A 600MW multi-module high temperature reactor start-up and shutdown system

Abstract

The present invention relates to the technical field of start-stop reactors, and in particular to a 600MW multi-module high temperature reactor start-stop system, including multiple steam generators, steam turbines, condensers and start-stop reactor expansion tanks, each of the steam generators is connected to the main steam main pipe through a main steam pipeline and then enters the steam turbine in two ways; a start-stop reactor pipeline is led out from the main steam pipeline of each steam generator and connected to the start-stop reactor expansion tank; each steam generator leads out a main steam bypass pipeline after leading out the start-stop reactor pipeline and is connected to the condenser, and each main steam bypass pipeline is provided with a bypass regulating valve. The present invention reduces the number of steam-water separators by setting a common start-stop reactor expansion tank; a start-stop reactor expansion tank is set on the side of the condenser, and due to its low pressure and thin wall thickness, no special cooling or insulation system is required, the system is simple, and the footprint is small; the main steam bypass valve is set for a single stack and led out from the main steam pipeline, and the control logic is relatively simple and clear.

Description

Technical Field

[0001] The present invention relates to the technical field of start-stop reactors, and in particular to a 600MW-class multi-module high-temperature reactor start-stop system. Background Art

[0002] The high-temperature gas-cooled reactor nuclear island adopts a modular design. The power generation capacity of each nuclear island module is 100MW. Therefore, the 200MW demonstration reactor has two reactor modules. In order to improve power generation efficiency and reduce the unit power unit cost, it is necessary to develop a 6-module 600MW high-temperature reactor technology.

[0003] Since the nuclear island steam generator starts at a constant pressure, during the startup or shutdown of the nuclear island, the main steam pressure at the steam generator outlet must be constant at the rated operating value, the flow rate is 36kg / s, and the medium temperature ranges from 150℃ to 571℃, undergoing subcooling, saturation, and overheating. In order to prevent water from entering the steam turbine during the startup and shutdown phases and to recover the working fluid as much as possible, a startup and shutdown system must be set up on the secondary circuit side of the conventional island, that is, a large main steam bypass is established to recover the medium during the subcooled water, saturated water, and saturated steam phases of startup or shutdown.

[0004] Each of the original 200MW demonstration reactors is equipped with an independent start-stop system (see the attached system diagram). Figure 1 ), including inlet regulating valve, start-stop reactor steam-water separator, exhaust and drain pipes and valves, steam-water separator cooling and insulation pipes, etc. The system is relatively complex.

[0005] If the 600MW demonstration reactor adopts the configuration of the original 200MW demonstration reactor with a single independent start-stop system, the six reactors need to be equipped with six or three start-stop steam-water separators. The main disadvantages are as follows:

[0006] (1) Six reactors require six sets of start-stop reactor steam-water separators, as well as related rapid cooling and insulation systems. The systems are complex, the project cost is high, and the area occupied is large.

[0007] (2) When a single reactor is operating normally, the corresponding steam-water separator needs to be kept warm and kept on standby. When the reactor is shut down, it needs to be cooled quickly to match the temperature at the start-up of the reactor. The operation process is relatively complicated.

[0008] (3) The main steam bypass valve is led out from the main steam main pipe and participates in the medium discharge and pressure control in the initial stage of starting and shutting down the reactor overheating. In addition to the original main steam discharge function under accident conditions, the main steam bypass valve has more operating conditions and is more complex to control. Summary of the invention

[0009] The present invention solves the problems in the related art that a 600MW demonstration reactor needs to be equipped with multiple steam-water separators, the system is complex, the project cost is high, the floor area is large, the operation process is complex, the main steam bypass valve has many working conditions, and the control is relatively complex. A 600MW multi-module high-temperature reactor start-stop system is proposed, and a common start-stop expansion tank is set to reduce the number of steam-water separators; a start-stop expansion tank is set next to the condenser, and due to its low pressure and thin wall thickness, a dedicated cooling or insulation system is not required, the system is simple, and the floor area is small; the bypass regulating valve is set for a single stack and is led out from the main steam pipeline, and the control logic is relatively simple and clear.

