WO2025256296A1 - Secondary circuit startup and shutdown system - Google Patents

Abstract

Provided in the present application is a secondary circuit startup and shutdown system, comprising: a steam generator; a deaerator, wherein a first port of the deaerator is connected to an output end of the steam generator, and a second port of the deaerator is connected to an input end of the steam generator; a condenser, wherein a first port of the condenser is connected to a third port of the deaerator; a water-side return pipeline, which is connected between a fourth port of the deaerator and a second port of the condenser; and a steam-side return pipeline, which is connected between a fifth port of the deaerator and a third port of the condenser. The secondary circuit startup and shutdown system provided in the present application can receive a low-parameter working medium generated by the steam generator in a secondary circuit startup and shutdown stage and can achieve full utilization of recovered heat thereof.

Description

Dual-circuit start-stop system Technical Field

This application relates to the field of nuclear power technology, and in particular to a dual-loop start-stop system.

Background Technology

The main function of the secondary loop system is to supply the saturated steam generated by the steam generator to the steam turbine to generate electricity. After the steam has done its work, it is condensed into water in the condenser. The condensate is then deoxygenated by the deaerator before being fed back into the steam generator.

During the start-up and shutdown phase of the secondary loop, due to the low power output, the working fluid at the steam generator outlet is in a state of water and steam-water mixture. These low-parameter working fluids cannot be directly introduced into the steam turbine. Current secondary loop start-up and shutdown systems often directly introduce this low-parameter working fluid to the condenser for cooling, resulting in low thermal efficiency and economic benefits.

Summary of the Invention

This application proposes a dual-loop start-stop system that can receive the low-parameter working fluid generated by the steam generator during the dual-loop start-stop phase and fully utilize its regenerative properties.

A two-loop start-stop system according to an embodiment of this application includes:

Steam generator;

The deaerator has its first port connected to the output of the steam generator and its second port connected to the input of the steam generator.

The condenser has its first port connected to the third port of the deaerator.

The water-side return pipeline is connected between the fourth port of the deaerator and the second port of the condenser.

The steam-side return line is connected between the fifth port of the deaerator and the third port of the condenser.

When the working fluid at the outlet of the steam generator is a mixture of water and steam, the first port of the deaerator is connected to the output end of the steam generator, and the water-side return pipeline and the steam-side return pipeline are connected.

According to some embodiments of this application, the dual-circuit start-stop system further includes:

Steam pipeline, the steam pipeline connects the output end of the steam generator and the fourth port of the condenser, and a steam turbine is installed on the steam pipeline;

In the case where the working fluid at the outlet of the steam generator is a mixture of water and steam, the steam pipeline is interrupted.

When the working medium at the outlet of the steam generator is in a steam state, the water-side return pipeline and the steam-side return pipeline between the first port of the deaerator and the output end of the steam generator are interrupted, while the steam pipeline is connected.

According to some embodiments of this application, the steam pipeline includes:

The main steam pipeline connects the output end of the steam generator and the fourth port of the condenser, and a steam turbine is installed on the main steam pipeline.

The steam bypass line connects the output of the steam generator to the fourth port of the condenser and the sixth port of the deaerator, respectively.

Among them, when the working fluid at the outlet of the steam generator is in a steam state and the steam temperature has not reached the first condition, the main steam pipeline is interrupted and the steam bypass pipeline is opened.

When the working medium at the outlet of the steam generator is in a steam state and the steam temperature reaches the first condition, the main steam pipeline is opened and the steam bypass pipeline is interrupted.

According to some embodiments of this application, the steam bypass line includes:

The first regulating valve is located between the output end of the steam generator and the fourth port of the condenser;

The second regulating valve is located between the output end of the steam generator and the sixth port of the deaerator.

According to some embodiments of this application, the dual-circuit start-stop system further includes:

The feedwater pump is connected between the second port of the deaerator and the input port of the steam generator;

The feedwater pump recirculation line is connected between the seventh port of the deaerator and the output end of the feedwater pump. The feedwater pump recirculation line is used to return at least a portion of the water output by the feedwater pump to the deaerator.

According to some embodiments of this application, the dual-circuit start-stop system further includes:

The feedwater regulating component is connected between the output end of the feedwater pump and the input end of the steam generator. The feedwater regulating component is used to regulate the water flow rate at the input end of the steam generator.

According to some embodiments of this application, the water supply regulating assembly includes:

The third regulating valve is connected to the pipeline between the output end of the feedwater pump and the input end of the steam generator;

The fourth regulating valve is located on the pipeline and is connected in parallel with the third regulating valve.

According to some embodiments of this application, before the steam generator is started and the output steam temperature reaches the first condition, the third regulating valve is closed and the fourth regulating valve is opened; after the steam generator is started and the output steam temperature reaches the first condition, the third regulating valve is opened and the fourth regulating valve is closed.

According to some embodiments of this application, the dual-circuit start-stop system further includes:

Condensate feedwater pump, which is connected between the first port of the condenser and the third port of the deaerator;

The condensate pump recirculation line is connected between the fifth port of the condenser and the output end of the condensate pump. The condensate pump recirculation line is used to return at least a portion of the water output by the condensate pump to the condenser.

According to some embodiments of this application, the dual-circuit start-stop system further includes:

The fine treatment device is connected between the first port of the condenser and the third port of the deaerator. The fine treatment device is used to purify the water.

