Flue Gas Ash Filtering Device and SCR Denitration System

Abstract

The present invention relates to a flue gas ash filtering device, which comprises an ash blocking grille and an ash hopper arranged below the ash blocking grille. The ash blocking grille comprises a plurality of ash blocking pipes which extend in the up and down direction. A hollow pipe cavity is formed inside the ash blocking pipes. The bottom of the ash blocking pipes forms an ash discharging port communicated with the pipe cavity. A plurality of holes are formed in the windward surface of the ash blocking pipes, and the holes are communicated with the pipe cavity. The SCR denitration system comprises an inlet flue, an SCR denitration reactor, an outlet flue and the flue gas ash filtering device. The ash blocking grille is arranged in the inlet flue, and the ash hopper is communicated with the outlet flue. The present invention can effectively remove large particulate ash in the flue gas, reduce the abrasion and blockage of the SCR denitration ammonia injection grille and the catalyst, improve the denitration performance and extend the service life; the ash accumulated in the ash hopper at the inlet flue falls to the outlet flue by gravity, without the need of high-pressure gas transportation, without increasing the electric load, without increasing the material energy consumption, and reducing the transformation and operation costs.

Description

Technical Field

[0001] The present invention relates to the technical field of SCR denitration, and particularly to a flue dust filtering device and an SCR denitration system. Background Art

[0002] The SCR denitration technology is the main technology for power plant boilers to achieve ultra-low emission standards of nitrogen oxides. At present, most SCR denitration reactors are arranged between the economizer and the air preheater of the boiler, and the denitration is prone to operate in a high-dust flue gas environment. The flue gas velocity at the inlet of the denitration flue is high. If the ash content in the flue gas is large, the flue gas carrying fly ash will scour the ammonia injection grid of the denitration for a long time, which may cause local wear of the ammonia injection grid and affect the uniformity of ammonia injection. The denitration catalyst is scoured by the flue gas with a high ash concentration for a long time, and surface interface wear will also occur, and even module collapse, resulting in reduced denitration performance and shortened service life. Therefore, reducing the fly ash content entering the denitration reactor is one of the necessary measures to ensure the long-term safe operation of the denitration device of power plant boilers.

[0003] At present, the main method to reduce the fly ash content entering the denitration reactor is to install an ash collection hopper at the bottom of the inlet flue of the denitration to collect some large particle ash and sedimented ash in the flue. However, the ash removal efficiency is low, and most of the ash is still carried by the flue gas into the reactor, and an additional pneumatic ash conveying system needs to be installed, increasing the transformation and operation costs. Therefore, in the prior art, a physical structure is mostly used to intercept or break large particle ash in the flue gas before the flue gas enters the denitration reactor, so as to achieve the purpose of pre-removing ash.

[0004] Referring to the patent with the publication number CN202962157U, it discloses an SCR denitration static pre-ash removal device. This device pre-adsorbs ash particles that are easy to block the pores by setting a honeycomb grid in the horizontal flue at the SCR denitration inlet. However, this device can only adsorb a small amount of sticky dust, and the blocked honeycomb grid needs to be cleaned regularly, increasing the maintenance cost.

[0005] Referring to the patent with the publication number CN209049144U, it discloses a pre-treatment ash crushing net for an SCR denitration device. This device is arranged in the horizontal flue at the economizer outlet and the denitration inlet flue, and intercepts and breaks large particle ash through a dust interception net with a pore diameter less than 7 mm. However, the pore diameter of the dust interception net of this device is small, the flue gas resistance is large, and it is easy to be damaged under the scouring action of high-velocity ash, and needs to be replaced regularly.

[0006] Under this background, it is very promising to develop an economical and efficient ash removal device. Summary of the Invention

[0007] An object of the present invention is to provide a flue dust filtering device.

