RU2306499C2 - Device for food product block freezing and thawing - Google Patents

Abstract

FIELD: stationary refrigeration devices, for instance cold rooms.

SUBSTANCE: food product block freezing and thawing device comprises insulated chamber. Installed in the chamber are air cooler, air heater, fan, air channel, product temperature sensors, air temperature sensor, microprocessor and cart. The cart is provided with metal shelves having ribs on inner surfaces and arranged inside rectangular box in horizontal positions. The rectangular box is provided with end sealing means and is supported by wheels. The carts may slide along guiding means having limiting posts from the first guiding means sides and with springing pressing members from the second sides thereof.

EFFECT: increased efficiency of food product treatment.

7 cl, 7 dwg

Description

The invention relates to refrigeration and technology, and in particular to devices for refrigeration processing molded in the form of blocks, packaged food products and can be used in meat, dairy, fish, fruit and vegetable and food industries.

A known method and device for thawing frozen packaged food in an air stream. The device contains a thermally insulated chamber with an air cooler, an air heater located in it, and there are also pallets for placing packaged products installed in series and forming a stack, blown by an air stream, the temperature of which is set by a programmable control device [1].

The disadvantage of this device is that the intensity of the defrosting process in it is limited by the fact that for defrosting, heated (or cooled) air circulating through the stack is used, which has a low coefficient of thermal conductivity and insufficient heat capacity for the defrosting process. In addition, this device does not change the composition of air and its humidity, creates a controlled atmosphere (RA) and bactericidal treatment of air.

There is also known a method of thawing meat products using electroconvection, which is carried out in a thermally insulated chamber at a constant temperature of the circulating ionized air stream created by the electrode attachment, which is the causative agent of the air stream. The air flow temperature is maintained by the integrated heating element [2].

The disadvantage of this method is that the defrosting process is carried out at a constant temperature plus 20 ° C, which leads to overheating of the product and a decrease in its quality.

A known apparatus for the refrigeration processing of packaged food in a stream of cold air.

This apparatus contains a heat-insulated chamber, a chain conveyor located in it with supporting C-shaped elements for placing the product with perforated shelves, air coolers, fans. Product placed on a perforated shelf of a bearing C-shaped element and periodically changing its support by turning over. the plane of contact with the perforated shelf is blown by a stream of cold air [3].

The disadvantage of this device is that it does not have high efficiency of refrigeration processing: freezing and thawing, due to the fact that the product is periodically outside the zone blown by a stream of cold air, and in addition, the surface of the supporting C-shaped element in contact with the product is made of perforated metal sheet and does not have a developed heat transfer surface. Another disadvantage of this device, which reduces the efficiency of refrigeration processing, is that it has a high aerodynamic drag, because the air flow passing through the container with the C-shaped elements carrying the product randomly located continuously changes the direction of travel and is turbulized, striking the conveyor parts and the C-shaped supporting elements.

The prior art apparatus for preserving food products (RU No. 2159399, F25D 13/00, 2000), adopted as the closest analogue and containing a thermally insulated chamber, air cooler, air heater, fan, duct.

A disadvantage of the known device is the low efficiency and quality of food processing.

The objective of the invention is to provide a device for the refrigeration processing of food products that allow efficient and high-quality processing of food products.

The technical result, which consists in increasing productivity and reducing energy consumption, as well as in reducing the level of bactericidal airborne contamination of the air and carrying out the process in a controlled atmosphere, is achieved by the fact that the device for freezing and thawing food products in blocks contains a thermally insulated chamber with an air cooler, an air heater, a fan in it , product temperature sensors and air temperature sensor, microprocessor, trolleys with metal shelves, finned lower and horizontal horizontally inside a rectangular box with end seals mounted on wheels, and guides, and the trolleys are mounted to move along the guides, which on one side are equipped with restrictive racks with sealing elements, and on the other hand, a spring clamping device. An apparatus for two-stage bactericidal treatment of air is fixed to the ceiling of the thermally insulated chamber on insulating pendants, so that the air stream emanating from the duct provides air movement inside the apparatus for two-stage bactericidal treatment of air, in which an electrode attachment is used to form an electroconvective and ionized air flow.

In addition, to remove air from the thermally insulated chamber, a check valve is installed in the upper part of the thermally insulated chamber, which passes only air from the thermally insulated chamber, while a blower is attached to the check valve to remove air through the air check valve, and, to compensate for the air removed from the thermally insulated chamber, for example, from a reservoir (Dewar vessel), liquid nitrogen or liquid carbon dioxide, moreover, the removal of air and the supply of liquid nitrogen or liquid carbon dioxide are balanced by to wham. The device is equipped with a steam generator to create optimal air humidity in a thermally insulated chamber.

