An ammonia nozzle and method based on instantaneous automatic adjustment of flue gas flow rate

Abstract

The application provides an ammonia nozzle and a method for instant automatic adjustment based on flue gas flow rate. The ammonia nozzle comprises a shell, both ends of which are open and a vane is arranged on the opposite side of a gas outlet. Ammonia gas flows into the shell and is sprayed through the gas outlet. Flue gas is sprayed on the vane through the peripheral side of the shell. An adjusting shaft is arranged, which comprises a rotating shaft, an elastic member and an adjusting opening. One end of the rotating shaft extends into the shell, and the other end is connected with the vane. The elastic member is fixed in the shell and connected with the rotating shaft. Fixed switch blades and rotating switch blades connected with the rotating shaft are arranged in the shell, and air outlets are arranged on the fixed switch blades and the rotating switch blades. When the rotating switch blades rotate with the rotating shaft, part of the air outlets is shielded. The remaining air outlets form the adjusting opening through which the ammonia gas flows. The opening degree of the adjusting opening is positively correlated with the rotating displacement amount of the vane. The ammonia nozzle can automatically and instantaneously adjust the ammonia spraying amount according to the fluctuation of the flue gas flow rate, so as to achieve the purpose that the ammonia spraying amount is timely matched with the flue gas flow rate.

Description

Technical Field

[0001] This application relates to the field of flue gas purification in thermal power plants, and in particular to an ammonia nozzle and method based on real-time automatic adjustment of flue gas flow rate. Background Technology

[0002] Currently, most thermal power plants use SCR (Selective Catalytic Reduction) denitrification devices, which employ ammonia gas as a reducing agent injected into the flue. The ammonia gas reacts with nitrogen oxides on the catalyst surface to remove nitrogen oxides from the flue gas. In SCR denitrification devices, ammonia gas is injected into the flue gas under pressure through ammonia injection grid and nozzles. Both the ammonia injection grid and nozzles are fixed steel structures and cannot adjust the amount of ammonia injected internally according to changes in the external flue gas velocity. However, in reality, due to factors such as fuel and combustion method, the boiler's combustion conditions cannot be absolutely stable, and therefore the flue gas velocity, as a combustion product, fluctuates constantly.

[0003] In this situation, during actual SCR operation, a phenomenon generally occurs where the nitrogen oxide concentration in the flue gas duct cross-section is relatively uniform, but the flow velocity distribution is uneven. Fluctuations in flow velocity directly lead to a mismatch between the injected ammonia volume and the actual ammonia demand, resulting in either excessive or insufficient injection. Excessive SCR ammonia injection causes severe ammonium bisulfate deposition in the downstream air preheater, clogging the flow channels of the heat exchange elements and significantly increasing the air preheater's operating resistance, severely impacting the safety and stability of boiler operation. Insufficient ammonia injection, on the other hand, leads to insufficient nitrogen oxide emission reduction, resulting in excessive nitrogen oxide emissions.

[0004] Currently, to address the issues of over- or under-injection, related technologies employ a strategy of precise ammonia injection control. This involves monitoring the concentration of nitrogen oxides at the denitrification outlet using instruments and controlling the ammonia injection amount at the denitrification inlet based on feedback. While this control method has some effectiveness, improving ammonia injection mismatch over a large timescale, it suffers from a significant drawback: a substantial time delay between measurement and adjustment. From the start of measurement to data output, there is typically a delay of tens of seconds to several minutes (depending on the measurement principle and sampling system). By the time adjustment is made, a considerable amount of time has passed, and the boiler's operating conditions have fluctuated repeatedly. The actual operating conditions at the time of adjustment are no longer those at the time of measurement. This method of measuring first and then adjusting often fails to achieve truly timely, effective, and precise ammonia injection. Therefore, providing an ammonia nozzle and injection method based on real-time automatic adjustment of flue gas velocity, enabling the nozzle to automatically and instantly adjust the ammonia injection amount according to fluctuations in flue gas velocity, to achieve timely ammonia injection matching with the flue gas velocity, is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] This application aims to at least partially address one of the technical problems in the related art.

