Supercritical water power system adapting to deep peak regulation and control method

Abstract

The invention relates to the technical field of boiler water power control, in particular to a supercritical water power system adapting to deep peak shaving and a control method.The system comprises a water cooling wall inlet header, and the water cooling wall inlet header further communicates with a first cooling structure and a second cooling structure; the first cooling structure and the second cooling structure are respectively communicated to the water cooling wall outlet header; the outlet end of the first cooling structure communicates with the inlet end of the second cooling structure through a connecting pipe and is provided with a serial stop valve; a series connection mode is formed when the connecting pipes are connected, and a parallel connection mode is formed when the connecting pipes are disconnected. By adjusting the circulating water path composed of the first cooling structure and the second cooling structure, converting the series connection mode and the parallel connection mode and meeting the load requirements of different structures in actual operation of the system, the peak regulation capacity of the system can be obviously enhanced, the operation power of the system can be rapidly adjusted to meet the actual requirements, and meanwhile energy waste is reduced.

Description

Technical Field

[0001] This invention relates to the field of boiler hydrodynamic control technology, specifically to a supercritical hydrodynamic system and control method adapted to deep peak shaving. Background Technology

[0002] With the continuous optimization of my country's energy structure and the increasing proportion of new energy power generation capacity and output, the volatility and uncertainty of the power system have significantly increased, making system regulation increasingly difficult. To ensure the safe and stable operation of the power grid, coal-fired power plays an increasingly prominent role as a "ballast" in the power system, especially in dealing with extreme weather, sudden load changes, and other special scenarios, where it has irreplaceable strategic significance.

[0003] Against this backdrop, promoting the transformation of coal-fired power units into flexible power sources has become an important direction of the national energy strategy. On the one hand, during peak electricity consumption periods, the unstable or insufficient output of new energy sources such as wind power and photovoltaics makes it difficult to effectively support the peak load demand of the power grid. At this time, coal-fired power units urgently need to have the ability to generate electricity quickly to meet peak demand, providing reliable power support and alleviating the tight supply and demand situation of the power grid. On the other hand, during off-peak electricity consumption periods, the continuous output of renewable energy sources such as wind power and photovoltaics leads to a decrease in the power grid load, resulting in a surplus of electricity supply. At this time, coal-fired power units need to have deep peak-shaving capabilities, enabling them to operate stably under lower load output to cooperate with the absorption of new energy sources and ensure the safety and economy of the system operation. Especially in some regions with large installed capacity of new energy sources and significant differences in load characteristics, the phenomenon of "negative electricity prices" for coal-fired power has already appeared during off-peak electricity consumption periods. Therefore, in the process of building a new power system, further improving the peak-shaving and deep peak-shaving capabilities of coal-fired power units is not only a key measure to ensure the safe and stable operation of the system, but also an important way to improve the economy and survivability of coal-fired power units. This means that coal-fired power units maximize their revenue by operating at peak output during peak load periods, while minimizing output during off-peak periods (the lower the load, the better) to reduce economic losses caused by low-load operation, thereby improving the overall operational efficiency of coal-fired power units throughout their entire life cycle.

[0004] The "Implementation Plan for the Special Action to Upgrade New Generation Coal-fired Power Plants (2025-2027)" requires that the load regulation of existing units above the dry-wet state conversion point be automatically controlled. This means that coal-fired power units can maintain dry-state DC operation even under lower loads. Combined with the requirements for deep peak shaving and ultra-low load, the boiler needs to be deeply peaked to ultra-low load and maintain dry-state DC operation.

