Pressure swing adsorption

Recovery rate is one of the key performance indicators for pressure swing adsorption. It is defined as the percentage of the absolute amount of the component to be recovered in the product obtained from the pressure swing adsorption unit, relative to the absolute amount of that same component in the feed gas entering the unit. Method 1: Given the following conditions: ⑴. The flow rate of the feed gas entering the pressure swing adsorption unit (F, nm3/h); ⑵. The concentration of the component to be recovered in the feed gas (XF, %); ⑶. The flow rate of the product gas obtained from the pressure swing adsorption unit (P, nm3/h); ⑷. The concentration of the recovered component in the product (XP, %). The recovery rate η of the recovered component is calculated as: η = P.XP / (F.XF) × 100%. Method 2: Given the following conditions: ⑴. The concentration of the component to be recovered in the feed gas (XF, %); ⑵. The concentration of the same component in the product (XP, %); ⑶. The concentration of the component in the desorbed gas (XW, %). Assume that the flow rates of the feed gas, product gas, and desorbed gas are respectively F, P, and W. From the material balance, we have: F = P + W. F.XF = P.XP + W.XW. The recovery rate is given by: P.XP / (F.XF) = (F.XF – W.XW) / (F.XF) = (F.XF – F.XW + P.XW) / (F.XF). Therefore, P.XP / (F.XF) = (XF – XW) / XF + P.XW / (F.XF). Subtracting P.XW / (F.XF) from both sides yields: P.XP / (F.XF) – P.XW / (F.XF) = (XF – XW) / XF. Thus, P/F × (XP – XW) = (XF – XW) / XF, and consequently P/F = (XF – XW) / (XP – XW). Substituting this value into the original equation gives: η = XP × (XF – XW) / 100%