Equilibrium Theory Analysis of Pressure Equalization Steps in Pressure Swing Adsorption

Fakhari-Kisomi B., Erden L., Ebner A. D., Ritter J. A.

INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, vol.60, no.27, pp.9928-9939, 2021 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 60 Issue: 27
  • Publication Date: 2021
  • Doi Number: 10.1021/acs.iecr.1c01144
  • Journal Name: INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Applied Science & Technology Source, Aqualine, Chemical Abstracts Core, Chimica, Compendex, Computer & Applied Sciences, zbMATH, DIALNET
  • Page Numbers: pp.9928-9939
  • Çanakkale Onsekiz Mart University Affiliated: No

Abstract

A binary, linear isotherm, isothermal equilibrium theory analysis of Skarstrom-type PSA cycles with bed-to-bed (BB) and bed-to-tank-to-bed (BTB) equalization steps was carried out with a binary gas mixture of A and B, with A more strongly adsorbed than B. For tractability, it was assumed that the gas produced from the light end of a bed contained only B and thus the recovery of A in the heavy product was 100%. Analytic expressions for the periodic state PSA cycle performances based on the recovery of B in the light product Re-LP,Re-B, the purity of A in the heavy product (y) over bar (HP), and the final pressures of the BB and BTB equalization steps were derived. The effects of the relative size of the equalization tanks Psi (varied from 0.1 to 500) and the number of equalization steps n (varied from 1 to 10) were studied. The initial pressure in the bed at the beginning of the countercurrent depressurization (CnD) step Pi(CnD, o) was important. With increasing. or n,Pi(CnD, o) always decreased and both yHP and ReLP, B always increased, and when the BTB and BB configurations achieved the same Pi C-nD,C-o, their PSA cycle performances were identical. Increasing Psi at constant n caused the BTB.CnD, o to approach that of the BB Pi Cn(D,o,) and they became equal for only very large tanks (e.g.,. = 500). However, increasing nBTB at constant n(BB) and caused the BTB Pi C-nD,C- o to be even lower than the BB Phi Cn(D, o) for some reasonable Psi. Therefore, instead of using larger tanks in BTB to achieve the same BB performance, it was better to increase n(BTB) at a reasonable. to keep the tank volume smaller. For the same performance (i.e., the same Pi(CnD,o)), the total volume of all tanks (i.e., n.) decreased with increasing n, and in the limit of nBTB -> infinity, n Psi approached a minimum total tank volume equal to n(BB). This result indicated a lower limit exists on the minimum total volume of tanks required to achieve the same performance as in the BB configuration.