RU2278336C2 - Air tunnel quick freezing apparatus - Google Patents

Abstract

FIELD: the invention refers to refrigerator technological equipment for freezing food products at their contact with low temperature air.

SUBSTANCE: the apparatus provides rational distribution of air for creation symmetrical conditions for freezing, reducing durability of the process of freezing, reducing capital expenditures, and also for conservation quality of food products. The apparatus has a heat insulating chamber with transporting member element for freezing products and air distributing arrangement , fulfilled in the shape of two air conduits of box shape , mounted parallel along both sides of the transporting member element and converging in the direction of the product, joined between themselves with a bent dipole collector, connected to the main pipeline. Each air conduit has a located longitudinally in its volume a rod with pivotally fixed transversal plates of bended form for passage of cooled air out of the refrigerating apparatus.

EFFECT: due to minimal distance between the ceiling of the chamber and the upper branch of the transporting member element making up from 100 till 110 mm, and also due to transversal forced air cooling of the product on the transporting element, duration of the process of freezing reduces 30-35%, at that drying loss is excluded.

2 cl, 6 dwg

Description

The invention relates to refrigeration processing equipment, namely, freezers for freezing food products in contact with low-temperature air.

Known tunnel freezing apparatus with the possibility of alternately using liquid nitrogen, gaseous nitrogen and low-temperature air as a refrigerant, consisting of a heat-insulated casing, the working volume of which is divided into three freezing zones, where axial fans are installed in the first and third zones, and a distribution manifold for the supply of liquid or gaseous nitrogen, as well as in the end walls there are channels for the input and output of cold air. A transporting body is placed along the entire length of the casing, and a ventilation device is mounted on the end side of the casing on the product inlet side to exhaust exhaust refrigerant vapors [RU, patent 2168123, cl. F 25 D 13/00, 2000].

The disadvantages of the device include the fact that fans are used to circulate the refrigerant in the casing of the device, which complicates the design and increases the power consumption of the installation.

Known tunnel freezing apparatus using low-temperature air (-60 ...- 120 ° C) from a turbo refrigerator and three ways of supplying it: through a distribution manifold located in the second zone of a three-zone device, through ducts mounted in the housing from the loading side and unloading the product, and using an inclined lattice screen (f. "Refrigeration", 2004, No. 9, p.2-7).

The proposed methods of air supply in the tunnel apparatus have several disadvantages:

- a method with a distribution manifold involves the use, without significant changes, of the design of the nitrogen tunnel apparatus and the three-zone principle. In this case, the product is not washed uniformly by the cooling medium, and it is also necessary to have circulation fans that significantly load the tunnel structure and increase the energy consumption of the installation;

- when using special channels - air ducts mounted in the heat-insulating enclosure of the case from the end sides of the device, there is no exhaust duct for exhausting refrigerant, however, additional side fans are required, which also leads to an increase in energy consumption. In addition, the manufacture of such channels in a thermally insulated housing leads to a decrease in the thickness of the insulation and is time-consuming.

Closest to the proposed and selected as a prototype is a tunnel-type apparatus using a method of supplying low-temperature air through an inclined grating screen (RU, patent 2231721, class F 25 D 13/06, 2004).

Despite the fact that the use of an inclined screen in the tunnel apparatus allows to exclude fans, stagnant zones can form in the area above the screen, where cold air will accumulate, form frost deposits, etc. In addition, the design of the screen allows for uniformity only with longitudinal blowing the product, i.e. part of the product when it is transported on the conveyor will already be frozen, and the final part is only chilled, which can lead to a deterioration in the quality characteristics of the product during its further storage.

Also, it should be noted that in the above methods of supplying low-temperature air to the tunnel apparatus it is rather difficult at the design level to ensure complete exhaustion from the exhaust vapor apparatus, since there are opportunities for leaks into the atmosphere.

The proposed invention is aimed at solving a technical problem, which is to ensure rational air distribution in the apparatus for creating symmetrical conditions of freezing, reducing the duration of the process, capital and energy costs, as well as maintaining the quality of food products.

The use in the tunnel apparatus of a special air distribution device with air ducts located along the conveyor will ensure uniform horizontal cross-sectional blowing of the product throughout the entire refrigeration process, thereby reducing the process time and ensuring high quality indicators of the finished product, as well as by reducing the distance from transporting body to the ceiling, reduce capital and operating costs.

The technical result, which consists in eliminating these shortcomings in a freezer, containing a thermally insulated chamber for freezing products with a conveying body and an air distribution device connected to a turbofan unit for supplying low temperature air, is achieved due to the fact that the air distribution device is made in the form of two box-shaped ducts, mounted parallel on both sides of the transporting body and tapering in the direction the movement of the product, interconnected by a U-shaped collector connected to the main pipeline, while each of the ducts has a rod located longitudinally in its volume with curved transverse plates mounted on it pivotally to ensure a change in their position in the horizontal plane with the passage of cooling air, and the transporting body has a length exceeding the length of the chamber for the formation of platforms for loading and unloading the product.

