Water supply method and system for coal-fired power generating unit under low-load working condition

Abstract

The invention discloses a water supply method and system for a coal-fired power generation unit under a low-load working condition, and the method comprises the steps: collecting the operation state information of the coal-fired power generation unit in real time, judging whether the unit is in the low-load working condition, and starting a low-load water supply regulation mode if the current actual load is smaller than or equal to 40% of rated load; extracting main steam in a main steam pipeline as ejection steam, extracting a section of regenerative extraction steam with the highest pressure of a steam turbine as ejected steam, and mixing and boosting the ejection steam and the ejected steam to obtain mixed steam; the fed water is secondarily heated based on the mixed steam, and the fluctuation range of the water level of the boiler is controlled within + / -50 mm; and monitoring the load change of the unit in real time, and when the actual load of the unit is increased to more than 40% of the rated load, closing the low-load water supply regulation and control mode, and switching to the conventional water supply mode.

Description

Technical Field

[0001] This invention relates to the field of coal-fired boiler operation control technology, specifically to a water supply method and system for coal-fired power generating units under low-load conditions. Background Technology

[0002] With the rapid development of new energy power generation technologies, coal-fired power generating units have gradually taken on the important tasks of peak shaving and frequency regulation, and it has become the norm for them to frequently operate under low-load conditions, often below 40% of their rated load. However, the existing water supply systems and methods for coal-fired power generating units are mainly designed for rated load or higher load conditions, and there are many technical bottlenecks under low-load conditions, which seriously affect the safe and stable operation of the units, as well as their economic efficiency and environmental friendliness.

[0003] Specifically, under low-load conditions, the amount of steam extracted from the turbine for reheating is significantly reduced, and the extraction pressure drops substantially. This results in insufficient heating capacity of the high-pressure heater, preventing the feedwater temperature from reaching design requirements. Consequently, the economizer outlet flue gas temperature becomes excessively low, which not only easily leads to economizer corrosion and ash accumulation but also affects the catalyst activity of the boiler tail-end denitrification system, causing a decrease in denitrification efficiency and failing to meet environmental emission requirements. Simultaneously, the feedwater flow demand decreases drastically under low load conditions, making the feedwater pump prone to deviating from its high-efficiency operating range and experiencing cavitation due to insufficient inlet pressure. This results in large fluctuations in feedwater flow, making it difficult to stably control the boiler water level and increasing the operational risks of the unit.

[0004] Currently, most solutions to the aforementioned problems are partial adjustments, such as simply increasing the minimum flow rate of the feedwater pump or adding auxiliary heating devices. These solutions suffer from drawbacks such as significant heat loss, poor equipment adaptability, insufficient control precision, high system complexity, and high costs. They cannot fundamentally solve the comprehensive problems of insufficient feedwater temperature, unstable flow, low equipment operating efficiency, and difficulty in meeting environmental standards under low-load conditions. Therefore, developing a feedwater method and system that is highly adaptable, precisely controlled, energy-saving, environmentally friendly, and can ensure the safe and stable operation of the unit under low load has become an urgent technical challenge in the field of peak-shaving operation of coal-fired power generating units. Summary of the Invention

[0005] The purpose of this invention is to provide a water supply method and system for coal-fired power generating units under low-load conditions to solve the problems mentioned in the background art.

