A dual-turbine feedwater regeneration device adaptable to multiple operating conditions

Abstract

This invention relates to a dual-turbine feedwater regeneration device adapted to multiple operating conditions. In addition to being connected to their respective high-pressure heater units, the first and second turbines of the device are also connected as follows: the first high-pressure steam outlet of the first turbine is connected to a fourth high-pressure heater, and the first low-pressure steam outlet of the first turbine is connected to a third high-pressure heater; the second high-pressure steam outlet of the second turbine is connected to a second high-pressure heater, and the second low-pressure steam outlet of the second turbine is connected to the first high-pressure heater. Furthermore, a control module controls the on / off state of the third, fourth, fifth, sixth, seventh, and eighth steam delivery pipelines, enabling the device to meet feedwater regeneration requirements under different equipment conditions, thereby ensuring the safety and efficiency of the entire thermal system.

Description

Technical Field

[0001] Several embodiments of this specification relate to the field of steam turbine feedwater regeneration technology, specifically to a dual-steam turbine feedwater regeneration device adapted to multiple operating conditions. Background Technology

[0002] Currently, conventional feedwater regeneration systems primarily employ a single steam turbine configuration. The operating logic involves heating the first cascaded high-pressure heater via the turbine's intermediate-pressure extraction port, and then heating the second high-pressure heater via an even higher-pressure extraction port, thus creating a staged heating regeneration process. This mode effectively recovers the steam heat within the turbine and is a fundamental configuration for improving unit thermal efficiency. To further meet higher regeneration demands, modern large-scale units are beginning to adopt dual-turbine or multi-turbine feedwater regeneration modes.

[0003] However, current multi-turbine feedwater regeneration systems generally operate independently, with each turbine fixed to a specific heating task, lacking a flexible coordination and switching mechanism. This design reveals significant drawbacks in actual operation: if the turbines operate continuously for extended periods, their failure rate increases significantly, raising the safety risks to the unit. Furthermore, if one turbine shuts down due to a malfunction or maintenance, its heating steam supply is interrupted, directly causing some high-pressure heaters to malfunction, resulting in a substantial decrease in feedwater regeneration efficiency and severely impacting the unit's operational stability.

[0004] Therefore, existing technological solutions are rigid and vulnerable when dealing with equipment failures and changes in operating conditions. To solve this problem and ensure that the unit maintains efficient and stable thermal performance under various operating conditions, the industry urgently needs to develop a dual-turbine feedwater regeneration device that can flexibly adapt to multiple operating conditions. This device should be able to meet the feedwater regeneration requirements under different equipment states (single-unit operation, dual-unit operation), thereby ensuring the safety and efficiency of the entire thermal system. Summary of the Invention

[0005] This specification provides an embodiment of a dual-turbine feedwater regeneration device that is adaptable to multiple operating conditions. It can meet the feedwater regeneration requirements under different equipment states (single-unit operation, dual-unit operation), thereby ensuring the safety and efficiency of the entire thermal system.

[0006] The technical solution is as follows: In the first aspect, the embodiments of this specification provide a dual-turbine feedwater regeneration device adapted to multiple operating conditions, including a first turbine, a second turbine, a first high-pressure heater, a second high-pressure heater, a third high-pressure heater, a fourth high-pressure heater, a boiler, a deaerator, a water source, and a control module; The first steam turbine includes a first high-pressure steam outlet, a first intermediate-pressure steam outlet, and a first low-pressure steam outlet; the second steam turbine includes a second high-pressure steam outlet, a second intermediate-pressure steam outlet, and a second low-pressure steam outlet. A first water supply pipeline, running from the water source to the boiler, connects the water source, deaerator, first high-pressure heater, second high-pressure heater, and boiler. A second water supply pipeline, also running from the water source to the boiler, connects the water source, deaerator, third high-pressure heater, fourth high-pressure heater, and boiler. The first high-pressure steam outlet is connected to the second high-pressure heater inlet and the fourth high-pressure heater inlet via a first steam supply pipeline and a second steam supply pipeline, respectively; the first medium-pressure steam outlet is connected to the first high-pressure heater inlet via a third steam supply pipeline; and the first low-pressure steam outlet is connected to the third high-pressure heater inlet via a fourth steam supply pipeline. The second high-pressure steam outlet is connected to the second high-pressure heater inlet and the fourth high-pressure heater inlet via a fifth and a sixth steam supply pipeline, respectively; the second medium-pressure steam outlet is connected to the third high-pressure heater inlet via a seventh steam supply pipeline; and the second low-pressure steam outlet is connected to the first high-pressure heater inlet via an eighth steam supply pipeline. The control module controls the on / off state of the third, fourth, fifth, sixth, seventh, and eighth steam pipelines based on the on / off status of the first and second steam turbines.

[0007] As a preferred option, both the fourth and eighth steam supply pipelines are connected to the steam supply pipelines leading to the user end.

[0008] As a preferred embodiment, a first regulating valve is installed on the pipeline connected to the steam inlet of the second high-pressure heater to control the flow rate of the steam fed into the second high-pressure heater. A second regulating valve is installed on the pipeline connected to the steam inlet of the fourth high-pressure heater to control the flow rate of the steam fed into the fourth high-pressure heater.

[0009] As a preferred embodiment, a third regulating valve is installed on the third steam supply pipeline to control the flow rate of the steam supplied from the third steam supply pipeline to the first high-pressure heater; A fourth regulating valve is installed on the seventh steam supply pipeline to control the flow rate of the steam supplied from the seventh steam supply pipeline to the third high-pressure heater.

[0010] As a preferred embodiment, a fifth regulating valve is installed on the fourth steam supply pipeline to control the flow rate of the steam supplied from the fourth steam supply pipeline to the third high-pressure heater; A sixth regulating valve is installed on the eighth steam supply pipeline to control the flow rate of the steam supplied from the eighth steam supply pipeline to the first high-pressure heater.

