Cryogenic exhaust control system and freezer having same

Abstract

A freezer for a food product, includes a housing having an internal space with a processing atmosphere for reducing a temperature of the food product; and a pressure balance apparatus in communication with the processing atmosphere to restrict atmosphere external to the freezer from reaching the internal space, the pressure balance apparatus comprising at least one sensor exposed to the processing atmosphere for generating a first signal indicating an amount of oxygen (O 2 ) sensed at the internal space, and a blower disposed to direct a pressurized flow of the processing atmosphere to the internal space responsive to the first signal. A related method is also provided.

What is claimed: 
     
         1 . A freezer for a food product, comprising:
 a housing having an internal space with a processing atmosphere for reducing a temperature of the food product; and   a pressure balance apparatus in communication with the processing atmosphere to restrict atmosphere external to the freezer from reaching the internal space, the pressure balance apparatus comprising at least one sensor exposed to the processing atmosphere for generating a first signal indicating an amount of oxygen (O 2 ) sensed at the internal space, and a blower disposed to direct a pressurized flow of the processing atmosphere to the internal space responsive to the first signal,   
     
     
         2 . The freezer of  claim 1 , wherein the blower is disposed at an outlet of the internal space. 
     
     
         3 . The freezer of  claim 2 , further comprising a cryogen delivery pipe in fluid communication with the internal space for delivering cryogen to said internal space, and another sensor mounted proximate an inlet to the internal space.  4 , The freezer of  claim 2 , further comprising: an inlet exhaust in fluid communication with an inlet to the internal space, an outlet exhaust in fluid communication with the outlet to the internal space; and a main exhaust in fluid communication with the internal space. 
     
     
         5 . The freezer of  claim 2 , further comprising a nozzle in fluid communication with the blower for directing the pressurized flow at the outlet. 
     
     
         6 . The freezer of  claim 5 , wherein the nozzle is mounted to direct the pressurized flow toward the internal space. 
     
     
         7 . The freezer of  claim 1 , further comprising a controller in communication with the at least one sensor and the blower, the controller arranged to receive the first signal from said at least one sensor and generate a second signal to said blower responsive to said first signal for controlling the blower. 
     
     
         8 . A method of balancing a processing atmosphere in an internal space of a freezer for food products, comprising:
 sensing an amount of oxygen (O 2 ) becoming present in the processing atmosphere;   generating a first signal indicating the amount of oxygen sensed;   withdrawing a portion of the processing atmosphere and pressurizing said portion responsive to the first signal; and   discharging the pressurized portion to the processing atmosphere for pressurizing said atmosphere and preventing additional O 2  from becoming present in said atmosphere.   
     
     
         9 . The method of  claim 8 , further comprising injecting a cryogenic substance into the processing atmosphere. 
     
     
         10 . The method of  claim 9 , wherein the cryogenic substance is selected from the group consisting of liquid nitrogen (LIN), carbon dioxide (CO 2 ), and cold air. 
     
     
         11 . The method of  claim 8 , further comprising exhausting a portion of the processing atmosphere from at least one location of the internal space within the freezer. 
     
     
         12 . The method of  claim 8 , further comprising exhausting portions of the processing atmosphere from a plurality of locations of the internal space within the freezer. 
     
     
         13 . The method of  claim 12 , wherein the plurality of locations include at least an inlet and an outlet for the processing atmosphere within the freezer. 
     
     
         14 . The method of  claim 8 , further comprising conveying the food products through the processing atmosphere. 
     
     
         15 . The method of  claim 8 , further comprising generating a second signal responsive to the first signal to control the discharging of the pressurized portion to the processing atmosphere. 
     
     
         16 . The method of  claim 8 , further comprising purging any oxygen from the processing atmosphere.