Flue gas denitration system and monitoring method thereof

Abstract

The application provides a flue gas denitration system and a monitoring method thereof. The flow guide heating device comprises a dilution air inlet header tank, at least one inlet header tank branch pipe, at least one flow guide heating structure, at least one outlet header tank branch pipe and a dilution air outlet header tank. Each flow guide heating structure comprises an inlet main pipe, a flow guide heating substructure and an outlet main pipe. For each flow guide heating structure in the flow guide heating device, the following steps are performed: obtaining a first dilution air inlet flow value collected by a dilution air inlet flow meter and a first dilution air outlet flow value collected by a dilution air outlet flow meter; determining whether the difference between the first dilution air inlet flow value and the first dilution air outlet flow value is greater than a preset value; if yes, sequentially checking the flow guide heating substructures in the flow guide heating structure to determine whether the flow guide heating substructures need to be repaired.

Description

Technical Field

[0001] This application relates to the field of flue gas treatment technology, and more specifically, to a flue gas denitrification system and its monitoring method. Background Technology

[0002] SCR (Selective Catalytic Reduction) flue gas denitrification is one of the most widely used and mature NOx control technologies in coal-fired power units. Factors affecting the performance of SCR flue gas denitrification systems include catalyst, flue gas temperature, and flow field distribution. Controlling the flow field in an SCR denitrification system typically involves adding guide vanes at bends and cross-section changes in the flue to effectively mitigate the adverse effects of centrifugal force on the flue gas when passing through bends and inertial forces when passing through cross-section changes, aiming to achieve a uniform flow field distribution at the ammonia injection grid inlet and catalyst inlet.

[0003] If the guide vane wears down to a severe gap, its guiding function will be compromised, leading to a decrease in the uniformity of downstream velocity distribution. On the one hand, in areas with high flow rates, catalyst wear intensifies, shortening catalyst life; in areas with low flow rates, insufficient fly ash carrying capacity leads to catalyst ash accumulation and blockage. On the other hand, there may be excessive ammonia supply to the reducing agent in some areas of the catalyst inlet, while insufficient ammonia supply may occur in others, thereby reducing the overall performance of the denitrification system and increasing operating costs. Currently, the wear condition of the guide vane cannot be monitored in a timely manner during unit operation. Inspection and repair are usually carried out in the flue after the unit is shut down. Therefore, the maintenance of the guide vane is often severely delayed, resulting in significant economic losses and environmental pressure. Summary of the Invention

[0004] The purpose of this application is to provide a flue gas denitrification system and its monitoring method, which can monitor the wear condition of the guide plate in real time, thereby achieving the purpose of stable and reliable flue gas guidance.

[0005] In a first aspect, the present invention provides a monitoring method for a flue gas denitrification system. The flue gas denitrification system includes at least one flow-guiding heating device installed in a flue. The flow-guiding heating device includes a dilution air inlet header, at least one inlet header branch pipe, at least one flow-guiding heating structure, at least one outlet header branch pipe, and a dilution air outlet header. Each flow-guiding heating structure includes an inlet main pipe, at least one flow-guiding heating substructure, and an outlet main pipe. The dilution air inlet header is connected to the inlet main pipe via the inlet header branch pipe, and the dilution air outlet header is connected to the outlet main pipe via the outlet header branch pipe. A dilution air inlet flow meter is installed on the inlet header branch pipe, and a dilution air outlet flow meter is installed on the outlet header branch pipe. For each flow-guiding heating structure in the flow-guiding heating device, the following steps are performed:

[0006] Obtain the first dilution air inlet flow rate value collected by the dilution air inlet flow meter and the first dilution air outlet flow rate value collected by the dilution air outlet flow meter; determine whether the difference between the first dilution air inlet flow rate value and the first dilution air outlet flow rate value is greater than a preset value; if so, check the dilution air heating substructure in the dilution air heating structure in turn to determine whether the dilution air heating substructure needs to be repaired.

