Sweeping system for ammonia injection grid of SCR (Selective Catalytic Reduction) denitration device

Abstract

The utility model discloses an SCR (Selective Catalytic Reduction) denitration device ammonia injection grid purging system, an SCR denitration device comprises a flue, an ammonia injection grid is arranged at an inlet of the flue, and the purging system comprises a compressed air source, a first connecting pipe and a gas channeling prevention unit; wherein an air inlet of the first connecting pipe is connected with an air outlet of the compressed air source, and an air outlet of the first connecting pipe is communicated with an air inlet of the ammonia spraying grid; the gas channeling prevention unit comprises two flanges connected to the first connecting pipe and an 8-shaped blind plate, the two flanges are connected to the first connecting pipe, the 8-shaped blind plate is located between the two flanges, the 8-shaped blind plate is rotationally connected with one flange through a rotating shaft, and the two flanges are connected through a bolt; the ammonia injection grille can be purged by compressed air through the compressed air source during operation of the boiler or after the boiler is shut down, in addition, the 8-shaped blind plate is arranged on the first connecting pipe, and ammonia gas and compressed air media can be prevented from channeling through the 8-shaped blind plate, so that the safety problem caused by overflow of the ammonia gas is avoided.

Description

Technical Field

[0001] The utility model belongs to the technical field of air purification devices, and in particular relates to an ammonia spraying grid purge system for an SCR denitration device. Background Art

[0002] The SCR denitrification device fully mixes ammonia with air from the dilution fan in an ammonia / air mixer. The mixed gas enters the ammonia injection grid at the flue inlet of the SCR denitrification device, and after being fully mixed with the flue gas, it enters the SCR denitrification catalyst. Under the action of the catalyst, ammonia and nitrogen oxides in the flue gas react to produce water and nitrogen, thereby achieving an environmentally friendly process.

[0003] The existing dilution fan's outlet flow rate cannot be adjusted. The overall flow rate and pressure of the air and ammonia flowing from the dilution fan into the ammonia injection grid are low. Furthermore, the fly ash moisture in the flue gas increases due to the mixing of other substances in the boiler. This causes the nozzles of the ammonia injection grid to easily become clogged due to ash accumulation. Clogged nozzles require cleaning, and the current cleaning method involves personnel entering the flue to manually knock and clear the ammonia injection grid after each boiler shutdown.

[0004] Ammonia is a toxic gas that is harmful to the human respiratory system and eyes. Exposure to high concentrations of ammonia may cause breathing difficulties, eye and respiratory tract irritation, and even poisoning. The ammonia injection grid is a relatively closed space, and there may be problems of narrow space and poor ventilation when entering. In this environment, the ammonia concentration may accumulate, increasing the risk of poisoning. In addition, there is a risk of people falling when manually entering the flue for cleaning. Utility Model Content

[0005] The purpose of the utility model is to provide an ammonia spraying grid purge system for an SCR denitration device, which solves the above problems.

[0006] The technical solution adopted by the present invention is an ammonia spraying grid purge system for an SCR denitrification device, wherein the SCR denitrification device includes a flue, an ammonia spraying grid is provided at the entrance of the flue, and the purge system includes:

[0007] a compressed air source, the air outlet of which is connected to the air inlet of the first connecting pipe, and the air outlet of the first connecting pipe is connected to the ammonia injection grid;

[0008] The gas mutual crosstalk prevention unit includes two flanges and an 8-shaped blind plate connected to a first connecting pipe. The two flanges are connected to the first connecting pipe, and the 8-shaped blind plate is located between the two flanges. At the same time, the 8-shaped blind plate is rotatably connected to one of the flanges through a rotating shaft, and the two flanges are connected by bolts.

[0009] The air outlet of the compressed air source is also connected to a sonic soot blower, and the air outlet of the sonic soot blower is connected to the air inlet of the first connecting pipe.

[0010] A first ball valve is also provided on the first connecting pipe, and the first ball valve is located upstream of the 8-shaped blind plate.

[0011] Ten ammonia injection grids are provided at the entrance of the flue, and the first connecting pipe is connected to the ten groups of ammonia injection grids one by one through ten second connecting pipes.

[0012] Each second connecting pipe is provided with a second ball valve.

[0013] An ammonia injection main pipe is also provided on the outside of the flue, and a third ball valve is provided between the ammonia injection main pipe and each ammonia injection grid.

[0014] The beneficial effects of the utility model are:

[0015] The utility model discloses an ammonia spray grid purging system for an SCR denitration device, the purging system comprising: a compressed air source, a first connecting pipe and an 8-shaped blind plate; the air inlet of the first connecting pipe is connected to the air outlet of the compressed air source, the air outlet of the first connecting pipe is communicated with the air inlet of the ammonia spray grid, and the 8-shaped blind plate is arranged on the first connecting pipe; the utility model can use compressed air to purge the ammonia spray grid during boiler operation or after shutdown by increasing the compressed air source, and the 8-shaped blind plate is further arranged on the first connecting pipe, and the 8-shaped blind plate can prevent ammonia and compressed air from mutual crosstalk by the 8-shaped blind plate, thereby avoiding safety problems caused by ammonia overflow, and in addition, this cleaning by the compressed air source can avoid manual knocking and dredging, thereby eliminating the risk of falling of the staff working in this project. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a single-line diagram of the ammonia grid and compressed air pipeline of the ammonia grid purge system of the SCR denitrification device;

[0017] Figure 2 The utility model is an overall schematic diagram of an ammonia injection grid purge system of an SCR denitration device.

