阅读说明：本技术 一种余热排出系统及方法、核电系统 (Waste heat discharge system and method and nuclear power system ) 是由 皮月 侯婷 姚亦珺 李博 于 2021-07-06 设计创作，主要内容包括：本发明提供一种余热排出系统及方法、核电系统,余热排出系统中,主管连接于反应堆冷却剂系统的热段和冷段之间,小流量管连接于主管的两个连通口之间,其上设有自力式压差调节阀,泵前取压管设于主管泵前段和调节阀之间,泵后取压管设于主管泵后段和调节阀之间,当主管上的泵前隔离阀开启且泵后隔离阀关闭,或冷段中冷却剂的压力升高时,调节阀压差大于设定值,以使其自动开启,实现小流量管与主管的连通,当主管上的泵前泵后隔离阀均开启时,调节阀压差小于设定值,以使其关闭,实现小流量管与主管的断开。由此,本系统能够实现在不需要额外的仪控逻辑配置的前提下,小流量管线在不同需求工况下的自动启闭,从而具有结构简单、可靠性高的优点。(The invention provides a waste heat discharge system and a method as well as a nuclear power system, wherein in the waste heat discharge system, a main pipe is connected between a hot section and a cold section of a reactor coolant system, a small flow pipe is connected between two communication ports of the main pipe, a self-operated pressure difference regulating valve is arranged on the small flow pipe, a front pump pressure tapping pipe is arranged between the front section of a main pipe pump and the regulating valve, a rear pump pressure tapping pipe is arranged between the rear section of the main pipe pump and the regulating valve, when a front pump isolation valve on the main pipe is opened and a rear pump isolation valve is closed, or the pressure of coolant in the cold section is increased, the pressure difference of the regulating valve is larger than a set value so as to be automatically opened, the small flow pipe is communicated with the main pipe, and when the front pump isolation valve and the rear pump isolation valve on the main pipe are both opened, the pressure difference of the regulating valve is smaller than the set value so as to be closed, and the small flow pipe is disconnected with the main pipe. Therefore, the system can realize the automatic opening and closing of the small-flow pipeline under different requirement working conditions on the premise of not needing additional instrument control logic configuration, thereby having the advantages of simple structure and high reliability.)

1. A residual heat removal system, comprising: a main pipe, a small flow pipe (20), a pressure tapping pipe before the pump (21) and a pressure tapping pipe after the pump (22),

the main pipe is connected between a hot section (10) and a cold section (30) of a reactor coolant system loop, a first isolation valve (001), a circulating pump (002), a heat exchanger (004) and a second isolation valve (005) are sequentially arranged on the main pipe along the flow direction of coolant from the hot section (10) to the cold section (30),

the small flow pipe (20) is connected between a first communicating port and a second communicating port of the main pipe, the first communicating port is positioned between the first isolating valve (001) and the circulating pump (002), the second communicating port is positioned between the heat exchanger (004) and the second isolating valve (005), the small flow pipe (20) is provided with a self-operated differential pressure regulating valve (006),

the main pipe is divided into a pump front section and a pump rear section by the circulating pump (002),

the pump front pressure tapping pipe (21) is arranged between the pump front section of the main pipe and the self-operated differential pressure regulating valve (006) and is used for guiding the pressure P1 of the coolant in the pump front section into the self-operated differential pressure regulating valve (006),

the pump rear pressure taking pipe (22) is arranged between the pump rear section of the main pipe and the self-operated differential pressure regulating valve (006) and is used for guiding the pressure P2 of the coolant in the pump rear section into the self-operated differential pressure regulating valve (006),

when the first isolation valve (001) is opened and the second isolation valve (005) is closed or the pressure of the coolant in the cold section (30) of the reactor coolant system loop is increased, the pressure difference delta P is P2-P1 is larger than a set value, so that the self-operated pressure difference regulating valve (006) is opened to realize the communication between the small flow pipe (20) and the main pipe,

when the first isolation valve (001) and the second isolation valve (005) are both opened, the pressure difference delta P is P2-P1 smaller than a set value, so that the self-operated pressure difference regulating valve (006) is closed, and the small flow pipe (20) is disconnected from the main pipe.

