Hydrogen recovery and purification or rejection from various refining, petrochemical and chemical process gas streams.…
Hydrogen (Polybed PSA) Process by UOP LLC
Application: Production of any purity hydrogen, typically 90% to +99.9999 mole%. Impurities efficiently
removed include: N2, CO, CH4, CO2, H2O, Ar, O2, C2–C8+, CH3OH, NH3, H2S and organic sulfur compounds.
The technology can also be used to: purify CH4, CO2, He, N2 and Cl; remove CO2; adjust synthesis-
gas stream composition ratios and separate nitrogen
Feed: Steam reformer (at any point after the reformer), catalytic reformer net gas, other refinery purge streams, gasification offgases, ammonia plant purge gases (before or after the NH3 waterwash), demethanizer or other ethylene plant offgases, partial oxidation gases, styrene plant offgases, methanol plant purge gases, coke-oven gas, cryogenic purification offgases or other H2 sources. Feed pressures up to 1,000 psig have been commercially demonstrated.
Product: Recovery of H2 varies between 60% and 90%, depending on composition, pressure levels and
product requirements. Typical temperatures are 60°F to 120°F. Purity can be +99.9999 mole%.
Purification is based on advanced pressure swing adsorption (PSA) technology. Purified H2 is delivered at essentially feed pressure, and impurities are removed at a lower pressure. Polybed PSA units contain 4 to +16 adsorber vessels. One or more vessels are on the adsorption step, while the others are in various stages of regeneration. Single-train Polybed PSA units can have product capacities over 200 million scfd.
All systems use advanced proprietary adsorbents and patented void-gas recovery techniques to provide maximum product recovery. Other than entrained liquid removal, no feed pretreatment is required. In addition, all impurities are removed in a single step, and purities exceeding 90% are obtained irrespective of impurities. Many units presently produce streams with less than one ppmv impurity from feed concentrations of +40 mole%.
Operation is automatic with pushbutton startup and shutdown. After startup, the unit will produce H2
in two to four hours. Onstream factors in excess of 99.8% relative to unplanned shutdowns are typical.
Turndown capability is typically 50% but can be even lower where required. The units are built compactly with plot plans ranging from 12 x 25 ft to 60 x 120 ft. Units are skid-mounted and modular to minimize installation costs. Material for piping and vessels is carbon steel. Control can be via a local or remote-mounted control panel or by integration into the refinery’s computer control system. Units are designed for outdoor, unattended operation and require no utilities other than small quantities of instrument air and power for instrumentation.
Licensor: UOP LLC
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