Reforming temperature

Fig. 4 Variations of methanol consumption flux along the channel length with increasing the reformer temperature = 1 bar, W/F = 6.72 kg-s/mol)...

Fig. 4 shows the evolution of temperature in the methanol steam reformer combined with a combustion plate equipped with a gas distributor. In this case hydrogen was used as a fuel for start-up at room temperature. As the reformer temperature reached near 300°C in about 5 min, methanol/water vapor was introduced to the reformer. It can be clearly seen that temperature within the reformer became relatively uniform after 25 min of operation. 

Reforming and Sulfur Removal - A better thermal match exists with existing reforming and sulfur removal processes. However, it should be noted the optimal nominal reformer temperature depends on the composition of the fuel. 

Notably, a strongly acidic catalyst or high reforming temperatures favor methane formation via DME decomposition (Equation 6.21). DME decomposition is generally suppressed in the presence of water. 

Even the process of experimental setup and measurement can be an issue. In a fixed bed laboratory reactor at reforming temperatures (near 800°C), the following sequence of reactions is thought to take place. Very near the... 

These results show that each of the carbon-forming reactions is thermodynamically favorable at typical reforming temperatures. The reactions of n-Ci6 and i-Cg are irreversible at these conditions. 

Table 3 shows that both reactions are highly favorable and irreversible at reforming temperatures. 

Thermodynamic calculations presented here are based on Gibbs free energy minimization and were carried out using HSC Chemistry. The equilibrium amount of each species that is formed is normalized on the basis of one mole of n-Ci6, a model compound for diesel fuel, fed to the reactor. Carbon formation is a function of both the S/C ratio and reforming temperature. Figure 17 shows the minimum amount of S/C ratio thermodynamically required for carbon-free SR of n-Ci6 at a given temperature. Carbon-free operation of n-Cig is thermodynamically possible above the curve. Higher temperatures and S/C ratios inhibit carbon formation. 

A typical reformer temperature profile for an inlet temperature of 783 K is shown in Fig. 5 for a three-reactor design. Only 15-20% of the total catalyst is used in the first reactor because of the rapid temperature decrease which results from naphthene dehydrogenation (Fig. 6). Note there is a 70 K temperature drop in this reactor. The activation energies are such that reaction rates are very low at the bottom of the first reactor. Thus, more catalyst in the first reactor would not provide additional conversion. 

Sinfelt and associates (S6) for a 0.3% platinum on alumina catalyst. At these temperatures diffusional effects are much less important than at the usual reforming temperatures. Over the range of methylcyclohexane and hydrogen partial pressures investigated, 0.07 to 2.2 atm. and 1.1 to 4.1 atm., respectively, the reaction was found to be zero order with respect to hydrogen and nearly zero order with respect to methylcyclohexane (Table III). The kinetic data were found to obey a rate law of the form... 

For hydrocarbon steam reforming, 95% conversion was achieved at GHSV values between 36 000 and 144 000 h 1 at very low reforming temperatures between 450 and 600 °C. Synthetic, sulfur free diesel was processed at a GHSV of 144 000 fT1 and an S/C ratio of 3 at a 530 °C reaction temperature. More than 90% conversion was achieved for almost 10 h duration. On the other hand, methanol reforming was performed at very high reaction temperature between 350 and 425 °C. 

HR where the reforming temperature equals that of the cell. 

Integration of SMR reaction and products (H2 or C02) separation steps to shift the equilibrium and enhance the reaction rate in the forward direction. This also lowers the reforming temperature to achieve the same conversion level. 

ATR reformer temperatures are in the range of 900-1150 °C, and the reformers with pressure between 1 and 80 bar have been designed and built so far. The ATR reactor is more compact than a steam reformer but larger than a POX unit. The main advantage of the ATR process is that it will produce a syngas with very favorable H2-to-CO ratio for downstream usage in chemical synthesis. The ratio should be 2 for Fischer-Tropsch liquids or methanol synthesis. 

Carbon formation limited by precious metal steam reforming catalysts, high steam-to-carbon (S/C) ratio (1.3), and high reforming temperature (>725°C)... 

Figure 2 TPO profiles for Pt-Re-S/AfO, coked in a commercial reformer. Temperature...

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