Reformer side-fired

Steam reformers are used industrially to produce syngas, i.e., synthetic gas formed of CO, CO2, 11-2, and/or hydrogen. In this section we present models for both top-fired and side-fired industrial steam reformers by using three different diffusion-reaction models for the catalyst pellet. The dusty gas model gives the simplest effective method to describe the intermediate region of diffusion and reaction in the reformer, where all modes of transport are significant. This model can predict the behavior of the catalyst pellet in difficult circumstances. Two simplified models (A) and (B) can also be used, as well as a kinetic model for both steam reforming and methanation. The results obtained for these models are compared with industrial results near the thermodynamic equilibrium as well as far from it. 

Industrial steam reformers are usually fixed-bed reactors. Their performance is strongly affected by the heat transfer from the furnace to the catalyst tubes. We will model both top-fired and side-fired configurations. 

Plant (2) is a side-fired steam reformer with the following construction and operating data. 

Side-fired reformer (2) construction data and operating conditions ... 

Today contractors and licensors use sophisticated computerized mathematical models which take into account the many variables involved in the physical, chemical, geometrical and mechanical properties of the system. ICI, for example, was one of the first to develop a very versatile and effective model of the primary reformer. The program REFORM [361], [430], [439] can simulate all major types of reformers (see below) top-fired, side-fired, terraced-wall, concentric round configurations, the exchanger reformers (GHR, for example), and so on. The program is based on reaction kinetics, correlations with experimental heat transfer data, pressure drop functions, advanced furnace calculation methods, and a kinetic model of carbon formation [419],... 

In many modern top-fired reformers the heat flux calculated for the inner tube wall surface is around 60 000 W/m2, although in some designs it cam be as high as 75 000 W/m2. The maximum heat flux may be 1.4 to 2 times higher. In side-fired and terraced-wall furnaces, where the mean fluxes are generally in the range of 60 000-85 000 W/m2, the difference between mean and maximum flux is much smaller, as shown in Figure 37 [444],... 

In the side-fired reformers the burners are located in the wall, and the box accomodates one or two rows of tubes, which receive their heat mainly by radiation from the walls of the furnace box. This is claimed to provide a very uniform heat distribution, which may additionally be adjusted by control of the individual burners. The larger number of burners makes fuel and preheated combustion air distribution more complicated and more expensive. As the heigth and width of the reformer are fixed by the radiation geometry of the tubes and furnace box walls, it is only possible to... 

The terraced-wall type, developed by Foster Wheeler may be regarded as an intermediate between the side-fired and bottom-fired tubes. The reformer has inclined walls with several terraces on which upward firing burners are installed. This unique burner positioning makes it possible to adjust the heat flux in each zone. Figure 41 is a schematic drawing of the Foster Wheeler terraced-wall furnace [426],... 

The second version has a S/C ratio of 2.5 and shift conversion with medium- and low-temperature catalysts, both copper-based. For C02 removal Selexol or aMDEA is chosen. The synthesis is performed at 140 bar with a Topsoe two-bed S 200 radial converter, followed by a single-bed radial S 50 converter (S 250 configuration). After the converters, high-pressure steam is generated. An additional proprietary item is the side-fired reformer. 

Industrial steam refonner Minimization of methane feed rate and maximization of the flow rate of carbon monoxide at the reformer exit. NSGA Side-fired steam reformer operation was optimized. Rajesh et al. (2000)... 

The bottom-fired reformer is classified into two types, one with the reforming gas flowing down the tube (as in top-fired and side-fired) and the other where the process gas flows up the reformer tubes. The burners are located on the floor on either side of two rows of reformer tubes. The flames are long and pencil thin. The system has a simplified air combustion distribution and single operating level. The system cannot handle more than 200-300 reformer tubes per radiant section and the tube metal temperatures at the process gas outlet are higher than the inlet. 

Model development for steam reformers Modelling of side fired furnaces Modelling of top fired furnaces Modelling of methanators Modelling of the catalyst pellets for steam reformers and methanators using the dusty gas model Computational algorithm... 

Figure 1.4 Side-fired tubular reformer design by Haldor-Topsoe. (Source Dybkjaer [2], Reproduced with permission of Elsevier.)...

Furnace Huge furnace (top/side fired) to supply the endothermic heat needed for the steam reforming reactions. Typical dimensions 21.8 X 35.5 X 13.7m. 

Figure 6.2.31 Temperature profile and heat fluxes in a side-fired prima reformer (adapted fom AppI, 1999).

Singh, C. P. P. Saraf, D. N., Simulation of Side Fired Steam-Hydrocarbon Reformers,... 

The steam reformer is a large process furnace in which catalyst-filled tubes are heated externally by direet firing to provide the necessary heat for the reactions taking place inside the reformer tubes. In methanol service, fired tubular reformers typicalfy come in two principal types downfired and side-fired. 

The Foster Wheeler reformer furnace is a Terrace-Wall furnace. The unique feature of this side-fired design is the burner location (Fig. 27 and 28). The burners are directed at the walls of the furnace, which radiate heat to the tubes. As with the top-fired reformer, the process gas enters the top and passes to the bottom. Unlike many top-fired furnaces, the terrace-walled furnace tubes have... 

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. 

Compared to a fired reformer, catalyst tube damage is less likely. This is because direct flame impingement cannot occur, and flue gas distribution is not a concern. The maximum tube metal temperature is also limited to the temperature of the shell-side gases. Since die reformer burners have been eliminated, process control is less complicated. And the lack of a flue gas stream reduces emissions of NOx and C02 by as much as 60% to 75%203. 

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