Plate-type air pre-heater system for relieving low-temperature blockage and corrosion of rotary air pre-heater

Abstract

The utility model discloses a plate-type air pre-heater system for relieving low-temperature blockage and corrosion of a rotary air pre-heater, relates to the field of heat energy and power engineering, and overcomes the defect that a low-temperature section of the rotary air pre-heater in the prior art is easy to corrode. According to the technical scheme, the plate type air pre-heater system for relieving low-temperature blockage and corrosion of the rotary air pre-heater comprises the rotary air pre-heater and a plate type air pre-heater assembly which are sequentially connected, and a smoke inlet of a heat exchange system is formed in a smoke inlet of the rotary air pre-heater. A smoke outlet of the heat exchange system is arranged at a smoke outlet of the plate-type air pre-heater assembly, a smoke inlet and a smoke outlet of the plate-type air pre-heater assembly are provided with pressure difference transmitters, a plurality of mutually independent air ducts are arranged in front of an air inlet of the plate-type air pre-heater assembly, switch valves are arranged at the air ducts, and the air inlets and the air outlets of the plate-type air pre-heater assembly are communicated with the air inlets of the plate-type air pre-heater assembly. The switch valves control a plurality of valve plates used for opening or closing the corresponding air ducts. The rotary air pre-heater is mainly used for solving the problem that the low-temperature section of the rotary air pre-heater is prone to corrosion.

Description

Technical Field

[0001] This application relates to the field of thermal energy and power engineering, and in particular to a plate air preheater system for mitigating low-temperature blockage and corrosion in rotary air preheaters. Background Technology

[0002] From the perspective of equipment operation, with increasingly stringent environmental standards, coal-fired boilers are generally equipped with selective catalytic reduction (SCR) denitrification systems and wet desulfurization systems. During SCR denitrification, if ammonia slip is not properly controlled (ammonia slip rate exceeds 3 ppm), the escaped ammonia will react with SO3 and water vapor in the flue gas to generate highly viscous ammonium bisulfate (NH4HSO4). Ammonium bisulfate has a melting point of 147℃ and is liquid in the low-temperature section (120-140℃) of the rotary air preheater, easily adhering to the surface of heat exchange elements, forming scale and ash deposits. This not only blocks the flue gas passages and increases system resistance but also further exacerbates low-temperature corrosion. Simultaneously, the operation of the wet desulfurization system causes the flue gas to carry a large amount of water vapor, raising the flue gas dew point temperature, increasing the risk of sulfuric acid vapor condensation, and accelerating the low-temperature corrosion process.

[0003] While existing technologies employ measures such as increasing the air preheater inlet temperature and using corrosion-resistant materials (e.g., enamel-lined pipes, ND steel) to mitigate low-temperature corrosion, limitations remain. Increasing the air temperature reduces system thermal efficiency; corrosion-resistant materials are expensive and offer limited protection under specific operating conditions, making it difficult to fundamentally solve the problem of low-temperature corrosion. Summary of the Invention

[0004] In order to overcome the shortcomings of existing rotary air preheaters in terms of easy corrosion in the low-temperature section, this application provides a plate-type air preheater system to alleviate low-temperature blockage and corrosion in rotary air preheaters, which can solve the problem of easy corrosion in the low-temperature section of rotary air preheaters.

[0005] To achieve the above objectives, this application adopts the following technical solution: a plate air preheater system for alleviating low-temperature blockage and corrosion in rotary air preheaters, comprising a rotary air preheater and a plate air preheater assembly connected in sequence. The air inlet of the heat exchange system is located at the air inlet of the plate air preheater assembly, and the air outlet is located at the air outlet of the rotary air preheater. The flue gas inlet of the heat exchange system is located at the flue gas inlet of the rotary air preheater, and the flue gas outlet of the heat exchange system is located at the flue gas outlet of the plate air preheater assembly. Differential pressure transmitters are provided at the flue gas inlet and outlet of the plate air preheater assembly. Multiple independent air ducts are provided before the air inlet of the plate air preheater assembly. Switch valves are provided at the air ducts, and the switch valves control multiple valve plates for opening or closing the corresponding air ducts.