[0010] In order to solve the above technical problems, the present invention is achieved through the following technical solutions: a 600MW multi-module high-temperature reactor start-stop system, comprising a plurality of steam generators, a steam turbine, a condenser and a start-stop reactor expansion vessel, wherein each of the steam generators is connected to a main steam main pipe through a main steam pipeline and then enters the steam turbine in two ways; a start-stop reactor pipeline is led out from the main steam pipeline of each steam generator and connected to the start-stop reactor expansion vessel; after leading out the start-stop reactor pipeline, each steam generator leads out a main steam bypass pipeline and is connected to the condenser, and each of the main steam bypass pipelines is provided with a bypass regulating valve.

[0011] As a preferred solution, there are six steam generators, namely a first steam generator, a second steam generator, a third steam generator, a fourth steam generator, a fifth steam generator and a sixth steam generator.

[0012] As a preferred solution, each main steam pipeline between the start-stop stack pipeline and the main steam bypass pipeline is provided with a first isolation valve, and each main steam pipeline between the main steam bypass pipeline and the main steam main pipe is provided with a second isolation valve.

[0013] As a preferred solution, a third isolation valve and a main steam valve are provided on the two main steam main pipes.

[0014] As a preferred solution, each of the start-stop stack pipelines is provided with a fourth isolation valve and a start-stop stack regulating valve.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1) The start-stop reactor adopts a shared expansion vessel to reduce the complexity of the start-stop reactor system;

[0017] 2) The startup and shutdown of the reactor is more flexible, and it can withstand the startup and shutdown conditions of multiple reactors at one time without affecting each other;

[0018] 3) Since the pressure of the start-stop reactor expansion vessel is reduced, its wall thickness is reduced, and its adaptability to temperature changes is enhanced. There is no need for a dedicated cooling and insulation system, and the configuration and operation of the start-stop reactor system are simpler;

[0019] 4) A start-stop reactor expansion vessel is set up next to the condenser. Due to the low pressure and thin wall thickness, and the exhaust and drain pipes are connected to the condenser, there is no need for a dedicated cooling or insulation system. The system is simple and occupies a small area.

[0020] 5) The bypass regulating valve is set in a single stack, and the control of the bypass regulating valve is relatively clear and simple;

[0021] 6) The medium pipeline switching point is switched before the start-stop stack regulating valve, avoiding the layout problem of the pipeline after the valve;

[0022] 7) Eliminate the steam-water separator and directly use the steam generator outlet medium to flush, making the system simpler. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0024] In the figure:

[0025] 101. The first steam generator, 102. The second steam generator, 103. The third steam generator, 104. The fourth steam generator, 105. The fifth steam generator, 106. The sixth steam generator, 11. The main steam pipeline, 111. The first isolating valve, 112. The second isolating valve, 12. The main steam main pipe, 121. The third isolating valve, 122. The main steam valve, 13. The start-stop stack pipeline, 131. The fourth isolating valve, 132. The start-stop stack regulating valve, 14. The main steam bypass pipeline, 141. The bypass regulating valve, 2. The steam turbine, 3. The condenser, 4. The start-stop stack expansion vessel. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0028] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0029] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0030] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0031] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0032] like Figure 1As shown, a 600MW multi-module high-temperature reactor start-stop system includes multiple steam generators, a steam turbine 2, a condenser 3 and a start-stop reactor expansion vessel 4. Each steam generator is connected to a main steam main pipe 12 through a main steam pipeline 11 and then enters the steam turbine 2 in two ways; a start-stop reactor pipeline 13 is led out from the main steam pipeline 11 of each steam generator and connected to the start-stop reactor expansion vessel 4; after leading out the start-stop reactor pipeline 13, each steam generator leads out a main steam bypass pipeline 14 to be connected to the condenser 3, and each main steam bypass pipeline 14 is provided with a bypass regulating valve 141.

