Steam reformer vs dry reformer

[katchum]

Main Question or Discussion Point

Which one would you prefer?

Steam reformer:

CH4 + H2O -> CO + 3H2
CO + H2O -> CO2 + H2

Dry reformer:

CH4 + CO2 -> 2CO + 2H2


1) The SR uses steam injection, the DR doesn't have steam, which can be good.

2) The DR doesn't yield much H2 for a given amount of CH4... And the water shift reaction of the SR would even yield more H2. Minus point for the DR.

 

[PRDan4th]

It depends on what you are trying to make! SR and CO shift is the traditional way to make H2 (for use in oil refining or NH3 production). Both reactions are endothermic and therefore take heat to go. I have not seen the DR process, but I suspect it would require water to prevent carbon deposition. Most syn gas processes require a 2/1 H2/CO ratio for downstream chemistry. The two processes combined in the right mix could yield a 2/1 ratio. SR produces too much H2 and DR too little for methanol production downstream.

 

[katchum]

If you look at the steam reformer:

Would you want to add CO2 seeing that that would react with CH4, like in the DR?

And when we are talking about NH3 production, I think a SR would be the best way to do it as you need much H2? And N2 would only be added in a later stadium.

I don't understand: why would you need a 2/1 ratio H2/CO?