[0006] The preferred solution in the above technical solutions is to replace a portion of the existing rotary air preheater, namely the low-temperature section, with a plate-type air preheater assembly. Since the plate-type air preheater has a more compact structure, a more regular flue gas passage, and a more uniform airflow distribution, it is less likely to have local eddies and dead zones. This can effectively prevent flue gas from stagnating in certain areas and reduce the possibility of sulfuric acid vapor condensation and corrosion caused by excessive flue gas residence time. Therefore, replacing the low-temperature section of the rotary air preheater with a plate-type air preheater assembly will increase corrosion resistance to a certain extent. The operating principle of this application is as follows: By installing differential pressure transmitters at the inlet and outlet of the plate air preheater assembly, when the pressure differential transmitter reaches a set threshold due to the accumulation of ammonium bisulfate in the flue, the corresponding air duct can be closed via a switching valve. This reduces or isolates the entry of air, thereby decreasing the heat exchange rate of the flue gas. At this time, the flue gas temperature of both the plate air preheater assembly and the rotary heat exchanger will rise, gradually increasing the vaporization degree of ammonium bisulfate in the flue gas, causing the pressure in the flue gas to drop below the threshold of the differential pressure transmitter. Subsequently, the switching valve can be reopened to restore normal airflow. This application has the following advantages: It converts the existing low-temperature section of the rotary air preheater into a plate air preheater assembly. The plate air preheater has a compact structure, regular flue gas channels, and uniform airflow distribution, making it less prone to local eddies and dead zones. It can effectively prevent flue gas from stagnating in certain areas, reducing the possibility of sulfuric acid vapor condensation and corrosion caused by excessive flue gas residence time, increasing corrosion resistance, and solving the problem of easy corrosion in the low-temperature section of the rotary air preheater. Furthermore, by installing differential pressure transmitters at the inlet and outlet of the plate air preheater assembly, when the pressure in the flue reaches a set threshold, the corresponding air duct can be closed by switching valves to reduce or isolate air entry, reduce the degree of flue gas heat exchange, and cause the flue temperature of the plate air preheater assembly to rise. This gradually increases the vaporization of ammonium bisulfate in the flue and reduces the pressure in the flue. Once the pressure drops below the threshold of the differential pressure transmitter, the switching valves can be reopened to restore normal air flow, thereby achieving automatic adjustment of the flue temperature and ensuring stable system operation.

[0007] Furthermore, the plate air preheater assembly includes a first plate air preheater and a second plate air preheater. Air flows sequentially through the air side of the second plate air preheater and the first plate air preheater, and is discharged from the air outlet of the rotary air preheater. Flue gas flows sequentially through the flue gas side of the rotary air preheater and the first plate air preheater, and is discharged from the flue gas outlet of the second plate air preheater.

[0008] By adopting the aforementioned technical solution, air and flue gas flow through different plate air preheaters in a specific order, forming a more reasonable heat exchange path. This helps to improve heat exchange efficiency, allowing air and flue gas to achieve more complete heat exchange at different stages, thereby making better use of thermal energy and improving the energy utilization efficiency of the entire system.

[0009] Furthermore, the flue gas side of the first plate-type air preheater is located below the flue gas side of the rotary air preheater, and the flue gas side of the second plate-type air preheater is located below the flue gas side of the rotary air preheater.

[0010] By adopting the aforementioned technical solution, the flue gas sides of both the first and second plate air preheaters are located below the flue gas side of the rotary air preheater. This facilitates the natural downward flow of flue gas under gravity, allowing it to flow more smoothly through the rotary, first, and second plate air preheaters sequentially, reducing flow resistance and improving system efficiency. Furthermore, flue gas dust tends to settle downwards under gravity. With the plate air preheaters located below the rotary air preheater, dust more easily settles naturally to the bottom of the plate air preheaters as it flows with the flue gas, rather than accumulating on the surfaces of heat exchange elements or within the channels. This effectively acts as a natural dust removal mechanism, reducing dust adhesion to heat exchange surfaces and mitigating the risk of decreased heat exchange efficiency and equipment blockage caused by dust accumulation.

[0011] Furthermore, the air inlet of the plate air preheater assembly includes the air inlet of the first plate air preheater and the air inlet of the second plate air preheater, and the air duct is located in front of the air inlet of the first plate air preheater, and / or the air duct is located in front of the air inlet of the second plate air preheater.