[0006] Therefore, the purpose of this application is to propose an ammonia nozzle and ammonia injection method based on real-time automatic adjustment of flue gas velocity. The ammonia nozzle can automatically and instantly adjust the amount of ammonia injected according to the fluctuation of flue gas velocity, so as to achieve the purpose of timely matching of the amount of ammonia injected with the flue gas velocity.

[0007] To achieve the above objectives, this application proposes an ammonia nozzle that automatically adjusts flue gas flow rate in real time, comprising:

[0008] A casing; an impeller is disposed on the opposite side of the outlet, open at both ends; ammonia gas flows into the casing and is injected through the outlet; flue gas is injected onto the impeller through the periphery of the casing; and

[0009] An adjusting shaft assembly includes a rotating shaft, an elastic element, and an adjusting opening. One end of the rotating shaft extends into the housing, and the other end is connected to the impeller. The elastic element is fixed within the housing and connected to the rotating shaft. Air outlets are provided on both a fixed switch plate within the housing and a rotating switch plate whose center is connected to the rotating shaft. When the rotating switch plate rotates with the rotating shaft, it partially blocks the air outlets. The remaining air outlets form the adjusting opening through which ammonia airflow passes. The opening degree of the adjusting opening is positively correlated with the rotational displacement of the impeller.

[0010] In some embodiments, the fixed switch piece is fixed inside the housing, and a bearing is connected between the middle part of the fixed switch piece and the rotating shaft. The fixed switch piece includes a first baffle, which is half of the area of ​​the fixed switch piece. The air outlet is the other half of the area of ​​the fixed switch piece.

[0011] In some embodiments, the fixed switch piece is a circular piece structure with a diameter adapted to the inner diameter of the housing; the first baffle is a semi-circular structure.

[0012] In some embodiments, the rotary switch piece is fixedly connected to the rotating shaft and includes a second baffle, the second baffle being half the area of ​​the rotary switch piece; wherein the air outlet is the other half of the area of ​​the fixed switch piece.

[0013] In some embodiments, the rotary switch piece is a circular piece with a diameter adapted to the inner diameter of the housing; the second baffle is a semi-circular structure.

[0014] In some embodiments, the fixed switch piece and the rotary switch piece have the same structure and diameter.

[0015] In some embodiments, the elastic element includes a spring and a metal wire; the two ends of the spring are respectively connected to the inner wall of the housing and the metal wire, the metal wire is disposed on the rotating shaft, and when the rotating shaft rotates, the metal wire is wound around the rotating shaft and stretches the spring.

[0016] In some embodiments, the rotating shaft is disposed within the housing via a bracket, and the bracket and the rotating shaft are connected by a bearing; the extending direction of the rotating shaft coincides with the central axis direction of the housing.

[0017] In some embodiments, the air outlet of the housing is a tapered funnel shape, and the radius of the air outlet corresponding to the middle part of the impeller is smaller than the blade length of the impeller.

[0018] According to a second aspect of this application, a method for real-time automatic adjustment of flue gas flow rate is proposed, utilizing the ammonia nozzle described in any of the above embodiments, comprising:

[0019] Under stable operating conditions: Ammonia gas flows into the housing and is sprayed onto the impeller through the outlet, causing the impeller to rotate; as the impeller rotates, the rotating shaft rotates and the elastic element is wound and stretched until the torsional force generated by the impeller is balanced with the tension of the elastic element; the rotating shaft stops rotating; the ammonia gas flows through the adjustment opening formed by the rotating switch plate and the fixed switch plate and is sprayed out from the outlet;

[0020] When the operating conditions fluctuate, the change in the rotational displacement of the impeller alters the rotational angle of the rotating shaft. The opening of the adjustment opening is adjusted according to the rotational angle of the rotating shaft, wherein the opening of the adjustment opening is positively correlated with the rotational displacement of the impeller.

