Nuclear power plant seawater desalination concentrated water and non-radioactive wastewater combined treatment control method and control system

Abstract

The invention provides a combined treatment control method and control system for seawater desalination concentrated water and non-radioactive wastewater of a nuclear power plant, belongs to the field of water treatment of the nuclear power plant, and can solve the problem that the seawater desalination concentrated water and non-radioactive wastewater of the nuclear power plant are diluted and then discharged to the sea, so that negative effects can be generated on the marine environment due to long-term discharge of concentrated point locations. The control method comprises the following steps: S1, performing pressure reduction treatment on high-pressure reverse osmosis concentrated seawater generated by a seawater desalination system of the nuclear power plant; s2, performing electrolytic treatment on the concentrated seawater subjected to pressure reduction treatment to obtain a sodium hypochlorite mixed solution, and storing the sodium hypochlorite mixed solution; s3, the sodium hypochlorite mixed solution is added into the non-radioactive wastewater, sodium hypochlorite and ammonia nitrogen in the non-radioactive wastewater are subjected to an oxidation-reduction reaction, and treated wastewater is obtained; and S4, after the measured value of the ammonia nitrogen concentration in the wastewater treated in the step S3 meets the emission standard, carrying out emission treatment. The method can be applied to wastewater treatment of a nuclear power plant, and resource utilization of reverse osmosis concentrated seawater and harmless treatment of non-radioactive wastewater are realized.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment in nuclear power plants, and in particular relates to a combined treatment control method and control system for desalination concentrated water and non-radioactive waste water in nuclear power plants. Background Art

[0003] Both reverse osmosis concentrated water and high ammonia nitrogen wastewater are discharged into the sea after being diluted, but long-term discharge at concentrated points will still have a negative impact on the marine environment and marine ecosystem over time. Therefore, providing a more environmentally friendly method for treating reverse osmosis concentrated water and high ammonia nitrogen wastewater from nuclear power plants is an urgent problem to be solved in the industry. Summary of the invention

[0004] The present invention aims at the technical problem that in the prior art, desalination concentrated water and non-radioactive wastewater of nuclear power plants are discharged into the sea after being diluted, which has a negative impact on the marine environment and marine ecosystem due to long-term discharge at concentrated points. The present invention proposes a combined treatment method and control system for desalination concentrated water and non-radioactive wastewater of nuclear power plants, which utilizes concentrated seawater through reverse osmosis as a resource and treats non-radioactive wastewater harmlessly. The discharge of high-concentration seawater and ammonia nitrogen pollutants is greatly reduced, and the environmental benefits are remarkable. In addition, the system operation can be monitored in real time, and has strong self-regulation ability and good adaptability.

[0005] In order to achieve the above-mentioned object, the technical scheme adopted by the present invention is: a combined treatment control method for desalination concentrated water and non-radioactive wastewater of a nuclear power plant, comprising the following steps: S1, decompressing the high-pressure reverse osmosis concentrated seawater produced by the desalination system of the nuclear power plant; S2, electrolyzing the concentrated seawater after the decompression treatment to obtain a sodium hypochlorite mixed solution and storing it; S3, adding the sodium hypochlorite mixed solution to the non-radioactive wastewater to cause the sodium hypochlorite to undergo an oxidation-reduction reaction with the ammonia nitrogen in the non-radioactive wastewater to obtain treated wastewater; S4, after the measured ammonia nitrogen concentration value in the treated wastewater in step S3 meets the discharge standard, the wastewater is discharged.

[0006] In some of the embodiments, in step S1, the high-pressure reverse osmosis concentrated seawater is decompressed to a pressure of 0.15-0.20 MPa.

[0007] In some embodiments, the dosage of the sodium hypochlorite mixed solution in step S3 satisfies Q=6.58k×a×q / c, where Q represents the quantitative dosage of sodium hypochlorite, in units of m 3 / h; k is the dosage coefficient, which ranges from 1.1 to 1.2; a is the ammonia nitrogen concentration at the non-radioactive wastewater inlet, in mg / L; q is the flow rate of non-radioactive wastewater, in m 3 / h; c represents the effective chlorine concentration in the sodium hypochlorite storage module, in mg / L.