[0006] To achieve the above-mentioned objectives, the first technical solution adopted by this invention is: a water supply method for a coal-fired power generating unit under low-load conditions, comprising: S1: Real-time collection of operating status information of coal-fired power generation units to determine whether the unit is under low load conditions. If the current actual load is ≤40% of the rated load, the low load water supply control mode is activated. S2, extract the main steam in the main steam pipeline as the ejector steam, extract the regenerated steam with the highest pressure in the turbine section as the ejected steam, mix the ejector steam and the ejected steam and pressurize them to obtain mixed steam; S3, after the mixed steam is regulated by the mixed steam valve, it is sent to the steam side of the low-load feedwater heater. At the same time, the feedwater that has been preheated by the high-pressure heater is sent to the water side of the low-load feedwater heater. The mixed steam is used to reheat the feedwater, and the feedwater outlet temperature of the low-load feedwater heater is controlled to be no less than 150℃. S4, after the condensate generated by the low-load feedwater heater is regulated by the condensate valve, is introduced into the steam side of the high-pressure heater for recycling; real-time monitoring of feedwater temperature, flow rate and boiler water level parameters, by adjusting the opening of the steam valve, the ejected steam valve, the mixing steam valve and the condensate valve, combined with the speed regulation of the feedwater pump, to maintain stable feedwater flow and control the boiler water level fluctuation range within ±50mm. S5 monitors unit load changes in real time. When the actual unit load rises to more than 40% of the rated load, it shuts down the low-load water supply control mode and switches to the normal water supply mode.

[0007] Furthermore, the operating status information includes the rated load of the coal-fired power generation unit, the current actual load, the main steam pressure and flow rate, the turbine regenerative extraction steam pressure and flow rate, the feedwater temperature and flow rate, the boiler water level, and the economizer outlet flue gas temperature parameters.

[0008] Furthermore, in step S1, the parameter acquisition frequency is 1-5Hz, and the response time for operating condition identification is ≤10s; low-load operating conditions also include scenarios where the unit load fluctuates frequently and the fluctuation amplitude is ≥5% of the rated load / minute.

[0009] Furthermore, in step S3, the low-load feedwater heater adopts a shell-and-tube structure, with feedwater flowing in the tube side and mixed steam flowing in the shell side, and the heat exchange temperature difference is controlled at 15-25℃; when the feedwater temperature at the outlet of the low-load feedwater heater is lower than the set value, the mixed steam flow rate is increased, the ejector ratio of the jet heat pump is adjusted, and the mixed steam pressure and temperature are adjusted accordingly.

[0010] Furthermore, in step S4, the adjustment of the feedwater flow rate adopts a three-impulse control and variable parameter adjustment mode, with the boiler water level as the main control signal, the steam flow rate as the feedforward signal, and the feedwater flow rate as the feedback signal. The PID parameters are dynamically adjusted according to the load changes, and the feedwater pump adopts variable frequency speed control with a speed range of 30%-100% of the rated speed.

[0011] Furthermore, in step S5, the operating condition switching process adopts gradual control, with the mixed steam flow rate and feedwater pump speed gradually adjusted, and the switching time controlled within 30-60 seconds to avoid system fluctuations caused by sudden load changes.

[0012] Furthermore, in step S3, the outlet water temperature of the low-load water heater is monitored redundantly by setting two independent temperature sensors. When the difference between the measurements of the two sensors is ≥5℃, an abnormal temperature alarm is issued.

[0013] Furthermore, in step S4, the control standards for water quality are: water hardness ≤2μmol / L, dissolved oxygen ≤15μg / L, iron content ≤20μg / L, and copper content ≤5μg / L. The water quality is monitored in real time by an online water quality monitoring module. When the water quality exceeds the standards, the controller automatically starts the water purification device for treatment.

[0014] To achieve the above-mentioned objectives, the second technical solution adopted by the present invention is: a water supply system for a coal-fired power generation unit under low-load conditions, comprising a processor, a memory, and at least one program, wherein the program is stored in the memory and configured to be executed by the processor, and the program includes instructions for executing a water supply method for a coal-fired power generation unit under low-load conditions.

[0015] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: 1. Effectively solves the core pain point of low-load feedwater and ensures safe and stable operation of the unit: Through optimized matching of steam source and graded heating regulation, the feedwater temperature at the outlet of the low-load feedwater heater is controlled above 150℃, avoiding corrosion and ash accumulation caused by excessively low flue gas temperature at the economizer outlet, while ensuring stable and efficient operation of the denitrification system to meet environmental emission requirements; combined with dynamic flow control and variable frequency speed regulation of feedwater pump, the boiler water level fluctuation is controlled within ±50mm, avoiding feedwater pump cavitation, solving the problem of unstable feedwater flow, and adapting to low-load and frequent load fluctuation conditions.

