrogen gas environment and quickly drying the products.

2. Description of the Background Art

Generally, in order to dry an agricultural product such as a jujube, yam, etc. and a marine product such as a dried fish slice, etc., a low temperature drying method is used for preventing a deterioration of the above products.

In the conventional art, in a drying apparatus capable of drying a product, a freezer is installed in the interior of a drying chamber for preventing a deterioration of a food, and then the freezer is driven, so that the interior of the drying chamber is maintained in a low temperature state for thereby effectively drying a food.

However, since the air in the interior of the drying chamber is cooled to below 15°C using a freezer and then is circulated therein, so that it is possible to prevent a deterioration of the food. In this case, a food drying time is increased. In order to have a low temperature state in the drying chamber, the freezer is frequently operated, so that the driving time of the freezer is increased. Since the operation cost of the drying apparatus is increased by the operation time of the freezer, the drying cost of the food is increased. In particular, since the food is dried for a long time under an oxygen gas environment in the temperature of the drying chamber is below 15°C, the colour of the food may be changed or oxygen- deteriorated. Furthermore, the seasoning process of the food may be performed during the low temperature drying process.

In the case of the agriculture and marine products, when the concentration of the oxygen is high, since the colour is changed or oxygen-deteriorated, the CA(Controlled Atmosphere) storing method in which the concentration of the oxygen is decreased, and the concentration of CO2 is increased in the atmosphere, is used. The above CA storing method is properly used for storing the fruits and vegetable at a low temperature(below 13°C) for a long time. However, the above CA method is not proper for drying the foods.

Namely, in the above CA storing method, the temperature of the drying chamber is decreased to below 13°C using the freezer for thereby preventing a dehumidifying phenomenon of the storing food. The above CA storing method may be properly used for storing the fruits or vegetable which need a fresh state for a long time. However, the above CA method is improper for storing the food which needs a dehumidifying and drying operation such as a jujube, yam, etc. or a marine product such as a dried codfish slice, a dried walleye pollack slice, and a dried cuttlefish slice.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a dehumidifying and drying apparatus capable of properly drying a food which needs a dehumidification. It is another object of the present invention to provide a nitrogen-controlled freezing type dehumidifying and drying apparatus which is capable of forming a nitrogen gas environment in the interior of a drying chamber, preventing an oxidation deterioration of a food and a seasoning state of the same, controlling the temperature of the drying chamber from a low temperature of 13°C to a high temperature of 40°C, condensing and drying the air of the interior of the drying chamber for thereby implementing a quick drying operation of the food.

It is another object of the present invention to provide a nitrogen-controlled freezing type dehumidifying and drying apparatus which is capable of preventing a nitrogen gas environment air from being discharged to the outside when discharging a condensing water which is generated when an interior air of the drying chamber is cooled in a freezer installed in the interior of the drying chamber for thereby continuously maintaining a nitrogen gas environment in the interior of the drying chamber. To achieve the above objects, there is provided a nitrogen-controlled freezing type dehumidifying and drying apparatus which includes a drying chamber in which an air suction line and a nitrogen supply line of a nitrogen generator are connected for thereby receiving a nitrogen gas generated by a nitrogen generator and maintaining a nitrogen gas environment therein, an external air inlet pipe which is connected between a suction side automatic valve and a nitrogen supply unit installed in an air suction line which connects the drying chamber and the nitrogen generator for thereby sucking an external air and generating a nitrogen at the time when a nitrogen generator is initially operated for changing the interior of the drying chamber to a nitrogen gas environment, and an opening and closing valve which is installed in the external air inlet pipe for thereby controlling a suction and disconnecting operation of an external air wherein a nitrogen-controlled freezing type dehumidifying and drying apparatus is capable of storing an agricultural and marine product in the interior of a drying chamber in which a freezer is installed.

