Olefin separation system and olefin separation method

Abstract

The invention provides an olefin separation system and an olefin separation method. The olefin separation system comprises a demethanation unit. The demethanation unit comprises a primary demethanation tower, a pressure swing adsorption system and a secondary demethanation tower. A first gas-phase flow pipeline is arranged between the outlet located on the top of the primary demethanation tower and the inlet of the pressure swing adsorption system; and a hydrocarbon-rich gas flow pipeline is arranged between the outlet located on the top of the pressure swing adsorption system and the inlet of the secondary demethanation tower. The gas to be separated is unclearly cut or clearly cut via the primary demethanation tower, so that the first gas-phase flow obtained by a manner of processing the gas to be separated via the primary demethanation tower can be effectively divided into a hydrocarbon-rich gas flow and a hydrogen-rich flow after being adsorbed by the pressure swing adsorption system, CH4 / H2 molecular ratio in the hydrocarbon-rich gas flow entering the primary demethanation tower is enlarged, the differential pressure of CH4 on the top part of the primary demethanation tower is increased, and the energy consumption required by temperature reduction and the investment and the operation cost on olefin separation are reduced.

Description

technical field [0001] The invention relates to the field of gas separation, in particular to an olefin separation system and an olefin separation method. Background technique [0002] In addition to ethylene and propylene, petroleum cracking gas, refinery dry gas and methanol-to-olefin product gas also contain a large number of other components, such as hydrogen, methane, acetylene, propane and nitrogen. Since ethylene and propylene are important chemical raw materials, Therefore, the above petroleum cracking gas, refinery dry gas and methanol-to-olefin product gas can be used as raw materials to separate ethylene and propylene. At present, the cryogenic separation method is the most mature and widely used. [0003] Typical conventional cryogenic separation methods have many disadvantages. For example, it usually requires 4 to 5 stages of compression of the raw material gas, which requires a large amount of low-temperature cooling medium. For example, methane-hydrogen separ...

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Problems solved by technology

[0005] The above-mentioned conventional cryogenic technology and Lummus technology are all difficult to obtain the ideal molecular ratio of methane and hydrogen by one-time demethanization treatment, which leads to high energy consumption, large ethylene loss and high investment in the process of separating ethylene from tail gas Shortcomings, the present invention is mainly based on the improvement of the Lummus technology in order to reduce energy consumption and reduce ethylene loss

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