Nuclear waste liquid evaporator boron concentration adjusting method based on liquid level forced control

Abstract

The invention belongs to the technical field of third-generation nuclear power operation, and relates to a nuclear waste liquid evaporator boron concentration adjusting method based on liquid level forced control, which comprises the following steps: (1) chemical sampling confirms that the boron concentration in an evaporator is 38000 ppm, and the boron concentration needs to be adjusted; (2) forcing the liquid level of the evaporator to be 1600mm; (3) operating and starting the evaporator to a state 5, wherein the state 5 indicates that the treated waste liquid is changed into concentrated liquid; (4) after the evaporator is started to the state 5, the feeding valve is closed manually immediately; (5) starting timing after the distillate discharge flow meter is read; (6) stopping the evaporator; (7) chemically sampling the boron concentration of the evaporator; (8) if the sampling does not reach the target boron concentration, repeatedly executing the steps (3), (4), (5), (6) and (7); (9) if the sampling reaches the target boron concentration, the forced signal is required to be recovered; and (10) arranging concentrated solution discharge. According to the invention, the dual goals of accurate regulation and control of boron concentration and cost control in the waste liquid treatment process of the nuclear power station are accurately met.

Description

Technical Field

[0001] The present invention belongs to the field of third-generation nuclear power operation technology, and relates to a method for regulating the boron concentration of a nuclear waste liquid evaporator based on forced liquid level control. Specifically, it relates to a method for regulating the boron concentration of a radioactive waste liquid treatment system of a Hualong One nuclear power unit, and more particularly to a technical solution for achieving precise adjustment of the boron concentration of a concentrated liquid by regulating the dynamic operating parameters of the evaporator. Background Art

[0002] Depending on the composition of the wastewater, nuclear power plants use different treatment methods, such as filtration, desalination, and evaporation. Among them, evaporation is the final treatment method for nuclear power plant wastewater, used to treat wastewater with excessive radioactivity or specific ions.

[0003] During the evaporation process, the evaporator will produce a concentrated liquid. The evaporation will generally stop when the boron concentration reaches 38,000ppm to 44,000ppm, and the concentrated liquid will then be transferred to the solid waste storage tank for solidification treatment. Accurately adjusting the boron concentration in the evaporator to 38,000ppm to 44,000ppm is a key requirement of the solidification formula. At the same time, within this qualified range, the higher the boron concentration, the more significant the effect of saving solid waste space and funds. For example, taking the Hualong One evaporator as an example, adjusting the boron concentration from 38,000ppm to 42,000ppm can save about 0.8 cubic meters of solid waste space and about 100,000 yuan in solid waste funds. Therefore, accurately adjusting the boron concentration not only meets the needs of the solidification formula, but is also an important means to achieve cost reduction and efficiency improvement.

[0004] Despite the importance of precise regulation of boron concentration, practical applications currently face several bottlenecks. Due to the variable boron concentration of the treated raw liquid and the presence of a certain amount of feed during the heating process, it is difficult to adjust the boron concentration in the evaporator to the acceptable range of 38,000 ppm to 44,000 ppm in one go, especially when pursuing higher concentrations within this range to achieve cost savings. Therefore, precisely adjusting the boron concentration in the evaporator to a range of 38,000 ppm to 44,000 ppm, while maintaining a higher concentration within the acceptable range, remains a pressing technical challenge in nuclear power plant wastewater treatment. Summary of the Invention

[0005] This invention focuses on overcoming the existing technical challenges in controlling boron concentration in evaporators, namely the inability to accurately adjust boron concentration to the acceptable range of 38,000 ppm to 44,000 ppm, and the difficulty in achieving higher concentrations within this range to meet cost savings requirements. To this end, this invention proposes an efficient, stable, and economical method for regulating boron concentration in nuclear waste liquid evaporators based on forced liquid level control, precisely meeting the dual goals of precise boron concentration control and cost control during nuclear power plant waste liquid treatment.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for adjusting boron concentration in a nuclear waste liquid evaporator based on liquid level forced control comprises the following steps:

[0008] (1) Chemical sampling confirmed that the boron concentration in the evaporator was 38,000 ppm and that the boron concentration needed to be adjusted;

[0009] (2) Force the evaporator liquid level to 1600mm;

[0010] (3) The evaporator is started and operated to state 5, which indicates that the treated waste liquid is being converted into concentrated liquid;

[0011] (4) After the evaporator starts to state 5, the feed valve is immediately closed manually;

[0012] (5) Start timing when the distillate discharge flow meter has a reading;

[0013] (6) Shut down the evaporator;

[0014] (7) Chemical sampling evaporator boron concentration;

[0015] (8) If the sample does not reach the target boron concentration, repeat (3), (4), (5), (6), and (7);

[0016] (9) If the sampling reaches the target boron concentration, the forced signal is required to be restored;

[0017] (10) Arrange for the discharge of concentrated liquid.