In this embodiment, when the working fluid at the steam generator outlet is a mixture of water and steam, the first port of the deaerator is connected to the output end of the steam generator via a pipeline, and the second port of the deaerator is connected to the input end of the steam generator via a pipeline. Simultaneously, water-side return pipelines and steam-side return pipelines are added between the deaerator and the condenser. Thus, the low-parameter working fluid that cannot directly enter the turbine during the secondary loop start-up and shutdown phases enters the deaerator, and its carried heat is recovered and utilized, improving thermal efficiency and economy. The return pipeline between the deaerator and the condenser maintains system thermal balance, avoiding large fluctuations in the thermal parameters of the secondary loop system caused by the instability of the working fluid flow at the steam generator outlet, achieving a smooth water-steam transition during start-up and shutdown. Through the deaerator return process and control, diversified pressure control of the deaerator is achieved, ensuring that the pressure and liquid level within the deaerator are in a normal state, guaranteeing the normal operation of the deaerator, improving its working efficiency, and consequently enhancing the start-up and shutdown control effect of the nuclear reactor. In addition, this application reduces the number of equipment and pipelines, meets the requirements of compact layout, and reduces process costs.

Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing this application.

Attached Figure Description

The above and/or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

Figure 1 is a schematic diagram of the structure of a two-circuit start-stop system according to one embodiment of this application;

Figure 2 is a schematic diagram of the structure of a two-circuit start-stop system according to another embodiment of this application;

Figure 3 is a schematic diagram of the structure of the two-loop start-stop system of another embodiment of this application when the outlet working fluid of the steam generator is in the state of water and steam-water mixture;

Figure 4 is a schematic diagram of the structure of a two-loop start-stop system according to another embodiment of this application, when the working fluid at the outlet of the steam generator is in a steam state.

Figure label:
1. Steam generator; 2. Deaerator; 3. Condenser; 4. Steam turbine; 5. Feedwater pump; 6. Condensate feedwater pump; 7. Fine treatment unit.
First regulating valve 8, second regulating valve 9, third regulating valve 10, fourth regulating valve 11, main steam isolation valve 12, condensate regulating valve 13, turbine inlet steam isolation valve 14, containment isolation valve 15, condensate feedwater regulating valve 16, water-side return regulating valve 17, steam-side return regulating valve 18, feedwater pump recirculation flow regulating valve 19, condensate feedwater pump recirculation flow regulating valve 20.

Detailed Implementation

The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

In the description of this application, the use of terms such as "first," "second," etc., is for the purpose of distinguishing technical features only and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or the order of the technical features indicated.

In the description of this application, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

In the description of this application, it should be noted that, unless otherwise explicitly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

The technical solution of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are some embodiments of this application, not all embodiments.

To better describe the secondary loop start-up and shutdown system of this application embodiment, a brief introduction to the secondary loop start-up and shutdown process is provided here. During reactor start-up and shutdown, the working fluid at the outlet of steam generator 1 undergoes the operating stages of a water-solid state, a steam-water mixture, saturated steam, and superheated steam. During the reactor start-up and other upward operating stages, the unit progresses from the water-solid state operating stage to the steam production stage and then to the superheated steam operating stage. During the shutdown and other downward operating stages, the unit undergoes the reverse process of the upward process, progressing from the superheated steam operating stage to the steam production stage and then to the water-solid state operating stage.

Based on the above description, the embodiments of this application will be further described below with reference to the accompanying drawings. Referring to Figures 1 to 4, Figure 1 is a structural schematic diagram of a two-loop start-stop system according to one embodiment of this application; Figure 2 is a structural schematic diagram of a two-loop start-stop system according to another embodiment of this application; Figure 3 is a structural schematic diagram of a two-loop start-stop system according to another embodiment of this application when the working fluid at the outlet of the steam generator is in a state of water and steam-water mixture; and Figure 4 is a structural schematic diagram of a two-loop start-stop system according to another embodiment of this application when the working fluid at the outlet of the steam generator is in a state of steam.

As shown in Figure 1, this application embodiment proposes a two-loop start-stop system, which includes:

Steam generator 1;

Deaerator 2, the first port of deaerator 2 is connected to the output end of steam generator 1, and the second port of deaerator 2 is connected to the input end of steam generator 1;

Condenser 3, the first port of condenser 3 is connected to the third port of deaerator 2;

The water-side return pipeline is connected between the fourth port of deaerator 2 and the second port of condenser 3.

The steam-side return line is connected between the fifth port of deaerator 2 and the third port of condenser 3.

When the working fluid at the outlet of the steam generator 1 is a mixture of water and steam, the first port of the deaerator 2 is connected to the output end of the steam generator 1, and the water-side return pipeline and the steam-side return pipeline are connected.

In this embodiment, when the working fluid at the outlet of steam generator 1 is a mixture of water and steam, the first port of deaerator 2 is connected to the output of steam generator 1 via a pipeline, and the second port of deaerator 2 is connected to the input of steam generator 1 via a pipeline. Simultaneously, water-side return pipelines and steam-side return pipelines are added between deaerator 2 and condenser 3. Thus, the low-parameter working fluid that cannot directly enter turbine 4 during the secondary loop start-up and shutdown phases enters deaerator 2, and its carried heat is recovered and utilized, improving thermal efficiency and economy. The return pipeline between deaerator 2 and condenser 3 maintains system thermal balance, avoiding large fluctuations in the thermal parameters of the secondary loop system caused by the instability of the working fluid flow at the outlet of steam generator 1, achieving a smooth water-steam transition during start-up and shutdown. Through the deaerator 2 return process and control, diversified pressure control of deaerator 2 is achieved, ensuring that the pressure and liquid level within deaerator 2 are in a normal state, guaranteeing the normal operation of deaerator 2, improving its working efficiency, and thus enhancing the start-up and shutdown control effect of the nuclear reactor. In addition, this application reduces the number of equipment and pipelines, meets the requirements of compact layout, and reduces process costs.

