A pre-dust removal device for the SCR reactor of a coal-fired unit

Abstract

The present invention relates to a pre-dust removal device for an SCR reactor of a coal-fired unit, which includes an economizer outlet flue, an SCR reaction component, and an ash hopper. The ash hopper is connected to the outlet of the economizer outlet flue and is located below the outlet of the economizer outlet flue. The SCR reaction component is connected to the economizer outlet flue through an SCR inlet flue. The device further includes a baffle assembly, which is arranged at the mouth of the ash hopper. The baffle assembly includes multiple baffles, and the baffles are rotatably arranged. The rotation axis of the baffles is arranged horizontally so that the baffles rotate in a direction approaching or departing from the inlet of the SCR inlet flue. In the present invention, a baffle assembly is arranged on the ash hopper at the outlet of the economizer flue. By rotating the baffle to change the angle between it and the horizontal plane, the flue resistance and ash interception efficiency can be controlled, and efficient interception and collection of fine ash and large particle ash can be achieved without significantly increasing the flue resistance, thereby effectively preventing the problems of catalyst ash accumulation blockage and wear.

Description

Technical Field

[0001] The present invention belongs to the technical field of SCR denitration in coal-fired power plants, and particularly relates to a pre-dust removal device for an SCR reactor of a coal-fired unit. Background Art

[0002] SCR: Selective Catalytic Reduction, abbreviated as SCR. The SCR denitration technology refers to the technology in which, within the range of 280 - 420 °C, a reducing agent (such as liquid ammonia, urea, ammonia water, etc.) reacts "selectively" with NO in the flue gas under the action of a catalyst x to produce pollution-free N 2 and H 2 O for NO x emission reduction.

[0003] With the increasingly strict NO x emission standards, NH 3 -method SCR flue gas denitration devices have been generally installed in coal-fired power plants in China. This device utilizes the redox reaction that occurs when NO x and ammonia gas pass through the catalyst to achieve the purpose of removing NO x from the flue gas. Among them, the catalyst is the most important component. When the flue gas carrying a large amount of fly ash enters the SCR reactor, it is easy to cause problems such as catalyst ash accumulation blockage and erosion wear, reducing the service life of the catalyst. Therefore, how to efficiently remove the fly ash entering the catalyst area is the key to improving the denitration efficiency of the catalyst and extending its life cycle.

[0004] Currently in China, for such problems, large particulate fly ash in the flue gas is mainly removed by arranging an interception net at the inlet of the denitration device. The interception net is in the form of a metal screen or a perforated plate, covering the entire flue cross-section. If the aperture of the metal screen or perforated plate is large, the interception effect on fly ash is not good; if the aperture is small, the resistance generated is large, and it is also extremely easy to have a blockage problem. In addition, the above research is basically aimed at large particulate fly ash, and there is relatively little interception of fine ash particles.. Summary of the Invention

[0005] The purpose of the present invention is to provide a pre-dust removal device for an SCR reactor of a coal-fired unit..

[0006] To achieve the above purpose, the technical solution adopted by the present invention is:

[0007] A pre-dust removal device for an SCR reactor of a coal-fired unit, comprising an economizer outlet flue, an SCR reaction component, and a hopper. The hopper is connected to the outlet of the economizer outlet flue and is located below the outlet of the economizer outlet flue. The SCR reaction component is connected to the economizer outlet flue through an SCR inlet flue, and the connection between the SCR inlet flue and the economizer outlet flue is located on one side of the economizer outlet flue and the hopper. The device further includes a baffle assembly. The baffle assembly is arranged at the mouth of the hopper. The baffle assembly includes multiple baffles. The baffles are rotatably arranged. The rotation axis of the baffles is arranged horizontally so that the baffles rotate in a direction close to or away from the inlet of the SCR inlet flue.

[0008] Preferably, the baffle includes a first baffle and a second baffle. The second baffle is the baffle closest to the inlet of the SCR inlet flue. There are multiple first baffles, which are sequentially distributed in a direction away from the second baffle.

[0009] Further preferably, the length of the first baffle is a, and a is 500 - 700 mm.

[0010] Further preferably, the distance between the rotation axes of two adjacent first baffles is 700 - 1000 mm.

[0011] Further preferably, the length of the second baffle is b, the height of the inlet of the SCR inlet flue is c, and b is one-eighth to one-fourth of c.

[0012] Further preferably, the second baffle has a limit state. When the second baffle is in this limit state, one end of the second baffle is connected to the bottom of the inlet of the SCR inlet flue.

[0013] Even more preferably, when the second baffle is in this limit state, the angle between the second baffle and the horizontal plane is 60°.

[0014] Preferably, the rotation angle of the baffle relative to the horizontal plane is 0 - 90°.