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] A flue gas ash filtering device, which includes an ash blocking grid and an ash hopper arranged below the ash blocking grid. The ash blocking grid includes multiple ash blocking pipes. The ash blocking pipes extend in the up and down direction. A hollow pipe cavity is formed inside the ash blocking pipes. A ash discharging port communicating with the pipe cavity is formed at the bottom of the ash blocking pipes. Multiple holes are opened on the windward surface of the ash blocking pipes, and the holes communicate with the pipe cavity.

[0010] Preferably, at least two rows of the ash blocking pipes are arranged along the flue gas flow direction, and multiple ash blocking pipes are arranged in each row. The adjacent two rows of ash blocking pipes are staggered, that is, one ash blocking pipe in the rear row is located behind the two ash blocking pipes in the front row.

[0011] Preferably, multiple holes are opened along the extending direction of the ash blocking pipes, and the multiple holes are evenly distributed on the windward surface of the ash blocking pipes.

[0012] Preferably, the device further includes a ash falling pipe and an air lock arranged on the ash falling pipe. The ash falling pipe communicates with the ash hopper.

[0013] Further preferably, the air lock includes an ash accumulating pipe assembly. The ash accumulating pipe assembly includes a pipe body with an inlet communicating with the ash hopper outlet, and a flap arranged at the outlet of the pipe body. One end of the flap is rotatably connected to one side of the pipe body outlet, and a counterweight for controlling the opening and closing of the pipe body outlet by the flap is arranged at the turning point of the flap.

[0014] Further preferably, multiple groups of the ash accumulating pipe assemblies are arranged, and the multiple groups of ash accumulating pipe assemblies are arranged up and down.

[0015] Further preferably, the outlet end face of the pipe body is an inclined plane.

[0016] Another object of the present invention is to provide an SCR denitration system. The SCR denitration system is provided with a flue gas ash filtering device to effectively filter large particle ash before the flue gas enters the SCR denitration reactor, so as to reduce the wear and blockage of the SCR denitration ammonia injection grid and catalyst.

[0017] To achieve the above object, the technical solution adopted by the present invention is:

[0018] An SCR denitration system, which includes an inlet flue, an SCR denitration reactor with an inlet communicating with the inlet flue, and an outlet flue communicating with the outlet of the SCR denitration reactor. The system further includes the flue gas ash filtering device. The ash blocking grid is arranged in the inlet flue, and the outlet of the ash hopper communicates with the outlet flue.

[0019] Preferably, the flue gas ash filtering device is arranged in the horizontal section of the inlet flue, and the outlet of the ash hopper is communicated with the horizontal section of the outlet flue.

[0020] More preferably, the horizontal section of the inlet flue is located above the horizontal section of the outlet flue.

[0021] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0022] 1. After adding the flue gas ash filtering device, the flue resistance increases slightly, but it can effectively remove large particle ash in the flue gas, thereby reducing the wear and blockage of the SCR denitration ammonia injection grid and catalyst, improving the denitration performance and extending the service life;

[0023] 2. The ash collected by the ash hopper at the inlet flue falls to the outlet flue by gravity, without the need for high-pressure gas transportation, without increasing the electrical load, without increasing the material energy consumption, and reducing the transformation and operation costs. Description of the Drawings

[0024] Attached Figure 1 is a three-dimensional schematic diagram of the SCR denitration system in this embodiment;

[0025] Attached Figure 2 is a front view schematic diagram of the SCR denitration system in this embodiment;

[0026] Attached Figure 3 is a side view schematic diagram of the flue gas ash filtering device in this embodiment;

[0027] Attached Figure 4 is a three-dimensional schematic diagram of the ash blocking grid in this embodiment;

[0028] Attached Figure 5 is a side view schematic diagram of the ash blocking grid in this embodiment;

[0029] Attached Figure 6 is a front view schematic diagram of the air lock in this embodiment.

[0030] In the above drawings:

[0031] 10. Inlet flue; 11. SCR denitration reactor; 12. Outlet flue; 2. Ash blocking grid; 20. Ash blocking pipe; 200. Hole; 3. Ash hopper; 4. Ash dropping pipe; 5. Air lock; 50. Pipe body; 51, 51'. Flap; 52. Counterweight. Detailed Embodiments

[0032] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0033] 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 accompanying drawings. It 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 thus cannot be construed as a limitation of the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0034] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. 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.