The steam generator 1 described above can be a mechanical device that uses the thermal energy of fuel or other energy sources to heat water into hot water or steam, and it can be a steam generator 1 with any circulation mode.

For example, the steam generator 1 mentioned above can be a direct-flow steam generator. This direct-flow steam generator adopts a compact design, which not only saves space but also facilitates installation and maintenance. This compact structure also makes the direct-flow steam generator more efficient and less energy-consuming, while reducing water consumption. This high efficiency and low energy consumption make the direct-flow steam generator excellent in terms of environmental protection. In addition, the direct-flow steam generator operates very quietly and does not generate excessive noise that could have adverse effects.

The steam generator 1 described above can be equipped with a main steam isolation valve 12 at its output end, which can be closed to stop the output when necessary.

The first port of the aforementioned deaerator 2 is connected to the output end of the steam generator 1. This can be achieved by connecting the first port of the deaerator 2 to the output end of the steam generator 1 via a pipeline. During low-power processes such as reactor start-up and shutdown, the deaerator 2 can transport low-parameter working fluids such as water or steam-water mixtures from the outlet of the steam generator 1 to the deaerator 2, recovering and utilizing their heat to heat the condensate feedwater, and preventing low-parameter steam from entering the turbine 4.

A regulating valve assembly can be installed on the pipeline. This assembly can control the outlet pressure of steam generator 1 within a preset range when the working fluid at the outlet of steam generator 1 is a mixture of water and steam. Specifically, the outlet pressure of steam generator 1 can be controlled between 6 MPa and 8 MPa. For example, the outlet pressure of steam generator 1 can be controlled at 6 MPa or 8 MPa, and more specifically, the outlet pressure of steam generator 1 can be maintained at 7 MPa.

The second port of the deaerator 2 is connected to the input end of the steam generator 1. Alternatively, the second port of the deaerator 2 can be connected to the input end of the steam generator 1 via a pipeline. A regulating valve assembly can be installed on the pipeline to regulate the water flow rate supplied by the deaerator 2 to the steam generator 1, so that the water flow rate meets the operating requirements of the steam generator 1.

The first port of the condenser 3 is connected to the third port of the deaerator 2. This connection can be achieved by a pipeline connecting the first port of the condenser 3 to the third port of the deaerator 2. A regulating valve assembly can be installed on the pipeline to regulate the flow rate of condensate feedwater entering the deaerator 2 from the condenser 3. This can control the liquid level in the deaerator 2, ensuring that the liquid level in the deaerator 2 is within the normal range and guaranteeing the normal operation of the deaerator 2.

The aforementioned steam-side return pipeline, when the working fluid at the outlet of steam generator 1 is a mixture of water and steam, is used to return at least a portion of the steam in deaerator 2 to condenser 3. A regulating valve assembly can be installed on this pipeline to adjust the steam flow rate entering condenser 3, thereby controlling the pressure of deaerator 2 and maintaining it within its normal operating range, ensuring the normal operation of deaerator 2.

The aforementioned water-side return pipeline is used to return at least a portion of the water in deaerator 2 to condenser 3 when the working fluid at the outlet of steam generator 1 is a mixture of water and steam. A regulating valve assembly can be installed on this pipeline to adjust the flow rate of condensate returning from deaerator 2 to condenser 3, thereby controlling the liquid level in deaerator 2 and ensuring it remains within the normal range for normal operation.

For example, the first port of deaerator 2 is connected to the output end of steam generator 1 via a condensate bypass pipeline. A condensate regulating valve 13 is installed on the condensate bypass pipeline to control the outlet pressure of steam generator 1 within the aforementioned preset range. Specifically, the outlet pressure of steam generator 1 can be maintained at 7 MPa. The second port of deaerator 2 is connected to the input end of steam generator 1 via a feedwater pipeline. A feedwater regulating valve is installed on the feedwater pipeline to control the feedwater flow rate of steam generator 1. The first port of condenser 3 is connected to the third port of deaerator 2 via a condensate feedwater pipeline. A condensate feedwater regulating valve 16 is installed on the condensate feedwater pipeline to control the liquid level of deaerator 2. A steam-side return regulating valve 18 is installed on the steam-side return pipeline to control the pressure of deaerator 2. A water-side return regulating valve 17 is installed on the water-side return pipeline to control the liquid level of deaerator 2.

In the case where the working fluid at the outlet of the steam generator 1 is a mixture of water and steam, the working fluid at the outlet can be either water or a mixture of steam and water.

For example, when steam generator 1 is in the water-solid operation stage, its outlet working medium is water, the power step is approximately 0%FP to 2.5%FP, and the feedwater flow rate increases from 1%FF to 11.5%FF. When steam generator 1 is in the steam production stage, its outlet working medium is a mixture of water and steam, the power step is approximately 2.5%FP to 7.5%FP, and the feedwater flow rate is 11.5%FF. Here, 100%FP represents full power, and 100%FF represents the feedwater flow rate corresponding to full power.