Figure 1 shows a longitudinal section of the device, figure 2 shows the transport trolley and sealing units - (place 1 and 2) and section AA, figure 3 schematically shows an apparatus for bactericidal treatment of air, figure 4 shows a stand-alone functional module .

A device for freezing and thawing food products in blocks contains a thermally insulated chamber 1 with an air cooler 2 located therein, an air heater 3, a fan 4, sensors 4, 5 for controlling the air temperature and a sensor 7 for controlling the air temperature in the thermally insulated chamber 1, microprocessor 8, carts 9, containing metal shelves 10, ribbed from below, with the product unit 11 located on them. The metal shelves 10, finned below, the carts 9 are placed inside a rectangular box 12, on the opposite ends of which there are seals 13 and 14 of the protrusion-cavity type, and the box itself is mounted on the wheels 15. The cart 9 moves along the guides 16 laid on the floor of the thermally insulated chamber 1 , to the restrictive rack 17, which has seals (not shown in the drawing) with a diffuser 18 and a fan 4 fixed on it. Composition of trolleys 9 arranged sequentially on guides 16 and tightly joined by seals 13 and 14, p clamps to the restrictive post 17 spring clamping device 19.

To give the air stream a certain direction, an air duct 20 is provided, and in the zone of action of the air stream, an apparatus for bactericidal treatment of air 22 is fixed to the ceiling on electrically insulating suspensions 21, containing a zone B for pre-treating the air with zoneless lamps and a zone E for treating air with an electrode attachment. The device is enclosed in a protective casing 23.

The device is equipped for changing air humidity with a steam generator 24, a solenoid valve 25, a nozzle 26, for supplying steam with an air humidity sensor 27, and for creating a RA it is equipped with a check valve 28, a reservoir (Dewar vessel) 29, and for reserving liquid nitrogen or liquid carbon dioxide with a gas pipeline 30 , the solenoid valve 31, the nozzle 32 and the oxygen concentration sensor 33. The thermally insulated chamber 1 is closed by the door 34. To pump air through the check valve 28, a fan 35 is installed.

For refrigeration processing of food products in blocks, not all components of the device can be used, as described above, but only a stand-alone simplified functional module (see Fig. 4), containing guides 16, restrictive racks 17, a diffuser 18, a fan 4, an air duct 20 , the composition of the trolleys 9 and the spring clamping device 19. An autonomous functional module can be installed in the refrigerating chamber of a production refrigerator.

The device operates as follows:

To carry out the freezing process, the cooled product is packaged in bags of polymer film, and the bag is shaped as a parallelepiped - block 11, which is stacked on the metal shelf 10 of the trolley 9, which contains a rectangular box 12 with a seal 13 and a seal 14 along its perimeter at the ends, s placed in it below the metal shelves 10, arranged horizontally, and the box is mounted on wheels 15. The cart 9 through the door 34 along the guides 16 rolls into a thermally insulated chamber 1 and tanavlivaetsya so that the seal 13 of one truck docks with a sealant 14 to form another trolley tight connection. After sequential installation (docking) of several carts with the product, the formed cart (train) of carts is tightly pressed by the spring clamping device 19 to the restriction post 17. The fan 4 is turned on, and air begins to circulate through the voids inside the docked carts with the product and enters cooling air cooler 2, then it passes through the switched off air heater 3 and is discharged through the air duct 20 into the volume of the thermally insulated chamber 1.

To create a controlled atmosphere (RA) in the chamber, air is drawn in from the thermally insulated chamber 1 by a fan 35 and passed through a non-return valve 28. At the same time, liquid nitrogen or liquid carbon dioxide is sprayed into the chamber from the tank (Dewar vessel) 29 through a gas pipe 30 and a solenoid valve 31. 32.

For bactericidal treatment of air circulating in a thermally insulated chamber 1 as a coolant and in contact with the product, an apparatus for bactericidal treatment of air 22 is used.

The temperature of the air in the thermally insulated chamber, the course of the process of freezing the product blocks and the moment of the end of the process are controlled using two temperature sensors 5 and 6 located in the geometric center of the product blocks at the entrance to and from the carts (figure 2) and the temperature control sensor air 7 in the thermally insulated chamber 1, connected to the microprocessor 8. Upon reaching the set temperature in the freezing unit, the fan 4 is turned off by the command of the microprocessor 8 - the freezing process is completed. At the same time, the spring clamping device 19 is turned off, and the trolley 9 with the frozen product is rolled out of the thermally insulated chamber 1, and the product is sent for refrigerated storage.

