Process and furnace for the steam cracking of hydrocarbons for the preparation of olefins and diolefins

摘要

The present invention relates to a process for the preparation of olefins by the cracking of hydrocarbons consisting in passing a mixture of hydrocarbons and steam flowing in a cracking tube disposed inside a radiation zone of a furnace. The process is characterized in that an increase of the cracking temperature of the mixture between the inlet and the outlet of the radiation zone is associated to a non-homogeneous distribution of the thermal power of the furnace, greater at the beginning of the cracking tube than at the end, and to a reaction volume which is greater in the second half of the length tube than in the first one. The present invention relates also to a cracking furnace in which between the inlet and the outlet of the radiation zone the diameter of the cracking tube increases and the thermal power of the heating means decreases.