When the working fluid at the outlet of steam generator 1 is in a state of water and steam-water mixture, the drain bypass line, steam-side return line and water-side return line are connected, the drain regulating valve 13 is opened and the outlet pressure of steam generator 1 is maintained within the preset range. Specifically, the outlet pressure of steam generator 1 can be maintained at 7 MPa.a, the steam-side return regulating valve 18 is opened and the pressure of deaerator 2 is controlled, and the water-side return regulating valve 17 is opened and the liquid level of deaerator 2 is controlled.

As shown in Figure 2, in some embodiments, the two-loop start-stop system may further include:

A steam pipeline connects the output end of the steam generator 1 to the fourth port of the condenser 3, and a steam turbine 4 is installed on the steam pipeline.

In the case where the working fluid at the outlet of steam generator 1 is a mixture of water and steam, the steam pipeline is interrupted.

When the working medium at the outlet of steam generator 1 is in a steam state, the first port of deaerator 2 is disconnected from the output end of steam generator 1, the water-side return pipeline and the steam-side return pipeline are interrupted, and the steam pipeline is connected.

In this embodiment, the secondary loop start-stop system may further include a steam pipeline. When the working medium at the outlet of the steam generator 1 is in a steam state, there is no need for water-steam separation. The steam pipeline is simply connected from the output end of the steam generator 1 to the condenser 3. Simultaneously, a steam turbine 4 is installed on the steam pipeline, and the steam in the pipeline enables the steam turbine 4 to perform work. By setting up corresponding pipelines for different working medium states at the outlet of the steam generator 1, better operating conditions and higher efficiency can be achieved in each state.

The above-mentioned situation, where the working medium at the outlet of steam generator 1 is in a steam state, can be a situation where the working medium at the outlet of steam generator 1 is in a superheated steam state.

For example, when steam generator 1 is in the superheated steam operation stage, its outlet working medium is superheated steam, the power step is about 7.5%FP to 10%FP, and the feedwater flow rate decreases from 11.5%FF to 10%FF.

A regulating valve assembly can be installed on the aforementioned steam pipeline to regulate the flow or isolation of the steam pipeline.

For example, when the drain regulating valve 13 detects that the outlet working fluid of the steam generator 1 is in the state of superheated steam, it closes after a few seconds, the drain line is no longer open, the steam-side return regulating valve 18 and the water-side return regulating valve 17 then close, the steam-side return line and the water-side return line are no longer open, the regulating valve assembly on the steam line controls the steam line to open, and the regulating valve assembly controls the outlet pressure of the steam generator 1 to be within the preset range mentioned above. Specifically, it can be to maintain the outlet pressure of the steam generator 1 at 7 MPa.a. At this time, the superheated steam working fluid at the outlet of the steam generator 1 flows through the steam line.

In some implementations, even when the outlet working fluid of the steam generator 1 is in a steam state, the first port of the deaerator 2 and the output port of the steam generator 1, as well as the water-side return line and the steam-side return line, can be connected.

As shown in Figure 2, in some embodiments, the steam pipeline may include:

The main steam pipeline connects the output end of the steam generator 1 and the fourth port of the condenser 3, and a steam turbine 4 is installed on the main steam pipeline.

The steam bypass line connects the output of the steam generator 1 to the fourth port of the condenser 3 and the sixth port of the deaerator 2, respectively.

Among them, when the working fluid at the outlet of steam generator 1 is in a steam state and the steam temperature has not reached the first condition, the main steam pipeline is interrupted and the steam bypass pipeline is opened.

When the working medium at the outlet of steam generator 1 is in a steam state and the steam temperature reaches the first condition, the main steam pipeline is opened and the steam bypass pipeline is interrupted.

In this embodiment, the steam pipeline may include a main steam pipeline and a steam bypass pipeline. When the working fluid at the outlet of the steam generator 1 is in a steam state and the steam temperature has not reached the first condition, the working fluid at the outlet of the steam generator 1 flows through the steam bypass pipeline and waits for the steam temperature to rise further. Once the steam temperature reaches the first condition, the steam bypass pipeline can be closed, allowing the working fluid at the outlet of the steam generator 1 to be transported through the main steam pipeline. The added steam bypass pipeline can handle changes in unit load by transporting excess steam to the condenser 3, removing heat, thereby matching the reactor power with the generating power of the turbine 4 units and maintaining the outlet pressure of the steam generator 1. In addition, a pipeline is configured to connect from the main steam pipeline to the deaerator 2, and the pipeline is equipped with a regulating valve to introduce fresh steam into the deaerator 2 during reactor start-up and shutdown to heat the condensate feedwater.

A regulating valve assembly can be installed on the main steam pipeline. This assembly allows for the connection or isolation of the main steam pipeline, as well as the regulation of the steam flow rate. The main steam pipeline can also transport the secondary working fluid, heated by steam generator 1, to other downstream conventional island systems and equipment.

For example, a steam inlet isolation valve 14 can be installed before the inlet of the steam turbine 4. When the working medium at the outlet of the steam generator 1 is in a steam state and the steam temperature has not reached the first condition, the steam inlet isolation valve 14 is closed. When the working medium at the outlet of the steam generator 1 is in a steam state and the steam temperature reaches the first condition, the steam inlet isolation valve 14 is opened. The steam inlet isolation valve 14 controls the outlet pressure of the steam generator 1 to be within the preset range mentioned above. Specifically, it can maintain the outlet pressure of the steam generator 1 at 7 MPa.a.