[0018] (2) The maintenance instrumentation forces the evaporator liquid level to 1600 mm.

[0019] (6) Stop the evaporator after 10 minutes.

[0020] (9) If the sampling reaches the target boron concentration, the instrument control is required to restore the forced signal.

[0021] Applied to the evaporation treatment method of radioactive waste liquid in the Hualong One nuclear power plant.

[0022] The following steps are involved:

[0023] (1) Collect wastewater that is no longer reused during power plant operation and requires evaporation treatment and store it in chemical wastewater tanks;

[0024] (2) When the collected wastewater reaches a certain storage volume, the evaporator is started to separate the liquid from the impurities in the wastewater. The distillate produced by evaporation is stored in the distillate monitoring tank, and the concentrated liquid produced by evaporation is stored in the evaporator;

[0025] (3) The boron concentration of the concentrated liquid produced by evaporation is continuously increased during the startup of the evaporator. When the boron concentration reaches 42,000 to 44,000 ppm, the evaporator is stopped, the concentrated liquid in the evaporator is drained out, and then transported to the curing line for curing;

[0026] (4) After multiple evaporations, when the boron concentration of the concentrated liquid in the evaporator is between 38,000 and 42,000 ppm, it is necessary to further increase the boron concentration in the evaporator after evaluation;

[0027] (5) Force the evaporator liquid level to 1600mm;

[0028] (6) After the forced completion, start the evaporator to state 5, and then immediately manually close the feed valve;

[0029] (7) Start timing after seeing the distillate discharge valve open, and then stop the evaporator;

[0030] (8) After the evaporator is shut down, sample the concentrated liquid in the evaporator;

[0031] (9) Determine whether the evaporator needs to be restarted based on the sampling results. If necessary, repeat (5), (6), (7), and (8) until the boron concentration reaches the expected value;

[0032] (10) Restore the forced signal of the evaporator liquid level;

[0033] (11) The concentrated liquid is discharged and solidified.

[0034] (5) The instrumentation and control force the evaporator liquid level to 1600 mm.

[0035] (7) Start timing after seeing the distillate discharge valve open, count for 10 minutes, and then stop the evaporator.

[0036] (10) The instrumentation and control system provides a mandatory signal to restore the evaporator liquid level.

[0037] The beneficial effects achieved by the present invention are:

[0038] (1) Precise Control of Boron Concentration: This invention provides a method for precisely adjusting the boron concentration in the evaporator to the acceptable range of 38,000 ppm to 44,000 ppm, resolving the existing difficulty in achieving the desired boron concentration in a single step. Chemical sampling is used to confirm the boron concentration, and multiple adjustments are made based on the sampling results to ensure that the boron concentration reaches the desired value, meeting the key requirements of the curing formula.

[0039] (2) Raising boron concentration to a higher value: This invention not only adjusts boron concentration to the acceptable range but also achieves higher concentrations within that range, significantly saving both solid waste space and costs. For example, adjusting the boron concentration from 38,000 ppm to 42,000 ppm can save approximately 0.8 cubic meters of solid waste space and approximately 100,000 yuan in solid waste costs, achieving the goal of reducing costs and increasing efficiency.

[0040] (3) Efficient, stable, and economical: The method of the present invention achieves efficient, stable, and economical boron concentration adjustment by optimizing the evaporator's operating state and feed control strategy. Through forced liquid level control, manual closing of the feed valve, and timed operation, the evaporator ensures stable operation during boron concentration adjustment, reducing operational complexity and uncertainty.

[0041] (4) Strong adaptability: The method of the present invention is applicable to the radioactive waste liquid treatment system of the Hualong One nuclear power plant and can treat wastewater with different boron concentrations, ensuring precise control of boron concentration under different operating conditions. Through multiple evaporation and adjustment, it adapts to the changes in different wastewater compositions and treatment requirements.

