Abstract: A vapor generator which includes an upright furnace section the boundary walls of which are formed by a plurality of tubes for passing fluid through the length of the furnace section to convert a portion of the fluid to vapor or to heat the fluid. One portion of the tubes forming one of the boundary walls are bent out of the plane of the latter wall for connection to a plurality of headers. A single tube extends upwardly from each of the headers in fluid communication with the other tubes connected to said header, with the single tubes being disposed in a spaced relationship to form a screen for the passage of combustion gases from the furnace section to a heat recovery section disposed adjacent the furnace section.

Abstract: A vapor generating system in which a vapor generating section and a superheating section are connected in a series flow relationship with a fluid separating section extending between the vapor generating section and the superheating section. The vapor generating section includes an upright furnace section formed by a plurality of tubes, a portion of which extend at an angle with respect to the horizontal plane for passing fluid through the length of the furnace section to convert a portion of the fluid to vapor or to heat the fluid.