[0015] Further preferably, when the baffle rotates between greater than 0° and less than 90°, the distance from the upper end of the baffle to the inlet of the SCR inlet flue is greater than the distance from the lower end of the baffle to the inlet of the SCR inlet flue.

[0016] Preferably, the device further includes an ash baffle located in the flue of the economizer outlet, and the ash baffle is arranged above the connection of the SCR inlet flue and the economizer outlet flue, and extends in a direction away from the SCR inlet flue and close to the ash hopper.

[0017] More preferably, the angle between the ash baffle and the vertical plane is 40-75°.

[0018] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0019] The present invention sets a baffle assembly on the ash hopper at the outlet of the economizer flue, and controls the flue resistance and ash interception efficiency by rotating the baffle to change the angle between it and the horizontal plane, so as to achieve efficient interception and collection of fine ash and large particle ash without significantly increasing the flue resistance, thereby effectively preventing the problems of catalyst ash accumulation, blockage and wear. Description of the Drawings

[0020] Att Figure 1 is a schematic structural diagram of this embodiment;

[0021] Att Figure 2 is Att Figure 1 is an enlarged schematic diagram of part A in the attached figure.

[0022] In the above drawings: 1. economizer outlet flue; 2. SCR reaction component; 3. ash hopper; 4. ash baffle; 51. first baffle; 52. second baffle; 53. rotating shaft; 6. SCR inlet flue. Detailed Embodiments

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0025] In the description of the present invention, it should be noted that, unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be a direct connection or an indirect connection through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] As Figure 1 shown, a pre-dust removal device for an SCR reactor of a coal-fired unit includes an economizer outlet flue 1, an SCR reaction component 2, a hopper 3, a baffle assembly, and a dust retaining plate 4. The hopper 3 is communicated with the outlet of the economizer outlet flue 1 and is located below the outlet of the economizer outlet flue 1. The SCR reaction component 2 is communicated with the economizer outlet flue 1 through an SCR inlet flue 6, and the connection between the SCR inlet flue 6 and the economizer outlet flue 1 is located on one side of the economizer outlet flue 1 and the hopper 3. When the flue gas flows from the economizer to the SCR reaction component 2, it successively passes through the economizer outlet flue 1, the hopper 3, and the SCR inlet flue 6, and passes through the hopper 3 when the flow direction thereof bends. Fly ash and other impurities in the flue gas fall into the hopper 3.

[0027] The baffle assembly is arranged at the mouth of the hopper 3. The baffle assembly includes multiple baffles, and the baffles are rotatably arranged. The rotation axis 53 of the baffles is arranged horizontally so that the baffles rotate in a direction approaching or departing from the inlet of the SCR inlet flue 6. In this embodiment, the rotation axis 53 is arranged in the middle of the baffle and is parallel to the plane where the inlet of the SCR inlet flue 6 is located. The rotation angle between the baffle and the horizontal plane is 0 to 90°, and when the included angle between the baffle and the horizontal plane is greater than 0° and less than 90°, the distance from the upper end of the baffle to the inlet of the SCR inlet flue 6 is greater than the distance from the lower end of the baffle to the inlet of the SCR inlet flue 6. By controlling the rotation axis 53, the rotation angle of the baffle is controlled. When the unit operates at high load, the flue gas volume is large and the average flue gas velocity is high. Rotate the rotation axis 53 to reduce the angle between the baffle and the horizontal plane, and the resistance of the SCR denitration device can be reduced without significantly affecting the dust retaining efficiency; when the unit operates at low load, the flue gas volume is small and the average flue gas velocity is low. Rotate the rotation axis 53 to increase the angle between the baffle and the horizontal plane, and the dust retaining efficiency is improved without significantly increasing the flue resistance.

[0028] The baffle plate includes a first baffle plate 51 and a second baffle plate 52. The second baffle plate 52 is the baffle plate closest to the inlet of the SCR inlet flue 6. There are multiple first baffle plates 51, which are distributed in sequence in the direction away from the second baffle plate 52. The length of the first baffle plate 51 is a, and a is 500 - 700 mm. The distance between the rotating shafts 53 of two adjacent first baffle plates 51 is 700 - 1000 mm. The length of the second baffle plate 52 is b, the height of the inlet of the SCR inlet flue 6 is c, and b is one-eighth to one-fourth of c. The rotation angle range of the second baffle plate 52 is smaller than that of the first baffle plate 51, which is 0 - 60°, and the second baffle plate 52 has a limit state. When the second baffle plate 52 is in this limit state, the included angle between the second baffle plate 52 and the horizontal plane is 60°. One end of the second baffle plate 52 is connected to the bottom of the inlet of the SCR inlet flue 6, and at this time, the ash blocking effect is the best. After the unit has been operating for a period of time, a certain amount of ash will accumulate on the leeward side (i.e., the side facing the SCR inlet flue 6) of the second baffle plate 52. By adjusting the rotating shaft 53, the second baffle plate 52 can be rotated to the horizontal state, and the flue gas can flow through the bottom of the second baffle plate 52 to blow away the accumulated ash, thereby improving the ash accumulation condition at the bottom of the inlet of the SCR inlet flue 6.

