High-precision leakage monitoring system and method for heat supply systems such as pressurized water reactor

Abstract

The invention belongs to the technical field of nuclear power plant leakage monitoring, and particularly relates to a high-precision leakage monitoring system and method for a heat supply system of a unit such as a pressurized water reactor. Comprising external steam supply single-row or multi-row parallel heat supply pipelines with the same or different parameters, a demineralized water delivery pump, a preheater, a deaerator, an evaporator and a superheater which are sequentially connected with one another, and a demineralized water delivery pump rear sampling point is arranged between the demineralized water delivery pump and the preheater; a preheater rear sampling point is arranged between the preheater and the deaerator, a deaerator rear sampling point is arranged between the deaerator and the evaporator, an evaporator rear sampling point is arranged between the evaporator and the superheater, and a superheater rear sampling point is arranged behind the superheater. The method has the beneficial effects that trace leakage can be identified and measured in real time / in time, the working efficiency and timeliness of leakage detection are greatly improved, and economic, efficient and safe operation of a heat supply unit is further guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear power plant leakage monitoring, and in particular relates to a high-precision leakage monitoring system and method for a heating system of a pressurized water reactor or other unit. Background Art

[0002] Using nuclear energy to replace coal-fired cogeneration units for heating can achieve the goals of zero coal consumption and zero air pollution emissions, implement the national green and low-carbon energy development strategy, and effectively support the sustainable development of high-energy-consuming industries such as petrochemicals. At present, there are cases in China where pressurized water reactors and other units are used for civil heating and industrial heating. There are also many heating technology solutions for other reactor types such as high-temperature gas-cooled reactors, sodium-cooled fast reactors, and heavy water reactors. The pressurized water reactor + high-temperature gas-cooled reactor combined heating solution that a nuclear heating power plant plans to adopt has pushed the large-scale industrial application of nuclear energy to a new level. In order to ensure the safety and reliability of nuclear steam, nuclear heating processes mostly use simple wall heat exchange technology, using a series of heat exchangers such as preheaters, deaerators, evaporators, and superheaters to achieve heat transfer and isolate the working fluid.

[0003] If these heat exchange devices leak during operation, the steam temperature, pressure and flow rate will not meet the user's requirements, affecting the normal operation of the heating system and causing economic losses. In addition, the substances generated by the leakage will enter the user side along the heating circuit, which will bring some potential consequences.

[0004] Currently, the commonly used leakage monitoring methods such as flow meters and pressure gauges can only meet the monitoring requirements of larger flow leakage (the highest monitoring accuracy of common monitoring methods such as flow meters is only 1%). It is necessary to add high-precision leakage monitoring methods to detect trace leaks in time.

[0005] Therefore, there is an urgent need for a system and method for identifying and detecting trace leakage from the secondary heating circuit (secondary circuit) to the tertiary heating circuit (third circuit) under existing water quality conditions of units such as pressurized water reactors. Summary of the invention

[0006] The purpose of the present invention is to provide a high-precision leakage monitoring system and method for a pressurized water reactor and other heating systems, which can solve the problem of high-precision monitoring of leakage of secondary heating steam through a heat exchanger to a tertiary heating circuit.

[0007] The technical solution of the present invention is as follows: A high-precision leakage monitoring system for a heating system such as a pressurized water reactor comprises a single-row or multiple-row parallel heating pipeline for external steam supply with the same or different parameters, wherein the single-row heating pipeline is sequentially connected with a desalted water delivery pump, a preheater, a deaerator, an evaporator and a superheater, a sampling point after the desalted water delivery pump is provided between the desalted water delivery pump and the preheater, a sampling point after the preheater is provided between the preheater and the deaerator, a sampling point after the deaerator is provided between the deaerator and the evaporator, a sampling point after the evaporator is provided between the evaporator and the superheater, and a sampling point after the superheater is provided after the superheater.

[0008] The preheater, evaporator and superheater are one-stage or multi-stage, and the multi-stage preheater is arranged after the deaerator and before the evaporator.

[0009] The preheater is provided with a first steam pipeline, the second-circuit heating steam is introduced into the first steam pipeline, and a second-circuit heating steam sampling point is provided at the outlet of the first steam pipeline.

[0010] The deaerator introduces a small amount of deionized water heated by a deoxygenation evaporator with the same tritium activity as that at the sampling point behind the deionized water delivery pump for mixed heating.

