A furnace for gas fields, refineries reforming, petrochemical plants, or hydrogen generation by gasification may include: a radiant zone; a convective zone; and a first and second series of pipes through which at least two segregated process gas flows respectively pass. A first process gas flow may enter the furnace through the convective zone and, flowing through the first series of pipes, may leave the furnace through the radiant zone, or alternatively the first process gas flow may enter the furnace through the radiant zone and, flowing through the first series of pipes, may leave the furnace through the radiant zone. At least a second process gas flow may enter the furnace through the convective zone, may pass through the second series of pipes, and may leave the furnace through the convective zone. The second of series of pipes may be made of material resistant to acid gases.