[0021] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0022] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0023] Figure 1 This is a schematic diagram of an ammonia nozzle based on real-time automatic adjustment of flue gas flow rate according to an embodiment of this application;

[0024] Figure 2 This is a schematic diagram of the structure of a rotary switch piece and a fixed switch piece according to an embodiment of this application;

[0025] Figure 3 This is a schematic diagram of the impeller structure according to an embodiment of this application;

[0026] Figure 4 This is a schematic diagram of an ammonia nozzle based on real-time automatic adjustment of flue gas flow rate, as proposed in an embodiment of this application.

[0027] In the diagram, 1 is the housing; 2 is the rotating shaft; 3 is the spring; 4 is the metal wire; 5 is the bracket; 6 is the first bearing; 7 is the fixed switch piece; 8 is the second bearing; 9 is the rotary switch piece; and 10 is the impeller. Detailed Implementation

[0028] Embodiments of this application are described in detail below. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Rather, embodiments of this application include all variations, modifications, and equivalents falling within the spirit and scope of the appended claims.

[0029] See Figures 1-4 To achieve the above objectives, this application proposes an ammonia nozzle with real-time automatic adjustment based on flue gas flow rate, comprising a housing 1 and an adjusting shaft; the housing 1 is open at both ends, and an impeller 10 is arranged on the opposite side of the outlet; ammonia gas flows into the housing 1 and is injected through the outlet; flue gas is injected onto the impeller 10 through the periphery of the housing 1. In other words, the housing 1 is a hollow shell structure with open ends, the two open ends being the inlet and outlet, wherein the ammonia gas flows horizontally from the inlet to the outlet and is ejected from the outlet, wherein the impeller 10 is arranged on the opposite side of the outlet, the two are arranged opposite each other and separated by a certain horizontal distance, and the outlet is a gradually narrowing funnel shape, so that the ammonia gas flow gradually gathers. An example is shown below. Figures 1-2 As shown, the central axis of the outlet coincides with the center of the impeller 10; simultaneously, the radius of the outlet is smaller than the blade length of the impeller 10, ensuring that the ammonia gas flow ejected from the outlet is expelled and preventing the ammonia gas flow itself from driving the impeller 10 to rotate. The impeller 10 is as follows... Figure 3 As shown.

[0030] The adjusting shaft includes a rotating shaft 2, an elastic element, and an adjusting opening; one end of the rotating shaft 2 extends into the housing 1, and the other end is connected to the impeller 10; the elastic element is fixed inside the housing 1 and connected to the rotating shaft 2; both the fixed switch plate 7 inside the housing 1 and the rotating switch plate 9 connected to the center of the rotating shaft 2 are provided with air outlets; the rotating switch plate 9 partially blocks the air outlets when rotating with the rotating shaft 2; the remaining air outlets form an adjusting opening through which ammonia air flows; the opening degree of the adjusting opening is positively correlated with the rotational displacement of the impeller 10.

[0031] In other words, one end of the rotating shaft 2 extends into the housing 1, and the other end extends out of the housing 1 and is connected to the impeller 10 outside the housing 1. The rotating shaft 2 passes through the middle of the impeller 10, and the two are fixed together. When flue gas is ejected from both sides of the housing 1, driving the impeller 10 to rotate, the rotation of the impeller 10 can drive the rotating shaft 2 to rotate. An example is shown below. Figure 4 The rotating shaft 2 shown is mounted inside the housing 1 via a bracket 5, and the bracket 5 and the rotating shaft 2 are connected by a first bearing 6; the extending direction of the rotating shaft 2 coincides with the central axis direction of the housing 1.

