JPS5818579B2 - lentils - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for rapidly freezing foods and the like using an inert low-temperature liquefied gas such as liquid nitrogen.

Generally speaking, this type of device transports food or other frozen items onto a belt conveyor 2 flowing through an insulated tunnel 1 using an inert low-temperature liquefied gas as shown in FIGS. 1 and 2. For example, freezing objects are rapidly frozen by spraying liquid nitrogen or the like, or by immersing the freezing objects in liquid nitrogen, and have been put into practical use for a long time.

In this case, the evaporated gas of liquid nitrogen is effectively used as a pre-cooling gas, but the pre-cooling means in conventional devices are usually a method using a stirring fan 3 as shown in FIG. 1 and a method using a circulation method as shown in FIG. 2.

That is, in the method shown in Fig. 1, food is frozen by spraying liquid nitrogen from a spray device 4 installed downward on the ceiling of the freezing section of an insulated tunnel, and the low-temperature nitrogen gas generated at this time is applied to the pre-cooling section. The temperature of the food is lowered, and the mechanism of this pre-cooling section is that a fan attached downward to the ceiling of the insulated tunnel stirs low-temperature gas, creating a downward airflow to cool the food.

In this method, there is a limit to the area that can be uniformly stirred by one fan, so it is not rational to install many fans in a large freezer.

Next, the circulation method as shown in FIG. 2 is a method in which one or more blowers 5 are used to circulate gas in the advancing direction of the conveyor or in the opposite direction.

In this method as well, since the diameter of the outlet of the blower 5 is extremely small compared to the cross-sectional area of the heat-insulating tunnel, it is difficult to flow the low-temperature gas into the tunnel at a uniform flow rate with respect to the cross-sectional area.

If the gas flow velocity in the tunnel is uneven in this way, there is a drawback that food cannot be frozen uniformly.

The present invention improves these drawbacks of the conventional methods, and enables the precooling low-temperature gas to circulate uniformly and to be uniformly supplied over the entire surface of the conveyor.

The present invention will be explained in detail below with reference to FIGS. 3 and 4.

In Figures 3 and 4, 1 is an insulated tunnel, 2 is a conveyor for transporting frozen objects, 4 is a liquid nitrogen spray device, and 6
is a B cold air duct, 7 is a cooling circulation blower, 18 is a cold air injection box equipped with many cold air injection nozzles, 9 is a cold air injection nozzle for injecting cold air vertically to the conveyor, and 10 is a cooling air injection box for injecting cold air perpendicularly to the conveyor. baffle plate for flushing, 11
is a discharge duct, and 12 is a filter.

The supplied liquid nitrogen is sprayed by the spray device 4,
It touches the frozen object on the conveyor, gasifies it, and flows inside the insulation tunnel 1 toward the discharge duct 11.

The low-temperature liquefied gas gasified in the precooling section before reaching the discharge duct 11 is transferred to the cold air duct 6 and the cooling circulation blower of the present invention.
7. Pre-cool the food on the conveyor by circulating it through a circulation unit consisting of a cold air injection box 8.

That is, low-temperature nitrogen gas passes through a filter 12 and a duct 6, is sucked in by a blower 7, is discharged into an injection box 8, and is conveyed vertically and uniformly over the entire surface from numerous injection nozzles 9 formed at the bottom of the injection box. Cool the food by spraying it onto the food above.

The gas that has exchanged heat with the frozen product passes vertically through a conveyor 2 formed of a net, and then passes through the filter 12 again.
It is circulated from the duct 6 to the blower 7.

The low-temperature nitrogen gas repeats this circulation and gradually approaches the discharge duct 11. By installing a plurality of the above-mentioned circulation units, the low-temperature nitrogen gas cycles through each circulation unit as it approaches the discharge duct 11 from the spray device 4. Since the temperature of the gas gradually increases, the internal temperature of the precooling group as a whole forms a smooth temperature gradient.

The apparatus according to the present invention is constructed as described above, and as a result, the following features and effects can be obtained.

That is, since the low temperature gas is uniformly injected over the entire surface of the conveyor, it has become possible to uniformly freeze the objects to be frozen on the conveyor.

(11) Since the cycle of low-temperature liquefied gas is completed, the efficiency of utilizing cold is extremely high.

(It has become possible to improve the performance of the blower, such as the wind volume and wind pressure, to promote heat exchange between the low-temperature gas injected from the nozzle and the frozen product.

This makes it possible to shorten the length of the pre-cooling section, thereby reducing the length of the entire device.

(V) Furthermore, even if the ejection speed of the cold gas is increased as described above, the cold gas flows from the top to the bottom of the frozen items, so the frozen items are not blown away by the cold air.

(g) Furthermore, by forming the circulation unit as described above, it has become possible to manufacture a freezing device in which the width of the conveyor 1- is increased.

As described above, the quick freezing device according to the present invention has significantly improved performance and efficiency compared to conventional devices.

[Brief explanation of the drawing]

i Figures 1 and 2 are fIL of a conventionally used continuous quick freezing device. Figure 3 is a cross-sectional view of an embodiment of a continuous quick freezing device according to the present invention. FIG. 5 is an enlarged view of section B in FIG. 4. 1 is an insulated tunnel, 2 is a conveyor, 6 is a cold air duct,
7 is a cooling circulation blower, 18 is a cold air injection box, and 9 is a cold air injection nozzle.

Claims (1)

[Claims] 1. In an apparatus for rapidly freezing objects to be frozen by spraying low-temperature liquefied gas such as liquid nitrogen, which are transported by a belt conveyor in an insulated tunnel, the belt conveyor A cold air circulation mechanism includes a cold air duct and a blower connected to the cold air duct in a direction substantially perpendicular to the flow direction of the air, and sucks evaporated cold air and discharges it; A plurality of cold air circulation injection units each comprising a cold air injection mechanism that injects cold air almost vertically and uniformly over the entire surface onto the conveyor through a cold air injection box having a large number of injection nozzles is provided. Continuous quick freezing equipment.