Device for reducing failure rate of blow-down electric valve of steam generator

Abstract

The invention belongs to the technical field of nuclear power station operation and automatic control, and particularly relates to a device for reducing the failure rate of a steam generator blow-down electric valve. Comprising a steam generator, a steam generator bottom periodic blowdown pipeline is arranged in the middle of the bottom of the steam generator, a valve is installed on the steam generator bottom periodic blowdown pipeline, and the two sides of the bottom of the steam generator are connected with a steam generator hot end periodic blowdown pipeline and a steam generator cold end periodic blowdown pipeline respectively. The invention has the following beneficial effects: 1) the regular blowdown pipeline regulating valve is arranged, so that when the flow of the corresponding pipeline needs to be reduced, the flow of the pipeline can be controlled without closing the electric stop valve, and the fault probability of the valve is reduced; meanwhile, the probability of entering a reactor building to overhaul the valve during power operation is also reduced, and the burden of operation and maintenance personnel is reduced; and 2) the regular blowdown pipeline is additionally arranged at the cold end of the steam generator, so that the regular blowdown flow is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear power plant operation and automatic control, and in particular relates to a device for reducing the failure rate of a steam generator blowdown electric valve. Background Art

[0002] There are many types of modern nuclear power plants, among which pressurized water reactor power plants are the main representatives of the third generation of nuclear power plants. Different from traditional thermal power plants, the energy extraction method of pressurized water reactor nuclear power plants is to release a large amount of heat by controlling the nuclear fuel to undergo a controllable chain fission reaction. The primary coolant takes the heat released by the nuclear fuel out of the reactor and sends the heat to the steam generator. The steam generator then transfers the heat to the feed water on the secondary side through the heat transfer tube, causing the secondary feed water to boil and produce steam. At the same time, the primary coolant with a reduced temperature returns to the reactor, and the coolant heated by the reactor is sent to the steam generator again. This reciprocating cycle forms a closed loop, which continuously extracts the core energy.

[0003] Feed water is transported by the feed water pump into the secondary side of the steam generator. The first-loop coolant from the reactor core outlet enters the primary side of the steam generator and transfers heat to the feed water through the steam generator heat transfer tube. After receiving the heat, the feed water in the steam generator rises in temperature and is heated to saturation. Steam is generated after the feed water in the steam generator is saturated. The steam passes through the underwater steam plate and the upper steam orifice plate in the steam generator to separate part of the water. In the process of steam rising to the steam main pipe, part of the water will also be separated due to its own gravity. After the above process, the steam generator generates steam that meets the humidity requirements of the steam turbine. As a heat exchanger, the steam generator will inevitably accumulate impurities during operation. The main reasons for the generation of impurities are as follows: during the process of converting feed water into steam in the steam generator, the feed water changes from liquid to gas, and some non-vaporized compounds in the feed water will remain in the liquid; due to the structural characteristics and thermal-hydraulic characteristics of the steam generator, secondary side stagnation areas and structural gap areas will be formed, and the boiling process will cause high-concentration impurities to be produced locally in the steam generator; relative to the steam and feed water flow, the flow of the steam generator sewage system is very small, and impurities are easily deposited and concentrated after entering the steam generator.

[0004] The function of the steam generator sewage system is to collect the sewage from the steam generator, introduce the sewage from the steam generator into the purification system for purification, and transport the purified water to the deaerator, so as to maintain the chemical condition of the secondary circuit water. For example, the steam generator used in a certain domestic nuclear power plant unit is a horizontal steam generator. The steam generator is large in size, the number of sewage pipelines is large, the sewage flow control is relatively complex, and the sewage effect is greatly affected by the sewage flow. Among them, the collecting pipe cavity chamber of the steam generator and the bottom of the steam generator are prone to accumulate impurities during the steam generator sewage process. Therefore, the steam generator sewage system is designed with a special regular sewage pipeline to discharge the part where impurities are easily accumulated to reduce aggregation and accumulation.

[0005] The periodic sewage system is equipped with drainage interfaces at the bottom of the steam generator and the concentrated distribution part of the heat transfer tubes of the steam generator, which can discharge water with high impurity concentration from the steam generator. In order to reasonably distribute the sewage flow to ensure the sewage discharge effect, a sewage discharge program is set up and the sewage discharge flow is controlled by controlling the electric stop valve and regulating valve on the periodic sewage discharge pipeline. The stop valve is arranged in the reactor building and the regulating valve is arranged outside the reactor building. The sewage discharge program controls the sewage discharge sequence by switching the stop valve on the sewage discharge pipeline, and the sewage discharge flow is controlled by the opening of the regulating valve on the sewage discharge pipeline. During the long-term operation of the unit, the stop valve on the sewage discharge pipeline is switched on and off for a long time. Due to the high working environment temperature of the valve and the high environmental radiation dose, the electric valve on the periodic sewage discharge pipeline often fails and cannot be switched reliably. Although the flow can be controlled by the regulating valve, the total sewage discharge flow is unevenly distributed due to the inability to control the sewage discharge position, resulting in a decrease in sewage discharge effect.

