Return to the process flow of the fuel processing system
In case the fuel gas contains sulfur compounds, the performance of the fuel processing system decreases; for this reason, the desulfurizer removes the sulfur components.
Desulfurization can be performed in three different methods described below:
Conventional desulfurization by means of the hydrogenation reaction｜
normal temperature desulfurization｜
Osaka Gas’ unique ultra-high-level desulfurization technology｜
Conventional desulfurization by means of hydrogenation reaction
||A sulfur compound reacts with hydrogen on catalyst (Ni-Mo-based; Co-Mo-based) to be converted into hydrogen sulfide (at 250˚C to 400˚C).
||Hydrogen sulfide is taken into zinc oxide to be removed (350˚C to 400˚C)
- A method generally adopted in hydrogen production plants
- Have to wait until the temperature of the hydrogenation catalyst layer rises.
- Sulfur content cannot be removed below 0.1ppm.
Normal temperature desulfurization
Sulfur compound is removed with an adsorbent like zeolite (at room temperature)
- Operating at room temperature allows a simple system configuration.
- With sulfur compound being adsorbed simply on the surface of the desulfurizer, a large amount of adsorbent are required for longer operation.
- Fluctuations in the conditions, such as temperature, pressure, and fuel gas will cause the adsorbed sulfur compound to be released.
Osaka Gas’ unique ultra-high-level desulfurization technology
Ultra-high-level desulfurization has both features of a hydrogenation desulfurization and normal temperature desulfurization.
- This technology allows operation at room temperatures; for this reason, it is not necessary to wait for the temperature of the desulfuriser to rise. (The desulfuriser is normally used at a temperature of about 250˚C in practice.)
- On account of its extremely strong affinity with sulfur, sulfer content is reduced to below a ppb (one thousandth of a ppm) level
- Only one liter of ultra-high-level desulfuriser is enough to operate a 1-kW PEFC system for 90,000 hours.
- The adsorption capability is not affected by humidity.
- COS, which cannot be removed by normal temperature desulfurization, can be removed easily by this method.
- Composed of inexpensive materials excluding noble metals; this method makes it possible to reduce costs.