Reformer Design

The continual development of the steam reforming process ensured that this became the most practicable way to produce synthesis gas and ammonia on the large scale. A mixture of hydrocarbons and super-heated steam is passed through the reactor tubes that are packed with the nickel catalyst, and suspended in a furnace that operates at temperatures around 1000°C (Figs. 9.1 and 9.2). The steam reforming reaction is extremely endothermic and the heat of reaction must be supplied continually at a very high operating temperature. The catalyst must 

Low-pressure reformers were used in the early ammonia plants, partly because of the simple design and low production capacity and mainly because of the hmited physical properties of the stainless steel that was available at the time. The operating pressure could not be increased because the reactor tubes 

The hydrocarbon reforming reaction gives a mixture of carbon monoxide and water which is close to eqnihbrinm at the usnal operating conditions. The reaction between steam and the hydrocarbon gives a mixture of carbon monoxide and hydrogen that is close to thermodynamic eqnilibrium at the temperature and pressure of the reactor. 

The operating steam to hydrocarbon ratio, or steam ratio, must, however, be higher than the stoichiometric level to avoid carbon formation on the catalyst, by cracking reactions, and to provide enough steam to operate the water gas shift reaction later in the process. 

The presence of excess steam in the process gas to the reformer results in the formation of carbon dioxide by the water gas shift reaction. Thus the gas leaving the steam reformer also contains between 7 and 15% carbon dioxide  

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Natural Gas Reformer Design for Ammonia Plants," Part 1, Nitrogen 166, 24—29 (1987). 

Note Typically in reformer design, liquid hourly space velocity (LHSV) is defined as fresh liquid charge volumetric flow rate divided by catalyst volume. Catalyst volume includes the void fraction and is defined by WJpp( — e).]... 

High Efficiency Reformer Design. Maximum feedstock and combustion air preheat is used to balance steam generation with steam requirements. 

Proper integration of advanced reformer design with adsorption purification systems can reduce overall feed and fuel requirement below 400 Btu per standard cubic foot of hydrogen. 

The arrangement of burnes is the criterium by which reformer designs are normally classified. The different possibilities are shown in Figure 38 [421],... 

Key features are the high reforming pressure (up to 41 bar) to save compression energy, use of Uhde s proprietary reformer design [1084] with rigid connection of the reformer tubes to the outlet header, also well proven in many installations for hydrogen and methanol service. Steam to carbon ratio is around 3 and methane slip from the secondary reformer is about 0.6 mol % (dry basis). The temperature of the mixed feed was raised to 580 °C and that of the process air to 600 °C. Shift conversion and methanation have a standard configuration, and for C02 removal BASF s aMDEA process is preferred, with the possibility of other process options, too. Synthesis is performed at about 180 bar in Uhde s proprietary converter concept with two catalyst beds in the first pressure vessel and the third catalyst bed in the second vessel. 

Fig. 11.5. The Tops0e reformer design with tube and burner arrangement. Reprinted from Rostrup-Nielsen [10] with permission from Springer.

For reforming of methane, kinetics allow methane to decompose into carbon instead of reacting with steam even if thermodynamics predict no carbon formation. However, with proper reformer design, industrial operation at HgO/CH =... 

Natural gas reformer design for ammonia plants I. primary reformer design criteria, Nitrogen, 166 24—30 (1987). 

Natural gas reforming design for ammonia plants II secondary reformer design, Nitrogen, 167 31-36 (1987). 

Case 1 Conv. H2 plant Case la Conv. H2 plant w/carbon membrane Case 2 Reformer W/AI2O3 membrane Case 2 Reformer W/AI2O3 and carbon membrane Case 3 Conv. H2 plant w/Fuel cell Case 3 Conv. H2 plant w/Fuel cell and carbon membrane Case 4 Auto-reformer design... 

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