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Zero-discharge cyclic utilization method for desulfurized wastewater of thermal power plant

A technology for thermal power plants and desulfurization wastewater, applied in gaseous effluent wastewater treatment, chemical instruments and methods, water/sewage treatment, etc., can solve the problems of flue system corrosion, limit the utilization of desulfurization wastewater in thermal power plants, etc., and achieve The effect of reducing pollution

Inactive Publication Date: 2018-02-27
NORTHWEST BRANCH OF CHINA DATANG CORP SCI & TECH RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, the known treatment methods for wet flue gas desulfurization wastewater from thermal power plants are carried out by chemical methods such as neutralization, flocculation, and precipitation, which can only remove heavy metal ions and suspended solids. - However, it has no ability to exclude, which limits the utilization of desulfurization wastewater in thermal power plants
Some thermal power plants also use the treatment method of injecting desulfurization wastewater into the flue through pipelines for evaporation, but this method has obvious defects. After the desulfurization wastewater is sprayed into the flue gas, it will cause serious corrosion to the flue system.
Therefore, the known above-mentioned methods focus on treatment and ignore utilization and are not advisable. In this way, a pollution-free recycling method that can not only effectively utilize thermal power plant desulfurization wastewater, but also enable zero discharge of this wastewater is urgently needed to be developed.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] (1) A pH adjustment tank with an alkali addition pipeline and a pH meter, a sedimentation tank with an alkali addition pipeline, and an evaporator are sequentially installed at the outlet of the desulfurization wastewater of the thermal power plant to be treated. The pH adjustment tank with alkali adding pipeline and pH meter is made of commercially available 8mm thick carbon steel plate, with a volume of 30m 3 The alkali-adding pipeline of the pH adjustment tank adopts a commercially available PVC dosing pipe with a diameter of 20 mm, and inserts the pipe into the middle and lower part of the pH adjustment tank body; the pH meter of the pH adjustment tank adopts a commercially available American polymetron 9135 type pH meter. The tank body of the sedimentation tank is also cut from 8mm thick carbon steel plate, with a volume of 40m 3 , the alkali-adding pipeline of this settling tank also adopts a commercially available PVC dosing pipe with a diameter of 20mm, and ins...

Embodiment 2

[0021] Steps (1) to (3) are the same as in Example 1;

[0022] (4) Using a conventional method, determine the process data of the evaporator according to the increase in the boiling point of the desulfurization wastewater containing salt and the increase in the evaporation boiling point of the desulfurization wastewater. The desulfurization wastewater treated in step (3) is injected into the evaporator set up in step (1) for evaporation and concentration in the following three stages. In the first stage, the temperature is controlled at 98-100°C and takes 140 minutes; in the second stage, the temperature is controlled at 74-78°C and it takes 120 minutes; in the third stage, the temperature is controlled at 50-54°C and it takes 180 minutes to evaporate Condensed water with a salt content of 3-5‰ produced by concentration can be directly used as boiler make-up water or power plant circulating water make-up water.

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PUM

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Abstract

The invention relates to the technical field of wastewater treatment and relates to a zero-discharge cyclic utilization method for desulfurized wastewater of a thermal power plant. The zero-dischargecyclic utilization method for the desulfurized wastewater of the thermal power plant, provided by the invention, comprises the steps: (1) arranging a pH regulating tank with an alkalizing pipe and a pH meter, a precipitation tank and an evaporator at a water outlet of the desulfurized wastewater to be treated of the thermal power plant; (2) injecting the desulfurized wastewater into the pH regulating tank to produce hydroxide precipitates of heavy metals; (3) injecting the hydroxide precipitates of heavy metals into the precipitation tank to produce insoluble salt precipitates of metals; (4) injecting the insoluble salt precipitates of metals into the evaporator, and implementing evaporation concentration in three stages, so as to obtain condensed water with the salt content of 0.3% to 0.5% for make-up water. The method provided by the invention has the following effects: 1) 80% to 90% of moisture of the desulfurized wastewater of the power plant can be evaporated, and the obtained condensed water can be fully recovered for make-up; for example, for a coal-burnt generator set of 2*600MW, 250,000 RMB is saved in one year; 2) boiler exhaust gas can be used without cost; 3) the pollution caused by the desulfurized wastewater is reduced, the total benefit is increased by 1.5 times or more, and meanwhile, byproducts can serve as chemical raw materials.

Description

technical field [0001] The invention belongs to the technical field of waste water treatment, and relates to a method for recycling desulfurization waste water of a thermal power plant with zero discharge. Background technique [0002] Among the various flue gas desulfurization processes at present, the limestone-gypsum wet flue gas desulfurization process has the advantages of mature technology, wide range of coal types and high desulfurization efficiency, and its application rate in actual projects is as high as 85%. Because the desulfurization wastewater produced by this process contains a large amount of soluble salts, suspended solids and heavy metal ions as well as high concentrations of chloride ions (Cl - ), high concentration fluoride ion (F - ) Harmful pollutants cannot be discharged directly, and need to be treated to meet the national environmental protection discharge standards before they can be discharged. [0003] However, the known treatment methods for we...

Claims

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Application Information

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IPC IPC(8): C02F9/10C02F103/18
CPCC02F1/04C02F1/5236C02F1/66C02F9/00C02F2103/18
Inventor 郭新茹盛丽雯姜波白公宝赵磊杜越
Owner NORTHWEST BRANCH OF CHINA DATANG CORP SCI & TECH RES INST