Feed water temperature control system and method capable of adapting to deep peak regulation through elastic heat regeneration

Abstract

The invention discloses a feed water temperature control system and method for elastic heat regeneration to adapt to deep peak regulation. The feed water temperature control system comprises a data acquisition module, an operation state judgment module and a water temperature regulation module. The data acquisition module is responsible for acquiring operation data of the coal-fired unit in real time; the running state judgment module judges the running state of the unit according to the data; the water temperature adjusting module is used for controlling the feed water temperature by adjusting the opening degree of a zero-section steam extraction adjusting valve according to the judgment result; the problem that due to zero-number high-pressure constant-pressure operation under the deep peak regulation load, the feed water temperature is greatly increased, and consequently the operation stability and safety of an economizer and a water cooling wall are possibly threatened is solved, the operation requirement of a coal-fired unit in the deep peak regulation process is met, and accurate control over the feed water temperature is ensured; therefore, the operation efficiency and stability of the unit are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of coal-fired power generation equipment, and relates to a feed water temperature control system and method capable of elastically recovering heat and adapting to deep peak regulation. Background Art

[0002] With the increasing global awareness of environmental protection and the transformation of energy structure, the installed capacity of new energy such as wind power and photovoltaics in the power system continues to expand, becoming an important force in promoting green energy development. However, new energy power generation has the characteristics of intermittency and uncertainty, and its large-scale grid connection has brought new challenges to the stable operation of the power system, especially in terms of power supply and demand balance and grid dispatching. In order to effectively promote the consumption of new energy and improve the overall energy utilization efficiency, the role of traditional coal-fired units in the power system is undergoing profound changes, gradually changing from a simple power supply to a comprehensive power supply with both power supply and power regulation functions. This transformation requires coal-fired units to have stronger flexibility and adjustment capabilities to better adapt to the volatility and uncertainty of new energy power generation. Among them, deep peak regulation has become one of the important means for coal-fired units to participate in grid regulation.

[0003] In the process of deep peak regulation of coal-fired units, the operating efficiency and stability of the steam turbine are crucial. Although the traditional heat recovery system has improved the thermal efficiency of the unit to a certain extent, its adjustment ability and adaptability are limited under low-load operating conditions. For this reason, the steam turbine elastic heat recovery system came into being. As an adjustable feedwater heat recovery system, it can effectively increase the feedwater temperature when the unit is running at low load by adding zero-stage adjustable extraction steam and zero-high pressure heating, thereby increasing the inlet flue gas temperature of the denitrification device, which is of great significance for improving the investment rate and denitrification efficiency of the denitrification device under low load. This technological innovation not only helps to reduce nitrogen oxide emissions when coal-fired units are operating at low load, but also improves the environmental protection performance and economic benefits of the unit.

[0004] However, in actual applications, the operation of the turbine elastic heat recovery system under deep peak load also faces some challenges. Especially when the unit load is less than 40%, the turbine is usually set to constant pressure operation, and the zero-pressure high-pressure heater is also set to constant pressure operation. This mode of operation will cause the feed water temperature to increase significantly under deep peak load, which may pose a threat to the operating stability and safety of the economizer and water-cooled wall. Especially in the critical state stage before the dry-wet state conversion under deep peak load, due to the drastic change in feed water temperature, the thermal stress of the economizer and water-cooled wall may increase, increasing the risk of equipment damage and affecting the long-term safe operation of the unit. Summary of the invention

[0005] The purpose of the present invention is to solve the technical problem in the prior art that the zero-level high-pressure boiler operates at a constant pressure under deep peak-shaving load of the unit, resulting in a significant increase in feed water temperature, which may pose a threat to the operating stability and safety of the economizer and water-cooled wall, and to provide a feed water temperature control system and method with elastic heat recovery that is adaptable to deep peak-shaving.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The first aspect of the present invention provides a feed water temperature control system with elastic heat recovery and deep peak regulation, comprising: Data acquisition module, used to collect real-time operation data of coal-fired units; An operation status judgment module is used to determine the operation status of the coal-fired unit according to the real-time operation data of the coal-fired unit; The water temperature regulation module is used to adjust the opening of the zero-stage steam extraction regulating valve based on the operating status of the coal-fired unit, thereby controlling the feed water temperature under the unit's deep peak load regulation.

