Nuclear power plant voltage stabilizer continuous exhaust system and method

Abstract

The invention belongs to the technical management field of nuclear power plants, and particularly relates to a continuous exhaust system and method for a nuclear power plant voltage stabilizer, the system comprises an automatic pressure relief main pipeline, an exhaust pipeline, a first electromagnetic isolation valve, a second electromagnetic isolation valve, a throttling orifice plate, a drain tank, a radioactive waste gas system, a voltage stabilizer and a pressure stabilizing valve; an automatic pressure relief main pipeline and a pressure stabilizer safety valve are arranged at the top of the pressure stabilizer, an exhaust pipeline is arranged on the automatic pressure relief main pipeline, and the exhaust pipeline is connected with a radioactive waste gas system through a drain tank; a throttling orifice plate is arranged on the automatic pressure relief main pipeline and located on the upstream of the exhaust pipeline. A first electromagnetic isolation valve, a second electromagnetic isolation valve and a pressure stabilizing valve are sequentially arranged on the exhaust pipeline; and the pressure stabilizing valve is an automatic downstream pressure regulating valve. Continuous and stable exhaust of the voltage stabilizer can be achieved, the exhaust frequency is greatly reduced, and meanwhile the operation reliability of the electromagnetic isolation valve is improved.

Description

Technical Field

[0001] The invention belongs to the field of nuclear power plant technical management, and in particular relates to a nuclear power plant pressurizer continuous exhaust system and method. Background Art

[0002] The main equipment of the primary circuit system of the AP1000 unit includes the reactor pressure vessel, main pump, steam generator and pressurizer, etc. The main pipelines include hot section, cold section, etc., and some safety-related instruments are configured to provide monitoring of key parameters. At the same time, interlock trigger signals are set to ensure nuclear safety.

[0003] The current exhaust method of the unit is to set two electromagnetic isolation valves and manual isolation valves in the exhaust pipeline of the stabilizer, among which the manual isolation valve is normally open, and the two electromagnetic isolation valves are normally closed. When the stabilizer needs to be exhausted during the operation of the unit, or when hydrogen removal is required at the end of the unit's life, the two electromagnetic isolation valves are opened in sequence, and the non-condensable gas at the top of the stabilizer is throttled by the throttling orifice plate and discharged to the containment drain tank through the exhaust pipeline. The non-condensable gas in the containment drain tank is then discharged to the atmosphere through the power plant chimney after delayed decay of inert gas through the radioactive waste gas treatment system.

[0004] According to the design requirements, the radioactive waste gas treatment system has a low capacity to receive non-condensable gas from the pressurizer (<5Nm 3 / h), and the flow through the exhaust throttle orifice has reached the critical flow (>3000Nm 3 / h), the buffer volume of the containment drain tank is small (<2Nm 3 ), which makes the single exhaust time of the regulator short, and the exhaust needs to be more than 200 times during the whole exhaust period, which in turn causes a large thermal shock to the pipeline, affects the reliability of the electromagnetic isolation valve, and increases the burden on the operating personnel.

[0005] As a means of improvement, if a flow control valve is added downstream of the electromagnetic isolation valve to control the flow, it is necessary to change the pressure and power supply of the control valve, which will have a great impact on the operation of the unit and there is insufficient space for implementation on site. Summary of the invention

[0006] The object of the present invention is to provide a nuclear power plant pressurizer continuous exhaust system and method, which can achieve continuous and stable exhaust of the pressurizer, greatly reduce the exhaust frequency, and improve the operating reliability of the electromagnetic isolation valve.

[0007] The technical solution to achieve the purpose of the present invention is:

[0008] A continuous exhaust system for a pressurizer in a nuclear power plant, the system comprising: an automatic pressure relief main line, an exhaust pipeline, a first electromagnetic isolation valve, a second electromagnetic isolation valve, a throttling orifice, a drain tank, a radioactive waste gas system, a pressurizer, and a pressure regulating valve; an automatic pressure relief main line and a pressurizer safety valve are arranged on the top of the pressurizer, an exhaust pipeline is arranged on the automatic pressure relief main line, and the exhaust pipeline is connected to the radioactive waste gas system via the drain tank; a throttling orifice is arranged on the automatic pressure relief main line, and the throttling orifice is located upstream of the exhaust pipeline; a first electromagnetic isolation valve, a second electromagnetic isolation valve, and a pressure regulating valve are arranged in sequence on the exhaust pipeline, the first electromagnetic isolation valve is located upstream of the second electromagnetic isolation valve, and the pressure regulating valve is located downstream of the second electromagnetic isolation valve; the pressure regulating valve is a post-valve pressure automatic regulating valve, and the pressure downstream of the pressure regulating valve is controlled by setting a post-valve pressure setting value of the pressure regulating valve to realize automatic matching of the exhaust flow of the pressurizer exhaust pipeline with the exhaust flow of the radioactive waste gas system.

