Separation of gas mixtures by vacuum swing adsorption (VSA) in a two-adsorber system

Claim 1

Process for adsorptive separation of crude gas mixtures by vacuum swing adsorption in two containers filled with adsorbent said containers being adsorbers A and B which are provided with a bottom and top inlet and discharge end, the gas content which is adsorbed less strongly, if at all, (raffinate) being obtained under reduced pressure, said process comprising (F1) operating the two adsorbers A and B alternately so that the crude gas fed into the adsorbers is not stopped at any time during the course of the process, a vacuum pump remaining continuously connected to the adsorbent packing, (a) at time t 1 depressurizing adsorber A at the top end, the gas released in this way flowing into the top end of an evacuated adsorber B, adsorber A being connected at the bottom end to a vacuum pump and adsorber B being filled at the bottom end with crude gas, (b) at time t 2 evacuating adsorber A and filling adsorber B at the top end with raffinate from a raffinate reservoir R, adsorber B being filled at the bottom end under reduced pressure with crude gas, (c) at time t 3 , evacuating adsorber A at the bottom end and filling adsorber B the bottom end with crude gas, or crude gas flows through adsorber B at the bottom end, starting at a pressure of 1 bar, and stripping off the gas content which is adsorbed less strongly as the product at the top end of adsorber B, (d) proceeding further with the process by repeating the times t 1 , t 2 and t 3 adsorbers A/B being changed over, or alternatively in a two-adsorber VSA process (e) at time t 1 depressurizing adsorber A at the top end, the gas released in this way flows into the top end of the adsorber B, which is operated under reduced pressure, charging adsorber A at the bottom end with crude gas, adsorber B is connected at the bottom end to a vacuum pump, but the pressure in adsorber B rises here due to the entry of gas from adsorber A, and the pressure in adsorber A falls, (f) at time t 2 the process proceeding analogously to (1b), (g) at time t 3 the process proceeding analogously to (1c), (h) the process proceeding further by repeating the times t 1 , t 2 and t 3 , adsorbers A/B being changed over.