[0032] In this embodiment, a fixed switch piece 7 and a rotary switch piece 9 are disposed in the middle of the rotating shaft 2 inside the housing 1. The rotating shaft 2 passes through the middle of the fixed switch piece 7 and the rotary switch piece 9 in sequence. The fixed switch piece 7 and the rotary switch piece 9 are tightly fitted without gaps. The fixed switch piece 7 is fixed inside the housing 1 and is rotatably connected to the rotating shaft 2, meaning that the fixed switch piece 7 does not rotate when the rotating shaft 2 rotates. The rotary switch piece 9 is fixedly connected to the rotating shaft 2, meaning that the rotary switch piece 9 rotates when the rotating shaft 2 rotates. In this embodiment, both the fixed switch piece 7 and the rotary switch piece 9 are provided with air outlets. By changing their relative positions, the air outlets on both the fixed switch piece 7 and the rotary switch piece 9 are partially blocked, and the blocked air outlets on both form regulating openings for the flow of ammonia.

[0033] Furthermore, in this embodiment, an elastic element is connected between the rotating shaft 2 and the housing 1. The elastic element is a rope structure with a rebound force, one end of which is fixed to the rotating shaft 2. As the rotating shaft 2 rotates, the elastic element gradually winds onto the rotating shaft 2 and is stretched. When the torsional force generated by the impeller 10 is balanced with the tension of the elastic element, the rotating shaft 2 stops rotating. At this time, the adjustment opening formed by the rotating switch piece 9 and the fixed switch piece 7 is used to allow the ammonia gas flow. For example, the elastic element is a spiral spring, which is a type of spring made by winding a thin spring material into a planar helix. One end is fixed, and after a torque is applied to the other end, the material is subjected to a bending moment, producing a bending elastic deformation, thus the spring torsions in its own plane. The magnitude of its deformation angle is proportional to the torque. It has relatively low stiffness and generally works under static load. In addition, the elastic element in this embodiment can also be Figure 1 The diagram shows a spring 3 and a metal wire 4. The two ends of the spring 3 are connected to the inner wall of the housing 1 and the metal wire 4, respectively. The metal wire 4 is mounted on the rotating shaft 2, and when the rotating shaft 2 rotates, the metal wire 4 winds around the rotating shaft 2 and stretches the spring 3. Therefore, in this application, the fluctuation of the flue gas flow rate drives the rotating shaft 2 to rotate, and the opening of the adjustment orifice is changed by the rotation angle of the rotating shaft 2. The opening of the adjustment orifice is positively correlated with the rotational displacement of the impeller 10, thus achieving the adjustment of the ammonia injection amount based on the fluctuation of the flue gas flow rate, so as to achieve the purpose of timely matching the ammonia injection amount with the flue gas flow rate.

[0034] In some embodiments, the fixed switch piece 7 is fixed inside the housing 1, and a bearing is connected between the middle part and the rotating shaft 2. The fixed switch piece 7 includes a first baffle, which is half of the area of ​​the fixed switch piece 7; the air outlet is the other half of the area of ​​the fixed switch piece 7.

[0035] The fixed switch piece 7 is fixed inside the housing 1, and the rotating shaft 2 passes through the middle of the fixed switch piece 7. A second bearing 8 is provided between the two, meaning that the fixed switch piece 7 does not rotate when the rotating shaft 2 rotates. The fixed switch piece 7 includes a first baffle, which can be understood as follows: Figure 2 The fixed switch piece 7 shown is a circular structure with a diameter adapted to the inner diameter of the housing 1; the first baffle is a semi-circular structure, and the other half of the fixed switch piece 7 is a semi-circular air outlet. The first baffle is half the area of ​​the fixed switch piece 7; the air outlet is the other half of the area of ​​the fixed switch piece 7. In addition, in some embodiments, the fixed switch piece 7 includes a first baffle and multiple air outlets opened on the first baffle; wherein the first baffle is half the area of ​​the fixed switch piece 7; the air outlet is the other half of the area of ​​the fixed switch piece 7. Therefore, this application has multiple implementation methods, which will not be listed one by one.

[0036] Similarly, in some embodiments, the rotary switch piece 9 is fixedly connected to the rotary shaft 2, and includes a second baffle, which is half the area of ​​the rotary switch piece 9; the air outlet is the other half of the area of ​​the fixed switch piece 7.