[0009] The pressure stabilizing valve is a spring-loaded, pilot-operated, post-valve pressure automatic regulating valve.

[0010] The pressure stabilizing valve can be adjusted manually.

[0011] The pressure stabilizing valve is provided with a parallel pipeline, and a manual isolation valve is provided on the parallel pipeline.

[0012] The manual isolation valve is a stop valve, a gate valve or a ball valve.

[0013] A method for continuous exhaust of a nuclear power plant pressurizer, the method comprising:

[0014] Step 1: During normal operation of the unit, the first electromagnetic isolation valve and the second electromagnetic isolation valve are normally closed, and the pressure regulating valve remains fully open;

[0015] Step 2: When the pressure regulator needs to be exhausted, the second electromagnetic isolation valve is opened, and the non-condensable gas in the pipeline between the first electromagnetic isolation valve and the second electromagnetic isolation valve is discharged to the containment drain tank through the pressure regulating valve. As the pressure downstream of the pressure regulating valve rises, the opening of the pressure regulating valve becomes smaller until the pressure downstream of the pressure regulating valve stabilizes at the set value;

[0016] Step 3, open the first electromagnetic isolation valve of the exhaust pipeline, the non-condensable gas at the top of the regulator is throttled through the throttling orifice plate and then throttled through the pressure regulating valve into the drain tank, and as the pressure upstream of the pressure regulating valve increases, the opening of the pressure regulating valve is further reduced until the pressure downstream of the pressure regulating valve is stabilized at the set value;

[0017] Step 4: As the pressurizer is exhausted, the non-condensable gas content at the top of the pressurizer gradually decreases, the steam specific gravity gradually increases, the steam enters the drain tank for condensation after passing through the pressure regulating valve, and the non-condensable gas enters the radioactive waste gas system through the drain tank; with the increase in the steam specific gravity, the opening of the pressure regulating valve gradually increases;

[0018] Step 5: When the exhaust flow rate of the radioactive waste gas system continues to drop to a certain value and lasts for a period of time, the first electromagnetic isolation valve and the second electromagnetic isolation valve are closed in sequence, and the exhaust is completed.

[0019] The beneficial technical effects of the present invention are:

[0020] 1. The present invention provides a nuclear power plant pressurizer continuous exhaust system, which can achieve continuous and stable exhaust at the top of the pressurizer during normal operation of the unit and overhaul, reduce the number of repeated switching times of the electromagnetic isolation valve on the exhaust pipeline, and ensure that the downstream containment drain tank is not over-pressurized.

[0021] 2. The present invention provides a nuclear power plant pressurizer continuous exhaust system, which automatically controls the pressurizer exhaust flow rate by setting a post-valve pressure-stabilizing valve on the exhaust pipeline and setting an appropriate post-valve pressure, and controlling the pressure of the downstream drain tank, thereby greatly reducing the number of exhaust operations and improving the operating reliability of the electromagnetic isolation valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of a nuclear power plant pressurizer continuous exhaust system provided by the present invention;

[0023] In the figure: 1-first electromagnetic isolation valve; 2-second electromagnetic isolation valve; 3-throttling orifice plate; 4-drain tank; 5-radioactive waste gas system; 6-stabilizer; 7-pressure stabilizing valve. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0025] like Figure 1 As shown, the present invention provides a nuclear power plant pressurizer continuous exhaust system, comprising: an automatic pressure relief main line, an exhaust pipeline, a first electromagnetic isolation valve (1), a second electromagnetic isolation valve (2), a throttling orifice plate (3), a drain tank (4), a radioactive waste gas system (5), a pressurizer (6), and a pressure stabilizing valve (7).

