PINNED FURNACE TUBES

摘要

In an embodiment of the invention, furnace tubes for cracking hydrocarbons having a longitudinal array of pins having i) a maximum height from 0.5-1.3 cm; ii) a contact surface with the tube, having an area from 0.1%-10% of the tube external surface area iii) a uniform cross section along the length of the pin. (i.e. they are not tapered); and iv) a length to diameter ratio from 1.5:1 to 0.5:1 have an improved heat transfer over bare fins and reduced stress relative to a fined tube.

主权项

1. A tube for use in the radiant section of a furnace for cracking hydrocarbons to produce olefins having on its exterior surface a series of pins in one or more linear arrays parallel to the longitudinal axis of the tube, said pins having:
i) a maximum height from 0.8 to 1 cm; ii) a contact surface with the tube, having an area from 0.1% to 10% of the tube external surface area; iii) a uniform cross section along the length of the pin; iv) length to diameter ratio from 1.5:1 to 0.5:1; v) a distance between consecutive pins within a given linear array is from 0.1 to 5 times the diameter of the pin; vi) from 2 to 6 linear arrays of pins radially spaced from 180° to 20° apart; and vii) the aggregate weight of the pins comprises from 5 wt. % to 25 wt. % of the weight of the tube.