[0012] When the aforementioned technical solution is adopted, if the air duct is located only before the air inlet of the first plate air preheater, the airflow entering the first plate air preheater can be centrally controlled and adjusted. This facilitates precise operation for the specific heat exchange requirements of the plate air preheater, effectively optimizing the heat exchange process of the first plate air preheater and adapting it to different flue gas conditions and system heat exchange requirements. If the air duct is located only before the air inlet of the second plate air preheater, and if the location or operating conditions of the second plate air preheater are more susceptible to low-temperature corrosion, adjusting the amount of air entering through the air duct can effectively control the flow of air within the second plate air preheater. Temperature distribution is optimized to prevent sulfuric acid vapor condensation due to excessively low temperatures, reducing the risk of low-temperature corrosion and extending equipment lifespan. Furthermore, the airflow into the entire system can be controlled by adjusting the air intake of this duct, and the airflow into both plate heat exchangers can be controlled simultaneously to ensure the flue gas temperature is sufficient to vaporize ammonium bisulfate on the plates. When the duct is located before the air inlets of both the first and second plate air preheaters, independent adjustments can be made to meet the different heat exchange requirements of each preheater, achieving precise control over the heat exchange process of the entire plate air preheater assembly. Regardless of operating conditions or the properties of flue gas and air, the airflow in both ducts can be adjusted separately to ensure optimal heat exchange performance for each plate air preheater, significantly improving the performance and efficiency of the entire heat exchange system.

[0013] Furthermore, when the multiple valve plates controlled by the switching valve are closed, they close the corresponding air ducts one by one.

[0014] By employing the aforementioned technical solution, the closure of each air duct can be precisely controlled, enabling fine-tuning of airflow. By closing the valve plates one by one, the on / off state of each air duct can be accurately adjusted according to actual needs, thereby more precisely controlling the amount of air entering the plate air preheater to adapt to different operating conditions and heat exchange requirements. Closing the valve plates one by one avoids the airflow impact and pressure fluctuations that may occur when multiple air ducts are closed simultaneously.

[0015] Furthermore, the air side between the first plate air preheater and the second plate air preheater is connected via a C-shaped steering chamber.

[0016] Using the aforementioned technical solution, the C-shaped turning air chamber connects the air side of the first plate air preheater and the second plate air preheater, allowing air to flow smoothly and steadily between the two, reducing flow resistance and the generation of eddies, and improving the heat exchange efficiency on the air side.

[0017] Furthermore, on the air side of the C-shaped turning chamber, which is laterally away from the rotary air preheater, multiple independent air ducts are located in the C-shaped turning chamber.

[0018] By adopting the aforementioned technical solution, multiple independent air ducts are centrally arranged in the C-shaped turning air chamber, which facilitates the rational planning and layout of connecting pipes with other equipment, reduces pipe crossings and confusion, makes the pipe routing of the entire system clearer and smoother, and reduces the difficulty of pipe installation and maintenance. This layout makes the C-shaped turning air chamber and each air duct more convenient to maintain and repair.

[0019] Furthermore, the flue gas temperature at the outlet of the rotary air preheater is greater than or equal to 150°C.

[0020] Using the aforementioned technical solution, if the flue gas temperature is too low, acid dew point corrosion is likely to occur on the surfaces of equipment such as air preheaters. Maintaining the flue gas temperature at 150℃ or above ensures that the flue gas temperature is higher than the acid dew point temperature, effectively preventing acidic substances from condensing on the equipment surface, reducing the risk of corrosion, and extending the service life of the equipment. Furthermore, maintaining the flue gas temperature at 150℃ or above allows the plate heat exchanger to reduce the amount of air entering when a pressure difference occurs, ensuring that the plate temperature is the same as the flue gas temperature, both higher than the dew point temperature of ammonium bisulfate, thus aiding in the vaporization of ammonium bisulfate on the plates.

[0021] Furthermore, the switching valve includes a controller for electrical connection with the differential pressure transmitter, so that when the differential pressure transmitter reaches a set threshold, the controller receives a signal and activates the switching valve to close the corresponding air duct.

[0022] Using the aforementioned technical solution, the differential pressure transmitter can accurately monitor pressure changes within the duct in real time. When the pressure difference reaches a set threshold, it immediately sends an electrical signal to activate the switching valve, accurately closing the corresponding duct. This precise control effectively maintains pressure balance within the system, preventing problems such as unstable airflow and equipment damage caused by abnormal pressure. Attached Figure Description

[0023] The following description, in conjunction with the accompanying drawings, further illustrates this application:

[0024] Figure 1 This is a schematic diagram of a plate air preheater system for mitigating low-temperature blockage and corrosion in a rotary air preheater, as described in this application.

