Which type of molecular sieve is the best for VPSA oxygen generating unit?

Answer 1

Molecular sieves are the “heart” of the VPSA-O2 system. The main performance requirements for the molecular sieves used for the VPSA oxygen plant are excellent adsorption performance, high yield, stable oxygen purity, uniform particle size, high solidity & abrasion resistance and long service life. The better the performance of the molecular sieve is, the larger the scale of a single set of VPSA oxygen equipment would be achieved.

Commonly used molecular sieve adsorbents are 5A, 10X, 13X, N-2, CaA, NaX, CaX, LiX, CNA-198, Li.X.RE, HX5A-980, etc. Taking the common CaA molecular sieve as an example, when the air passes through the adsorption tower equipped with CaA molecular sieve, N2 is adsorbed preferentially so that the oxygen flows out of the adsorption tower as the product gas because the quadrupole moment of nitrogen is much larger than that of oxygen and the Ca2+ on the surface of the CaA molecular sieve micropore is more effective in adsorbing N2 than adsorbing O2.

However, the adsorption capacity and selectivity of CaA molecular sieve adsorbent for nitrogen are still not high enough, resulting in low oxygen yield and high energy consumption of VPSA oxygen generation units. Compared with CaA and NaX molecular sieve adsorbents, LiX molecular sieve has higher oxygen production efficiency. Less LiX molecular sieve could be used for the same oxygen capacity, thus reducing the energy consumption and size of the VPSA and PSA oxygen generator. LiLSX molecular sieve's capacity for adsorbing nitrogen is greater than its capacity for adsorbing the oxygen component of air with a higher degree of Li-ion exchange and smaller radius of Li+. The number of Li+ in liLSX molecular sieve is twice that of Ca2+ in CaA molecular sieve adsorbent and nitrogen & oxygen separation coefficient is 2-5 times that of the traditional oxygen molecular sieves, which enables lithium molecular sieve to adsorb more nitrogen. When applied to VPSA & PSA oxygen units, the consumption of liLSX molecular sieve is only 1/4-1/5 that of CaA molecular sieve, which is conducive to lowering the total investment, increasing the oxygen yield and greatly reducing the power consumption.

Compared with ordinary molecular sieve, PU-8 lithium-based molecular sieve independently developed and manufactured by PKU Pioneer has a higher absorption capacity for nitrogen, and the nitrogen-oxygen separation coefficient is 8-10, which is the highest in China at present. PKU Pioneer's PU-8 oxygen adsorbent has been applied to 300+ VPSA & PSA oxygen generation units. Due to its higher oxygen yield, less loading amount of PU-8 adsorbent helps to minimize the operating load of the supporting power equipment, which substantially reduces the comprehensive investment and operating energy consumption of VPSA oxygen systems.

At the same time, PKU Pioneer's exclusive mechanical homogeneous spin loading technology ensures uniform distribution of the adsorbent. After primary loading, no replacement or refilling is required within 10 years under normal usage without the capacity decrease of the oxygen unit caused by the adsorbent pulverization. Based on PU-8 oxygen adsorbent, PKU Pioneer's complete sets of VPSA oxygen devices have been widely used in iron & steel, non-ferrous Metallurgy, glass & glass fiber, cement, pulp making, waste incineration, new energy batteries, refractory materials and other industrial fields to help customers optimize existing processes and achieve energy saving & profit lifting.