초록 ▼

An improved pressure swing adsorption process is disclosed for the recovery of two individual components from a multicomponent gas mixture. The process utilizes a first group of adsorbent beds selective for the secondary component product and a second group of beds selective for tertiary impurities

An improved pressure swing adsorption process is disclosed for the recovery of two individual components from a multicomponent gas mixture. The process utilizes a first group of adsorbent beds selective for the secondary component product and a second group of beds selective for tertiary impurities in the mixture. The gas mixture is passed through the first and second beds in series and high purity primary component product is discharged from the second beds. The secondary component product is recovered by desorption from the first beds. Product recovery is improved by recycling depressurization gas from the first beds and by several novel pressure equalization steps. The process can be used to recover high-purity hydrogen and carbon dioxide from a gas mixture containing these components along with minor amounts of methane, carbon monoxide, and nitrogen.

대표청구항 ▼

In the separation of a multicomponent gas mixture by pressure swing adsorption to recover as individual products a primary key component and a secondary key component, wherein the secondary key component is more strongly adsorbed than the primary key component and there is present in the multicompon

In the separation of a multicomponent gas mixture by pressure swing adsorption to recover as individual products a primary key component and a secondary key component, wherein the secondary key component is more strongly adsorbed than the primary key component and there is present in the multicomponent gas mixture one or more minor tertiary components at low concentrations which are less strongly adsorbed than the secondary key component, by passing the multicomponent gas mixture in an adsorption step through a first bed of adsorbent selective for retention of the secondary key component, passing the effluent from said first bed through a second bed of adsorbent selective for the retention of the secondary key component and of the one or more minor tertiary components, withdrawing from said second bed a high purity product stream of the primary key component, and continuing said passing of the multicomponent gas mixture through the first and second beds until the concentration of the secondary key component in the effluent from the first bed or the concentration of at least one of the tertiary components in said high-purity stream of primary key component from the second bed reach predetermined levels, or until a predetermined time period has elapsed; the improvement comprising discontinuing flow of the multicomponent gas mixture through said first and second beds at the end of said adsorption step and thereafter during a mutually extending time period: (1) depressurizing said first bed immediately after the discontinuing of flow through said first and second beds by withdrawing from said first bed a first gas stream comprising desorbed and void space gas until the concentration of the secondary key component reaches a predetermined level in said gas stream or until a predetermined pressure is reached; (2) evacuating said first bed by withdrawing therefrom a product stream of substantially pure secondary key component; (3) depressurizing said second bed by withdrawing therefrom a gas stream comprising desorbed and void space gas; and (4) purging said second bed by passing therethrough a stream of the primary key component whereby additional adsorbed components are desorbed and are withdrawn along with remaining void space gas in a purge effluent stream; and thereafter following said mutually extending time period: (5) further pressurizing said first and second beds to a pressure up to the pressure of the adsorption step by passing a portion of said high-purity product stream of primary key component into and through said second bed and passing pressurization effluent from said second bed into said first bed, whereby both beds are prepared for another cycle beginning with said adsorption step.