Nitrous oxide

Nitrous oxide accumulates in liquid oxygen; since it cannot dissolve, it blocks the fin channels, increasing the risk of CnHm accumulation. Blockage on the oxygen side of the membrane main cooler can lead to an explosion in the plate-fin heat exchanger, as it causes hydrocarbons to accumulate and creates potential hazards.

Nitrous oxide, commonly known as \"laughing gas\", cannot be effectively removed by molecular sieves, and its hazards include the following: 1. It sublimes into a solid form once it enters the main heat exchanger, causing blockages in the air passages of the heat exchanger. 2. Since its boiling point is higher than that of the oxygen and nitrogen components, it dissolves in the liquid oxygen at the bottom of the tower, preventing the production of high-purity liquid oxygen and gaseous oxygen products. 3. When it accumulates to a certain concentration in the liquid oxygen, it also precipitates in solid form, blocking the main cooling channels.

1. Upon entering the main heat exchanger, it sublimes into a solid form, thereby blocking the air channels in the heat exchanger. 2. Since its boiling point is higher than that of oxygen and nitrogen, it dissolves in the liquid oxygen at the bottom of the tower, which prevents the production of high-purity liquid oxygen and gaseous oxygen products. 3. When it reaches a certain concentration in the liquid oxygen, it also precipitates in solid form, blocking the main cooling channels. Like this

The molecular formula of nitrous oxide is N2O; it is also known as dinitrogen monoxide, and is commonly referred to as \"laughing gas\". The concentration of nitrous oxide in the atmosphere is approximately 3×10-9. As the ecological environment deteriorates, its concentration is increasing at a rate of 0.2% to 0.3% per year. Nitrous oxide generated by the oxidation and denitrification activities of soil microorganisms in soils and oceans accounts for 1/3 of the nitrous oxide content in the atmosphere, with the remaining 2/3 being of human origin. For example: the combustion of fossil fuels, organisms, and waste, wastewater treatment, fermentation sources, vehicle exhaust, etc., can all lead to the formation of N2O. Near N2O emission sources, the concentration of N2O in the atmosphere can exceed 3×10-6. Although N2O has inert chemical properties and neither causes corrosion nor explodes, its physical properties pose a threat to air separation. Its critical temperature is 309.7 K, and its critical pressure is 7.27 MPa; its triple point is at 182.3 K and 0.088 MPa. Under the pressure and temperature conditions of an air separation unit, it exhibits sublimation properties. At atmospheric pressure, its boiling point is 185 K, which is higher than that of N2, O2, and Ar; therefore, during the separation of oxygen and nitrogen, it will concentrate in liquid oxygen. The solubility of N2O in water is very low; therefore, N2O cannot be separated or removed from the process air after it passes through air filters, compressors, coolers, and water separators. Most of the N2O is carried into the molecular sieve purifier, and the adsorption capacity of molecular sieves for N2O is lower than that for CO2. N2O first penetrates through the adsorption bed and enters the distillation tower; moreover, during the co-adsorption of H2O, CO2, C2H2, and other hydrocarbons by the molecular sieve, CO2 is able to displace the N2O molecules that have been adsorbed by the molecular sieve. Therefore, molecular sieves cannot remove N2O either. In the main heat exchanger, the process air is cooled to near the liquefaction temperature; N2O condenses into a solid first, which can cause blockages in the air passages. At an air processing pressure of 0.6 MPa and a N2O concentration of 1×10-6, the condensation temperature of N2O is 113 K. In the distillation column, since N2O has a higher boiling point compared to N2, O2, and Ar, it dissolves in liquid oxygen, preventing the production of high-purity liquid and gaseous oxygen products at the bottom of the column. It has been determined that at an oxygen product purity of 99.5%, the average content of N2O is 1.4×10-5. Furthermore, when the liquid oxygen is not discharged sufficiently, N2O continues to accumulate in it; once the N2O content in the liquid oxygen exceeds 50×10-6, it will precipitate in solid form, blocking the channels of the main condensation evaporator. In the production of the rare gases krypton and xenon, as krypton and xenon are concentrated, N2O is also concentrated. The N2O content can range from 100×10-6 to 150×10-6. N2O does not burn on its own, but it can undergo thermal decomposition. This will affect the catalytic combustion removal of CH4 in crude krypton and xenon, as well as the adsorption of the generated water and carbon dioxide using molecular sieves. Due to environmental issues, the concentration of N2O in the air is continuously increasing. Moreover, industries such as electronics require an increasingly high purity for oxygen products (99.99%–99.9999%), so removing N2O from process air has become even more important than before. A better removal method is to find an appropriate molecular sieve, which can adsorb and remove H2O, CO2, C2H2, and N2O from the processed air in a molecular sieve purifier.

I’ve learned it, hehe, thanks :)

It belongs to the clogging medium; it accumulates in the main cooler of air separation, causing dry evaporation and dead-end boiling, which can lead to combustion and explosion accidents.