[0011] As a preferred embodiment, a first drain line is connected between the second high-pressure heater and the first high-pressure heater, and a second drain line is connected between the first high-pressure heater and the deaerator. A first vapor-liquid two-phase drain valve is installed at the first drain line, and a first drain regulating valve is installed at the second drain line. A third drain line is connected between the fourth high-pressure heater and the third high-pressure heater, and a fourth drain line is connected between the third high-pressure heater and the deaerator. A second vapor-liquid two-phase drain valve is installed at the third drain line, and a second drain regulating valve is installed at the fourth drain line. The control module combines the target water level and the real-time water level in the first high-pressure heater, and calls the water level PID control model to control the opening of the first drainage regulating valve. The control module, in conjunction with the target water level and the real-time water level in the third high-pressure heater, calls the water level PID control model to control the opening degree of the second drainage regulating valve.

[0012] As a preferred embodiment, the control module controls the on / off state of the third, fourth, fifth, sixth, seventh, and eighth steam delivery pipelines based on the on / off states of the first and second steam turbines, including: When both the first and second steam turbines are in the start-up state, the first, second, third, fifth, sixth, and seventh steam delivery pipelines are controlled to be in the conducting state, and the fourth and eighth steam delivery pipelines are controlled to be in the cut-off state. When the first steam turbine is in shutdown state and the second steam turbine is in startup state, the fifth, sixth, seventh, and eighth steam supply pipelines are controlled to be in the conducting state, and the first, second, third, and fourth steam supply pipelines are controlled to be in the shut-off state. When the second steam turbine is shut down and the first steam turbine is running, the first, second, third, and fourth steam delivery pipelines are controlled to be in the on state, and the fifth, sixth, seventh, and eighth steam delivery pipelines are controlled to be in the off state.

[0013] As a preferred option, a parameter acquisition module is also included; The parameter acquisition module acquires the target temperature of hot water and the real-time temperature of hot water inside the boiler. The control module, based on the on / off status of the first and second steam turbines, calls the corresponding temperature PID control model and combines the target hot water temperature and the real-time hot water temperature to control the opening degree of the regulating valves on each steam pipeline that is currently in the conducting state.

[0014] As a preferred solution, when both the first and second steam turbines are in the start-up state, the control module combines the target hot water temperature and the real-time hot water temperature, and calls the first temperature PID control model to control the opening degree of the first and second regulating valves, and calls the second temperature PID control model to control the opening degree of the third and fourth regulating valves. The control module, when the first steam turbine is in a shutdown state and the second steam turbine is in a startup state, combines the target parameters of hot water and the real-time parameters of hot water, and calls the third temperature PID control model to control the opening of the first regulating valve and the second regulating valve, calls the second temperature PID control model to control the opening of the fourth regulating valve, and calls the fourth temperature PID control model to control the opening of the sixth regulating valve. The control module, when the second steam turbine is in a stopped state and the first steam turbine is in a started state, combines the target parameters of hot water and the real-time parameters of hot water, and calls the third temperature PID control model to control the opening degree of the first regulating valve and the second regulating valve, calls the second temperature PID control model to control the opening degree of the third regulating valve, and calls the fourth temperature PID control model to control the opening degree of the fifth regulating valve.

[0015] As a preferred embodiment, a parameter update module is also included; the parameter update module includes a first parameter acquisition unit, a second parameter acquisition unit, and a parameter update unit; The first parameter acquisition unit acquires the current hot water temperature error and the rate of change of the hot water temperature error. The second parameter acquisition unit acquires the current steam supply flow rate at the user end and the rate of change of the steam supply flow rate at the user end. The parameter update unit updates the model parameters of the fourth PID control model based on the fuzzy control algorithm when the first or second steam turbine is out of service, taking into account the current hot water temperature error, the rate of change of hot water temperature error, the current steam supply flow rate at the user end, and the rate of change of steam supply flow rate at the user end.

[0016] The beneficial effects of the technical solutions provided in some embodiments of this specification include at least the following: In addition to being connected to their respective high-pressure heater units, the first and second steam turbines are also connected to the fourth high-pressure heater via their respective high-pressure outlets. The first low-pressure outlet of the first steam turbine is also connected to the third high-pressure heater. The second high-pressure outlet of the second steam turbine is also connected to the second high-pressure heater, and the second low-pressure outlet of the second steam turbine is also connected to the first high-pressure heater. Furthermore, the control module controls the opening and closing of the third, fourth, fifth, sixth, seventh, and eighth steam pipelines, enabling the device to meet the feedwater reheat requirements under different equipment states (single-unit operation and dual-unit operation), thereby ensuring the safety and efficiency of the entire thermal system. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of the overall structure of a dual-turbine feedwater regeneration device adapted to multiple operating conditions, according to some embodiments of the present disclosure, is shown.

[0019] In the diagram: 1. First steam turbine; 11. First isolation valve; 12. Second isolation valve; 13. First regulating valve; 14. First high-pressure steam outlet; 15. First intermediate-pressure steam outlet; 151. Third isolation valve; 152. Third regulating valve; 16. First low-pressure steam outlet; 161. Fourth isolation valve; 162. Fifth regulating valve; 163. Fifth isolation valve; 2. Second steam turbine; 21. Sixth isolation valve; 22. Seventh isolation valve; 23. Second regulating valve; 24. Second high-pressure steam outlet; 25. Second intermediate-pressure steam outlet; 251. Eighth isolation valve; 252. Fourth regulating valve; 26. 1. Second low-pressure steam outlet; 261. Ninth isolation valve; 262. Sixth regulating valve; 263. Tenth isolation valve; 3. First high-pressure heater; 31. First drain regulating valve; 32. Steam inlet of first high-pressure heater; 4. Second high-pressure heater; 41. First vapor-liquid two-phase drain; 42. Steam inlet of second high-pressure heater; 5. Third high-pressure heater; 51. Second drain regulating valve; 52. Steam inlet of third high-pressure heater; 6. Fourth high-pressure heater; 61. Second vapor-liquid two-phase drain; 62. Steam inlet of fourth high-pressure heater; 7. Deaerator; 8. Steam separator; 9. Boiler. Detailed Implementation

[0020] The technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings.