[0035] As Figure 1 、 2 shown, a SCR denitration system includes an inlet flue 10, a SCR denitration reactor 11 whose inlet is connected to the inlet flue 10, and an outlet flue 12 connected to the outlet of the SCR denitration reactor 11. The system further includes a flue ash filtering device.

[0036] As Figure 3 shown: The flue ash filtering device includes an ash interception grid 2 and an ash hopper 3 arranged below the ash interception grid 2. The ash interception grid 2 is arranged in the inlet flue 10, and the outlet of the ash hopper 3 is connected to the outlet flue 12. In this embodiment: The ash interception grid 2 includes a plurality of ash interception pipes 20. The ash interception pipes 20 extend in the up and down direction. A hollow pipe cavity is formed inside the ash interception pipes 20. The bottom of the ash interception pipes 20 forms a ash discharge port connected to the pipe cavity. A plurality of holes 200 connected to the pipe cavity are opened on the windward surface of the ash interception pipes 20. A plurality of holes 200 are opened along its extending direction, and the plurality of holes 200 are evenly distributed on the windward surface of the ash interception pipes 20.

[0037] The ash blocking pipes 20 are arranged in at least two rows along the flue gas flow direction, with multiple ash blocking pipes 20 in each row, and adjacent two rows of ash blocking pipes 20 are staggeredly distributed. That is to say, one ash blocking pipe 20 in the rear row is located behind the space between two ash blocking pipes 20 in the front row. Taking two rows as an example in the figure, as Figure 4 , 5 shown.

[0038] The outlet of the ash hopper 3 is connected to the outlet flue 12 through the ash dropping pipe 4, and an air lock 5 is arranged on the ash dropping pipe 4 to prevent flue gas from directly flowing into the outlet flue 12 from the ash dropping pipe 4. The air lock 5 adopts a flap air lock. In this embodiment: The air lock 5 includes an ash accumulating pipe assembly. The ash accumulating pipe assembly includes a pipe body 50 with an inlet communicating with the outlet of the ash hopper 3, a flap 51 arranged at the outlet of the pipe body 50, and the outlet end face of the pipe body 50 is an inclined plane; one end of the flap 51 is rotatably connected to one side of the outlet of the pipe body 50, and a weight 52 for controlling the opening and closing of the outlet of the pipe body by the flap 51, such as a heavy hammer, etc., is arranged at the rotation point of the flap 51. Multiple groups of ash accumulating pipe assemblies are arranged, and multiple groups of ash accumulating pipe assemblies are arranged up and down. Taking two groups as an example in the figure, as Figure 6 shown.

[0039] The flue gas ash filtering device is arranged at the end of the horizontal section of the inlet flue 10. The outlet of the ash hopper 3 is connected to the horizontal section of the outlet flue 12 through the ash dropping pipe 5, and the horizontal section of the inlet flue 10 is located above the horizontal section of the outlet flue 12. The length of the ash dropping pipe 5 is the shortest, and the ash discharge is the smoothest.

[0040] The working process of this embodiment is specifically described as follows:

[0041] Flue gas enters from the inlet flue 10 and blows towards the ash blocking grid 2. Part of the flue gas flows around the ash blocking grid 2 to the downstream, and part of the flue gas enters the cavity of the ash blocking pipe 20 through the holes 200 of the ash blocking pipe 20, collides with the inner wall and then turns back. After the large particle ash collides with the wall surface and loses kinetic energy, it falls to the ash hopper 3 along the cavity of the ash blocking pipe 20 through its ash discharge port under the action of gravity;

[0042] The flap 51 of the air lock 5 is controlled by the weight 52 through the rotation point and is in a normally closed state. Ash continuously deposits on the upper flap 51. When the moment on the rotation point caused by it is greater than the moment on the rotation point caused by the weight 52, the upper flap 51 opens, and the ash gradually falls onto the lower flap 51'. At this time, the lower flap 51' still remains closed; when the moment on the rotation point caused by the accumulated ash is less than the moment on the rotation point caused by the weight 52, the upper flap 51 resets, and the lower flap 51' opens under the action of the gravity of the ash. The accumulated ash enters the outlet flue 12 through the ash dropping pipe 4, thereby realizing periodic intermittent ash discharge and reducing the abrasion and blockage of fly ash to the denitration ammonia injection grid and catalyst.

