Power plant wastewater zero-discharge treatment technique

Abstract

The invention discloses a power plant wastewater zero-discharge treatment technique which comprises a pretreatment process, an evaporative concentration process and an evaporative crystallization process, wherein the pretreatment process equipment comprises a precipitation and concentration tank, a sludge dewatering machine, and a raw water precipitation tank, a primary softening reactor, a secondary softening reactor and a softening precipitation tank which are sequentially connected; the evaporative concentration process equipment comprises an automatic back flush filter, a plate-type preheater, a degasser and a falling film evaporator which are sequentially communicated; and the evaporative crystallization process equipment comprises a concentrated solution tank, a crystallizing heater and a crystallizer which are sequentially communicated. The desulfurization water treatment technique is reasonable in step design and performs the pretreatment, evaporative concentration and evaporative crystallization on the desulfurization wastewater, and the end products are only distilled water and crystalline salt, thereby reducing the discharge of the harmful substances, lowering the energy consumption and implementing the goal of zero discharge of desulfurization wastewater.

Description

technical field [0001] The invention relates to the environmental protection industry, in particular to a zero-discharge treatment process for power plant desulfurization wastewater and other high-salinity, high-hardness industrial wastewater. Background technique [0002] "Zero discharge" is defined as industrial and mining enterprises do not discharge any waste water to the environment, and all industrial waste water is reused. With the increasing degree of industrialization, the discharge of industrial water and wastewater is also increasing, and the harm to the ecological environment is also becoming more serious. At the same time, severe water shortage in some areas has become a constraint on the sustainable development of social economy. Faced with such a severe situation, some industrially developed countries have implemented "zero discharge" of wastewater for industrial and mining enterprises in certain areas. [0003] At present, the treatment methods for desu...

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Problems solved by technology

[0004] The chemical softening + ultrafiltration + reverse osmosis method has high requirements on the hardness, suspended solids, salinity, turbidity and other indicators of the influent water quality, high pre-treatment requirements and complicated processes; the product has a short service life and high replacement costs; Osmosis can only recover about 60% of the wastewater, and the concentrated water still needs to be treated by other methods, which cannot meet the requirements of zero discharge

[0005] The main problem of the chemical softening + multi-effect evaporation method is: the hardness of the wastewater after chemical softening is generally 20-300mg / L (calculated as CaCO3). Phosphate, etc. will gradually crystallize out and adhere to the evaporation wall, which will form serious scaling in the evaporator and pipeline process

According to practice, under this condition, the evaporator needs to be shut down for cleaning after 2 to 4 months of operation, resulting in uncontinuous production; compared with single-effect evaporation, the steam consumption of multi-effect evaporation is reduced, but with Domestic steam prices have risen, and process operation costs are still high; fresh steam needs to be continuously added to the operation process, and for some enterprises without surplus steam, additional steam supply is required to increase project construction costs

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