In addition, in the interior of the freezer installed in the interior of the drying chamber, a condensed water tank is installed in a discharging pipe of a condensed water collector for collecting a water condensed by a heat exchanging operation by an evaporator, and a water level sensor is installed in a condensed water tank in such a manner that the discharging operation of the condensed water is stopped at a position higher than a connection portion of a drain pipe by detecting the level of the condensed water when discharging the condensed water stored in the condensed water tank.

The water level sensor includes a low water level detection rod for detecting a low water level in such a manner that the discharging operation of the condensed water is stopped at a low water level slightly higher than that of a connection portion of the drain pipe when discharging the condensed water stored in the condensed water tank, a high water level detection rod for detecting a high water level in such a manner that a condensed water is discharged when the condensed water stored in the condensed water tank reaches at a high level at which the condensed water is discharged, and a condensed water detection rod which is extended to a portion lower than the low water level detection rod for thereby detecting as to whether the condensed water is stored in the condensed water tank.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become better understood with reference to the accompanying drawings which are given only by way of illustration and thus are not limitative of the present invention, wherein; Figure 1 is a view illustrating the construction of a nitrogen-controlled freezing type dehumidifying and drying apparatus according to the present invention;

Figure 2 is a circuit diagram illustrating a connection structure of a drying chamber and a nitrogen generator according to the present invention;

Figure 3 is a view illustrating an inner construction of a freezer according to the present invention; and

Figure 4 is a view illustrating a condensed water tank of a freezer according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments of the present invention will be explained with reference to the accompanying drawings.

Figure 1 is a view illustrating the construction of a nitrogen-controlled freezing type dehumidifying and drying apparatus according to the present invention, Figure 2 is a circuit diagram illustrating a connection structure of a drying chamber and a nitrogen generator according to the present invention, Figure 3 is a view illustrating an inner construction of a freezer according to the present invention, and Figure 4 is a view illustrating a condensed water tank of a freezer according to the present invention.

In the drawings, reference numeral 1 represents a drying chamber. The drying chamber 1 is sealed for preventing the air therein from being discharged to the outside. The bottom wall and ceiling are insulated. In addition, an entrance door is formed in such a manner that a worker comes in and out, and a storing food is loaded and unloaded.

A freezer 2 is installed in one side of the interior of the drying chamber 1 for thereby circulating the internal air of the drying chamber.

A suction port 21 is installed in a lower portion of the freezer 2 for sucking the air in the lower side of the interior of the drying chamber 1 , and a blowing unit 22 is formed in the upper portion of the freezer 2 for blowing the air in the upper direction of the interior of the drying chamber 1.

A filter 21a is installed in the suction port 21 for filtering a foreign substance in the air such as a dust, etc., and a fan 22a is installed in the blowing unit 22 for circulating the air.

In the freezer 2, an evaporator 23 is installed for cooling the air when a liquefied refrigerant is evaporated, and a condenser 24 is installed for radiating the heat when liquefying the evaporated refrigerant. The moisture is condensed and removed based on a heat exchanging operation of the evaporator 23 for thereby implementing a cooling effect. The dried air cooled by the evaporator 23 is heated to 13~40°C while the air passes through the condenser 24. In addition, a sub-condenser 24a is installed in the outer portion of the drying chamber 1 for discharging the heat generated when liquefying the evaporated refrigerant to the outside in order to prevent the air in which the moisture is condensed and removed by the evaporator of the freezer 2 from being heated to 13~40°C while the air passes through the condenser 24. In a state that the inner temperature of the drying chamber 1 is decreased to below zero, when the freezer 2 is operated, a trouble may occur. Therefore, a heater 25 is installed for increasing the inner temperature of the freezer when first driving the freezer 2 in the winter time. The above heater 25 is temporarily operated for a certain time before the freezer is first operated, and the inner temperature of the freezer 2 is increased to a certain degree so that a trouble does not occur in the freezer, and then the operation of the freezer 2 is stopped. In the freezer 2, the air is sucked from the inner lower side of the drying chamber 1 through an air suction port 21 formed in the lower portion of the same, and then the moisture in the air is removed based on a heat exchanging operation of the evaporator 23 as a condensed water, and the dried cooling air is transferred to the condenser 24 and is heated to a proper temperature. In addition, the air in the interior of the drying chamber 1 is circulated by blowing the air in the upper direction of the interior of the drying chamber 1 through the blowing unit 22.

