Effects of Nonisobaric and Isobaric Steps on O₂ Pressure Swing Adsorption for an Aerator

Abstract

The effects of nonisobaric and isobaric steps on a two-bed O 2 pressure swing adsorption (PSA) packed with zeolite 5A were investigated. In addition, the operating conditions in the O 2 PSA were studied to supply the various O 2 concentrations to the oxygen aerator efficiently. Because the velocity variation along the bed and the related Mass Transfer Zone (MTZ) shape at the isobaric and nonisobaric steps were affected by the diffusion rate, the concentration-dependent rate parameter in a modified linear driving force (LDF) model was evaluated from the Darken equation related to the loading ratio correlation isotherm model. The LDF coefficients had a significant effect on the prediction of the O 2 purity and recovery at the low flow rate region. However, the higher the feed flow rate, the lower the LDF parameter effect. It was also noted that the effects of each step time in the isobaric and nonisobaric steps on the PSA performance were subtle in the O 2 purity and recovery except for the blowdown step. Also, there was the optimum step time to maximize the O 2 purity and recovery in the adsorption and pressurization steps, while the increase of O 2 purity and recovery with the pressurization equalization step time showed asymptotic curvature. The idle time at the pressurization step had a negative effect on the PSA performance, while the short idle time at the pressure equalization step led to improved product purity. However, it was negligible for the effect of the idle time at the blowdown step on the PSA performance. The successive variation between high and low P/F ratios caused the continuous variation of O 2 purity and recovery to nearly the same extent as the results under each constant P/F ratio condition. Therefore, to save the operating cost of the oxygen aerator system, the desired oxygen concentration for the aerator can be supplied simply by controlling the feed rate or purge rate.

Three‐bed PVSA process for high‐purity O2 generation from ambient air

“…The pressure history during a PSA experiment at the feed or bed end was fitted by polynomials and used as a boundary condition for the overall mass balance 21…”

Simulation study of pressure swing adsorption to purify helium using zeolite 13X

“…An experimental and simulation study of a PSA unit which is running a traditional Skarstrom cycle and a Skarstrom cycle with co-current equalization owing to separate oxygen from air using a 5A zeolite has been proposed by Mendes et al [11] in 2001. Moreover, a small-scale two-bed six-step PSA process using zeolite 13X was performed by Jee et al [27][28][29][30] in order to provide oxygen-enriched air. They showed that there is a strong effect of feed flow rate on O2 purity.…”

“…The impact of temperature variations in gas phase during adsorption as a function of time is illustrated in Figure 2(c). It is obviously seen that there is a relatively high accuracy in the simulation of experimental data [27] .…”

Water and mercaptan adsorption on 13X zeolite in natural gas purification process

“…The assumption of neglecting radial gradient was widely accepted by numerous adsorption studies like Rota and Wankat [9], Jee et al [10], and Kim et al [11].…”