The process of defrosting frozen product blocks takes place in the same sequence as the freezing process.

Blocks of the frozen product 11 are stacked on the bottom metal shelf 10 of the trolley 9. The trolleys 9, through the door 34 along the guides 16, are rolled into a thermally insulated chamber 1, hermetically joined together, forming a train (train). Unlike freezing, where only air cooler 2 is involved, when defrosting, both air cooler 2 and air heater 3 are used, so that their interconnected operation, controlled by microprocessor 8, provides a smooth decrease in air temperature in a given range of positive temperatures (see example No. 5).

For bactericidal treatment of air inside the thermally insulated chamber 1, an apparatus for two-stage bactericidal treatment of air 22 is used, consisting of the first along the zone B (Fig. 3) of preliminary air disinfection with bactericidal zoneless lamps and the second along the zone E for air treatment using an electrode attachment that creates electroconvective ionized air flow, which, in addition, provides air circulation through zone B of the apparatus for two-stage bactericidal treatment of air 22, replacing, essentially this fan, which is usually used in such designs. The apparatus for two-stage bactericidal treatment of air 22, enclosed in a protective casing 23, is attached to the ceiling of the thermally insulated chamber 1 on electrically insulating suspensions 21, so that it is in the zone of action of the air stream coming from the duct 20, while the jet contributes, along with the electrode attachment, the movement of air inside the apparatus for two-stage bactericidal treatment of air 22. If necessary, maintain in a thermally insulated chamber 1 during defrosting of the atmosphere with increased relative humidity Stu air from the steam generator 24 through the solenoid valve 25 and nozzle 26 is supplied steam. The required relative humidity is controlled in accordance with a given program by a humidity sensor 27 connected to the microprocessor 8.

The completion of the defrosting process is controlled by two temperature sensors 5 and 6 connected to the microprocessor 8. The thawed product removed from the thermally insulated chamber 1 is sent for industrial processing.

For freezing and thawing food products in blocks, a stand-alone simplified functional module is used (Fig. 4), which forms an independent device located in the refrigerating chamber of a production refrigerator.

The module is placed in a conventional refrigerating chamber - a warehouse in which it is possible to maintain the air temperature in the range from minus 30 ° С to plus 20 ° С. The product in the blocks is placed on the metal shelves of the bottom 10 trolleys 9, which are inserted along the guides 16 into the refrigerating chamber-warehouse, and is installed so that the trolleys 9 are hermetically connected to each other, forming a train (train), tightly compressed by a spring clamping device 19.

The fan 4 is turned on, and the air from the storage chamber, heated during defrosting and having a positive temperature or cooled during freezing and having a negative temperature, blows the product blocks 11 in the carts 9, respectively defrosting or freezing them.

The process is controlled by temperature control sensors of the product 5 and 6, introduced into the product blocks and connected to the microprocessor 8 (see figure 2).

EXAMPLES

Example 1

Cottage cheese cooled to a temperature of plus 2 to plus 6 ° C, placed in a bag of packaging material and molded in the form of a parallelepiped - block 11 with a thickness of 50-75 mm and weighing up to twelve kilograms, is placed on the upper smooth surface of the metal shelf of the trolley 9, ribbed from the bottom 10 ( see FIG. 2), which is placed in a thermally insulated chamber 1 for freezing. During freezing, the product block is blown by a stream of cold air with a temperature from minus 25 to minus 35 ° C, and the air speed at the surface of the block and under the finned shelf ranges from 3 to 5 m / s. The freezing process stops when the temperature in the geometric center of the block reaches minus 18 - minus 20 ° C.

Example 2

A frozen cottage cheese block having a volume average temperature of minus 20 ° С is placed in a package on a metal shelf ribbed from below 10, carts 9 and blown with air, the speed of which can vary from 2 to 5 m / s, and relative humidity varies in the range of 50- 95% Air temperature decreases stepwise: at certain time intervals

a) in increments of plus 5 ° C from 20 ° C to 5 ° C (20 ° C, 15 ° C, 10 ° C, 5 ° C)

b) in increments of plus 5 ° C from 15 ° C to 5 ° C (15 ° C, 10 ° C, 5 ° C)

c) in increments of + 3 ° C from 12 ° C to 3 ° C (12 ° C, 9 ° C, 6 ° C, 3 ° C)

The defrosting process is set by the optimal program for this type of cottage cheese and is controlled by microprocessor 8.