[0007] Furthermore, the water supply temperature control system of the present invention further comprises: The early warning module is used to issue an alarm for abnormal operation data of the unit based on the real-time operation data of the coal-fired unit.

[0008] A second aspect of the present invention provides a feed water temperature control method for elastic heat recovery and deep peak regulation, comprising the following steps: Collect real-time operation data of coal-fired units; According to the real-time operation data of the coal-fired unit, the operating status of the coal-fired unit is determined, and the opening of the zero-stage steam extraction regulating valve is adjusted to control the feed water temperature under the unit's deep peak load.

[0009] Furthermore, the real-time operating data include unit load, water-cooled wall temperature and wall temperature rise rate, economizer outlet feed water pressure, economizer outlet feed water temperature, economizer inlet water temperature, No. 0 high-pressure heater outlet water temperature, No. 0 high-pressure steam inlet pressure and zero-stage steam extraction regulating valve opening.

[0010] Furthermore, according to the real-time operation data of the coal-fired unit, the operation status of the coal-fired unit is determined, and the opening of the zero-stage steam extraction regulating valve is adjusted to control the feed water temperature, specifically: Based on the unit load, determine the operating status of the coal-fired unit and obtain the feed water subcooling degree at the economizer outlet; Based on the subcooling of the feed water at the economizer outlet, adjust the opening of the zero-stage extraction steam regulating valve to adjust the outlet water temperature of the zero-stage high-pressure heater and the inlet temperature of the economizer.

[0011] Further, the operating state of the coal-fired unit is determined based on the size of the unit load, and the feed water subcooling degree at the economizer outlet is obtained, specifically: When the unit load is greater than 40% of the rated load, the pressure after the zero-stage extraction steam regulating valve operates according to the relationship curve between the designed unit load and the zero-stage high-pressure steam inlet pressure; When the unit load is less than or equal to 40% of the rated load, the economizer outlet feed water subcooling is calculated based on the economizer outlet feed water pressure and economizer outlet feed water temperature.

[0012] Furthermore, based on the feed water subcooling degree at the economizer outlet, the opening of the zero-stage extraction valve is adjusted to adjust the outlet water temperature of the zero-stage high-pressure heater and the economizer inlet temperature, specifically: When the economizer outlet water subcooling degree is less than the first subcooling degree, the economizer outlet water low subcooling degree alarm is activated; When the economizer outlet water subcooling is less than the second subcooling, gradually reduce the opening of the zero-stage steam extraction regulating valve to reduce the zero-stage high-pressure heater outlet water temperature and the economizer inlet temperature.

[0013] Further, when the opening of the zero-stage steam extraction regulating valve is reduced to 0 and the economizer outlet water subcooling is less than the second subcooling, the boiler operation state is switched, specifically: Monitor the water-cooled wall temperature and abnormal wall temperature rise rate, and prepare for the start-up of the boiler water circulation pump; When the wall temperature and wall temperature rise rate of any water-cooled wall tube alarm abnormally, the separator outlet superheat is too low, the separator water level reaches the circulation pump start-up condition, or the feed water flow rate drops to the minimum flow rate of the water-cooled wall, the boiler water circulation pump is started and the boiler operation state changes from dry state to wet state.

[0014] Furthermore, it also includes: Based on the boiler operating status after switching, calculate the economizer outlet water subcooling, adjust the opening of the zero-stage steam extraction valve, and adjust the zero-stage high-pressure heater outlet water temperature and economizer inlet temperature.

