Abstract:
A food freezer having a thermally insulated enclosure wherein an endless conveyor having a lower loading section, a main helical section and an uppermost unloading section is primarily driven by engagement between its inner edge and the sidewall of a rotatable center cage, which includes a plurality of uniformly spaced apart vertical bars. The lower end of the center cage can be blocked, and a centrifugal blower is axially located at the upper end of the cage to suck gas from the interior of the cage and discharge it horizontally outward along the undersurface of the top wall so that it flows outward, then downward and, finally, radially inward in an overall generally toroidal pattern through the tiers of the helical belt section where it withdraws heat from the freezes the food products being carried therealong. Various arrangements, e.g., adjustable restrictors, are illustrated for creating vertical gradients in the radial inflow of gas through the helical section so that the cold gas flows inward at a greater rate in lower regions of the helical section than in the upper region. Cryogen injection devices for spraying a cryogen, such as liquid CO.sub.2 or liquid N.sub.2, radially inward to impinge upon the food products on the belt, may be located at selected positions about the perimeter and at various vertical levels. Radial inflow of gas adds to the effectiveness of the impinging spray against the food products; however, the overall freezer construction is also advantageously employed with mechanical cooling of the gaseous atmosphere via one or more heat exchange coils.
Abstract:
A food freezer having a thermally insulated enclosure and an endless conveyor having a loading section, a food freezing section and an unloading section. Blowers circulate gas throughout the interior of the enclosure, and devices for injecting liquid CO.sub.2 to preferably cause CO.sub.2 snow particles to impinge upon the food products on the belt are located at selected positions about the belt and may be at various vertical levels, some of which are preferably at least slightly above the belt. By piping the liquid CO.sub.2 so that it flows only upward and/or horizontally toward the spray nozzles within the thermally insulated enclosure, any solid CO.sub.2 that may accumulate adjacent the upstream side of the spray nozzle orifices is melted by CO.sub.2 vapor which gravitates upward in the vertical piping.
Abstract:
Disclosed are methods and apparatus for forming frozen food products, especially frozen foamed food products wherein the products contain bubbles having a reduced average size preferably in a narrow size range or contain ice crystals having reduced size.
Abstract:
A tunnel freezer uses carbon dioxide snow to directly contact product carried on a conveyor belt passing through the freezer. Fans are provided above and below the upper conveyor belt run carrying the product, with the fans above and below having downwardly directed exhaust. Trough-shaped deflector plates are provided adjacent the lower fans to circulate a flow adjacent the underneath surface of the upper conveyor belt run. Preferably, circulation adjacent the upper conveyor belt run is generally parallel to the upper conveyor belt run, and turning vanes are provided to deflect the flow upwardly through the upper conveyor belt run. Freezers may be provided with one or more cooling zones arranged in series along the path of conveyor belt travel.
Abstract:
Combined cryogenic and mechanical refrigeration freezer utilizing an open spiral conveyor for transporting food to be frozen through a first cryogenic zone enclosed by a secondary housing and then through a mechanically refrigerated zone subjected to circulating air cooled by mechanical refrigeration and cryogenic vapor from the first cryogenic zone.
Abstract:
A food freezer having a mechanical refrigeration system comprising first and second closed-loop fluid circuits, wherein the first fluid circuit employs carbon dioxide as its refrigerant and transfers heat to the second fluid circuit, which in turn transfers heat to the environment or to another fluid circuit. In the first fluid circuit evaporator, carbon dioxide is maintained at pressures between 60.4 psig and 120 psig. In a preferred embodiment of the invention, the freezer employs at least two separate blowers or fans for circulation of air or other gas in the freezer enclosure. One blower/fan operates continuously to maintain circulation of cold air or gas in the freezer. The other blower/fan operates intermittently or at variable speeds to vary air flow across the evaporator, and thereby increase or decrease heat transfer from the freezer interior to the first fluid circuit evaporator to maintain the freezer interior at a desired temperature or within a desired temperature range.
Abstract:
Disclosed are a method and apparatus for chilling food product, employing (A) cooling means comprising (1) a rotatable drum, (2) means in said drum for urging pieces through said drum, (3) cryogen dispensing means, and (4) means for rotating said drum; (B) feeding means which includes means for automatically sensing the mass flow rate at which said pieces are being fed into said inlet and for generating electrical signals corresponding to said rate; (C) electronic control means responsive to said signals and temperature inputs for preventing premature flow of cryogen and for automatically controlling the rate at which cryogen is fed so as to lower the temperature of said pieces to the desired exit temperature.
Abstract:
A method for providing refrigeration such as to an insulated enclosure wherein a defined multicomponent refrigerant fluid undergoes a phase change coupled with Joule-Thomson expansion to generate refrigeration over a wide temperature range which may comprise from ambient to low temperatures.
Abstract:
A food freezer for continuous freezing of food products utilizing a helical conveyor for transporting the food products through an enclosure having a first cooling zone in which the food products are cooled sufficiently to freeze the exterior surface, and a second cooling zone in which the interior of the food products are frozen. Refrigeration apparatus cools an atmosphere gas within the enclosure and baffle means directs the coldest gas through the food products in the first cooling zone and the gas from the first cooling zone is circulated to the second cooling zone where it passes across the food products in a direction opposite to the direction of travel through the second cooling zone.
Abstract:
A cryogenic freezer having a thermally insulated tunnel-like enclosure with an entrance and an exit and means for conveying products being frozen therethrough. Products are contacted with liquid cryogen at a region generally near the entrance and a blower located closer to the entrance than to the exit controls flow of cryogen vapor. Upstream and downstream baffles and dampers associated with blower are linked together for complementary movement to selectively regulate the upstream and downstream flow of vapor discharged from the blower. Additional blowers circulate the cold cryogenic vapor transverse to the direction of the conveying means. The temperature of vapor leaving the region of the entrance is monitored the orientation of the baffle and damper arrangement is adjusted in accordance with the temperature monitored. The food products can be contacted by liquid nitrogen in a reservoir facilitates cleaning and retards inefficient vaporization.