Akademik Veri Yönetim Sistemi
Industrial and Engineering Chemistry Research, cilt.60, sa.27, ss.9928-9939, 2021 (SCI-Expanded)
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 ReLP,B, the purity of A in the heavy product y¯ HP, and the final pressures of the BB and BTB equalization steps were derived. The effects of the relative size of the equalization tanks ψ (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 ?CnD,o was important. With increasing ψ or n, ?CnD,o always decreased and both y¯ HP and ReLP,B always increased, and when the BTB and BB configurations achieved the same ?CnD,o, their PSA cycle performances were identical. Increasing ψ at constant n caused the BTB ?CnD,o to approach that of the BB ?CnD,o, and they became equal for only very large tanks (e.g., ψ = 500). However, increasing nBTB at constant nBB and ψ caused the BTB ?CnD,o to be even lower than the BB ?CnD,o for some reasonable ψ. Therefore, instead of using larger tanks in BTB to achieve the same BB performance, it was better to increase nBTB at a reasonable ψ to keep the tank volume smaller. For the same performance (i.e., the same ?CnD,o), the total volume of all tanks (i.e., nψ) decreased with increasing n, and in the limit of nBTB → ∞, nψ approached a minimum total tank volume equal to nBB. 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.