[0015] Furthermore, the opening degree of the zero-stage steam extraction regulating valve is specifically adjusted as follows: Based on the subcooling of the feed water at the economizer outlet, the opening of the zero-stage steam extraction regulating valve is increased to increase the outlet water temperature of the zero-stage high-pressure heater and the inlet temperature of the economizer.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a feedwater temperature control method for adapting to deep peak regulation with elastic heat recovery. By real-time collection of various operating data of coal-fired units, including unit load, water-cooled wall temperature and heating rate, economizer inlet and outlet water temperature and pressure, zero high-pressure heater outlet water temperature, zero high-pressure heater inlet steam pressure and zero-stage extraction steam regulating valve opening, etc., a comprehensive and accurate information basis is provided for subsequent intelligent analysis. Based on the analysis of real-time data, the unit operation status can be quickly judged, providing a timely and reliable basis for the control of feedwater temperature; according to the change of unit load, the opening of the zero-stage extraction steam regulating valve is intelligently adjusted to optimize the feedwater temperature, thereby ensuring the stable operation of the coal-fired unit under different loads. When the unit load is high, it operates according to the design relationship curve to ensure efficient and stable heat exchange; when the unit load is reduced to below 40% of the rated load, the zero-stage extraction steam regulating valve is accurately adjusted by calculating the feedwater subcooling degree of the economizer outlet to maintain the appropriate level of feedwater temperature. By precisely adjusting the opening of the zero-stage extraction regulating valve, the feed water temperature can be strictly controlled, thereby protecting the operating stability and safety of the economizer and water-cooled wall. When the economizer outlet water subcooling is lower than the set threshold, the alarm is activated in time and corresponding adjustment measures are taken to avoid damage to the equipment due to overcooling. In extreme cases, when the zero-stage extraction regulating valve cannot be further adjusted and the economizer outlet water subcooling is still too low, this method can intelligently monitor key parameters such as the wall temperature and heating rate of the water-cooled wall, and prepare to start the boiler water circulation pump; once the switching conditions are met, the boiler is immediately switched from dry operation to wet operation to ensure the continuous and stable operation of the unit; by precisely controlling the feed water temperature, this method can optimize the thermal efficiency of the coal-fired unit and reduce energy waste; after the boiler operating state is switched, the zero-stage extraction regulating valve continues to be adjusted according to the new operating state to further improve thermal efficiency and reduce energy consumption.

[0017] The invention discloses a feed water temperature control system with elastic heat recovery and deep peak regulation. The data acquisition module can collect various operation data of the coal-fired unit in real time and accurately, including key parameters such as unit load, water temperature, pressure, etc., providing a solid foundation for subsequent analysis and control; through accurate analysis of real-time data, the system can quickly capture subtle changes in the operation state of the unit, providing timely and reliable basis for water temperature regulation; the operation state judgment module can judge the operation state of the coal-fired unit according to real-time operation data, including key indicators such as load level and thermal efficiency; the system can adopt corresponding water temperature regulation strategies according to different operation states of the unit, so as to ensure stable operation and efficient output of the unit; the water temperature regulation module realizes precise control of the feed water temperature by adjusting the opening of the zero-stage extraction steam regulating valve; this precise regulation mechanism can ensure that the feed water temperature of the unit is always kept within the optimal range under different loads and working conditions, thereby improving the thermal efficiency and operation stability of the unit. The early warning module can monitor the operation data of the coal-fired unit in real time, and once abnormal data is found, the alarm mechanism is immediately triggered; this early warning mechanism can timely discover and deal with potential problems in the operation of the unit, avoiding the expansion of faults or causing more serious consequences. At the same time, it can also provide timely fault information to operation and maintenance personnel, allowing them to quickly locate and solve problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 This is a block diagram of a water supply temperature control system with elastic heat recovery and deep peak regulation according to the present invention; Figure 2 This is a block diagram of the feed water temperature control method for elastic heat recovery to adapt to deep peak regulation of the present invention.

