An air preheater system and its control method

Abstract

This application provides an air preheater system and control method, including an inlet flue, a heat exchange flue, an outlet flue, and air pipelines. The heat exchange flue is located between the inlet and outlet flues and includes a first flue and a second flue connected in parallel. A first primary air preheater is installed in the first flue, and a second primary air preheater is installed in the second flue. The air pipelines include a first primary air pipeline and a second primary air pipeline. The first primary air pipeline is connected to the primary air inlet of the first primary air preheater, and the second primary air pipeline is connected to the primary air inlet of the second primary air preheater. The second primary air pipeline is connected in parallel to the first primary air pipeline. This application enables precise control of the primary air temperature within a suitable range under full-load conditions of a coal-fired unit, ensuring efficient and stable combustion of pulverized coal and preventing ammonium bisulfate deposition at the end of the air preheater.

Description

Technical Field

[0001] This application relates to the field of coal-fired power generation technology, and more specifically, to an air preheater system and control method. Background Technology

[0002] Currently, to adapt to the rapid development of new energy sources, coal-fired power generating units often need to operate flexibly, promoting the grid's priority consumption of new energy power through deep peak shaving. However, under deep peak shaving conditions, the amount of fuel entering the coal-fired boiler is far lower than the design value, and the flue gas temperature is also far lower than the design value. To ensure the transportation of pulverized coal and the fullness of combustion within the furnace, the deviations of the primary and secondary air volumes from the design values ​​are relatively small. This results in the boiler's hot flue gas failing to heat the primary and secondary air to the target temperature in the coal-fired boiler's air preheater. On the one hand, because the primary air temperature does not reach the target value, its drying and heating capacity for the subsequently carried pulverized coal is insufficient, which is detrimental to the stable combustion of pulverized coal in the boiler. On the other hand, because the boiler flue gas temperature before entering the air preheater is too low, its temperature will further decrease after heat exchange with the primary and secondary air, leading to the formation of ammonium bisulfate deposits and blockages after the air preheater. Furthermore, when the unit load is too high, the boiler flue gas temperature is also high, and correspondingly, the primary air temperature after being heated by the air preheater is also higher. However, excessively high primary air temperatures can lead to premature combustion of pulverized coal, posing an explosion risk. In summary, for coal-fired boilers operating at full load, maintaining the primary air temperature within a suitable range is crucial for the safe, economical, and stable operation of coal-fired units. Summary of the Invention

[0003] In view of this, the purpose of this application is to provide an air preheater system and control method, which aims to accurately control the primary air temperature within a suitable range, thereby ensuring that the coal-fired boiler can operate efficiently and stably under full load conditions.

[0004] In a first aspect, this application provides a control method for an air preheater system. The air preheater system includes an inlet flue, a heat exchange flue, an outlet flue, and an air duct. The heat exchange flue is disposed between the inlet flue and the outlet flue. The heat exchange flue includes a first flue and a second flue arranged in parallel. A first primary air preheater is disposed in the first flue, and a second primary air preheater is disposed in the second flue. The air duct includes a first primary air duct and a second primary air duct. The first primary air duct is connected to the primary air inlet of the first primary air preheater, and the second primary air duct is connected to the primary air inlet of the second primary air preheater. The method includes: controlling a primary air fan to draw primary air into the first primary air duct, exchanging heat with the hot flue gas flowing through the first flue through the first primary air preheater, so that the primary air absorbs the heat of the hot flue gas and increases in temperature; detecting the primary air temperature in the primary air box; if the primary air temperature value does not reach the target limit range, opening the regulating valve on the second primary air duct, so that the primary air flows through the first primary air duct and the second primary air duct, so as to heat the temperature of the primary air to the target limit range through the first primary air preheater and the second primary air preheater.

[0005] In one possible implementation, a secondary air preheater is also provided in the second flue. The secondary air preheater is located below the second primary air preheater and is connected in series with the second primary air preheater. The air pipeline also includes a secondary air pipeline that passes through the shell side of the secondary air preheater.

[0006] In one possible implementation, a flue gas baffle is provided at the outlet of the first flue to control the flow rate of hot flue gas flowing through the first flue.

[0007] In one possible implementation, the flue gas damper is controlled by increasing the opening of the flue gas damper when the temperature of the primary air is detected to be lower than the lower limit of the target limit range, thereby increasing the flow rate of hot flue gas in the first flue and raising the temperature of the primary air to within the target limit range.