A circulation partition 3 is horizontally installed in the inner upper portion of the drying chamber 1 at a height slightly lower than that of the blowing unit 22 of the freezer 2, so that the air blown from the air blowing unit 22 is circulated from the upper side to the lower side of the drying chamber 1 for thereby implementing an efficient convection current. In addition, a sub-blowing fan 4 is installed in the upper surface of the circulation partition 3, so that the air blown by the blowing unit 22 of the freezer 2 is moved in the opposite direction. In addition, a plurality of drying racks 5 are installed in the bottom of the drying chamber 1 for putting the storing food thereon.

A vacuum pump 6 and a nitrogen generator 7 are separately installed outside the drying chamber 1.

The vacuum pump 6 includes a vacuum pipe 61 for sucking the air of the interior of the drying chamber 1 , and a discharging pipe 62 for discharging the sucked air to the outside for thereby implementing a vacuum state in the interior of the drying chamber. A valve 63 is installed in the vacuum pipe 61.

The nitrogen generator 7 generates N₂ in the air and discards O₂, CO₂ and other gases. As shown in Figure 2, an air compressor 720, a check valve 721 , an air drier 722, a first manometer 723, a running water separator filter 724, a fine dust filter 725, a pressure adjusting valve 726, a pressure adjusting bolt 727, a second manometer 728, a muffler 729 and a plurality of valves(not shown) are sequentially installed from an air suction line 72 connected with the drying chamber with respect to the nitrogen generator 71 which is capable of generating N₂ in the air and discarding other gases. A plurality of stop valves 731 , 732 and 733 are installed in the nitrogen supply line 73 connected for thereby supplying a nitrogen to the drying chamber 1. A suction side automatic valve 74 is installed in the air suction line 72 between the drying chamber 1 and the air compressor 721. A supply side automatic valve 75 is installed in the nitrogen supply line 73 between the drying chamber 1 and the stop valves 731 and 732. The nitrogen generator 7 is capable of extracting a nitrogen of 99.9% in the air and is constituted in the same manner as the conventional nitrogen generator. Therefore, the detailed description of the same is omitted.

An external air inlet pipe 8 is connected between the suction side automatic valve 74 and the air compressor 721 which are installed in the air suction line 72 connectδing the drying chamber 1 and the nitrogen generator 7 for thereby sucking an external air, and an opening and closing valve 81 is installed in the external air inlet pipe, so that a nitrogen is generated by introducing an external air when making a nitrogen gas environment in the interior of the drying chamber 1 for thereby supplying a nitrogen into the drying chamber 1. In the drying chamber 1 , a pressure sensor 11 is installed for detecting the inner pressure of the nitrogen gas environment, and a safety valve 12 is installed for discharging an over pressure in the case that an inner pressure of the drying chamber is above a certain level.

The present invention is basically directed to preventing an air in the drying chamber 1 , namely, a nitrogen gas from being discharged to the outside when discharging the condensed water condensed by the evaporator 23 of the freezer 2 which is installed in one inner side of the drying chamber 1 and is capable of circulating the air.

A condensed water tank 27 stores and discharges the condensed water discharged from the condensed water collector 26 which collects a water condensed by the evaporator 23 installed in the interior of the freezer 2. A water level sensor 28 is installed in the interior of the condensed water tank for thereby controlling a discharging operation of the nitrogen gas and discharging the condensed water.