[0007] In an optional implementation, each flow-guiding heating substructure includes a flow-guiding heating unit, an inlet flow-guiding branch pipe, an outlet flow-guiding branch pipe, an inlet switch valve, and an outlet switch valve. Each flow-guiding heating unit is connected to a corresponding inlet main pipe through an inlet flow-guiding branch pipe, and each flow-guiding heating unit is connected to a corresponding outlet main pipe through an outlet flow-guiding branch pipe. Each inlet flow-guiding branch pipe is equipped with an inlet switch valve, and each outlet flow-guiding branch pipe is equipped with an outlet switch valve. For each flow-guiding heating substructure, the need for maintenance is determined by: closing the inlet switch valve and the outlet switch valve of the target flow-guiding heating substructure; acquiring the second dilution air inlet flow rate value collected by the dilution air inlet flow meter and the second dilution air outlet flow rate value collected by the dilution air outlet flow meter; determining whether the difference between the second dilution air inlet flow rate value and the second dilution air outlet flow rate value is less than a preset value; if so, the flow-guiding heating unit of the target flow-guiding heating substructure is determined to be worn, and the flow-guiding heating unit is then repaired.

[0008] Secondly, the present invention provides a flue gas denitrification system, the system including a flue and a reactor, wherein at least one flow guiding heating device, an ammonia injection grid, a first flow guiding plate group, a second flow guiding plate group, and a flow straightening grid are provided in the flue.

[0009] In an optional embodiment, the flow guiding and heating device includes a dilution air inlet header, at least one inlet header branch pipe, at least one flow guiding and heating structure, at least one outlet header branch pipe, and a dilution air outlet header. Each flow guiding and heating structure includes an inlet main pipe, at least one flow guiding and heating substructure, and an outlet main pipe. The dilution air inlet header is connected to the inlet main pipe via the inlet header branch pipe, and the dilution air outlet header is connected to the outlet main pipe via the outlet header branch pipe. A dilution air inlet flow meter is installed on the inlet header branch pipe, and a dilution air outlet flow meter is installed on the outlet header branch pipe.

[0010] In an optional embodiment, each flow-guiding heating substructure includes a flow-guiding heating unit, an inlet flow-guiding branch pipe, an outlet flow-guiding branch pipe, an inlet switch valve, and an outlet switch valve. Each flow-guiding heating unit is connected to the corresponding inlet main pipe through the inlet flow-guiding branch pipe, and each flow-guiding heating unit is connected to the corresponding outlet main pipe through the outlet flow-guiding branch pipe. Each inlet flow-guiding branch pipe is equipped with an inlet switch valve, and each outlet flow-guiding branch pipe is equipped with an outlet switch valve.

[0011] In an optional implementation, each flow-guiding heating unit includes a hollow tube and fins symmetrically connected to both sides of the hollow tube.

[0012] In an optional embodiment, the rib is wedge-shaped or rectangular, the height of the rib is 0.4 to 5 times the outer diameter of the hollow tube, and the length of the rib is less than the length of the hollow tube.

[0013] In an optional embodiment, the outer diameter of the hollow tube is 25 mm to 89 mm.

[0014] In an optional implementation, multiple flow-guiding heating substructures are arranged sequentially and form a preset shape.

[0015] In optional implementations, the preset shape is one of a plane, an arc, a combination of plane and arc, or a combination of plane and plane.

[0016] This application provides a flue gas denitrification system and its monitoring method. The flue gas denitrification system includes at least one flow-guiding heating device installed in the flue. The flow-guiding heating device includes a dilution air inlet header, at least one inlet header branch pipe, at least one flow-guiding heating structure, at least one outlet header branch pipe, and a dilution air outlet header. Each flow-guiding heating structure includes an inlet main pipe, a flow-guiding heating substructure, and an outlet main pipe. The dilution air inlet header is connected to the inlet main pipe via the inlet header branch pipe, and the dilution air outlet header is connected to the outlet main pipe via the outlet header branch pipe. A dilution air inlet flow meter is installed on the inlet header branch pipe, and a dilution air outlet flow meter is installed on the outlet header branch pipe. For each flow-guiding heating structure in the flow-guiding heating device, the following steps are performed: obtaining the first dilution air inlet flow rate value collected by the dilution air inlet flow meter and the first dilution air outlet flow rate value collected by the dilution air outlet flow meter; determining whether the difference between the first dilution air inlet flow rate value and the first dilution air outlet flow rate value is greater than a preset value; if so, sequentially checking the flow-guiding heating substructures in the flow-guiding heating structure to determine whether the flow-guiding heating substructure needs maintenance. Real-time monitoring of the wear condition of the flow guiding heating device allows for timely repair and replacement, thereby achieving a stable and reliable flue gas flow guiding effect. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application 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.