[0008] In one possible implementation, the opening of the flue gas damper on the outlet flue is controlled by reducing the opening of the flue gas damper when the temperature of the primary air is detected to be higher than the upper limit of the target limit range. This reduces the flow rate of hot flue gas in the first flue, thereby lowering the temperature of the primary air to within the target limit range.

[0009] In one possible implementation, the first primary air preheater includes at least two, all of which are arranged in series along the direction of hot flue gas flow in the first flue. The secondary air preheater includes at least one, all of which are arranged in series along the direction of hot flue gas flow in the second flue.

[0010] In one possible implementation, the primary airflow passes through the tube side of the first primary air preheater and the tube side of the second primary air preheater, and the hot flue gas flows through the shell side of the first primary air preheater and the shell side of the second primary air preheater; or, the primary airflow passes through the shell side of the first primary air preheater and the shell side of the second primary air preheater, and the hot flue gas flows through the tube side of the first primary air preheater and the tube side of the second primary air preheater.

[0011] Secondly, this application provides an air preheater system, which includes an inlet flue, a heat exchange flue, an outlet flue, an air duct, and a controller. The heat exchange flue is disposed between the inlet flue and the outlet flue, and includes a first flue and a second flue arranged in parallel. A first primary air preheater is disposed in the first flue, and a second primary air preheater is disposed in the second flue. The air duct includes a first primary air duct and a second primary air duct. The first primary air duct passes through the shell side of the first primary air preheater, and the second primary air duct passes through the shell side of the second primary air preheater. The controller is configured to: control the primary air fan to draw primary air into the first primary air duct, where it exchanges heat with the hot flue gas flowing through the first flue through the first primary air preheater, causing the primary air to absorb heat from the hot flue gas and increase its temperature; detect the temperature value of the primary air; if the temperature value of the primary air does not reach the target limit range, open the regulating valve on the second primary air duct, allowing primary air to flow through the first and second primary air ducts, so as to heat the temperature of the primary air to the target limit range through the first and second primary air preheaters.

[0012] Thirdly, this application also provides an electronic device, including: a processor, a memory, and a bus, wherein the memory stores machine-readable instructions executable by the processor, and when the electronic device is running, the processor communicates with the memory via the bus, and when the machine-readable instructions are executed by the processor, the steps of the method described above are performed.

[0013] Fourthly, this application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, performs the steps of the method described above.

[0014] This application provides an air preheater system and control method. The air preheater system includes an inlet flue, a heat exchange flue, an outlet flue, and air ducts. The heat exchange flue is located between the inlet and outlet flues. The heat exchange flue includes a first flue and a second flue connected in parallel. A first primary air preheater is installed in the first flue, and a second primary air preheater is installed in the second flue. The air ducts include a first primary air duct and a second primary air duct. The first primary air duct passes through the shell side of the first primary air preheater, and the second air duct passes through the shell side of the second primary air preheater. This application enables precise control of the primary air temperature within a suitable range under full-load conditions of a coal-fired unit, ensuring efficient and stable combustion of pulverized coal and preventing ammonium bisulfate deposition at the end of the air preheater.

[0015] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of an air preheater system provided in an embodiment of this application;

[0018] Figure 2 A flowchart of a control method for an air preheater system provided in an embodiment of this application;

[0019] Figure 3 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. Based on the embodiments of this application, every other embodiment obtained by those skilled in the art without inventive effort falls within the scope of protection of this application.

[0021] First, the applicable scenarios for this application will be introduced. This application can be applied to coal-fired power generation technology.

[0022] Research has found that to achieve carbon neutrality and green sustainable development goals, my country's energy structure is transitioning towards low-carbon, clean wind and solar energy. However, given the volatility, intermittency, and randomness of wind and solar energy, coal-fired power generation will remain a regulatory and supporting power source for a long time to come. Flexible operation will promote grid connection of new energy sources and ensure energy supply when new energy sources are insufficient. The original design of coal-fired power generating units was primarily based on full-load, stable, and continuous operation. Under flexible operation, the unit's operating conditions deviate from the design, making related equipment prone to failure. Among these, the air preheater, as a key piece of equipment in coal-fired power plants, faces severe safety challenges under flexible operation. Especially when operating at low loads (often below 30% of the design load), the temperature of the hot flue gas used to heat the primary and secondary air is far below the design value. This not only weakens the heating capacity of the air preheater and affects the combustion efficiency of pulverized coal, but may also lead to the deposition of ammonium bisulfate, which corrodes the heat exchange surface of the air preheater. In addition, with the adjustment of the energy structure, the fuels used by in-service coal-fired units have also changed. For example, the use of high-moisture coal such as high-alkali coal from Zhundong, Xinjiang, places higher demands on the primary air temperature, further exacerbating the operating pressure on the air preheater.

