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Four-Bed Low Pressure CO2 VSA Process Without Depressurization Gas Recycling

IP.com Disclosure Number: IPCOM000019366D
Publication Date: 2003-Sep-12
Document File: 3 page(s) / 63K

Publishing Venue

The IP.com Prior Art Database

Abstract

Removal of CO2 from the reducing gas (mainly H2 and CO) fed to a direct reduced iron (DRI) process, such as the COREX SYMBOL 210 \f "Symbol" process, can be accomplished by adsorptive separation, e.g. a GEMINI-4 or GEMINI-5 process. The process described herein is a four bed system with six process steps. A schematic of the suggested cycle and process is given in Figures 1 and 2. A brief description of the six process steps is given below.

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Four-Bed Low Pressure CO2 VSA Process Without Depressurization Gas Recycling

Removal of CO2 from the reducing gas (mainly H2 and CO) fed to a direct reduced iron (DRI) process, such as the COREX process, can be accomplished by adsorptive separation, e.g. a GEMINI-4Ô or GEMINI-5Ô process. The process described herein is a four bed system with six process steps. A schematic of the suggested cycle and process is given in Figures 1 and 2. A brief description of the six process steps is given below.

         i. Feed - A mixture of strongly adsorbed and weakly adsorbed gases (for example H2, CO, and CO2 in the COREX offgas) enters the bottom of an adsorbent bed (e.g. 13X molecular sieve). The adsorbent selectively adsorbs the strongly adsorbed component (CO2 in the example) and the weakly adsorbed components (H2 and CO in the example) pass through the bed and exit the bed with very high purity. As the bed nears saturation with the strongly adsorbed component, the latter will begin to break through the bed indicating an end of the feed step.

         ii. Equalization - Following the feed step, the adsorbent bed is first depressurized. The depressurization gas is throttled through a valve and directed to another bed which just finishes evacuation. This step stops when the beds in connection are pressure-equalized.

         iii. Blowdown - At the end of the equalization step, the adsorbent bed is still above atmospheric pressure. The bed continues to depressurize by venting the gas to the atmosphere or flaring until the bed pressure is equal to the ambient.

         iv. Evacuation - The remaining strongly adsorbed gas still left on the adsorbent can be desorbed by evacuating the adsorbent bed to a sub-ambient pressure with a vacuum pump. A vacuum level as low as 80 torr may be needed to effectivel...