[0005] Supercritical boilers possess high power generation efficiency and play a crucial role in peak and deep peak shaving. Under supercritical conditions (steam parameters greater than 22.12 MPa, 374.15℃), the working fluid passes through the furnace evaporation heating surface (surrounding water-cooled walls and water-cooled partitions / screens) in a single pass. The hydrodynamic system, as one of the core subsystems of a supercritical boiler, directly affects the boiler's safety, economy, and regulation capabilities. Currently, the mainstream supercritical hydrodynamic technologies mainly include two structural forms: series and parallel. Series hydrodynamic structure (typical patents CN102012016B and CN202328197U): Water-cooled walls are connected in series with water-cooled partitions / screens on all four sides. Economizer outlet feedwater flows sequentially through the surrounding water-cooled walls and then into the water-cooled partitions / screens. The economizer outlet feedwater first flows through the surrounding water-cooled walls and then enters the water-cooled partitions / screens. This design results in a longer flow path and higher flow resistance (approximately 0.5 MPa, or about 20%, compared to a parallel structure), thus increasing energy consumption during pumping and raising the plant power consumption rate. To reduce resistance and improve economy during peak high-load operation, it is necessary to consider increasing the diameter of the heated surface tubes to reduce the mass flow rate. However, this method leads to an increase in the minimum DC load.

[0006] Parallel hydrodynamic structure (typical patent CN105299634): Water-cooled walls and water-cooled partitions / screens are connected in parallel on all four sides. The economizer outlet feedwater is split into the surrounding water-cooled walls and water-cooled partitions / screens, and after absorbing heat, it merges into the superheater system. The advantage of this method is a shorter water flow path and lower flow resistance, which helps achieve better economic performance under peak high loads. However, when attempting to further reduce the minimum DC load, the mass flow rate may fall below the safe flow rate range, making it impossible to further reduce the minimum DC load.

[0007] The main difference between series and parallel hydrodynamic systems lies in the connection method between the surrounding water-cooled walls and the water-cooled partitions / screens. Currently, neither series nor parallel hydrodynamic systems can simultaneously achieve both economic efficiency at peak loads and lower deep peak-shaving DC loads. The minimum deep peak-shaving DC load can only be achieved around 20%~30% THA (below this, dry-state DC operation cannot be maintained). Therefore, there is an urgent need to propose a new hydrodynamic system structure and its intelligent control strategy to further reduce the minimum deep peak-shaving DC load while maintaining economic efficiency at peak loads. Summary of the Invention

[0008] To address some of the problems existing in the prior art, this invention discloses a supercritical hydrodynamic system and control method adapted to deep peak shaving. By flexibly adjusting between series hydrodynamic and parallel hydrodynamic systems according to actual application conditions, it solves the technical problem that the prior art cannot simultaneously take into account the economy of high peak load and lower deep peak shaving DC load.

[0009] To achieve the above objectives, the power system disclosed in this invention can adopt the following solution: A supercritical hydrodynamic system adapted for deep peak shaving includes a water-cooled wall inlet header, which is also connected to a first cooling structure and a second cooling structure. The first cooling structure and the second cooling structure are respectively connected to a water-cooled wall outlet header. The outlet end of the first cooling structure and the inlet end of the second cooling structure are connected by a connecting pipe, and a series shut-off valve is installed on the connecting pipe. When the connecting pipe connects the first cooling structure and the second cooling structure, a series mode is formed. When the connecting pipe disconnects the first cooling structure and the second cooling structure, a parallel mode is formed.

[0010] The aforementioned hydrodynamic system obtains heat exchange medium from the economizer and other equipment of the system through the water-cooled wall inlet header, and then transports the heat exchange medium to the water-cooled wall outlet header through the first cooling structure and / or the second cooling structure. The first cooling structure and the second cooling structure can be switched to a series mode or a parallel mode to control and regulate the amount of heat exchange medium sent from the water-cooled wall inlet header to the water-cooled wall outlet header. After heat exchange, the heat exchange medium flows out from the water-cooled wall outlet header and is then sent to subsequent superheating equipment for heat exchange, recovering heat for subsequent use.

