Cryogenic spiral freezer

Abstract

An upwardly helical flow path of cryogen-rich air inside a cryogenic spiral freezer may be used to chill or freeze products.

What is claimed is: 
     
         1 . A cryogenic spiral freezer, comprising:
 a rotatable drum;   a conveyor belt support spiraling up and around the drum to form a spiral ramp, each full revolution of the conveyor belt support around the drum constituting a tier, the conveyor belt support not being connected to the rotatable drum;   an endless conveyor belt disposed on top of the conveyor belt support along a helical path;   a cryogen injection apparatus comprising a feed line leading to at least one manifold extending in between adjacent tiers of the conveyor belt support, each of said at least one manifold including at least one nozzle positioned and configured to inject cryogen downwardly towards the conveyor belt;   a cylindrical freezing chamber housing enclosing the drum, and conveyor belt support; and   a blower apparatus comprising at least one blower each one of which is associated with a corresponding blower inlet and a corresponding blower outlet, wherein each of said at least one blowers is adapted and configured to draw in cryogen-rich air from the corresponding inlet and blow cryogen-rich air out of the corresponding outlet to induce a helical flow path of cryogen-rich air above and parallel to the helical path of the conveyor belt.   
     
     
         2 . The cryogenic spiral freezer of  claim 1 , wherein the drum has a continuous outer surface that prevents a flow of gas into an interior of the drum. 
     
     
         3 . The cryogenic spiral freezer of  claim 1 , wherein the conveyor belt has a width W, and the freezing chamber housing is spaced from an outer edge of the conveyor belt by no more than 0.1 W. 
     
     
         4 . The cryogenic spiral freezer of  claim 1 , wherein the conveyor belt support has a continuous surface that supports at least all portions of the conveyor belt in between inner and outer edges of the conveyor belt and prevents a flow of gas through the conveyor belt support. 
     
     
         5 . The cryogenic spiral freezer of  claim 1 , further comprising:
 a take-up tower housing;   plurality of rollers disposed within an interior of the take-up tower housing that support travel of the conveyor belt through the take-up tower housing interior, wherein:
 the freezing chamber housing has an inlet and outlet allow travel of the conveyor belt into and out of the freezing chamber, respectively; 
 the freezing chamber inlet and outlet are in communication with the take-up tower housing interior; and 
 the interior of the freezing chamber housing is isolated from the interior of the take-up tower housing by a wall of the freezing chamber housing except for the freezing chamber housing inlet and outlet. 
   
     
     
         6 . The cryogenic spiral freezer of  claim 5 , further comprising a pair of parallel conveyor belt support rails supporting inner and outer edges of the conveyor belt as it travels through the interior of the take-up tower housing, the conveyor belt support rails connecting with a top of the conveyor rail support to support travel of the conveyor belt out of the freezing chamber housing and into the take-up tower housing interior. 
     
     
         7 . The cryogenic spiral freezer of  claim 5 , wherein:
 the take-up tower housing has a first opening communicating with an exterior of the take-up tower housing to form a product exit and a second opening communication with the exterior of the take-up tower housing to form a product entry where chilled or frozen product may be unloaded from the conveyor belt;   said spiral freezer further comprises a rear-most roller receives that travel of the conveyor belt therearound at a position located adjacent the product exit and a front-most roller that receives travel of the conveyor belt therearound at a position located adjacent the product entry where product to be chilled or frozen may be loaded onto the conveyor belt.   
     
     
         8 . The cryogenic spiral freezer of  claim 5 , further comprising a recirculation blower disposed adjacent the freezing chamber outlet and a recirculation passageway defined by an outer surface of the freezing chamber housing and an outer surface of a concave portion of the take-up tower housing, the recirculation passageway providing a gas flow passage communicating between the freezing chamber outlet and one or more air return openings formed in the freezing chamber housing, the recirculation blower oriented to draw in a portion of cryogen-rich air exiting the freezing chamber outlet and blow the drawn-in portion into the recirculation passageway. 
     
     
         9 . The cryogenic spiral freezer of  claim 1 , wherein said blower assembly comprises a plurality of blowers each one of which being associated with a blower inlet and a blower outlet, and said blower inlets are vertically aligned at one radial position with respect to an axis of the freezing chamber housing and said blower outlets are vertically aligned at another radial position with respect to the axis of the freezing chamber housing. 
     
     
         10 . The cryogenic spiral freezer of  claim 9 , wherein each of said blowers is driven by a common blower motor drive shaft which in turn is driven by a single blower motor. 
     
     
         11 . The cryogenic spiral freezer of  claim 1 , wherein each of said at least one blower is disposed outside the freezer chamber housing. 
     
     
         12 . The cryogenic spiral freezer of  claim 1 , wherein the conveyor belt support has a dimpled surface. 
     
     
         13 . The cryogenic spiral freezer of  claim 1 , wherein:
 the conveyor belt has a midline equidistant from inner and outer edges of the conveyor belt;   each of said at least one blower outlets is oriented along a corresponding axis; and   each of said at least one axes extends over the midline of the helical path parallel to a line tangent to the midline.   
     
     
         14 . The cryogenic spiral freezer of  claim 1 , wherein the induced helical flow of the cryogen-rich air is above and parallel to the helical path of the conveyor belt along the entire helical path of the conveyor belt. 
     
     
         15 . The method of  claim 1 , wherein:
 the conveyor belt has a midline equidistant between inner and outer edges of the conveyor belt;   the conveyor belt rotates around and up a cylindrical drum disposed in a center of the spiral freezer along the helical path through frictional engagement between the inner edge of the conveyor belt and an outer circumferential surface of the cylindrical drum; and   the midline of the conveyor belt is continuously supported by the conveyor belt support from a bottom of the helical path to a top of the helical path.