Reforming process for synthesis gas production and related plant

A reforming process for synthesis gas production from a mixture of hydrocarbons comprising the steps of:

• a pre-reforming step, in which a process mixture, comprising said mixture of hydrocarbons and steam, is subjected to a preliminary catalytic conversion reaction, obtaining a partial conversion product comprising hydrogen, carbon oxides and hydrocarbons, said pre-reforming step carried out in pseudo-isothermal conditions controlling the thermal profile of the pre-reforming step by keeping the temperature of the catalyst used in the pre-reforming step substantially constant through indirect heat exchange, and
• a main reforming step, in which said partial conversion product is subjected to a conversion completion reaction, obtaining said synthesis gas,
• wherein no oxygen is fed to the pre-reforming step, and
• wherein at least one part of said partial conversion product obtained in said pre-reforming step is subjected to heating and then used as operating heat exchange fluid for supplying heat through the indirect heat exchange in said pre-reforming step.