[0011] Furthermore, considering the changes in the water path between series and parallel modes, the outlet end of the first cooling structure needs adaptive adjustment, thereby changing the way the first cooling structure connects to the water-cooled wall outlet header. Here, an optimization is proposed, and one feasible option is suggested: the outlet end of the first cooling structure is connected to the water-cooled wall outlet header via a first outlet pipe, and a first outlet pipe shut-off valve is installed downstream of the connection point between the first outlet pipe and the connecting pipe. With this scheme, in parallel mode, the first outlet pipe shut-off valve is opened, and the outlet end of the first cooling structure is directly connected to the water-cooled wall outlet header. In series mode, the first outlet pipe shut-off valve is closed, and the outlet end of the first cooling structure is connected to the second cooling structure via a connecting pipe, ultimately reaching the water-cooled wall outlet header through the second cooling structure.

[0012] Furthermore, considering the changes in water path between series and parallel modes, the inlet of the second cooling structure needs adaptive adjustment, thereby changing the water inlet position. Here, an optimization is proposed, and one feasible option is suggested: the inlet of the second cooling structure is connected to the water-cooled wall inlet header via a second inlet pipe, and a second inlet pipe shut-off valve is installed upstream of the connection point between the second inlet pipe and the connecting pipe. Using this scheme, in parallel mode, the second inlet pipe shut-off valve is opened, and the second cooling structure directly receives water from the water-cooled wall inlet header; in series mode, the second inlet pipe shut-off valve is closed, and the second cooling structure receives water from the outlet of the first cooling structure.

[0013] Furthermore, in the series configuration, the first and second cooling structures are connected. To ensure that the heat exchange medium flows only from the first cooling structure to the second cooling structure, an optimization is proposed, and one feasible option is suggested: a check valve is installed on the connecting pipe to prevent water in the second cooling structure from flowing back to the first cooling structure in the series configuration. When the above solution is adopted, the check valve is used to ensure that the heat exchange medium flows unidirectionally from the first cooling structure to the second cooling structure.

[0014] Furthermore, the first and second cooling structures can employ various heat exchange structures, and their structures are not limited to a single one. Here, we optimize and propose one feasible option: the first cooling structure includes four water-cooled walls, and the second cooling structure includes a water-cooled partition wall or a water-cooled screen. When using the above scheme, the first and second cooling structures are respectively located at the corresponding heat exchange locations in the system, thereby achieving heat exchange through the heat exchange medium.

[0015] Furthermore, the surrounding water-cooled walls are used for heat exchange. To improve the effect and efficiency of heat exchange, an optimization is proposed, and one feasible option is suggested: the surrounding water-cooled walls include a rising tube screen, where the diameter of the heat exchange tubes gradually increases from bottom to top. When adopting the above scheme, the cross-sectional area of ​​the upper heat exchange tubes can reach 1.05 to 5 times that of the lower heat exchange tubes.

[0016] Furthermore, the connection positions of the inlet end of the water-cooled wall inlet header and the outlet end of the water-cooled wall outlet header are not uniquely limited. Here, optimization is proposed, and one feasible option is suggested: the inlet end of the water-cooled wall inlet header is connected to the economizer to obtain heat exchange medium from the economizer, and the outlet end of the water-cooled wall outlet header is connected to the heating system to transport the heat exchange medium for heat exchange. When adopting the above scheme, the first and second cooling structures between the water-cooled wall inlet header and the water-cooled wall outlet header can be switched between series and parallel connections to meet the operational requirements under different working conditions.

[0017] The above content discloses a hydrodynamic system. This invention also discloses a hydrodynamic control method, as detailed below: A supercritical hydrodynamic control method adapted to depth peak shaving, employing the supercritical hydrodynamic system described above, includes: When the system is running at a load above the switching load, it adopts a parallel mode, opens the first outlet pipe shut-off valve and the second inlet pipe shut-off valve, and closes the series shut-off valve at the same time, so that the first cooling structure and the second cooling structure switch to parallel mode and respectively deliver heat exchange medium. When the system operates below the load switching level, it adopts a series mode, closing the first outlet pipe shut-off valve and the second inlet pipe shut-off valve, while simultaneously opening the series shut-off valve, so that the first cooling structure and the second cooling structure switch to the series mode and jointly transport the heat exchange medium.