[0006] Therefore, it is necessary to invent a steam generator boiler water blowdown electric valve action control device, through which the blowdown flow distribution is optimized to ensure the blowdown effect of the steam generator. Summary of the invention

[0007] The purpose of the present invention is to provide a device for reducing the failure rate of the steam generator sewage electric valve, by reducing the frequency of valve switching on and off on the regular sewage pipeline during operation, reducing and avoiding the possibility of valve failure, while improving the regular sewage discharge effect of the steam generator, ensuring reliable sewage discharge of the steam generator under long-term operation, reducing the accumulation of impurities in the steam generator, increasing the service life of the steam generator, and ensuring safe and stable operation of the unit.

[0008] The technical scheme of the present invention is as follows: a device for reducing the failure rate of a steam generator sewage electric valve, comprising a steam generator, a steam generator bottom periodic sewage pipeline is arranged in the middle of the bottom of the steam generator, a valve is installed on the steam generator bottom periodic sewage pipeline, the two sides of the bottom of the steam generator are respectively connected to the steam generator hot end periodic sewage pipeline and the steam generator cold end periodic sewage pipeline, the steam generator hot end periodic sewage pipeline is installed with a first valve on the steam generator periodic sewage pipeline, and the steam generator cold end periodic sewage pipeline is installed with a first valve on the steam generator periodic sewage pipeline. The sixth valve on the steam generator periodic sewage pipeline, the steam generator bottom periodic sewage pipeline is also connected to the steam generator bottom periodic sewage pipeline regulating valve, the steam generator bottom periodic sewage pipeline, the steam generator hot end periodic sewage pipeline and the steam generator cold end periodic sewage pipeline are converged and connected to the sewage expansion tank through the steam generator periodic sewage pipeline regulating valve, the cold end of the steam generator is connected to the steam generator continuous sewage pipeline, the steam generator continuous sewage pipeline is installed with a steam generator continuous sewage pipeline regulating valve, and the steam generator continuous sewage pipeline is connected to the sewage expansion tank.

[0009] The regular sewage discharge pipeline at the bottom of the steam generator includes 4 pipelines, each of which is connected to the bottom of the steam generator, and each pipeline is installed with a valve.

[0010] The four pipelines include a first pipeline, a second pipeline, a third pipeline and a fourth pipeline.

[0011] The first pipeline is provided with a second valve on the steam generator periodic sewage discharge pipeline.

[0012] The second pipeline is equipped with a third valve on the steam generator periodic sewage discharge pipeline.

[0013] The third pipeline is equipped with a fourth valve on the steam generator periodic sewage discharge pipeline.

[0014] The fourth pipeline is equipped with a fifth valve on the steam generator periodic sewage discharge pipeline.

[0015] The beneficial effects of the present invention are:

[0016] 1) The present invention is equipped with a regular sewage pipeline regulating valve. When the corresponding pipeline flow needs to be reduced, the pipeline flow control can be achieved without closing the electric stop valve, reducing the probability of valve failure. At the same time, it also reduces the probability of entering the reactor building to inspect the valve during power operation, reducing the burden on operation and maintenance personnel;

[0017] 2) A regular sewage discharge pipeline is added at the cold end of the steam generator, which increases the regular sewage discharge flow rate, so that the impurities accumulated and concentrated in the steam generator can be discharged quickly, thereby improving the sewage discharge efficiency of the steam generator;

[0018] 3) The present invention optimizes the number of sewage pipelines at the steam generator header and header ring positions, making the sewage flow distribution more scientific and improving the sewage discharge efficiency of the steam generator;

[0019] 4) By increasing the diameter of the regular sewage pipeline, the sewage flow rate is increased, so that the overall sewage flow rate of the steam generator is increased, and the impurities concentrated and accumulated in the steam generator are discharged more effectively;

[0020] 5) The present invention provides a set of steam generator blowdown flow control logic according to the layout and structural characteristics of the steam generator blowdown pipeline, thereby maximizing the blowdown effect of the steam generator within the flow range of the system design. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of a device for reducing the failure rate of a steam generator sewage electric valve provided by the present invention.