[0021] The terms "first," "second," "third," etc., in the description, claims, and accompanying drawings are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such processes, methods, products, or apparatus.

[0022] The following description provides examples and does not limit the scope, applicability, or examples set forth in the claims. Changes may be made to the function and arrangement of the described elements without departing from the scope of this specification. Various processes or components may be appropriately omitted, substituted, or added to the examples. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Furthermore, features described with respect to some examples may be combined into other examples.

[0023] Figure 1 A schematic diagram of the overall structure of a dual-turbine feedwater regeneration device adapted to multiple operating conditions, according to some embodiments of this disclosure, is shown. Figure 1 As shown, the feedwater regeneration device may include at least a first steam turbine 1, a second steam turbine 2, a first high-pressure heater 3, a second high-pressure heater 4, a third high-pressure heater 5, a fourth high-pressure heater 6, a boiler 9, a deaerator 7, a water source, and a control module. The first steam turbine 1 includes a first high-pressure steam outlet 14, a first intermediate-pressure steam outlet 15, and a first low-pressure steam outlet 16; the second steam turbine 2 includes a second high-pressure steam outlet 24, a second intermediate-pressure steam outlet 25, and a second low-pressure steam outlet 26. A first water supply pipeline connecting the water source, deaerator 7, first high-pressure heater 3, second high-pressure heater 4, and boiler 9, extending from the water source to the boiler 9; and a second water supply pipeline connecting the water source, deaerator 7, third high-pressure heater 5, fourth high-pressure heater 6, and boiler 9, extending from the water source to the boiler 9. The first high-pressure steam outlet 14 is connected to the second high-pressure heater inlet 42 and the fourth high-pressure heater inlet 62 by a first steam supply pipeline and a second steam supply pipeline, respectively; the first medium-pressure steam outlet 15 is connected to the first high-pressure heater inlet 32 ​​by a third steam supply pipeline; and the first low-pressure steam outlet 16 is connected to the third high-pressure heater inlet 52 by a fourth steam supply pipeline. The second high-pressure steam outlet 24 is connected to the second high-pressure heater inlet 42 and the fourth high-pressure heater inlet 62 by a fifth steam supply pipeline and a sixth steam supply pipeline, respectively; the second medium-pressure steam outlet 25 is connected to the third high-pressure heater inlet 52 by a seventh steam supply pipeline; and the second low-pressure steam outlet 26 is connected to the first high-pressure heater inlet 32 ​​by an eighth steam supply pipeline. The control module controls the on / off state of the third, fourth, fifth, sixth, seventh, and eighth steam pipelines based on the on / off status of the first steam turbine 1 and the second steam turbine 2.

[0024] Understandably, in addition to being connected to their respective high-pressure heater units, the first high-pressure steam outlet 14 of the first steam turbine 1 is also connected to the fourth high-pressure heater 6, the first low-pressure steam outlet 16 of the first steam turbine 1 is also connected to the third high-pressure heater 5, the second high-pressure steam outlet 24 of the second steam turbine 2 is also connected to the second high-pressure heater 4, and the second low-pressure steam outlet 26 of the second steam turbine 2 is also connected to the first high-pressure heater 3. Furthermore, the control module controls the on / off state of the third, fourth, fifth, sixth, seventh, and eighth steam pipelines, enabling the device to meet the feedwater reheat requirements under different equipment states (single-unit operation, dual-unit operation), thereby ensuring the safety and efficiency of the entire thermal system.

[0025] It should be noted that changes in equipment status may be due to shutdowns caused by turbine malfunctions or normal shutdowns scheduled for rest periods.

[0026] Specifically, the equipment status is mainly divided into the following three types: I. Both the first steam turbine 1 and the second steam turbine 2 are in the starting state: At this time, the steam from the first high-pressure steam outlet 14 of the first steam turbine 1 is directed to the second high-pressure heater 4, and the steam from the first medium-pressure steam outlet 15 of the first steam turbine 1 is directed to the first high-pressure heater 3. Thus, the output steam from the first steam turbine 1 enables the first high-pressure heater 3 and the second high-pressure heater 4 to heat the water in stages. The steam from the second high-pressure outlet 24 of the second steam turbine 2 is directed to the fourth high-pressure heater 6, and the steam from the second intermediate-pressure outlet 25 of the second steam turbine 4 is directed to the third high-pressure heater 5. Thus, the steam output from the second steam turbine 2 enables the third high-pressure heater 5 and the fourth high-pressure heater 6 to heat the water in stages.

[0027] II. First steam turbine 1 is in the starting state, and second steam turbine 2 is in the shutdown state: At this time, the steam from the first high-pressure steam outlet 14 of the first steam turbine 1 is directed to the second high-pressure heater 4 and the fourth high-pressure heater 6, respectively; the steam from the first medium-pressure steam outlet 15 of the first steam turbine 1 is directed to the first high-pressure heater 3; and the steam from the first low-pressure steam outlet 16 of the first steam turbine 1 is directed to the third high-pressure heater 5. Thus, the output steam from the first steam turbine 1 enables the first high-pressure heater 3 and the second high-pressure heater 4 to heat the water in stages, and enables the third high-pressure heater 5 and the fourth high-pressure heater 6 to heat the water in stages. III. The second steam turbine 2 is in the running state, and the first steam turbine 1 is in the shutdown state: At this time, the steam from the second high-pressure steam outlet 24 of the second steam turbine 2 is directed to the second high-pressure heater 4 and the fourth high-pressure heater 6, respectively. The steam from the second intermediate-pressure steam outlet 25 of the second steam turbine 2 is directed to the third high-pressure heater 5, and the steam from the second low-pressure steam outlet 26 of the second steam turbine 2 is directed to the first high-pressure heater 3. Thus, the output steam from the second steam turbine 2 enables the first high-pressure heater 3 and the second high-pressure heater 4 to heat the water in stages, and enables the third high-pressure heater 5 and the fourth high-pressure heater 6 to heat the water in stages.

