The working principle of nitrogen generator is as follows:
Nitrogen generator adopts the principle of Pressure Swing Adsorption (PSA) to separate the air at room temperature to produce high purity nitrogen. Usually two adsorption towers are connected in parallel, and the imported PLC controls the imported pneumatic valves to run automatically, alternately carrying out pressurized adsorption and decompression regeneration, completing the separation of nitrogen and oxygen, and obtaining the required high-purity nitrogen.
The molecular sieve can adsorb oxygen and nitrogen in the air at the same time, and its adsorption amount rises with the rise of pressure, and there is no obvious difference between the equilibrium adsorption amount of oxygen and nitrogen under the same pressure.
Therefore, it is difficult to complete the effective separation of oxygen and nitrogen only by the change of pressure. If the adsorption rate is further considered, the adsorption characteristics of oxygen and nitrogen can be effectively distinguished. Oxygen molecule diameter than the nitrogen molecule is small, so the diffusion speed is hundreds of times faster than the nitrogen, so the carbon molecular sieve adsorption of oxygen is also very fast, adsorption of about 1 minute to reach more than 90%; and at this time the nitrogen adsorption amount is only 5% or so, so at this time adsorption of oxygen, and the rest of the body is largely nitrogen.
Expanded Information
Deep-cooling nitrogen production can not only produce nitrogen but also liquid nitrogen, to meet the requirements of the process of liquid nitrogen, and can be stored in the liquid nitrogen tank, when there is a nitrogen intermittent load or the air separation equipment for minor repairs, liquid nitrogen in the tank into the carburetor is heated, and then sent to the product of the nitrogen pipeline to meet the demand for nitrogen for the process equipment. The liquid nitrogen in the storage tank enters the vaporizer and is heated and sent to the product nitrogen pipeline to meet the demand of the process device.
The operation cycle of deep-cooling nitrogen generation (referring to the interval between two large heating) is generally more than one year, therefore, deep-cooling nitrogen generation is generally not considered as a backup. And the variable pressure adsorption nitrogen production can only produce nitrogen, there is no backup means, a single set of equipment can not guarantee the continuous long cycle operation.
Membrane air separation of nitrogen, air compressed by the compressor filtered into the polymer membrane filter, due to the different solubility and diffusion coefficients of various gases in the membrane, resulting in different gases in the membrane relative permeability rate is different. According to this characteristic, various gases can be divided into "fast gas" and "slow gas".
When the mixed gases in the membrane on both sides of the pressure difference, the permeation rate of relatively fast gases, such as water, hydrogen, helium, hydrogen sulfide, carbon dioxide, etc. through the membrane, in the membrane permeation side is enriched, while the permeation rate of relatively slow gases, such as methane, nitrogen, carbon monoxide and argon, etc., the gas is retained in the side of the membrane to be enriched, so as to achieve the purpose of the separation of mixed gases.