[0022] In the figure: 1 steam generator, 2 regular sewage discharge pipeline at the bottom of the steam generator, 3 regular sewage discharge pipeline at the hot end of the steam generator, 4 regular sewage discharge pipeline at the cold end of the steam generator, 5 continuous sewage discharge pipeline of the steam generator, 6 sewage expansion tank, 7 regulating valve of the continuous sewage discharge pipeline of the steam generator, 8 regulating valve of the regular sewage discharge pipeline at the bottom of the steam generator, 9 regulating valve of the regular sewage discharge pipeline of the steam generator, 11 the first valve on the regular sewage discharge pipeline of the steam generator, 12 the second valve on the regular sewage discharge pipeline of the steam generator, 13 the third valve on the regular sewage discharge pipeline of the steam generator, 14 the fourth valve on the regular sewage discharge pipeline of the steam generator, 15 the fifth valve on the regular sewage discharge pipeline of the steam generator, 16 the sixth valve on the regular sewage discharge pipeline of the steam generator. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] The technical problem to be solved by the present invention is: in view of the problem that the frequent operation of the electric valve on the steam generator sewage pipeline during normal operation leads to an increased probability of valve failure, a device for reducing the failure rate of the steam generator sewage electric valve is provided, which can reduce the number of valve operations on the sewage pipeline, improve the sewage discharge effect, and reduce or avoid valve failure.

[0025] The main problems solved by the present invention are as follows:

[0026] 1) Reduce the number of times the electric valve of the steam generator sewage pipeline is opened and closed;

[0027] 2) Optimize the blowdown position of the steam generator to improve the blowdown effect;

[0028] 3) Allocate the flow of the sewage pipeline to improve the sewage discharge effect of the steam generator;

[0029] To solve the above technical problems, the solutions adopted are as follows:

[0030] 1) Add a branch regulating valve to the regular sewage pipeline to reduce the number of times the sewage valve of the regular sewage pipeline is opened and closed by adjusting the flow of the corresponding regular sewage pipeline;

[0031] 2) Add a steam generator blowdown pipeline at the cold end of the steam generator to increase the blowdown flow rate;

[0032] 3) Optimize the layout of the steam generator header and header ring sewage pipelines and adjust the sewage flow rate;

[0033] 4) Regularly drain the sewage pipeline at the bottom of the steam generator to increase the sewage flow rate;

[0034] 5) Optimize the steam generator blowdown control strategy based on the number of blowdown pipelines and pipeline distribution characteristics.

[0035] like Figure 1 As shown, a device for reducing the failure rate of a steam generator blowdown electric valve comprises a steam generator 1, a steam generator bottom periodic blowdown pipeline 2 is arranged at the middle position of the bottom of the steam generator 1, and a valve is installed on the steam generator bottom periodic blowdown pipeline 2. Specifically, the steam generator bottom periodic blowdown pipeline 2 comprises 4 pipelines (a first pipeline, a second pipeline, a third pipeline and a fourth pipeline), each of which is connected to the bottom of the steam generator 1, wherein each pipeline is installed with a valve. Specifically, a second valve 12 on a steam generator periodic sewage pipeline is installed on the first pipeline, a third valve 13 on a steam generator periodic sewage pipeline is installed on the second pipeline, a fourth valve 14 on a steam generator periodic sewage pipeline is installed on the third pipeline, and a fifth valve 15 on a steam generator periodic sewage pipeline is installed on the fourth pipeline. The two sides of the bottom of the steam generator 1 are respectively connected to a steam generator hot end periodic sewage pipeline 3 and a steam generator cold end periodic sewage pipeline 4. The first valve 11 on the steam generator periodic sewage pipeline is installed on the steam generator hot end periodic sewage pipeline 3, and the first valve 12 on the steam generator periodic sewage pipeline is installed on the steam generator cold end periodic sewage pipeline 4. A sixth valve 16 is installed on the steam generator periodic sewage pipeline, and the steam generator bottom periodic sewage pipeline 2 is also connected to the steam generator bottom periodic sewage pipeline regulating valve 8. The steam generator bottom periodic sewage pipeline 2, the steam generator hot end periodic sewage pipeline 3 and the steam generator cold end periodic sewage pipeline 4 are converged and connected to the sewage expansion tank 6 through the steam generator periodic sewage pipeline regulating valve 9. The cold end of the steam generator 1 is connected to the steam generator continuous sewage pipeline 5, and the steam generator continuous sewage pipeline 5 is installed with a steam generator continuous sewage pipeline regulating valve 7. The steam generator continuous sewage pipeline 5 is connected to the sewage expansion tank 6.