A regulating valve assembly can be installed on the aforementioned steam bypass pipeline. This regulating valve assembly can be used to connect or disconnect the steam bypass pipeline, and can also be used to regulate the steam flow rate of the main steam pipeline.

The first condition for the steam temperature to reach the specified temperature can be either a temperature sufficient to drive the steam turbine 4 to perform work, or a temperature sufficient to drive other downstream conventional island systems and equipment to perform work. The specific first condition can be determined based on the equipment conditions on the main steam pipeline.

As shown in Figure 2, in some embodiments, the steam bypass line may include:

The first regulating valve 8 is located between the output end of the steam generator 1 and the fourth port of the condenser 3.

The second regulating valve 9 is located between the output end of the steam generator 1 and the sixth port of the deaerator 2.

In this embodiment, the first regulating valve 8 and the second regulating valve 9 can realize the opening and closing of the steam bypass pipeline, and play a regulating and controlling role in the steam bypass pipeline.

The first regulating valve 8 is used to control the outlet pressure of the steam generator 1 within the preset range, specifically, to maintain the outlet pressure of the steam generator 1 at 7 MPa. The second regulating valve 9 can be installed on the steam bypass pipeline near the sixth port of the deaerator 2. The second regulating valve 9 can control the pressure of the deaerator 2 to a certain extent, maintain the pressure of the deaerator 2 within the normal operating range, and ensure the normal operation of the deaerator 2.

The first regulating valve 8 and the second regulating valve 9 can both be opened when the working medium at the outlet of the steam generator 1 is in a steam state and the steam temperature has not reached the first condition, and both can be closed when the working medium at the outlet of the steam generator 1 is in a steam state and the steam temperature reaches the first condition. Alternatively, the first regulating valve 8 and the second regulating valve 9 can be controlled separately according to the actual situation, and the two can perform different operations, such as opening or closing a single valve.

For example, when the drain valve 13 detects that the outlet working medium of the steam generator 1 is in a steam state, after a few seconds, the drain valve 13, the steam-side return valve 18, and the water-side return valve 17 close. The first regulating valve 8 opens and controls the outlet pressure of the steam generator 1 to be within the preset range. Specifically, it can maintain the outlet pressure of the steam generator 1 at 7 MPa.a. The second regulating valve 9 opens and controls the pressure of the deaerator 2. The steam bypass pipeline is connected, the regulating valve assembly on the main steam pipeline closes, and the main steam pipeline is interrupted. When the steam temperature at the outlet of the steam generator 1 further increases and reaches the first condition, the first regulating valve 8 and the second regulating valve 9 close, the steam bypass pipeline is interrupted, the regulating valve assembly on the main steam pipeline opens and controls the outlet pressure of the steam generator 1 to be within the preset range. Specifically, it can maintain the outlet pressure of the steam generator 1 at 7 MPa.a, the main steam pipeline is connected, and the steam drives the turbine 4 on the main steam pipeline to work.

In some implementations, a desuperheater and pressure reducer can be installed on the steam bypass line to preheat and depressurize the steam entering the condenser 3 through the steam bypass line.

As shown in Figures 1 and 2, in some embodiments, the two-circuit start-stop system may further include:

Feed water pump 5 is connected between the second port of deaerator 2 and the input port of steam generator 1;

The feedwater pump recirculation line is connected between the seventh port of the deaerator 2 and the output end of the feedwater pump 5. The feedwater pump recirculation line is used to return at least a portion of the water output by the feedwater pump 5 to the deaerator 2.

In this embodiment, feedwater pump 5 pressurizes the feedwater in deaerator 2 and delivers it to steam generator 1, meeting the feedwater flow rate and head requirements of steam generator 1. Furthermore, to ensure the safe start-up and normal operation of feedwater pump 5, a minimum discharge flow rate is required. However, during reactor start-up and shutdown, since the feedwater flow rate required by steam generator 1 is lower than the minimum discharge flow rate of feedwater pump 5, the excess flow rate from the outlet of feedwater pump 5 can be delivered to deaerator 2 through the feedwater pump recirculation pipeline, ensuring the normal operation of feedwater pump 5.

A water pump recirculation flow regulating valve 19 can be installed on the aforementioned water pump recirculation pipeline to control the flow rate of the water pump recirculation pipeline, so as to meet the minimum discharge flow rate of the water pump 5 and ensure the safe start-up and normal operation of the water pump 5.

As shown in Figures 1 and 2, in some embodiments, the two-circuit start-stop system may further include:

The water supply regulating component is connected between the output end of the water supply pump 5 and the input end of the steam generator 1. The water supply regulating component is used to regulate the water flow rate at the input end of the steam generator 1.

In this embodiment, the required feedwater flow rate of the steam generator 1 varies greatly depending on the power stage of the reactor. The feedwater regulation component can ensure the accuracy of feedwater regulation and can adjust the feedwater flow rate to meet the requirements of the steam generator 1 at different power stages.

The aforementioned water supply regulating components can be multiple valves connected in series or multiple valves connected in parallel on the pipeline.

As shown in Figures 1 and 2, in some embodiments, the water supply regulating component may include:

The third regulating valve 10 is connected to the pipeline between the output end of the water supply pump 5 and the input end of the steam generator 1.

The fourth regulating valve 11 is installed on the pipeline and connected in parallel with the third regulating valve 10.