[0011] The evaporator is provided with a third steam pipeline, the second-circuit heating steam is introduced into the third steam pipeline, and a second-circuit heating steam sampling point is provided at the outlet of the third steam pipeline.

[0012] The superheater is provided with a fourth steam pipeline, the second-circuit heating steam is introduced into the fourth steam pipeline, and a second-circuit heating steam sampling point is provided at the outlet of the fourth steam pipeline.

[0013] The outlet of the superheater is connected to a fifth pipeline, and a post-superheater sampling point is arranged on the fifth pipeline.

[0014] A high-precision leakage monitoring method for a heating system such as a pressurized water reactor comprises the following steps:

[0015] Step 1: Analyze the organic alkalizer concentration at the secondary circuit heating steam sampling point and the deaerator heating steam sampling point by online or offline ion chromatography to obtain the main steam organic alkalizer concentration C 二回路加热蒸汽 :C 11 , C 13 , C 15 and C 除氧器加热蒸汽 :C 17 ;

[0016] Step 2: Analyze the sampling points after the preheater, the evaporator, the superheater, and the deaerator by online or offline ion chromatography to obtain the organic alkalizer concentration C after the heat exchanger and the deaerator of each heating circuit. 换热器后:C4, C8, C10 and C 除氧器后 :C6;

[0017] Step 3: If only one heat exchanger in a single-row heating pipeline is leaking, that is, only one tritium activity value after the heating heat exchanger is greater than the inlet tritium activity value, according to C 换热器后 ×L 换热器后流量 =C 二回路加热蒸汽 ×L 二回路加热蒸汽泄漏流量 Since the leakage flow of the secondary heating steam is much smaller than the heat exchanger flow, the leakage rate Q = L 二回路加热泄漏流量 / L 换热器后流量 =C 换热器后 / C 二回路加热蒸汽 ×100%; if only a single heat exchanger in the heating circuit is leaking, enter the corresponding analysis data and calculate the leakage rate Q of each heat exchanger in each heating circuit in turn;

[0018] Step 4: If there are multiple heat exchangers leaking in a single heating pipeline, that is, the organic alkalizer concentration value after multiple heat exchangers is greater than the inlet organic alkalizer concentration value, the actual total tritium activity of the leaked heat exchanger of the latter heat exchanger needs to be subtracted from the total tritium activity of the previous heat exchanger;

[0019] 1) Leakage rate of superheater (9): (L 10 ×C 10 -L8×C8)=L 11 ×C 11 , L 10 =(L8+L 11 ), because L 11 The leakage flow rate is much smaller than that of L8. 10 ≈L8, so the leakage rate Q=L 11 / L 10 =(C 10 -C8) / C 11 ;

[0020] 2) Leakage rate of superheater (7): (L8×C8-L6×C6)=L 13 ×C 13 , L8=(L6+L 13 ), because L 13 The leakage flow rate of L8 is much smaller than that of L6, L8≈L6, so the leakage rate Q=L 13 / L8=(C8-C6) / C 13 ;

[0021] 3) The deaerator (5) is a mixed heating device, so there is no need to calculate the leakage amount;

[0022] 4) Preheater (3) is the first heat exchanger, and the calculation method is the same as step 3;

[0023] Step 5: Compare the leakage rate of the heat exchanger obtained with the allowable leakage rate, and decide whether to reduce the heating load or shut down the heat exchanger for maintenance based on the comparison result.

[0024] The beneficial effects of the present invention are as follows: the detection accuracy of the leakage monitoring system and method is significantly higher than that of commonly used leakage monitoring methods such as flow meters and pressure gauges. Since the second and third loop organic alkalizer online / offline detection modules are configured, trace leaks can be identified and measured in real time / promptly, which greatly improves the efficiency and timeliness of leakage detection work, thereby ensuring the economical, efficient and safe operation of the heating unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of a high-precision leakage monitoring system for a pressurized water reactor or other heating system provided by the present invention;

[0026] Figure 2 This is a flow chart of a high-precision leakage monitoring method for a heating system such as a pressurized water reactor provided by the present invention.

