forced flow vapor generating unit

Claim 1

IN A FORCED CIRCULATION FLUID HEATING UNIT, WALLS DEFINING A FURNACE CHAMBER FOR THE FLOW OF HEATING GASES, BURNER MEANS SUPPLYING HIGH TEMPERATURE HEATING GASES TO SAID CHAMBER, A ROW OF UPWARDLY EXTENDING LATERALLY SPACED INITIAL UPFLOW TUBES DISPOSED IN SAID FURNACE AND ARRANGED FOR PARALLEL FLOW OF FLUID THERETHROUGH, A ROW OF UPWARDLY EXTENDING LATERALLY SPACED SECOND UPFLOW TUBES DISPOSED IN SAID FURNACE AND ARRANGED FOR PARALLEL FLOW OF FLUID THERETHROUGH, MEANS FOR SUPPLYING A VAPORIZABLE FLUID OF SUBSTANTIALLY THE SAME ENTHALPY IN PARALLEL FLOW RELATION DIRECTLY FROM A COMMON SOURCE TO THE LOWER INLET ENDS OF SAID INITIAL UPFLOW TUBES, AND MEANS CONNECTING SAID INITIAL UPFLOW TUBES FOR SERIES FLOW OF FLUID TO SAID SECOND UPFLOW TUBES AND EFFECTING A SUBSTANTIALLY UNIFORM DISTRIBUTION OF THE FLUID DISCHARGING FROM SAID INITIAL UPFLOW TUBES TO SAID SECOND UPFLOW TUBES AT A SUBSTANTIALLY UNIFORM ENTHALPY, SAID LAST NAMED MEANS COMPRISING A SPHERICAL VESSEL, DOWNFLOW TUBULAR MEANS DISPOSED EXTERNALLY OF SAID FURNACE AND CONNECTED FOR SERIES FLOW OF FLUID FROM SAID INITIAL UPFLOW TUBES AND TO SAID VESSEL, AND