Cryogenic cooling method and device for products in a tunnel

Abstract

A tunnel-type cooling device for products, particularly food products, comprising: an insulated enclosure with an inlet and an outlet; means for conveying products between the inlet and the outlet; means for supplying a cryogenic liquid into the enclosure to allow the products to come into contact with this liquid, supplying means including one or more spray rails for the liquid on the products; and ventilation means, capable of blowing cold gas onto the passing products, characterized in that said means for supplying cryogenic liquid include means for spraying the cryogenic liquid towards the underside of the products.

Description

Title of the invention: Method and device for cryogenic cooling of products in a tunnel

[0001] The present invention relates to the field of food product cooling processes in tunnel-type devices, implementing direct injections of a cryogenic fluid such as liquid nitrogen.

[0002] Traditionally, such tunnels include: - an isolated enclosure equipped with an entrance and an exit; - means of conveying products to be frozen or chilled, between the entrance and the exit; - means of bringing a cryogenic liquid into the enclosure to allow the products to come into contact with this liquid (most commonly, these means of bringing the liquid into contact with the products, spraying ramps located most often in the tunnel area near the exit); - and ventilation means, capable of blowing cold gas onto the products passing by, these ventilation means are generally located in the tunnel area near the entrance (in these traditional tunnels, the principle of the counter-current exchanger is often used and thus the spraying is positioned in the exit area of ​​the tunnel while the ventilation is often positioned in the area rather close to the entrance). - in such known tunnels, the liquid pressure that feeds the spray booms is in a range traditionally from 0.5 to 3 bar.

[0003] Most commonly, the majority of cryogenic tunnels and mechanical cold tunnels carry out heat transfers on the top of the products, they focus the transfers on only one part of the product, the top.

[0004] Cryogenic equipment therefore combines on the top of the product the intervention of two types of transfer: spraying and convection.

[0005] The present invention aims to propose a solution for improving heat transfers in such cryogenic tunnels, particularly the transfer of cold from below the product.

[0006] In the context of the present invention, we are particularly interested in products called "paste products", such as pizzas, quiches, flammekueches, tarts, and other croque-monsieur.

[0007] These products have in common a paste base in the lower part which requires more energy (frigories) than the upper part to reach the desired freezing / deep-freezing temperature.

[0008] For decades, the food industry has used mechanical refrigeration to freeze these dough-based products, but in recent years, a new technology has emerged on the market: cryogenic tunnels for freezing pizzas, quiches, and flammekueche. This equipment offers numerous advantages over traditional freezing methods and is profoundly transforming the industry by reducing electricity consumption, investment, and floor space.

[0009] This cryogenic technology allows products to be frozen faster than with traditional freezers. Cryogenic tunnels use supercooling gases (liquid nitrogen and liquid CO2) to lower the temperature of products much more rapidly. Food can be frozen in less time, which is a considerable advantage for companies that have to manage a large volume of frozen goods.

[0010] Furthermore, cryogenic tunnels allow for more uniform and efficient freezing. The speed of freezing minimizes damage caused by ice crystals, meaning that frozen products have a texture closer to that of fresh products, with better preservation of their taste and texture. This can significantly improve the quality of frozen products, which can attract new customers and retain existing ones.

[0011] Finally, next-generation cryogenic tunnels can be more economical in the long run than traditional freezers. The supercooling gases used in cryogenic tunnels are more efficient than the cooling systems used in traditional freezers, which means that energy costs are reduced. In addition, the speed of freezing saves time, which can lead to increased productivity and reduced labor costs.

[0012] According to the present invention, a solution is then proposed that can freeze from above and below by utilizing thermal transfers by spraying from below and convective transfers from above.

[0013] Cryogenic tunnel freezing from above and below is an innovation that is transforming the food industry. With its advantages in terms of speed, quality, and economic efficiency, this new generation of cryogenic tunnels for freezing products is becoming a smart choice for companies that want to stand out and offer superior quality frozen products to their customers.

[0014] The present invention then relates to a product cooling device, including food-grade tunnel-type tunnels, comprising: - an isolated enclosure equipped with an entrance and an exit; - means of conveying products between the entry and exit points; - means of bringing a cryogenic liquid into the enclosure to allow the products to come into contact with this liquid, means of bringing in including one or more spray rails for the liquid onto the products; - and ventilation systems capable of blowing cold gas onto the products scrolling,

[0015] characterized in that said cryogenic liquid delivery means include means for spraying the cryogenic liquid towards the underside of the products.

[0016] According to one embodiment of the invention, depending on each configuration, dimensions of the tunnel and products to be treated, a determined number of cryogenic liquid projection nozzles will be positioned above the conveyor and therefore above the products being passed, and a determined number of cryogenic liquid projection nozzles will be positioned below the conveyor and therefore below the products being passed.

[0017] According to one of the embodiments of the invention, to treat food products having a difference in composition between the top and the bottom, the distribution of the cryogen projection nozzles will be adapted accordingly: for example for pizzas and flammekueches a distribution of nozzles comprising preferably one % of the nozzles implemented on the top of the products and ¾ of the nozzles implemented below the products.

[0018] This distribution helps to limit the temperature differences between the top and bottom of the product, as demonstrated by the experiments carried out by the Applicant.

[0019] The residence time of the product is reduced, which makes it possible either to increase the rate or to reduce the regulation temperature of the tunnel.

Claims

Claims

1. Device for cooling products, in particular food products, of tunnel type, comprising: - an insulated enclosure with an inlet and an outlet; - means of conveying products between the entrance and the exit ; - means for supplying a cryogenic liquid inside the enclosure to allow the products to come into contact with this liquid, supply means comprising one or more ramps for projecting the liquid onto the products; - - and ventilation means, capable of blowing cold gas onto the products parading, where said means for supplying cryogenic liquid comprise means for spraying the cryogenic liquid towards the top of the products and means for spraying the cryogenic liquid towards the bottom of the products, characterized in that a quarter of the nozzles are implemented on the top of the products and three quarters of the nozzles are implemented below the products.

2. Device according to one of the preceding claims capable of receiving products to be treated which are so-called “dough” products such as pizzas, quiches, flammekueches, tarts, and other croque-monsieurs.