High-efficiency energy-saving sewage treatment method and device

Abstract

The invention discloses a method and device, which are used for harmlessly treating industrial sewage, can sufficiently utilize heat energy in the treatment process and can repeatedly utilize a water resource and other industrial products. The sewage treatment method comprises: first preheating to-be-treated sewage to a set temperature, then sending the sewage into an MVR evaporator, evaporating and concentrating the sewage to respectively obtain concentrated liquid and secondary steam, obtaining a treated solution when the concentration of concentrated liquid in the MVR evaporator reaches a predetermined value, introducing the treated solution into a forced circulating evaporator, and re-evaporating and concentrating the treated solution. By adopting the device, the method can be implemented, sewage can be effectively and efficiently treated, the off-line cleaning time of the device can be greatly shortened, the equipment is simpler to re-clean, and the equipment cost can be maximally reduced.

Description

technical field [0001] The invention relates to a method for harmless treatment of industrial sewage, especially for domestic or industrial high-salt wastewater and black liquor wastewater in the paper industry, and can make full use of the heat energy in the treatment process, and can be used for water resources and other industries. A method and device for reusing products. The method of the present invention adopts the method of mechanical forced circulation evaporation. After the sewage to be treated is preheated to the set temperature, it is sent to the MVR evaporator for evaporation and concentration, and the concentrated liquid and secondary steam are respectively obtained, and the MVR evaporator After the concentration of the concentrated liquid in the concentrated liquid reaches a predetermined value, the treated liquid is obtained. The treated liquid is introduced into the forced circulation evaporator for re-evaporation and concentration, and the concentrated liquid...

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Problems solved by technology

In fact, under this condition and state, the energy consumption required by the system is not much. On the contrary, the economic benefits and process conditions brought about are very considerable. However, the MVR evaporation system cannot further achieve the goal of enrichment

[0007] 2. Although a self-stripping device can be installed in the MVR evaporator, the secondary distillation condensate obtained by evaporation is discharged separately in the form of light-pollution condensate and heavy-pollution condensate. Usually, the COD content of the light-pollution condensate tank is between Below 350mg / L, it meets the use standard of industrial water, and can be used directly in the process; however, the COD content of heavily polluted condensate water is generally 4000mg / L or higher, which cannot meet the use standard of industrial water, and cannot be treated by MVR’s own evaporation system. It is processed in the next step, and it cannot realize the requirements of full reuse and zero discharge after treatment.

However, forced circulation evaporation often forms a self-contained multi-stage evaporation system, which uses the hierarchical relationship between the front and back and the end vacuum system to work, and it is difficult to organically combine and match with the MVR evaporation system in terms of temperature, pressure and energy balance.

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