[0033] In one embodiment, there are six steam generators, namely a first steam generator 101 , a second steam generator 102 , a third steam generator 103 , a fourth steam generator 104 , a fifth steam generator 105 and a sixth steam generator 106 .

[0034] In one embodiment, a first isolation valve 111 is provided on each main steam pipeline 11 between the start-stop stack pipeline 13 and the main steam bypass pipeline 14 , and a second isolation valve 112 is provided on each main steam pipeline 11 between the main steam bypass pipeline 14 and the main steam main pipe 12 .

[0035] In one embodiment, a third isolation valve 121 and a main steam valve 122 are provided on the two main steam main pipes 12 .

[0036] In one embodiment, each start-stop stack pipeline 13 is provided with a fourth isolation valve 131 and a start-stop stack regulating valve 132 .

[0037] In the present invention, the start-stop reactor steam-water separator is eliminated, and the supercooled water, saturated water and saturated steam in the early stage of the startup phase enter the start-stop reactor expansion container 4 next to the condenser 3 through the start-stop reactor pipeline 13 led out from the main steam pipeline 11.

[0038] At the same time, in order to solve the vibration problem behind the inlet regulating valve pipeline of the start-stop stack expansion vessel 4 in the present invention, the start-stop stack regulating valve 132 should be arranged as close to the start-stop stack expansion vessel 4 as possible. Since the pressure after the valve is relatively low, the corresponding pipe diameter is relatively large. If a switching pipe is set in the pipeline after the valve, it is difficult to arrange. Therefore, the medium switching point is adjusted to before the start-stop stack regulating valve 132, and no switching pipe is set after the start-stop stack regulating valve 132.

[0039] During the startup and run-up process of the first stack, the steam-water separator is eliminated, and when the outlet medium temperature of the steam generator meets the run-up temperature requirement, it can be directly used to run the steam turbine 2, thereby further reducing the complexity of the system and simplifying the operation process and investment.

[0040] Since this project has 6 reactors, the start-up and shutdown conditions are relatively more complicated, and this description only explains and analyzes the main conditions. The startup conditions in the start-up and shutdown conditions mainly include: normal cold start in sequence, warm start with shutdown, and hot start without stopping. The shutdown conditions mainly include: accident shutdown and normal shutdown in sequence. The normal shutdown process is the reverse process of the startup process, and the warm and hot startup processes are basically similar to the cold start, except that the temperature of the steam medium during the start-up is different according to the temperature of the turbine 2. In the accident shutdown condition, the main function of the start-up and shutdown is to receive the medium after cooling from the feedwater steam generator, and the steam cooling function of the steam generator is moved to the auxiliary steam system. In summary, the present invention mainly analyzes the two startup conditions of the first normal start-up of the steam turbine 2 and the subsequent start-up of the reactor.

[0041] In summary, taking a 6-module high temperature reactor with a rated pressure of 13.9 MPa at the steam generator outlet as an example, the present invention is described in detail as follows. The system schematic diagram is shown in the attached Figure 1 :

[0042] (1) Startup condition 1 (first stack startup condition):

[0043] During the startup subcooling stage and saturation stage (the outlet pressure of the steam generator is 13.9 MPa(a), the outlet temperature of the steam generator is from 150°C to 336.1°C, the medium is water, and after saturation, the medium gradually changes from water to saturated steam, with a flow rate of 36 kg / s), the two third isolation valves 121 from the main steam pipeline 11 at the steam generator outlet to the main steam main pipe 12 are in a closed state, and the medium flows from the steam generator outlet along the main steam pipeline 11 through the corresponding fourth isolation valve 131 and the start-stop stack regulating valve 132 and enters the start-stop stack expansion vessel 4.