[0016] 2. Improve energy efficiency and reduce operating costs: By mixing and pressurizing the main steam and regenerated extraction steam through a jet heat pump, the waste heat of the regenerated extraction steam is fully recovered and utilized, reducing the consumption of main steam; at the same time, the condensate generated by the low-load feedwater heater is recovered and introduced into the high-pressure heater for recycling, minimizing heat loss and reducing unit energy consumption; the feedwater pump adopts variable frequency speed control to adapt to low-load flow demand, avoid ineffective energy consumption, and further improve the system economy.

[0017] 3. Precise control, strong adaptability, and convenient operation: The control system collects multi-dimensional operating parameters in real time, with a working condition identification response time of ≤10s. It can quickly switch between low-load control mode and normal mode, adapting to scenarios with frequent fluctuations in unit load. Each steam valve and condensate valve adopts stepless adjustment, combined with feedforward + feedback composite control logic, resulting in high control accuracy. It can dynamically optimize control parameters according to changes in unit load, without requiring a lot of manual intervention, thus reducing operation and maintenance costs.

[0018] 4. Simple structure, low modification difficulty, and strong practicality: This system is based on the optimization and modification of the existing water supply system of coal-fired power generating units. It does not require the addition of complex auxiliary equipment, has strong compatibility, short modification cycle, and low cost. The method and steps are clear and the connection with the existing unit operation process is smooth. It can be directly applied to the low-load water supply control of various coal-fired power generating units and has broad prospects for promotion and application.

[0019] 5. High system reliability and convenient operation and maintenance: By setting auxiliary components such as exhaust valves, pressure gauges, and thermometers, the system can monitor the operating status in real time, promptly discharge non-condensable gases, and provide early warning of abnormal parameters; the alarm module can issue audible and visual alarms and initiate emergency control when parameters exceed limits, reducing the risk of unit operation; each piece of equipment has a mature structure and low operation and maintenance difficulty, which can effectively reduce the workload of operation and maintenance personnel. Attached Figure Description

[0020] Figure 1 The flowchart of the water supply method for a coal-fired power generation unit under low load conditions provided in the embodiment of the present invention is shown. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0022] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. 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 system that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or systems.

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] like Figure 1 As shown, this embodiment of the invention provides a water supply method for a coal-fired power generation unit under low-load conditions, comprising: S1: Real-time collection of operating status information of coal-fired power generation units to determine whether the unit is under low load conditions. If the current actual load is ≤40% of the rated load, the low load water supply control mode is activated. S2, extract the main steam in the main steam pipeline as the ejector steam, extract the regenerated steam with the highest pressure in the turbine section as the ejected steam, mix the ejector steam and the ejected steam and pressurize them to obtain mixed steam; It should be noted that the main steam injection flow rate is steplessly regulated by the steam valve with an adjustment accuracy of ±0.5t / h; the injected steam flow rate is steplessly regulated by the injected steam valve to ensure that the pressure fluctuation of the mixed steam is ≤0.2MPa and the temperature fluctuation is ≤10℃.

[0025] The steam-water separation process uses a cyclone steam-water separator with a separation efficiency of ≥99.5%, ensuring that the dryness of the steam entering the jet heat pump is ≥99%.

[0026] Before entering the jet heat pump, both the main steam and the regenerated extraction steam undergo steam-water separation treatment to remove liquid water droplets entrained in the steam, thus preventing the water droplets from eroding the internal components of the jet heat pump.

