Thermal cracking tube with fluid agitating element

A thermal cracking tube with an agitating element to be heated from outside, the thermal cracking tube comprising,

• a tube having a tube axis with one end and another end, wherein a fluid inlet is on the one end and a fluid outlet is on the another end, the tube having an inner surface with a diameter of at least about 30 mm and being configured to thermally crack a hydrocarbons-containing feedstock fluid material over a reaction temperature range, and
• at least one agitating element for agitating the feedstock fluid material, wherein the agitating element is provided on the inner surface of the tube and extends inwardly from the inner surface of the tube and has an inwardly facing top portion,
• wherein
• the agitating element is helically inclined to or is orthogonal to a longitudinal direction of the tube axis, and has oppositely inclined surfaces across the top portion thereof,
• the oppositely inclined surfaces comprise an inlet-side inclined surface on the fluid inlet side and an outlet-side inclined surface on the fluid outlet side,
• when the agitating element is viewed in a sectional plane including the tube axis, the top portion of the agitating element is located on the fluid inlet side or the fluid outlet side, relative to a center of a width of the agitating element, wherein
• (1) the inlet-side inclined surface has a concave shape and the outlet-side inclined surface has a convex shape, or
• (2) the inlet-side inclined surface has a convex shape and the outlet-side inclined surface has a concave shape.