[0043] It is intended to apply this device to the SCR denitration system of a 600MW unit in a coal-fired power plant. The designed flue gas flow rate is about 1892970 Nm3 / h; the cross-sectional width of the horizontal flue at the SCR denitration inlet is 12m, the height is 4m, and 4 ash hoppers are arranged side by side, each ash hopper is 2.5m high; the ash intercepting grilles are arranged in a staggered pattern, with 29 in the front row and 30 in the back row. The ash intercepting pipes have a diameter of DN100 and a height of 4m. Each ash intercepting pipe has 40 holes with a diameter of 70mm on the windward side. After simulation calculation, the flue gas resistance increases by about 140Pa after installing this device.

[0044] The above embodiments are only used to illustrate the technical concept and characteristics of the present invention. The purpose is to enable those familiar with this technology 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. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A flue gas ash filtering device, characterized in that: the device includes an ash interception grille and an ash hopper arranged below the ash interception grille. The ash interception grille includes multiple ash interception pipes. The ash interception pipes extend in the up and down direction. A hollow pipe cavity is formed inside the ash interception pipes. A ash discharge port communicating with the pipe cavity is formed at the bottom of the ash interception pipes. Multiple holes are formed on the windward surface of the ash interception pipes, and the holes communicate with the pipe cavity.

2. The flue gas ash filtering device according to claim 1, characterized in that: at least two rows of the ash interception pipes are arranged along the flue gas flow direction, and multiple ash interception pipes are arranged in each row. The adjacent two rows of ash interception pipes are staggered.

3. The flue gas ash filtering device according to claim 1, characterized in that: multiple holes are formed along the extending direction of the ash interception pipes, and the multiple holes are evenly distributed on the windward surface of the ash interception pipes.

4. The flue gas ash filtering device according to claim 1, characterized in that: the device further includes a ash dropping pipe and a air lock arranged on the ash dropping pipe. The ash dropping pipe communicates with the ash hopper.

5. The flue gas ash filtering device according to claim 4, characterized in that: the air lock includes an ash accumulating pipe assembly. The ash accumulating pipe assembly includes a pipe body with an inlet communicating with the ash hopper outlet, and a flap arranged at the outlet of the pipe body. One end of the flap is rotatably connected to one side of the pipe body outlet, and a counterweight for controlling the opening and closing of the pipe body outlet by the flap is arranged at the turning point of the flap.

6. The flue gas ash filtering device according to claim 5, characterized in that: multiple groups of the ash accumulating pipe assemblies are arranged, and the multiple groups of ash accumulating pipe assemblies are arranged up and down.

7. The flue gas ash filtering device according to claim 5, characterized in that: the outlet end face of the pipe body is an inclined plane.

8. An SCR denitration system, which includes an inlet flue, an SCR denitration reactor with an inlet communicating with the inlet flue, and an outlet flue communicating with the outlet of the SCR denitration reactor, characterized in that: the system further includes the flue gas ash filtering device according to any one of claims 1 to 7. The ash interception grille is arranged in the inlet flue, and the outlet of the ash hopper communicates with the outlet flue.

9. The SCR denitration system according to claim 8, characterized in that: the flue gas ash filtering device is arranged in the horizontal section of the inlet flue, and the outlet of the ash hopper communicates with the horizontal section of the outlet flue.

10. The SCR denitration system according to claim 9, characterized in that: the horizontal section of the inlet flue is located above the horizontal section of the outlet flue.

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