Flue gas denitration system and monitoring method thereof

Abstract

The invention provides a flue gas denitration system and a monitoring method thereof.The flow guide heating device comprises a dilution air inlet header, at least one inlet header branch pipe, at least one flow guide heating structure, at least one outlet header branch pipe and a dilution air outlet header, and each flow guide heating structure comprises an inlet main pipe, a flow guide heating substructure and an outlet main pipe; for each diversion heating structure in the diversion heating device, the following steps are executed: obtaining a first dilution air inlet flow value collected by a dilution air inlet flowmeter and a first dilution air outlet flow value collected by a dilution air outlet flowmeter; whether the difference value between the first dilution air inlet flow value and the first dilution air outlet flow value is larger than a preset value or not is determined; if yes, flow guide heating substructures in the flow guide heating structure are checked in sequence, so that whether the flow guide heating substructures need to be maintained or not is determined.

Description

Technical Field

[0001] The present application relates to the technical field of flue gas treatment, and in particular to a flue gas denitrification system and a monitoring method thereof. Background Art

[0002] SCR flue gas denitrification is one of the NOx control technologies with the most application achievements and the most mature technology in coal-fired units. Factors affecting the performance of SCR flue gas denitrification systems include catalysts, flue gas temperature and flow field distribution. The control of the flow field of the SCR denitrification system usually adopts the method of adding guide plates at the turns and variable cross-sections of the flue to fully weaken the adverse effects of centrifugal force and inertia of the flue gas when passing through the bends, so as to achieve uniform distribution of the flow field at the inlet of the ammonia injection grid and the inlet of the catalyst.

[0003] If the guide plate is worn and has serious gaps, the guide function will be destroyed, which will cause the downstream velocity distribution uniformity to deteriorate. On the one hand, the catalyst wear in the high velocity area will be aggravated, resulting in a shortened catalyst life, and the flue gas in the low velocity area will have insufficient fly ash carrying capacity, resulting in catalyst ash accumulation and blockage. On the other hand, there will be excessive supply of reducing agent ammonia in some areas of the catalyst inlet and insufficient supply of reducing agent ammonia in some areas, thereby reducing the overall performance of the denitrification system and increasing operating costs. At present, the wear condition of the guide plate cannot be timely grasped during the operation of the unit. Usually, the unit is shut down before entering the flue for inspection and repair. Therefore, there is often a serious lag in the maintenance of the guide plate, and the economic losses and environmental pressure during the period are huge. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a flue gas denitrification system and a monitoring method thereof, so as to monitor the wear condition of the guide plate in real time, thereby achieving the purpose of stable and reliable flue gas diversion.

[0005] In a first aspect, the present invention provides a monitoring method for a flue gas denitration system, wherein the flue gas denitration system comprises at least one flow guiding and heating device arranged in a flue, the flow guiding and heating device comprises 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 comprises an inlet main pipe, at least one flow guiding and heating substructure, and an outlet main pipe, wherein the dilution air inlet header is connected to the inlet main pipe through the inlet header branch pipe, the dilution air outlet header is connected to the outlet main pipe through the outlet header branch pipe, a dilution air inlet flow meter is arranged on the inlet header branch pipe, and a dilution air outlet flow meter is arranged on the outlet header branch pipe, and the following steps are performed for each flow guiding and heating structure in the flow guiding and heating device:

[0006] Obtain a first dilution air inlet flow value collected by the dilution air inlet flowmeter and a first dilution air outlet flow value collected by the dilution air outlet flowmeter; determine 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 so, check the diversion heating substructures in the diversion heating structure in turn to determine whether the diversion heating substructure needs to be repaired.