[0018] Furthermore, after the connection method of the first cooling structure and the second cooling structure is changed, the first cooling structure and the second water-cooling mechanism can switch between series and parallel connection. Specifically: when the system is running in parallel mode, the heat exchange medium enters the water-cooled wall inlet header and is divided into two outputs. One output is delivered to the water-cooled wall outlet header through the first cooling structure, and the other output is delivered to the water-cooled wall outlet header through the second cooling structure. When the system is running in series mode, after the heat exchange medium enters the water-cooled wall inlet header, it passes through the first cooling structure and the second cooling structure in sequence before entering the water-cooled wall outlet header.

[0019] In some solutions, the system's operating power varies depending on the mode. After optimization, this invention achieves the following power levels in some solutions: when the system operates in parallel mode, the operating power is greater than or equal to 50% THA (Turbine Heat Acceptance); when the system switches to series mode, the operating power is adjusted to 5% THA to 15% THA. Using the solution of this invention, the power consumption in series mode is significantly lower than the traditional 20% THA to 30% THA, further saving system energy.

[0020] Furthermore, the system's capacity to deliver the heat exchange medium varies depending on the operating mode. Specifically, when the system operates in parallel mode, the water-cooled wall mass flow rate ranges from 400 to 800 kg / m³. 2 •s; When the system operates in series mode, the water-cooled wall mass flow rate ranges from 150 to 600 kg / m³. 2 •s. When adopting the above scheme, the series mode and parallel mode can be adjusted and switched according to changes in requirements, thereby adapting to actual needs.

[0021] Compared with the prior art, some of the beneficial effects of the technical solution disclosed in this invention include: This invention allows for switching between series and parallel modes by adjusting the circulating water path composed of the first and second cooling structures. This caters to the load requirements of different structures during actual system operation, significantly enhancing the system's peak-shaving capability. It enables rapid adjustment of the system's operating power to meet actual needs while reducing energy waste. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the composition and structure of a hydrodynamic system.

[0024] In the above attached figures, the meanings of each label are as follows: 1. Water-cooled wall inlet pipe; 2. Water-cooled wall inlet header; 3. First inlet pipe; 4. First cooling structure; 5. First outlet pipe; 6. Second inlet pipe; 7. Second cooling structure; 8. Second outlet pipe; 9. Connecting pipe; 10. Water-cooled wall outlet header; 11. Water-cooled wall outlet pipe; 12. First outlet shut-off valve; 13. Connecting shut-off valve; 14. Check valve; 15. Second inlet shut-off valve. Detailed Implementation

[0025] The following description, in conjunction with the accompanying drawings and specific embodiments, further illustrates this embodiment.

[0026] In view of the insufficient peak-shaving capacity of existing coal-fired power systems and the resulting energy waste, the following embodiments are optimized and overcome the shortcomings of the existing technology. They solve the problem of insufficient adaptability of existing series and parallel hydrodynamic systems, and while taking into account the economy of peak high load, they break through the traditional 20-30% THA load limit, and the minimum DC operating load can be reduced to 5%-15% THA.

[0027] Example 1 This embodiment provides a supercritical hydrodynamic system adapted to deep peak shaving, including a water-cooled wall inlet header 2, which is also connected to a first cooling structure 4 and a second cooling structure 7. The first cooling structure 4 and the second cooling structure 7 are respectively connected to a water-cooled wall outlet header 10. The outlet end of the first cooling structure 4 and the inlet end of the second cooling structure 7 are connected by a connecting pipe 9, and a series shut-off valve is provided on the connecting pipe 9. When the connecting pipe 9 connects the first cooling structure 4 and the second cooling structure 7, a series mode is formed. When the connecting pipe 9 disconnects the first cooling structure 4 and the second cooling structure 7, a parallel mode is formed.

