Spiral freezer with precooler

Abstract

A freezer includes a housing having a space therein for receiving a cryogenic gas, and an inlet and an outlet in communication with the space; a conveyor belt having an outer edge and being arranged for movement through the space for transferring a product from the inlet through to the outlet; a solid longitudinal member disposed in the space adjacent the outer edge for segregating the space into an upper chamber and a lower chamber; and a transfer duct operatively associated with the housing and having a first opening in communication with the upper chamber for receiving the cryogenic gas from the upper chamber and a second opening in communication with the lower chamber for expelling the cryogenic gas into the lower chamber.

What is claimed is: 
     
         1 . A freezer apparatus, comprising:
 a housing having a space therein for receiving a cryogenic gas, and an inlet and an outlet in communication with the space;   a conveyor belt having an outer edge and being arranged for movement through the space for transferring a product from the inlet through to the outlet;   a solid longitudinal member disposed in the space adjacent the outer edge of the conveyor belt for segregating the space into an upper chamber and a lower chamber; and   a transfer duct operatively associated with the housing and having a first opening in communication with the upper chamber for receiving the cryogenic gas from the upper chamber and a second opening in communication with the lower chamber for expelling the cryogenic gas into the lower chamber.   
     
     
         2 . The freezer apparatus of  claim 1 , further comprising a fan disposed in the transfer duct for moving the cryogenic gas from the upper chamber through the transfer duct into the lower chamber. 
     
     
         3 . The freezer apparatus of  claim 2 , further comprising at least one passageway in communication with the upper chamber for introducing the cryogenic gas into the upper chamber, and a valve interposed in the at least one passageway for regulating flow of the cryogenic gas to the upper chamber. 
     
     
         4 . The freezer apparatus of  claim 3 , further comprising a controller in communication with the valve and the fan for generating a signal to control the valve and the fan to regulate an amount of the cryogenic gas introduced into the upper chamber and a flow rate of the cryogenic gas. 
     
     
         5 . The freezer apparatus of  claim 1 , further comprising a drum disposed in the space and having an exterior surface around which the conveyor belt moves. 
     
     
         6 . The freezer apparatus of  claim 1 , wherein the conveyor belt comprises a surface area selected from the group consisting of a solid surface and a mesh surface. 
     
     
         7 . The freezer apparatus of  claim 1 , wherein the transfer duct comprises a pipe mounted to a sidewall of the housing or optionally formed integral with the sidewall. 
     
     
         8 . The freezer apparatus of  claim 1 , further comprising a first exhaust in communication with the lower chamber, and a second exhaust in communication with the upper chamber. 
     
     
         9 . The freezer apparatus of  claim 1 , wherein the conveyor belt is arranged in a continuous loop. 
     
     
         10 . The freezer apparatus of  claim 1 , wherein a pressure of an upper atmosphere in the upper chamber and another pressure of a lower atmosphere in the lower chamber are greater than an ambient pressure external to the housing. 
     
     
         11 . The freezer apparatus of  claim 1 , wherein the cryogenic gas comprises at least one of nitrogen or carbon dioxide.