[0027] In the figure: 1 desalted water delivery pump, 2 sampling point after desalted water delivery pump, 3 preheater, 4 sampling point after preheater, 5 deaerator, 6 sampling point after deaerator, 7 evaporator, 8 sampling point after evaporator, 9 superheater, 10 sampling point after superheater, 11 sampling point of superheater secondary circuit heating steam inlet, 12 sampling point of superheater secondary circuit heating steam outlet, 13 sampling point of evaporator secondary circuit heating steam inlet, 14 sampling point of evaporator secondary circuit heating steam outlet, 15 sampling point of preheater secondary circuit heating steam inlet, 16 sampling point of preheater secondary circuit heating steam outlet, 17 sampling point of deaerator heating steam outlet. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] The chemical additives in the condensate-feed water-steam loop (secondary loop) of pressurized water reactors and other units are generally mainly ammonia and hydrazine. The chemical additives in the tertiary side heating loop (tertiary loop) are generally mainly ammonia and hydrazine. The chemical reagents added in both are the same and the concentrations are similar. It is impossible to judge trace leaks by detecting changes in the concentrations of these commonly used chemical reagents.

[0030] The full volatilization treatment using ammonia and hydrazine is a commonly used water chemical treatment method for the secondary loop system of a pressurized water reactor nuclear power plant. However, due to the large volatility coefficient of ammonia, the ammonia content in the water phase in the steam-water two-phase region will be significantly less, the pH will be low, and the flow accelerated corrosion rate of materials such as carbon steel and low-alloy steel will be large. At present, newly built pressurized water reactors and other units usually use organic alkalizers such as ethanolamine and morpholine as auxiliary agents, and control the concentration value range of several to tens of mg / L to adjust the concentration of the steam-water two-phase alkalizer to inhibit material corrosion. Taking ethanolamine as an example, the steam-water partition coefficients at 150°C and 300°C are 0.26 and 0.66 respectively, so the use of ethanolamine can make up for the lack of ammonia.

[0031] At present, the lower limit of organic alkalizers measured by offline or online organic alkalizer monitoring equipment (ion chromatograph) is below 1-10ug / kg. Therefore, the trace leakage of main steam to the heating circuit can be monitored by detecting the organic amine concentration after the heat exchanger. The monitored leakage rate (in terms of flow meter, the ratio of the flow rate of the secondary circuit leaking into the heating circuit to the flow rate of the heating circuit) can reach an accuracy of about 0.05%-0.5%.

[0032] If only one heat exchanger in a single-row heating pipeline leaks, that is, only one tritium activity value after the heating heat exchanger is greater than the inlet tritium activity value:

[0033] C 换热器后 ×L 换热器后流量 =C 二回路加热蒸汽 ×L 二回路加热蒸汽泄漏流量 (1)

[0034] The leakage rate is defined as:

[0035] Q=L 二回路加热蒸汽泄漏流量 / L 换热器后流量 ×100% (2)

[0036] Therefore, the leakage rate calculation formula is as follows:

[0037] Q=C 换热器后 / C 二回路加热蒸汽 ×100% (3)

[0038] If there are multiple heat exchangers leaking in a single heating pipeline, that is, the tritium activity value after multiple heat exchangers is greater than the inlet tritium activity value, take superheater 9 as an example:

[0039] 1) Leakage rate of superheater (9): (L 10 ×C 10 -L8×C8)=L 11 ×C 11 , L 10 =(L8+L 11 ), because L 11 The leakage flow rate is much smaller than that of L8. 10≈L8, so the leakage rate Q=L 11 / L 10 =(C 10 -C8) / C 11 ;

[0040] 2) Leakage rate of superheater (7): (L8×C8-L6×C6)=L 13 ×C 13 , L8=(L6+L 13 ), because L 13 The leakage flow rate of L8 is much smaller than that of L6, L8≈L6, so the leakage rate Q=L 13 / L8=(C8-C6) / C 13 ;

[0041] 3) The deaerator (5) is a mixed heating device and does not need to calculate the leakage.

[0042] 4) Preheater (3) is the first heat exchanger, and the calculation method is the same as step 3.

[0043] like Figure 1 As shown, a high-precision leakage monitoring system for a heating system such as a pressurized water reactor comprises a preheater 1, a deaerator 3, an evaporator 5 and a superheater 7, wherein the preheater 1 is connected to the deaerator 3 through a pipeline, the deaerator 3 is connected to the evaporator 5 through a pipeline, the evaporator 5 is connected to the superheater 7 through a pipeline, the preheater 1, the deaerator 3, the evaporator 5 and the superheater 7 are all provided with a secondary circuit heating steam 9 and a secondary circuit heating steam sampling point 10, a preheater post-sampling point 2 is provided on the pipeline between the preheater 1 and the deaerator 3, a deaerator post-sampling point 4 is provided on the pipeline between the deaerator 3 and the evaporator 5, an evaporator post-sampling point 4 is provided on the pipeline between the evaporator 5 and the superheater 7, a superheater post-sampling point 8 is provided on the pipeline at the rear end of the superheater 7, and a superheater post-sampling point 10 is provided after the superheater.

