Wastewater recycling process and device

Abstract

The invention relates to a wastewater recycling process and device. The process comprises the following process steps: carrying out single-effect distillation on high-salt, high-COD and dark-chroma wastewater obtained in a conventional cytosine synthesis process so as to obtain kettle residues and single-effect wastewater without inorganic salt; carrying out solid waste treatment on the kettle residues to obtain the residual single-effect wastewater; and diluting liquid caustic soda having a concentration of 30% and used in industrial production by using the single-effect wastewater instead ofpurified water so as to obtain liquid caustic soda having a concentration of 10%, adding the liquid caustic soda having a concentration of 10% into a neutralization procedure in the cytosine synthesis process for a neutralization reaction. The device is additionally provided with a wastewater single-effect distillation kettle and a single-effect wastewater storage tank, the wastewater single-effect distillation kettle communicates with a mixed alcohol recovery kettle, the wastewater single-effect distillation kettle communicates with the single-effect wastewater storage tank, and the single-effect wastewater storage tank communicates with a dilute alkali preparation kettle. According to the invention, a wastewater discharge amount and subsequent sewage treatment cost can be reduced, the preparation cost of the purified water can also be reduced, and resources are saved.

Description

technical field [0001] The invention belongs to the technical field of waste water recovery and treatment, and in particular relates to a waste water recovery and reuse process and device. Background technique [0002] In the existing cytosine synthesis process, acetonitrile, toluene and ethyl formate are generally mixed in a pre-mixing tank, and then the corresponding substances are added to increase the pressure through the autoclave, acidification tank, neutralization tank and extraction tank respectively. , acidification, neutralization and extraction to obtain a toluene layer and a water layer, the process is as follows figure 1 As shown, the toluene layer is rectified to obtain acetal, and the water layer is recovered through the mixed alcohol recovery tank to obtain mixed alcohol, and then the waste water is discharged. These waste water are usually high-salt, high-COD, and dark-color waste water, which must be evaporated by three effects After desalination, the wast...

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Problems solved by technology

[0002] In the existing cytosine synthesis process, acetonitrile, toluene and ethyl formate are generally mixed in a pre-mixing tank, and then the corresponding substances are added to increase the pressure through the autoclave, acidification tank, neutralization tank and extraction tank respectively. , acidification, neutralization and extraction to obtain a toluene layer and a water layer, the process is as follows figure 1 As shown, the toluene layer is rectified to obtain acetal, and the water layer is recovered through the mixed alcohol recovery tank to obtain mixed alcohol, and then the waste water is discharged. These waste water are usually high-salt, high-COD, and dark-color waste water, which must be evaporated by three effects After desalination, the waste water that reaches the standard can only be discharged after complex physical, chemical and biochemical sewage treatment processes. The cost of sewage treatment is high and water is wasted. In the process of neutralization, 10% dilute alkali needs to be added. In the industry, it is generally 30% liquid caustic soda, so the 10% dilute caustic obtained after mixing the 30% liquid caustic and purified water in the industry needs to be added to the neutralization tank for neutralization reaction, and the production of purified water needs to be carried out Four-stage reverse osmosis and other processes to remove inorganic salts, high production cost and troublesome operation

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