According to the principle of psa, high quality Du carbon molecular sieve was used as adsorbent to prepare nitrogen from Dao air under certain pressure. After purification and drying of compressed air, pressure adsorption and decompression desorption were carried out in the adsorber. Due to aerodynamic effect, the diffusion rate of oxygen in carbon molecular sieve micropores is much higher than that of nitrogen. Carbon zeolite preferentially adsorbs oxygen, nitrogen in the gas phase enrichment to form the finished nitrogen. After that, the adsorbent desorbs impurities such as oxygen to achieve regeneration. The system is generally equipped with two adsorption towers, one for nitrogen production and the other for desorption and regeneration. The opening and closing of pneumatic valve is controlled by PLC program controller to make the two towers circulate alternately, so as to achieve the purpose of continuous production of high quality nitrogen. The whole system consists of the following components: compressed air purification unit, air storage tank, oxygen and nitrogen separation unit, nitrogen buffer tank.
1. Compressed air purification device
The compressed air provided by the air compressor first enters the compressed air purification plant. Most of the oil, water and dust in the compressed air are removed through a pipework filter, which further removes the water, oil and dust through a freeze-dryer and then deep purifies through an ultrafine filter. According to the working conditions of the system, a set of compressed air oil remover is specially designed to prevent possible oil seepage and provide adequate protection for the carbon molecular sieve. Strict air purification component design ensures the service life of the carbon molecular sieve. The clean air treated by the module can be used for instrument air.
2. Gas storage tank
The role of the gas storage tank is to reduce the air flow pulsation, play a buffering role, reduce the pressure fluctuation of the system, make the compressed air pass through the compressed air purification device, to fully remove oil and water impurities, and reduce the load of the subsequent psa adsorption oxygen and nitrogen separation device. At the same time, when the adsorption tower is switched, it also provides a large amount of compressed air for the psa oxygen and nitrogen separation device, which can boost the pressure rapidly in a short time, making the pressure inside the adsorption tower rise to the working pressure rapidly, ensuring the reliable and stable operation of the equipment.
3. Oxygen and nitrogen separation device
Both a and B adsorption towers are equipped with special carbon molecular sieves. Clean compressed air enters the inlet end of Tower A and flows to the outlet end through the carbon molecular sieve. O2, CO2 and H2O are absorbed by it, and the product nitrogen flows out of the adsorption tower outlet. After a period of time, the adsorption of carbon molecular sieve in tower A reaches saturation. At this point, tower A automatically stops adsorption, and the compressed air enters tower B to absorb oxygen and produce nitrogen, and the molecular sieve of tower A is regenerated. Molecular sieve regeneration is achieved by rapidly reducing the adsorption tower to atmospheric pressure and removing the adsorbed O2, CO2 and H2O. The adsorption and regeneration of the two towers are alternately carried out to complete the separation of oxygen and nitrogen and the continuous output of nitrogen. The above process is controlled by PLC. When the purity of nitrogen at the outlet is set, the PLC program will open the automatic exhaust valve and automatically empty the unqualified nitrogen to ensure that the unqualified nitrogen does not flow to the gas point. Noise reduction is to reduce the noise of gas emission to less than 75dBA.
4. Nitrogen buffer tank
Nitrogen buffer tank is used to balance the pressure and purity of nitrogen separated from nitrogen and oxygen separation system to ensure the stable and continuous supply of nitrogen. At the same time, after the adsorption tower is switched, part of its gas is added to the adsorption tower, which, on the one hand, helps the adsorption tower to pressurize and on the other hand protects the bed, playing a very important auxiliary role in the operation of the equipment.
Post time: Aug-22-2020