[0028] The hydrodynamic system disclosed in this embodiment obtains heat exchange medium from the economizer and other equipment of the system through the water-cooled wall inlet header 2, and then transports the heat exchange medium to the water-cooled wall outlet header 10 through the first cooling structure and / or the second cooling structure. The first cooling structure and the second cooling structure can be switched in series or parallel mode to control and regulate the amount of heat exchange medium sent from the water-cooled wall inlet header 2 to the water-cooled wall outlet header 10. After flowing out of the water-cooled wall outlet header 10, the heat exchange medium is sent to subsequent superheating equipment for heat exchange, recovering the heat in the equipment for subsequent use. In this embodiment, the heat exchange medium can be water, which is liquid in the water-cooled wall inlet header 2, gas-liquid mixed in the intermediate first cooling structure and second cooling structure, and mainly gaseous in the water-cooled wall outlet header 10.

[0029] Considering the changes in the water path between series and parallel modes, the outlet end of the first cooling structure 4 needs to be adaptively adjusted, thereby changing the way the first cooling structure 4 connects to the water-cooled wall outlet header 10. This embodiment optimizes this by adopting one feasible option: the outlet end of the first cooling structure 4 is connected to the water-cooled wall outlet header 10 through a first outlet pipe 5, and a stop valve for the first outlet pipe 5 is installed downstream of the connection point between the first outlet pipe 5 and the connecting pipe 9. With the above scheme, in parallel mode, the stop valve for the first outlet pipe 5 is opened, and the outlet end of the first cooling structure 4 is directly connected to the water-cooled wall outlet header 10. In series mode, the stop valve for the first outlet pipe 5 is closed, and the outlet end of the first cooling structure 4 is connected to the second cooling structure 7 through the connecting pipe 9, ultimately reaching the water-cooled wall outlet header 10 through the second cooling structure 7.

[0030] Preferably, in different specific implementation schemes, one or more of the first outlet pipe 5 shut-off valve, the second inlet pipe 6 shut-off valve, and the connecting shut-off valve 13 can be provided as needed in this embodiment. One or more regulating valves, safety valves, and other valves can be added to the system pipeline as needed to ensure convenient and safe operation and adjustment.

[0031] Similarly, considering the changes in water path between series and parallel modes, the inlet end of the second cooling structure 7 needs to be adaptively adjusted to change the water inlet position of the second cooling structure 7. This embodiment optimizes this by adopting one feasible option: the inlet end of the second cooling structure 7 is connected to the water-cooled wall inlet header 2 through the second inlet pipe 6, and a stop valve for the second inlet pipe 6 is installed upstream of the connection point between the second inlet pipe 6 and the connecting pipe 9. When adopting the above scheme, in parallel mode, the stop valve for the second inlet pipe 6 is opened, and the second cooling structure 7 directly receives water from the water-cooled wall inlet header 2; in series mode, the stop valve for the second inlet pipe 6 is closed, and the second cooling structure 7 receives water from the outlet end of the first cooling structure 4.

[0032] In series mode, the first cooling structure 4 and the second cooling structure 7 are connected. To ensure that the heat exchange medium flows only from the first cooling structure 4 to the second cooling structure 7, this embodiment optimizes the process and adopts one feasible option: a check valve 14 is installed on the connecting pipe 9 to prevent water in the second cooling structure 7 from flowing back to the first cooling structure 4 in series mode. When the above solution is adopted, the check valve 14 is used to allow the heat exchange medium to flow unidirectionally from the first cooling structure 4 to the second cooling structure 7.

[0033] The first cooling structure 4 and the second cooling structure 7 can employ various heat exchange structures, and their structures are not limited to a single one. This embodiment optimizes and adopts one feasible option: the first cooling structure 4 includes four water-cooled walls, and the second cooling structure 7 includes a water-cooled partition wall or a water-cooled screen. When the above scheme is adopted, the first cooling structure 4 and the second cooling structure 7 are respectively set at the corresponding locations in the system where heat exchange is required, thereby achieving heat exchange through the heat exchange medium.

[0034] The surrounding water-cooled walls are used for heat exchange. To improve the effect and efficiency of heat exchange, this embodiment is optimized and adopts one feasible option: the surrounding water-cooled walls include a rising tube screen, and the diameter of the heat exchange tubes in the rising tube screen gradually increases from bottom to top. When the above scheme is adopted, the cross-sectional area of ​​the upper heat exchange tubes can reach 1.05 to 5 times that of the lower heat exchange tubes.