[0008] In some embodiments, the redox reaction time in step S3 is 50 to 60 minutes.

[0009] In some of the embodiments, in step S4, the ammonia nitrogen concentration in the wastewater is measured by a drainage ammonia nitrogen analyzer. When the measured value is less than or equal to the emission limit, the emission standard is met, and the control program opens the automatic discharge valve and closes the automatic reflux valve to discharge the wastewater with ammonia nitrogen concentration that meets the standard; when the measured value is greater than the emission limit, the control program closes the automatic discharge valve and opens the automatic reflux valve to return the wastewater with ammonia nitrogen concentration that does not meet the standard to the system for circulation treatment, and controls the increase in the dosage of the sodium hypochlorite mixed solution.

[0010] On the other hand, the present invention also provides a combined treatment control system for seawater desalination concentrated water and non-radioactive wastewater in a nuclear power plant, comprising a decompression treatment module, which decompresses the high-pressure reverse osmosis concentrated seawater produced by the seawater desalination system of the nuclear power plant; an electrolysis treatment module, which electrolyzes the concentrated seawater after the decompression treatment; a sodium hypochlorite storage module, which stores the sodium hypochlorite mixed solution obtained by the electrolysis treatment; a chlorination module, which controls the amount of sodium hypochlorite added to the non-radioactive wastewater; an oxidation-reduction treatment module, which performs an oxidation-reduction reaction between the sodium hypochlorite and the ammonia nitrogen in the non-radioactive wastewater; an online instrument detection module, which measures various parameters in the control system and transmits them to the control system in real time for detection information conversion; an automatic control valve module, which controls the switching of various valves in the system; and a system operation control module, which controls the automatic operation of the system.

[0011] In some of the embodiments, the online instrument detection module includes a liquid level meter for measuring the liquid level in the sodium hypochlorite storage module; an effective chlorine analyzer for detecting the effective chlorine concentration in the sodium hypochlorite storage module; an inlet ammonia nitrogen analyzer for detecting the ammonia nitrogen concentration at the inlet of non-radioactive wastewater; a flow meter for detecting the flow rate of non-radioactive wastewater; and a drainage ammonia nitrogen analyzer for detecting the ammonia nitrogen concentration at the outlet of non-radioactive wastewater.

[0012] In some of the embodiments, the automatic control valve module includes an inlet automatic valve for controlling the entry of reverse osmosis concentrated seawater after decompression treatment into the system; a discharge automatic valve for controlling the discharge of non-radioactive wastewater with ammonia nitrogen concentration that meets the standard; and a reflux automatic valve for controlling the reflux of non-radioactive wastewater with ammonia nitrogen concentration that does not meet the standard to the control system for circulation treatment.

[0013] In some of the embodiments, the system operation control module collects, analyzes and interlocks data on the drainage ammonia nitrogen analyzer, the discharge automatic valve, the reflux automatic valve and the chlorination module respectively. When the measured ammonia nitrogen concentration value at the non-radioactive wastewater outlet is less than or equal to the discharge standard, the discharge automatic valve is opened, the reflux automatic valve is closed, and the dosage of sodium hypochlorite remains unchanged; when the measured ammonia nitrogen concentration value at the non-radioactive wastewater outlet is greater than the discharge standard, the discharge automatic valve is closed, the reflux automatic valve is opened, and the wastewater with substandard ammonia nitrogen concentration is refluxed to the system for circulation treatment, and the dosage of sodium hypochlorite is increased.

[0014] In some of the embodiments, the system operation control module interlocks the water inlet automatic valve with the liquid level meter in the sodium hypochlorite storage module, and controls the automatic closing or opening of the water inlet automatic valve according to the height of the storage liquid level; the system operation control module interlocks the water inlet automatic valve with the electrolysis treatment, and controls the start or end of the electrolysis treatment according to the opening or closing of the water inlet automatic valve.