[0023] Currently, the design and selection of air preheaters are based on the unit's design operating conditions, which limits their ability to regulate the primary and secondary air temperatures as well as the exhaust gas temperature at the tail end of the air preheater. Under flexible operation and high-moisture coal combustion conditions, the primary air volume needs to be increased to ensure pulverized coal drying output. This further reduces the exhaust gas temperature at the tail end of the air preheater, exacerbating ammonium bisulfate deposition and corrosion and blockage of the heating surfaces. Conversely, if the design is based on low load or high-moisture coal, the exhaust gas temperature at the tail end of the air preheater will increase under high load and low-moisture coal operating conditions, reducing boiler efficiency and affecting the unit's economic performance.

[0024] Based on this, the embodiments of this application provide an air preheater system and control method, which not only ensures that the primary and secondary air temperatures meet the flexible operation requirements of the coal-fired unit, but also avoids the deposition and corrosion of ammonium bisulfate due to excessively low exhaust gas temperature at the tail end of the air preheater, and prevents excessively high exhaust gas temperature from reducing boiler efficiency.

[0025] Please see Figure 1 , Figure 1 This is a schematic diagram of an air preheater system provided as an embodiment of this application. Figure 1 As shown, the boiler includes: an inlet flue 110, a heat exchange flue 120, an outlet flue 130, an air pipeline, a first primary air preheater 151, a second primary air preheater 153, a secondary air preheater 152, a regulating valve 170, and a flue gas damper 180. The heat exchange flue includes the first flue 121 and the second flue 122, and the air pipeline includes the first primary air pipeline 141, the second primary air pipeline 143, and the secondary air pipeline 142.

[0026] Specifically, the first primary air duct 141 is connected to the primary air inlet of the first primary air preheater 151, where the primary air exchanges heat with the hot flue gas discharged from the boiler, thereby being heated. The first flue 121 specifically refers to the flue connected to the first primary air preheater 151, used to transport the primary air. The second primary air duct 143 is connected to the primary air inlet of the second primary air preheater 153. When the primary air needs additional heating, it flows into the second primary air preheater 153 through this duct. The second primary air preheater 153 is used to further heat the primary air when needed to ensure that it reaches the target limit range. The second primary air duct 143 is connected in parallel to the first primary air duct 141. A regulating valve 170 is provided on the second primary air duct 143. The regulating valve 170 is used to control the primary air to flow into both the first and second primary air preheaters 151 and 153 simultaneously when needed. A secondary air preheater 152 is also installed in the second flue 122. The secondary air preheater 152 is located below the second primary air preheater 153. The air preheater system also includes a secondary air duct 142, which passes through the shell side of the secondary air preheater 152.

[0027] In this embodiment, primary air flows through the tube side of the first primary air preheater 151 and the tube side of the second primary air preheater 153, while hot flue gas flows through the shell side of the first primary air preheater 151 and the shell side of the second primary air preheater 153. Alternatively, primary air flows through the shell side of the first primary air preheater 151 and the shell side of the second primary air preheater 153, while hot flue gas flows through the tube side of the first primary air preheater 151 and the tube side of the second primary air preheater 153.

[0028] As an example, if primary air flows through the shell side of the first primary air preheater 151 via the first primary air duct 141, allowing air to flow on the shell side and exchange heat with the hot flue gas flowing on the tube side; and the second primary air duct 143 flows through the shell side of the second primary air preheater 153, similarly allowing air to flow on the shell side and exchange heat with the hot flue gas flowing on the tube side. The first primary air duct 141 and the second primary air duct 143 are connected in parallel to adjust the airflow path when needed. Since the air preheater used is a shell-and-tube type, according to the design, the hot flue gas can be selected to flow from the tube side or the shell side, and the air will correspondingly flow from the shell side or the tube side (opposite to the flow direction of the hot flue gas) to achieve effective heat transfer.