[0029] The device further includes an ash blocking plate 4 located in the economizer outlet flue 1. The ash blocking plate 4 can adjust the flow direction of the flue gas when it flows out of the economizer outlet flue 1. The ash blocking plate 4 is arranged above the connection between the SCR inlet flue 6 and the economizer outlet flue 1 and extends in the direction away from the SCR inlet flue 6 and close to the ash hopper 3. The included angle between the ash blocking plate 4 and the vertical plane is 45 - 70°.

[0030] Table 1 shows the physical model test results of measuring the resistance and ash blocking effect of the device by using the physical model test method:

[0031] Table 1

[0032]

[0033] It can be seen from the table that the device of this embodiment realizes the efficient interception and collection of fine ash and large particle ash on the premise of not significantly increasing the flue resistance.

[0034] The optimal position, angle, length and other parameters of the specific arrangement of the first baffle plate 51, the second baffle plate 52 and the ash blocking plate 4 can be obtained by optimizing according to the actual environment of CFD numerical simulation.

[0035] The working principle of this embodiment is specifically described as follows:

[0036] When the flue gas carrying a large amount of fly ash enters the economizer outlet flue 1 ( Figure 1In the direction of the arrow shown, under the action of the ash baffle 4, most of the large-particle fly ash near the inlet of the SCR inlet flue 6 is introduced into the ash hopper 3, and the second baffle 52 intercepts and collects the large-particle ash with low density that has not fallen into the ash hopper 3 and the large-particle ash that escapes from the ash hopper 3. The fine ash and large-particle ash far from the inlet of the SCR inlet flue 6 enter the middle and lower part of the ash hopper 3 under the action of the first baffle 51 above the ash hopper 3 and are captured by the ash hopper 3. By controlling the rotating shaft 53, the included angles between the first baffle 51 and the second baffle 52 above the ash hopper 3 and the horizontal plane are adjusted, so as to control the flue resistance and the ash interception efficiency.

[0037] The above embodiments are only for illustrating the technical concept and characteristics of the present invention, and the purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and it cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A pre-dust removal device for an SCR reactor of a coal-fired unit, comprising an economizer outlet flue, an SCR reaction component, and a hopper. The hopper is communicated with the outlet of the economizer outlet flue and is located below the outlet of the economizer outlet flue. The SCR reaction component is communicated with the economizer outlet flue through an SCR inlet flue, and the connection between the SCR inlet flue and the economizer outlet flue is located on one side of the economizer outlet flue and the hopper. Characterized in that: The device further includes a baffle assembly and a dust blocking plate located in the economizer outlet flue. The baffle assembly includes a plurality of baffles arranged horizontally at the hopper opening. The baffles are rotatably arranged, and the rotation axes of the baffles are arranged horizontally so that the baffles rotate in a direction approaching or departing from the inlet of the SCR inlet flue. The baffles include a first baffle and a second baffle. The second baffle is the baffle closest to the inlet of the SCR inlet flue. There are a plurality of first baffles and they are arranged in sequence in a direction away from the second baffle. The length of the first baffle is a, where a is 500 - 700 mm. The distance between the rotation axes of two adjacent first baffles is 700 - 1000 mm. The length of the second baffle is b, and the height of the inlet of the SCR inlet flue is c. b is one-eighth to one-fourth of c. The dust blocking plate is arranged above the connection between the SCR inlet flue and the economizer outlet flue and extends in a direction away from the SCR inlet flue and towards the hopper.

2. The pre-dust removal device for an SCR reactor of a coal-fired unit according to claim 1, Characterized in that: The second baffle has a limit state. When the second baffle is in this limit state, one end of the second baffle is connected to the bottom of the inlet of the SCR inlet flue.

3. The pre-dust removal device for an SCR reactor of a coal-fired unit according to claim 1, Characterized in that: The rotation angle of the baffle relative to the horizontal plane is 0 - 90°.

4. The pre-dust removal device for an SCR reactor of a coal-fired unit according to claim 3, Characterized in that: When the baffle rotates between greater than 0° and less than 90°, the distance from the upper end of the baffle to the inlet of the SCR inlet flue is greater than the distance from the lower end of the baffle to the inlet of the SCR inlet flue.

5. The pre-dust removal device for an SCR reactor of a coal-fired unit according to claim 1, Characterized in that: The included angle between the dust blocking plate and the vertical plane is 40 - 75°.

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