Small and micro laboratory liquid nitrogen machine

Small and micro laboratory liquid nitrogen machine is a small on-site liquid nitrogen preparation equipment designed specifically for scientific research, teaching, and medical experimental environments. It can directly separate and liquefy nitrogen from the air in the laboratory, providing high-purity liquid nitrogen as needed.

　　Small and micro laboratory liquid nitrogen machineIt is a small on-site liquid nitrogen preparation equipment designed specifically for scientific research, teaching, and medical experimental environments. It can directly separate and liquefy nitrogen from the air in the laboratory, providing high-purity liquid nitrogen as needed. Compared to traditional methods that rely on external procurement of steel cylinders or Dewar tanks, laboratory liquid nitrogen machines significantly improve the autonomy, safety, and economy of liquid nitrogen supply, especially suitable for scenarios that require high stability of liquid nitrogen such as cell cryopreservation, superconducting experiments, low-temperature physics, and material testing.

1、 Working principle

　　Small and micro laboratory liquid nitrogen machineEssentially, it is a miniature air separation and liquefaction system based on the principles of low-temperature distillation and gas liquefaction. The entire preparation process usually includes the following steps:

Air intake and compression: The ambient air is efficiently filtered and enters the oil-free air compressor, where it is pressurized to 5-8 bar. The use of oil-free compression can avoid oil vapor pollution in subsequent systems and ensure the purity of liquid nitrogen.

Deep purification: Compressed air is sequentially passed through a freeze dryer, precision filter, and dual tower molecular sieve adsorption device to remove moisture, carbon dioxide, oil mist, and dust. This step is crucial to prevent blockages in the pipeline due to impurity freezing in the low-temperature section.

Pre cooling and heat exchange: The purified high-pressure air enters the main heat exchanger (mostly a plate fin structure) and undergoes counter current heat exchange with the low-temperature nitrogen gas flowing back, gradually reducing the temperature to nearly -190 ℃.

Low temperature separation and liquefaction: The cooled air enters the distillation tower integrated in the vacuum insulated cold box, and separation is achieved by utilizing the boiling point difference between nitrogen (boiling point -195.8 ℃) and oxygen (boiling point -183 ℃). The nitrogen rich gas is enriched at the top of the tower and further cooled and liquefied through throttling expansion or micro turbine expansion.

Liquid nitrogen collection and use: The generated liquid nitrogen flows into a standard laboratory Dewar flask (commonly with a capacity of 30-100L), which can be accessed by users at any time; Unliquefied nitrogen gas is used as reflux gas for heat exchange and then discharged to achieve energy recovery.

The entire cycle is usually based on an improved Linde cycle, with some models introducing small turbine expanders to improve energy efficiency.

2、 System composition

Oil free compressor unit: low noise, high reliability, suitable for indoor continuous operation;

Air purification system: molecular sieve tower with multi-stage filters and automatic switching regeneration;

Cold Box: Integrated heat exchanger, distillation column, expansion valve, etc., with overall vacuum insulation;

Control system: based on embedded PLC or microprocessor, supporting automatic start stop, liquid level monitoring, fault alarm, and remote communication (such as Wi Fi or Ethernet);

Liquid storage interface: compatible with standard laboratory Dewar flasks, some models have built-in small storage tanks;

Safety protection devices: including oxygen concentration sensors, overpressure relief valves, overheat protection, residual current circuit breakers, etc.

3、 Technical features and performance parameters

Daily production: usually 10-100 liters of liquid nitrogen per day, to meet the daily needs of single or multiple laboratories;

Nitrogen purity: ≥ 99.995% (4.5N), some models can reach 99.999% (5N), meeting the requirements of biological sample cryopreservation and precision experiments;

Energy consumption level: The unit energy consumption of the model is about 0.8-1.2kWh/L, significantly better than early products;

Noise control: The operating noise is generally below 55-60dB (A) and can be placed in a corner of the laboratory or next to a fume hood;

Small footprint: The overall size of the machine is about 0.5-1m2, and the height usually does not exceed 1.8 meters, making it easy to deploy in space constrained environments;

High degree of automation: supports 7 × 24-hour unmanned operation, with "one click start" and intelligent sleep function.