[0042] (5) Simplified Operational Procedure: The method of the present invention simplifies the operation of adjusting the boron concentration through clear steps and operational procedures, reducing the workload of the operator and the risk of operational errors. The chemical sampling and timed operation steps ensure the simplicity and reliability of the operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Schematic diagram of the boron concentration adjustment method for nuclear waste liquid evaporator based on liquid level forced control DETAILED DESCRIPTION

[0044] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] A method for adjusting the boron concentration of an evaporator in a waste liquid treatment system comprises the following steps:

[0046] (1) Chemical sampling confirmed that the boron concentration in the evaporator was around 38,000 ppm and that the boron concentration needed to be adjusted.

[0047] (2) The maintenance instrumentation forces the evaporator liquid level to 1600 mm.

[0048] (3) Run the evaporator to state 5.

[0049] (4) After the evaporator starts to state 5, immediately close the feed valve manually.

[0050] (5) Start timing when the distillate discharge flow meter shows a reading.

[0051] (6) Stop the evaporator after 10 minutes.

[0052] (7) Chemical sampling evaporator boron concentration.

[0053] (8) If the sampling does not reach the target boron concentration, repeat (3), (4), (5), (6), and (7).

[0054] (9) If the sampling reaches the target boron concentration, the instrument control is required to restore the forced signal.

[0055] (10) Arrange for the discharge of concentrated liquid.

[0056] State 5: Indicates that the treated waste liquid is being converted into concentrated liquid.

[0057] The method for evaporating radioactive waste liquid from the Hualong One nuclear power plant preferably includes the following steps:

[0058] (1) Collect wastewater that is no longer reused during the operation of the power plant and needs to be evaporated and stored in chemical wastewater tanks.

[0059] (2) When the collected wastewater reaches a certain volume, the evaporator is started to separate the liquid from the impurities in the wastewater. The distillate produced by evaporation is stored in the distillate monitoring tank, and the concentrated liquid produced by evaporation is stored in the evaporator.

[0060] (3) The boron concentration of the concentrated liquid produced by evaporation is continuously increased during the startup of the evaporator. When the boron concentration reaches 42,000 to 44,000 ppm, the evaporator is stopped, the concentrated liquid in the evaporator is discharged, and then transported to the curing line for curing.

[0061] (4) After multiple evaporations, when the boron concentration of the concentrated liquid in the evaporator is between 38,000 and 42,000 ppm, it is necessary to further increase the boron concentration in the evaporator after evaluation.

[0062] (5) The instrumentation and control force the evaporator liquid level to 1600 mm.

[0063] (6) After the forced completion, start the evaporator to state 5, and then immediately manually close the feed valve.

[0064] (7) Start timing after seeing the distillate discharge valve open, count for 10 minutes, and then stop the evaporator.

[0065] (8) After the evaporator is shut down, take samples of the concentrated liquid in the evaporator.

[0066] (9) Determine whether the evaporator needs to be restarted based on the sampling results. If necessary, repeat (5), (6), (7), and (8) until the boron concentration reaches the expected value.

[0067] (10) The instrumentation and control system provides a mandatory signal to restore the evaporator liquid level.

[0068] (11) The concentrated liquid is discharged and solidified.

[0069] Example 1: The following is a case study of the present invention applied to the concentrate lifting of Fuqing Nuclear Power Unit 5.

[0070] After the overhaul of the Fuqing Nuclear Power Plant 602, the boron concentration of the first tank of Hualong One concentrated liquid reached 38198ppm, meeting the requirements for solid waste treatment. After solid waste suggestions and consultation with the operation, it was decided to adjust the boron concentration of the evaporator without feeding. The operation specialist, in coordination with the instrumentation and control, adopted the principle of small amounts and multiple times, and adjusted the boron concentration of the evaporator to 41294ppm, saving approximately 0.8m of solid waste space. 3 , saving about RMB 100,000 in solid waste disposal costs. The specific implementation steps are as follows:

[0071] (1) Develop a plan to increase the boron concentration of the concentrated liquid. Calculate the volume of liquid that needs to be evaporated by C0V0=C1(V1+V2), and establish relevant trends. Stop the evaporator before the distillate level reaches the target value to prevent the boron concentration from being too high and causing crystallization risks.

[0072] (2) Chemical sampling confirmed that the boron concentration in the evaporator was 38198 ppm. The boron concentration in the evaporator after 10 minutes was calculated and predicted according to the formula in (1).

[0073] (3) After the operation, instrumentation and solid waste professionals are in place, they are required to maintain the instrumentation and control to force the evaporator liquid level to 1600mm.

[0074] (4) Run the evaporator to state 5.

[0075] (5) After the evaporator starts to state 5, immediately close the feed valve manually.

[0076] (6) Start timing when the distillate discharge flow meter shows a reading.

