The cryogenic feeder is a specially constructed stainless steel heat exchanger designed to optimize heat transfer, using liquid nitrogen as a refrigerant. The feeder is suitable for precooling a wide variety of materials, including plastic, rubber, food and drugs to their embrittlement temperature for cryogenic grinding operations. Heavy-Duty components and simplicity of construction assure a durable and reliable cryogenic cooling system.

The cooling conveyor operates with high thermal efficiency resulting in lower nitrogen consumption. The material is cooled to it's embrittlement temerature traveling through the cooling conveyor. When the material is passed through one of our Pulva-Sizer® grinding machines, it is reduced to the required size. Some products can be reduced to as low as -325 mesh. The material to be ground is loaded into a feed hopper. From the hopper, the material enters the cooling conveyor where liquid nitrogen at -320 F is sprayed directly onto the material. The liquid nitrogen vaporizes to a gas by absorbing the required heat of vaporization from the feed material. Seeking thermal equilibrium, the cold nitrogen gas continues to cool the feed material toits embrittlement point.

A thermocouple and temperature controller are used to control and monitor the temperature within the cooling conveyor and the grinding mill discharge hopper. During the grinding stage, additional liquid nitrogen may be injected into the Pulva-Sizer® to remove heat caused by grinding.

Testing is available in Pulva's Testing Lab.



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