[0025] Figure 2 for Figure 1 A cross-sectional view along the AA direction.

[0026] Figure descriptions: 1. Rotary air preheater; 2. Plate air preheater assembly; 21. First plate air preheater; 22. Second plate air preheater; 3. Differential pressure transmitter; 4. Duct; 5. Switch valve; 6. C-type diverter chamber. Detailed Implementation

[0027] 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.

[0028] The terms "first," "second," etc. (if present) in the specification and claims of this application are used to distinguish similar objects, not to describe a specific order or sequence. Even if "second" is used before a technical feature for distinction, it does not necessarily imply the presence of "first." It should be understood that in this application, "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. It should be understood that in this application, "multiple" refers to two or more. "And / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, X and / or Y can represent: X alone, X and Y simultaneously, and Y alone. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "Containing X, Y, and Z," "Containing X, Y, and Z" means that all three X, Y, and Z are included; "Containing X, Y, or Z" means that one of X, Y, and Z is included; "Containing X, Y, and / or Z" means that any one, two, or three of X, Y, and Z are included.

[0029] The technical solutions of this application will be described in detail below with specific embodiments. The following specific embodiments can be combined or substituted with each other according to the actual situation, and the same or similar concepts or processes may not be described again in some embodiments.

[0030] like Figures 1 to 2 As shown, this application provides a plate air preheater system for mitigating low-temperature blockage and corrosion in rotary air preheaters, comprising a rotary air preheater 1 and a plate air preheater assembly 2 connected in sequence. The air inlet of the heat exchange system is located at the air inlet of the plate air preheater assembly 2, and the air outlet is located at the air outlet of the rotary air preheater 1. The flue gas inlet of the heat exchange system is located at the flue gas inlet of the rotary air preheater 1, and the flue gas outlet of the heat exchange system is located at the flue gas outlet of the plate air preheater assembly 2. Differential pressure transmitters 3 are provided at the flue gas inlet and outlet of the plate air preheater assembly 2. Multiple independent air ducts 4 are provided in front of the air inlet of the plate air preheater assembly 2. Switch valves 5 are provided at the air ducts 4, and the switch valves 5 control multiple valve plates for opening or closing the corresponding air ducts 4.

[0031] The preferred solution in the above technical solution is to convert a portion of the existing rotary air preheater 1, namely the low-temperature section, into a plate air preheater assembly 2. Since the plate air preheater has a more compact structure, a more regular flue gas passage, and a more uniform airflow distribution, it is less likely to have local eddies and dead zones. This can effectively prevent flue gas from stagnating in certain areas and reduce the possibility of sulfuric acid vapor condensation and corrosion caused by excessive flue gas residence time. Therefore, replacing the low-temperature section of the rotary air preheater 1 with the plate air preheater assembly 2 will increase corrosion resistance to a certain extent. The operating principle of this application is as follows: By installing differential pressure transmitters 3 at the inlet and outlet of the plate air preheater assembly 2, when the pressure differential transmitter 3 reaches the set threshold due to the accumulation of ammonium bisulfate in the flue, the corresponding air duct 4 can be closed by the switch valve 5, thereby reducing or isolating the air intake and reducing the heat exchange of the flue gas. At this time, the flue of the plate air preheater assembly 2 and the rotary heat exchanger is dry-burned, so that its temperature is the same as the flue gas temperature. The temperature of the liquid or solid ammonium bisulfate will also rise, gradually increasing the degree of vaporization of ammonium bisulfate in the flue, so that the pressure in the flue drops below the threshold of the differential pressure transmitter 3. Then the switch valve 5 can be reopened to restore the normal air flow. This application has the following advantages: It converts the existing rotary air preheater 1 low-temperature section into a plate-type air preheater assembly 2. The plate-type air preheater has a compact structure, regular flue gas channels, and uniform airflow distribution, making it less prone to local eddies and dead zones. This effectively prevents flue gas stagnation in certain areas, reducing the possibility of sulfuric acid vapor condensation and corrosion caused by prolonged flue gas residence time, and increasing corrosion resistance. This solves the problem of easy corrosion in the low-temperature section of the rotary air preheater 1. Furthermore, by installing differential pressure transmitters 3 at the inlet and outlet of the plate-type air preheater assembly 2, when the pressure in the flue reaches a set threshold, the corresponding air duct 4 can be closed via the switching valve 5, reducing or isolating air entry, decreasing the degree of flue gas heat exchange, and causing the flue temperature of the plate-type air preheater assembly 2 to rise. This gradually increases the vaporization of ammonium bisulfate in the flue, reducing the pressure in the flue. Once the pressure drops below the threshold of the differential pressure transmitter 3, the switching valve 5 can be reopened to restore normal airflow, achieving automatic adjustment of the flue temperature and ensuring stable system operation.