[0015] Compared with the prior art, the advantages and positive effects of the present invention are:

[0016] The present invention can realize the resource utilization of reverse osmosis concentrated seawater in nuclear power plants and the harmless treatment of non-radioactive wastewater, greatly reducing the discharge of high-concentration seawater and ammonia nitrogen pollutants, and having significant environmental benefits; compared with raw seawater, the reverse osmosis concentrated seawater is produced through a seawater desalination system, has a higher chloride ion concentration, less impurities, high electrolytic treatment current efficiency, energy saving, and high effective chlorine production; the control system of the present invention can monitor operation in real time, has strong self-regulation ability, and good adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The present invention provides a process flow chart and a signal control program chart for the combined treatment of seawater desalination concentrate and non-radioactive wastewater in a nuclear power plant. DETAILED DESCRIPTION

[0018] In order to be able to understand the characteristics and technical contents of the embodiments of the present invention in more detail, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the embodiments described below are only part of the embodiments of the present invention, rather than all the embodiments of the present invention. In the following technical description, for the convenience of explanation, a full understanding of the disclosed embodiments is provided through multiple details. However, one or more embodiments can still be implemented without these details. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection requested by the present invention.

[0019] The combined treatment control method and control system for seawater desalination concentrated water and non-radioactive wastewater in a nuclear power plant provided by the embodiment of the present invention can realize the resource utilization of reverse osmosis concentrated seawater in a nuclear power plant and the harmless treatment of non-radioactive wastewater, realize the organic combination of the two, achieve the function and effect of synchronous purification, greatly reduce the discharge of high-concentration seawater and ammonia nitrogen pollutants, and have significant environmental benefits; compared with the original seawater, the reverse osmosis concentrated seawater is produced through the seawater desalination system, has a higher chloride ion concentration, less impurities, high electrolytic treatment current efficiency, energy saving, and high effective chlorine production; the control system of the present invention can monitor the operation in real time, has strong self-regulation ability, and good adaptability.

[0020] Figure 1 The process flow and signal control program diagram for the combined treatment of seawater desalination concentrated water and non-radioactive wastewater in a nuclear power plant provided by the embodiment of the present invention are shown in FIG. Figure 1 As shown, the combined treatment control method of seawater desalination concentrated water and non-radioactive wastewater in a nuclear power plant of the present invention comprises the following steps:

[0021] S1. Open the automatic water inlet valve to decompress the high-pressure reverse osmosis concentrated seawater produced by the nuclear power plant's seawater desalination system. After the pressure drops to 0.15-0.20Mpa, it enters the system through the automatic water inlet valve;

[0022] S2, electrolyzing the concentrated seawater after the decompression treatment to obtain a sodium hypochlorite mixed solution and storing it in a sodium hypochlorite storage tank, monitoring the liquid level in the sodium hypochlorite storage tank in real time by a liquid level meter, measuring the effective chlorine concentration c in the sodium hypochlorite mixed solution by an effective chlorine analyzer, and feeding back the above measurement data to the control system in real time;

[0023] S3. The non-radioactive wastewater is respectively tested by a flow meter to measure the flow rate q of the non-radioactive wastewater, and the inlet ammonia nitrogen analyzer is used to measure the ammonia nitrogen concentration a at the inlet of the non-radioactive wastewater, and the results are fed back to the control system and the test information is converted, and then a sodium hypochlorite mixed solution is added to the non-radioactive wastewater to make the sodium hypochlorite react with the ammonia nitrogen in the non-radioactive wastewater to generate nitrogen gas for discharge, thereby reducing the ammonia nitrogen concentration in the non-radioactive wastewater to obtain treated wastewater, wherein the reaction time is 50 to 60 minutes, and the dosage of the sodium hypochlorite mixed solution satisfies Q=6.58k×a×q / c,

[0024] In the formula, Q represents the quantitative dosage of sodium hypochlorite, unit: m 3 / h; k is the dosage coefficient, which ranges from 1.1 to 1.2; a is the ammonia nitrogen concentration at the non-radioactive wastewater inlet, in mg / L; q is the flow rate of non-radioactive wastewater, in m 3 / h; c represents the effective chlorine concentration in the sodium hypochlorite storage module, in mg / L;

[0025] S4. The wastewater treated in step S3 is measured for ammonia nitrogen concentration b at the non-radioactive wastewater outlet by a discharge ammonia nitrogen analyzer. When the measured value is less than or equal to the discharge limit, the control program opens the discharge automatic valve and closes the reflux automatic valve to discharge the wastewater with ammonia nitrogen concentration that meets the standard; when the measured value is greater than the discharge limit, the control program closes the discharge automatic valve and opens the reflux automatic valve to return the wastewater with ammonia nitrogen concentration that does not meet the standard to the system for circulation treatment, and controls the increase in the dosage of the sodium hypochlorite mixed solution.

