Steam reformer/heat exchanger

Figure 23. Methanol—steam reformers, heat exchangers, combustor, and selective oxidation reactors the body materiai was stainless steel. ...

Integrated Steam Reformer/Heat Exchanger for Isooctane... 

Heat exchange autothermal reforming, with a process gas heated steam reformer (heat exchange reformer) and a separate secondary reformer, or in a combined autothermal reformer, using excess or enriched air (under-stoichiometric or stoichiometric H/N ratio)... 

Figure 7.12 Steam reformer/heat-exchanger with catalytic burner and additional heat-exchanger as developed by Whyatt e o/. [517].

Motorola cooperated with Engelhard and the University of Michigan to develop a microstructured steam reformer in a project funded by the US Department of Commerce s Technology Administration [55]. The integrated fuel processor-fuel cell system consisted of an evaporator, a combustor, a reformer, heat exchangers, insulation layers and the fuel cell. Ceramic technology was used. The device had a maximum power output of 1W [56]. 

For a fuel cell system incorporating fuel (e.g., CH,) processing the HMM becomes much more complicated. The temperatures of the hydrodesulfurization unit, the reformer, the water-gas shift reactors, the preferential oxidizer, and the stack are all need to be properly controlled and maintained. There will be a heat exchanger between every two adjacent units mentioned above. For steam reforming, heat is needed to generate vapor from liquid water for the steam reforming reaction and the subsequent water-gas shift reactions. The conversion of liquid water to steam is typically carried out in one or more of the heat exchangers mentioned above.". 

Hydrogen plants for fuel cells should have no steam export (Stahl et al., 1985 and Rostrup-Nielsen, et al., 1991b). The heat produced by the fuel cell is sufficient for raising process steam. Therefore, heat exchange reformers are the preferred choice. The concept shown in Figure 5 was developed for this application. 

The emerging gas, now containing only 0.25% CH4, is cooled in heat exchangers which generate high-pressure steam for use first in the turbine compressors and then as a reactant in the primary steam reformer. Next, the CO is converted to CO2 by the shift reaction which also produces more H2 ... 

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. 

H2 production from ethanol (as well as methanol) employs these methodologies either as such or after slight modifications, especially in the ATR process, wherein a separate combustion zone is usually not present (Scheme 3). A mixture of ethanol, steam and 02 with an appropriate ethanol steam 02 ratio directly enters on the catalyst bed to produce syngas at higher temperature, around 700 °C.18,22 The authors of this review believe that under the experimental conditions employed, both steam reforming and partial oxidation could occur on the same catalyst surface exchanging heats between them to produce H2 and carbon oxides. The amount of 02 may be different from what is required to achieve the thermally neutral operation. Consequently the reaction has been referred to as an oxidative steam reforming... 

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. 

Pfiefer et al. are developing a methanol fuel processor system using steam reforming for a 200 Wg fuel cell based power supply. The researchers are currently working on the methanol reformer reactors, heat exchangers, combustors, and preferential oxidation reactors (Figure 23) for the system. The reactor bodies are either stainless steel or copper. 

Unlike the methane steam reformer, the autothermal reformer requires no external heat source and no indirect heat exchangers. This makes autothermal reformers simpler and more compact than steam reformers, resulting in lower capital cost. In an autothermal reformer, the heat generated by the POX reaction is fully utilized to drive the SR reaction. Thus, autothermal reformers typically offer higher system efficiency than POX systems, where excess heat is not easily recovered. 

Process gases leaving the steam reformer are at temperatures of about 1580°F to 1,620°F (860°C to 880°C). This heat is recovered in heat exchange systems for use in boilers and overall process applications. 

The most effective method of SNG production with an HTGR is the stcam-carbon reforming process in which superheated steam reacts with pulverized coal to form methane-rich SNG. A system for accomplishing this process is shown in Fig. 24. In this system, an intermediate heat exchanger (1HX) has been used to isolate the nuclear heat source from the process steam, thus allowing the use of conventional equipment for... 

One-dimensional models of a solid oxide fuel cell (see Chapter 9) and a methane-steam reformer [19, 20] were incorporated into the ProTRAX programming environment for transient studies. Lumped parameter ProTRAX sub-models were used for the remaining system components (heat exchangers, turbomachinery, valves, etc ). A schematic of the model is provided for reference in Figure 8.21. 

In the evaluation of the regenerative heat exchange option, it is instructive to consider the heat exchange techniques presently employed in the following chemical processes styrene synthesis, steam reforming, and hydrogen cyanide production (Table 1). 

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