[0018] Figure 1 This is a schematic diagram of a flue gas denitrification system provided in an embodiment of this application;

[0019] Figure 2 This is a schematic diagram of the structure of a flow guiding heating device provided in an embodiment of this application;

[0020] Figure 3 This is a partially enlarged view of a flue gas denitrification system provided in an embodiment of this application;

[0021] Figure 4 A flowchart illustrating a method for monitoring a flow-guiding heating structure provided in this application embodiment;

[0022] Figure 5 This is a flowchart illustrating the wear judgment steps of a flow guiding heating device provided in an embodiment of this application.

[0023] icon:

[0024] Flue-1, flow guiding and heating device-2, ammonia injection grid-3, first flow guide plate group-4, second flow guide plate group-5, rectifier grid-6, catalyst-7;

[0025] Dilution air inlet header-201, dilution air inlet flow meter-202, inlet header branch pipe-203, inlet main pipe-204, inlet guide branch pipe-205, inlet switch valve-206, hollow pipe-207a, rib-207b, bolt hole-207c, outlet guide branch pipe-208, outlet switch valve-209, outlet main pipe-210, dilution air outlet flow meter-211, outlet header branch pipe-212, dilution air outlet header-213. Detailed Implementation

[0026] The technical solution of this application is applicable to the SCR flue gas denitrification system on coal-fired power units.

[0027] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0028] Figure 1 This is a schematic diagram of a flue gas denitrification system provided in an embodiment of this application. Figure 1 As shown, the flue gas denitrification system includes a flue and a reactor. The flue is equipped with at least one flow guiding heating device, an ammonia injection grid, a first flow guiding plate group, a second flow guiding plate group, and a flow straightening grid.

[0029] The flue gas flows sequentially through the flow guiding and heating device, the ammonia injection grid, the first flow guiding plate group, the second flow guiding plate group, the rectifier grid, and finally enters the catalyst.

[0030] The flow guiding heating device runs through the bend of the flue.

[0031] Among them, such as Figure 2As shown, the flow guiding and heating device includes a dilution air inlet header, at least one inlet header branch pipe, at least one flow guiding and heating structure, at least one outlet header branch pipe, and a dilution air outlet header. Each flow guiding and heating structure includes an inlet main pipe, at least one flow guiding and heating substructure, and an outlet main pipe. The dilution air inlet header is connected to the inlet main pipe via the inlet header branch pipe, and the dilution air outlet header is connected to the outlet main pipe via the outlet header branch pipe. A dilution air inlet flow meter is installed on the inlet header branch pipe, and a dilution air outlet flow meter is installed on the outlet header branch pipe.

[0032] Each flow-guiding heating substructure includes a flow-guiding heating unit, an inlet flow-guiding branch pipe, an outlet flow-guiding branch pipe, an inlet switch valve, and an outlet switch valve. Each flow-guiding heating unit is connected to the corresponding inlet main pipe through the inlet flow-guiding branch pipe, and each flow-guiding heating unit is connected to the corresponding outlet main pipe through the outlet flow-guiding branch pipe. Each inlet flow-guiding branch pipe is equipped with an inlet switch valve, and each outlet flow-guiding branch pipe is equipped with an outlet switch valve.

[0033] Each flow-guiding heating unit includes a hollow tube and fins symmetrically connected to both sides of the hollow tube. The fins are wedge-shaped or rectangular, with a height of 0.4 to 5 times the outer diameter of the hollow tube and a length less than the length of the hollow tube. The outer diameter of the hollow tube ranges from 25 mm to 89 mm.

[0034] Multiple flow-guiding heating substructures are arranged sequentially to form a preset shape. The preset shape can be one of a plane, an arc surface, a combination of plane and arc surface, or a combination of plane and plane.

[0035] In one specific embodiment, such as Figure 3 As shown, the flow guiding heating device comprises three flow guiding heating structures, each consisting of 11 flow guiding heating substructures arranged sequentially to form a preset shape. Viewed from the front, the preset shape is a combination of an arc surface with a radius of 2m and an angle of 45°, and a straight surface with a length of 0.35m along the flue gas flow direction. Each flow guiding heating unit consists of a hollow tube 207a and two identical ribs 207b symmetrically welded to both sides of the hollow tube. The hollow tube 207a has a specification of Ф57×3. The included angle between the two ribs 207b on the hollow tube 207a is 160°~180°, and both have a thickness of 6mm and a height of 59mm.

