Hydrocarbon converter furnace

A hydrocarbon converter furnace having an upper convection heating section and a lower radiant heating section, and tubing extending through said sections to convey a fluid hydrocarbon feed and steam in sequence through the convection and radiant heating sections, wherein the tubing comprises:

• (a) a common feed section and multiple branches extending therefrom in the radiant section of the furnace, each of said branches having an inlet in fluid communication with the feed section so that hydrocarbon and steam flow from the feed section into each of said branches,
• (b) valve means in each of said branches for controlling the rates of flow of hydrocarbon and steam in said branches to reduce differential coking therein,
• (c) said branches extending generally upright in and relative to said radiant heating section of the furnace, the feed section including a downcomer and a U-shaped section, both extending in said radiant section of the furnace and through which hot feed hydrocarbon and steam are fed upwardly to said branches,
• (d) said branches having main extents in said radiant section, and said valve means including control valves in each of said branches having an opening and having separately movable stoppers movable lengthwise of and within the branches for increasing or decreasing the flow rates of hydrocarbon and steam through the opening of the control values in the main extents of said branches in said radiant section,
• (e) said stoppers including nozzle means for controllably introducing dilution steam therethrough into the branches, said nozzle means including separately adjustable valves to separately control the amount of dilution steam fed to each of said branches through the nozzle means of each stopper to thereby minimize differential coking in the branches.