Process for performing an endothermic reaction

A process for performing an endothermic reaction in a reactor containing catalyst tubes, the catalyst tubes containing a catalyst promoting the endothermic reaction, the process comprising the steps of,

• a) contacting the catalyst contained in the catalyst tubes with a feed flow passing through the channels from an entrance end to an exit end;
• b) contacting an outer surface of the catalyst tubes with a flow of a heating medium having an initial heating temperature and flowing co-currently with the flow of feeds to heat the surface by convection;
• and
• c) mixing at least part of the heating medium after having been contacted with the catalyst tubes with a flow of fresh heating medium having a start temperature higher than the initial heating temperature to form the co-current heating medium having the initial heating temperature,
• wherein the reactor comprises a heat providing section containing heat providing means, the heat providing section communicating with an inlet end of a reactor section, the reactor section containing catalyst tubes and having an outlet end communicating with a head space section, the catalyst tubes being screened from heat radiation of the heat generating means, the reactor further comprising a recirculation section connecting the head space section to the heat providing section.