An exhaust device for a nuclear island drain exhaust system of a nuclear power plant

Abstract

The present invention belongs to the technical field of nuclear power plant equipment maintenance, and specifically relates to an exhaust device of a nuclear island drain and exhaust system of a nuclear power plant, which is achieved by connecting a set of exhaust devices in parallel on the exhaust pipeline at the top of the nuclear island pressurizer equipment, and by adding two tees and isolation valves, vacuum pumps (vacuum ejectors) and other devices on the original pipeline. The vacuum ejector is powered by compressed air, and the exhaust gas mixed with the gas of a circuit returns to the nuclear island drain and exhaust system. The device of the present invention for the flushing stage of a circuit after the overhaul of a nuclear power plant is equipped with a set of exhaust devices of the nuclear island drain and exhaust system, and a vacuum ejector is added to the exhaust pipeline, and the gas of the circuit is discharged through the vacuum ejector, and the circuit is filled with water. The vacuum ejector is powered by maintenance compressed air, and the exhaust gas mixed with the gas of the circuit returns to the nuclear island drain and exhaust system. When the pressurizer liquid level reaches full water, the pressurizer exhaust valve and the isolation valve of the vacuum ejector are closed.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear power plant equipment maintenance, and in particular relates to an exhaust device of a nuclear island drain exhaust system of a nuclear power plant. Background Art

[0002] After the nuclear island main system of the M310 model is drained to the low water level, when it is re-flushed, the air in the pipes and equipment cannot be completely discharged from the system due to the influence of the inverted U-tube of the steam generator and the circular top cover of the pressure vessel. It is necessary to drive out the air of the main system through the method of static exhaust-dynamic exhaust-combined exhaust. Among them, dynamic exhaust and combined exhaust require the three reactor coolant pumps (hereinafter referred to as main pumps) to be activated in sequence.

[0003] When the main pump is under the low-pressure platform of the main system, the auxiliary thrust bearing bears the vertical downward load of the main pump axis. However, some main pumps in the power plant are not designed with a top shaft oil system for the auxiliary thrust bearing, so the auxiliary bearing will bear a large load during the pump startup. In addition, there is a common mode design problem in the auxiliary thrust bearing of the main pump. When the main pump is started on a low-pressure platform, the risk of wear of the motor auxiliary thrust bearing is relatively high. The power plant has experienced abnormal wear of the auxiliary thrust bearing of the main pump. Summary of the invention

[0004] In view of the above shortcomings, the purpose of the present invention is to provide an exhaust device for the nuclear island drain exhaust system of a nuclear power plant, by connecting a set of exhaust devices in parallel on the exhaust pipeline at the top of the nuclear island pressurizer equipment, and by adding two tees and isolation valves, vacuum pumps (vacuum ejectors) and other devices on the original pipeline. The vacuum ejector is powered by compressed air, and the exhaust mixed with the gas in the primary circuit returns to the nuclear island drain exhaust system.

[0005] The technical solution of the present invention is as follows:

[0006] An exhaust device of a nuclear power plant nuclear island drain exhaust system, a vacuum ejector inlet isolation valve A8, a vacuum ejector inlet isolation valve B, a vacuum ejector, a maintenance compressed air quick connector, a vacuum ejector outlet isolation valve A, a vacuum ejector outlet isolation valve B, an exhaust pipeline isolation valve, a tee A and a tee B;

[0007] The pressure vessel is connected to the steam generator through the main pipeline. A pipeline is branched from the main pipeline and connected to the pressurizer. The top of the pressurizer is connected to the pressurizer bleed isolation valve through the pressurizer bleed valve, and finally leads to the nuclear island drain exhaust system.

[0008] A tee A and then a tee B are first set between the pressurizer vent isolation valve and the nuclear island drain exhaust system.

[0009] One pipeline of Tee A is connected to one end of Tee B through the exhaust pipeline isolation valve. Another pipeline of Tee A is connected to the vacuum ejector and then connected to the other end of Tee B. The third end of Tee B is connected to the nuclear island drain exhaust system.