[0035] Preferably, the tubes of the water-cooled partition wall or water-cooled screen 7 are arranged inside the furnace, resulting in a larger heating surface area and an inner diameter larger than the diameter of the heat exchange tubes in the surrounding water-cooled walls. Preferably, the water-cooled partition wall or water-cooled screen inlet pipe 6 is located closer to the water-cooled wall inlet pipe 1 than the surrounding water-cooled wall inlet pipes 3 in the water-cooled wall inlet header 2.

[0036] Preferably, the outlet pipe 8 of the water-cooled partition wall or water-cooled screen is located closer to the water-cooled wall outlet pipe 11 than the water-cooled wall outlet pipe 5 around it.

[0037] The connection positions of the inlet end of the water-cooled wall inlet header 2 and the outlet end of the water-cooled wall outlet header 10 are not uniquely limited. This embodiment optimizes the connection and adopts one feasible option: the inlet end of the water-cooled wall inlet header 2 is connected to the economizer to obtain heat exchange medium from the economizer, and the outlet end of the water-cooled wall outlet header 10 is connected to the heating system to transport heat exchange medium for heat exchange. When the above scheme is adopted, the first cooling structure 4 and the second cooling structure 7 between the water-cooled wall inlet header 2 and the water-cooled wall outlet header 10 are switched between series and parallel connections to meet the operating requirements under different working conditions.

[0038] Example 2 The above embodiment 1 discloses a hydrodynamic system. This embodiment discloses a hydrodynamic control method, as follows: A supercritical hydrodynamic control method adapted to depth peak shaving, employing the supercritical hydrodynamic system described in Example 1 above, includes: When the system is running at a load above the switching load, it adopts a parallel mode, opens the first outlet pipe 5 shut-off valve and the second inlet pipe 6 shut-off valve, and closes the series shut-off valve at the same time, so that the first cooling structure 4 and the second cooling structure 7 are switched to parallel mode and respectively transport heat exchange medium. When the system operates below the load switching level, it adopts a series mode, closing the first outlet pipe 5 shut-off valve and the second inlet pipe 6 shut-off valve, while opening the series shut-off valve, so that the first cooling structure 4 and the second cooling structure 7 switch to the series mode and jointly transport the heat exchange medium.

[0039] After the connection method of the first cooling structure 4 and the second cooling structure 7 is changed, the first cooling structure 4 and the second water-cooling mechanism switch between series and parallel connection. Specifically: when the system is running in parallel mode, the heat exchange medium enters the water-cooled wall inlet header 2 and is divided into two outputs. One output is delivered to the water-cooled wall outlet header 10 through the first cooling structure 4, and the other output is delivered to the water-cooled wall outlet header 10 through the second cooling structure 7. When the system is running in series mode, after the heat exchange medium enters the water-cooled wall inlet header 2, it passes through the first cooling structure 4 and the second cooling structure 7 in sequence before entering the water-cooled wall outlet header 10.

[0040] Different operating modes correspond to different system power requirements. After optimization, this invention allows for operation in some schemes as follows: when the system operates in parallel mode, the operating power is greater than or equal to 50% THA; when the system switches to series mode, the operating power is adjusted to 5% THA~15% THA. Using this invention, the power in series mode is significantly lower than the traditional 20% THA~30% THA, further saving system energy. Before switching, the parallel structure significantly reduces the mass flow rate without considering resistance; after switching, the series structure increases the mass flow rate. The design can use smaller diameter water-cooled wall tubes to further increase the mass flow rate at low loads, ensuring safety under even lower mass loads. Thus, by dynamically adjusting the flow path of the hydrodynamic system, both operational economy and lower minimum DC load can be considered.