[0026] The combined treatment control system of seawater desalination concentrated water and non-radioactive wastewater in a nuclear power plant of the present invention is used to realize the combined treatment control method of seawater desalination concentrated water and non-radioactive wastewater in a nuclear power plant, and the control system comprises: a decompression treatment module, which performs decompression treatment on high-pressure reverse osmosis concentrated seawater generated by a seawater desalination system of a nuclear power plant; an electrolysis treatment module, which performs electrolysis treatment on concentrated seawater after decompression treatment; a sodium hypochlorite storage module, which stores a sodium hypochlorite mixed solution obtained by electrolysis treatment; a chlorination module, which controls the dosage of sodium hypochlorite added to non-radioactive wastewater; an oxidation-reduction treatment module, which performs oxidation-reduction reaction between sodium hypochlorite and ammonia nitrogen in non-radioactive wastewater; an online instrument detection module, which measures various parameters in the control system and transmits them to the control system in real time for detection information conversion; an automatic control valve module, which controls the switches of various valves in the system; and a system operation control module, which controls the automatic operation of the system.

[0027] The online instrument detection module of the combined treatment control system of seawater desalination concentrated water and non-radioactive wastewater in a nuclear power plant of the present invention comprises a liquid level meter for measuring the liquid level in a sodium hypochlorite storage module; an effective chlorine analyzer for detecting the effective chlorine concentration in the sodium hypochlorite storage module; an inlet ammonia nitrogen analyzer for detecting the ammonia nitrogen concentration at an inlet of non-radioactive wastewater; a flow meter for detecting the flow of non-radioactive wastewater; and a drainage ammonia nitrogen analyzer for detecting the ammonia nitrogen concentration at an outlet of non-radioactive wastewater.

[0028] The automatic control valve module of the combined treatment control system of seawater desalination concentrated water and non-radioactive wastewater in a nuclear power plant of the present invention comprises an automatic water inlet valve for controlling the reverse osmosis concentrated seawater after decompression treatment to enter the system; an automatic discharge valve for controlling the discharge of non-radioactive wastewater with ammonia nitrogen concentration that meets the standard; and an automatic reflux valve for controlling the non-radioactive wastewater with ammonia nitrogen concentration that does not meet the standard to flow back to the control system for circulation treatment.

[0029] The system operation control module of the combined treatment control system of seawater desalination concentrated water and non-radioactive wastewater of a nuclear power plant of the present invention respectively collects, analyzes and interlocks data on a drainage ammonia nitrogen analyzer, a discharge automatic valve, a reflux automatic valve and a chlorination module; when the measured ammonia nitrogen concentration value at the non-radioactive wastewater outlet is less than or equal to the discharge standard, the discharge automatic valve is opened, the reflux automatic valve is closed, and the dosage of sodium hypochlorite remains unchanged; when the measured ammonia nitrogen concentration value at the non-radioactive wastewater outlet is greater than the discharge standard, the discharge automatic valve is closed, the reflux automatic valve is opened, the wastewater with substandard ammonia nitrogen concentration is refluxed to the system for circulation treatment, and the dosage of sodium hypochlorite is increased.

[0030] The system operation control module of the combined treatment control system of seawater desalination concentrated water and non-radioactive wastewater of a nuclear power plant of the present invention performs interlocking control on the water inlet automatic valve and the liquid level gauge in the sodium hypochlorite storage module, and controls the automatic closing or opening of the water inlet automatic valve according to the height of the storage liquid level; the system operation control module performs interlocking control on the water inlet automatic valve and the electrolysis treatment, and controls the start or end of the electrolysis treatment according to the opening or closing of the water inlet automatic valve.

[0031] In order to more clearly and in detail introduce the combined treatment control method and control system for seawater desalination concentrate and non-radioactive wastewater in a nuclear power plant provided by the embodiments of the present invention, a description will be given below in conjunction with specific embodiments.