[0029] As an example, the first primary air preheater 151 includes at least two, which are arranged in series along the direction of hot flue gas flow in the first flue 121. The first primary air preheater 151 can be arranged in 2 to 4 stages.

[0030] The secondary air preheater 152 includes at least one, and all secondary air preheaters 152 are arranged in series along the direction of hot flue gas flow in the second flue 122. The secondary air preheaters 152 can be arranged in 1 to 3 stages.

[0031] Please see Figure 2 , Figure 2 A flowchart illustrating a control method for an air preheater system for a boiler, provided as an embodiment of this application. Figure 2 As shown, it includes:

[0032] S101. Control the primary air fan to draw primary air into the first primary air duct 141, and exchange heat with the hot flue gas flowing through the first flue 121 through the first primary air preheater 151, so that the primary air absorbs the heat of the hot flue gas and increases its temperature.

[0033] Here, primary air is the main airflow used to carry pulverized coal into the boiler for combustion. The primary air is heated by the first primary air preheater 151 to improve the combustion efficiency and stability of the pulverized coal.

[0034] S102. Detect the temperature value of the primary air.

[0035] Here, the temperature of the primary air can be measured by detecting the temperature inside the primary air box.

[0036] In a preferred embodiment of this application, if the temperature at the outlet of the first primary air preheater 151 is low, the opening of the flue gas baffle 180 on the first flue 121 can be adjusted to regulate the flue gas flow rate in the first flue 121.

[0037] Here, a flue gas damper 180 is installed at the hot flue gas outlet of the first flue 121. The flow rate of hot flue gas in the first flue 121 and the second flue 122 is adjusted by the opening of the flue gas damper 180, which in turn can also adjust the heat exchange between the primary air, the secondary air and the hot flue gas, so as to achieve a wide range of adjustment of the primary air temperature and the exhaust gas temperature.

[0038] In a preferred embodiment of this application, the opening of the flue gas damper 180 on the first flue 121 can be controlled in the following way: when the temperature value of the primary air is detected to be lower than the lower limit of the target limit range, the opening of the flue gas damper 180 is increased, thereby increasing the flow rate of hot flue gas in the first flue 121 so that the first primary air preheater 151 heats the primary air, thereby raising the temperature value of the primary air to within the target limit range.

[0039] In a preferred embodiment of this application, when the temperature of the outlet flue 130 is detected to be too high, the opening of the flue gas damper 180 on the first flue 121 can be controlled in the following way: when the temperature value of the primary air is detected to be higher than the upper limit of the target limit range, the opening of the flue gas damper 180 is controlled to decrease, thereby reducing the flow rate of hot flue gas in the first flue 121, so that the temperature value of the primary air is reduced to within the target limit range, thereby improving the utilization rate of hot flue gas in the first flue 121.

[0040] return Figure 1 S103. If the temperature of the primary air does not reach the target limit range, the regulating valve 170 on the second primary air pipeline 143 is opened, so that the primary air flows through the first primary air pipeline 141 and the second primary air pipeline 143 respectively, so as to heat the temperature of the primary air to the target limit range through the first primary air preheater 151 and the second primary air preheater 153.

[0041] Specifically, the target limit range refers to the ideal temperature range that the primary air needs to reach to ensure that the pulverized coal can burn stably and efficiently in the boiler. The regulating valve 170 is a device used to control the flow rate, pressure or temperature of fluids. It is used to control the amount of primary air flowing into the secondary primary air pipeline 143, thereby regulating the heat exchange between the primary air, secondary air and hot flue gas, and realizing a wide range of adjustment of the primary air temperature and flue gas temperature. Not reaching the target limit range means that the boiler's flexible operating load is low.