[0036] Embodiment 1:

[0037] like Figure 1 As shown, the steam generator is in continuous blowdown condition. Under normal operation of the unit, the four steam generators are blown down in sequence. For the three steam generators that are not in periodic blowdown, the blowdown is carried out as follows.

[0038] Continuous sewage discharge is carried out from the continuous sewage discharge line 5 of the salt chamber part of the cold end of the steam generator at a flow rate of 4.2 kg / s, and the sewage discharge flow rate is controlled by the regulating valve 7 on the continuous sewage discharge line; regular sewage discharge is carried out from the periodic sewage discharge lines 3 and 4 of the steam generator shell at a flow rate of 1.4 kg / s, and the sewage discharge flow rate is controlled by the steam generator periodic sewage discharge line regulating valve 9 to keep the pipeline preheated; regular sewage discharge is carried out from the sewage discharge line 2 at the bottom of the steam generator shell at a flow rate of 1.4 kg / s, and the sewage discharge flow rate is controlled by the sewage discharge line regulating valve 8 at the bottom of the steam generator shell to keep the pipeline preheated.

[0039] Embodiment 2:

[0040] like Figure 1 As shown in the figure, the steam generator is in the periodic blowdown condition. Under the periodic blowdown condition, the operator starts the steam generator blowdown control program. The periodic blowdown of the four steam generators is carried out in sequence according to the periodic blowdown of each steam generator.

[0041] Basic mode: In this mode, a steam generator is discharged as follows for 60 minutes: continuous sewage discharge is carried out from the continuous sewage line 5 of the salt chamber part of the cold end of the steam generator at a flow rate of 6.9 kg / s, and the sewage flow rate is controlled by the regulating valve 7 on the continuous sewage line, and maintained for 60 minutes; regular sewage discharge is carried out from the sewage line 2 at the bottom of the steam generator shell at a flow rate of 11.1 kg / s, and regular sewage discharge is carried out from the regular sewage lines 3 and 4 of the steam generator shell at a flow rate of 11.1 kg / s, and the sewage flow rate is controlled by the sewage line regulating valve 8 at the bottom of the steam generator shell for 30 minutes; regular sewage discharge is carried out from the sewage line 2 at the bottom of the steam generator shell at a flow rate of 0 kg / s, and regular sewage discharge is carried out from the regular sewage lines 3 and 4 of the steam generator shell at a flow rate of 9.7 kg / s, and the sewage flow rate is controlled by the regular sewage line regulating valve 9 of the steam generator for 30 minutes.

[0042] Then the next steam generator is periodically drained. The basic mode mainly uses the regulating valve for drainage to reduce the number of switching actions of the isolation valve, and regularly cleans the steam generator shell bottom drainage pipeline 2 and the steam generator shell periodic drainage pipelines 3 and 4 to remove as many impurities as possible from the steam generator surface.

[0043] Embodiment 3:

[0044] Enhanced mode: In this mode, a steam generator is discharged as follows for 120 minutes. Take a steam generator as an example: continuous sewage discharge is carried out from the continuous sewage discharge line 5 of the salt chamber part of the cold end of the steam generator at a flow rate of 4.2 kg / s. The sewage discharge flow rate is controlled by the regulating valve 7 on the continuous sewage discharge line and maintained for 120 minutes; regular sewage discharge is carried out from the sewage discharge line 2 at the bottom of the steam generator shell at a flow rate of 2.8 kg / s, and regular sewage discharge is carried out from the regular sewage discharge lines 3 and 4 of the steam generator shell at a flow rate of 11.1 kg / s. The sewage discharge flow rate is controlled by the regulating valve 8 at the bottom of the steam generator shell and the regulating valve 9 of the regular sewage discharge line of the steam generator, and maintained for 120 minutes; the sewage discharge line 2 at the bottom of the steam generator shell is controlled by the regulating valve 8 at the bottom of the steam generator shell and the regulating valve 9 at the bottom of the steam generator shell. The regulating valve 8 maintains a flow rate of 11.1 kg / s, and the regular sewage pipelines 3 and 4 of the steam generator shell are each discharged for 60 minutes; - For the steam generator shell bottom sewage pipeline 2, the steam generator shell bottom sewage pipeline regulating valve 8 and the steam generator regular sewage pipeline regulating valve 9 are used to control and maintain a flow rate of 2.8 kg / s, and each of the regular sewage valves on the steam generator shell bottom sewage pipeline 2 is opened for 30 minutes for sewage discharge; After the regular sewage discharge of all pipelines is completed, the program gives the steam generator shell bottom sewage pipeline regulating valve 8 to maintain a flow rate of 1.4 kg / s, the steam generator regular sewage pipeline regulating valve 9 to maintain a flow rate of 2.8 kg / s, and opens the valves on the steam generator regular sewage pipeline to ensure that the regular sewage pipeline is in a preheating condition.

