Synthesis gas production for GTL applications: Thermodynamic equilibrium approach and potential for carbon formation in a catalytic partial oxidation pre-reformer

• A thermodynamic approach to methane and natural gas reforming (CPO and ATR reactors) for GTL applications has been used.
• Syngas production (CPO + ATR) requires an appropriate combination of operating variables in order to obtain a H2/CO = 2.0.
• Risk for carbon in a CPO pre-reformer can be reduced or even eliminated by proper manipulation of operating variables.

The present work is focused on synthesis gas production for Gas to Liquids (GTL) applications. A thermodynamic equilibrium approach has been chosen in order to address the methane reforming processes in presence of steam and oxygen (i.e. autothermal reforming “ATR” and catalytic partial oxidation “CPO”). The effect of operational variables on the performance of the reforming units has been analyzed at conditions typical for GTL processes. Also, the performance of a synthesis gas generation unit (SGU) comprising a CPO pre-reformer followed by an ATR reactor has been investigated. The potential for carbon formation in the CPO pre-reformer has been evaluated by applying the “equilibrated gas principle”. Our results show that synthesis gas production can be strongly influenced by changes in operating variables such as the steam-to-carbon (S/C) and the oxygen-to-carbon (O2/C) ratios, recycled gas (tail gas) compositions, and operating pressures and temperatures; however, effective operation of the SGU (CPO + ATR) requires an correct combination of these variables in order to accomplish the synthesis gas requirements of the Fischer–Tropsch synthesis. Likewise, it is shown that the risk of carbon formation in the CPO reactor can be reduced or even eliminated by a proper manipulation and combination of such variables.