In this embodiment, two valves connected in parallel can meet the two different water supply regulation requirements under higher power and lower power stages, respectively, thereby achieving more precise water supply regulation and meeting the water supply regulation accuracy requirements.

The aforementioned fourth regulating valve 11 is installed on the pipeline and connected in parallel with the third regulating valve 10. The pipeline where the third regulating valve 10 is located can be a full-load pipeline, and the third regulating valve 10 is used for regulating the water supply flow under a higher power platform. The pipeline where the fourth regulating valve 11 is located can be a low-load pipeline, and the fourth regulating valve 11 is used for regulating the water supply flow under a lower power platform.

For example, the third regulating valve 10 is the main feedwater regulating valve, which is installed on the main feedwater pipeline and is used to regulate the feedwater flow rate under higher power conditions. For example, in the power operation mode, after the turbine 4 starts generating electricity, the feedwater flow rate of the steam generator 1 is regulated by this valve. The fourth regulating valve 11 is the bypass feedwater regulating valve, which is installed on the bypass feedwater pipeline. The bypass feedwater pipeline is connected in parallel with the main feedwater pipeline and is used to regulate the feedwater flow rate under lower power conditions. For example, in the early stage of the startup process before the turbine 4 is put into operation, the feedwater flow rate of the steam generator 1 is controlled by this valve.

In some implementations, to ensure the regulating performance of the water supply regulating component, the water supply pump 5 automatically adjusts its speed after receiving the pressure difference signal across the water supply regulating component, maintaining the pressure difference within a preset range. Specifically, the pressure difference across the water supply regulating component can be controlled to be maintained between 0.3 MPa and 0.4 MPa. For example, the pressure difference can be controlled to be maintained at 0.3 MPa or 0.4 MPa, and more specifically, it can be maintained at approximately 0.35 MPa.

Specifically, under higher power conditions, after receiving the pressure difference signal across the third regulating valve 10, the water pump 5 will automatically adjust its speed to maintain the pressure difference across the third regulating valve 10 within the aforementioned preset pressure difference range, specifically, approximately 0.35 MPa.a. Under lower power conditions, after receiving the pressure difference signal across the fourth regulating valve 11, the water pump 5 will automatically adjust its speed to maintain the pressure difference across the fourth regulating valve 11 within the aforementioned preset pressure difference range, specifically, approximately 0.35 MPa.a.

In some embodiments, before the steam generator 1 is started and the output steam temperature reaches the first condition, the third regulating valve 10 is closed and the fourth regulating valve 11 is opened; after the steam generator 1 is started and the output steam temperature reaches the first condition, the third regulating valve 10 is opened and the fourth regulating valve 11 is closed.

In this embodiment, the condition for selecting between the third regulating valve 10 and the fourth regulating valve 11 is that the steam generator 1 is started and the output steam temperature does not reach the first condition. This enables more precise water supply regulation and meets the water supply regulation accuracy requirements.

As shown in Figures 1 and 2, in some embodiments, the two-circuit start-stop system may further include:

Condensate pump 6 is connected between the first port of condenser 3 and the third port of deaerator 2.

The condensate pump recirculation line is connected between the fifth port of the condenser 3 and the output end of the condensate pump 6. The condensate pump recirculation line is used to return at least a portion of the water output by the condensate pump 6 to the condenser 3.

In this embodiment, the condensate pump 6 pressurizes the condensate in the condenser 3 and delivers it to the deaerator 2 to meet the makeup water requirements of the deaerator 2. Furthermore, to ensure the safe start-up and normal operation of the condensate pump 6, a minimum discharge flow rate is required. However, during reactor start-up and shutdown, since the feedwater flow rate required by the deaerator 2 is lower than the minimum discharge flow rate of the condensate pump 6, the excess flow rate from the outlet of the condensate pump 6 can be delivered to the condenser 3 through the condensate pump recirculation pipeline, ensuring the normal operation of the condensate pump 6.

A condensate pump recirculation flow regulating valve 20 can be installed on the aforementioned condensate pump recirculation pipeline to control the flow rate of the condensate pump recirculation pipeline, so as to meet the minimum discharge flow rate of the condensate pump 6 and ensure the safe start-up and normal operation of the condensate pump 6.

The aforementioned condensate pump 6 is connected between the first port of the condenser 3 and the third port of the deaerator 2. The condensate pump 6 can be connected to the first port of the condenser 3 and the third port of the deaerator 2 via a pipeline. A regulating valve assembly can be installed on this pipeline to adjust the flow rate of condensate from the condenser 3 to the deaerator 2, thereby controlling the liquid level in the deaerator 2 and ensuring that the liquid level in the deaerator 2 remains within the normal range, thus guaranteeing the normal operation of the deaerator 2.

For example, the output end of the condensate pump 6 is connected to the third port of the deaerator 2 through the condensate pipeline, and a condensate regulating valve 16 is installed on the condensate pipeline to control the liquid level of the deaerator 2.

As shown in Figures 1 and 2, in some embodiments, the dual-loop start-stop system may also include a fine treatment device 7, which is connected between the first port of the condenser 3 and the third port of the deaerator 2. The fine treatment device 7 is used to purify the water.

In this embodiment, the fine treatment device 7 can be used to purify the water quality to meet the water quality requirements of the steam generator 1.