A discharging pipe 26a is connected with an upper portion of the condensed water tank 27 for thereby discharging the condensed water from the condensed water collector 26, and a drain pipe 27a is connected with a lower portion of the same for discharging the stored condensed water.

The water level sensor 28 includes a low water level detection rod 28a capable of detecting a proper water level in which the condensed water stored in the condensed water tank 27 is slightly higher than that of the connection portion of the drain pipe 27a, a high water level detection rod 28b for detecting a proper water level in which the condensed water is higher than the low water level detection rod 28a and is lower than the connection portion of the discharging pipe 26a, and a condensed water detection rod 28c which is downwardly extended longer than the low water level detection rod 28a and is capable of detecting as to whether the condensed water is stored in the condensed water tank 27. Each detection rod is connected with an electronic or electric circuit in such a manner that the signals corresponding to the detection of the condensed water are transferred to a controller(not shown), and the automatic valve 27b installed in the drain pipe 27a is opened and closed based on a signal of each detection rod.

The operation of the present invention will be explained with reference to the accompanying drawings.

A plurality of drying racks 5 in which the foods are stored in multiple stages are inputted into the interior of the drying chamber 1 , and the interior of the drying chamber 1 is changed to the nitrogen gas environment. The above operation will be explained.

The vacuum pump 6 installed outside the drying chamber 1 is driven, so that the interior of the drying chamber 1 is vacuumed to have a vacuum level of 4Torr, and then the valve 63 of the vacuum pipe 61 is opened and closed.

After the interior of the drying chamber 1 is vacuumed, the nitrogen generator 7 is driven for changing the interior of the drying chamber to a nitrogen gas environment. At this time, since the interior of the drying chamber is in a vacuum state by the vacuum pump 6, the air is lack for generating the nitrogen gas. In the initial operation stage for first generating the nitrogen generator 7 for changing the interior of the drying chamber 1 to the nitrogen gas environment, it is impossible to generate the nitrogen based on a lack of the air which exists in the interior of the drying chamber 1 of the vacuum environment.

Therefore, in order to first change the interior of the drying chamber 1 of the vacuum environment to the nitrogen gas environment, since the air having a lot nitrogen gas, namely, the air outside the drying chamber 1 must be introduced, in the initial operation stage of the nitrogen generator 7, the inlet side automatic valve 74 installed in the air suction line 72 connecting the drying chamber 1 and the nitrogen generator 7 is opened and closed, and the opening and closing valve 81 of the opening and closing valve 81 of the external air inlet pipe 8 is opened, and the nitrogen generator 7 is driven, so that the external air is sucked into the air suction line 72 through the external air inlet pipe 8, whereby the nitrogen generator 7 generates a nitrogen of 99.9%. When driving the nitrogen generator 7, the supply side automatic valve 75 installed in the nitrogen supply line 73 is opened, and the nitrogen generated in the nitrogen generator 7 is supplied into the interior of the drying chamber 1 , and the nitrogen is supplied based on a continuous operation of the nitrogen generator 7 for thereby changing the interior of the drying chamber 1 to the nitrogen gas environment. At this time, the atmospheric pressure of the interior of the drying chamber 1 is 0.001 ~0.05/Kgf/cm² by the nitrogen supplied into the interior of the drying chamber 1 of the vacuum environment. The atmospheric pressure of the interior of the drying chamber 1 is slightly higher than the atmospheric pressure in the air for the reason that it is possible to easily change the interior of the drying chamber 1 to the nitrogen gas environment. In addition, the concentration of the nitrogen gas in the interior of the drying chamber 1 is about 85-99%.

