What is Liquid Nitrogen Generator?
Liquid nitrogen generators consist of a nitrogen gas generator that divides and extracts nitrogen gas from the oxygen molecules in the air. The generator has a cryocooler that is used for turning the nitrogen gas into a liquid by reducing its temperature to below its evaporation point of approx. -195.8 °C (-320 °F) and a vacuum-heat insulated vessel that stores the liquid nitrogen.
How Does a Liquid Nitrogen Generator Work?
Cryoplants typically comprise a pre-treatment, a cryogenic, and a compressor/expander section. During pre-treatment, freezable components which may damage cryogenic equipment - such as water and carbon dioxide - are removed by absorption. Other impurities (such as mercury) may also be removed by catalysis.
In a cryoplant`s liquid nitrogen generator, atmospheric air is pressurized by a compressor and fed into a buffer tank. From the buffer tank, this air is channelled towards a set of filters behind the cryoplant to remove impurities. Any remaining moisture is eliminated by an internal air dryer unit.
This treated air is further channelled towards a Pressure Swing Adsorption (PSA) module. Within this module, a carbon molecular sieve adsorbs oxygen and carbon monoxide molecules in an adsorption bed. Once this bed is saturated, the flow is switched to a second adsorption bed during which time the first bed is purged. Thus, by constantly switching the flow between these two adsorption beds, pure nitrogen gas is obtained and fed into a cryocooler located in a cryogenic storage vessel.