[0044] In the overheating stage 1 (the outlet pressure of the steam generator is 13.9 MPa(a), the outlet temperature of the steam generator is 336.1°C to 355°C, the medium gradually changes from saturated steam to superheated steam, and the flow rate is 36 kg / s), the two third isolation valves 121 from the main steam pipeline 11 at the steam generator outlet to the main steam main pipe 12 are in a closed state, and the medium flows from the steam generator outlet along the main steam pipeline 11 through the corresponding fourth isolation valve 131 and the start-stop stack regulating valve 132 and enters the start-stop stack expansion vessel 4.

[0045] In the second overheating stage (the outlet pressure of the steam generator is 13.9 MPa(a), the outlet temperature of the steam generator remains at 355°C, and the medium is superheated steam), the first isolation valve 111 on the corresponding main steam pipeline 11 is gradually opened, so that a part of the main steam enters the condenser 3 along the main steam pipeline 11 through the bypass regulating valve 141, and the other part still enters the start-stop stack expansion vessel 4 from the start-stop stack regulating valve 132. In this process, the bypass regulating valve 141 and the start-stop stack regulating valve 132 jointly adjust the main steam pressure at the steam generator outlet to 13.9 MPa(a), and at the same time, the opening of the start-stop stack regulating valve 132 gradually decreases, and the opening of the bypass regulating valve 141 gradually increases until the start-stop stack regulating valve 132 is closed, and the main steam pressure at the steam generator outlet is controlled by the bypass regulating valve 141 alone to be 13.9 MPa(a), and the fourth isolation valve 131 is closed at the same time.

[0046] In the overheating stage three (the outlet pressure of the steam generator is 13.9 MPa(a), the outlet temperature of the steam generator ranges from 355°C to 400°C, the medium is superheated steam and the temperature continues to rise, and the flow rate is 36 kg / s), at this time, each isolation valve still maintains the original open and closed state, and the corresponding bypass regulating valve 141 still independently controls the main steam pressure of the corresponding steam generator outlet to be 13.9 MPa(a).

[0047] In the overheating stage four (the outlet pressure of the steam generator is 13.9MPa(a), the outlet temperature of the steam generator is stable at 400℃, the medium is superheated steam, and the flow rate is 36kg / s), when the turbine 2 meets the conditions for starting, it starts to start. At this time, the second isolation valve 112 on the main steam pipeline 11 is gradually opened, so that a part of the main steam is merged into the main steam main pipe 12 along the main steam pipeline 11, and enters the turbine 2 through the main steam valve 122, and the other part still enters the condenser 3 along the corresponding main steam bypass pipeline 14 through the corresponding bypass regulating valve 141. In this process, the bypass regulating valve 141 and the main steam valve 122 jointly regulate the steam generator outlet pressure to 13.9MPa(a), and the opening of the main steam valve 122 gradually increases, and the opening of the bypass regulating valve 141 gradually decreases until it is closed. At this time, the turbine air intake is 36kg / s, and then the steam generator outlet pressure is regulated by the main steam valve 122.

[0048] In the overheating stage five (the outlet pressure of the steam generator is 13.9 MPa(a), the outlet temperature of the steam generator ranges from 400°C to 571°C, the medium is superheated steam, and the flow rate is 36 kg / s), the main steam valve 122 is still used to adjust the outlet pressure of the steam generator to 13.9 MPa(a).

[0049] In overheating stage six (the outlet pressure of the steam generator is 13.9 MPa(a), the outlet temperature of the steam generator is stable at 571 degrees, the medium is superheated steam, and the flow rate increases from 36 kg / s to 96 kg / s corresponding to the full power of a single stack), the corresponding reactor begins to increase power, and the flow rate increases from 36 kg / s to 96 kg / s. During this process, the main steam valve 122 adjusts the outlet pressure of the steam generator to 13.9 MPa(a), and the opening of the main steam valve 122 gradually increases until the corresponding reactor operates at full power.

[0050] (2) Startup condition 2 (subsequent stack startup condition):

[0051] During the startup subcooling stage, saturation stage, superheating stage 1 and superheating stage 2, the system operating status is the same as startup condition 1.

