Chemical Engineering Spot: Hydrogen (H2) Generation Technique

Natural Gas (NG) from header is divided into two parts-

One goes to reformer burner as fuel and mixes with air from FD fan.
Another goes to NG compressor.

Desulfurizer:

Compressed NG goes to desulfurizer where sulfur is removed with the presence of Manganese Oxide (MnO) and Zinc Oxide (ZnO) catalysts. The following reactions are performed into desulfurizer.

COS + MnO → MnS + CO₂
H₂S + MnO → MnS + H₂O
H₂S + ZnO → ZnS + H₂O

Reformer:

After desulfurization, natural gas mixes with steam by maintaining a certain steam carbon ratio (between 3.5 to 4.5). Then mixed NG and steam go to the reformer tubes through the top side and go out from the bottom side of the reformer tubes and enter the tube side of Waste Heat Boiler (Steam is generated here).

Air from FD fan, Fuel Gas and off gas go to the top side of the reformer burner (outside of reformer tube) and go out from bottom side of reformer to atmosphere through ID fan.

The following reactions are performed into the tubes of reformer with the presence of Ni Catalyst-

CH₄ + H₂O→ CO + 3H₂
CO + H₂O →CO₂ + H₂

Shift Converter:

Reformed gas then goes to shift converter. Here CO is converted to CO₂ with the presence of Ferric Oxide Catalyst-

CO + H₂O → CO₂ + H₂

After shift converter the Process Gas goes to the series of heat exchangers.

Pressure Sewing Adsorption (PSA):

Finally process gas goes to the PSA unit from where 99.99 % purified Hydrogen (H₂) is generated.

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