[0032] Example 1

[0033] A nuclear power plant collects high-pressure reverse osmosis concentrated seawater produced by the seawater desalination system and electrolyzes it, and quantitatively adds sodium hypochlorite produced by the electrolysis of concentrated seawater to the non-radioactive wastewater of the nuclear power plant, so that the ammonia nitrogen in the non-radioactive wastewater is removed after a redox reaction with sodium hypochlorite. After treatment, the ammonia nitrogen in the discharged water meets the first-level standard of the second period in Guangdong Province's "Water Pollution Emission Limits" (DB 44 / 26-2001) of ≤10mg / L.

[0034] The specific steps of the combined treatment control method of seawater desalination concentrated water and non-radioactive wastewater in a nuclear power plant in this embodiment are as follows:

[0035] The high-pressure reverse osmosis concentrated seawater produced by the seawater desalination system is depressurized to 0.15MPa and then electrolyzed to produce sodium hypochlorite with an effective chlorine concentration of 2500mg / L;

[0036] The above sodium hypochlorite was added into non-radioactive wastewater for reaction. The ammonia nitrogen content in the non-radioactive wastewater was 240 mg / L. The dosage of sodium hypochlorite was 23 mg / L. 3 / h, non-radioactive wastewater treatment capacity is 30m 3 / h, the redox treatment time is 1h;

[0037] After the above oxidation-reduction reaction, the ammonia nitrogen concentration in the discharged wastewater is ≤8.3mg / L.

[0038] It can be seen from the above embodiments that the combined treatment control method and system for desalination concentrated water and non-radioactive wastewater of nuclear power plants provided by the present invention can realize the resource utilization of reverse osmosis concentrated seawater of nuclear power plants and the harmless treatment of non-radioactive wastewater, greatly reducing the discharge of high-concentration seawater and ammonia nitrogen pollutants, and having significant environmental benefits.

[0039] Finally, it should be noted that the present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only the preferred feasible embodiments of the present invention, and the above-mentioned embodiments are only used to illustrate the technical scheme of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations, modifications, evolutions and improvements made by ordinary technicians in this field to the technical scheme of the present invention should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A combined treatment control method for desalination concentrated water and non-radioactive wastewater in a nuclear power plant, characterized in that: The following steps are involved: S1. Decompression treatment of high-pressure reverse osmosis concentrated seawater produced by the nuclear power plant's seawater desalination system; S2, electrolyzing the concentrated seawater after the decompression treatment to obtain a sodium hypochlorite mixed solution and storing it; S3, adding the sodium hypochlorite mixed solution into the non-radioactive wastewater to cause the sodium hypochlorite to undergo an oxidation-reduction reaction with ammonia nitrogen in the non-radioactive wastewater to obtain treated wastewater; S4. After the measured ammonia nitrogen concentration in the wastewater treated in step S3 meets the discharge standard, discharge treatment is performed.

2. The combined treatment control method for desalination concentrated water and non-radioactive wastewater of a nuclear power plant according to claim 1 is characterized in that: In step S1, the high-pressure reverse osmosis concentrated seawater is decompressed to a pressure of 0.15-0.20 MPa.

3. The combined control and treatment method for desalination concentrated water and non-radioactive wastewater of a nuclear power plant according to claim 1, characterized in that: The dosage of the sodium hypochlorite mixed solution in step S3 satisfies Q=6.58k×a×q / c, In the formula, Q represents the quantitative dosage of sodium hypochlorite, unit: m 3 / h; k is the dosage coefficient, which ranges from 1.1 to 1.2; a is the ammonia nitrogen concentration at the non-radioactive wastewater inlet, in mg / L; q is the flow rate of non-radioactive wastewater, in m 3 / h; c represents the effective chlorine concentration in the sodium hypochlorite storage module, in mg / L.

4. The combined treatment control method for desalination concentrated water and non-radioactive wastewater of a nuclear power plant according to claim 1, characterized in that: The redox reaction time in step S3 is 50 to 60 minutes.