[0028] It should be noted that the steam turbine used in this specification has at least three steam outlets. The steam performs work in stages within the turbine, with its pressure and temperature decreasing progressively. Therefore, the pressure and temperature of the steam output from the three outlets also decrease sequentially. Specifically, the steam from the intermediate-pressure outlet provides initial heating to the water in the high-pressure heater, while the steam from the high-pressure outlet further heats the water in the high-pressure heater, thus creating a staged heating process. Furthermore, the steam from the low-pressure outlet, due to its larger volume, is used to supply steam to external users who require it.

[0029] Furthermore, it should be noted that in the feedwater regeneration system, a pressure difference must exist between the high-pressure heaters that heat the water in each stage; otherwise, the water formed after heat exchange in the high-pressure heaters cannot flow back to the deaerator 7 for deoxygenation and reuse. Therefore, the following explanation is based on the equipment state where the first turbine 1 is in the start-up state and the second turbine 2 is in the shutdown state. In this state, there are three steam dispatching methods for the first turbine 1 (Note: the steam dispatching logic is the same when the first turbine 1 is in the shutdown state and the second turbine 2 is in the start-up state, so it will not be elaborated here): 1. Transfer the steam from the first high-pressure steam outlet 14 to the fourth high-pressure heater 6, and transfer the steam from the first medium-pressure steam outlet 15 to the third high-pressure heater 5. 2. Transfer the steam from the first medium-pressure steam outlet 15 to the fourth high-pressure heater 6, and transfer the steam from the first low-pressure steam outlet 16 to the third high-pressure heater 5. Third, transfer the steam from the first high-pressure steam outlet 14 to the fourth high-pressure heater 6, and transfer the steam from the first low-pressure steam outlet 16 to the third high-pressure heater 5.

[0030] In the first calling method, since the amount of steam from the first medium-pressure steam outlet 15 is small, if the steam from this outlet needs to be distributed to the third high-pressure heater 5 and the first high-pressure heater 3 respectively, the primary heating of the water will inevitably be insufficient. Although there is a subsequent step of advanced heating through high-pressure steam, the degree of insufficient primary heating will still result in the inability to reach the target temperature of the hot water. In the second calling method, the medium-pressure steam performs the final heating stage. However, the pressure and temperature of the steam at the first medium-pressure steam outlet 15 are not high enough, and the amount of steam at the first medium-pressure steam outlet 15 is also insufficient. Therefore, the target hot water temperature requirement cannot be achieved in the end. In the third calling method, although the pressure and temperature of the steam at the first low-pressure steam outlet 16 are not high enough, the amount of steam at the first low-pressure steam outlet 16 is large and the output is stable. Therefore, the primary heating effect can be guaranteed by increasing the flow rate. Furthermore, there is a backup heating stage for advanced heating by high-pressure steam. Therefore, by adopting this calling method, the target temperature requirement for hot water can be achieved in the end.

[0031] In some embodiments of this specification, both the fourth steam supply pipeline and the eighth steam supply pipeline are connected to the steam supply pipeline leading to the user end, that is, the low-pressure steam generated by the steam turbine can be supplied to the user end.

[0032] In addition, the fourth and eighth steam supply pipelines can share a pipeline, and a steam distribution cylinder 8 can be installed on the shared pipeline. The steam supply pipeline to the user can be installed on the steam distribution cylinder 8, thereby reducing the number of pipelines.

[0033] In the actual application of steam turbines, the steam output from the low-pressure outlet is greater than that from the high-pressure outlet, which is greater than that from the intermediate-pressure outlet. Therefore, if the steam output from the high-pressure outlet is also sufficient, a steam supply pipeline for supplying high-pressure steam to the user can also be set up. Of course, a steam distribution cylinder can also be set up on the steam supply pipeline for supplying high-pressure steam. The specific setup can be determined according to the actual situation.

[0034] In some embodiments of this specification, a first regulating valve 13 is provided on the pipeline connected to the steam inlet 42 of the second high-pressure heater to control the flow rate of the steam fed into the second high-pressure heater 4; and a second regulating valve 23 is provided on the pipeline connected to the steam inlet 62 of the fourth high-pressure heater to control the flow rate of the steam fed into the fourth high-pressure heater 6.

[0035] In some embodiments of this specification, a third regulating valve 152 is provided on the third steam supply pipeline to control the flow rate of the steam supplied from the third steam supply pipeline to the first high-pressure heater 3; and a fourth regulating valve 252 is provided on the seventh steam supply pipeline to control the flow rate of the steam supplied from the seventh steam supply pipeline to the third high-pressure heater 5.

[0036] In some embodiments of this specification, a fifth regulating valve 162 is provided on the fourth steam supply pipeline to control the flow rate of the steam supplied from the fourth steam supply pipeline to the third high-pressure heater 5; A sixth regulating valve 262 is installed on the eighth steam supply pipeline to control the flow rate of the steam supplied from the eighth steam supply pipeline to the first high-pressure heater 3.

[0037] It is understandable that the target temperature of hot water can be adjusted. Therefore, it is necessary to install corresponding regulating valves on each steam supply pipeline to regulate the flow of steam into the high-pressure heater, thereby achieving the purpose of controlling the water temperature.