[0032] Specifically, for example, when the pressure differential transmitter 3 reaches the set threshold, the switching valve 5 is activated to close the air duct 4 for two hours, so that the flue temperature of the plate air preheater assembly 2 and the rotary heat exchanger rises to the temperature of gasifying ammonium bisulfate, reducing corrosion in the air duct 4; all plates are manufactured using laser welding and bulging molding processes.

[0033] Furthermore, the plate air preheater assembly 2 includes a first plate air preheater 21 and a second plate air preheater 22. Air flows sequentially through the air side of the second plate air preheater 22 and the first plate air preheater 21, and is discharged from the air outlet of the rotary air preheater 1. Flue gas flows sequentially through the flue gas side of the rotary air preheater 1 and the first plate air preheater 21, and is discharged from the flue gas outlet of the second plate air preheater 22.

[0034] By adopting the aforementioned technical solution, air and flue gas flow through different plate air preheaters in a specific order, forming a more reasonable heat exchange path. This helps to improve heat exchange efficiency, allowing air and flue gas to achieve more complete heat exchange at different stages, thereby making better use of thermal energy and improving the energy utilization efficiency of the entire system.

[0035] Furthermore, the flue gas side of the first plate air preheater 21 is located below the flue gas side of the rotary air preheater 1, and the flue gas side of the second plate air preheater 22 is located below the flue gas side of the rotary air preheater 1.

[0036] By adopting the aforementioned technical solution, the flue gas sides of both the first plate air preheater 21 and the second plate air preheater 22 are located below the flue gas side of the rotary air preheater 1. This facilitates the natural downward flow of flue gas under gravity, allowing it to flow more smoothly through the rotary air preheater 1, the first plate air preheater 21, and the second plate air preheater 22 sequentially. This reduces flow resistance and improves the efficiency of flue gas circulation within the system. Furthermore, the dust in the flue gas tends to settle downwards under gravity. The plate air preheaters, located below the rotary air preheater 1, make it easier for dust to naturally settle to the bottom of the plate air preheaters as it flows with the flue gas, rather than accumulating on the surface of the heat exchange elements or in the channels inside the equipment. This, to a certain extent, acts as a natural dust removal mechanism, reducing dust adhesion to the heat exchange surfaces and lowering the risk of decreased heat exchange efficiency and equipment blockage caused by dust accumulation.

[0037] Furthermore, the air side between the first plate air preheater 21 and the second plate air preheater 22 is connected by a C-shaped steering chamber 6.

[0038] Using the aforementioned technical solution, the C-shaped turning air chamber connects the air side of the first plate air preheater 21 and the second plate air preheater 22, enabling air to flow smoothly and steadily between the two, reducing flow resistance and the generation of eddies, and improving the heat exchange efficiency on the air side.

[0039] Furthermore, the air inlet of the plate air preheater assembly 2 includes the air inlet of the first plate air preheater 21 and the air inlet of the second plate air preheater 22. The air duct 4 is located in front of the air inlet of the first plate air preheater 21. A switching valve is provided at the air duct, and the switching valve controls multiple valve plates for opening or closing the corresponding air duct.

[0040] By adopting the aforementioned technical solution, when the air duct 4 is located only in front of the air inlet of the first plate air preheater 21, the air flow rate entering the first plate air preheater 21 can be centrally controlled and adjusted, which facilitates precise operation for the specific heat exchange requirements of the plate air preheater and can effectively optimize the heat exchange process of the first plate air preheater 21, making it adaptable to different flue gas conditions and system heat exchange requirements.