[0020] Among them: 101-data acquisition module; 102-operation status judgment module; 103-water temperature adjustment module. DETAILED DESCRIPTION In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention described and marked in the drawings here can be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0023] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0024] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0025] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings: See also Figure 1 The present invention discloses a water supply temperature control system with elastic heat recovery and deep peak regulation, comprising: The data acquisition module 101 is used to collect real-time operation data of the coal-fired unit; the data acquisition module is responsible for real-time collection of various operation data of the coal-fired unit, including but not limited to unit load, water-cooled wall temperature and wall temperature rise rate, economizer outlet feed water pressure, economizer outlet feed water temperature, economizer inlet water temperature, No. 0 high-pressure heater outlet water temperature, No. 0 high-pressure heater inlet steam pressure and zero-stage extraction steam regulating valve opening. These data are obtained in real time through sensors and monitoring equipment. The operation status judgment module 102 is used to determine the operation status of the coal-fired unit according to the real-time operation data of the coal-fired unit; this module receives the real-time operation data transmitted by the data acquisition module, performs preprocessing and analysis; judges the operation status of the unit, and identifies whether the unit is in a normal, abnormal or deep peak-shaving state. At the same time, this module also sends the processed data to the water temperature adjustment module and the early warning module to support subsequent decision-making and control.

[0027] The water temperature regulating module 103 is used to adjust the opening of the zero-stage extraction steam regulating valve based on the operating state of the coal-fired unit, thereby controlling the feed water temperature; the water temperature regulating module automatically adjusts the opening of the zero-stage extraction steam regulating valve according to the judgment result of the operating state judgment module, thereby controlling the steam inlet pressure of the zero-stage high-pressure heater, and then realizing accurate adjustment of the feed water temperature. By adjusting the feed water temperature, the operating stability and safety of the economizer and water-cooled wall can be ensured, and equipment damage or efficiency reduction caused by excessively high or low temperatures can be avoided.

[0028] An embodiment of the present invention provides a feed water temperature control system with elastic heat recovery and deep peak regulation, and also includes an early warning module for alarming abnormal operation data of the unit based on the real-time operation data of the coal-fired unit. The early warning module monitors the various monitoring parameters of the coal-fired unit in real time. When the parameters exceed the normal range, the module will automatically trigger the alarm mechanism to remind the operator to pay attention to the operation status of the unit. When the unit is in an abnormal state, the early warning module will also trigger equipment protection actions, such as closing relevant valves, starting backup equipment, etc., to ensure the safe operation of the unit.

[0029] See also Figure 2 An embodiment of the present invention provides a feed water temperature control method for elastic heat recovery and deep peak regulation, comprising the following steps: S1, collect real-time operation data of coal-fired units; through sensors and data acquisition systems, collect various operation data of coal-fired units in real time, including but not limited to unit load, economizer outlet feed water temperature, economizer outlet feed water pressure, zero-stage extraction steam regulating valve opening, etc. These data will serve as the basis for subsequent analysis and control. S2, according to the real-time operation data of the coal-fired unit, determines the operating status of the coal-fired unit, adjusts the opening of the zero-stage steam extraction regulating valve, and thus controls the feed water temperature.

[0030] According to the real-time operation data collected, the preset algorithm or model is used to analyze and judge the operation status of the coal-fired unit, including key indicators such as load level and thermal efficiency. According to the determined operation status of the coal-fired unit, the opening of the zero-stage steam extraction valve is automatically adjusted through the control system to control the feed water temperature.

[0031] An embodiment of the present invention provides a feed water temperature control method for elastic heat recovery and deep peak regulation, comprising the following steps: S1, collects the operation data of the coal-fired unit, including unit load, water wall temperature and wall temperature rise rate, economizer outlet feed water pressure, economizer outlet feed water temperature, economizer inlet water temperature, No. 0 high pressure heater outlet water temperature, No. 0 high pressure heater inlet steam pressure and zero stage extraction steam regulating valve opening. These data are obtained in real time through sensors and monitoring equipment, providing a basis for subsequent analysis and control.