[0042] Compared to other technologies, this application employs a separate, staged arrangement of primary and secondary air preheaters within the flue gas duct. Furthermore, a portion of the primary air preheaters are positioned upstream of the secondary air preheaters and connected in parallel with the primary air preheaters within the primary air heating flue. By adjusting the amount of primary air entering the primary air preheaters within the primary air heating flue and the amount entering the primary air preheaters within the secondary air heating flue, the heat absorption of the primary air from the flue gas in both the primary and secondary air heating flues is regulated, achieving a wide range of adjustment for the primary air temperature and the exhaust temperature downstream of the primary air heating flue. Simultaneously, by combining the adjustment of the secondary air volume and target secondary air temperature, the total heat released by the flue gas in the secondary air heating flue to the primary and secondary air is controlled, achieving a wide range of adjustment for the exhaust temperature downstream of the secondary air heating flue. In addition, by adjusting the opening of the flue gas damper at the outlet of the primary air heating flue, the amount of flue gas flowing through the primary air heating flue and the secondary air heating flue is controlled. At the same time, the amount of primary air and secondary air flowing through the air preheater in the primary air heating flue and the secondary air heating flue are matched, and the heat exchange between the flue gas and the air in each flue is adjusted from the flue gas side, thereby improving the adjustment range of the exhaust gas temperature and the primary air and secondary air temperatures.

[0043] This application embodiment also provides a pulverized coal combustion system for a boiler, corresponding to the control method for an air preheater system for a boiler. The air preheater system includes an inlet flue, a heat exchange flue, an outlet flue, air pipes, and a controller. The heat exchange flue is located between the inlet flue and the outlet flue, and includes a first flue and a second flue connected in parallel. A first primary air preheater is installed in the first flue, and a second primary air preheater is installed in the second flue. The air pipes include a first primary air pipe and a second primary air pipe. The first primary air pipe passes through the shell side of the first primary air preheater, and the second primary air pipe passes through the second primary air preheater. On the shell side of the air preheater, the controller is configured to: control the primary air fan to draw primary air into the first primary air duct, where it exchanges heat with the hot flue gas flowing through the first flue through the first primary air preheater, causing the primary air to absorb heat from the hot flue gas and increase its temperature; detect the primary air temperature in the primary air box; if the primary air temperature value does not reach the target limit range, open the regulating valve on the second primary air duct, allowing the primary air to flow through the first and second primary air ducts, so as to heat the primary air temperature to the target limit range through the first and second primary air preheaters.

[0044] Please see Figure 3 , Figure 3 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Figure 3 As shown, the electronic device 400 includes a processor 410, a memory 420, and a bus 430.

[0045] The memory 420 stores machine-readable instructions executable by the processor 410. When the electronic device 400 is running, the processor 410 communicates with the memory 420 via the bus 430. When the machine-readable instructions are executed by the processor 410, they can perform the operations described above. Figure 2 The steps of the method in the illustrated embodiment can be found in the method embodiment for specific implementation methods, which will not be repeated here.

[0046] This application also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, can perform the above-described actions. Figure 2 The steps of the method in the illustrated method embodiment can be found in the method embodiment for specific implementation methods, which will not be repeated here.

[0047] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0048] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the shown or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0049] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0050] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0051] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0052] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The scope of protection of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A control method of an air preheater system, characterized by, The air preheater system comprises an inlet flue, a heat exchange flue, an outlet flue, and an air pipeline, the heat exchange flue is arranged between the inlet flue and the outlet flue, the heat exchange flue comprises a first flue and a second flue arranged in parallel, the first flue is provided with a first primary air air preheater, the second flue is provided with a second primary air air preheater, the air pipeline comprises a first primary air air pipeline and a second primary air air pipeline, the first primary air air pipeline is connected with a primary air air inlet of the first primary air air preheater, the second primary air air pipeline is connected with a primary air air inlet of the second primary air air preheater, the second primary air air pipeline is connected in parallel to the first primary air air pipeline, wherein the second primary air air pipeline is connected in parallel to the first primary air air pipeline after the first primary air air preheater, the first primary air air preheater comprises a front-stage first primary air air preheater and a rear-stage first primary air air preheater, the front-stage first primary air air preheater and the rear-stage first primary air air preheater are arranged in series along the flow direction of hot flue gas in the first flue, and the rear-stage first primary air air preheater is arranged in parallel with the second primary air air preheater. The method comprises: controlling a primary air fan to draw primary air into the first primary air air pipeline, and performing heat exchange between the primary air and hot flue gas flowing through the first flue through the front-stage first primary air air preheater and the rear-stage first primary air air preheater, so that the primary air absorbs heat from the hot flue gas and increases in temperature; detecting a temperature value of the primary air; if the temperature value of the primary air does not reach a target limit value range, opening a regulating valve on the second primary air air pipeline, so that the primary air flowing through the front-stage first primary air air preheater is divided into two paths, and the two paths of the primary air flow through the rear-stage first primary air air preheater and the second primary air air preheater respectively, and then mix, and the hot flue gas flowing through the first flue and the second flue respectively heats the primary air in the rear-stage first primary air air preheater and the second primary air air preheater, so as to heat the temperature of the primary air to the target limit value range.

