Hydrogen supply system

Figure 15.14. Optimal infrastructure configuration at different market penetration levels for a coal-based hydrogen supply system with carbon capture and sequestration in Ohio, USA (Johnson et al., 2006).

Small-scale reforming systems are being pursued by a number of companies developing fuel cell electrical generation systems for home and automotive fuel cell applications. Before these systems become affordable and simple enough to be used as home electrical system components, they may be cost effective for industrial hydrogen supply systems.48... 

Having discussed possible hydrogen supply systems and general design criteria, we now pose a series of "system-level" questions about transition to a hydrogen energy system. 

Fabricate and evaluate 1-kg H2 and 5-kg H2 capacity hydrogen supply systems in conjunction with proton exchange membrane fuel cell (PEMFC) systems. 

Conduct preliminary performance modeling of the combined PEMFC and hydrogen supply system under steady-state and transient conditions to establish dynamic control requirements. 

The Japanese cities Toyohashi (population 350,000) and Soga (population 170,000) have been selected as model cities in WE-NET to investigate the feasibility of a hydrogen supply system in a hydrogen-oriented society [78]. 

Kolb G, Baier T, Schilrer J, Tiemann D, Ziogas A, Ehwald H, Alphonse P (2008) A micro-structured 5 kW complete fuel processor for iso-octane as hydrogen supply system for mobile auxiliary power units. Part 1 development of autothermal reforming catalyst and reactor. Chem Eng J 137 653-663... 

If 10 /kg is taken as the price at the fuel pump, corresponding to 6 /kg revenue at the production plant, and set as the reference value, then the profitable operation of a hydrogen supply system based on excess electricity can be expected in the long term. 

Sensitivity analyses identified criteria that are important for economic operation of hydrogen supply systems including the cost of power, specific investments in system components, and full-load hours of the electrolyzers. For the values cited... 

G. Kolb, T. Baier, J. Schiirer, D. Tiemann, A. Ziogas, S. Specchia, C. Galletti, G. German , Y. Schuurman, A micro-stmctured 5 kW complete fuel processor for iso-octane as hydrogen supply system for mohde auxiliary power imits Part 11. Development of water-gas shift and preferential oxidation catalysts reactors and assembly of the fuel processor. Chem. Eng. J., 2007, 138, 653-663. 

Although the simple hydrogen supply system layout as shown in Fig. 4.14 is operational in a laboratory envirorrment, additional valves are normally used in order to enhance the safety of system operation. This is normally achieved by inclusion of a shut-off valve upstream of the pressure reducer and a pressirre relief valve (safety valve) that will prevent hazardous pressure birild-up in the case of failtue of the pressure reducer (Fig. 4.15). The shut-off valve can be operated manually or as a control valve. Additioiral safety features may include a thermal activated fuse between the storage cylinder and shut off valve, filters, flow restrictors as well as a flame arrestor. 

Kolb, G., Men, Y., Schelhaas, K.P., Tiemann, D., Zapf, R., and Wilhelm, J. (2010) Development work on a microstructvu-ed 50kW ethanol fuel processor for a small-scale stationary hydrogen supply system. Ind. Eng. Chem. Res., 50 (5), 2554-2561. 

Similarly, if the anode of a fuel cell is supplied with hydrogen, then there will be a slight drop in pressure if the hydrogen is consumed as a result of a current being drawn from the cell. This reduction in pressure results from the fact that there will be a flow of hydrogen down the supply ducts and tubes, and this flow will result in a pressure drop due to their fluid resistance. This reduction in pressure will depend on the electric current from the cell (and hence H2 consumption) and the physical characteristics of the hydrogen supply system. 

The 97% hydrogen permeate gas is of sufficient purity and pre.ssure that it can be fed directly into the 256 psia hydrogen supply system. Typical operating conditions are provided in Table 15 7. The unit was operated at a low pressure ratio to deliver hydrogen to the refinery hydrogen supply system without recompression. This low pressure ratio resulted in a low hydrogen recovery of about 30%. 

FIGURE 9-5. Closed loop hydrogen supply system with pump (above) and ejector (below). 

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