India
South Africa
Japan
Methanol Production
Feedstock NG is desulfurized prior to steam reforming similarly to Hydrogen production. The desulfurized NG is conveyed to steam reformer ("SMR Alone") with Reactions (1), (3) and (4) in the catalyst bed or optionally to the steam reformer in a combined reforming system ("CR") with the same Reaction (1), (3) and (4) as the primary reformer followed by Reaction (5) in the combustion zone and Reaction (3) and (4) in the catalyst bed of oxygen blown ATR as the secondary reformer. The amount of oxygen is controlled to realize the R-value defined below in the make-up syngas to synloop to be 2.05, a little bit H2 richer than the stoichiometric value to mainain driving force of reaction against chemical equilibrium.
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R ≡ ( [H2 mol%] - [CO2 mol%]) / ( [CO mol%] + [CO2 mol%])
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The defined R-value is a substantial [H2] /[CO] ratio of syngas stream, for which 2.0 is the stoichiometric value of the MeOH synthesis reaction (M1) by CO below considering an influence of CO2 amount in the competing synthesis reaction (M2) by CO2.
Methanol Synthesis
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CO + 2 H2 = CH3OH ΔH = -90.8 MJ/kmol (M1)
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CO2 + 3 H2 = CH3OH + H2O ΔH = -49.6 MJ/kmol (M2)
Residue methane is just an inert in MeOH synloop and is purged out from the loop for the use as fuel in the steam reformer. See the figures below as for the difference between SMR Alone configuration vs. CR configuration in the syngas generation section for methanol production as well as the concept of MeOH synloop.