[0026] An automatic pressure relief main line and a pressure stabilizer safety valve are arranged on the top of the pressure stabilizer (6); an exhaust pipeline is arranged on the automatic pressure relief main line, and the exhaust pipeline is connected to the radioactive waste gas system (5) via a drain tank (4); a throttling orifice plate (3) is arranged on the automatic pressure relief main line, and the throttling orifice plate (3) is located upstream of the exhaust pipeline; a first electromagnetic isolation valve (1), a second electromagnetic isolation valve (2), and a pressure stabilizing valve (7) are arranged in sequence on the exhaust pipeline, the first electromagnetic isolation valve (1) is located upstream of the second electromagnetic isolation valve (2), and the pressure stabilizing valve (7) is located downstream of the second electromagnetic isolation valve (2); the pressure stabilizing valve (7) is a valve rear pressure automatic regulating valve, which can automatically regulate the valve rear pressure to a set value without receiving a remote signal.

[0027] By setting a set value of the pressure after the pressure stabilizing valve (7), the pressure downstream of the pressure stabilizing valve (7) is controlled to achieve automatic matching of the exhaust flow of the exhaust pipeline of the pressure stabilizer (6) and the exhaust flow of the radioactive waste gas system (5).

[0028] In a specific embodiment, the pressure stabilizing valve (7) is a spring-loaded, pilot-operated, post-valve pressure automatic regulating valve.

[0029] In another specific embodiment, the design of the pressure regulating valve 7 should satisfy the ability to manually adjust the pressure after the valve, and can realize on-site manual forced opening. When manually forced to open, the exhaust mode of the pressure regulator is the same as the exhaust mode of the unit before the application of the present invention. When the applied pressure regulating valve cannot realize the manual forced opening function, the design should consider setting a parallel pipeline of the pressure regulating valve 7 on the exhaust pipeline, and setting a manual isolation valve on the parallel pipeline. The manual isolation valve can be a manual isolation valve with good sealing performance such as a stop valve, a gate valve, a ball valve, etc., so that it can be manually opened to restore the exhaust function of the pressure regulator when the pressure regulating valve loses its regulating ability and cannot be started.

[0030] According to a nuclear power plant pressurizer continuous exhaust system provided by the present invention, the present invention also provides a nuclear power plant pressurizer continuous exhaust method, which specifically includes the following steps:

[0031] Step 1: During normal operation of the unit (pressure is about 15.4 MPa), the first electromagnetic isolation valve (1) and the second electromagnetic isolation valve (2) on the exhaust pipeline are normally closed, and the downstream pressure regulating valve (7) remains fully open because the downstream pressure is lower than the set value.

[0032] Step 2: When the pressure regulator (6) needs to be exhausted, the second electromagnetic isolation valve (2) downstream is first opened. At this time, the non-condensable gas in the pipeline between the first electromagnetic isolation valve (1) and the second electromagnetic isolation valve (2) is discharged to the containment drain tank (4) through the pressure regulating valve (7). As the pressure downstream of the pressure regulating valve (7) rises, the opening of the pressure regulating valve (7) becomes smaller until the pressure downstream of the pressure regulating valve (7) stabilizes at the set value.

[0033] Step 3, then open the first electromagnetic isolation valve (1) of the exhaust pipeline. At this time, the non-condensable gas at the top of the stabilizer is throttled through the throttling orifice (3) and then throttled through the pressure regulating valve (7) to enter the drain tank (4) in the containment. As the pressure upstream of the pressure regulating valve (7) increases, the opening of the pressure regulating valve is further reduced until the pressure downstream of the pressure regulating valve (7) stabilizes at the set value.

[0034] Step 4: As the venting of the pressurizer (6) proceeds, the non-condensable gas content at the top of the pressurizer (6) gradually decreases, the steam specific gravity gradually increases, the steam enters the containment drain tank (4) through the pressure regulating valve (7) to condense, and the non-condensable gas enters the radioactive waste gas system (5) through the drain tank (4); as the steam specific gravity increases, the opening of the pressure regulating valve (7) gradually increases.

[0035] Step 5: When the exhaust flow rate of the radioactive waste gas system (5) continues to drop to a certain value and lasts for a period of time, the first electromagnetic isolation valve (1) and the second electromagnetic isolation valve (2) are closed in sequence, and the exhaust is completed.