2. The residual heat removal system according to claim 1, wherein the pre-pump pressure tapping pipe (21) is arranged between the first communication port of the main pipe and the self-operated differential pressure regulating valve (006).

3. The residual heat removal system according to claim 1, wherein the post-pump pressure tapping pipe (22) is provided between a third communication port of the main pipe, which is a position between the circulation pump (002) and the heat exchanger (004), and the self-operated differential pressure regulating valve (006).

4. Residual heat removal system according to claim 1, characterized in that the main pipe is further provided with a check valve (003), the check valve (003) being a location between the circulation pump (002) and the heat exchanger (004).

5. The residual heat removal system according to any one of claims 1 to 4, wherein the self-operated differential pressure regulating valve (006) comprises a main valve, a pilot valve and a valve stem,

the main valve is provided with a main valve cavity, a valve seat is arranged in the main valve cavity, the main valve cavity is divided into a liquid inlet cavity and a liquid outlet cavity by the valve seat, the liquid inlet cavity is provided with a liquid inlet which is connected with the front section of the main pipe pump, the liquid outlet cavity is provided with a liquid outlet which is connected with the rear section of the main pipe pump, the valve seat is provided with a valve port which is communicated with the liquid inlet cavity and the liquid outlet cavity,

the pilot valve is provided with a membrane cavity, a membrane is arranged in the membrane cavity, the membrane cavity is divided into an upper membrane cavity and a lower membrane cavity by the membrane, the pressure tapping pipe (21) in front of the pump is communicated with the lower membrane cavity, the pressure tapping pipe (22) behind the pump is communicated with the upper membrane cavity,

one end of the valve rod is connected with the diaphragm through a spring, the other end of the valve rod is provided with a valve core matched with the valve port of the valve seat, the set value is the elastic force of the spring,

when the pressure difference delta P between the upper end and the lower end of the diaphragm is smaller than the elastic force of the spring, the valve core closes the valve port to realize the automatic closing of the self-operated pressure difference regulating valve (006),

when the pressure difference delta P is smaller than the elastic force of the spring, the valve rod moves upwards to drive the valve core to open the valve port, so that the self-operated pressure difference regulating valve (006) is automatically opened.

6. A method of removing excess heat from a reactor coolant system using a system according to any of claims 1 to 5, comprising the steps of:

the first isolation valve (001) is opened, the second isolation valve (005) is closed to communicate the main pipe with the small flow pipe (20), the circulating pump (002) is started, the coolant in the circulation formed by the small flow pipe (20) and the main pipe is heated to a set value by the power of the circulating pump (002),

and opening a second isolation valve (005) to disconnect the main pipe from the small flow pipe (20) and form circulation with the reactor coolant system, and pumping the coolant in the hot section (10) of the reactor coolant system loop into a heat exchanger (004) by the power of a circulating pump (002) to be cooled and then delivering the coolant to the hot section (10) of the reactor coolant system loop.

7. A nuclear power system comprising a reactor coolant system and a residual heat removal system according to any one of claims 1 to 5.

Technical Field

The invention particularly relates to a waste heat discharge system and method and a nuclear power system.

Background

At present, most of the widely-operated domestic second-generation nuclear power plants are reactor types which continue the nuclear power technology of a French pressurized water reactor, and other heat discharge systems are provided with small-flow pipelines without any measuring device or other devices such as valves and the like. The small flow line is used for preheating the waste heat discharge system and protecting the pump when the valve of the return pipeline is closed, the pressure of the return pipeline suddenly rises and the like. When the waste heat discharge system cools the reactor, the small flow pipeline always has medium for circulation. This phenomenon results in a loss of part of the circulating cooling flow, further resulting in a reduction in the cooling capacity of the system and a deterioration in the efficiency.

