Apparatus and method for generating ice pellets

Abstract

An apparatus and method for generating ice pellets, in particular for controlling the properties of the generated ice pellets. The apparatus comprises a pellet generation region; at least one nozzle configured to supply a plurality of water droplets to the pellet generation region; a liquefied gas supply configured to deliver a liquefied gas to the pellet generation region to thereby freeze the water droplets to generate a plurality of ice pellets; at least one temperature measuring device configured to obtain data indicative of the temperature of the ice pellets at generation; and a control system configured to adjust the flow rate of water and/or liquefied gas to thereby control the temperature of the ice pellets at generation.

We claim: 
     
         1 . An apparatus for generating ice pellets, the apparatus comprising:
 a pellet generation region;   at least one nozzle configured to supply a plurality of water droplets to the pellet generation region;   a liquefied gas supply configured to deliver a liquefied gas to the pellet generation region to thereby freeze the water droplets to generate a plurality of ice pellets;   at least one temperature measuring device configured to obtain data indicative of the temperature of the ice pellets at generation; and   a control system configured to adjust the flow rate of water and/or liquefied gas to thereby control the temperature of the ice pellets at generation, wherein a temperature measuring device is located in or proximate to the pellet generation region.   
     
     
         2 . The apparatus according to  claim 1 , further comprising a conduit configured to receive generated ice pellets from the pellet generation region, and a pellet gun configured to receive ice pellets from the conduit and propel them towards a target. 
     
     
         3 . The apparatus according to  claim 2 , wherein a temperature measuring device is located in the pellet gun. 
     
     
         4 . The apparatus according to  claim 3 , wherein the pellet gun comprises an unblocking device configured to dislodge ice pellets from the conduit. 
     
     
         5 . The apparatus according to  claim 1 , further comprising a particle filter configured to pass generated ice pellets smaller than a threshold size. 
     
     
         6 . The apparatus according to  claim 5 , wherein the particle filter comprises a mesh. 
     
     
         7 . The apparatus according to  claim 6 , wherein the particle filter comprises a rotatable disc comprising a plurality of holes. 
     
     
         8 . The apparatus according to  claim 5 , wherein the particle filter comprises:
 a first rotatable disc comprising a first plurality of holes;   a second rotatable disc comprising a second plurality of holes; and   a distributor configured to selectively direct the ice pellets to the first rotatable disc or the second rotatable disc;   wherein the average size of the first plurality of holes is smaller than the average size of the second plurality of holes.   
     
     
         9 . The apparatus according to  claim 1 , further comprising a pellet storage region configured to store generated ice pellets 
     
     
         10 . The apparatus according to  claim 9 , further comprising an air feed configured to deliver air to the pellet storage region. 
     
     
         11 . The apparatus according to  claim 10 , wherein the air feed is configured to direct air to form a fluidised bed with the ice pellets. 
     
     
         12 . The apparatus according to  claim 11 , wherein the air feed is configured to direct air to form a cyclonic air current. 
     
     
         13 . The apparatus according to  claim 1 , wherein the apparatus comprises a sampling port configured to allow removal of the ice pellets. 
     
     
         14 . The apparatus according to  claim 1 , wherein the at least one nozzle comprises a variable aperture. 
     
     
         15 . The apparatus according  claim 1 , further comprising a blade or jaws configured to mechanically deform the generated ice pellets. 
     
     
         16 . The apparatus according to  claim 1 , wherein the liquefied gas is liquefied nitrogen, liquefied oxygen, liquefied helium or a combination thereof. 
     
     
         17 . An apparatus for generating ice pellets, the apparatus comprising:
 a pellet generation region;
 at least one nozzle configured to supply a plurality of water droplets to the pellet generation region; 
 a liquefied gas supply configured to deliver a liquefied gas to the pellet generation region to thereby freeze the water droplets to generate a plurality of ice pellets; 
 at least one sensor configured to obtain data indicative of the particle size distribution of the ice pellets at generation; and 
 a control system configured to adjust the flow rate of water and/or liquefied gas based on the output of the sensor. 
   
     
     
         18 . The apparatus according to  claim 17 , wherein the liquefied gas is liquefied nitrogen, liquefied oxygen, liquefied helium or a combination thereof. 
     
     
         19 . A method of generating ice pellets, the method comprising the steps of:
 supplying a plurality of water droplets to a pellet generation region;   delivering a liquefied gas to the pellet generation region to thereby freeze the water droplets to generate a plurality of ice pellets;   measuring the temperature of the generated ice pellets; and   adjusting the flow rate of water and/or liquefied gas to thereby control the temperature of the generated ice pellets and
 propelling said ice pellets towards a target.