The interior of the drying chamber 1 is changed to the vacuum environment, and the external air is introduced for thereby generating a nitrogen using the nitrogen generator 7, and the generated nitrogen gas is transferred to the drying chamber 1. When the inner pressure of the drying chamber is a desired pressure and a nitrogen gas environment of a desired concentration, the suction side automatic valve 74 and the supply side automatic valve 75 are closed, and the operation of the nitrogen generator 7 is stopped. After the operation of the nitrogen generator 7 is stopped, when the freezer

2 installed in the interior of the drying chamber 1 is driven, the internal air of the drying chamber 1 of the nitrogen gas environment is circulated. The freezer 2 sucks the air of the nitrogen gas environment and cools the same. The evaporator

23 condenses and removes the moistures in the air. The dried cooled air from which the moisture is removed by the evaporator passes through the condenser

24 and is heated a heat exchanging operation with the condenser and is blown to the upper portions in the interior of the drying chamber 1 through the blowing unit 22.

The air which is cooled by the evaporator 23 of the freezer 2 and is heated while passing through the condenser 24 has a temperature of 13~40°C. If the inner temperature of the drying chamber 1 is below 13°C, the drying operation of the food is delayed, and in the case of above 40°C, since the food may be deteriorated, the heating temperature of the air which passes through the condenser 24 of the freezer 2 is preferably 13~40°C.

Since the air which circulates through the lower side of the interior of the drying chamber 1 is sucked through the suction port 21 of the lower portion of the freezer 2, and the air which is heated to a proper temperature is blown by the blowing unit 22 installed in the upper portion, the air of the nitrogen gas environment of the interior of the drying chamber has a proper temperature for drying the food, so that the circulation is performed from the upper side to the lower side. Therefore, the dehumidifying and drying operation of the foods stored in the drying rack 5 in multiple stages is efficiently performed.

When drying the stored foods by driving the freezer 2 and circulating the air of the nitrogen gas environment, as the time is passed, when the nitrogen concentration becomes below a set concentration, in a state that the suction side automatic valve 74 of the air suction line 72 and the supply side automatic valve 75 of the nitrogen supply line 73 are opened, the nitrogen generator 7 is re-driven, and the nitrogen is regenerated in such a manner that the air of the nitrogen gas environment in the interior of the drying chamber 1 is circulated for thereby changing the interior of the drying chamber 1 to a nitrogen gas environment. Therefore, at the initial time in which the interior of the drying chamber 1 is changed from the vacuum environment to the nitrogen gas environment, an external air is introduced. After the nitrogen gas is generated, the nitrogen gas is repeatedly generated using the nitrogen gas environment air of the interior of the drying chamber 1.

When discharging the water condensed by the evaporator 23 of the freezer 2, the nitrogen gas of the interior of the drying chamber 1 is not discharged, and only the condensed water is discharged. The above operation will be explained in detail as follows.

The moisture included in the air is condensed by the evaporator 23 and is collected in the condensed water collector 26 while the nitrogen gas environment flown into the freezer 2 is cooled by a cooling operation of the evaporator 23. The condensed water collected in the condensed water collector 26 is stored in the condensed water tank 27 through the discharging pipe 26a. Since the condensed water collector 26 is exposed in the interior of the freezer 2, the air of the nitrogen gas environment flown into the interior of the freezer 2 is flown into the condensed water tank 27 together with the condensed water. The condensed water detection rod 28c of the water level sensor 28 installed in the interior of the condensed water tank 27 transmits the signals to the controller(not shown) in the case that there is not change in the condensed water of the condensed water tank 27 or the condensed water is stored at a level lower than the connection portion in which the drain pipe 27a is connected. Therefore, the controller closes and opens the automatic valve 27b. Therefore, even when the air of the nitrogen gas environment is flown into the condensed water than 27 together with the condensed water, the air of the nitrogen gas environment is not discharged to the outside. When the water condensed by the evaporator 23 is continuously flown into the condensed water tank 27, and reaches at the high water level detection rod 28b, the controller which received the signal opens the automatic valve 27b for thereby discharging the condensed water through the drain pipe 27a. When the condensed water is discharged and reaches at the lower portion of the low water level detection rod 28a, the controller closes the automatic valve 27a for thereby stopping the discharging operation of the condensed water. When the water condensed by the evaporator 23 reaches a discharging proper water level, the water level sensor 28 installed in the condensed water tank 27 discharges the condensed water. When the condensed water is discharged and reaches at a proper water level higher than the connection portion of the drain pipe 27a, the discharging operation of the condensed water is stopped. Even when the air of the nitrogen gas environment is flown into the interior of the condensed water tank 3 together with the condensed water, the nitrogen gas is not discharged to the outside. Therefore, it is possible to maintain a nitrogen gas environment in the interior of the dehumidifying and drying chamber 1 for a long time.