Aiming at the problem, the waste heat discharge system is improved by a certain third-generation nuclear power technology. A pneumatic regulating valve which is controlled by logic is arranged on a small flow pipeline. When the flow of the main loop is reduced to a certain value or zero, the pneumatic regulating valve is opened: during system warm-up, the main loop return line is closed, the main loop flow is zero, and the pump is cycled on the small flow line. When the waste heat discharge system is preheated to the temperature difference between the waste heat discharge system and a loop, which is less than 60 ℃, the access condition of the loop is achieved, the isolation valve of the waste heat discharge system returning to the main pipeline is opened, the pump flow rises, and after the main loop flow exceeds a certain value, the pneumatic regulating valve is closed. And then the residual heat removal system brings the reactor to a cold shutdown state.

The improvement measures effectively solve the problem of efficiency reduction caused by the small-flow pipeline of the traditional waste heat discharge system. But the method needs related instrumentation and control logic measures to realize the method, and has complex device and poor reliability.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a waste heat removal system for improving the reliability and the economical efficiency of the system aiming at the defects in the prior art, and correspondingly provide a method for removing waste heat in a reactor coolant system by using the system, and a nuclear power system with the waste heat removal system.

The technical scheme adopted for solving the technical problem of the invention is as follows:

the invention provides a waste heat discharge system, comprising: a main pipe, a small flow pipe, a pressure tapping pipe before the pump and a pressure tapping pipe after the pump,

the main pipe is connected between a hot section and a cold section of a reactor coolant system loop, a first isolation valve, a circulating pump, a heat exchanger and a second isolation valve are sequentially arranged on the main pipe along the flow direction of coolant from the hot section to the cold section,

the small flow pipe is connected between a first communicating port and a second communicating port of the main pipe, the first communicating port is positioned between the first isolating valve and the circulating pump, the second communicating port is positioned between the heat exchanger and the second isolating valve, the small flow pipe is provided with a self-operated differential pressure regulating valve,

the main pipe is divided into a pump front section and a pump rear section by the circulating pump,

the pump front pressure tapping pipe is arranged between the pump front section of the main pipe and the self-operated differential pressure regulating valve and is used for guiding the pressure P1 of the coolant in the pump front section into the self-operated differential pressure regulating valve,

the pump rear pressure tapping pipe is arranged between the pump rear section of the main pipe and the self-operated differential pressure regulating valve and is used for leading the pressure P2 of the coolant in the pump rear section into the self-operated differential pressure regulating valve,

when the first isolating valve is opened and the second isolating valve is closed, or the pressure of the coolant in the cold section of the loop of the reactor coolant system is increased, the pressure difference delta P is greater than the set value P2-P1, so that the self-operated pressure difference regulating valve is opened to realize the communication between the small flow pipe and the main pipe,

when the first isolation valve and the second isolation valve are both opened, the pressure difference delta P is P2-P1 and is smaller than a set value, so that the self-operated pressure difference regulating valve is closed, and the small flow pipe is disconnected from the main pipe.

Optionally, the pre-pump pressure tapping pipe is arranged between the first communication port of the main pipe and the self-operated differential pressure regulating valve.

Optionally, the post-pump pressure tapping pipe is arranged between a third communication port of the main pipe and the self-operated differential pressure regulating valve, and the third communication port is a position between the circulating pump and the heat exchanger.

Optionally, the main pipe is further provided with a check valve, the check valve being a position between the circulation pump and the heat exchanger.