[0036] The flow guiding heating unit can pass horizontally through the SCR flue gas denitrification flue and be fixed to the outer wall of the SCR flue gas denitrification flue through the bolt holes at both ends of the two side ribs.

[0037] After adopting the flow-guiding heating device, numerical simulation calculations show that the upstream velocity of the ammonia injection grid is uniformly distributed under high, medium, and low load conditions, with a relative standard deviation of less than 15%. This achieves good flue gas flow guidance and avoids the problem of flue gas concentrating to the right after passing through a bend. Thermodynamic calculations show that the dilution air outlet temperature is 248℃ under high load conditions and 185℃ under low load conditions, meeting the requirement that the heated dilution air temperature is not lower than 180℃.

[0038] Figure 4 A flowchart illustrating a method for monitoring a flow-guiding heating structure provided in an embodiment of this application. Figure 4 As shown in the embodiment of this application, a method for monitoring a flow-guiding heating structure is provided, applicable to the controller of a flue gas denitrification system. For each flow-guiding heating structure in the flow-guiding heating device, the following steps are performed:

[0039] S1. Obtain the first dilution air inlet flow rate value collected by the dilution air inlet flow meter and the first dilution air outlet flow rate value collected by the dilution air outlet flow meter;

[0040] S2. Determine whether the difference between the inlet flow rate of the first dilution air and the outlet flow rate of the first dilution air is greater than a preset value;

[0041] S3. If so, then the flow guiding heating substructure in the flow guiding heating structure shall be investigated to determine whether the flow guiding heating substructure needs to be repaired.

[0042] This application provides a monitoring method for a flue gas denitrification system, which monitors the wear condition of the flow guiding heating device in real time, and repairs or replaces it in a timely manner, thereby achieving a stable and reliable flue gas flow guiding effect.

[0043] like Figure 5 As shown, the wear judgment method of the flow guiding heating device of the flue gas denitrification system provided in this application specifically includes:

[0044] S3000: Obtain the first dilution air inlet flow rate value collected by the dilution air inlet flow meter and the first dilution air outlet flow rate value collected by the dilution air outlet flow meter;

[0045] S3002. Determine whether the difference between the first dilution air inlet flow rate and the first dilution air outlet flow rate is greater than a preset value;

[0046] S3004. If so, then close the inlet and outlet switch valves of the target flow guiding heating substructure.

[0047] S3006. Obtain the second dilution air inlet flow rate value collected by the dilution air inlet flow meter and the second dilution air outlet flow rate value collected by the dilution air outlet flow meter;

[0048] S3008. Determine whether the difference between the second dilution air inlet flow rate and the second dilution air outlet flow rate is less than a preset value;

[0049] S3010. If so, it is determined that the flow heating unit of the target flow heating substructure is worn and needs to be repaired.

[0050] In a specific embodiment, the readings of the dilution air inlet flow meter and the dilution air outlet flow meter can be checked. When the deviation between the two reaches 3%, the wear and leakage of the flow guiding heating substructure can be judged and repaired in the following manner.

[0051] Close the inlet and outlet valves of the flow guiding and heating substructure, and check the reading deviation of the dilution air inlet and outlet flow meters again. If the reading deviation is still above 3%, the flow guiding and heating unit has no obvious wear or air leakage. If the reading deviation drops to within 3%, the flow guiding and heating unit has severe wear and air leakage. Loosen the fixings at both ends of the fins and the connections at both ends of the hollow tube of the flow guiding and heating unit, pull the flow guiding and heating unit out of the flue for inspection, replace or repair the worn parts, and then put the flow guiding and heating unit back into its original position in the flue and fix it in place to restore its flow guiding and heating function.

[0052] In the embodiments provided in this application, it should be understood that the disclosed apparatus 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 displayed 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.

[0053] Furthermore, 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.

[0054] Furthermore, the functional modules in the various embodiments of this application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0055] It should be noted that if the function is implemented as a software module and sold or used as an independent product, it can be stored in a 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 part 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, a server, or a 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.

[0056] In this document, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, without necessarily requiring or implying any such actual relationship or order between these entities or operations.

