System and method for producing block ice treated with nitrogen substitution

Abstract

A system for producing block ice may include a nitrogen gas supplying unit for supplying nitrogen gas under pressure; a cooled nitrogen-dissolved water producing unit for producing nitrogen-dissolved water, which is provided with a water receiving tank for storing material water, a cooler for cooling the water stored in the water receiving tank, and a nitrogen gas injector for injecting nitrogen gas supplied from the nitrogen gas supplying unit into the water stored in the water receiving tank; and a nitrogen-substitution block ice producing unit, which is provided with a plurality of ice cans immersed in a brine tank kept at a freezable temperature for water, a filling device for filling each of the ice cans with the nitrogen-dissolved water supplied from the nitrogen-dissolved water producing unit, and a gas injector for injecting nitrogen gas supplied from the nitrogen gas supplying unit into an unfrozen portion of the nitrogen-dissolved water.

What is claimed is: 
     
         1 . A system for producing block ice that is treated with nitrogen substitution comprising:
 (a) a nitrogen gas supplying unit provided with a feeder for supplying nitrogen gas under a predetermined pressure;   (b) a nitrogen-dissolved water producing unit for producing nitrogen-dissolved water, the nitrogen-dissolved water producing unit including a water receiving tank for storing material water, a cooler for cooling the water stored in the water receiving tank, and a nitrogen gas injector for injecting nitrogen gas supplied from the nitrogen gas supplying unit into the water stored in the water receiving tank; and   (c) a nitrogen-substitution block ice producing unit including a plurality of ice cans immersed in a brine tank that is kept at a freezable temperature for water, a filling device for filling each of the ice cans with the nitrogen-dissolved water supplied from the nitrogen-dissolved water producing unit, and a gas injector for injecting nitrogen gas supplied from the nitrogen gas supplying unit into an unfrozen portion of the nitrogen-dissolved water.   
     
     
         2 . The system for producing block ice that is treated with nitrogen substitution according to  claim 1 , wherein an amount of dissolved oxygen in the nitrogen-dissolved water that is produced in the nitrogen-dissolved water producing unit is not more than 0.3 mg/L at a temperature in the vicinity of 0° C. 
     
     
         3 . The system for producing block ice that is treated with nitrogen substitution according to  claim 2 , wherein the filling device for filling each of the ice cans with the nitrogen-dissolved water comprises a pouring tank for storing the nitrogen-dissolved water supplied from the nitrogen-dissolved water producing unit, and a plurality of pouring ports formed at a bottom of the pouring tank in such a way that each one of the ice cans is filled with the nitrogen-dissolved water through each one of the pouring ports. 
     
     
         4 . The system for producing block ice that is treated with nitrogen substitution according to  claim 1 , wherein the filling device for filling each of the ice cans with the nitrogen-dissolved water comprises a pouring tank for storing the nitrogen-dissolved water supplied from the nitrogen-dissolved water producing unit, and a plurality of pouring ports formed at a bottom of the pouring tank in such a way that each one of the ice cans is filled with the nitrogen-dissolved water through each one of the pouring ports. 
     
     
         5 . A method for producing block ice that is treated with nitrogen substitution comprising:
 producing cooled nitrogen-dissolved water by cooling material water while injecting nitrogen gas into the material water;   filling an ice can kept at a freezable temperature for water with the cooled nitrogen-dissolved water; and   freezing the nitrogen-dissolved water while receiving injection of nitrogen gas into an unfrozen portion of the nitrogen-dissolved water at least for a selected portion of time from start to finish of freezing.   
     
     
         6 . The method for producing block ice that is treated with nitrogen substitution according to  claim 5 , wherein an amount of dissolved oxygen in the cooled nitrogen-dissolved water is not more than 0.3 mg/L at a temperature in the vicinity of 0° C. 
     
     
         7 . The method for producing block ice that is treated with nitrogen substitution according to  claim 6 , wherein injection of nitrogen gas into the unfrozen portion of the nitrogen-dissolved water is stopped halfway through freezing the nitrogen-dissolved water. 
     
     
         8 . The method for producing block ice that is treated with nitrogen substitution according to  claim 5 , wherein injection of nitrogen gas into the unfrozen portion of the nitrogen-dissolved water is stopped halfway through freezing the nitrogen-dissolved water. 
     
     
         9 . The method for producing block ice that is treated with nitrogen substitution according to  claim 5 , wherein a duration of time from start to finish of freezing the nitrogen-dissolved water is 48 hours for producing pillar-shaped block ice measuring 280 mm long, 550 mm wide, and 1080 mm high.