[0010] A vacuum ejector inlet isolation valve A is provided between the tee A and the vacuum ejector.

[0011] A vacuum ejector inlet isolation valve B is provided between the vacuum ejector inlet isolation valve A and the vacuum ejector.

[0012] A vacuum ejector outlet isolation valve A is provided between the vacuum ejector and the tee B.

[0013] A vacuum ejector outlet isolation valve B is arranged between the vacuum ejector outlet isolation valve A and the three-way B.

[0014] The vacuum ejector is also connected to the maintenance compressed air quick connector.

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

[0016] The device for flushing the primary circuit after overhaul of a nuclear power plant of the present invention uses a set of exhaust devices of the nuclear island drain exhaust system, and a vacuum ejector is added to the exhaust pipeline to discharge the primary circuit gas through the vacuum ejector to fill the primary circuit with water.

[0017] The vacuum ejector is powered by maintenance compressed air, and the exhaust mixed with the gas in the primary circuit returns to the nuclear island drain exhaust system. When the pressurizer liquid level reaches full water, close the pressurizer exhaust valve and the isolation valve of the vacuum ejector.

[0018] The invention can avoid abnormal wear and even burning of the auxiliary bearings of the main pump when starting at a low-pressure platform of the main system, reduce the number of times the main pump is started at a low-pressure platform, improve the equipment reliability of the main pump, and at the same time significantly save overhaul time and improve the economy of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the system layout of the present invention.

[0020] In the figure, 1-pressure vessel; 2-pressurizer; 3-steam generator; 4-main pipeline; 5-main pipeline half-pipe water level; 6-pressurizer bleed valve; 7-pressurizer bleed isolation valve; 8-vacuum ejector inlet isolation valve A; 9-vacuum ejector inlet isolation valve B; 10-vacuum ejector; 11-maintenance compressed air quick connector 12-vacuum ejector outlet isolation valve A; 13-vacuum ejector outlet isolation valve B; 14-exhaust pipeline isolation valve; 15-tee A; 16-tee B. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0022] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention.

[0023] As shown in the figure, an exhaust device of a nuclear power plant nuclear island drain exhaust system includes a vacuum ejector inlet isolation valve A8, a vacuum ejector inlet isolation valve B9, a vacuum ejector 10, a maintenance compressed air quick connector 11, a vacuum ejector outlet isolation valve A12, a vacuum ejector outlet isolation valve B13, an exhaust pipeline isolation valve 14, a tee A15 and a tee B16.

[0024] The pressure vessel 1 is connected to the steam generator 3 through the main pipeline 4, a pipeline is branched from the main pipeline 4 and connected to the pressurizer 2, the top of the pressurizer is connected to the pressurizer bleed isolation valve 7 through the pressurizer bleed valve 6, and finally leads to the nuclear island drain exhaust system;

[0025] A three-way A15 and a three-way B16 are firstly provided between the pressurizer vent isolation valve 7 and the nuclear island drain exhaust system;

[0026] One pipeline of tee A15 is connected to one end of tee B16 through exhaust pipeline isolation valve 14, another pipeline of tee A15 is connected to vacuum ejector 10, and then connected to the other end of tee B16; the third end of tee B16 is connected to nuclear island drain exhaust system.

[0027] A vacuum ejector inlet isolation valve A8 is provided between the tee A15 and the vacuum ejector 10;

[0028] A vacuum ejector inlet isolation valve B9 is provided between the vacuum ejector inlet isolation valve A8 and the vacuum ejector 10;

[0029] A vacuum ejector outlet isolation valve A12 is provided between the vacuum ejector 10 and the tee B16;

[0030] A vacuum ejector outlet isolation valve B13 is provided between the vacuum ejector outlet isolation valve A12 and the three-way valve B16;

[0031] The vacuum ejector 10 is also connected to a maintenance compressed air quick connector.