[0007] In an optional embodiment, each diversion heating substructure includes a diversion heating unit, an inlet diversion branch pipe, an outlet diversion branch pipe, an inlet switch valve, and an outlet switch valve. Each diversion heating unit is connected to the corresponding inlet main pipe through the inlet diversion branch pipe, and each diversion heating unit is connected to the corresponding outlet main pipe through the outlet diversion branch pipe. Each inlet diversion branch pipe is provided with an inlet switch valve, and each outlet diversion branch pipe is provided with an outlet switch valve. For each diversion heating substructure, determine whether the diversion heating substructure needs maintenance in the following manner: close the inlet switch valve and the outlet switch valve of the target diversion heating substructure; obtain the second dilution air inlet flow value collected by the dilution air inlet flowmeter and the second dilution air outlet flow value collected by the dilution air outlet flowmeter; determine whether the difference between the second dilution air inlet flow value and the second dilution air outlet flow value is less than a preset value; if so, determine that the diversion heating unit of the target diversion heating substructure is worn, so as to repair the diversion heating unit.

[0008] In a second aspect, the present invention provides a flue gas denitrification system, the system comprising a flue and a reactor, wherein at least one guide heating device, an ammonia injection grid, a first guide plate group, a second guide plate group, and a rectifying grid are arranged in the flue.

[0009] In an optional embodiment, the diversion heating device includes a dilution air inlet header, at least one inlet header branch, at least one diversion heating structure, at least one outlet header branch and a dilution air outlet header, each diversion heating structure includes an inlet main pipe, at least one diversion heating substructure and an outlet main pipe, wherein the dilution air inlet header is connected to the inlet main pipe via an inlet header branch, the dilution air outlet header is connected to the outlet main pipe via an outlet header branch, a dilution air inlet flowmeter is provided on the inlet header branch, and a dilution air outlet flowmeter is provided on the outlet header branch.

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

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

[0012] In an optional embodiment, the fin is wedge-shaped or rectangular, the height of the fin is 0.4 to 5 times the outer diameter of the hollow tube, and the length of the fin 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 embodiment, a plurality of flow-conducting heating substructures are arranged in sequence to form a preset shape.

[0015] In an optional embodiment, the preset shape is one of a plane, a curved surface, a combination of a plane and a curved surface, or a combination of a plane and a plane.

[0016] The present application provides a flue gas denitrification system and a monitoring method thereof, the flue gas denitrification system includes at least one diversion heating device arranged in a flue, the diversion heating device includes a dilution air inlet header, at least one inlet header branch pipe, at least one diversion heating structure, at least one outlet header branch pipe and a dilution air outlet header, each diversion heating structure includes an inlet main pipe, a diversion heating substructure, and an outlet main pipe, wherein the dilution air inlet header is connected to the inlet main pipe through the inlet header branch pipe, the dilution air outlet header is connected to the outlet main pipe through the outlet header branch pipe, a dilution air inlet flowmeter is arranged on the inlet header branch pipe, and a dilution air outlet flowmeter is arranged on the outlet header branch pipe, and for each diversion heating structure in the diversion heating device, the following steps are performed: obtaining a first dilution air inlet flow value collected by the dilution air inlet flowmeter and a first dilution air outlet flow value collected by the dilution air outlet flowmeter; 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 so, checking the diversion heating substructures in the diversion heating structure in turn to determine whether the diversion heating substructure needs to be repaired. Monitor the wear condition of the diversion heating device in real time, and perform repairs and replacements in time to achieve a stable and reliable flue gas diversion effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A schematic diagram of the structure of a flue gas denitrification system provided in an embodiment of the present application;

[0019] Figure 2 A schematic structural diagram of a flow-conducting heating device provided in an embodiment of the present application;

[0020] Figure 3 A partially enlarged view of a flue gas denitrification system provided in an embodiment of the present application;

[0021] Figure 4 A flow chart of a method for monitoring a flow-conducting heating structure provided in an embodiment of the present application;

[0022] Figure 5 A flowchart of the wear judgment steps of a flow-conducting heating device provided in an embodiment of the present application.

[0023] icon:

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

[0025] Dilution air inlet manifold -201, dilution air inlet flowmeter -202, inlet manifold branch pipe -203, inlet main pipe -204, inlet diversion branch pipe -205, inlet switch valve -206, hollow pipe -207a, rib -207b, bolt hole -207c, outlet diversion branch pipe -208, outlet switch valve -209, outlet main pipe -210, dilution air outlet flowmeter -211, outlet manifold branch pipe -212, dilution air outlet manifold -213. DETAILED DESCRIPTION

[0026] The technical solution of the present application is applicable to the SCR flue gas denitrification system of a coal-fired unit.