[0038] In some embodiments of this specification, a first drain line is connected between the second high-pressure heater 4 and the first high-pressure heater 3, and a second drain line is connected between the first high-pressure heater 3 and the deaerator 7. A first vapor-liquid two-phase drain 41 is installed at the first drain line, and a first drain regulating valve 31 is installed at the second drain line; a third drain line is connected between the fourth high-pressure heater 6 and the third high-pressure heater 5, and a fourth drain line is connected between the third high-pressure heater 5 and the deaerator 7. A second vapor-liquid two-phase drain 61 is installed at the third drain line, and a second drain regulating valve 51 is installed at the fourth drain line; The control module, in conjunction with the target water level and the real-time water level in the first high-pressure heater 3, calls the water level PID control model to control the opening degree of the first drain regulating valve 31. The control module, in conjunction with the target water level and the real-time water level in the third high-pressure heater 5, calls the water level PID control model to control the opening degree of the second drainage regulating valve 51.

[0039] The explanation will be based on the first high-pressure heater 3 and the second high-pressure heater 4 as examples: Understandably, after steam enters the high-pressure heater for heat exchange, it liquefies to form water, which then settles inside the high-pressure heater. Since the internal steam pressure of the second high-pressure heater 4, the first high-pressure heater 3, and the deaerator 7 decreases progressively, the settled water can flow back to the deaerator 7 sequentially from the second high-pressure heater 4 and the first high-pressure heater 3. However, excessively high water levels in the high-pressure heaters will lead to a drop in the final feedwater temperature, affecting economic efficiency and posing a risk of backflow into the turbine, causing water hammer and seriously threatening equipment safety. Conversely, excessively low water levels will result in steam in the condensate, leading to decreased heat exchange efficiency, increased heat consumption, and increased risk of pipe erosion and pipe bursts. Therefore, the water level in the high-pressure heaters needs to be controlled accordingly. Furthermore, since the first high-pressure heater 3 and the second high-pressure heater 4 are cascaded, a first condensate regulating valve 31 with adjustable flow rate can be installed at the second condensate line to indirectly control the water level in the second high-pressure heater 4 while simultaneously controlling the water level in the first high-pressure heater 3. Specifically, the target water level and the real-time water level inside the first high-pressure heater 3 can be combined, and the opening degree of the first drain regulating valve 31 can be controlled by calling the water level PID control model, thereby realizing the water level control inside the high-pressure heater.

[0040] In some embodiments of this specification, the control module controls the on / off state of the third, fourth, fifth, sixth, seventh, and eighth steam delivery pipelines based on the on / off states of the first steam turbine 1 and the second steam turbine 2, including: When both the first steam turbine 1 and the second steam turbine 2 are in the start-up state, the first steam delivery pipeline, the second steam delivery pipeline, the third steam delivery pipeline, the fifth steam delivery pipeline, the sixth steam delivery pipeline, and the seventh steam delivery pipeline are controlled to be in the conducting state, and the fourth steam delivery pipeline and the eighth steam delivery pipeline are controlled to be in the cut-off state. Reference Figure 1 As shown, in Figure 1 In the pipeline design shown, when both the first turbine 1 and the second turbine 2 are running, the control module controls the first isolation valve 11, the second isolation valve 12, the third isolation valve 151, the sixth isolation valve 21, the seventh isolation valve 22, and the eighth isolation valve 251 to be open, while controlling the fifth isolation valve 163 and the tenth isolation valve 263 to be closed. Furthermore, the control module also controls the fourth isolation valve 161 and the ninth isolation valve 261 to be open to provide low-pressure steam to the user end.

[0041] When the first steam turbine 1 is in the off state and the second steam turbine 2 is in the on state, the fifth, sixth, seventh, and eighth steam supply pipelines are controlled to be in the conducting state, and the first, second, third, and fourth steam supply pipelines are controlled to be in the cut-off state. Reference Figure 1 As shown, in Figure 1 In the pipeline design shown, when the first turbine 1 is in a shutdown state and the second turbine 2 is in a startup state, the control module controls the first isolation valve 11, the third isolation valve 151, the fourth isolation valve 161, and the fifth isolation valve 163 to close, and the control module controls the sixth isolation valve 21, the second isolation valve 12, the seventh isolation valve 22, the eighth isolation valve 251, the ninth isolation valve 261, and the tenth isolation valve 263 to open.

[0042] When the second steam turbine 2 is in the off state and the first steam turbine 1 is in the on state, the first steam delivery pipeline, the second steam delivery pipeline, the third steam delivery pipeline, and the fourth steam delivery pipeline are controlled to be in the conducting state, and the fifth steam delivery pipeline, the sixth steam delivery pipeline, the seventh steam delivery pipeline, and the eighth steam delivery pipeline are controlled to be in the cut-off state.

[0043] Reference Figure 1 As shown, in Figure 1In the pipeline design shown, when the second turbine 2 is in a stopped state and the first turbine 1 is in a running state, the control module controls the sixth isolation valve 21, the eighth isolation valve 251, the ninth isolation valve 261, and the tenth isolation valve 263 to close, and the control module controls the first isolation valve 11, the second isolation valve 12, the seventh isolation valve 22, the third isolation valve 151, the fourth isolation valve 161, and the fifth isolation valve 163 to open.

[0044] In some embodiments of this specification, the dual-turbine feedwater regeneration device further includes a parameter acquisition module; The parameter acquisition module acquires the target temperature of hot water and the real-time temperature of hot water inside boiler 9. The control module, based on the on / off states of the first steam turbine 1 and the second steam turbine 2, calls the corresponding temperature PID control model and, in conjunction with the target hot water temperature and the real-time hot water temperature, controls the opening degree of the regulating valves on each steam delivery pipeline that is currently in the conducting state.