[0027] S3, after the mixed steam is regulated by the mixed steam valve, it is sent to the steam side of the low-load feedwater heater. At the same time, the feedwater that has been preheated by the high-pressure heater is sent to the water side of the low-load feedwater heater. The mixed steam is used to reheat the feedwater, and the feedwater outlet temperature of the low-load feedwater heater is controlled to be no less than 150℃. It should be noted that the feedwater flow rate of the low-load feedwater heater should be controlled at 1.0-2.0 m / s to avoid a decrease in heat exchange efficiency due to excessively low flow rate, while also preventing pipe wear caused by excessively high flow rate.

[0028] The heat exchange area of ​​the low-load feedwater heater is designed based on the unit's maximum low-load feedwater flow rate, with a heat exchange area redundancy of ≥15% to ensure sufficient heat exchange capacity.

[0029] S4, after the condensate generated by the low-load feedwater heater is regulated by the condensate valve, is introduced into the steam side of the high-pressure heater for recycling; real-time monitoring of feedwater temperature, flow rate and boiler water level parameters, by adjusting the opening of the steam valve, the ejected steam valve, the mixing steam valve and the condensate valve, combined with the speed regulation of the feedwater pump, to maintain stable feedwater flow and control the boiler water level fluctuation range within ±50mm. It should be noted that during condensate recovery, the temperature difference between the condensate entering the high-pressure heater and the steam temperature inside the high-pressure heater should be controlled to be ≤30℃ to reduce thermal shock and protect the high-pressure heater equipment.

[0030] The speed regulation of the water supply pump adopts PID closed-loop control, with a speed regulation response time of ≤2s, ensuring that the fluctuation of water supply flow is ≤±0.3t / h.

[0031] The steam trap is an adjustable steam trap with an opening range of 0-100%, which can be adjusted in real time according to the drainage flow to avoid drainage leakage or stagnation.

[0032] S5 monitors unit load changes in real time. When the actual unit load rises to more than 40% of the rated load, it shuts down the low-load water supply control mode and switches to the normal water supply mode.

[0033] According to an embodiment of the present invention, the operating status information includes the rated load of the coal-fired power generation unit, the current actual load, the main steam pressure and flow rate, the turbine regenerative extraction steam pressure and flow rate, the feedwater temperature and flow rate, the boiler water level, and the economizer outlet flue gas temperature parameters.

[0034] The monitoring threshold for the economizer outlet flue gas temperature is ≥120℃. When the economizer outlet flue gas temperature is detected to be lower than this threshold, the controller will simultaneously accelerate the low-load feedwater heating regulation rhythm and prioritize increasing the feedwater temperature.

[0035] According to an embodiment of the present invention, in step S1, the frequency of parameter acquisition is 1-5Hz, and the response time of operating condition identification is ≤10s; the low load operating condition also includes scenarios where the unit load fluctuates frequently and the fluctuation amplitude is ≥5% of the rated load / minute.

[0036] According to an embodiment of the present invention, in step S3, the low-load feedwater heater adopts a shell-and-tube structure, with feedwater flowing in the tube side and mixed steam flowing in the shell side, and the heat exchange temperature difference is controlled at 15-25℃; when the feedwater temperature at the outlet of the low-load feedwater heater is lower than the set value, the mixed steam flow rate is increased, the ejector ratio of the jet heat pump is adjusted, and the mixed steam pressure and temperature are adjusted accordingly.

[0037] According to an embodiment of the present invention, in step S4, the adjustment of the feedwater flow rate adopts a three-impulse control and variable parameter adjustment mode, with the boiler water level as the main control signal, the steam flow rate as the feedforward signal, and the feedwater flow rate as the feedback signal. The PID parameters are dynamically adjusted according to the load changes, and the feedwater pump adopts variable frequency speed control with a speed range of 30%-100% of the rated speed.

[0038] According to an embodiment of the present invention, in step S5, the operating condition switching process adopts a gradual control method, with the mixed steam flow rate and feedwater pump speed gradually adjusted, and the switching time controlled within 30-60 seconds to avoid system fluctuations caused by sudden load changes.