[0032] S2, according to the real-time operation data of the coal-fired unit, determines the operating status of the coal-fired unit, adjusts the opening of the zero-stage steam extraction regulating valve, and thus controls the feed water temperature.

[0033] S201, based on the size of the unit load, determine the operating status of the coal-fired unit. When the unit load is greater than 40% of the rated load, the pressure after the zero-stage extraction steam regulating valve operates according to the relationship curve between the design unit load and the zero-stage high-pressure inlet steam pressure; when the unit load is less than or equal to 40% of the rated load, the economizer outlet feed water subcooling is calculated based on the economizer outlet feed water pressure and economizer outlet feed water temperature.

[0034] S202, according to the outlet feed water subcooling of the economizer, adjust the opening of the zero-stage steam extraction regulating valve. When the outlet water subcooling of the economizer is less than the set first subcooling threshold, the low outlet water subcooling alarm of the economizer is activated; when the outlet water subcooling of the economizer is less than the set second subcooling threshold (less than the first subcooling threshold), the opening of the zero-stage steam extraction regulating valve is gradually reduced, thereby reducing the outlet water temperature of the zero-stage high-pressure heater and the inlet temperature of the economizer, so as to protect the operating stability of the economizer and the water-cooled wall.

[0035] S3, when the opening of the zero-stage steam extraction regulating valve is reduced to 0 and the economizer outlet water subcooling is still less than the second subcooling threshold, the boiler operation state is switched. First, monitor the wall temperature and wall temperature rise rate of the water-cooled wall for abnormalities, and prepare for the start of the boiler water circulation pump. When the wall temperature and wall temperature rise rate of any water-cooled wall tube alarm abnormally, the separator outlet superheat is too low, the separator water level reaches the circulation pump start-up condition, or the feed water flow rate drops to the minimum flow of the water-cooled wall, start the boiler water circulation pump to switch the boiler from dry operation to wet operation.

[0036] S4, after the boiler operation state is switched, recalculate the economizer outlet water subcooling, and adjust the opening of the zero-stage steam extraction regulating valve according to the new subcooling value. At this time, by increasing the opening of the zero-stage steam extraction regulating valve, the zero-stage high-pressure heater outlet water temperature and the economizer inlet temperature are increased to optimize the unit's thermal efficiency and ensure that the feed water temperature meets the needs of deep peak regulation.

[0037] Through the feed water temperature control method of the embodiment of elastic heat recovery adapted to deep peak regulation, the feed water temperature of the coal-fired unit during the deep peak regulation process is accurately controlled, effectively improving the operating stability and safety of the unit. At the same time, the method can intelligently adjust the opening of the zero-stage steam extraction valve according to the changes in the unit load and operating status, optimize the thermal efficiency of the unit, and reduce energy consumption and emissions. In addition, the early warning and switching mechanism of the method can also promptly detect and handle abnormal conditions in the operation of the unit, avoiding potential safety risks.

[0038] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A water supply temperature control system with elastic heat recovery and deep peak regulation, characterized in that: include: Data acquisition module, used to collect real-time operation data of coal-fired units; An operation status judgment module is used to determine the operation status of the coal-fired unit according to the real-time operation data of the coal-fired unit; The water temperature regulation module is used to adjust the opening of the zero-stage steam extraction regulating valve based on the operating status of the coal-fired unit, thereby controlling the feed water temperature under the unit's deep peak load regulation.

2. The water supply temperature control system with elastic heat recovery and deep peak regulation according to claim 1 is characterized in that: Also includes: The early warning module is used to issue an alarm for abnormal operation data of the unit based on the real-time operation data of the coal-fired unit.

3. A water supply temperature control method with elastic heat recovery and deep peak regulation, characterized in that: The following steps are involved: Collect real-time operation data of coal-fired units; According to the real-time operation data of the coal-fired unit, the operating status of the coal-fired unit is determined, and the opening of the zero-stage steam extraction regulating valve is adjusted to control the feed water temperature under the unit's deep peak load.