[0045] As described above, the target temperature of the hot water can be adjusted. Therefore, it is necessary to install corresponding regulating valves on each steam supply pipeline to regulate the flow rate of steam into the high-pressure heater, thereby controlling the water temperature. In several embodiments of this specification, a temperature PID control model is used to control the opening degree of the regulating valves, thereby achieving the purpose of controlling the water temperature.

[0046] In addition, it should be noted that the steam supplied to the turbines differs depending on the on / off state of the first turbine 1 and the second turbine 2.

[0047] Scenario 1: When both the first turbine 1 and the second turbine 2 are running, high-pressure steam is supplied to the second high-pressure heater 4 and the fourth high-pressure heater 6; medium-pressure steam is supplied to the first high-pressure heater 3 and the third high-pressure heater 5.

[0048] Scenario 2: When the first turbine 1 is shut down and the second turbine 2 is running, high-pressure steam is supplied to the second high-pressure heater 4 and the fourth high-pressure heater 6. However, since both are supplied through the second turbine 2, the steam flow rate entering the second high-pressure heater 4 and the fourth high-pressure heater 6 will be lower than in Scenario 1, provided the regulating valve openings are consistent. Medium-pressure steam is supplied to the third high-pressure heater 5, and the steam conditions are the same as in Scenario 1. Low-pressure steam is supplied to the first high-pressure heater 3, and the steam pressure and temperature are lower than in Scenario 1.

[0049] Scenario 3: When the first turbine 1 is running and the second turbine 2 is shut down, high-pressure steam is supplied to the second high-pressure heater 4 and the fourth high-pressure heater 6. However, since both are supplied by the first turbine 1, the steam flow rate entering the second high-pressure heater 4 and the fourth high-pressure heater 6 will be lower than in Scenario 1, provided that the regulating valve openings are consistent. Medium-pressure steam is supplied to the first high-pressure heater 3, and the steam conditions are consistent with those in Scenario 1. Low-pressure steam is supplied to the third high-pressure heater 5, and the steam pressure and temperature are lower than in Scenario 1.

[0050] Therefore, the control module needs to call the corresponding temperature PID control model based on the on / off state of the first steam turbine 1 and the second steam turbine 2, and combine the target hot water temperature and the real-time hot water temperature to control the opening degree of the regulating valves on each steam pipeline that is currently in the conducting state, instead of always using the same temperature PID control model.

[0051] It should be added that the high-pressure steam, medium-pressure steam, and low-pressure steam output by the steam turbine also show a gradual decrease in temperature. Therefore, the high-pressure steam, medium-pressure steam, and low-pressure steam described above correspond to high-temperature steam, medium-temperature steam, and low-temperature steam, respectively.

[0052] In some embodiments of this specification, under the three steam conditions described above: The control module, when both the first steam turbine 1 and the second steam turbine 2 are in the start-up state, combines the target temperature of hot water and the real-time temperature of hot water, and calls the first temperature PID control model to control the opening degree of the first regulating valve 13 and the second regulating valve 23, and calls the second temperature PID control model to control the opening degree of the third regulating valve 152 and the fourth regulating valve 252. The control module, when the first steam turbine 1 is in the off state and the second steam turbine 2 is in the on state, combines the target hot water parameters and real-time hot water parameters, and calls the third temperature PID control model to control the opening of the first regulating valve 13 and the second regulating valve 23, calls the second temperature PID control model to control the opening of the fourth regulating valve 252, and calls the fourth temperature PID control model to control the opening of the sixth regulating valve 262. When the second steam turbine 2 is in a stopped state and the first steam turbine 1 is in a started state, the control module combines the target parameters and real-time parameters of hot water, and calls the third temperature PID control model to control the opening of the first regulating valve 13 and the second regulating valve 23, calls the second temperature PID control model to control the opening of the third regulating valve 152, and calls the fourth temperature PID control model to control the opening of the fifth regulating valve 162.

[0053] Understandably, when either the first turbine 1 or the second turbine 2 is shut down, the low-pressure steam needs to be supplied not only to external users but also to the high-pressure heaters inside the unit for heat exchange. Therefore, changes in the steam flow rate to the users will also affect the steam supply to the high-pressure heaters. Consequently, in some embodiments of this specification, the dual-turbine feedwater regeneration device further includes a parameter update module; the parameter update module includes a first parameter acquisition unit, a second parameter acquisition unit, and a parameter update unit. The first parameter acquisition unit acquires the current hot water temperature error and the rate of change of the hot water temperature error. The second parameter acquisition unit acquires the current steam supply flow rate at the user end and the rate of change of the steam supply flow rate at the user end. The parameter update unit updates the parameters of the fourth PID control model based on the fuzzy control algorithm when the first steam turbine 1 or the second steam turbine 2 is in a shutdown state. This update is done in conjunction with the current hot water temperature error, the rate of change of hot water temperature error, the current steam supply flow rate at the user end, and the rate of change of steam supply flow rate at the user end.

[0054] Understandably, traditional PID controllers adjust system errors through proportional, integral, and derivative gain components. Furthermore, the proportional gain, integral gain, and derivative gain coefficients of traditional PID controllers are fixed, making them unsuitable for complex, nonlinear, or time-varying systems. If control parameters are output using only fixed proportional, integral, and derivative gain coefficients, it will be insufficient to ensure the hot water temperature remains stable at the target temperature. Therefore, in this embodiment, a fuzzy control algorithm is used, combined with the current hot water temperature error, the rate of change of the hot water temperature error, the current steam supply flow rate at the user end, and the rate of change of the steam supply flow rate at the user end, to update the model parameters of the fourth PID control model. In this embodiment, the fuzzy control rules prioritize the proportional and derivative gain coefficients; in other embodiments, control of the integral gain coefficient may also be added.

