Hydrogen production from F-T synthesis exhaust gases
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What processes are mainly used to produce high-purity hydrogen from F-T synthesis exhaust gases? Are technologies such as pressure swing adsorption, membrane separation, and cryogenic separation useful?
This post was last edited by *aojungnft on 2011-10-17 at 17:33. Although there aren’t many projects in operation at present, when it comes to separating H2 from exhaust gases, pressure swing adsorption is the first method that comes to mind; it is also used in many coal-to-oil process designs. This technology is relatively mature, with strong practical applicability and ease of use. Membrane separation is not easily used. Deep cryogenics requires a separate deep cryogenics unit and distillation tower, similar to deep cryogenic air separation. The issue of membrane separation versus cryogenic methods: although large-scale installations currently tend to use cryogenic techniques, which also offer advantages in terms of energy consumption, at least so far, in the oil processing projects I’ve seen, cryogenic methods have not been used for hydrogen separation.
Pressure swing adsorption! Shenhua’s indirect liquefaction uses pressure swing adsorption~
This post was last edited by juna8908 on 2012-3-21 at 10:52. The PSA technology can be used to recover H2 from F-T synthesis exhaust gases; the process is as follows: F-T synthesis exhaust gases → CO conversion → PSA separation of H2. When the CO2 content is high: F-T synthesis exhaust gases → CO conversion → CO2 removal → PSA separation of H2. Both CO and H2 in F-T synthesis off-gases can be used as effective sources for H2 recovery; CO can be converted into hydrogen, thereby increasing the H2 content in the off-gases and improving the yield of H2. Generally, it is feasible to use PSA for H2 recovery when the H2 content in the off-gases is above 40%, and the purity of the resulting hydrogen can reach 99.99%. The process of Yitai’s 160,000-ton coal-to-oil plant involves using PSA to recover H2 from the exhaust gases and utilizing it for product purification. The recovery of useful gases from F-T synthesis exhaust gases is relatively cost-effective using PSA technology, as the sulfur content in the exhaust gases is below 0.1 ppm. Employing PSA technology allows for savings in investment costs associated with desulfurization equipment; however, it is necessary to treat water and light hydrocarbons. Modern PSA technologies in China include such treatment facilities, and the associated investment costs are not high.