[0041] The preferred embodiment of this scheme is: the C-shaped turning chamber 6 is located laterally away from the air side of the rotary air preheater 1, and multiple independent air ducts 4 are arranged inside the C-shaped turning chamber 6.

[0042] By adopting the aforementioned technical solution, multiple independent air ducts 4 are centrally arranged in the C-shaped turning air chamber, which facilitates the rational planning and arrangement of connecting pipes with other equipment, reduces pipe crossings and confusion, makes the pipe routing of the entire system clearer and smoother, and reduces the difficulty of pipe installation and maintenance. This layout makes the C-shaped turning air chamber and each air duct 4 more convenient to maintain and repair.

[0043] The specific number of duct sections is determined based on the specific thermal characteristics, ensuring that the temperature of the high-temperature flue gas is maintained while the overall exhaust temperature of the main unit does not significantly affect subsequent dust removal equipment.

[0044] In another embodiment, the air duct 4 is located in front of the air inlet of the second plate air preheater 22, and a switching valve is provided at the air duct. The switching valve controls multiple valve plates for opening or closing the corresponding air duct.

[0045] The advantage of this embodiment is that when the air duct 4 is only located in front of the air inlet of the second plate air preheater 22, if the location or operating conditions of the second plate air preheater 22 are more susceptible to low-temperature corrosion, the temperature distribution inside the second plate air preheater 22 can be effectively controlled by adjusting the amount of air entering through the air duct 4. This avoids the condensation of sulfuric acid vapor due to excessively low temperatures, reduces the risk of low-temperature corrosion, and extends the service life of the equipment. Furthermore, by controlling whether air enters through the air duct 4, the air intake of the entire system can be controlled, and the air intake of the two plate heat exchangers can also be controlled simultaneously to ensure that the temperature of the flue gas is sufficient to vaporize the ammonium bisulfate on the plates.

[0046] In another embodiment, the air duct 4 is located in front of the air inlet of the first plate air preheater 21 and the second plate air preheater 22, and a switching valve is provided at the air duct. The switching valve controls multiple valve plates for opening or closing the corresponding air duct.

[0047] The advantage of this embodiment is that when the air duct 4 is simultaneously located before the air inlets of both the first plate air preheater 21 and the second plate air preheater 22, it can be independently adjusted to meet the different heat exchange requirements of the first plate air preheater 21 and the second plate air preheater 22, achieving precise control over the heat exchange process of the entire plate air preheater assembly 2. Regardless of different operating conditions or the properties of the flue gas and air, the airflow of each plate air preheater can be adjusted separately by adjusting the airflow of the two air ducts 4, ensuring optimal heat exchange performance and significantly improving the performance and efficiency of the entire heat exchange system.

[0048] Furthermore, when the multiple valve plates controlled by the switching valve 5 are closed, they close the corresponding air ducts 4 one by one.

[0049] By employing the aforementioned technical solution, the closure of each air duct 4 can be precisely controlled, enabling fine-tuning of airflow. By closing the valve plates one by one, the on / off state of each air duct 4 can be accurately adjusted according to actual needs, thereby more precisely controlling the amount of air entering the plate air preheater to adapt to different operating conditions and heat exchange requirements. Closing the valve plates one by one avoids the airflow impact and pressure fluctuations that may occur when multiple air ducts 4 are closed simultaneously.

[0050] Furthermore, the flue gas temperature at the outlet of the rotary air preheater 1 is greater than or equal to 150°C.

[0051] Using the aforementioned technical solution, if the flue gas temperature is too low, acid dew point corrosion is likely to occur on the surfaces of equipment such as air preheaters. Maintaining the flue gas temperature at 150℃ or above ensures that the flue gas temperature is higher than the acid dew point temperature, effectively preventing acidic substances from condensing on the equipment surface, reducing the risk of corrosion, and extending the service life of the equipment. Furthermore, maintaining the flue gas temperature at 150℃ or above allows the plate heat exchanger to reduce the amount of air entering when a pressure difference occurs, ensuring that the plate temperature is the same as the flue gas temperature, both higher than the dew point temperature of ammonium bisulfate, thus aiding in the vaporization of ammonium bisulfate on the plates.

[0052] Furthermore, the switching valve 5 includes a controller for electrical connection with the differential pressure transmitter 3, so that when the differential pressure transmitter 3 reaches a set threshold, the controller receives a signal and activates the switching valve 5 to close the corresponding air duct 4.