[0055] In the embodiments of this specification, the logic for updating model parameters by combining the current hot water temperature error, the rate of change of the hot water temperature error, the current steam supply flow rate at the user end, and the rate of change of the steam supply flow rate at the user end may include, but is not limited to, the following (Note: Due to the large number of possible situations, only two cases are given as examples for illustration): 1. If the current hot water temperature error is positive and large, the hot water temperature error change rate is negative and high, the current steam supply flow rate at the user end is large, and the steam supply flow rate at the user end is positive and large, then the proportional gain coefficient should be a larger value and the differential gain coefficient should be a larger value. reason: (1) The current hot water temperature error is positive, indicating that the real-time hot water temperature is much higher than the target hot water temperature and the system response is insufficient. At this time, a larger proportional gain coefficient should be used to improve the control strength and speed up the system response. (2) A negative high rate of change of hot water temperature error indicates that the real-time hot water temperature is decreasing at a relatively fast speed. At this time, a larger differential gain coefficient should be used to provide stronger predictive control damping and thus avoid overshoot. However, at this time, the current user-end steam supply flow is large and the rate of change of user-end steam supply flow is positive. That is, the user-end steam supply factor may affect the supply of heat exchange steam in the high-pressure heater. Moreover, the user-end steam supply flow is increasing at a relatively fast speed. Therefore, the rate of decrease of the real-time hot water temperature tends to be faster. Therefore, a larger differential gain coefficient is needed at this time to provide greater predictive control damping.

[0056] 2. If the current hot water temperature error is large positive, the hot water temperature error change rate is high negative, the current steam supply flow rate at the user end is small, and the steam supply flow rate at the user end is small positive, then the proportional gain coefficient and the differential gain coefficient should be large. reason: (1) The current hot water temperature error is positive, indicating that the real-time hot water temperature is much higher than the target hot water temperature and the system response is insufficient. At this time, a larger proportional gain coefficient should be used to improve the control strength and speed up the system response. (2) A negative high rate of change of hot water temperature error indicates that the real-time temperature of hot water is decreasing at a relatively fast speed. At this time, a larger value of differential gain coefficient should be used to provide stronger predictive control damping and thus avoid overshoot. At this time, the current user-end steam supply flow rate is small and the rate of change of user-end steam supply flow rate is positive, that is, the user-end steam supply factor will not affect the supply of heat exchange steam in the high-pressure heater (Note: because the amount of low-pressure steam that the turbine can provide is relatively sufficient). Therefore, at this time, a larger value of differential gain coefficient can still be used, and it is not necessary to consider the current user-end steam supply flow rate and the rate of change of user-end steam supply flow rate.

[0057] Specifically, to implement the above update logic, the membership function set and fuzzy inference rule set designed for the current hot water temperature error, the rate of change of the hot water temperature error, the current steam supply flow rate at the user end, and the rate of change of the steam supply flow rate at the user end (Note: the membership function set and fuzzy inference rule set are basic contents involved in fuzzy control, so they will not be discussed in detail here) can be designed according to actual needs. Details are not shown here; the following only explains the general process of fuzzy control: First, a membership function set needs to be set for the current hot water temperature error, the rate of change of hot water temperature error, the current steam supply flow rate at the user end, and the rate of change of steam supply flow rate at the user end. Each membership function set includes multiple membership functions, and each membership function corresponds to a fuzzy partitioning interval (i.e., the negative small interval of error, the positive large interval of error, the positive small interval of rate of change, the negative small interval of rate of change, etc.). Based on multiple membership functions, the membership values ​​of the current hot water temperature error, the rate of change of hot water temperature error, the current steam supply flow rate at the user end, and the rate of change of steam supply flow rate at the user end can be obtained in each fuzzy partitioning interval. Furthermore, a fuzzy inference rule set needs to be set up, which includes multiple fuzzy inference rules; Furthermore, after obtaining the membership information corresponding to the current hot water temperature error, the rate of change of hot water temperature error, the current steam supply flow rate at the user end, and the rate of change of steam supply flow rate at the user end, the rule membership value of each rule can be calculated by using the minimum value calculation method, but is not limited to. Finally, based on the rule membership values ​​of each rule and the defuzzification function (such as the center-weighted average method), the output values ​​corresponding to the proportional gain coefficient and the differential gain coefficient can be obtained.

[0058] Although the subject matter has been described using language specific to structural features and / or methodological logic, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are merely illustrative examples of implementing the claims.

Claims

1. A dual-turbine feedwater regeneration device adaptable to multiple operating conditions, characterized in that, It includes a first steam turbine, a second steam turbine, a first high-pressure heater, a second high-pressure heater, a third high-pressure heater, a fourth high-pressure heater, a boiler, a deaerator, a water source, and a control module; The first steam turbine includes a first high-pressure steam outlet, a first intermediate-pressure steam outlet, and a first low-pressure steam outlet; the second steam turbine includes a second high-pressure steam outlet, a second intermediate-pressure steam outlet, and a second low-pressure steam outlet. A first water supply pipeline, running from the water source to the boiler, connects the water source, deaerator, first high-pressure heater, second high-pressure heater, and boiler. A second water supply pipeline, also running from the water source to the boiler, connects the water source, deaerator, third high-pressure heater, fourth high-pressure heater, and boiler. The first high-pressure steam outlet is connected to the second high-pressure heater inlet and the fourth high-pressure heater inlet via a first steam supply pipeline and a second steam supply pipeline, respectively; the first medium-pressure steam outlet is connected to the first high-pressure heater inlet via a third steam supply pipeline; and the first low-pressure steam outlet is connected to the third high-pressure heater inlet via a fourth steam supply pipeline. The second high-pressure steam outlet is connected to the second high-pressure heater inlet and the fourth high-pressure heater inlet via a fifth and a sixth steam supply pipeline, respectively; the second medium-pressure steam outlet is connected to the third high-pressure heater inlet via a seventh steam supply pipeline; and the second low-pressure steam outlet is connected to the first high-pressure heater inlet via an eighth steam supply pipeline. The control module controls the on / off state of the third, fourth, fifth, sixth, seventh, and eighth steam pipelines based on the on / off status of the first and second steam turbines.

