Development of a Pressure Swing Adsorption Cycle for Producing High Purity CO2 from Dilute Feed Streams. Part I: Feasibility Study

Abstract

Simulations of a 3-bed 9-step pressure swing adsorption (PSA) cycle were carried out to study the enrichment and recovery of 0.4 vol % CO2 from dry air using 13X zeolite with the feed pressure and flow rate fixed at 1 atm and 570 SLPM. The goal was to produce 97 vol % CO2 at greater than 62% CO2 recovery, less than 1 kW vacuum pump power, and small volume. The PSA cycle step sequence consisted of feed (F), idle (I), heavy reflux (HR), cocurrent equalization down (EqD), forced cocurrent depressurization (CoD), countercurrent depressurization (CnD), light reflux (LR), countercurrent equalization up (EqU), and light product pressurization (LPP). A parametric study revealed the following effects on the PSA process performance. Increases in the HR = LR = F step time (thus cycle time) caused significant increases in the CO2 purity and vacuum pump power, while the CO2 recovery exhibited a modest maximum. Increases in the LR ratio caused significant increases in both the CO2 recovery and power but only a modest i...