[0041] The system's capacity to deliver heat exchange medium varies depending on the operating mode. Specifically, when the system operates in parallel mode, the water-cooled wall mass flow rate ranges from 400 to 800 kg / m³. 2 •s; When the system operates in series mode, the water-cooled wall mass flow rate ranges from 150 to 600 kg / m³. 2 •s. When adopting the above scheme, the series mode and parallel mode can be adjusted and switched according to changes in requirements, thereby adapting to actual needs.

[0042] Based on the content disclosed in the above embodiments, two examples are listed here for illustration.

[0043] Case 1 The unit operates at 90% THA and is in parallel operation mode.

[0044] Valve control method: Open the second inlet pipe shut-off valve 15 and the first outlet pipe shut-off valve 12, and close the connecting shut-off valve 13.

[0045] At this point, the feedwater flow path is as follows: after being preheated by the economizer, the feedwater enters the water-cooled wall inlet pipe 1; the feedwater flows into the water-cooled wall inlet header 2, where it is divided into two paths: the first path enters the first cooling structure 4 through the first inlet pipe 3, and after completing heat exchange, it flows out from the surrounding water-cooled wall outlet pipe 5; the second path enters the second cooling structure 7 through the second inlet pipe 6, and after completing heat exchange, it flows out from the second outlet pipe 8; the two fluid paths converge at the water-cooled wall outlet header 10, and finally enter the superheating system through the water-cooled wall outlet pipe 11.

[0046] The working fluid mass flow rate through the first and second cooling structures is 700 kg / m³. 2 The water-cooled wall has low resistance, the feedwater pump has low energy consumption, and the unit has good operating economy.

[0047] The function of check valve 14 is to prevent the working fluid from directly passing through connecting pipe 9, first outlet pipe 5, and water-cooled wall outlet header 10, causing a system short circuit.

[0048] Case 2 The unit operates at a load of 10% THA and is in series operation mode.

[0049] Valve control method: When the THA is 50%, close the first outlet pipe shut-off valve 12 and the second inlet pipe shut-off valve 15; open the connection shut-off valve 13; gradually reduce the load to stabilize at 10% THA.

[0050] The water flow path at this time is: water-cooled wall inlet pipe 1, water-cooled wall inlet header 2, first inlet pipe 3, first cooling structure 4, connecting pipe 9, second cooling structure 7, second outlet pipe 8, water-cooled wall outlet header 10, water-cooled wall outlet pipe 11 → superheating system.

[0051] The working fluid mass flow rate through the first and second cooling structures is 200 kg / m³. 2 •s, the water-cooled wall has a high mass flow rate under low load and good safety.

[0052] After implementing the above embodiments, the following effects can be achieved: Significantly improves adaptability under low load conditions: By optimizing the hydrodynamic flow path and control logic, the minimum DC load can be reduced to 5%~15% THA, breaking through the traditional load limit of 20~30% THA and improving low load safety.

[0053] Significantly improves operational economy: The parallel mode is adopted before switching, which reduces resistance by about 20% compared with the series system and reduces pumping energy consumption by more than 10%, thereby improving the overall economic efficiency of the unit.

[0054] Significantly improves the safety of water-cooled walls under low load: The series structure under low load increases the mass flow rate, and the use of water-cooled wall tubes with smaller diameters further increases the mass flow rate under low load, so that the mass flow rate is kept within a safe range under the lowest DC load. The temperature deviation of the water-cooled wall outlet can be controlled within 20℃, which effectively reduces the thermal stress safety problems caused by temperature differences and improves the safety and stability of boiler operation.

[0055] The above are the embodiments listed in this example; however, this example is not limited to the optional embodiments described above; those skilled in the art can arbitrarily combine the above methods to obtain other various embodiments; anyone can derive other various forms of embodiments under the guidance of this example. The above specific embodiments should not be construed as limiting the scope of protection of this example; the scope of protection of this example should be determined by the claims.

