Process and apparatus for controlling reaction temperatures with heating arrangement in series flow

A channel reactor apparatus for contacting reactants with a particulate catalyst, indirectly heating the reactants with a heating fluid and reheating the heating fluid with a reheating fluid, said apparatus comprising:

• a plurality of reaction stacks with each reaction stack comprising a plurality of parallel plates extending vertically and horizontally and defining heating channels and reaction channels in each reaction stack;
• a distribution system for passing a reactant stream to the reaction channels of each reaction stack in parallel flow;
• a withdrawal system for collecting the parallel flow of reacted reactants from each reaction stack;
• a heating fluid delivery conduit for delivering a heating fluid to the heating channels of one of the reaction stacks located in a lead position;
• a plurality of intermediate conduits for passing the heating fluid in series flow from the reaction stack in the lead position, through the heating channels of reaction stacks located in an intermediate position, and to a reaction stack located in an end position;
• a heating fluid recovery conduit for recovering the heating fluid from the reaction stack in the end position;
• and
• a heater for reheating the heating fluid as it passes through an intermediate conduit.