[0052] In the overheating stage three (the outlet pressure of the steam generator is 13.9 MPa(a), the outlet temperature of the steam generator increases from 355°C to 571°C, the medium is superheated steam and the temperature continues to rise, and the flow rate is 36 kg / s), at this time, each isolation valve still maintains the original open and closed state, and the corresponding bypass regulating valve 141 still independently controls the main steam pressure of the corresponding steam generator outlet to be 13.9 MPa(a).

[0053] In the overheating stage four (the outlet pressure of the steam generator is 13.9 MPa(a), the outlet temperature of the steam generator is stable at 571°C, the medium is superheated steam, and the flow rate increases from 36 kg / s to 96 kg / s corresponding to the full power of a single reactor), the second isolation valve 112 on the main steam pipeline 11 is gradually opened, so that a part of the main steam is merged into the main steam main pipe 12 through the main steam pipeline 11 and enters the steam turbine 2 through the main steam valve 122, and the other part still enters the condenser 3 along the corresponding main steam bypass pipeline 14 through the corresponding bypass regulating valve 141. At the same time, the corresponding reactor starts to increase the power, and the flow rate increases from 36 kg / s to 96 kg / s. In this process, the bypass regulating valve 141 regulates the main steam pressure at the outlet of the steam generator to be as stable as possible at 13.9 MPa(a), the opening of the main steam valve 122 gradually increases, and the opening of the bypass regulating valve 141 gradually decreases until the corresponding reactor runs at full power and the corresponding bypass regulating valve 141 is closed.

[0054] The above are preferred implementation modes of the present invention. Those skilled in the art to which the present invention belongs can also change and modify the above implementation modes. Therefore, the present invention is not limited to the above specific implementation modes. Any obvious improvements, substitutions or modifications made by those skilled in the art on the basis of the present invention belong to the protection scope of the present invention.

Claims

1. A 600MW multi-module high temperature reactor start-stop system, characterized by: The invention comprises six steam generators, a steam turbine (2), a condenser (3) and a start-stop reactor expansion vessel (4); each of the steam generators is connected to a main steam main pipe (12) through a main steam pipe (11) and then enters the steam turbine (2) in two ways; a start-stop reactor pipe (13) is led out from the main steam pipe (11) of each steam generator and connected to the start-stop reactor expansion vessel (4); the start-stop reactor adopts a common expansion vessel, a start-stop reactor expansion vessel (4) is arranged on the side of the condenser (3), and the start-stop reactor expansion vessel (4) is connected to the condenser (3) through exhaust and drain pipes; each of the steam generators leads out from the start-stop reactor pipe (13) and then leads out from the main steam bypass pipe (14) to connect to the start-stop reactor expansion vessel (4); the start-stop reactor adopts a common expansion vessel, and a start-stop reactor expansion vessel (4) is arranged on the side of the condenser (3); the start-stop reactor expansion vessel (4) is connected to the condenser (3) through exhaust and drain pipes; each of the steam generators leads out from the start-stop reactor pipe (13) and then leads out from the main steam bypass pipe (14) to connect to the start-stop reactor expansion vessel (4); connected to the condenser (3), each of the main steam bypass pipes (14) is provided with a bypass regulating valve (141); each of the six main steam pipes (11) between the six start-stop pipes (13) and the six main steam bypass pipes (14) is provided with a first isolation valve (111), and each of the main steam pipes (11) between the main steam bypass pipe (14) and the main steam main pipe (12) is provided with a second isolation valve (112); each of the two main steam main pipes (12) is provided with a third isolation valve (121) and a main steam valve (122); each of the start-stop pipes (13) is provided with a fourth isolation valve (131) and a start-stop regulating valve (132).

2. The 600MW multi-module high temperature reactor start-stop system according to claim 1, characterized in that: The steam generators are respectively a first steam generator (101), a second steam generator (102), a third steam generator (103), a fourth steam generator (104), a fifth steam generator (105) and a sixth steam generator (106).

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