Influence of the heat-flux profiles on the operation of primary steam reformers

The influence of the heat-flux axial profiles on the main variables of an i ndustrial primary steam reformer (i.e.; outlet methane conversion, process gas temperature, tube-skin temperature, and equilibrium approach) has been studied. By means of adjustments of the heat flux along the tube length, tw o different optimization problems have been proposed: (a) maximum methane c onversion for a given maximum allowable tube-skin temperature and (b) minim um tube-skin temperature for a fixed methane conversion, both for constant heat duty. The defined optimization problems have been solved using a one-d imensional heterogeneous model. This mathematical formulation accounts for the strong mass-transfer resistances by an appropriate solution of the mate rial balances within the catalyst. An equivalent annular model has been use d to represent the complex geometry of the catalyst particle. The simulatio n arid optimization results indicate that the heat flux strongly influences the reactor performance. Indeed, adequate selections of the heat-flux dist ribution along the reactor length would increase the production rate and/or extend the tube lifetime significantly.