Can someone explain why CO concentration increases at the outlet of 2nd reformer while CO2 concentration decreases when compared to Primary reformer outlet. Ours is 2200MTPD Topsoe Plant.
PRO SRO
CO-8.88 13.56
CO2-9.63 6.42
CH4-15.33 0.21
Composition in vol%
Hi,
Reason is the much higher temperature (1000 deg vs 800 deg). The water gas shift reaction favours CO at higher temperature. That fact explains the two stage shift section where the final step is at low (200 deg C) temperature.
1. At 900-1000C pyrolysis of methane occur which is form carbon & that carbon in presence of limited oxygen convert to carbon monoxide.
2. Due to limited supply of oxygen, methane also get partially oxidize to carbon monoxide.
CO conc increase because CH4 reforming takes place in secondary reformer. When primary reformer gas comes in contact with air in secondary reformer then hydrogen reacts with the oxygen and forms H2O which acts as steam for remaining methane reforming and concentration of CO increases. Moreover, some methane also go into auto combustion and forms CO2.
Hopefully, you got the proper answer. Thank you!
Zeeshan
This reply was modified 3 months, 1 week ago by Shoaib Zeeshan.