[0039] According to an embodiment of the present invention, in step S3, the outlet water temperature of the low-load water heater is monitored redundantly by setting two independent temperature sensors. When the difference between the measurements of the two sensors is ≥5℃, an abnormal temperature alarm is issued.

[0040] According to an embodiment of the present invention, in step S4, the control standards for water quality are: water hardness ≤2μmol / L, dissolved oxygen ≤15μg / L, iron content ≤20μg / L, and copper content ≤5μg / L. The water quality is monitored in real time by an online water quality monitoring module. When the water quality exceeds the standards, the controller automatically starts the water purification device for treatment.

[0041] It should be noted that the online water quality monitoring module monitors at a frequency of 2-5Hz. When the water quality exceeds the control standard for 30 consecutive seconds, the controller will issue a water quality alarm signal and activate the enhanced treatment mode of the water purification device.

[0042] To achieve the above-mentioned objectives, the second technical solution adopted by the present invention is: a water supply system for a coal-fired power generation unit under low-load conditions, comprising a processor, a memory, and at least one program, wherein the program is stored in the memory and configured to be executed by the processor, and the program includes instructions for executing a water supply method for a coal-fired power generation unit under low-load conditions.

[0043] In summary, the present invention has the following advantages compared with the prior art: 1. Effectively solves the core pain point of low-load feedwater and ensures safe and stable operation of the unit: Through optimized matching of steam source and graded heating regulation, the feedwater temperature at the outlet of the low-load feedwater heater is controlled above 150℃, avoiding corrosion and ash accumulation caused by excessively low flue gas temperature at the economizer outlet, while ensuring stable and efficient operation of the denitrification system to meet environmental emission requirements; combined with dynamic flow control and variable frequency speed regulation of feedwater pump, the boiler water level fluctuation is controlled within ±50mm, avoiding feedwater pump cavitation, solving the problem of unstable feedwater flow, and adapting to low-load and frequent load fluctuation conditions.

[0044] 2. Improve energy efficiency and reduce operating costs: By mixing and pressurizing the main steam and regenerated extraction steam through a jet heat pump, the waste heat of the regenerated extraction steam is fully recovered and utilized, reducing the consumption of main steam; at the same time, the condensate generated by the low-load feedwater heater is recovered and introduced into the high-pressure heater for recycling, minimizing heat loss and reducing unit energy consumption; the feedwater pump adopts variable frequency speed control to adapt to low-load flow demand, avoid ineffective energy consumption, and further improve the system economy.

[0045] 3. Precise control, strong adaptability, and convenient operation: The control system collects multi-dimensional operating parameters in real time, with a working condition identification response time of ≤10s. It can quickly switch between low-load control mode and normal mode, adapting to scenarios with frequent fluctuations in unit load. Each steam valve and condensate valve adopts stepless adjustment, combined with feedforward + feedback composite control logic, resulting in high control accuracy. It can dynamically optimize control parameters according to changes in unit load, without requiring a lot of manual intervention, thus reducing operation and maintenance costs.

[0046] 4. Simple structure, low modification difficulty, and strong practicality: This system is based on the optimization and modification of the existing water supply system of coal-fired power generating units. It does not require the addition of complex auxiliary equipment, has strong compatibility, short modification cycle, and low cost. The method and steps are clear and the connection with the existing unit operation process is smooth. It can be directly applied to the low-load water supply control of various coal-fired power generating units and has broad prospects for promotion and application.

[0047] 5. High system reliability and convenient operation and maintenance: By setting auxiliary components such as exhaust valves, pressure gauges, and thermometers, the system can monitor the operating status in real time, promptly discharge non-condensable gases, and provide early warning of abnormal parameters; the alarm module can issue audible and visual alarms and initiate emergency control when parameters exceed limits, reducing the risk of unit operation; each piece of equipment has a mature structure and low operation and maintenance difficulty, which can effectively reduce the workload of operation and maintenance personnel.

