Hydrogen separation and purification Reposted

Thread Content

For the separation and purification of hydrogen by pressure swing adsorption, a process flow that involves multiple towers for pressure equalization and one tower for adsorption is generally used. Pressure swing adsorption (PSA) technology is based on the physical adsorption of gas molecules by the internal surface of specific adsorbents (porous solid materials). Utilizing the property that these adsorbents readily adsorb high-boiling-point components at the same pressure while having difficulty adsorbing low-boiling-point components, as well as the fact that the amount of adsorption increases under high pressure and decreases under low pressure, the feed gas is passed through an adsorption bed at a certain pressure; thereby, the high-boiling-point impurity components are selectively adsorbed, while the low-boiling-point hydrogen gas passes through the adsorption bed unadsorbed, achieving the separation of hydrogen from the impurity components. After adsorption is complete, the adsorbent is desorbed under reduced pressure of the adsorbed impurity components, thereby regenerating the adsorbent so that it can once again be used to adsorb and separate the impurity components from the hydrogen source. The adsorption tower alternates between adsorption, desorption, and adsorption preparation processes to achieve continuous hydrogen production. During the adsorption-desorption process, a certain pressure of product hydrogen remains in the adsorption tower after adsorption is complete. This pure hydrogen is used to equalize the pressure and clean the other pressure-equalization towers that have just completed desorption. By doing so, not only is the hydrogen remaining in the adsorption tower utilized, but the rate at which pressure builds up in the adsorption tower is also reduced, which in turn reduces the degree of fatigue of the tower. This approach effectively achieves the goal of hydrogen separation.