[0077] (7) Stop the evaporator after 10 minutes.

[0078] (8) Chemical sampling evaporator boron concentration.

[0079] (9) Compare the predicted boron concentration value with the chemical sampling boron concentration value, and adjust the evaporation operation time according to the comparison, and then repeat (3), (4), (5), (6), and (7) until the boron concentration meets the expected value.

[0080] (10) When the sampling reaches the target boron concentration, the instrument control is required to restore the forced signal.

[0081] (11) Calculate the boron concentration in the evaporator based on the total volume of distillate evaporated during the concentration rise, and then arrange for the discharge of the concentrate.

Claims

1. A method for adjusting boron concentration in a nuclear waste liquid evaporator based on liquid level forced control, characterized in that: The following steps are involved: (1) Chemical sampling confirmed that the boron concentration in the evaporator was 38,000 ppm and that the boron concentration needed to be adjusted; (2) Force the evaporator liquid level to 1600mm; (3) The evaporator is started and operated to state 5, which indicates that the treated waste liquid is being converted into concentrated liquid; (4) After the evaporator starts to state 5, the feed valve is immediately closed manually; (5) Start timing when the distillate discharge flow meter has a reading; (6) Shut down the evaporator; (7) Chemical sampling evaporator boron concentration; (8) If the sample does not reach the target boron concentration, repeat (3), (4), (5), (6), and (7); (9) If the sampling reaches the target boron concentration, the forced signal is required to be restored; (10) Arrange for the discharge of concentrated liquid.

2. The method for adjusting boron concentration in a nuclear waste liquid evaporator based on liquid level forced control according to claim 1, characterized in that: (2) The maintenance instrumentation forces the evaporator liquid level to 1600 mm.

3. The method for adjusting boron concentration in a nuclear waste liquid evaporator based on liquid level forced control according to claim 1, characterized in that: (6) Stop the evaporator after 10 minutes.

4. The method for adjusting boron concentration in a nuclear waste liquid evaporator based on liquid level forced control according to claim 1, characterized in that: (9) If the sampling reaches the target boron concentration, the instrument control is required to restore the forced signal.

5. The method for adjusting boron concentration in a nuclear waste liquid evaporator based on liquid level forced control according to claim 1, characterized in that: Applied to the evaporation treatment method of radioactive waste liquid in the Hualong One nuclear power plant.

6. The method for adjusting boron concentration in a nuclear waste liquid evaporator based on liquid level forced control according to claim 5, characterized in that: The following steps are involved: (1) Collect wastewater that is no longer reused during power plant operation and requires evaporation treatment and store it in chemical wastewater tanks; (2) When the collected wastewater reaches a certain storage volume, the evaporator is started to separate the liquid from the impurities in the wastewater. The distillate produced by evaporation is stored in the distillate monitoring tank, and the concentrated liquid produced by evaporation is stored in the evaporator; (3) The boron concentration of the concentrated liquid produced by evaporation is continuously increased during the startup of the evaporator. When the boron concentration reaches 42,000 to 44,000 ppm, the evaporator is stopped, the concentrated liquid in the evaporator is drained out, and then transported to the curing line for curing; (4) After multiple evaporations, when the boron concentration of the concentrated liquid in the evaporator is between 38,000 and 42,000 ppm, it is necessary to further increase the boron concentration in the evaporator after evaluation; (5) Force the evaporator liquid level to 1600mm; (6) After the forced completion, start the evaporator to state 5, and then immediately manually close the feed valve; (7) Start timing after seeing the distillate discharge valve open, and then stop the evaporator; (8) After the evaporator is shut down, sample the concentrated liquid in the evaporator; (9) Determine whether the evaporator needs to be restarted based on the sampling results. If necessary, repeat (5), (6), (7), and (8) until the boron concentration reaches the expected value; (10) Restore the forced signal of the evaporator liquid level; (11) The concentrated liquid is discharged and solidified.

7. The method for adjusting boron concentration in a nuclear waste liquid evaporator based on liquid level forced control according to claim 6, characterized in that: (5) The instrumentation and control force the evaporator liquid level to 1600 mm.

8. The method for adjusting boron concentration in a nuclear waste liquid evaporator based on liquid level forced control according to claim 6, characterized in that: (7) Start timing after seeing the distillate discharge valve open, count for 10 minutes, and then stop the evaporator.

9. The method for adjusting boron concentration in a nuclear waste liquid evaporator based on liquid level forced control according to claim 6, characterized in that: (10) The instrumentation and control system provides a mandatory signal to restore the evaporator liquid level.

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