[0048] Those skilled in the art will understand that, for ease of explanation, the example is provided with one memory and one processor. In actual terminals or servers, multiple processors and memories may exist. Memory can also be referred to as storage medium or storage device, etc., and the embodiments of this application do not limit this.

[0049] It should be understood that in the embodiments of this application, the processor may be a Central Processing Unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The processor may also be a general-purpose microprocessor, graphics processing unit (GPU), or one or more integrated circuits to execute relevant programs to achieve the functions required by the embodiments of this application.

[0050] The processor can also be an integrated circuit chip with signal processing capabilities. In implementation, each step of this application can be completed through integrated logic circuits in the processor hardware or instructions in software form. The aforementioned processor can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The steps of the methods disclosed in the embodiments of this application can be directly manifested as execution by a hardware decoding processor, or execution by a combination of hardware and software modules in the decoding processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory; the processor reads information from the memory and, in conjunction with its hardware, completes the functions required by the units included in the methods, systems, and storage media of the embodiments of this application.

[0051] It should also be understood that the memory mentioned in the embodiments of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. Non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory can be random access memory (RAM), which is used as an external cache.

[0052] By way of example, but not limitation, many forms of RAM are available, such as Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDR SDRAM), Enhanced Synchronous DRAM (ESDRAM), Synchlink DRAM (SLDRAM), and Direct Rambus RAM (DR RAM).

[0053] The memory can also be a Compact Disc Read-Only Memory (CD-ROM) or other optical disc storage, optical disk storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media, or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures that can be accessed by a computer, but is not limited thereto. The memory can exist independently and be connected to the processor via a bus. The memory can also be integrated with the processor. The memory can store programs, and when the program stored in the memory is executed by the processor, the processor performs the various steps of the method determined in the above embodiments of this application.

[0054] It should be noted that when the processor is a general-purpose processor, DSP, ASIC, FPGA, or other programmable logic device, discrete gate or transistor logic device, or discrete hardware component, the memory (storage module) is integrated into the processor. It should be noted that the memory described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0055] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0056] In implementation, each step of the above method can be completed by integrated logic circuits in the processor's hardware or by instructions in software. The steps of the method disclosed in the embodiments of this application can be directly implemented by a hardware processor, or by a combination of hardware and software modules within the processor. The software modules can reside in mature storage media in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, or registers. Since this storage medium is located in memory, the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method; to avoid repetition, these will not be described in detail here.

[0057] Those skilled in the art will recognize that the various illustrative logical blocks (ILBs) and steps described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this application.

[0058] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer-programmed program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a processor, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a computer network, or other programmable device.

[0059] This embodiment also provides a computer-readable storage medium storing a computer program that causes a computer to execute in order to implement the above-described method based on multi-stage vortex and intelligent feedforward.

[0060] It should be noted that computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic) or wireless (e.g., infrared, wireless, microwave, etc.) means, or from one website, computer, server, or data center to a mobile phone processor via a wired means. A computer-readable storage medium can be any usable medium that a computer can access, or a data storage system such as a server or data center that integrates one or more usable media. Usable media can be magnetic media (e.g., floppy disks, hard disks), optical media (e.g., DVDs), or semiconductor media (e.g., solid-state drives), etc.

