| 摘要 |
The present invention relates to a pressure swing adsorption process for direct reduction of iron wherein a portion of spent reducing gas withdrawn from the direct reduction reactor is subjected to a PSA process for the removal of carbon dioxide from the spent reducing gas. An improved CO2-rejection method using an external natural gas purge stream after depressurization and before the product purge step is described. The PSA process comprises an external purge step with a non-adsorbable gas, which surprisingly reduces the adsorbent regeneration requirements to maintain the selective adsorption of carbon dioxide from the spent reducing gas. The external natural gas purge results in a cleaner bed before the start of each adsorption cycle. Consequently, significantly more CO2 can be rejected and/or higher hydrogen and CO recoveries can be attained. The external purge stream is fully integrated into the DRI production scheme.
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