As described above, in the present invention, at the initial stage in which the interior of the drying chamber is changed to a vacuum environment, since an external air is introduced, it is possible to easily generate a nitrogen gas. In addition, it is possible to change the interior of the drying chamber to a nitrogen gas environment of a set pressure and concentration for a short time. After the interior of the drying chamber is changed to a nitrogen gas environment using an external air, when the nitrogen gas environment of the interior of the drying chamber is decreased to below the set level, the nitrogen generator is re-driven, so that it is possible to continuously maintain a nitrogen gas environment in the interior of the drying chamber. In addition, the nitrogen gas is not discharged to the outside when discharging the condensed water which is generated by the evaporator while the freezer installed in the interior of the drying chamber heats the nitrogen gas environment air of the interior of the drying chamber to a temperature of 13~40°C which is proper for the dehumidifying condition of the foods and is circulated. Therefore, it is possible to maintain a nitrogen gas environment of the set concentration in the interior of the drying chamber. The interior of the drying chamber is changed to a nitrogen gas environment for thereby stopping the seasoning operation of the foods stored in the interior of the drying chamber, and it is possible to quickly dehumidify without oxidation, and it is possible to enhance the quality of the dried foods.

As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the meets and bounds of the claims, or equivalences of such meets and bounds are therefore intended to be embraced by the appended claims.

Claims

1. In a nitrogen-controlled freezing type dehumidifying and drying apparatus capable of storing an agricultural and marine product in the interior of a drying chamber in which a freezer is installed, a nitrogen-controlled freezing type dehumidifying and drying apparatus, comprising: a drying chamber in which an air suction line and a nitrogen supply line of a nitrogen generator are connected for thereby receiving a nitrogen gas generated by a nitrogen generator and maintaining a nitrogen gas environment therein; an external air inlet pipe which is connected between a suction side automatic valve and a nitrogen supply unit installed in an air suction line which connects the drying chamber and the nitrogen generator for thereby sucking an external air and generating a nitrogen at the time when a nitrogen generator is initially operated for changing the interior of the drying chamber to a nitrogen gas environment; and an opening and closing valve which is installed in the external air inlet pipe for thereby controlling a suction and disconnecting operation of an external air.

2. The apparatus of claim 1 , wherein in the interior of the freezer installed in the interior of the drying chamber, a condensed water tank is installed in a discharging pipe of a condensed water collector for collecting a water condensed by a heat exchanging operation by an evaporator, and a water level sensor is installed in a condensed water tank in such a manner that the discharging operation of the condensed water is stopped at a position higher than a connection portion of a drain pipe by detecting the level of the condensed water when discharging the condensed water stored in the condensed water tank.

3. The apparatus of claim 2, wherein said water level sensor includes: a low water level detection rod for detecting a low water level in such a manner that the discharging operation of the condensed water is stopped at a low water level slightly higher than that of a connection portion of the drain pipe when discharging the condensed water stored in the condensed water tank; a high water level detection rod for detecting a high water level in such a manner that a condensed water is discharged when the condensed water stored in the condensed water tank reaches at a high level at which the condensed water is discharged; and a condensed water detection rod which is extended to a portion lower than the low water level detection rod for thereby detecting as to whether the condensed water is stored in the condensed water tank.