[0032] The device is arranged in the reactor containment. On the basis of the pipeline of the original nuclear island drain and exhaust system, the nuclear island drain and exhaust pipeline downstream of the original stabilizer vent isolation valve 7 is firstly cut open, and the vacuum ejector 10, the inlet and outlet isolation valves 8 / 9 / 12 / 13 and the associated pipelines are welded to the tee 15 / 16 by welding two new tees 15 / 16, and at the same time, a new exhaust pipeline isolation valve 14 is welded upstream of the tee 16 returning to the original pipeline.

[0033] After the low water level maintenance is completed and the pressure vessel is loaded, close the top cover and the manhole of the stabilizer according to the normal operating process. At this time, the one-circuit system has been closed, and the one-circuit is discharged to about half the pipe water level 5, open the stabilizer vent valve 6 and the stabilizer vent isolation valve 7, open the inlet and outlet isolation valves 8 / 9 / 12 / 13 of the vacuum ejector 10, close the exhaust pipeline isolation valve 14, connect the maintenance compressed air and the vacuum ejector 10 through the quick connector, start the vacuum ejector to discharge the gas of the one-circuit to the nuclear island drain exhaust system, and after the pressure drops to the target pressure, open the one-circuit water inlet valve to fill the one-circuit with water. At this time, keep the vacuum ejector running until the inside of the stabilizer is full of water, disconnect the maintenance compressed air, and close the stabilizer vent valve 6 and the stabilizer vent isolation valve 7.

[0034] The above process realizes the operation of exhausting air and filling water in one circuit by adding an exhaust device to the nuclear island drain and exhaust system and connecting a vacuum ejector in parallel to the original system, thus avoiding the use of the main pump for dynamic exhaust and connecting exhaust of the system, effectively avoiding the possibility of wear of the auxiliary thrust bearing of the main pump on the low-pressure platform, and improving the safety of the unit; at the same time, it also greatly shortens the time of filling water in the first circuit and improves the economic efficiency of the unit operation.

[0035] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0036] It should be noted that, in the description of the present invention, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, the meaning of "plurality" refers to at least two.

[0037] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0038] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

[0039] In the drawings of the embodiments disclosed in the present invention, only the methods related to the embodiments disclosed in the present invention are involved, and other methods can refer to the general design. In the case of no conflict, the same embodiment and different embodiments of the present invention can be combined with each other;

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An exhaust device for a nuclear power plant nuclear island drain exhaust system, a vacuum ejector inlet isolation valve A, a vacuum ejector inlet isolation valve B, a vacuum ejector, a maintenance compressed air quick connector, a vacuum ejector outlet isolation valve A, a vacuum ejector outlet isolation valve B, an exhaust pipeline isolation valve, a tee A and a tee B; Features: The pressure vessel is connected to the steam generator through the main pipeline, a pipeline is branched from the main pipeline and connected to the pressurizer, the top of the pressurizer is connected to the pressurizer bleed isolation valve through the pressurizer bleed valve, and finally leads to the nuclear island drain exhaust system; A tee A is first set between the pressurizer vent isolation valve and the nuclear island drain exhaust system, and then a tee B is set; One pipeline of tee A is connected to one end of tee B through the exhaust pipeline isolation valve. Another pipeline of tee A is connected to the vacuum ejector and then connected to the other end of tee B. The third end of tee B is connected to the nuclear island drain exhaust system. A vacuum ejector inlet isolation valve A is provided between the tee A and the vacuum ejector; A vacuum ejector inlet isolation valve B is provided between the vacuum ejector inlet isolation valve A and the vacuum ejector; A vacuum ejector outlet isolation valve A is provided between the vacuum ejector and the tee B; A vacuum ejector outlet isolation valve B is provided between the vacuum ejector outlet isolation valve A and the three-way B; The vacuum ejector is also connected to the maintenance compressed air quick connector.

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