[0053] Using the aforementioned technical solution, the differential pressure transmitter 3 can accurately monitor pressure changes within the air duct 4 in real time. When the pressure difference reaches a set threshold, it immediately sends an electrical signal to activate the switching valve 5, accurately closing the corresponding air duct 4. This precise control effectively maintains pressure balance within the system, preventing problems such as unstable airflow and equipment damage caused by abnormal pressure.

[0054] The above solution can also be used in the dry-burning system of the low-temperature zone of a wide-channel corrugated plate air preheater. It can periodically soften and gasify the ammonium bisulfate that settles on the surface of the heat exchange plates, reducing its corrosion of the wall plates and reducing the resistance of flue gas. It is especially suitable for high-sulfur and high-moisture coal conditions.

[0055] In addition to the preferred embodiments described above, this application has other implementation methods. All other embodiments obtained by those skilled in the art based on the embodiments in this application without creative effort are within the scope of protection claimed in this application.

Claims

1. A plate-type air preheater system for mitigating low-temperature blockage and corrosion in rotary air preheaters, comprising a rotary air preheater and a plate-type air preheater assembly connected in sequence, characterized in that, The air inlet of the air preheater system is located at the air inlet of the plate air preheater assembly, and the air outlet is located at the air outlet of the rotary air preheater. The flue gas inlet of the air preheater system is located at the flue gas inlet of the rotary air preheater, and the flue gas outlet of the air preheater system is located at the flue gas outlet of the plate air preheater assembly. The flue gas inlet and outlet of the plate air preheater assembly are equipped with differential pressure transmitters. Multiple independent air ducts are provided in front of the air inlet of the plate air preheater assembly. Switch valves are provided at the air ducts, and the switch valves control multiple valve plates for opening or closing the corresponding air ducts.

2. The plate air preheater system for mitigating low-temperature blockage and corrosion in rotary air preheaters according to claim 1, characterized in that, The plate air preheater assembly includes a first plate air preheater and a second plate air preheater. Air flows sequentially through the air side of the second plate air preheater and the first plate air preheater, and is discharged from the air outlet of the rotary air preheater. Flue gas flows sequentially through the flue gas side of the rotary air preheater and the first plate air preheater, and is discharged from the flue gas outlet of the second plate air preheater.

3. A plate air preheater system for mitigating low-temperature blockage and corrosion in rotary air preheaters according to claim 2, characterized in that, The flue gas side of the first plate air preheater is located below the flue gas side of the rotary air preheater, and the flue gas side of the second plate air preheater is located below the flue gas side of the rotary air preheater.

4. A plate air preheater system for mitigating low-temperature blockage and corrosion in rotary air preheaters according to claim 2, characterized in that, The air inlet of the plate air preheater assembly includes the air inlet of the first plate air preheater and the air inlet of the second plate air preheater. The air duct is located in front of the air inlet of the first plate air preheater, and / or the air duct is located in front of the air inlet of the second plate air preheater.

5. A plate air preheater system for mitigating low-temperature blockage and corrosion in rotary air preheaters according to claim 1, characterized in that, When the switching valve controls multiple valve plates, it closes the corresponding air ducts one by one.

6. A plate air preheater system for mitigating low-temperature blockage and corrosion in rotary air preheaters according to claim 2, characterized in that, The air side between the first plate air preheater and the second plate air preheater is connected by a C-shaped steering chamber.

7. A plate air preheater system for mitigating low-temperature blockage and corrosion in rotary air preheaters according to claim 6, characterized in that, The C-shaped turning chamber is located on the air side of the rotary air preheater in the lateral direction, and multiple independent air ducts are located in the C-shaped turning chamber.

8. A plate air preheater system for mitigating low-temperature blockage and corrosion in rotary air preheaters according to claim 1, characterized in that, The flue gas temperature at the outlet of the rotary air preheater is greater than or equal to 150°C.

9. A plate air preheater system for mitigating low-temperature blockage and corrosion in rotary air preheaters according to claim 1, characterized in that, The switching valve includes a controller for electrical connection with the differential pressure transmitter, so that when the differential pressure transmitter reaches a set threshold, the controller receives a signal and activates the switching valve to close the corresponding air duct.

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