Method for high temperature wastewater treatment and reuse in MTO process

Abstract

The invention relates to a method for treating and reusing high-temperature stripping purified wastewater produced in the process of transferring oxygenated compounds into olefins by using a high-temperature separation membrane. The combination process can effectively remove the impurities such as metal ions and organic micro-molecules and the like in stripping purified water, and the treated purified water in a tower kettle can meet the quality requirements of makeup water for middle and low-pressure boilers or the quality requirements of the makeup water in the MTO process. The invention effectively overcomes the defects exiting in the method for treating and reusing the stripping purified water without condensation in the MTO process, and lowers or reduces the consumption of circulating cooling water in the process of cooling firstly and then treating, thereby saving a large amount of boiler water and recycling the thermal energy of produced high temperature wastewater, and providing a stable and efficient way for high temperature wastewater treatment and reuse of relevant enterprises.

Description

[technical field] [0001] The invention relates to the field of wastewater treatment, in particular to a method for treating high-temperature wastewater of an MTO process by utilizing membrane separation technology. [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. The research and development of methanol to light olefins (MTO) process is a new process route for the production of chemical products from non-petroleum resources. As the technology of producing methanol from coal or natural gas through synthesis gas is becoming more and more mature, MTO has become a production route that has attracted much attention. [0003] The chemical reaction equation and thermal effect of using methanol as ...

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Problems solved by technology

[0010] Chinese patent application CN101139117A and CN101139118A disclose a kind of wastewater treatment process containing methanol and dimethyl ether, the specific method is: the wastewater containing methanol and dimethyl ether is pressurized to exchange heat with the purified water at the bottom of the stripping tower, Then enter the stripping tower, the gas mixture such as methanol produced at the top of the stripping tower enters the reflux tank after heat exchange, and part of it returns to the top of the stripping tower as reflux; the other part is sent to the outside of the device or used as a raw material for the MTO device; The purified water in the stripping tower after heating is exchanged with the wastewater containing methanol and dimethyl ether, and then sent to the outside of the device. The total content of methanol and dimethyl ether in the purified water after stripping is not more than 100ppm, which can meet the requirements of sewage treatment. According to the requirements of influent water quality, biochemical treatment is used as the main process to discharge and treat process wastewater up to standard. However, the patent does not directly treat the high-temperature process wastewater discharged from the stripping tower kettle to recover low-grade heat and reduce waste water for reuse. make specific reports

[0011] The above-mentioned foreign patents mainly consider the reuse of the process itself at the point of water demand from the process itself, but since the MTO process itself is a process in which olefins and water are continuously produced, when the water cycle of the process itself reaches a stable level, a large amount of water will still be discharged , the above-mentioned patents have no reports on the treatment and reuse of the remaining process wastewater; while the Chinese patent application mainly adopts the steam stripping method to recycle a large amount of organic matter in the process wastewater, so that the process wastewater can be purified to reach the water quality of the sewage treatment plant As for the direct treatment, indirect treatment and detailed recycling method of the high-temperature process wastewater in the tower kettle after stripping, there is no report in the patent application

[0012] In addition, although patent applications CN101088922A and CN101092258A respectively disclose a method for membrane separation and purification of high-temperature condensate water and a method for membrane integration process to treat high-temperature condensate water, they use inorganic ceramic microfiltration or ultrafiltration membranes and nanofiltration membranes from different angles. Methods to remove impurities such as suspended solids, oil, colloids, soluble small molecular organics and some inorganic ions in steam condensate water, but neither of them has been studied and reported on the treatment of high-temperature wastewater related to MTO process

Therefore, there are currently no data reports on the advanced treatment and reuse of high-temperature wastewater from the MTO process.

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