NEW DESIGN FOR AN HYGIENIC WIDE ANGLE LIQUID NITROGEN SPRAY NOZZLE
Publication Date: 2015-Jun-05
The IP.com Prior Art Database
In the food industry, the hygienic design of equipments becomes critical. The food processors are more and more focused on the hygienic design of the food processing machines and especially the part of the machines which are in contact or close to the food product.
As an example, in most food cryogenic freezers, a key part of the machine is the nitrogen injection system, the place where the liquid nitrogen is sprayed into the cold zone and sometime on the product. This nitrogen injection system is made of spray nozzles. It is often installed very close to the product being frozen. The nitrogen which goes through the spray nozzle goes in direct contact with the food product. As a result, the spray nozzles are key parts in terms of hygiene. Contaminated nozzles or difficult to clean nozzles result in contaminated product.
That’s why the cryogenic spray nozzles should be manufactured with the highest hygienic design.
In a cryogenic linear tunnel freezer, the spray nozzles are installed in the cold zone, all over the width of the conveyor belt, just above the belt and over the products being conveyed. In terms of process, the spray nozzles shall spray the liquid nitrogen all over the belt and they shall “spray cold” in a consistent way all over the width of the belt. If the system doesn’t spray enough nitrogen on the right side of the belt, the products on the right side will be to warm and they will be rejected.
That’s why a very common device to achieve this is to use flat spray pattern nozzles. These nozzles spray the liquid nitrogen on a defined width of the belt. The nozzles are evenly installed on a spray bar with the same distance between each of them to achieve a “spray of cold” (consistent volume of liquid nitrogen sprayed) over the width of the belt.
On the market, we can find the following spray bars:
- Standard screwed brass spray nozzles screwed on a stainless steel pipe: the material and the thread of these nozzles is clearly a weak point in terms of hygiene. Brass can oxidize and produce non food grade material (brass oxide). The thread can harbor microbes.
- Standard screwed stainless steel spray nozzles screwed on a stainless steel pipe: the thread of these nozzles is clearly a weak point in terms of hygiene. The thread can harbor microbes.
- Fully welded stainless steel spray nozzle: This design is good in terms of hygiene but the cost of such equipment is high.
The nozzles can be direct spray nozzles or mirror type spray nozzles. The material of construction of the spray nozzle can be brass or stainless steel.
We then propose below a new design for creating flat spray patterns.
Two main methods are used to create flat sprays from a single orifice:-
1. The orifice is shaped as a slot, or as an elliptical outlet usually with a “V” shaped cut-out to control the shape of those spray.
2. A jet of liquid from a circular orifice can impinge upon an...