PSA separation

Pressure Swing Adsorption

Category:

CO2 capture plant

Product Overview

It mainly processes low-pressure, high-CO₂-concentration gas sources (such as lime kiln gas, flue gas, and fermentation tail gas). The CO₂ concentration is increased from 8–13% to ≥95%, with a recovery rate of 70–90%.

Mature process, simple operation, and stable operation.
High-purity CO₂ product and high recovery rate.
Low energy consumption and good economic efficiency.
Fully automatic control with remote monitoring capability.
Adapts to fluctuations in gas volume and composition, enabling flexible operation.

The selectivity of the adsorbent and pressure changes

The core of PSA lies in the selectivity of the adsorbent and the pressure variation. Adsorbents are usually porous solid materials, such as zeolite molecular sieves, activated carbon or alumina.A PSA system is typically composed of two or more adsorption towers, ensuring continuous gas production by alternately switching the adsorption and desorption processes. When one tower is in the high-pressure adsorption stage, the other tower is in the low-pressure desorption stage, and this cycle repeats itself.

Adsorption Stage (High Pressure):

When a mixed gas stream is fed into an adsorption tower containing adsorbent under high pressure, the adsorbent preferentially adsorbs one or several specific components.

For example, in nitrogen production, carbon molecular sieves exhibit stronger adsorption capacity for oxygen and carbon dioxide than for nitrogen. Consequently, under high pressure, oxygen and carbon dioxide are captured by the adsorbent, while nitrogen escapes as the non-adsorbed component, yielding a high-purity nitrogen product.

Desorption Stage (Low Pressure):

Once the adsorbent reaches saturation, gas flow is halted. Pressure reduction (typically to atmospheric pressure or vacuum) releases the adsorbed components from the adsorbent.

As pressure decreases, the adsorbent's adsorption capacity weakens. Previously adsorbed gases like oxygen and carbon dioxide are “released,” regenerating the adsorbent for the next adsorption cycle.