Hydrogen by steam reforming of hydrocarbons

Steam reforming of natural gas and other hydrocarbons remains the cheapest route to large-scale commercial production of hydrogen [251] [414] [426]. The costs are increased if CCS is included as illustrated in Table 2.1. 

A low steam-to-carbon ratio results in a more energy efficient plant and thus lower operating costs. A low steam-to-carbon ratio increases the amount of uneonverted methane from the reformer, but this is eompensated for by increasing the reformer outlet temperature, typically to 900-950°C. 

The transferred heat is calculated as shown in Example 1.3. It is evident that the reformer is significantly smaller than for the previous design. 

The basic thermodynamic data of the feed and product are shown in 

It is seen in Table 2.3 that the exergy balance is fulfilled, whereas the LHV balance is not due to the liquid water. If the balance should be fulfilled, it is necessary to set the LHV of the liquid water to -88 kJ/mol CH4 corresponding to the heat of evaporation. 

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Figure 4.1. A process for producing hydrogen by steam reforming of hydrocarbons (1) reforming furnace (2,3) purification section, (4) shift converter, (5) pressure swing adsorption.

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