Tubular reforming limits of operation

The limit of operation of a tubular steam reformer is often requested. One such limit is the maximum metal temperatures on the catalyst tubes (refer to Section 3.2.2), but it must also be known how this limit is influenced by variations in the catalyst activity and heat transfer. 

Three individual runs were performed, where the firing profile was changed as dramatically as possible. A survey of the runs is shown in Table 3.3 [120], 

Equal firing in 5 rows No firing in bottom row. Equal firing in the other 4 rows. Only firing in the 2 bottom rows. 

The temperature profile in Run A corresponds to an ordinary sidewall-fired furnace. The temperature profiles in Run B allow establishment of reforming equilibrium at the outlet due to the reduced firing in the bottom. The profile in Rim C simulates maximum heat flux at the very bottom similar to a bottom-fired reformer. It is evident that such changes can only be performed in a pilot plant. 

F igure 3.18 Measured temperature approach to the methane reforming reaction at the outlet of the reformer as a function of local heat flux for the three runs. A, B, and C. 

---