Optionally, the self-operated differential pressure regulating valve comprises a main valve, a pilot valve and a valve rod,

the main valve is provided with a main valve cavity, a valve seat is arranged in the main valve cavity, the main valve cavity is divided into a liquid inlet cavity and a liquid outlet cavity by the valve seat, the liquid inlet cavity is provided with a liquid inlet which is connected with the front section of the main pipe pump, the liquid outlet cavity is provided with a liquid outlet which is connected with the rear section of the main pipe pump, the valve seat is provided with a valve port which is communicated with the liquid inlet cavity and the liquid outlet cavity,

the guide valve is provided with a membrane cavity, a membrane is arranged in the membrane cavity, the membrane divides the membrane cavity into an upper membrane cavity and a lower membrane cavity, the pressure tapping pipe before the pump is communicated with the lower membrane cavity, the pressure tapping pipe after the pump is communicated with the upper membrane cavity,

one end of the valve rod is connected with the diaphragm through a spring, the other end of the valve rod is provided with a valve core matched with the valve port of the valve seat, the set value is the elastic force of the spring,

when the pressure difference delta P between the upper end and the lower end of the diaphragm is smaller than the elastic force of the spring, the valve core closes the valve port to realize the automatic closing of the self-operated pressure difference regulating valve,

when the pressure difference delta P is smaller than the elastic force of the spring, the valve rod moves upwards to drive the valve core to open the valve port, so that the self-operated pressure difference regulating valve is automatically opened.

The invention also provides a method for discharging waste heat in a reactor coolant system by using the system, which comprises the following steps:

opening the first isolating valve, closing the second isolating valve to communicate the main pipe with the small flow pipe, starting the circulating pump to heat the coolant in the circulation formed by the small flow pipe and the main pipe to the set value by the power of the circulating pump,

and opening a second isolation valve to disconnect the main pipe from the small flow pipe and form circulation with the reactor coolant system, and pumping the coolant in the hot section of the loop of the reactor coolant system into the heat exchanger by the power of the circulating pump to be cooled and then delivering the coolant to the hot section of the loop of the reactor coolant system.

The invention also provides a nuclear power system which comprises a reactor coolant system and the waste heat discharge system.

According to the invention, the pressure type differential pressure regulating valve is arranged on the small flow pipe, and the pressure before the pump and the pressure after the pump of the circulating pump on the waste heat discharge main pipeline are led into the pressure type differential pressure regulating valve, so that the state of the pressure type differential pressure regulating valve can be automatically regulated according to the pump lift of the pump, and the on-off of the small flow pipe is automatically controlled. Under the preheating working condition, the first isolating valve is opened, the second isolating valve is closed, the pressure behind the pump is large, the lift of the circulating pump exceeds the set value of the pressure type differential pressure regulating valve, the pressure type differential pressure regulating valve is automatically opened, the small flow pipeline is communicated, and the coolant is internally circulated between the waste heat discharging main pipeline and the small flow pipeline through the circulating pump until the coolant in the internal circulation is heated to the temperature requirement of the system communicated with a reactor coolant system by the circulating pump; under the waste heat discharge working condition, the first isolation valve and the second isolation valve are both opened, the pressure difference between the front pump and the rear pump of the pump is reduced at the moment, when the lift of the circulating pump is reduced to be smaller than the set value of the pressure type pressure difference regulating valve, the pressure type pressure difference regulating valve is automatically closed, the small flow pipeline is isolated, the coolant in the hot section of the reactor coolant system is pumped into the heat exchanger on the waste heat discharge main pipeline through the circulating pump, and is sent to the cold section of the reactor coolant system after being cooled, so that the waste heat in the reactor coolant system is discharged. In addition, when the system has accidents in the waste heat discharging working process, such as the pressure of a cold section of a reactor coolant system loop suddenly rises or a second isolating valve is closed, the resistance which needs to be overcome by a circulating pump is increased, the flow is reduced, the lift rises until the pressure exceeds the set value of a pressure type differential pressure regulating valve, the pressure type differential pressure regulating valve is opened, small flow pipes are communicated in a line mode, the circulating pump is converted into the internal circulation of the system from the circulation of the reactor coolant system, and the circulating pump cannot be blocked or damaged, so that the safety state of equipment and the system is maintained.

Therefore, the system realizes the automatic opening and closing of the small flow pipeline under different requirement working conditions on the premise of not needing additional instrument control logic configuration, can realize the preheating function of the waste heat discharge system and the protection function of the circulating pump, and can realize the automatic isolation of the small flow pipeline when executing normal cooling. Therefore, the system has the advantages of simple structure and high reliability, and simultaneously has direct improvement on the cooling capacity of the system, thereby having remarkable economic benefit; in addition, the safety of the circulating pump is also ensured.