In addition, the apparatus has supports that contain removable wheels for moving the apparatus during the non-operational period, as well as the distance from the upper branch of the conveying organ to the chamber ceiling, which is 100 to 110 mm, necessary and sufficient to freeze a wide range of piece food products.

Figure 1 schematically shows a quick-freezing tunnel apparatus, a longitudinal section; the cross section of the apparatus (AA); view from the side of the product loading (View B); view from the unloading side of the product (View C); figure 2 shows a design diagram of an air distribution device; figure 3 shows a segment of the duct with curved guides.

The proposed apparatus consists of a thermally insulated housing 1, the working volume of which forms a chamber for freezing products. A transporting body 2 is placed along the entire length of the housing 1. The housing 1 of the apparatus contains an air distribution device 3, consisting of a main pipeline 4, a U-shaped collector 5 and two box-shaped ducts 6 with a rectangular section tapering in the direction of movement of the product, arranged in parallel along the transporting body 2 on both sides, with each of the air ducts 6 having a rod 8 arranged longitudinally in its volume with curved transverse plates 7 mounted pivotally thereon to ensure a change in their position in the horizontal plane with the passage of cooling air. The apparatus has a drive part 9 for the transporting body and a drive part 10 for lifting the heat-insulated body 1. In this case, the transporting body 2 has a length exceeding the length of the chamber 1 for the formation of loading platforms 11 and unloading 12 of the product. The apparatus has supports 13, containing removable wheels 14 for the convenience of moving the apparatus in a non-operational period. The unloading platform 12 contains a knife 15 for removing products from the transporting body 2. On the unloading side of the product 12, a device 16 for exhaust air removal is mounted with a view to its further use for technological needs.

Below are the technical characteristics of the air distribution devices of three modifications:

Air distribution marking Duct length L _BB , mm The distance between the ducts on the air supply side (conveyor width) V _K , mm The total width of the air distribution device V _BB , mm Minimum height of the main part Nvv min, mm BP 4 4000 500 700 320 BP 6 6000 750 950 320 BP 10 10,000 1000 1200 320

The device operates as follows. The product to be frozen is placed on the loading platform 11 of the transporting body 2, with the help of the drive part 9, the product is moved on the transporting body. From a turbo-refrigerating unit (not shown), air with a temperature of from -120 to -100 ° C is supplied through a U-shaped branch 5 to the air ducts 6 of the air distribution device 3. The air passes through the narrowing air ducts 6 and, using curved plates 7, changes its direction and transversely fed to the product, washing it, respectively, from two sides on the transporting body 2, providing symmetrical freezing. If necessary, it is possible to change the direction of the air flows in the horizontal plane by moving the rod 8 and changing the position of the hinged plates 7. The surface of the product freezes due to the instantaneous exposure to low temperature, practically eliminating the effect of drying, and the duration of the product cooling stage is significantly reduced. With further movement of air through the duct 6, its speed decreases slightly and the temperature changes to -80 ...- 60 ° C, and with an identical effect on the product, its final freezing and temperature equalization throughout the volume is ensured. Exhaust air vapors having a sufficiently low temperature are sucked out of the apparatus body 1 through an exhaust air exhaust device 16 and can be sent to cooling chambers for technological needs (storage, pre-cooling). The frozen product exits the apparatus through the unloading platform 12 and is bookmarked for storage.

The design of the proposed device is simple to manufacture and less energy-consuming, and the device operates using cold air - environmentally friendly refrigerant. The reduction in the distance between the ceiling of the chamber and the upper branch of the transporting body, as well as the symmetrical conditions of freezing the product due to transverse blowing throughout the entire movement on the transporting body, achieved in the proposed design reduce the duration of the process by 30 ... 35%, while eliminating product weight loss from drying out.

Claims (3)

1. An air tunnel freezing apparatus containing a thermally insulated chamber for freezing products with a conveying body and an air distribution device connected to a turbofan unit for supplying low temperature air, characterized in that the air distribution device is made in the form of two box-shaped ducts mounted parallel on both sides of the conveying body and tapering in the direction of product movement, interconnected by a U-shaped a lecturer connected to the main pipeline, wherein each of the ducts has a rod arranged longitudinally in its volume with curved transverse plates mounted pivotally thereon to provide a change in their position in the horizontal plane with the passage of cooling air, and the transporting body has a length exceeding the length of the chamber for the formation of platforms for loading and unloading the product. 2. The apparatus according to claim 1, characterized in that it has supports that contain removable wheels for moving the apparatus in a non-operational period. 3. The apparatus according to claim 1, characterized in that the necessary and sufficient for freezing a wide range of piece food products, the distance from the upper branch of the conveying body to the ceiling of the chamber is from 100 to 110 mm.

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