Heating device having dumbbell-shaped reaction tubes therein

Claim 1

In a furnace for the thermal decomposition of hydrocarbons comprising a chamber having heating means positioned at opposite locations therein, and at least one elongate reaction tube spaced between said heating means; the improvement which comprises said reaction tube having a cross sectional dumbbell-shape and having in cross section perpendicular to the longitudinal axis of said tube a major and minor diameter of the following interrelated characteristics: 0° < Ψ < 60° 10 mm < a < 60 mm 5 mm < b < 2000 mm where a = the radius of curvature of the inside surface of the reaction tube at the circular portions of said dumbbell-shape, b = radius of curvature of the inside surface of the reaction tube at the narrow portion of said dumbbell-shape and, Ψ = the angle between a line connecting the center of curvature at the narrow portion and the center of curvature at the circular portion and a line extending from said center of curvature at the narrow portion through the center of the narrow part and wherein the major diameter of the dumbbell-shaped reaction tube is parallel to each of said heating means.