What is the main equipment of a liquid nitrogen machine?

　　Liquid nitrogen generator equipmentWhat is the main equipment of a liquid nitrogen generator?

　　1. Air filtration

　　In order to reduce wear on the moving surfaces of the internal machinery of the air compressor and ensure air quality, the air must pass through an air filter to remove dust and other impurities before entering the air compressor. Air compressors mostly use coarse or medium-efficiency filters for intake.

　　2. Air compressor

　　According toLiquid nitrogen generator equipmentits working principle, air compressors can be divided into two categories: positive displacement and dynamic. Commonly used air compressors include reciprocating piston compressors, centrifugal compressors, and screw compressors.

　　3. Air cooler

　　Before entering the air dryer and air separation column, it can lower the temperature of the compressed air, prevent drastic temperature fluctuations in the column, and separate out most of the moisture in the compressed air. Generally, nitrogen coolers (consisting of a water cooling tower and an air cooling tower: the water cooling tower uses waste gas from the air separation column to cool the circulating water, and the air cooling tower uses circulating water from the water tower to cool the air) and Freon air coolers are used.

　　4. Liquid nitrogen generator equipment - Air dryer

　　Even after passing through the air cooler, compressed air still contains a certain amount of moisture, carbon dioxide, acetylene, and other hydrocarbons. Frozen moisture and carbon dioxide accumulate in the air separation column, clogging channels, pipes, and valves. Acetylene accumulating in liquid oxygen poses an explosion risk, and dust causes wear and tear on the machinery. To ensure the long-term safe operation of the air separation equipment, special purification equipment must be installed to remove these impurities. Common methods for air purification are adsorption and freezing. Molecular sieve adsorption is widely used in small and medium-sized nitrogen generators in China.

　　5. Liquid nitrogen generator equipment - Air separation column

　　The air separation column mainly includes a main heat exchanger, liquefier, rectifying column, and condenser-evaporator. The main heat exchanger, condenser-evaporator, and liquefier are new combined wall-type heat exchangers with an all-aluminum metal structure, small average temperature difference, and heat exchange efficiency reaching 98-99%. The rectifying column is the air separation equipment. The type of column equipment is classified according to its internal structure. A column with sieve plates installed is called a sieve plate column; one with foam plates is a foam column; and one with packed filling is called a packed column. Due to its simple structure, easy manufacturing, and high plate efficiency, the sieve plate is widely used in air separation rectifying columns. Packed columns are mainly used for rectifying columns with a diameter of less than 0.8 meters and a height of less than 7 meters. Bubble cap columns are complex in structure, difficult to manufacture, and rarely used.

　　6. Turbo expander

　　Liquid nitrogen generator equipmentA rotating blade machine that generates cold, it is a gas turbine used under low-temperature conditions. Turbo expanders are classified into axial flow, centrifugal outflow, and centrifugal radial axial flow types according to the gas flow in the impeller. According to whether the gas continues to expand on the impeller, they are divided into reaction type and impulse type. If it continues to expand, it is a reaction type; if not, it is an impulse type. Single-stage centrifugal radial axial flow reaction type turbo expanders are widely used in air separation equipment. Low-temperature air separation nitrogen generation equipment is complex, has a large footprint, high infrastructure costs, high initial equipment investment, high operating costs, slow production cycle (12~24H), high installation requirements, and a long cycle. Considering equipment, installation, and infrastructure factors, for equipment below 3500Nm3/h, the investment scale of PSA equipment of the same specification is 20% to 50% lower than that of low-temperature air separation equipment. Low-temperature nitrogen generation units are suitable for large-scale industrial nitrogen production, but are not economical for small and medium-sized nitrogen production.