[0036] The present invention is described in detail above with reference to the accompanying drawings and embodiments, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the present invention. The contents not described in detail in the present invention can adopt the existing technology.

Claims

1. A nuclear power plant pressurizer continuous exhaust system, characterized in that: The system comprises: an automatic pressure relief main line, an exhaust pipeline, a first electromagnetic isolation valve (1), a second electromagnetic isolation valve (2), a throttling orifice plate (3), a drain tank (4), a radioactive waste gas system (5), a pressure regulator (6), and a pressure regulating valve (7); an automatic pressure relief main line and a pressure regulator safety valve are arranged on the top of the pressure regulator (6); an exhaust pipeline is arranged on the automatic pressure relief main line, and the exhaust pipeline is connected to the radioactive waste gas system (5) via the drain tank (4); a throttling orifice plate (3) is arranged on the automatic pressure relief main line, and the throttling orifice plate (3) is located at The exhaust pipeline is upstream; a first electromagnetic isolation valve (1), a second electromagnetic isolation valve (2), and a pressure regulating valve (7) are sequentially arranged on the exhaust pipeline, the first electromagnetic isolation valve (1) is located upstream of the second electromagnetic isolation valve (2), and the pressure regulating valve (7) is located downstream of the second electromagnetic isolation valve (2); the pressure regulating valve (7) is an automatic regulating valve for the after-valve pressure, and the pressure downstream of the pressure regulating valve (7) is controlled by setting a set value of the after-valve pressure of the pressure regulating valve (7) to achieve automatic matching of the exhaust flow of the exhaust pipeline of the regulator (6) and the exhaust flow of the radioactive waste gas system (5).

2. A nuclear power plant pressurizer continuous exhaust system according to claim 1, characterized in that: The pressure stabilizing valve (7) is a spring-loaded, pilot-operated, post-valve pressure automatic regulating valve.

3. A nuclear power plant pressurizer continuous exhaust system according to claim 1, characterized in that: The pressure stabilizing valve (7) can be adjusted manually.

4. A nuclear power plant pressurizer continuous exhaust system according to claim 1, characterized in that: The pressure stabilizing valve (7) is provided with a parallel pipeline, and a manual isolation valve is provided on the parallel pipeline.

5. A nuclear power plant pressurizer continuous exhaust system according to claim 4, characterized in that: The manual isolation valve is a stop valve, a gate valve or a ball valve.

6. A method for continuous exhaust of a nuclear power plant pressurizer, used in a continuous exhaust system of a nuclear power plant pressurizer according to claim 1, characterized in that: The method comprises: Step 1: During normal operation of the unit, the first electromagnetic isolation valve (1) and the second electromagnetic isolation valve (2) are normally closed, and the pressure regulating valve (7) is kept fully open; Step 2: When the pressure regulator (6) needs to be exhausted, the second electromagnetic isolation valve (2) is opened, and the non-condensable gas in the pipeline between the first electromagnetic isolation valve (1) and the second electromagnetic isolation valve (2) is discharged to the containment drain tank (4) through the pressure regulating valve (7). As the pressure downstream of the pressure regulating valve (7) rises, the opening of the pressure regulating valve (7) becomes smaller until the pressure downstream of the pressure regulating valve (7) stabilizes at a set value; Step 3, open the first electromagnetic isolation valve (1) of the exhaust pipeline, and the non-condensable gas at the top of the pressure regulator (6) is throttled through the throttling orifice plate (3) and then throttled through the pressure regulating valve (7) into the drain tank (4). As the pressure upstream of the pressure regulating valve (7) increases, the opening of the pressure regulating valve is further reduced until the pressure downstream of the pressure regulating valve (7) is stabilized at the set value; Step 4: As the pressurizer (6) exhausts, the non-condensable gas content at the top of the pressurizer (6) gradually decreases, the steam specific gravity gradually increases, the steam enters the drain tank (4) for condensation after passing through the pressure regulating valve (7), and the non-condensable gas enters the radioactive waste gas system (5) through the drain tank (4); as the steam specific gravity increases, the opening of the pressure regulating valve (7) gradually increases; Step 5: When the exhaust flow rate of the radioactive waste gas system (5) continues to drop to a certain value and lasts for a period of time, the first electromagnetic isolation valve (1) and the second electromagnetic isolation valve (2) are closed in sequence, and the exhaust is completed.

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