2. The method of claim 1, wherein, The second flue is further provided with a secondary air air preheater, the secondary air air preheater is arranged below the second primary air air preheater and in series with the second primary air air preheater, and the air pipeline further comprises a secondary air air pipeline, the secondary air air pipeline passes through a shell side of the secondary air air preheater.

3. The method of claim 1, wherein, A flue gas baffle is arranged at the outlet of the first flue, for controlling the flow of hot flue gas flowing through the first flue.

4. The method of claim 3, wherein, The flue gas baffle is controlled in the following manner: when it is detected that the temperature value of the primary air is lower than the lower limit of the target limit value range, the opening degree of the flue gas baffle is increased, so as to increase the flow of hot flue gas in the first flue, and the temperature value of the primary air is increased to the target limit value range.

5. The method of claim 4, wherein, The opening degree of the flue gas damper on the outlet flue is controlled in the following manner: When it is detected that the temperature value of the primary air is higher than the upper limit of the target limit interval, the opening degree of the flue gas damper is controlled to decrease, so that the temperature value of the primary air is reduced to the target limit interval by reducing the hot flue gas flow in the first flue.

6. The method of claim 2, wherein, The secondary air preheater comprises at least one, all of the secondary air preheaters are arranged in series along the hot flue gas flow direction in the second flue.

7. The method of claim 1, wherein, The primary air flows through the tube side of the front-stage first primary air preheater, the tube side of the rear-stage first primary air preheater and the tube side of the second primary air preheater, and the hot flue gas flows through the shell side of the front-stage first primary air preheater, the shell side of the rear-stage first primary air preheater and the shell side of the second primary air preheater, Or, The primary air flows through the shell side of the front-stage first primary air preheater, the shell side of the rear-stage first primary air preheater and the shell side of the second primary air preheater, and the hot flue gas flows through the tube side of the front-stage first primary air preheater, the tube side of the rear-stage first primary air preheater and the tube side of the second primary air preheater.

8. An air preheater system characterized by, The air preheater system comprises an inlet flue, a heat exchange flue, an outlet flue, an air pipeline and a controller, the heat exchange flue is arranged between the inlet flue and the outlet flue, the heat exchange flue comprises a first flue and a second flue arranged in parallel, the first flue is provided with a first primary air preheater, the second flue is provided with a second primary air preheater, the air pipeline comprises a first primary air pipeline and a second primary air pipeline, the first primary air pipeline passes through the shell side of the first primary air preheater, the second primary air pipeline passes through the shell side of the second primary air preheater, wherein the second primary air pipeline is parallel to the first primary air pipeline after the first primary air preheater, the first primary air preheater comprises a front-stage first primary air preheater and a rear-stage first primary air preheater, the front-stage first primary air preheater and the rear-stage first primary air preheater are arranged in series along the hot flue gas flow direction in the first flue, and the rear-stage first primary air preheater is arranged in parallel with the second primary air preheater; The controller is configured to: control the primary air fan to draw primary air into the first primary air pipeline, heat exchange between the primary air and the hot flue gas flowing through the first flue through the front-stage first primary air preheater and the rear-stage first primary air preheater, so that the primary air absorbs heat from the hot flue gas and increases in temperature; detect the temperature value of the primary air; If the temperature value of the primary air does not reach the target limit interval, the regulating valve on the second primary air pipeline is opened, so that the primary air flowing through the front-stage first primary air preheater is divided into two paths, respectively flows through the rear-stage first primary air preheater and the second primary air preheater and is mixed, the hot flue gas flowing through the first flue and the second flue respectively heats the primary air in the rear-stage first primary air preheater and the second primary air preheater, so as to heat the temperature of the primary air to the target limit interval.

9. An electronic device, comprising: Comprise: A processor, a memory and a bus, the memory stores machine readable instructions executable by the processor, when the electronic device is running, the processor and the memory communicate through the bus, the processor executes the machine readable instructions to execute the steps of the method as claimed in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a computer program, when the computer program is run by the processor, the steps of the method as claimed in any one of claims 1 to 7 are executed.

Images