Application: Modern hydrogen (H2) plants use a pressure swing adsorption (PSA) technology to recover H2 from shifted syngas. PSAs recover between 75% to 90+% of the total H2 in syngas. The remaining H2 balance is not recovered; thus is devalued as fuel gas. In response to growing concerns regarding greenhouse gas emissions, carbon dioxide (CO2) recovery is garnering greater attention. Fluor’s CO2LDSep is a patented process that consists of H2 and CO2 purification and recovery from a H2 plant’s PSA tailgas.
The tailgas from the PSA unit, in the existing H2 plant, enters the CO2LDSep plant and is compressed in the feedgas compressor (1). It is then dried (2), further compressed (3), cooled and expanded (4). The compression/expansion services may be accomplished in a single integrally geared package. A portion of the CO2 is removed through liquefaction. Supplemental refrigeration may be used, but is not required in most cases.
If food-grade CO2 production is desired, the liquid CO2 can be purified in a stripper (5) to a purity of 99.99 wt%. The CO2 is available as a pumpable liquid, which allows for low energy consumption when high product pressures are desired for enhanced oil recovery (EOR).
The H2-enriched gas leaving the CO2LDSep unit is sent to the H2 recovery PSA (6), where H2 of 99.9 vol% is separated from CO2, methane and other impurities. The tailgas stream from the new H2 recovery PSA along with the overhead from the stripper, if applicable, is routed to the reformer furnace where it is blended with the natural gas fuel and combusted.
Operating conditions: Typical PSA tailgas concentrations are 45% to 55% CO2 and 24% to 26% H2.
Licensor: Fluor Enterprises, Inc.