[0037] The rotary switch piece 9 is disposed within the housing 1, and the rotating shaft 2 passes through the middle of the rotary switch piece 9. A bearing is provided between the two, meaning that the rotary switch piece 9 rotates when the rotating shaft 2 rotates. The rotary switch piece 9 includes a second baffle, which can be understood as a circular piece structure with a diameter adapted to the inner diameter of the housing 1. The second baffle is a semi-circular structure, and the other half of the rotary switch piece 9 is a semi-circular air outlet. The second baffle is half the area of ​​the rotary switch piece 9, and the air outlet is the other half of the area of ​​the rotary switch piece 9. In some embodiments, the rotary switch piece 9 includes a second baffle and multiple air outlets formed on the second baffle; the second baffle is half the area of ​​the rotary switch piece 9, and the air outlet is the other half of the area of ​​the rotary switch piece 9. Therefore, this application has multiple implementations, which will not be listed one by one.

[0038] However, it should be noted that the opening degree of the adjustment opening is positively correlated with the rotational displacement of the impeller 10. That is, the greater the flue gas flow rate, the greater the rotational displacement of the impeller 10, the greater the rotation angle of the shaft, and the larger the area of ​​the adjustment opening formed by the fixed switch plate 7 and the rotary switch plate 9. This application has multiple implementation methods. For example, the fixed switch plate 7 and the rotary switch plate 9 have the same structure and diameter. The second baffle and the first baffle are semi-circular structures. In the initial state, the impeller 10 does not rotate, and the area of ​​the adjustment opening formed by the second baffle and the first baffle is zero. After the impeller 10 rotates, the rotating shaft 2 rotates, causing the second baffle and the first baffle to partially overlap. The spring 3 cannot be wound on the rotating shaft 2, which limits the second baffle and the first baffle to only partially overlap and then completely overlap in the same clockwise direction. That is, the maximum rotation angle of the second baffle is 180°, reaching the point where the second baffle and the first baffle completely overlap. At this time, the opening degree of the adjustment opening is the area of ​​the second baffle.

[0039] According to a second aspect of this application, a method for real-time automatic adjustment of flue gas flow rate is proposed, utilizing the ammonia nozzle in any of the above embodiments, comprising:

[0040] Under stable operating conditions: Ammonia gas flows into the housing 1 and is sprayed onto the impeller 10 through the outlet, causing the impeller 10 to rotate; when the impeller 10 rotates, the rotating shaft 2 rotates and the elastic element is wound and stretched until the torsional force generated by the impeller 10 is balanced with the tension of the elastic element; the rotating shaft 2 stops rotating; the ammonia gas flows through the adjustment opening formed by the rotary switch plate 9 and the fixed switch plate 7 and is sprayed out from the outlet;

[0041] When the operating conditions fluctuate, the change in the rotational displacement of the impeller 10 changes the rotation angle of the rotating shaft 2. The opening of the adjustment opening is adjusted according to the rotation angle of the rotating shaft 2, and the opening of the adjustment opening is positively correlated with the rotational displacement of the impeller 10.

[0042] Specifically, flue gas flows outside the housing 1, and ammonia flows inside the housing 1. Under stable operating conditions, when the flue gas encounters the impeller 10, the impeller 10 rotates, causing the rotating shaft 2 to rotate synchronously. The metal wire 4 connected to the rotating shaft 2 is wound around and simultaneously stretches the spring 3. When the torsional force generated by the impeller 10 is balanced with the tension of the spring 3, the rotating shaft 2 stops rotating. The fixed switch plate 7 and the rotary switch plate 9 form an adjustment opening through which the ammonia gas flows and is ejected from the outlet. By controlling the pressure of the ammonia gas in the ammonia nozzle, the amount of ammonia injected can be matched with the amount of ammonia required by the outside.

