Reformer outlet

The reformer outlet composition is deterrnined by an approach to the simultaneous equiUbria of reactions 3 and 4, where m = 2n + 2 represents the paraffinic nature of natural gas. The stoichiometry of the reformed gas can be conveniently characterized by the ratio R, where... 

A promoted nickel type catalyst contained in the reactor tubes is used at temperature and pressure ranges of 700-800°C and 30-50 atmospheres, respectively. The reforming reaction is equilibrium limited. It is favored at high temperatures, low pressures, and a high steam to carbon ratio. These conditions minimize methane slip at the reformer outlet and yield an equilibrium mixture that is rich in hydrogen. ... 

Fig. 4. Reformer outlet profile with reactant feed rate change by 10% at 1 sec.

Fig. 6 shows the evolution of the CO concentration after the introduction of the methanol/water mixture to the reformer, indicating a CO spike at the initial stage of operation. CO concentration of up to 2% (dry basis) was observed at the reformer outlet by gas chromatography, but it was reduced to 0.6% in 20 min as shown in Fig. 6. CO concentration at the outlet of the PROX reactor operating at an 02 CO ratio of 1, increased rapidly to 1 lOOppm...

A 960 516 331 2.28 26 1.5 NPS Schedule 80 nozzle was broken off a catalytic reformer outlet line during a shut down. Metallography indicated surface decarburization and intergranular cracking with bubbles. Cr content was 1.09 percent. 

When combustion air preheat is used, the air preheat unit may replace the boiler feed water coil. Flue gas exits this unit at about 300 degrees F. This provides a typical heat loss of 3% of the overall reformer efficiency. Steam is also made in a process steam generator which extracts heat from the reformer outlet process gas. The heat recovery unit and process steam generator normally have a common steam drum. 

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]. 

The base case conditions for the model are shown in Table 8.9, with the reformer outlet fuel composition shown in Table 8.10. The conditions are similar to those given for a 260 kW thermodynamic model by Campanari [21], with a 207 kW output for the fuel cell and 53 kW for the turbine alternator. There is a considerable difference between the alternator power in this model (130 kW) and Campanari s (53 kW). The model in this study uses external heating for the reformer so that its heat load is not included in the analysis, which accounts for the discrepancy. 

After the reformer outlet, air was added again before the reformate entered the PrOx zone. The pressure drop of the whole coupled evaporator/reformer/PrOx reactor was limited to 200 mbar at full load. The whole IFP had a mass of 1.8 kg for a volume of 0.5 dm3. At a reaction temperature of 280 °C, a methanol feed of 15 mol h 1 and a water/methanol ratio of 1, almost complete (> 99%) conversion... 

For reformer outlet manifolds the normal metallurgy choice is a wrought type of Alloy 800 H. It has sufficient ductility and thermal-shock resistance during startup and shutdown. The cast version of Alloy 800 H provides a cost-effective, alternate material with a higher creep-rupture strength, low tendency for embrittlement and good ductility. Hot reformed-gas transfer lines are usually refractory-lined with an interior of Alloy 800 sheathing88. 

For reformer outlet manifolds, the normal metallurgy choice is a wrought type of Alloy 800 H. Hot reformed-gas transfer lines are usually refractory-lined with an interior of Alloy 800 sheathing.88... 

Increased Process Air Supply to the Secondary Reformer. Decreased heat supply in the primary reformer means that increased internal firing is necessary to achieve approximately the same degree of total reforming. A somewhat higher methane slip (and thus a lower secondary reformer outlet temperature) is acceptable and preferable in this type of process. This is because methane is removed in the final purification.53... 

The microalloy tubes allow increased flux rates and higher reformer outlet temperatures. This in turn can make it possible to reduce the steam-to-carbon ratio while the hydrogen purity remains the same.86... 

Assuming a small-scale PSA system operating at reformer outlet pressure. 

Raw syngas from the primary reformer furnace is a mixture of hydrogen, carbon monoxide, carbon dioxide and unreacted methane. A typical reformer outlet gas composition is shown in Table 1. This composition corresponds to a furnace outlet temperature of 1620 F, outlet pressure of 340 psig and a S/C ratio of 4.0 [1]. 

Hwang et al. [68] reported silica-modified Pt/Ce02 catalysts for the WGSR. They evaluated catalysts at 270 °C in a reformer outlet composition. The order... 

Membrane integration into the reaction environment ensures a first substantial hydrogen separation step (up to 90% of the hydrogen produced can be removed) as for CO2 separation, because of the higher carbon dioxide partial pressure in the reformer outlet stream, due to the hydrogen removal, physical separation methods could be used to separate CO2 rather than the chemical adsorption in mono-diethanol ammine (MDEA). 

C, and the temperature of the tube wall may be 900°-950°C or more. This high temperature and the high pressure constitute severe conditions that require expensive materials of construction at the reformer outlet and careful design and operation. The heat in the combustion gas leaving the reformer is used successively to produce steam, to preheat the incoming feedstock-steam mixture, and, where fuel economy is important, to preheat combustion air. 

The reforming exchanger concept totally eliminates the furnace and uses a hot secondary reformer outlet as its heat source. Surplus air over the stoichiometric demand or oxygen-enriched air in the secondary reformer is required to balance the heat demand for the primary reforming reaction. Chiyoda proposed this concept in 1984 [26,271 however, ICI was the first one. to comr mercialize a reformer exchanger called the Gas Heat Reformer (GHR) as part of their Leading Concept Ammonia (LCA) process. The GHR is discussed further under the LCA process section. 

A variety of syngas compositions, ready to be fed to the membrane modules, can be produced by acting on the steam/carbon ratio and on the reformer outlet temperature through the variation of the firing of two hot gas generators. This makes it possible to study the role played by partial pressures of the main components in separation performance. The effect of temperature on membrane permeance at fixed reformer working conditions may be studied by varying the temperature set point of two air coolers placed at the inlet of the membrane modules. 

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