Process for synthesizing ammonia from hydrocarbons

An ammonia synthesis process comprising the generation of synthesis gas from hydrocarbons by the primary reforming of said gases with steam and by the secondary reforming of the resulting gaseous mixture with oxygen, characterized in that it comprises the steps of subjecting a part, not passed through the primary reforming, of the starting hydrocarbon mixed with the steam to a tertiary reforming in which the necessary heat is supplied, by means of indirect heat exchange, by the gaseous reaction mixture leaving the secondary reforming;

• said tertiary reforming being of the mixing type in which the reformed gaseous mixture, which forms by flowing inside pipes containing the catalyst of said tertiary reformer, directly mixes, before said heat exchange occurs, with the gaseous reaction mixture leaving the secondary reforming, such mixture providing, from outside the pipes, the heat necessary for said tertiary reforming;
• causing the ammonia synthesis to occur at an absolute pressure lower than 100 kg/cm.sup.2 with drying of the gas conveyed to the synthesis reactor by employing molecular sieves;
• absorbing the ammonia contained in the reacted gas with water;
• and subjecting the ammonia solution so obtained to distillation to obtain a relatively concentrated ammonia product.