4. The water supply temperature control method for elastic heat recovery and deep peak regulation according to claim 3 is characterized in that: The real-time operating data include unit load, water-cooled wall temperature and wall temperature rise rate, economizer outlet feed water pressure, economizer outlet feed water temperature, economizer inlet water temperature, No. 0 high-pressure heater outlet water temperature, No. 0 high-pressure heater inlet steam pressure and zero-stage steam extraction regulating valve opening.

5. The feed water temperature control method for elastic heat recovery and deep peak regulation according to claim 4 is characterized in that: According to the real-time operation data of the coal-fired unit, the operation status of the coal-fired unit is determined, and the opening of the zero-stage steam extraction regulating valve is adjusted to control the feed water temperature. Specifically: Based on the unit load, determine the operating status of the coal-fired unit and obtain the feed water subcooling degree at the economizer outlet; Based on the subcooling of the feed water at the economizer outlet, adjust the opening of the zero-stage extraction steam regulating valve to adjust the outlet water temperature of the zero-stage high-pressure heater and the inlet temperature of the economizer.

6. The feed water temperature control method for elastic heat recovery and deep peak regulation according to claim 5 is characterized in that: The operating state of the coal-fired unit is determined based on the size of the unit load, and the feed water subcooling degree at the economizer outlet is obtained, which is specifically: When the unit load is greater than 40% of the rated load, the pressure after the zero-stage extraction steam regulating valve operates according to the relationship curve between the designed unit load and the zero-stage high-pressure steam inlet pressure; When the unit load is less than or equal to 40% of the rated load, the economizer outlet feed water subcooling is calculated based on the economizer outlet feed water pressure and economizer outlet feed water temperature.

7. The feed water temperature control method for elastic heat recovery and deep peak regulation according to claim 5 is characterized in that: Based on the feed water subcooling at the economizer outlet, the opening of the zero-stage extraction valve is adjusted to adjust the outlet water temperature of the zero-stage high-pressure heater and the economizer inlet temperature, specifically: When the economizer outlet water subcooling degree is less than the first subcooling degree, the economizer outlet water low subcooling degree alarm is activated; When the economizer outlet water subcooling is less than the second subcooling, gradually reduce the opening of the zero-stage steam extraction regulating valve to reduce the zero-stage high-pressure heater outlet water temperature and the economizer inlet temperature.

8. The water supply temperature control method for elastic heat recovery and deep peak regulation according to claim 7 is characterized in that: When the opening of the zero-stage steam extraction regulating valve is reduced to 0 and the economizer outlet water subcooling is less than the second subcooling, the boiler operation state is switched, specifically: Monitor the water-cooled wall temperature and abnormal wall temperature rise rate, and prepare for the start-up of the boiler water circulation pump; When the wall temperature and wall temperature rise rate of any water-cooled wall tube alarm abnormally, the separator outlet superheat is too low, the separator water level reaches the circulation pump start-up condition, or the feed water flow rate drops to the minimum flow rate of the water-cooled wall, the boiler water circulation pump is started and the boiler operation state changes from dry state to wet state.

9. The water supply temperature control method for elastic heat recovery and deep peak regulation according to claim 8 is characterized in that: Also includes: Based on the boiler operating status after switching, calculate the economizer outlet water subcooling, adjust the opening of the zero-stage steam extraction valve, and adjust the zero-stage high-pressure heater outlet water temperature and economizer inlet temperature.

10. The water supply temperature control method for elastic heat recovery and deep peak regulation according to claim 9 is characterized in that: The opening degree of the zero-stage steam extraction regulating valve is specifically adjusted as follows: Based on the subcooling of the feed water at the economizer outlet, the opening of the zero-stage steam extraction regulating valve is increased to increase the outlet water temperature of the zero-stage high-pressure heater and the inlet temperature of the economizer.

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