[0043] When operating conditions fluctuate, such as when the flue gas velocity increases, the rotational displacement of the impeller 10 increases, which in turn increases the rotation angle of the rotating shaft 2, thereby increasing the opening of the regulating orifice and increasing the ammonia injection rate. Conversely, the ammonia injection rate decreases accordingly. Whether under stable or fluctuating operating conditions, the tension of the spring 3 always remains in balance with the torsional force generated by the impeller 10, preventing the impeller 10 from rotating indefinitely.

[0044] It should be noted that in the description of this application, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0045] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the function involved, as will be understood by those skilled in the art to which embodiments of this application pertain.

[0046] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in at least one embodiment or example.

[0047] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A ammonia nozzle based on instantaneous automatic adjustment of flue gas flow rate characterized by, The shell comprises The shell is open at both ends and has an impeller arranged opposite to the outlet, ammonia gas flows into the shell and is sprayed through the outlet, the outlet of the shell is a converging horn, and the outlet corresponds to the middle part of the impeller, and the radius is smaller than the length of the blade of the impeller; the flue gas is sprayed on the impeller through the periphery of the shell; and The adjusting shaft comprises a rotating shaft, an elastic member and an adjusting opening; one end of the rotating shaft extends into the shell, and the other end is connected with the impeller; the elastic member is fixed in the shell and connected with the rotating shaft; the elastic member comprises a spring member and a wire; the two ends of the spring member are respectively connected with the inner wall of the shell and the wire, and the wire is arranged on the rotating shaft and wound on the rotating shaft when the rotating shaft rotates, thereby stretching the spring member; The fixed switch plate and the rotating switch plate connected with the rotating shaft in the shell are provided with air outlets; the fixed switch plate is fixed in the shell, a bearing is connected between the middle part of the fixed switch plate and the rotating shaft, and the fixed switch plate comprises a first baffle, and the first baffle is half of the area of the fixed switch plate; the air outlet of the fixed switch plate is the other half of the area of the fixed switch plate; The rotating switch plate is fixedly connected with the rotating shaft, and comprises a second baffle, and the second baffle is half of the area of the rotating switch plate; the air outlet of the rotating switch plate is the other half of the area of the rotating switch plate; the rotating switch plate partially blocks the air outlet when the rotating switch plate rotates with the rotating shaft; the remaining air outlet forms the adjusting opening through which the ammonia gas flows; the opening degree of the adjusting opening is positively correlated with the rotational displacement amount of the impeller. The fixed switch plate is a circular plate structure with a diameter matched with the inner diameter of the shell; and the first baffle is a semicircular structure.

2. The ammonia nozzle of claim 1, wherein, The rotating switch plate is a circular plate structure with a diameter matched with the inner diameter of the shell; and the second baffle is a semicircular structure.

3. The ammonia nozzle of claim 1, wherein, The fixed switch plate and the rotating switch plate have the same structure and diameter.

4. The ammonia nozzle according to any one of claims 1 to 3, characterized in that The rotating shaft is arranged in the shell through a support, and the support and the rotating shaft are connected through a bearing; the extension direction of the rotating shaft coincides with the central axis direction of the shell.

5. The ammonia nozzle of claim 4, wherein, The ammonia gas nozzle comprises the ammonia gas nozzle according to any one of claims 1-5, and further comprises 6. A method for instantaneously and automatically adjusting the flow rate of flue gas, characterized in that, Under stable working conditions, the flue gas is sprayed on the impeller and drives the impeller to rotate; when the impeller rotates, the rotating shaft rotates to stretch the elastic member until the torsional force generated by the impeller and the tension of the elastic member are balanced; the rotating shaft stops rotating; the ammonia gas flows through the adjusting opening formed by the rotating switch plate and the fixed switch plate and is sprayed out of the outlet; When the working conditions fluctuate, the rotational displacement amount of the impeller changes the rotation angle of the rotating shaft, and the opening degree of the adjusting opening is adjusted according to the rotation angle of the rotating shaft, wherein the opening degree of the adjusting opening is positively correlated with the rotational displacement amount of the impeller. ​

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