Method for recycling saponification wastewater generated in process of producing epoxypropane by adopting caustic soda saponification method
A technology for saponifying wastewater and propylene oxide, applied in chemical instruments and methods, water/sewage multi-stage treatment, water/sludge/sewage treatment, etc., can solve the problem of affecting the quality of soda ash, increasing production costs, and wasting water and salt resources and other problems, to achieve the effect of reducing the cost of brine refining, reducing the impact on the environment, and achieving zero discharge of wastewater
Active Publication Date: 2013-12-25
SHANDONG HAIHUA GRP CO LTD
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Problems solved by technology
[0002] In the process of producing propylene oxide by caustic soda saponification, a large amount of wastewater rich in sodium chloride and high COD will be produced. If it is discharged outside, it will not only cause waste of water and salt resources, but also cause serious environmental pollution.
At present, the treatment method of caustic soda saponification method propylene oxide saponification waste water is electrolysis saponification waste water, obtains caustic soda solution and is reused in propylene oxide production, as the processing method that the patent No. is 200710011073.0, this method is that saponification waste water is reclaimed, five-effect evaporation concentrates, The caustic soda solution obtained by diaphragm method electrolysis is used for the production of propylene oxide. This method can realize the recycling of resources, but there are problems such as long process flow, complicated process and high energy consumption; In line with the requirements of the ionic membrane caustic soda process, the electrolysis can only use the diaphragm caustic soda process, and the diaphragm caustic soda process has been listed in the "Guidance Catalog for Elimination of Outdated Production Process Equipment and Products in Some Industries (2010 Edition)" issued by the Ministry of Industry and Information Technology in 2010. Included in the elimination list
[0003] In the production of soda ash by the ammonia-soda method, the first step is to hydrate the solid raw salt into saturated brine, and then refine the saturated brine to make refined brine and enter the next process. The refining process is to remove calcium, magnesium ions, calcium In the production of soda ash, magnesium ions will generate calcium carbonate and magnesium carbonate water-insoluble matter, which seriously affects the quality of soda ash. Therefore, how to remove calcium and magnesium ions in the process of salting and improve the accuracy of brine is an important prerequisite to ensure the quality of soda ash. At present, large-scale In order to save fresh water, the ammonia-soda method soda ash production enterprises generally use seawater salt, and then refine it into saturated refined brine, and seawater contains a lot of calcium and magnesium ions. For example, in some areas, seawater contains 427mg / l of calcium ions and 1530mg of magnesium ions. / l, COD value 50mg / l, to remove these calcium and magnesium ions will bring a lot of refining costs and increase production costs
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Embodiment 1
[0015] The saponification wastewater with a COD of 1000mg / l is mixed with other industrial wastewater, and then treated for 36 hours by the multi-phase composite membrane bioreaction process, and then sent to the soda ash production system as salt water for the production of soda ash by ammonia-soda method.
Embodiment 2
[0017] First, the saponification wastewater with a temperature of 80°C, a COD content of 1200mg / l, and a NaCl content of 4.0wt% is stripped of some organic matter in the wastewater under the action of 0.4MPa steam, and then mixed with other industrial wastewater. Other industrial wastewater can be For fresh water, reclaimed water or other waste water with lower salinity and COD value than saponification waste water, dilute the mixed liquid to a COD content of 450mg / l and a salt content of 2.4wt%, and then treat it through multi-phase combined membrane biological reaction for 48 hours , and transported to the soda ash production system as salt water for the production of soda ash by ammonia-soda method.
Embodiment 3
[0019] First, the saponification wastewater is recovered heat in the form of flash steam through the injector, and then the saponification wastewater is mixed and diluted with reclaimed water to obtain a mixed solution. The COD in the mixed solution is 450mg / l, and the NaCl content is 2.4wt%. Multi-phase combined membrane bioreaction technology treats the COD to 49mg / l, and sends the water to the ammonia-soda method soda alkali salt process to salt for the ammonia-soda method soda ash production.
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The invention discloses a method for recycling saponification wastewater generated in process of producing epoxypropane by adopting a caustic soda saponification method. The method comprises the steps of: diluting sodium chloride-containing wastewater, which is generated in a process of producing epoxypropane by adopting the caustic soda saponification method, with reclaimed water, and treating the diluted sodium chloride-containing wastewater, wherein the treated sodium chloride-containing wastewater can be used as salt-melting water in a process of producing sodium carbonate by adopting an ammonia-soda process. Therefore, water resources and salt resources in the saponification wastewater can be comprehensively utilized, and brine purification cost in the process of producing sodium carbonate by adopting the ammonia-soda process can be lowered, the economic performance is increased, zero emission of wastewater during the production of epoxypropane by adopting a caustic soda saponification method is realized, and the influence on the environment is reduced.
Description
technical field [0001] The invention relates to a method for recycling industrial wastewater, in particular to a method for recycling propylene oxide saponification wastewater by caustic soda saponification. Background technique [0002] The caustic soda saponification process to produce propylene oxide will produce a large amount of wastewater rich in sodium chloride and high COD. If it is discharged outside, it will not only waste water and salt resources, but also cause serious environmental pollution. At present, the treatment method of caustic soda saponification method propylene oxide saponification waste water is electrolysis saponification waste water, obtains caustic soda solution and is reused in propylene oxide production, as the processing method that the patent No. is 200710011073.0, this method is that saponification waste water is reclaimed, five-effect evaporation concentrates, The caustic soda solution obtained by diaphragm method electrolysis is used for th...
Claims
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IPC IPC(8): C02F9/14C01D7/18
Inventor 迟庆峰何加海殷良诚吴中平朱荣振蔡巍张少飞张明昌雷宁董国良赵守军陈砚祥
Owner SHANDONG HAIHUA GRP CO LTD