Why can't CMS be "universal"?
The "specificity" of carbon molecular sieves is determined by the material properties + equipment process + application scenarios. The key differences are as follows:
1. The nitrogen production principles are different, and the functions of CMS are "not aligned"
Deep cold air separation nitrogen production machine: It separates N₂/O₂ through the liquefaction of air at low temperatures. CMS is not involved throughout the process. If CMS is mistakenly used, it will not only be completely ineffective, but also because CMS is prone to cracking at low temperatures and blocking the distillation tower pipes, the equipment will be scrapped!
Membrane separation nitrogen production machine: It separates O₂/N₂ based on the difference in permeation rates of high molecular membranes. It also does not require CMS. Mistaken use will occupy equipment space, increase resistance, and reduce the lifespan of the membrane components.
PSA nitrogen production machine (the only type that requires CMS): It relies on CMS for the preferential adsorption of O₂, through the "pressurized adsorption - depressurized desorption" cycle to produce nitrogen. However, the adsorption pressure (0.4-1.2 MPa), cycle time (30-180 seconds), and target purity (95%-99.999%) of different PSA equipment vary greatly. The requirements for CMS's "adsorption capacity, selectivity, and kinetics" are completely different.
2. The equipment process parameters do not match, CMS "does not fit"
Even for PSA nitrogen production machines, the size of the adsorption towers, the gas distribution method (radial flow vs axial flow), and the control system (PLC program differences) also affect the actual performance of CMS:
Devices with low adsorption pressure (such as 0.6 MPa): They require CMS to maintain a high O2 adsorption capacity at low partial pressures, otherwise "it cannot be fully absorbed", resulting in less gas production and low purity;
Short cycle devices (such as 30s per cycle): They require CMS to "quickly adsorb and quickly desorb", if using a slow-response CMS, it will cause O₂to enter the desorption stage before being fully absorbed, resulting in a sudden drop in purity;
High-purity devices (such as 99.999%): They require CMS to have a selectivity of O₂> 4:1, if using ordinary CMS (selectivity 2:1), O₂will "leak through", and it will never reach 6N grade.
3. The application scenarios have different requirements, CMS "ability boundaries" are exceeded
Electronic industry (99.999% nitrogen): It requires CMS with extremely uniform micropores (0.35-0.45 nm), to avoid N₂ being mistakenly adsorbed;
Coal mine nitrogen injection (95%-98% nitrogen): It requires CMS to be resistant to dust and humidity (high humidity in underground air), ordinary CMS is prone to powdering and blocking;
Chemical explosion-proof scenarios: It requires CMS to not produce sparks (no static electricity generated by friction), metal-based CMS may not be applicable.
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