Heat exchange reforming Catalyst

Description Syngas preparation section. The feedstock is first preheated and sulfur compounds are removed in a desulfurizer (1). Steam is added, and the feedstock-steam mixture is preheated again. A part of the feed is reformed adiabatically in pre-reformer (2). The half of feedstock-steam mixture is distributed into catalyst tubes of the steam reformer (3) and the rest is sent to TEC s proprietary heat exchanger reformer, "TAF-X" (4), installed in parallel with (3) as the primary reforming. The heat required for TAF-X is supplied by the effluent stream of secondary reformer (5). Depending on plant capacity, the TAF-X (4) and/or the secondary reformer (5) can be eliminated. 

UOP uses a reformer with moving bed of platinum catalyst and continuous regeneration of a controlled quantity of catalyst (Fig. 19-23c). Acrylonitrile is made in a fixed fluidized bed by reacting propylene, ammonia, and oxygen at 400 to 510°C (752 to 950°F) over a Bi-Mo oxide catalyst. The good temperature control with embedded heat exchangers permits catalyst life of several years. 

Convective reformers result in less waste heat. The flue gas as well as the product gas is cooled by heat exchange with the process gas flowing through the catalyst beds, so that they leave the reformer at about 600°C. The amount of waste heat is reduced from 50% in the conventional design to about 20% of the fired duty in the heat exchange reformer. This means that the steam generated from the remaining waste heat just matches the steam needed for the process, so that export of steam can be eliminated. 

Figure 9.37 Design concepts of IdaTech steam reformers left, tubular fixed bed steam reformer reactors are placed around a central burner right, heat-exchange reformer the pre-reformer is placed in the outer area ofthe device while the reformer is more in the centre the combustion gases ofthe homogeneous burner pass through several annular gaps between the annular catalyst beds for heating [105].

In the heat exchange reforming case with heat exchange between the catalyst bed and a fluid with temperature T either on the outside at r = R or with an internal tube at r = Rj, the boundary condition can be written as ... 

SMART H2 [Steam Methane Advanced Reformer Technology] A process for making hydrogen by the steam reforming of methane. It differs from similar systems in housing the catalyst within a proprietary heat exchanger. Developed by Mannesmann KTI in 1996 it was planned for installation in Salisbury, MD, in late 1997. 

The coupling of SR with POX is termed autothermal reforming (ATR). The exact definition varies. Some define ATR as an SR reaction and a POX reaction that take place over microscopic distances at the same catalytic site thus avoiding complex heat exchanging (16). Others have the less restrictive definition that ATR occurs when there is no wall between a combined SR reaction and catalytic POX reaction. ATR is carried out in the presence of a catalyst that controls the reaction pathways and thereby determines the relative extents of the POX and SR reactions. The SR reaction absorbs part of the heat generated by the POX process reaction, limiting the maximum temperature in the reactor. The net result is a slightly exothermic process. 

There have been fuel processor configurations where a non-catalytic POX is placed in series with a steam reformer. Without catalyst, the POX reaction has to be at a higher temperature than the steam reformer reaction. These reactions have to take place in separate compartments with heat exchange and a wall between them (13). This configuration is not considered within the definition of autothermal reforming. 

Figure 17.13. Multibed catalytic reactors (a) adiabatic (b) interbed coldshot injection (c) shell and tube (d) built-in interbed heat exchanger (e) external interbed exchanger (f) autothermal shell, outside influent-effluent heat exchanger (g) multishell adiabatic reactor with interstage fired heaters (h) platinum-catalyst, fixed bed reformer for 5000 bpsd charge rate reactors 1 and 2 are 5.5 ft dia by 9.5 ft high and reactor 3 is 6.5 x 12.0 ft.

Dudfield et al. [88] presented results generated in the scope of the Mercatox program funded by the European Community aimed at a combined methanol steam reformer/combustor with consecutive CO clean-up by PrOx. First, various catalysts were tested for the reaction as micro spheres in a test reactor which was similar to a macroscopic shell-and-tube heat exchanger (Figure 2.57). 

Figure 2.81 Network of 27 catalyst beds (five for pre-reforming, nine for reforming, nine for catalytic combustion to supply the heat, two for water-gas shift and two for preferential oxidation) and of 20 heat exchangers [128]...

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