As shown in Figures 1 and 2, in some embodiments, the secondary loop start-stop system may also include a containment isolation valve 15. The containment isolation valve 15 is connected between the feedwater regulating assembly and the input end of the steam generator 1, and is mainly used to isolate the containment and limit the leakage of radioactive materials in the event of an accident.

To better describe the two-loop start-stop system of this application, it will be further described here by way of specific embodiments, please refer to Figures 2 to 4 for details.

In this specific embodiment, as shown in Figure 2, the output end of the steam generator 1 is connected to the first port of the deaerator 2 via a condensate bypass pipeline. A main steam isolation valve 12 is installed near the output end of the steam generator 1, and a condensate regulating valve 13 is installed on the condensate bypass pipeline. The output end of the steam generator 1 is also connected to the sixth port of the deaerator 2 and the fourth port of the condenser 3 via a bypass steam pipeline. A first regulating valve 8 is installed between the sixth port of the deaerator 2 and the fourth port of the condenser 3 on the bypass steam pipeline, and a second regulating valve 9 is installed near the sixth port of the deaerator 2. The output end of the steam generator 1 is also connected to the fourth port of the condenser 3 via a main steam pipeline. A steam turbine 4 is installed on the main steam pipeline, and a steam turbine inlet steam isolation valve 14 is installed before the steam turbine 4. The second port of the deaerator 2 is connected to the input end of the feedwater pump 5, and the output end of the feedwater pump 5 is connected to the input end of the steam generator 1 via a main feedwater pipeline. A third regulating valve 10 is installed on the main feedwater pipeline. The feedwater pipeline is connected in parallel with the main feedwater pipeline, and a fourth regulating valve 11 is installed on the bypass feedwater pipeline. A containment isolation valve 15 is also installed between the third regulating valve 10 and the input end of the steam generator 1. The output end of the feedwater pump 5 is also connected to the seventh port of the deaerator 2 through the feedwater pump recirculation pipeline. The first port of the condenser 3 is connected to the input end of the condensate feedwater pump 6, and the output end of the condensate feedwater pump 6 is connected to the third port of the deaerator 2 through the condensate feedwater pipeline. A fine treatment device 7 is installed on the condensate feedwater pipeline. A condensate regulating valve 16 is installed between the fine treatment unit 7 and the output end of the condensate pump 6. The output end of the condensate pump 6 is also connected to the fifth port of the condenser 3 through the condensate pump recirculation pipeline. The fourth port of the deaerator 2 is connected to the second port of the condenser 3 through the water-side return pipeline. A water-side return regulating valve 17 is installed on the water-side return pipeline. The fifth port of the deaerator 2 is connected to the third port of the condenser 3 through the steam-side return pipeline. A steam-side return regulating valve 18 is installed on the steam-side return pipeline.

When the working fluid at the outlet of steam generator 1 is in a state of water and steam-water mixture, as shown in Figure 3, the condensate bypass line, steam-side return line, and water-side return line are open, while the main steam line and steam bypass line are interrupted. Additionally, the main feedwater line is interrupted, while the bypass feedwater line is open. At this time, the condensate regulating valve 13 opens and automatically controls the outlet pressure of steam generator 1 to 7 MPa.a; the steam-side return regulating valve 18 opens and automatically controls the pressure of deaerator 2; the water-side return regulating valve 17 opens and automatically controls the liquid level of deaerator 2; and the condensate regulating valve 16 also automatically controls the liquid level of deaerator 2. The third regulating valve 10 closes, and the fourth regulating valve 11 opens and automatically regulates the feedwater flow rate of steam generator 1.

When the working medium at the outlet of steam generator 1 is in the steam state, when the condensate regulating valve 13 detects that it has entered the sub-state, after a few seconds, as shown in Figure 4, the condensate bypass line, steam-side return line and water-side return line are interrupted.

When the working fluid at the outlet of steam generator 1 is in a steam state and the steam temperature has not reached the first condition, the steam bypass pipeline is opened and the main steam pipeline is interrupted. At this time, the first regulating valve 8 opens and automatically controls the outlet pressure of steam generator 1 to 7 MPa.a, the second regulating valve 9 opens and automatically controls the pressure of deaerator 2, the condensate feedwater regulating valve 16 automatically controls the liquid level of deaerator 2, the turbine inlet steam isolation valve 14 closes, the third regulating valve 10 closes, and the fourth regulating valve 11 opens and automatically regulates the feedwater flow of steam generator 1.

When the working fluid at the outlet of steam generator 1 is in a steam state and the steam temperature reaches the first condition, the main steam pipeline is opened and the steam bypass pipeline is interrupted. At this time, the steam isolation valve 14 at the turbine inlet opens and automatically controls the outlet pressure of steam generator 1 to 7 MPa. The turbine 4 starts to connect to the grid, the condensate feedwater regulating valve 16 automatically controls the liquid level of deaerator 2, the first regulating valve 8 and the second regulating valve 9 are closed, the fourth regulating valve 11 is closed, the third regulating valve 10 opens and automatically regulates the feedwater flow of steam generator 1.