Drawings

Fig. 1 is a schematic structural diagram of a waste heat removal system provided in embodiment 1 of the present invention;

FIG. 2 is a schematic structural view of a self-operated differential pressure regulating valve;

fig. 3 is a characteristic curve diagram of the head of the waste heat removal system of a certain plant.

In the figure: 10. a hot stage; 20. a small flow tube; 21. a pressure pipe is taken before the pump; 22. a pipe is taken out after the pump; 30. a cold stage; 001. a first isolation valve; 002. a circulation pump; 003. a check valve; 004. a heat exchanger; 005. a second isolation valve; 006. self-operated differential pressure regulating valve.

Detailed Description

The technical solutions in the present invention will be described clearly and completely with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the scope of the present invention.

In the description of the present invention, it should be noted that the indication of orientation or positional relationship, such as "on" or the like, is based on the orientation or positional relationship shown in the drawings, and is only for convenience and simplicity of description, and does not indicate or imply that the device or element referred to must be provided with a specific orientation, constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "connected," "disposed," "mounted," "fixed," and the like are to be construed broadly, e.g., as being fixedly or removably connected, or integrally connected; either directly or indirectly through intervening media, or may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases for those skilled in the art.

The invention provides a waste heat discharge system, comprising: a main pipe, a small flow pipe, a pressure tapping pipe before the pump and a pressure tapping pipe after the pump,

the main pipe is connected between a hot section and a cold section of a reactor coolant system loop, a first isolation valve, a circulating pump, a heat exchanger and a second isolation valve are sequentially arranged on the main pipe along the flow direction of coolant from the hot section to the cold section,

the small flow pipe is connected between a first communicating port and a second communicating port of the main pipe, the first communicating port is positioned between the first isolating valve and the circulating pump, the second communicating port is positioned between the heat exchanger and the second isolating valve, the small flow pipe is provided with a self-operated differential pressure regulating valve,

the main pipe is divided into a pump front section and a pump rear section by the circulating pump,

the pump front pressure tapping pipe is arranged between the pump front section of the main pipe and the self-operated differential pressure regulating valve and is used for guiding the pressure P1 of the coolant in the pump front section into the self-operated differential pressure regulating valve,

the pump rear pressure tapping pipe is arranged between the pump rear section of the main pipe and the self-operated differential pressure regulating valve and is used for leading the pressure P2 of the coolant in the pump rear section into the self-operated differential pressure regulating valve,

when the first isolating valve is opened and the second isolating valve is closed, or the pressure of the coolant in the cold section of the loop of the reactor coolant system is increased, the pressure difference P which is P2-P1 is greater than a set value, so that the self-operated pressure difference regulating valve is opened to realize the communication between the small flow pipe and the main pipe,

when the first isolation valve and the second isolation valve are both opened, the pressure difference P which is P2-P1 is smaller than a set value, so that the self-operated pressure difference regulating valve is closed, and the small flow pipe is disconnected from the main pipe.

The invention also provides a method for discharging waste heat in a reactor coolant system by using the system, which comprises the following steps:

opening the first isolating valve, closing the second isolating valve to communicate the main pipe with the small flow pipe, starting the circulating pump to heat the coolant in the circulation formed by the small flow pipe and the main pipe to the set value by the power of the circulating pump,

and opening a second isolation valve to disconnect the main pipe from the small flow pipe and form circulation with the reactor coolant system, and pumping the coolant in the hot section of the loop of the reactor coolant system into the heat exchanger by the power of the circulating pump to be cooled and then delivering the coolant to the hot section of the loop of the reactor coolant system.

The invention also provides a nuclear power system which comprises a reactor coolant system and the waste heat discharge system.

