Lightweight alkene separation method reducing absorbent usage amount and device thereof

Abstract

The invention discloses a lightweight alkene separation method reducing absorbent usage amount and a device thereof. Lightweight alkene reaction gas converted from oxygen-containing compound is subjected to a pre-treatment and then induced to a double-tower depropanization system. The product in the top of the towers of the depropanization system cools and is transported to a demethanation tower, in the top of the demethanation tower only propylene cooler is used to cool materials, the gas phase in the top of the tower is transported to a tower, which is provided with a heat exchanger in the middle or in the top, to absorb carbon dihydrocarbon, the gas discharged from the absorption tower is induced into a pressure swing absorption device to further recycle ethylene, recycled coarse ethylene gas mixes with lightweight ethylene reaction gas before returning to a section of compressor. The invention provides a non-deep-cold lightweight alkene separation method, which has the advantages of small investment, low energy consumption, small absorbent circulation volume and high material recovery rate.

Description

Technical field [0001] The present invention is the field of light -quality olefin separation and purification technology. It involves a raw material for a raw material (mainly a methanol, ethanol, di methaol, C4 ~ C10 alcohol compound or mixture, etc.).In the process of logistics (mainly ethylene and acryl), its product is separated by the separation method and equipment of its product light olefin gas. Background technique [0002] The sources of traditional ethylene and acrylic are mainly petroleum steam cracking. The raw materials are mainly petroleum oil, while my country's oil resources are short of shortage. This is the main reason to restrict the development of the ethylene industry in my country.With the increasing tension of oil supply, the otakosaidal compounds to make light olefins (OTO processes) have become a hotspot of research. Its representative methanol olefin technology (MTO) has become increasingly mature, and it has opened up coal or natural gas through gasif...

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Problems solved by technology

[0021] In summary, according to the characteristics of light olefin products from oxygenates, it is reasonable to avoid cryogenic separation; for the oil washing process, the main difference lies in the choice of absorbent and the sequence of the process arrangement, and its main disadvantages are : The amount of solvent circulation is very large, and the energy consumption of the cooling cycle after solvent regeneration is significant, and part of the absorbent will be used as fuel gas with the absorption tower top gas, which reduces the use value of the absorbent itself. The process has certain restrictions on the selection of solvents. Adding a desorption device and increasing the temperature of the demethanizer makes the loss of ethylene larger compared with the cryogenic process; for the improved "pre-cutting + oil absorption" and adding an expander process at the top of the demethanizer, both can reduce solvent circulation and Lower the tail gas temperature to increase the yield, but since the solvent comes from the inside of the system, the energy consumption is unavoidable during the solvent regeneration process of heating first and then cooling, and the solvent circulation will still increase the subsequent separation energy consumption, especially the content of propylene in the feed to the propylene refining tower Reduced, and it is necessary to establish a solvent cycle at cold start, which brings inconvenience to driving and parking

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