2. The dual-turbine feedwater regeneration device adapted to multiple operating conditions according to claim 1, characterized in that, Both the fourth and eighth steam supply pipelines are connected to the steam supply pipelines leading to the user end.

3. The dual-turbine feedwater regeneration device adapted to multiple operating conditions according to claim 2, characterized in that: A first regulating valve is installed on the pipeline connected to the steam inlet of the second high-pressure heater to control the flow rate of the steam fed into the second high-pressure heater. A second regulating valve is installed on the pipeline connected to the steam inlet of the fourth high-pressure heater to control the flow rate of the steam fed into the fourth high-pressure heater.

4. The dual-turbine feedwater regeneration device adapted to multiple operating conditions according to claim 3, characterized in that: A third regulating valve is installed on the third steam supply pipeline to control the flow rate of the steam supplied from the third steam supply pipeline to the first high-pressure heater; A fourth regulating valve is installed on the seventh steam supply pipeline to control the flow rate of the steam supplied from the seventh steam supply pipeline to the third high-pressure heater.

5. A dual-turbine feedwater regeneration device adapted to multiple operating conditions according to claim 4, characterized in that: A fifth regulating valve is installed on the fourth steam supply pipeline to control the flow rate of the steam supplied from the fourth steam supply pipeline to the third high-pressure heater; A sixth regulating valve is installed on the eighth steam supply pipeline to control the flow rate of the steam supplied from the eighth steam supply pipeline to the first high-pressure heater.

6. The dual-turbine feedwater regeneration device adapted to multiple operating conditions according to claim 1, characterized in that, A first drain line connects the second high-pressure heater to the first high-pressure heater, and a second drain line connects the first high-pressure heater to the deaerator. A first vapor-liquid two-phase drain is installed at the first drain line, and a first drain regulating valve is installed at the second drain line. A third drain line connects the fourth high-pressure heater to the third high-pressure heater, and a fourth drain line connects the third high-pressure heater to the deaerator. A second vapor-liquid two-phase drain is installed at the third drain line, and a second drain regulating valve is installed at the fourth drain line. The control module, in conjunction with the target water level and the real-time water level in the first high-pressure heater, calls the water level PID control model to control the opening degree of the first drainage regulating valve; The control module, in conjunction with the target water level and the real-time water level in the third high-pressure heater, calls the water level PID control model to control the opening degree of the second drainage regulating valve.

7. A dual-turbine feedwater regeneration device adaptable to multiple operating conditions according to claim 5, characterized in that, The control module controls the on / off state of the third, fourth, fifth, sixth, seventh, and eighth steam delivery pipelines based on the on / off states of the first and second steam turbines, including: When both the first and second steam turbines are in the start-up state, the first, second, third, fifth, sixth, and seventh steam delivery pipelines are controlled to be in the conducting state, and the fourth and eighth steam delivery pipelines are controlled to be in the cut-off state. When the first steam turbine is in shutdown state and the second steam turbine is in startup state, the fifth, sixth, seventh, and eighth steam supply pipelines are controlled to be in the conducting state, and the first, second, third, and fourth steam supply pipelines are controlled to be in the shut-off state. When the second steam turbine is shut down and the first steam turbine is running, the first, second, third, and fourth steam delivery pipelines are controlled to be in the on state, and the fifth, sixth, seventh, and eighth steam delivery pipelines are controlled to be in the off state.

8. A dual-turbine feedwater regeneration device adapted to multiple operating conditions according to claim 7, characterized in that, It also includes a parameter acquisition module; The parameter acquisition module acquires the target temperature of hot water and the real-time temperature of hot water inside the boiler. The control module, based on the on / off status of the first and second steam turbines, calls the corresponding temperature PID control model and combines the target hot water temperature and the real-time hot water temperature to control the opening degree of the regulating valves on each steam pipeline that is currently in the conducting state.

9. A dual-turbine feedwater regeneration device adapted to multiple operating conditions according to claim 8, characterized in that: The control module, when both the first and second steam turbines are in the start-up state, combines the target hot water temperature and the real-time hot water temperature, and calls the first temperature PID control model to control the opening degree of the first and second regulating valves, and calls the second temperature PID control model to control the opening degree of the third and fourth regulating valves. The control module, when the first steam turbine is in a shutdown state and the second steam turbine is in a startup state, combines the target parameters of hot water and the real-time parameters of hot water, and calls the third temperature PID control model to control the opening of the first regulating valve and the second regulating valve, calls the second temperature PID control model to control the opening of the fourth regulating valve, and calls the fourth temperature PID control model to control the opening of the sixth regulating valve. The control module, when the second steam turbine is in a stopped state and the first steam turbine is in a started state, combines the target parameters of hot water and the real-time parameters of hot water, and calls the third temperature PID control model to control the opening degree of the first regulating valve and the second regulating valve, calls the second temperature PID control model to control the opening degree of the third regulating valve, and calls the fourth temperature PID control model to control the opening degree of the fifth regulating valve.

10. A dual-turbine feedwater regeneration device adapted to multiple operating conditions according to claim 9, characterized in that, It also includes a parameter update module; the parameter update module includes a first parameter acquisition unit, a second parameter acquisition unit, and a parameter update unit; The first parameter acquisition unit acquires the current hot water temperature error and the rate of change of the hot water temperature error. The second parameter acquisition unit acquires the current steam supply flow rate at the user end and the rate of change of the steam supply flow rate at the user end. The parameter update unit updates the model parameters of the fourth PID control model based on the fuzzy control algorithm when the first or second steam turbine is out of service, taking into account the current hot water temperature error, the rate of change of hot water temperature error, the current steam supply flow rate at the user end, and the rate of change of steam supply flow rate at the user end.

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