[0027] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0028] Figure 1 This is a schematic diagram of the structure of a flue gas denitrification system provided in an embodiment of the present application. Figure 1 As shown, the flue gas denitrification system includes a flue and a reactor, and at least one guide heating device, an ammonia injection grid, a first guide plate group, a second guide plate group, and a rectifying grid are arranged in the flue.

[0029] The flue gas flows through the guide heating device, the ammonia injection grid, the first guide plate group, the second guide plate group, the rectifying grid in sequence, and finally enters the catalyst.

[0030] The diversion heating device runs through the elbow of the flue.

[0031] Among them, Figure 2As shown, the diversion heating device includes a dilution air inlet header, at least one inlet header branch pipe, at least one diversion heating structure, at least one outlet header branch pipe and a dilution air outlet header, each diversion heating structure includes an inlet main pipe, at least one diversion heating substructure, and an outlet main pipe, wherein the dilution air inlet header is connected to the inlet main pipe through the inlet header branch pipe, the dilution air outlet header is connected to the outlet main pipe through the outlet header branch pipe, a dilution air inlet flowmeter is provided on the inlet header branch pipe, and a dilution air outlet flowmeter is provided on the outlet header branch pipe.

[0032] Each diversion heating substructure includes a diversion heating unit, an inlet diversion branch pipe, an outlet diversion branch pipe, an inlet switch valve, and an outlet switch valve. Each diversion heating unit is connected to the corresponding inlet mother pipe through the inlet diversion branch pipe, and each diversion heating unit is connected to the corresponding outlet mother pipe through the outlet diversion branch pipe. Each inlet diversion branch pipe is provided with an inlet switch valve, and each outlet diversion branch pipe is provided with an outlet switch valve.

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

[0034] The plurality of flow-guiding heating substructures are arranged in sequence to form a preset shape, which is one of a plane, a curved surface, a combination of a plane and a curved surface, or a combination of a plane and a plane.

[0035] In a specific embodiment, if Figure 3 As shown, the flow-conducting heating device includes three flow-conducting heating structures, and each flow-conducting heating structure is formed into a preset shape by 11 flow-conducting heating substructures arranged in sequence. Seen 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-conducting heating unit consists of a hollow tube 207a and two identical fins 207b symmetrically welded on both sides of the hollow tube. The specification of the hollow tube 207a is Ф57×3. The angle between the two fins 207b on the hollow tube 207a is 160°~180°, and the thickness is 6mm and the height is 59mm.

[0036] The guide heating unit can penetrate the SCR flue gas denitrification duct horizontally and be fixed on the outer wall of the SCR flue gas denitrification duct through the bolt holes at both ends of the ribs on both sides.

[0037] After adopting the diversion heating device, numerical simulation calculation shows that the velocity upstream of the ammonia injection grid is evenly distributed under high, medium and low load conditions, and the relative standard deviation is less than 15%, achieving good flue gas diversion and avoiding the problem of flue gas concentration to the right after passing through the bend. According to thermal calculation, the dilution air outlet temperature is 248℃ under high load conditions and 185℃ under low load conditions, meeting the requirement that the dilution air temperature after heating is not less than 180℃.

[0038] Figure 4 A flow chart of a method for monitoring a flow-conducting heating structure provided in an embodiment of the present application. Figure 4 As shown, a method for monitoring a flow-conducting heating structure provided in an embodiment of the present application is applicable to a controller of a flue gas denitration system, and for each flow-conducting heating structure in a flow-conducting heating device, the following steps are performed:

[0039] S1. Obtain 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;

[0040] S2, 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;

[0041] S3. If yes, then the flow-conducting heating substructure in the flow-conducting heating structure is checked to determine whether the flow-conducting heating substructure needs to be repaired.

[0042] The present application provides a monitoring method for a flue gas denitrification system, which monitors the wear condition of a diversion heating device in real time, performs timely repairs and replacements, and thereby can achieve a stable and reliable flue gas diversion effect.