Example 1:

as shown in fig. 1, the present embodiment provides a waste heat removal system, including: a main pipe, a small flow pipe 20, a pressure tapping pipe before pump 21 and a pressure tapping pipe after pump 22,

the main pipe is connected between the hot section 10 and the cold section 30 of the reactor coolant system loop, a first isolation valve 001, a circulating pump 002, a heat exchanger 004 and a second isolation valve 005 are sequentially arranged on the main pipe along the coolant flowing direction from the hot section 10 to the cold section 30,

the small flow pipe 20 is connected between a first communication port of the main pipe, which is a position between the first isolation valve 001 and the circulation pump 002, and a second communication port, which is a position between the heat exchanger 004 and the second isolation valve 005, and the small flow pipe 20 is provided with a self-operated differential pressure adjusting valve 006,

the circulation pump 002 divides the main pipe into a pump front section and a pump rear section,

the pressure tapping pipe 21 before the pump is provided between the front section of the main pipe and the self-operated differential pressure regulating valve 006, for introducing the pressure P1 of the coolant in the front section of the pump into the self-operated differential pressure regulating valve 006,

the post-pump pressure tapping pipe 22 is provided between the post-pump section of the main pipe and the self-operated differential pressure regulating valve 006, and is used to introduce the pressure P2 of the coolant in the post-pump section into the self-operated differential pressure regulating valve 006,

when the first isolation valve 001 is opened and the second isolation valve 005 is closed, and the pressure of the coolant in the cold section 30 of the reactor coolant system loop rises, the pressure difference P2-P1 is greater than the set value, so that the self-operated pressure difference regulating valve 006 is opened to realize the communication between the small flow pipe 20 and the main pipe,

when the first isolation valve 001 and the second isolation valve 005 are both opened, the pressure difference P2-P1 is smaller than the set value, so that the self-operated pressure difference regulating valve 006 is closed, and the small flow pipe 20 is disconnected from the main pipe.

The system is isolated from the reactor coolant system during power plant operating conditions by closing the first and second isolation valves 001,005. Before being put into a cooling reactor core, the system needs to be preheated so as to reduce the shortening of the service life of equipment caused by thermal shock.

By providing the pressure type differential pressure regulating valve 006 on the small flow pipe 20 and introducing the pre-pump pressure and the post-pump pressure of the circulating pump 002 on the waste heat discharge main pipe into the pressure type differential pressure regulating valve 006, the state of the pressure type differential pressure regulating valve 006 can be automatically adjusted according to the pump lift, thereby automatically controlling the on-off of the small flow pipe 20.

Under the preheating working condition, the first isolating valve 001 is opened, the second isolating valve 005 is closed, the pressure after the pump is high, the lift of the circulating pump 002 exceeds the set value of the pressure type differential pressure regulating valve 006, the pressure type differential pressure regulating valve 006 is automatically opened, the small flow pipe 20 is communicated, and the coolant is internally circulated between the waste heat discharging main pipe and the small flow pipe 20 through the circulating pump 002 until the circulating pump 002 heats the coolant in the internal circulation to the temperature requirement of the system communicated with a reactor coolant system; under the waste heat discharge operating mode, first isolation valve 001 and second isolation valve 005 all open, the pressure differential reduces around circulating pump 002 this moment, when circulating pump 002 lift reduces to the setting value that is less than pressure formula pressure differential governing valve 006, pressure formula pressure differential governing valve 006 self-closing, little flow pipe 20 is kept apart, coolant in reactor coolant system hot section 10 passes through circulating pump 002 and pumps into in heat exchanger 004 on waste heat discharge main line, send to in reactor coolant system's cold section 30 after the cooling, in order to discharge the waste heat in the reactor coolant system. Moreover, when the pressure of the cold section 30 of the reactor coolant system loop suddenly rises or the second isolating valve is closed, the resistance which needs to be overcome by the circulating pump 002 increases, the flow rate decreases, and the lift rises until the pressure exceeds the set value of the pressure type differential pressure regulating valve 006, the pressure type differential pressure regulating valve 006 is opened, the small flow pipe 20 is communicated, the circulating pump 002 is converted into the internal circulation of the system from the circulation of the reactor coolant system, and the circulating pump 002 cannot be locked or damaged, so that the safety state of the equipment and the system is maintained.

