Six-effect evaporative crystallization device and process applied to zero discharge of industrial wastewater

Abstract

The invention discloses a six-effect evaporative crystallization device and process applied to zero discharge of industrial wastewater. The six-effect evaporative crystallization device comprises six preheaters, six groups of evaporators, a desalting unit for desalination and other components, which are operated in series connection, wherein the front five preheaters focus on recovering waste heat of evaporative condensation water, and the preheater at the tail end is used for heating concentrated brine entering the first effect evaporator to close to a bubbling point; the front four effect evaporators are falling-film evaporators, the back two effect evaporators are forced circulation type evaporators, the front four effect evaporators are mainly used for evaporating water, the back two effect evaporators focus on concentration, and the brine is finally concentrated to a slurry with certain solid content; the slurry is desalinated by virtue of the desalting unit; and evaporated condensate exchanges heat with the concentrated brine to ensure that steam heat energy can be fully used, thereby improving the utilization ratio of the heat energy. The six-effect evaporative crystallization device can be widely applied to evaporative desalination working sections of various industries, and is particularly suitable for 'zero' discharge treatment systems for the industrial wastewater.

Description

technical field [0001] The invention belongs to the technical field of industrial wastewater treatment, and in particular relates to a six-effect evaporation crystallization process applied to zero discharge of industrial wastewater. Background technique [0002] Relevant national policies clearly require the promotion of waste water recycling in key industries such as iron and steel, electric power, chemical industry, and coal, and strive to achieve less or zero waste water discharge. In recent years, some places have also promulgated strict wastewater discharge standards. Sensitive river basins, regions and provinces with serious water pollution such as the Yellow River and Huaihe River do not even allow industrial enterprises to discharge wastewater into surface water bodies. Water resources and water environment problems have become the bottleneck restricting the development of the industry. Seeking wastewater treatment processes with better treatment effects, stronger ...

AI Technical Summary

Problems solved by technology

The first four effects of this invention are falling film evaporation. Due to the limitation of the minimum feed amount, the feed load is limited, and the falling film evaporator is easy to foul, the effect body is frequently cleaned, and the device cannot operate stably; the fifth and sixth effects The evaporation capacity is only about half of the first four effects. When the feed load is large, a large part of the secondary steam must be diverted to the sub-condenser, and there is no regulating valve on the diversion pipe, which makes the operation difficult and causes energy loss. , according to the economic definition, it can only be counted as five-effect evaporation; the six-effect discharge position is not suitable, and there is a risk of pipe blockage

[0006] At present, the "zero discharge" multi-effect evaporation of industrial wastewater in domestic enterprises mostly adopts three-effect evaporation + two-effect concentration and crystallization process. This method is relatively stable in operation, but because of its small number of effects, the heat utilization is not sufficient, and the economic effect is poor; And the evaporator generally adopts a forced circulation evaporator, which is large in size and high in cost; the comprehensive economy is poor

Images