5. The combined treatment control method for desalination concentrated water and non-radioactive wastewater of a nuclear power plant according to claim 1, characterized in that: In step S4, the ammonia nitrogen concentration in the wastewater is measured by the drainage ammonia nitrogen analyzer. When the measured value is less than or equal to the emission limit, the emission standard is met, and the control program opens the automatic discharge valve and closes the automatic reflux valve at the same time to discharge the wastewater with ammonia nitrogen concentration that meets the standard; when the measured value is greater than the emission limit, the control program closes the automatic discharge valve and opens the automatic reflux valve at the same time to return the wastewater with ammonia nitrogen concentration that does not meet the standard to the system for circulation treatment, and controls the increase in the dosage of the sodium hypochlorite mixed solution.

6. A combined treatment control system for desalination concentrated water and non-radioactive wastewater in a nuclear power plant, used to implement the combined treatment control method for desalination concentrated water and non-radioactive wastewater in a nuclear power plant as claimed in any one of claims 1 to 5, characterized in that: It includes a decompression treatment module, which decompresses the high-pressure reverse osmosis concentrated seawater produced by the nuclear power plant's seawater desalination system; an electrolysis treatment module, which electrolyzes the concentrated seawater after decompression treatment; a sodium hypochlorite storage module, which stores the sodium hypochlorite mixed solution obtained by electrolysis treatment; a chlorination module, which controls the amount of sodium hypochlorite added to the non-radioactive wastewater; and a redox treatment module, in which the sodium hypochlorite undergoes redox reaction with ammonia nitrogen in the non-radioactive wastewater. The online instrument detection module measures various parameters in the control system and transmits them to the control system in real time for detection information conversion; the automatic control valve module controls the switching of various valves in the system; the system operation control module controls the automatic operation of the system.

7. The combined treatment control system for desalination concentrated water and non-radioactive wastewater of a nuclear power plant according to claim 6, characterized in that: The online instrument detection module includes a liquid level meter for measuring the liquid level in the sodium hypochlorite storage module; an effective chlorine analyzer for detecting the effective chlorine concentration in the sodium hypochlorite storage module; an inlet ammonia nitrogen analyzer for detecting the ammonia nitrogen concentration at the inlet of non-radioactive wastewater; and a flow meter for detecting the flow of non-radioactive wastewater. Drainage ammonia nitrogen analyzer is used to detect the ammonia nitrogen concentration at the outlet of non-radioactive wastewater.

8. The combined treatment control system for desalination concentrated water and non-radioactive wastewater of a nuclear power plant according to claim 6, characterized in that: The automatic control valve module includes an inlet automatic valve for controlling the entry of reverse osmosis concentrated seawater after decompression treatment into the system; a discharge automatic valve for controlling the discharge of non-radioactive wastewater with ammonia nitrogen concentration that meets the standard; and a reflux automatic valve for controlling the reflux of non-radioactive wastewater with ammonia nitrogen concentration that does not meet the standard to the control system for circulation treatment.

9. The combined treatment control system for desalination concentrated water and non-radioactive wastewater of a nuclear power plant according to claim 6, characterized in that: The system operation control module collects, analyzes and interlocks data on the wastewater ammonia nitrogen analyzer, the discharge automatic valve, the reflux automatic valve and the chlorination module. When the measured ammonia nitrogen concentration at the non-radioactive wastewater outlet is less than or equal to the discharge standard, the discharge automatic valve opens, the reflux automatic valve closes, and the amount of sodium hypochlorite added remains unchanged. When the measured ammonia nitrogen concentration at the non-radioactive wastewater outlet is greater than the discharge standard, the automatic discharge valve is closed and the automatic reflux valve is opened to return the wastewater with substandard ammonia nitrogen concentration to the system for circulation treatment, and increase the dosage of sodium hypochlorite.

10. The combined treatment control system for desalination concentrated water and non-radioactive wastewater of a nuclear power plant according to claim 6, characterized in that: The system operation control module performs interlocking control on the water inlet automatic valve and the liquid level gauge in the sodium hypochlorite storage module, and controls the automatic closing or opening of the water inlet automatic valve according to the high and low storage liquid levels; the system operation control module performs interlocking control on the water inlet automatic valve and the electrolysis treatment, and controls the start or end of the electrolysis treatment according to whether the water inlet automatic valve is opened or closed.

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