Therefore, the system realizes the automatic opening and closing of the small flow pipe 20 under different requirement working conditions on the premise of not needing additional instrument control logic configuration, so that the preheating function of the waste heat discharge system and the protection function of the circulating pump 002 can be realized, and the automatic isolation of the small flow pipe 20 during the execution of normal cooling can be realized. Therefore, the system has the advantages of simple structure and high reliability, and simultaneously has direct improvement on the cooling capacity of the system, thereby having remarkable economic benefit; in addition, the safety of the circulating pump is also ensured.

In addition, due to the arrangement of the system, the shutdown refueling time is shortened, the cooling capacity of the system is improved, the operation method is safe, the arrangement is simple, and the system has excellent economical efficiency and operation capacity.

In this embodiment, in order to ensure the accuracy of the pressure before the pump, the pressure sampling pipe 21 before the pump is disposed between the first communication port of the main pipe and the self-operated differential pressure regulating valve 006.

In this embodiment, the post-pump pressure tapping pipe 22 is provided between the third communication port of the main pipe and the self-operated differential pressure regulating valve 006, and the third communication port is located between the circulation pump 002 and the heat exchanger 004.

In this embodiment, the main pipe is further provided with a check valve 003, and the check valve 003 is a position between the circulation pump 002 and the heat exchanger 004.

As shown in fig. 2, in the present embodiment, the self-operated differential pressure regulating valve 006 includes a main valve 1, a pilot valve 2 and a valve stem 3,

the main valve 1 is provided with a main valve cavity, a valve seat 4 is arranged in the main valve cavity, the main valve cavity is divided into a liquid inlet cavity 11 and a liquid outlet cavity 12 by the valve seat, the liquid inlet cavity 11 is provided with a liquid inlet which is connected with the front section of the main pipe pump, the liquid outlet cavity 12 is provided with a liquid outlet which is connected with the rear section of the main pipe pump, a valve port which is communicated with the liquid inlet cavity and the liquid outlet cavity is arranged on the valve seat 4,

the pilot valve 2 is provided with a membrane cavity, a membrane 5 is arranged in the membrane cavity, the membrane cavity is divided into an upper membrane cavity 201 and a lower membrane cavity 202 by the membrane 5, a pressure tapping pipe 21 before the pump is communicated with the lower membrane cavity 202, a pressure tapping pipe 22 after the pump is communicated with the upper membrane cavity 201,

one end of the valve rod 3 is connected with the diaphragm 5 through a spring 6, the other end of the valve rod 3 is provided with a valve core 31 matched with the valve port of the valve seat, the set value is the elastic force of the spring 6,

when the pressure difference Δ P between the upper and lower ends of the diaphragm 5 is smaller than the elastic force of the spring 6, the valve core 31 closes the valve port to realize the automatic closing of the self-operated pressure difference regulating valve 006,

when the differential pressure Δ P is smaller than the elastic force of the spring 6, the valve rod 3 moves upward to drive the valve core 31 to open the valve port, so as to realize the automatic opening of the self-operated differential pressure regulating valve 006.

In particular, the pressure P taken upstream of the membrane 5₂And downstream pressure taking pressure P₁The acting force is input into the membrane chamber through a pipeline and acts on the membrane 5, the generated acting force is balanced with the reacting force of the spring 6, the relative position of the valve core 31 and the valve seat 4 is determined, and the closing of the valve is controlled. When P is present₂、P₁When the differential pressure increases, the force of the diaphragm 5 becomes larger than the reaction force of the spring 6, and the valve element 31 opens to the position of the valve seat 4. When P is present₂、P₁When the pressure difference is reduced, the diaphragm 5The upward force is smaller than the reaction force of the spring 6, and the valve body 31 is closed to the position of the valve seat 4.

