CN104030498B - A kind of electric power plant circulating water parallel seismic method method - Google Patents

Abstract

The invention discloses a side-flow treatment method of circulating water in a power plant, which belongs to the technical field of sterilizing treatment of circulating water in a power plant. The ultrafiltration effluent is sent to the nanofiltration for treatment; the obtained non-hardness nanofiltration product water is sent to the electrolytic cell as the electrolyte for electrolysis to produce sodium hypochlorite, and the available chlorine in the produced water after electrolysis is controlled by adjusting the flow rate of the electrolyte and the electrolysis voltage. The content reaches more than 100mg/L; finally, the obtained hardness-free aqueous solution containing sodium hypochlorite is returned to the circulating water. The method of the present invention utilizes the characteristics of high water temperature and high salt content of the circulating water to electrolyze the circulating water to produce sodium hypochlorite. The circulating water system realizes continuous sterilization treatment of circulating water, effectively reducing the impact of microbial growth on the circulating water system.

Description

A method for treating the bypass flow of circulating water in a power plant

technical field

The invention relates to a sterilization treatment technology for a circulating water system of a power plant, in particular to a side-flow treatment method for the circulating water of a power plant.

technical background

The circulating water system of the power plant is the system with the largest water consumption in the power plant. Since the temperature of the circulating water is in the range of 10-40 ℃ all year round, and it is sunny and rich in nutrients, it is a favorable environment for the growth and reproduction of bacteria. The scaling, corrosion and Microbial growth is the main problem faced by circulating water systems for a long time. In order to reduce the risk of fouling in the circulating water system, the concentration ratio of circulating water must be strictly controlled, and part of the circulating water shall be discharged as sewage; in order to reduce the impact of microbial growth in the circulating water, it is necessary to regularly sterilize the circulating water. The treatment is carried out by adding fungicides to circulating water, but the addition of fungicides is generally intermittent and not continuous, and there are problems such as untimely dosing, insufficient dosage, and too long dosing intervals, resulting in poor bactericidal effects, etc. question.

Contents of the invention

The technical problem to be solved by the invention is to provide a side-flow treatment method of circulating water in a power plant, which has good bactericidal effect and can effectively increase the concentration ratio of circulating water.

In order to solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for treating the bypass flow of circulating water in a power plant, the key technology of which is: the steps of the method are as follows:

1) Send the circulating water to the multi-media filter for filtration, so that the turbidity of the filtered water is below 5NTU;

2) Send the filtered water obtained in step (1) to ultrafiltration for treatment, and control the water recovery rate of ultrafiltration to 80%-95%;

3) Send the ultrafiltration effluent obtained in step (2) into the nanofiltration for treatment, adjust the pH value of the nanofiltration influent to 6.0-8.0, and control the nanofiltration water recovery rate to 70%-90%;

4) Send the non-hardness nanofiltration product water obtained in step (3) as the electrolyte into the electrolytic cell for electrolysis to produce sodium hypochlorite, and control the available chlorine content of the product water after electrolysis to 100mg by adjusting the flow rate of the electrolyte and the electrolysis voltage /L above;

5) returning the hardness-free aqueous solution containing sodium hypochlorite obtained in step (4) to the circulating water;

The supplementary circulating water of the power plant is surface water, ground water or urban reclaimed water.

A part of the hardness-free aqueous solution containing sodium hypochlorite obtained in step 4) is used for periodic sterilization treatment by ultrafiltration.

The step 4) is specifically: when the nanofiltration water without hardness is sent into the electrolytic cell as the electrolyte for electrolysis to produce sodium hypochlorite, the output of available chlorine in the water after electrolysis is controlled by adjusting the flow rate of the electrolyte and the electrolysis voltage to make the circulating water The amount of residual chlorine can meet the sterilization requirements of circulating water in different seasons. When the microbial growth in circulating water is not serious, the electrolyte can be reduced, and even the electrolytic cell can be run intermittently, and the nanofiltration water can be directly returned to the circulating water.