In this specific embodiment, when the working fluid at the outlet of steam generator 1 is a mixture of water and steam, the first port of deaerator 2 is connected to the output end of steam generator 1 via a pipeline, and the second port of deaerator 2 is connected to the input end of steam generator 1 via a pipeline. Simultaneously, water-side return pipelines and steam-side return pipelines are added between deaerator 2 and condenser 3. Thus, the low-parameter working fluid that cannot directly enter turbine 4 during the secondary loop start-up and shutdown phases enters deaerator 2, and its carried heat is recovered and utilized, improving thermal efficiency and economy. The return pipeline between deaerator 2 and condenser 3 maintains system thermal balance, avoiding large fluctuations in the thermal parameters of the secondary loop system caused by the instability of the working fluid flow at the outlet of steam generator 1, achieving a smooth water-steam transition during start-up and shutdown. Through the deaerator 2 return process and control, diversified pressure control of deaerator 2 is achieved, ensuring that the pressure and liquid level within deaerator 2 are in a normal state, guaranteeing the normal operation of deaerator 2, improving its working efficiency, and thus enhancing the start-up and shutdown control effect of the nuclear reactor.

Furthermore, this application, when the working fluid at the outlet of steam generator 1 is in different states, does not employ a start-up separator, start-up expansion tank, or steam-water separator. Instead, it achieves water-steam separation by switching different pipelines, avoiding the problem of low-parameter working fluid being unable to enter the superheater and turbine 4 under low power conditions. Simultaneously, it maintains the pressure and liquid level of deaerator 2 at normal levels, and keeps the outlet pressure of steam generator 1 at normal levels, ensuring stable system operation. Switching different pipelines for control instead of using a start-up separator, start-up expansion tank, or steam-water separator reduces the number of equipment and pipelines, simplifies the control method, lowers control requirements, meets the requirements for compact layout, and reduces process costs. This application also ensures the fine treatment requirements during reactor start-up and shutdown while meeting heat recovery requirements, satisfying the feedwater quality requirements of steam generator 1.

In the description of this specification, the references to terms such as "an embodiment," "some implementations," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

Although the embodiments of this application have been described in detail above with reference to the accompanying drawings, this application is not limited to the above embodiments. Those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application. The scope of this application is defined by the claims and their equivalents.

Claims (10)

A dual-circuit start-stop system, characterized in that it comprises: Steam generator; A deaerator, wherein the first port of the deaerator is connected to the output end of the steam generator, and the second port of the deaerator is connected to the input end of the steam generator; A condenser, wherein the first port of the condenser is connected to the third port of the deaerator; A water-side return pipeline is provided, which is connected between the fourth port of the deaerator and the second port of the condenser. A steam-side return line is provided, which connects the fifth port of the deaerator and the third port of the condenser. When the working fluid at the outlet of the steam generator is a mixture of water and steam, the first port of the deaerator is connected to the output end of the steam generator, and the water-side return pipeline and the steam-side return pipeline are connected. The system according to claim 1, characterized in that it further comprises: A steam pipeline is provided, which connects the output end of the steam generator and the fourth port of the condenser, and a steam turbine is installed on the steam pipeline. Where the working fluid at the outlet of the steam generator is in a state of water and steam-water mixture, the steam pipeline is interrupted; When the working fluid at the outlet of the steam generator is in a steam state, the connection between the first port of the deaerator and the output end of the steam generator, the water-side return pipeline and the steam-side return pipeline are interrupted, and the steam pipeline is connected. The system according to claim 2, wherein the steam pipeline comprises: The main steam pipeline connects the output end of the steam generator and the fourth port of the condenser, and a steam turbine is installed on the main steam pipeline. A steam bypass line connects the output of the steam generator to the fourth port of the condenser and the sixth port of the deaerator, respectively. Wherein, if the working fluid at the outlet of the steam generator is in a steam state and the steam temperature does not reach the first condition, the main steam pipeline is interrupted and the steam bypass pipeline is opened. When the working fluid at the outlet of the steam generator is in a steam state and the steam temperature reaches the first condition, the main steam pipeline is opened and the steam bypass pipeline is interrupted. The system according to claim 3, wherein the steam bypass line comprises: A first regulating valve is disposed between the output end of the steam generator and the fourth port of the condenser; The second regulating valve is located between the output end of the steam generator and the sixth port of the deaerator. The system according to claim 1, characterized in that it further comprises: A feedwater pump is connected between the second port of the deaerator and the input port of the steam generator; A feedwater pump recirculation line is provided, which is connected between the seventh port of the deaerator and the output end of the feedwater pump. The feedwater pump recirculation line is used to return at least a portion of the water output by the feedwater pump to the deaerator. The system according to claim 5, characterized in that it further comprises: A water supply regulating component is connected between the output end of the water supply pump and the input end of the steam generator, and the water supply regulating component is used to regulate the water flow rate at the input end of the steam generator. The system according to claim 6, wherein the water supply regulating component comprises: The third regulating valve is connected to the pipeline between the output end of the water supply pump and the input end of the steam generator; A fourth regulating valve is disposed on the pipeline and connected in parallel with the third regulating valve. According to claim 7, the system is characterized in that, before the steam generator is started and the output steam temperature reaches the first condition, the third regulating valve is closed and the fourth regulating valve is opened; after the steam generator is started and the output steam temperature reaches the first condition, the third regulating valve is opened and the fourth regulating valve is closed. The system according to claim 1, characterized in that it further comprises: A condensate feedwater pump is connected between the first port of the condenser and the third port of the deaerator; A condensate pump recirculation line is provided, which is connected between the fifth port of the condenser and the output end of the condensate pump. The condensate pump recirculation line is used to return at least a portion of the water output by the condensate pump to the condenser. The system according to claim 1, characterized in that it further comprises: A fine treatment device is connected between the first port of the condenser and the third port of the deaerator, and the fine treatment device is used to purify water quality.