[0043] like Figure 5 As shown, the present application provides a method for judging the wear of a guide heating device of a flue gas denitration system, which specifically includes:

[0044] S3000, 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;

[0045] S3002, 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;

[0046] S3004: If yes, close the inlet switch valve and the outlet switch valve of the target diversion heating substructure;

[0047] S3006, obtaining a second dilution air inlet flow value collected by a dilution air inlet flow meter and a second dilution air outlet flow value collected by a dilution air outlet flow meter;

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

[0049] S3010: If yes, it is determined that the flow-guiding heating unit of the target flow-guiding heating substructure is worn out 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 guide heating substructure are judged and repaired in the following manner.

[0051] Close the inlet switch valve and outlet switch valve of the diversion heating substructure, and check the indication deviation of the dilution air inlet flowmeter and the dilution air outlet flowmeter again. If the indication deviation is still above 3%, the diversion heating unit has no obvious wear and leakage. If the indication deviation drops to less than 3%, the diversion heating unit has serious wear and leakage. Loosen the fixation of the two ends of the fins of the diversion heating unit and the connection of the two ends of the hollow tube, pull the diversion heating unit out of the flue for inspection, replace or repair the worn parts, put the diversion heating unit into the original position of the flue and fix it to restore its diversion heating effect.

[0052] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0053] In addition, the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

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

[0055] It should be noted that if the function is implemented in the form of a software function 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 the present application can essentially be embodied in the form of a software product, or the part that contributes to the prior art or the part of the technical solution. The computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM) random access memory (RAM), disk or optical disk, and other media that can store program codes.

[0056] In this document, relational terms such as first and second, etc. are used merely to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0057] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for monitoring a flue gas denitrification system, characterized in that: The flue gas denitration system comprises at least one flow guiding and heating device arranged in the flue, the flow guiding and heating device comprises 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 comprises an inlet main pipe, at least one flow guiding and heating substructure and an outlet main pipe, wherein the dilution air inlet header is connected to the inlet main pipe through the inlet header branch pipe, the dilution air outlet header is connected to the outlet main pipe through the outlet header branch pipe, a dilution air inlet flow meter is arranged on the inlet header branch pipe, and a dilution air outlet flow meter is arranged on the outlet header branch pipe, For each flow-conducting heating structure in the flow-conducting heating device, perform the following steps: Obtain 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; Determine 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 so, the flow-conducting heating substructures in the flow-conducting heating structure are checked in turn to determine whether the flow-conducting heating substructures need to be repaired.

2. The method according to claim 1, characterized in that Each diversion heating substructure includes a diversion heating unit, an inlet diversion branch pipe, an outlet diversion branch pipe, an inlet switch valve, and an outlet switch valve. Each diversion heating unit is connected to the corresponding inlet main pipe through the inlet diversion branch pipe, and each diversion heating unit is connected to the corresponding outlet main pipe through the outlet diversion branch pipe. Each inlet diversion branch pipe is provided with an inlet switch valve, and each outlet diversion branch pipe is provided with an outlet switch valve. For each diversion heating substructure, determine whether the diversion heating substructure needs maintenance by the following methods: Closing the inlet switch valve and the outlet switch valve of the target diversion heating substructure; Obtain a second dilution air inlet flow value collected by a dilution air inlet flow meter and a second dilution air outlet flow value collected by a dilution air outlet flow meter; Determine whether the difference between the second dilution air inlet flow value and the second dilution air outlet flow value 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 the flow-guiding heating unit needs to be repaired.

3. A flue gas denitrification system, characterized in that: The system comprises a flue and a reactor, wherein at least one guide heating device, an ammonia injection grid, a first guide plate group, a second guide plate group and a rectifying grid are arranged in the flue.

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

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

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

7. The system according to claim 6, characterized in that The fins are wedge-shaped or rectangular, the height of the fins is 0.4 to 5 times the outer diameter of the hollow tube, and the length of the fins is 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 25 mm to 89 mm.

9. The system according to claim 6, characterized in that A plurality of flow-guiding heating substructures are arranged in sequence to form a preset shape.

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

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