[0044] A high-precision leakage monitoring method for a heating system such as a pressurized water reactor comprises the following steps:

[0045] Step 1: Analyze the organic alkalizer concentrations at the secondary circuit heating steam sampling points (11), (13), (15) and the deaerator heating steam sampling point (17) by online or offline ion chromatography to obtain the main steam organic alkalizer concentration C 二回路加热蒸汽 :C 11 , C 13 , C 15 and C 除氧器加热蒸汽 :C 17 ;

[0046] Step 2: Analyze the sampling point (4) after the preheater, the sampling point (8) after the evaporator, the sampling point (10) after the superheater, and the sampling point (6) after the deaerator by online or offline ion chromatography to obtain the organic alkalizing agent concentration C after the heat exchanger and the deaerator of each heating circuit. 换热器后 :C4, C8, C10 and C 除氧器后 :C6;

[0047] Step 3: If only one heat exchanger in a single-row heating pipeline is leaking, that is, only one tritium activity value after the heating heat exchanger is greater than the inlet tritium activity value, according to C 换热器后 ×L 换热器后流量 =C 二回路加热蒸汽 ×L 二回路加热蒸汽泄漏流量 Since the leakage flow of the secondary heating steam is much smaller than the heat exchanger flow, the leakage rate Q = L 二回路加热泄漏流量 / L 换热器后流量 =C 换热器后 / C 二回路加热蒸汽 × 100%. If only a single heat exchanger in the heating circuit is leaking, enter the corresponding analysis data and calculate the leakage rate Q of each heat exchanger (3), (7), and (9) in each heating circuit in turn;

[0048] Where: Q: leakage rate, %; C 换热器后 : The measured value of organic alkalizer after the heat exchanger of the heating circuit, ug / kg; C2: The measured value of organic alkalizer of the heating steam of the secondary circuit, ug / kg; L 换热器后流量 : Flow rate after the heat exchanger of the heating circuit, kg / s; L 二回路加热泄漏流量 : Secondary circuit heating steam leakage flow, kg / s.

[0049] Step 4: If there are multiple leaking heat exchangers in a single heating pipeline, that is, the organic alkalizer concentration value after multiple heating exchangers is greater than the inlet organic alkalizer concentration value, the actual total tritium activity of the leaked heat exchanger of the latter heating exchanger needs to be subtracted from the total tritium activity of the previous heat exchanger.

[0050] 1) Leakage rate of superheater (9): (L 10 ×C 10 -L8×C8)=L 11 ×C 11 , L 10 =(L8+L 11 ), because L 11 The leakage flow rate is much smaller than that of L8. 10 ≈L8, so the leakage rate Q=L 11 / L 10 =(C 10 -C8) / C 11 ;

[0051] 2) Leakage rate of superheater (7): (L8×C8-L6×C6)=L 13 ×C 13 , L8=(L6+L 13 ), because L 13 The leakage flow rate of L8 is much smaller than that of L6, L8≈L6, so the leakage rate Q=L 13 / L8=(C8-C6) / C 13 ;

[0052] 3) The deaerator (5) is a mixed heating device and does not need to calculate the leakage.

[0053] 4) Preheater (3) is the first heat exchanger, and the calculation method is the same as step 3.

[0054] Step 5: Compare the leakage rate of the heat exchanger obtained with the allowable leakage rate, and take corresponding actions such as reducing the heating load or shutting down for maintenance based on the comparison results.

[0055] All changes and modifications to the control strategy of the present invention should fall within the scope of the present invention.

Claims

1. A high-precision leakage monitoring system for pressurized water reactor and other heating systems, characterized by: It comprises a single-row or multiple-row parallel heating pipeline for external steam supply with the same or different parameters, wherein the single-row heating pipeline is sequentially connected with a desalted water delivery pump, a preheater, a deaerator, an evaporator and a superheater, a sampling point after the desalted water delivery pump is provided between the desalted water delivery pump and the preheater, a sampling point after the preheater is provided between the preheater and the deaerator, a sampling point after the deaerator is provided between the deaerator and the evaporator, a sampling point after the evaporator is provided between the evaporator and the superheater, and a sampling point after the superheater is provided after the superheater.

