Backfill cycle of a layered bed H(2)PSA process

H Ahn, CH Lee, B Seo, J Yang, K Baek

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The backfill cycle of two-bed PSA process using activated carbon beds, zeolite 5A beds, and layered beds was studied experimentally and theoretically to recover high purity H-2 from coke oven gas. In a layered bed PSA, a comparison was made between two PSA processes with/without a backfill step before the feed pressurization step. Since the backfill step made the adsorption bed rich in H-2 and this led to a rather steep concentration wave front at the feed pressurization step, incorporating a backfill step resulted in an increase in product purity with a decrease in recovery. Each step of the single-adsorbent and layered bed PSA processes with a backfill step was simulated with a dynamic model incorporating mass, energy, and momentum balances. The model agreed well with the experimental results in predicting the product H-2 purity and recovery, thus giving a basic understanding of the bed dynamics of a backfill cycle. While the concentration and temperature profiles of a layered bed in each step showed characteristic behavior of each adsorbent in each layer, the product purity of a layered bed was not between the limits of two single-adsorbent bed processes. The concentration profiles predicted by simulation showed that CO and N-2 played an important role in obtaining high H-2 purity.

Original languageEnglish
Pages (from-to)419-433
Number of pages15
Issue number4
Publication statusPublished - Oct 1999


  • backfill step
  • single-adsorbent bed
  • layered bed
  • coke oven gas
  • H(2)PSA

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