Example 3

The frozen product block, for example, minced meat, is freed from the packaging material before being thawed and placed on a metal shelf ribbed from below 10, carts 9 and blown with air, the air passing through the apparatus for two-stage bactericidal treatment of air 22 to reduce the level of bactericidal air contamination. Air velocity and temperature are maintained as noted in example 2, and relative humidity is maintained in the range of 55-65%.

Example 4

The frozen block of product 11 is freed from packaging material and placed on a metal shelf ribbed from below 10, trolleys 9, the trolley is installed in a thermally insulated chamber 1, where the product is thawed in a controlled atmosphere (RA) stream. For this, the thermally insulated chamber 1 from the reservoir (Dewar vessel) 29 is fed through a gas pipeline 30 with a solenoid valve 31 and a nozzle 32 with liquid nitrogen or liquid carbon dioxide. At the same time, the fan 35 removes air through the check valve 28 from the thermally insulated chamber 1. The oxygen concentration in RA decreases to 2% and is monitored by a concentration sensor 33, and the concentration of CO ₂ rises to 14-20%. Upon reaching a predetermined reduced oxygen concentration in the RA, at the command of microprocessor 8, the supply of inert gases (liquid nitrogen or liquid carbon dioxide) to the thermally insulated chamber 1 is stopped and the air flow through the check valve 28 is simultaneously stopped. The optimal oxygen content in RA is 1% -2.5% and the content of CO ₂ is 15%. The supply of liquid nitrogen having a temperature of minus 196 ° C also contributes to a gradual stepwise decrease in the temperature of RA.

Example 5. An autonomous functional module is installed for freezing in a freezer of a production refrigerator. Trolleys 9 are rolled along guides 16 with the product chilled from plus 2 to plus 6 ° С in blocks 11, for example, with cottage cheese, the composition is formed, carts 9 are hermetically joined by seals 13 and 14 (see Example No. 1). The air temperature in the chamber is lowered to minus 25-35 ° C using standard air coolers, fan 4 is turned on, and the product is frozen. The progress of the freezing process is monitored using product temperature sensors 5 and 6.

When defrosting, frozen product blocks with a volumetric average temperature in the center of the block minus 20 ° С are loaded onto trolleys into the chamber of the industrial refrigerator. The air temperature in the production refrigerator before defrosting is from plus 12 to plus 20 ° C. It is advisable to gradually, stepwise decrease in air temperature from relatively high from plus 18 to plus 20 ° C at the beginning of the defrosting process to low from plus 2 to plus 6 ° C at the end. The air temperature should be determined depending on the temperature field inside the defrosted object - the product unit and on the surface of the product unit.

Information sources

1. Patent RCT / DK 90/00229, priority 07.09.1989, A 23 L 3/365.

2. RF application No. 2002115074/13, 06/07/2002, A 23 B 4/07.

3. RF patent No. 1595146, priority 03.15.1989, F 25 D 13/06. Application 4663640 / 40-13, 03/15/1989.

Claims (7)

1. A device for freezing and thawing food products in blocks, containing a thermally insulated chamber with an air cooler, an air heater, a fan, an air duct, product temperature sensors and an air temperature sensor, a microprocessor, trolleys with metal shelves, ribbed below, and located horizontally inside a rectangular boxes with mechanical seals mounted on wheels, and guides, with trolleys mounted for movement along the guide which are provided on one side with restrictive posts with sealing elements, and on the other hand are equipped with a spring clamping device. 2. The device according to claim 1, in which the apparatus for two-stage bactericidal treatment of air is mounted on the ceiling of the thermally insulated chamber on electrically insulating suspensions in such a way that the air stream emanating from the duct allows air to move inside the apparatus. 3. The device according to claim 2, in which the apparatus for two-stage bactericidal treatment of air using an electrode attachment for the formation of electroconvection ionized air flow. 4. The device according to claim 1, in which to remove air from a thermally insulated chamber in its upper part, a check valve is installed that lets air out of the thermally insulated chamber to the outside. 5. The device according to claim 4, in which the check valve is connected to the fan to remove air through the check valve and lower the oxygen content in the controlled atmosphere of the thermally insulated chamber. 6. The device according to claim 4, in which to compensate for the air removed from the thermally insulated chamber, liquid nitrogen or liquid carbon dioxide is supplied into it, the air removal and the supply of nitrogen and carbon dioxide being volume balanced. 7. The device according to claim 1, which is equipped with a steam generator to create optimal air humidity in a thermally insulated chamber.

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