[0061] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A water supply method for a coal-fired power generation unit under low-load conditions, characterized in that, include: S1: Real-time collection of operating status information of coal-fired power generation units to determine whether the unit is under low load conditions. If the current actual load is ≤40% of the rated load, the low load water supply control mode is activated. S2, extract the main steam in the main steam pipeline as the ejector steam, extract the regenerated steam with the highest pressure in the turbine section as the ejected steam, mix the ejector steam and the ejected steam and pressurize them to obtain mixed steam; S3, after the mixed steam is regulated by the mixed steam valve, it is sent to the steam side of the low-load feedwater heater. At the same time, the feedwater that has been preheated by the high-pressure heater is sent to the water side of the low-load feedwater heater. The mixed steam is used to reheat the feedwater, and the feedwater outlet temperature of the low-load feedwater heater is controlled to be no less than 150℃. S4, after the condensate generated by the low-load feedwater heater is regulated by the condensate valve, is introduced into the steam side of the high-pressure heater for recycling; real-time monitoring of feedwater temperature, flow rate and boiler water level parameters, by adjusting the opening of the steam valve, the ejected steam valve, the mixing steam valve and the condensate valve, combined with the speed regulation of the feedwater pump, to maintain stable feedwater flow and control the boiler water level fluctuation range within ±50mm. S5 monitors unit load changes in real time. When the actual unit load rises to more than 40% of the rated load, it shuts down the low-load water supply control mode and switches to the normal water supply mode.

2. The water supply method for a coal-fired power generating unit under low-load conditions as described in claim 1, characterized in that, The operating status information includes the rated load, current actual load, main steam pressure and flow rate, turbine regenerative extraction steam pressure and flow rate, feedwater temperature and flow rate, boiler water level, and economizer outlet flue gas temperature parameters of the coal-fired power generation unit.

3. The water supply method for a coal-fired power generating unit under low-load conditions as described in claim 2, characterized in that, In step S1, the parameter acquisition frequency is 1-5Hz, and the response time for operating condition identification is ≤10s; low-load operating conditions also include scenarios where the unit load fluctuates frequently and the fluctuation amplitude is ≥5% of the rated load / minute.

4. The water supply method for a coal-fired power generating unit under low-load conditions as described in claim 3, characterized in that, In step S3, the low-load feedwater heater adopts a shell-and-tube structure, with feedwater flowing in the tube side and mixed steam flowing in the shell side, and the heat exchange temperature difference is controlled at 15-25℃. When the feedwater temperature at the outlet of the low-load feedwater heater is lower than the set value, the mixed steam flow rate is increased, the ejector ratio of the jet heat pump is adjusted, and the mixed steam pressure and temperature are adjusted accordingly.

5. The water supply method for a coal-fired power generating unit under low-load conditions as described in claim 4, characterized in that, In step S4, the feedwater flow rate is adjusted using a three-impulse control and variable parameter adjustment mode. The boiler water level is the main control signal, the steam flow rate is the feedforward signal, and the feedwater flow rate is the feedback signal. The PID parameters are dynamically adjusted according to the load changes. The feedwater pump adopts variable frequency speed control with a speed range of 30%-100% of the rated speed.

6. The water supply method for a coal-fired power generating unit under low-load conditions as described in claim 4, characterized in that, In step S5, the operating condition switching process adopts gradual control, with the mixed steam flow rate and feedwater pump speed gradually adjusted, and the switching time controlled within 30-60 seconds to avoid system fluctuations caused by sudden load changes.

7. The water supply method for a coal-fired power generating unit under low-load conditions as described in claim 1, characterized in that, In step S3, redundant monitoring is used for the outlet water temperature of the low-load water heater. Two independent temperature sensors are set up. When the difference between the measurements of the two sensors is ≥5℃, an abnormal temperature alarm is issued.

8. The water supply method for a coal-fired power generating unit under low-load conditions as described in claim 1, characterized in that, In step S4, the water quality control standards are: water hardness ≤2μmol / L, dissolved oxygen ≤15μg / L, iron content ≤20μg / L, and copper content ≤5μg / L. The water quality is monitored in real time by the online water quality monitoring module. When the water quality exceeds the standards, the controller automatically starts the water purification device for treatment.

9. A water supply system for a coal-fired power generation unit under low-load conditions, characterized in that, It includes a processor, a memory, and at least one program, the program being stored in the memory and configured to be executed by the processor, the program including instructions for executing a water supply method for a coal-fired power generation unit under low-load conditions as claimed in any one of claims 1-8.

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