The beneficial effect that the present invention obtains by adopting above-mentioned technical scheme is as follows:

(1) The method of the present invention utilizes the characteristics of high water temperature and high salt content of circulating water to electrolyze the circulating water to produce sodium hypochlorite. Replenish to the circulating water system without introducing foreign impurities, and realize continuous sterilization treatment of circulating water, effectively reducing the impact of microbial growth on the circulating water system.

(2) The method of the present invention makes full use of the characteristics that nanofiltration can recover monovalent ions and has a good removal effect on divalent ions and organic matter, and purify monovalent salts such as sodium chloride and potassium chloride in circulating water for electrolysis Chlorine, and remove calcium, magnesium, sulfate, organic matter and other harmful substances in circulating water that are likely to cause scaling and fouling in circulating water, which can effectively increase the concentration ratio of circulating water, reduce the amount of sewage discharged from circulating water, and effectively save water resources.

detailed description

Example 1

(1) Extract the circulating water from the circulating water tower of the power plant, and send it to the multi-media filter for filtration at a flow rate of 100m ³ /h. The diameter of the multi-media filter is Φ3200, the layer height is 1200mm, of which the quartz sand is 800mm, The anthracite is 400mm, and the output of a single multimedia filter is 50 m ³ /h. The turbidity of the effluent is less than 5NTU. The water quality of circulating water in the power plant is shown in Table 1.

Table 1 Circulating water quality

(2) Send the effluent from the filter in step (1) to ultrafiltration for treatment. The membrane element of the ultrafiltration is an external pressure ultrafiltration membrane, the recovery rate is 90%, and the SDI of the ultrafiltration effluent is less than 4.0.

(3) Add hydrochloric acid to adjust the pH value of the ultrafiltration water obtained in step (2) to 6.0-6.5, and send it to nanofiltration for treatment. The nanofiltration is one stage and two stages, and the recovery rate is 75%. The divalent ions in the nanofiltration product water have all been removed, and the monovalent ions have been concentrated. The water quality is shown in Table 2.

Table 2 Water quality of nanofiltration product water

(4) Send the ultrafiltration product water obtained in step ( ³ ) into the electrolytic cell for electrolysis. The cell voltage is 180V, the available chlorine content of the electrolyte is 120-140mg/L, and the temperature rise of the electrolyte after electrolysis is 2-4°C.

(5) returning the hardness-free aqueous solution containing sodium hypochlorite obtained in step (4) to circulating water;

After 120 hours of continuous bypass treatment, the residual chlorine content in the circulating water has reached above 0.5 mg/L, which has a good bactericidal effect. The effluent after the bypass has no hardness and sulfate radicals, which is beneficial to further increase the concentration ratio of circulating water.

Claims (1)

1. A power plant circulating water bypass treatment method is characterized in that: the method steps are as follows: 1) Send the circulating water to the multi-media filter for filtration, so that the turbidity of the filtered water is below 5NTU; 2) Send the filtered water obtained in step (1) to ultrafiltration for treatment, and control the water recovery rate of ultrafiltration to 80%-95%; 3) Send the ultrafiltration effluent obtained in step (2) into the nanofiltration for treatment, adjust the pH value of the nanofiltration influent to 6.0-8.0, and control the nanofiltration water recovery rate to 70%-90%; 4) Send the non-hardness nanofiltration product water obtained in step (3) into the electrolytic cell as the electrolyte for electrolysis to produce sodium hypochlorite, and control the output of available chlorine in the product water after electrolysis to 100mg by adjusting the flow rate of the electrolyte and the electrolysis voltage /L above; 5) returning the hardness-free aqueous solution containing sodium hypochlorite obtained in step (4) to the circulating water; The circulating water replenishment of the power plant is surface water, ground water or urban reclaimed water; A part of the hardness-free aqueous solution containing sodium hypochlorite obtained in step 4) is used for periodic sterilization treatment by ultrafiltration.