Treatment and reuse method of waste water in methanol-to-olefin process

Abstract

The invention relates to a treatment and reuse method of waste water in a methanol-to-olefin (MTO) process. The method comprises the following steps: (1) an effluent from an MTO reactor is subjected to the waste heat recovery through a waste heat boiler and then cooled and separated through a separation tower to generate high concentration MTO waste water; (2) the effluent from the MTO reactor isfurther cooled, a water phase is generated at the bottom of the separation tower, an olefin gas is generated at the top of the separation tower, and the olefin gas is further purified by compression and water scrubbing; (3) the water phase from the bottom of the separation tower and a water phase from bottom of a water scrubbing tower are treated by steam stripping, and a water phase generated atthe bottom of a steam stripping tower is cooled through a tower bottom heat exchanger to generate low concentration MTO water; (4) the low concentration MTO water is homogenized; (5) the low concentration MTO water is subjected to the coagulating sedimentation treatment after the homogenization; (6) the low concentration MTO water is subjected to the aerobic aeration treatment after the coagulating sedimentation treatment; (7) the effluent water is settled after the aerobic aeration treatment; and (8) the effluent water is subjected to the flocculation filtration treatment after the settlement. The method can not only reduce the consumption of the fresh water in the MTO production, but also reduce the discharge of pollutants to the environment in the MTO production.

Description

technical field [0001] The invention relates to a treatment and reuse method for wastewater from an oxygenate-to-olefins process, in particular to a treatment and reuse method for wastewater from a methanol-to-olefins process. Background technique [0002] Low-carbon olefins such as ethylene and propylene are important organic chemical raw materials and play a very important role in modern petroleum and chemical industries. Traditionally, the source of ethylene and propylene is mainly steam cracking of hydrocarbons, and the raw material is mainly naphtha. In recent years, the Oxygenate-to-Olefins (OTO) process, especially the Methanol-to-Olefins (MTO) process has become increasingly mature, and is expected to start large-scale application in the short term. [0003] The chemical reaction equation and thermal effect of producing ethylene and propylene from methanol are: [0004] 2CH 3 OH→C 2 h 4 +2H 2 O (ΔH=11.72KJ / mol, 427°C) [0005] 3CH 3 OH→C 3 h 6 +3H 2 O (ΔH=...

AI Technical Summary

Problems solved by technology

As for whether the purified water contains other pollutants and how to further treat the purified water, the patent does not involve

[0017] It is not difficult to see from the above-mentioned published literature that at present, MTO wastewater treatment methods mainly focus on the physical separation of water and pollutants, and the proposed wastewater reuse point is only in principle. As for how to further improve the wastewater that needs to be discharged Disposal and reuse are basically not involved

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