[0045] Embodiment 4:

[0046] Continuous blowdown of steam generators in case of deterioration of water chemistry in the secondary circuit When the water chemistry in the secondary circuit deteriorates, continuous blowdown of steam generators is carried out on all four steam generators at the same time, and the following blowdowns are carried out from each steam generator: Continuous blowdown line 5 of the cold end salt chamber of the steam generator is continuously discharged at a flow rate of 6.9 kg / s, which is controlled by the regulating valve 7 on the continuous blowdown line; Periodic blowdown is carried out from the blowdown line 2 at the bottom of the steam generator shell at a flow rate of 1.4 kg / s, and the blowdown flow rate is controlled by the regulating valve 8 of the blowdown line at the bottom of the steam generator shell; Periodic blowdown is carried out from the periodic blowdown lines 3 and 4 of the steam generator shell at a flow rate of 1.4 kg / s, and the blowdown flow rate is controlled by the regulating valve 9 of the periodic blowdown line of the steam generator. Until the water quality of the steam generator is restored, the blowdown mode is switched to the basic mode.

[0047] Basic Mode:

[0048]

[0049]

[0050] Enhanced Mode

[0051]

[0052] It is to be understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present invention, but the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered as the protection scope of the present invention.

Claims

1. A device for reducing the failure rate of a steam generator blowdown electric valve, characterized in that: The invention comprises a steam generator, wherein a regular sewage discharge pipeline of the bottom of the steam generator is arranged in the middle position of the bottom of the steam generator, a valve is installed on the regular sewage discharge pipeline of the bottom of the steam generator, the two sides of the bottom of the steam generator are respectively connected with the regular sewage discharge pipeline of the hot end of the steam generator and the regular sewage discharge pipeline of the cold end of the steam generator, the first valve of the regular sewage discharge pipeline of the steam generator is installed on the regular sewage discharge pipeline of the hot end of the steam generator, the sixth valve of the regular sewage discharge pipeline of the steam generator is installed on the regular sewage discharge pipeline of the cold end of the steam generator, the regular sewage discharge pipeline of the bottom of the steam generator is also connected with the regular sewage discharge pipeline regulating valve of the bottom of the steam generator, the regular sewage discharge pipeline of the bottom of the steam generator, the regular sewage discharge pipeline of the hot end of the steam generator and the regular sewage discharge pipeline of the cold end of the steam generator are converged and connected to the sewage expansion tank through the regular sewage discharge pipeline regulating valve of the steam generator, the side end of the steam generator is connected with the continuous sewage discharge pipeline of the steam generator, the continuous sewage discharge pipeline of the steam generator is installed with the continuous sewage discharge pipeline regulating valve of the steam generator, and the continuous sewage discharge pipeline of the steam generator is connected to the sewage expansion tank.

2. A device for reducing the failure rate of a steam generator blowdown electric valve according to claim 1, characterized in that: The regular sewage discharge pipeline at the bottom of the steam generator includes 4 pipelines, each of which is connected to the bottom of the steam generator, and each pipeline is installed with a valve.

3. A device for reducing the failure rate of a steam generator blowdown electric valve according to claim 2, characterized in that: The four pipelines include a first pipeline, a second pipeline, a third pipeline and a fourth pipeline.

4. A device for reducing the failure rate of a steam generator blowdown electric valve as claimed in claim 3, characterized in that: The first pipeline is provided with a second valve on the steam generator periodic sewage discharge pipeline.

5. A device for reducing the failure rate of a steam generator blowdown electric valve according to claim 3, characterized in that: The second pipeline is equipped with a third valve on the steam generator periodic sewage discharge pipeline.

6. A device for reducing the failure rate of a steam generator blowdown electric valve according to claim 3, characterized in that: The third pipeline is equipped with a fourth valve on the steam generator periodic sewage discharge pipeline.

7. A device for reducing the failure rate of a steam generator blowdown electric valve according to claim 3, characterized in that: The fourth pipeline is equipped with a fifth valve on the steam generator periodic sewage discharge pipeline.

Images