Claims

1. A supercritical hydrodynamic system adapted to deep peak shaving, characterized in that: The system includes a water-cooled wall inlet header (2), which is also connected to a first cooling structure (4) and a second cooling structure (7). The first cooling structure (4) and the second cooling structure (7) are respectively connected to a water-cooled wall outlet header (10). The outlet end of the first cooling structure (4) and the inlet end of the second cooling structure (7) are connected by a connecting pipe (9). A series shut-off valve is provided on the connecting pipe (9). When the connecting pipe (9) connects the first cooling structure (4) and the second cooling structure (7), a series mode is formed. When the connecting pipe (9) disconnects the first cooling structure (4) and the second cooling structure (7), a parallel mode is formed.

2. The supercritical hydrodynamic system adapted to depth peak shaving according to claim 1, characterized in that: The outlet end of the first cooling structure (4) is connected to the water-cooled wall outlet header (10) through the first outlet pipe (5). A stop valve for the first outlet pipe (5) is provided downstream of the connection position between the first outlet pipe (5) and the connecting pipe (9).

3. The supercritical hydrodynamic system adapted to depth peak shaving according to claim 1, characterized in that: The inlet end of the second cooling structure (7) is connected to the water-cooled wall inlet header (2) through the second inlet pipe (6), and a second inlet pipe (6) shut-off valve is provided upstream of the connection position between the second inlet pipe (6) and the connecting pipe (9).

4. The supercritical hydrodynamic system adapted to depth peak shaving according to claim 1, characterized in that: The connecting pipe (9) is equipped with a check valve (14) to prevent water in the second cooling structure (7) from flowing back to the first cooling structure (4) in the series mode.

5. The supercritical hydrodynamic system adapted to depth peak shaving according to claim 1, characterized in that: The first cooling structure (4) includes a surrounding water-cooled wall, and the second cooling structure (7) includes a water-cooled partition wall or a water-cooled screen.

6. The supercritical hydrodynamic system adapted to depth peak shaving according to claim 5, characterized in that: The surrounding water-cooled walls include a riser tube screen, and the diameter of the heat exchange tubes in the riser tube screen gradually increases from bottom to top.

7. The supercritical hydrodynamic system adapted to depth peak shaving according to claim 1, characterized in that: The inlet end of the water-cooled wall inlet header (2) is connected to the economizer and used to obtain heat exchange medium from the economizer. The outlet end of the water-cooled wall outlet header (10) is connected to the heat exchange system and used to transport heat exchange medium for heat exchange.

8. A supercritical hydrodynamic control method adapted to depth peak shaving, characterized in that, The supercritical hydrodynamic system according to any one of claims 1 to 7 comprises: When the system is running at a load above the switching load, it adopts a parallel mode, opens the first outlet pipe (5) shut-off valve and the second inlet pipe (6) shut-off valve, and closes the series shut-off valve at the same time, so that the first cooling structure (4) and the second cooling structure (7) are switched to the parallel mode and respectively transport the heat exchange medium. When the system is running below the load switching, it adopts a series mode, closes the first outlet pipe (5) shut-off valve and the second inlet pipe (6) shut-off valve, and opens the series shut-off valve at the same time, so that the first cooling structure (4) and the second cooling structure (7) switch to the series mode and jointly transport the heat exchange medium.

9. The supercritical hydrodynamic control method for adapting to depth peak shaving according to claim 8, characterized in that: When the system is running in parallel mode, the heat exchange medium enters the water-cooled wall inlet header (2) and is divided into two outputs. One output is delivered to the water-cooled wall outlet header (10) through the first cooling structure (4), and the other output is delivered to the water-cooled wall outlet header (10) through the second cooling structure (7). When the system is running in series mode, after the heat exchange medium enters the water-cooled wall inlet header (2), it passes through the first cooling structure (4) and the second cooling structure (7) in sequence before entering the water-cooled wall outlet header (10).

10. The supercritical hydrodynamic control method for adapting to depth peak shaving according to claim 8, characterized in that: When the system operates in parallel mode, the mass flow rate of the water-cooled wall ranges from 400 to 800 kg / m³. 2 •s; When the system operates in series mode, the water-cooled wall mass flow rate ranges from 150 to 600 kg / m³. 2 ·s.

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