Tubular reformer

Nishino, T., Iwai, H. and Suzuki, K. (2006) Comprehensive numerical modeling and analysis of a cell-based indirect internal reforming tubular SOFC, Journal of Fuel Cell Science and Technology 3, 33 14. 

The Primary Reformer is a steam-hydrocarbon reforming tubular furnace that is typically externally fired at 25 to 35 bar and 780°C to 820°C on the process side. The reformer tubes function under an external heat flux of 75,000 W/m2 and are subject to carburization, oxidation, over-heating, stress-corrosion cracking (SCC), sulfidation and thermal cycling. Previously SS 304, SS 310 and SS 347 were used as tube materials. However these materials developed cracks that very frequently led to premature tube failures (see Table 5.10)88. 

The primary reformer is a steam-hydrocarbon reforming tubular furnace that is typically externally fired at 25 to 35 bar and 780°C to 820°C on the process side. From the 1950s through the 1960s SS 304, SS 310, SS 347,... 

Tubular Fixed-Bed Reactors. Bundles of downflow reactor tubes filled with catalyst and surrounded by heat-transfer media are tubular fixed-bed reactors. Such reactors are used most notably in steam reforming and phthaUc anhydride manufacture. Steam reforming is the reaction of light hydrocarbons, preferably natural gas or naphthas, with steam over a nickel-supported catalyst to form synthesis gas, which is primarily and CO with some CO2 and CH. Additional conversion to the primary products can be obtained by iron oxide-catalyzed water gas shift reactions, but these are carried out ia large-diameter, fixed-bed reactors rather than ia small-diameter tubes (65). The physical arrangement of a multitubular steam reformer ia a box-shaped furnace has been described (1). 

Traditionally, the steam reforming reactor has a tubular design in which vertical tubes, loaded with catalyst, are surrounded by furnaces to supply the heat required for the strongly endothermic process, see Fig. 8.2. Combustion of natural gas supplies the heat to the tubes. 

Use of a special catalyst in the tubular reformer, and a special start-up system... 

Schematics of the reformer section of combined reforming of NG. 1 = Fired tubular reformer, 2 = furnace, and 3 = autothermal reformer.

Sanchez, D., Chacartegui, R., Munoz, A. and Sanchez, T. (2006) Thermal and electrochemical model of internal reforming solid oxide fuel cells with tubular geometry, Journal of Power Sources 160(2), 1074-1087. 

Other manufacturers have proposed different solutions. The cell manufactured by Acumentrics is similar to the Siemens Westinghouse tubular SOFC the differences mainly reside in the fuel flowing inside the cell without inlet pipe and in the tube having open ends. Reforming is internal to the tube. The Acumentrics cell operates in the same temperature range than the previously mentioned SOFCs, but... 

Stacks of tubular SOFCs may consist of numerous cells plus additional devices such as the reformers. In the case of Siemens CHP100 unit, currently installed in Torino,... 

Adiabatic with Intermediate Heat Transfer. Many tubular reactor systems use a series of adiabatic reactors with heating or cooling between the reactor vessels. For example, naphtha reforming has endothermic reactions of removing hydrogen from saturated cyclical naphthene hydrocarbons to form aromatics. The process has multiple adiabatic reactors with fired furnaces between the reactors to heat the material back up to the required reactor inlet temperature. 

Figure 1 Schematic representation of the temperature profile of a tubular steam reformer as a function of time on stream...

Epstein, M., et al. (1996), Solar Experiments with a Tubular Reformer , Proc. 8th Int. Symp. on Solar Thermal Concentrating Technologies, M. Becker and M. Bohmer, (Eds.), Cologne, Germany, 6-11 October. 

Steam reforming refers to the endothermic, catalytic conversion of light hydrocarbons (methane to gasoline) in the presence of steam [see Eq. (5.1)]. The reforming reaction takes place across a nickel catalyst that is packed in tubes in an externally-fired, tubular furnace (the Primary Reformer). The lined chamber reactor is called the secondary reformer , and this is where hot process air is added to introduce nitrogen into the process. Typical reaction conditions in the Primary Reformer are 700°C to 830°C and 15 to 40 bar46. 

BP and Kvaemer Process were finalizing the demonstration of their Compact Reformer Technology in 2001. This technology involves the integration of combustion, heat transfer and catalytic reaction within a simple tubular module. This reformer is about 30% lighter (in weight) than a conventional reformer of equivalent capacity90. 

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].

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