Steam cracking method

Abstract

The present invention discloses a steam cracking method, which is performed in a vaporization apparatus and a cracking furnace, wherein the cracking furnace comprises a convection section and a radiation section, and the convection section comprises pre-heating alignment tubes and a connection box positioned between the pre-heating alignment tubes outside the cracking furnace convection section. The method comprises that unsaturated hydrocarbon is vaporized in the vaporization apparatus to obtain gas-phase unsaturated hydrocarbon, the gas-phase unsaturated hydrocarbon and diluted steam are mixed, pre-heating is performed, one part of the pre-heated mixture is introduced into the outlet position of the cracking furnace radiation section, and the other part is introduced from the middle position of the cracking furnace radiation section and is cracked, wherein a diameter ratio of the pre-heating alignment tubes to the connection box is 1:5-12, and the middle position of the cracking furnace radiation section is positioned at the place having the height of 1 / 4-4 / 5 of the height of the cracking furnace. With the method of the present invention, the temperature increasing rate of the cracking raw material in the cracking furnace tube is improved so as to improve the selectivity of the cracking reaction, such that the yields of ethylene, propylene and butadiene are improved.

Description

technical field [0001] The invention relates to a steam cracking method. Background technique [0002] Low-carbon olefins such as ethylene, propylene and butadiene are important basic raw materials for the petrochemical industry. At present, the method of producing low-carbon olefins is mainly based on the tube furnace petroleum hydrocarbon steam cracking process. According to statistics, about 99% of ethylene, more than 50% of propylene and more than 90% of butadiene in the world are produced through this process. [0003] There are two main sources of raw materials for the production of low-carbon olefins such as ethylene, propylene and butadiene. One is light hydrocarbons by-product of natural gas, such as ethane, propane, butane and natural gasoline, etc.; Products, such as refinery gas, naphtha, diesel, and secondary processing products, such as coking hydrogenated naphtha, hydrogenated tail oil, etc. A common feature of these raw materials is that most of them are sa...

AI Technical Summary

Problems solved by technology

[0031] The purpose of the present invention is to provide a new steam cracking method in order to overcome the problem that unsaturated hydrocarbons are injected into the cracking furnace as cracking raw materials and coking will occur in the convection section

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