2. The system for high-precision leakage monitoring of heating systems of high-temperature gas-cooled reactors and the like as claimed in claim 1, characterized in that: The preheater, evaporator and superheater are one-stage or multi-stage, and the multi-stage preheater is arranged after the deaerator and before the evaporator.

3. The system for high-precision leakage monitoring of heating systems of high-temperature gas-cooled reactors and the like as claimed in claim 1, characterized in that: The preheater is provided with a first steam pipeline, the second-circuit heating steam is introduced into the first steam pipeline, and a second-circuit heating steam sampling point is provided at the outlet of the first steam pipeline.

4. The system for high-precision leakage monitoring of a heating system of a high-temperature gas-cooled reactor or the like as claimed in claim 1, characterized in that: The deaerator introduces a small amount of deionized water heated by a deoxygenation evaporator with the same tritium activity as that at the sampling point behind the deionized water delivery pump for mixed heating.

5. The system for high-precision leakage monitoring of heating systems of high-temperature gas-cooled reactors and the like as claimed in claim 1, characterized in that: The evaporator is provided with a third steam pipeline, the second-circuit heating steam is introduced into the third steam pipeline, and a second-circuit heating steam sampling point is provided at the outlet of the third steam pipeline.

6. The system for high-precision leakage monitoring of heating systems of high-temperature gas-cooled reactors and the like as claimed in claim 1, characterized in that: The superheater is provided with a fourth steam pipeline, the second-circuit heating steam is introduced into the fourth steam pipeline, and a second-circuit heating steam sampling point is provided at the outlet of the fourth steam pipeline.

7. The system for high-precision leakage monitoring of a heating system of a high-temperature gas-cooled reactor or the like as claimed in claim 1, characterized in that: The outlet of the superheater is connected to a fifth pipeline, and a post-superheater sampling point is arranged on the fifth pipeline.

8. A high-precision leakage monitoring method for a heating system such as a pressurized water reactor, characterized in that: The steps include: Step 1: Analyze the organic alkalizer concentration at the secondary circuit heating steam sampling point and the deaerator heating steam sampling point by online or offline ion chromatography to obtain the main steam organic alkalizer concentration C 二回路加热蒸汽 :C 11 , C 13 , C 15 and C 除氧器加热蒸汽 :C 17 ; Step 2: Analyze the sampling points after the preheater, the evaporator, the superheater, and the deaerator by online or offline ion chromatography to obtain the organic alkalizer concentration C after the heat exchanger and the deaerator of each heating circuit. 换热器后 :C4, C8, C10 and C 除氧器后 :C6; Step 3: If only one heat exchanger in a single-row heating pipeline is leaking, that is, only one tritium activity value after the heating heat exchanger is greater than the inlet tritium activity value, according to C 换热器后 ×L 换热器后流量 =C 二回路加热蒸汽 ×L 二回路加热蒸汽泄漏流量 Since the leakage flow of the secondary heating steam is much smaller than the heat exchanger flow, the leakage rate Q = L 二回路加热泄漏流量 / L 换热器后流量 =C 换热器后 / C 二回路加热蒸汽 ×100%; if only a single heat exchanger in the heating circuit is leaking, enter the corresponding analysis data and calculate the leakage rate Q of each heat exchanger in each heating circuit in turn; Step 4: If there are multiple heat exchangers leaking in a single heating pipeline, that is, the organic alkalizer concentration value after multiple heat exchangers is greater than the inlet organic alkalizer concentration value, the actual total tritium activity of the leaked heat exchanger of the latter heat exchanger needs to be subtracted from the total tritium activity of the previous heat exchanger; 1) Leakage rate of superheater (9): (L 10 ×C 10 -L8×C8)=L 11 ×C 11 , L 10 =(L8+L 11 ), because L 11 The leakage flow rate is much smaller than that of L8. 10 ≈L8, so the leakage rate Q=L 11 / L 10 =(C 10 -C8) / C 11 ; 2) Leakage rate of superheater (7): (L8×C8-L6×C6)=L 13 ×C 13 , L8=(L6+L 13 ), because L 13 The leakage flow rate of L8 is much smaller than that of L6, L8≈L6, so the leakage rate Q=L 13 / L8=(C8-C6) / C 13 ; 3) The deaerator (5) is a mixed heating device, so there is no need to calculate the leakage amount; 4) Preheater (3) is the first heat exchanger, and the calculation method is the same as step 3; Step 5: Compare the leakage rate of the heat exchanger obtained with the allowable leakage rate, and decide whether to reduce the heating load or shut down the heat exchanger for maintenance based on the comparison result.

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