Specifically, the method comprises the following steps:

during the power plant power operation, the first isolation valve 001 and the second isolation valve 005 are closed, the system and the reactor coolant system are isolated from the system and are in a standby state, the circulating pump 002 stops running, and the self-operated differential pressure regulating valve 006 on the small flow pipe 20 is in a closed state;

during shutdown, when the temperature of a reactor coolant system of a power plant is reduced to 180 ℃, the system reaches an intervention point, and the system starts to preheat. The first isolation valve 001 is opened, the second isolation valve 005 is still in a closed state, the inlet pipeline (the front section of the main pipe) of the system is communicated with the reactor coolant system, the system is boosted to 2.5-3.0MPa, and the circulating pump 002 is started. Because the return pipeline (the rear section of the main pipe) is closed, the resistance which needs to be overcome by the circulating pump 001 is large, the lift exceeds the set value of the self-operated differential pressure regulating valve 006, the small flow pipe 20 is communicated, and the circulating pump 002 performs internal circulation through the small flow pipe 20 until the temperature in the system is heated to the temperature difference with the reactor coolant system less than 60 ℃, so that the condition requirement that the system is communicated with the reactor coolant system is met.

Later, the second isolating valve 005 is opened, the inlet and outlet pipelines of the system are communicated with the reactor coolant system, the circulating pump 002 starts to circularly cool the reactor coolant, the resistance is reduced, and the flow of the circulating pump 002 is increased to 850m³And h, the lift becomes lower and is smaller than the set value of the self-operated differential pressure regulating valve 006, the self-operated differential pressure regulating valve 006 is closed, the small flow pipe 20 is isolated, and the flow passing through the circulating pump 002 is the pure cooling flow.

When the system is cooling a reactor, under some accident conditions, such as sudden rise of the pipeline pressure of the cold section 30 of the loop of the reactor coolant system, or the closing of the second isolation valve 005, the resistance to be overcome by the circulating pump 002 is increased, the flow is reduced, the lift rises until the constant value of the self-operated differential pressure regulating valve 006 is exceeded, the self-operated differential pressure regulating valve 006 is opened, the small flow pipe 20 is communicated, the circulating pump 002 is converted into the internal circulation of the system from the circulation of the reactor coolant system, the circulating pump 002 cannot be blocked or damaged, and the safety state of equipment and the system is maintained.

Example 2:

the present example provides a method of removing excess heat from a reactor coolant system using the system of example 1, comprising the steps of:

the first isolation valve 001 is opened, the second isolation valve 005 is closed to communicate the main pipe with the small flow pipe 20, the circulation pump 002 is started, the coolant in the circulation formed by the small flow pipe 20 and the main pipe is heated to a set value by the power of the circulation pump 002,

the second isolation valve 005 is opened to disconnect the main pipe from the small flow pipe 20 and circulate the reactor coolant system, and the coolant in the hot section 10 of the reactor coolant system loop is pumped into the heat exchanger 004 by the power of the circulating pump 002 to be cooled and then sent to the hot section 10 of the reactor coolant system loop.

Taking a waste heat removal system used in a power plant as an example, a head characteristic curve of the system is shown in fig. 3, and the differential pressure of the self-operated differential pressure regulating valve 006 in the system is set to 83m (corresponding to a pump flow rate of 400 m)³H), i.e. the pump flow is 400m³When the lift is more than/h (corresponding to the lift is less than 83m), the self-operated differential pressure regulating valve 006 is closed, and the system enters a waste heat discharging working condition; the pump flow is 400m³When the lift is less than/h (corresponding to the lift is greater than 83m), the self-operated differential pressure regulating valve 006 is opened, and the system enters a preheating working condition.

Example 3:

the embodiment provides a nuclear power system which comprises a reactor coolant system and a waste heat removal system in embodiment 1.

It will be understood that the above embodiments are merely exemplary embodiments taken to illustrate the principles of the present invention, which is not limited thereto. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.