[0057] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A monitoring method for a flue gas denitrification system, characterized in that, The flue gas denitrification system includes at least one flow-guiding heating device installed in the flue. Each flow-guiding heating device includes a dilution air inlet header, at least one inlet header branch pipe, at least one flow-guiding heating structure, at least one outlet header branch pipe, and a dilution air outlet header. Each flow-guiding heating structure includes an inlet main pipe, at least one flow-guiding heating substructure, and an outlet main pipe. The dilution air inlet header is connected to the inlet main pipe via the inlet header branch pipe, and the dilution air outlet header is connected to the outlet main pipe via the outlet header branch pipe. A dilution air inlet flow meter is installed on the inlet header branch pipe, and a dilution air outlet flow meter is installed on the outlet header branch pipe. For each flow guiding heating structure in the flow guiding heating device, perform the following steps: Acquire the first dilution air inlet flow rate value collected by the dilution air inlet flow meter and the first dilution air outlet flow rate value collected by the dilution air outlet flow meter; Determine whether the difference between the first dilution air inlet flow rate and the first dilution air outlet flow rate is greater than a preset value; If so, the flow-guiding heating substructures in the flow-guiding heating structure will be checked one by one to determine whether the flow-guiding heating substructure needs to be repaired.

2. The method according to claim 1, characterized in that, Each flow-guiding heating substructure includes a flow-guiding heating unit, an inlet flow-guiding branch pipe, an outlet flow-guiding branch pipe, an inlet switch valve, and an outlet switch valve. Each flow-guiding heating unit is connected to a corresponding inlet main pipe through an inlet flow-guiding branch pipe, and each flow-guiding heating unit is connected to a corresponding outlet main pipe through an outlet flow-guiding branch pipe. Each inlet flow-guiding branch pipe is equipped with an inlet switch valve, and each outlet flow-guiding branch pipe is equipped with an outlet switch valve. For each flow-guiding heating substructure, determine whether the flow-guiding heating substructure requires maintenance using the following methods: Close the inlet and outlet valves of the target flow-guiding heating substructure; Acquire the second dilution air inlet flow rate value collected by the dilution air inlet flow meter and the second dilution air outlet flow rate value collected by the dilution air outlet flow meter; Determine whether the difference between the second dilution air inlet flow rate and the second dilution air outlet flow rate is less than a preset value; If so, it is determined that the flow-guiding heating unit of the target flow-guiding heating substructure is worn and needs to be repaired.

3. A flue gas denitrification system, characterized in that, A monitoring method applicable to the flue gas denitrification system according to claim 1 or 2, wherein the system includes a flue and a reactor, and at least one flow guiding heating device, an ammonia injection grid, a first flow guiding plate group, a second flow guiding plate group, and a flow straightening grid are provided in the flue.

4. The system according to claim 3, characterized in that, The flow guiding and heating device includes a dilution air inlet header, at least one inlet header branch pipe, at least one flow guiding and heating structure, at least one outlet header branch pipe, and a dilution air outlet header. Each flow guiding and heating structure includes an inlet main pipe, at least one flow guiding and heating substructure, and an outlet main pipe. The dilution air inlet header is connected to the inlet main pipe via an inlet header branch pipe, and the dilution air outlet header is connected to the outlet main pipe via an outlet header branch pipe. A dilution air inlet flow meter is installed on the inlet header branch pipe, and a dilution air outlet flow meter is installed on the outlet header branch pipe.

5. The system according to claim 4, characterized in that, Each flow-guiding heating substructure includes a flow-guiding heating unit, an inlet flow-guiding branch pipe, an outlet flow-guiding branch pipe, an inlet switch valve, and an outlet switch valve. Each flow-guiding heating unit is connected to the corresponding inlet main pipe through the inlet flow-guiding branch pipe, and each flow-guiding heating unit is connected to the corresponding outlet main pipe through the outlet flow-guiding branch pipe. Each inlet flow-guiding branch pipe is equipped with an inlet switch valve, and each outlet flow-guiding branch pipe is equipped with an outlet switch valve.

6. The system according to claim 5, characterized in that, Each flow-guiding heating unit includes a hollow tube and fins symmetrically connected to both sides of the hollow tube.

7. The system according to claim 6, characterized in that, The ribs are wedge-shaped or rectangular, with a height of 0.4 to 5 times the outer diameter of the hollow tube and a length less than the length of the hollow tube.

8. The system according to claim 6, characterized in that, The outer diameter of the hollow tube is 25mm to 89mm.

9. The system according to claim 6, characterized in that, Multiple flow-guiding heating substructures are arranged sequentially to form a preset shape.

10. The system according to claim 9, characterized in that, The preset shape is one of a plane, an arc, a combination of plane and arc, or a combination of plane and plane.

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