Furnace having tubes for cracking hydrocarbons

Abstract

A furnace for cracking of hydrocarbons, comprising one or several tubes through which the hydrocarbons flow during intensive heating and subsequent cracking. The starting material for the process can be e.g. naphtha or propane, mixed with a small amount of steam. When gases flow through the tube or tubes in the furnace, its temperature is increased up to about 850.degree. C. In order to achieve this, the temperature in the furnace compartment is 1100.degree.-1200.degree. C., and the temperature of the gases in the tubes in the furnace can then exceed 1100.degree. C. The tubes are made from an alloy comprising 15-30 weight % chromium, 3-10 weight % aluminum, the remainder of the composition being mainly iron. This alloy allows significant extension of the possible duration of operation without exchange of the tubes. A further improvement can be achieved by the formation on the inner walls of the tubes of a layer of aluminum oxide, obtained by oxidation of the tubes before the furnace is first used. The tubes are preferably seamless, and formed by extrusion of powder metallurgical billets.

Dependencies are inferred from the claim text.