Autothermal reforming syngas

Figure 9.11. Feed-side CO and C02 mole fraction profiles along the length of membrane reactor for autothermal reforming syngas. (Reprinted with permission from Huang et al.,6 Copyright 2005 Elsevier.)...

Figure 9.17. Effect of inlet feed temperature on required membrane area for autothermal reforming syngas.

For the autothermal reforming syngas, the membrane reactor could enhance H2 concentration from 45.30 to 54.95% on the dry basis, that is, from 41 to 49.32% on the wet basis... 

Cavallaro, S. Freni, S., Syngas and electricity production by an integrated autothermal reforming molten carbonate fuel cell system. Journal of Power Sources 1998, 76,190-196. 

ATR(l) [Autothermal reforming] A process for making CO-enriched syngas. It combines partial oxidation with adiabatic steam-reforming. Developed in the late 1950s for ammonia and methanol synthesis. Further developed in the 1990s by Haldor Topsoe. 

CAR [Combined autothermal reforming] A "reforming process for making "syngas from light hydrocarbons, in which the heat is provided by partial oxidation in a section of the reactor. Developed by Uhde and commercialized at an oil refinery at Strazske, Slovakia, in 1991. 

In addition to SMR, other technologies are used for syngas production from natural gas that involve addition of oxygen or air. The catalytic partial oxidation (CPO) reaction is given in Reaction (3) and in autothermal reforming (ATR) this reaction is combined with Reactions (1) and (2). 

Natural gas is reacted with steam on an Ni-based catalyst in a primary reformer to produce syngas at a residence time of several seconds, with an H2 CO ratio of 3 according to reaction (9.1). Reformed gas is obtained at about 930 °C and pressures of 15-30 bar. The CH4 conversion is typically 90-92% and the composition of the primary reformer outlet stream approaches that predicted by thermodynamic equilibrium for a CH4 H20 = 1 3 feed. A secondary autothermal reformer is placed just at the exit of the primary reformer in which the unconverted CH4 is reacted with O2 at the top of a refractory lined tube. The mixture is then equilibrated on an Ni catalyst located below the oxidation zone [21]. The main limit of the SR reaction is thermodynamics, which determines very high conversions only at temperatures above 900 °C. The catalyst activity is important but not decisive, with the heat transfer coefficient of the internal tube wall being the rate-limiting parameter [19, 20]. 

It is difficult to remove the last traces of CH4 in conventional steam reforming, and the reactions are fairly slow. Therefore, modem syngas plants frequently employ autothermal reforming, in which the major reaction is... 

The ATR (Autothermal Reforming) process makes CO-enriched syngas. It combines partial oxidation with adiabatic steam-reforming and is a cost-effective option when oxygen or enriched air is available. It was developed in the late 1950 s for ammonia and methanol synthesis, and then further developed in the 1990 s by Haldor Topspe2. The difference between Steam Methane Reforming (SMR) and ATR is in how heat is provided to activate the endothermic steam reforming reaction. In SMR, the catalyst is contained in tubes that are heated by an external burner. 

Fig. 1.20. Autothermal syngas generation by combining simultaneous autothermal reforming in an air/oxygen-fired fixed-bed reactor (ATR) and steam reforming in a gas-heated tubular fixed-bed reactor (GHR) [32, 33].

---