[0018] In the figure, 1. compressed air source, 2. flue, 3. first connecting pipe, 4. first ball valve, 5. 8-shaped blind plate, 6. second connecting pipe, 7. second ball valve, 8. third ball valve, 9. ammonia injection grid. DETAILED DESCRIPTION

[0019] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention and are not intended to limit the protection scheme of the present invention.

[0020] The SCR denitrification device fully mixes ammonia with air from the dilution fan in an ammonia / air mixer. The mixed gas enters the ammonia injection grid at the flue inlet of the SCR denitrification device, and after being fully mixed with the flue gas, it enters the SCR denitrification catalyst. Under the action of the catalyst, ammonia and nitrogen oxides in the flue gas react to produce water and nitrogen, thereby achieving an environmentally friendly process.

[0021] The existing dilution fan's outlet flow rate cannot be adjusted. The overall flow rate and pressure of the air and ammonia flowing from the dilution fan into the ammonia injection grid are low. Furthermore, the fly ash moisture in the flue gas increases due to the mixing of other substances in the boiler. This causes the nozzles of the ammonia injection grid to easily become clogged due to ash accumulation. Clogged nozzles require cleaning, and the current cleaning method involves personnel entering the flue to manually knock and clear the ammonia injection grid after each boiler shutdown.

[0022] Ammonia is a toxic gas that is harmful to the human respiratory system and eyes. Exposure to high concentrations of ammonia may cause breathing difficulties, eye and respiratory tract irritation, and even poisoning. The ammonia injection grid is a relatively closed space, and there may be problems of narrow space and poor ventilation when entering. In this environment, the ammonia concentration may accumulate, increasing the risk of poisoning. In addition, there is a risk of people falling when manually entering the flue for cleaning.

[0023] The utility model provides an SCR denitration device ammonia spraying grid purge system, such as Figure 1-2 As shown, the SCR denitrification device includes a flue 2, and an ammonia injection grid 9 is provided at the entrance of the flue. The purge system includes: a compressed air source 1, a first connecting pipe 3 and a gas crosstalk prevention unit; wherein the air inlet of the first connecting pipe 3 is connected to the air outlet of the compressed air source 1, and the air outlet of the first connecting pipe 3 is connected to the air inlet of the ammonia injection grid 9; wherein the compressed air source 1 can also use a nitrogen source, and the gas crosstalk prevention unit includes two flanges and an 8-shaped blind plate 5 connected to the first connecting pipe 3, the two flanges are connected to the first connecting pipe 3, the 8-shaped blind plate 5 is located between the two flanges, and the 8-shaped blind plate 5 is rotatably connected to one of the flanges through a rotating shaft, and the two flanges are connected by bolts. The 8-shaped blind plate is a pipeline component, mainly for easy maintenance. Half of the 8-shaped blind plate is an iron ring, which is often used in pipelines where the process needs to be changed.

[0024] In order to improve the cleaning effect of the nozzles on the ammonia injection grid, the air outlet of the compressed air source 1 disclosed in this embodiment is also connected to a sonic soot blower, and the air outlet of the sonic soot blower is connected to the air inlet of the first connecting pipe 3. The sonic soot blower technology converts compressed air (or steam) into high-power sound waves or infrasound waves (a pressure wave that propagates in a spatial medium (gas) in the form of a density wave) and sends it into the pipeline. When the accumulated soot is repeatedly pulled and compressed by the density waves that alternate at a certain frequency, it becomes loose and falls off due to fatigue and is carried away with the flue gas flow; therefore, the sonic soot blower can improve the cleaning effect of the nozzles on the ammonia injection grid.

[0025] Furthermore, a first ball valve 4 is provided on the first connecting pipe 3. The function of the first ball valve is to control the compressed air or nitrogen purge of the ammonia spray grid. Under normal circumstances, the first ball valve 4 is in a closed state. When compressed air is purged, the first ball valve 4 is opened.

[0026] The 8-shaped blind plate 5 is located downstream of the first ball valve 4. The 8-shaped blind plate is installed between the two flanges on the first connecting pipe 3. The purpose of setting the 8-shaped blind plate is to prevent ammonia and compressed air from interflowing. Under normal circumstances, the operating state of the 8-shaped blind plate is blind, and the operating state of the 8-shaped blind plate is open during compressed air purging. During compressed air purging, the bolts between the two flanges are removed, and then the 8-shaped blind plate is rotated 180° and the bolts between the two flanges are installed. At this time, one side of the 8-shaped blind plate iron ring is connected to the first connecting pipe 3, and compressed air can be purged normally through the first connecting pipe 3; when the purging is completed, the bolts between the two flanges are removed again, and the 8-shaped blind plate is rotated 180°. After that, one side of the blind plate on the 8-shaped blind plate seals the first connecting pipe 3, which can prevent ammonia from coming out of the first pipeline, thereby preventing ammonia from overflowing and causing safety problems.

[0027] Ten ammonia injection grids (AIGs) 9 are installed at the entrance of the flue 2 disclosed in this embodiment. The first connecting pipe 3 is connected to each of the ten AIGs 9 via ten second connecting pipes 6. Each second connecting pipe 6 is equipped with a second ball valve 7. This second ball valve 7 is a manual valve for controlling branch compressed air or nitrogen. It is normally closed and opened to purge the AIGs.

[0028] An ammonia injection main pipe is also provided outside the flue, and a third ball valve 8 is provided between the ammonia injection main pipe and each ammonia injection grid 9. The third ball valve 8 is used to control the ammonia gas entering the ammonia injection grid (which can also be said to be the flue).

[0029] The ammonia outlet of the ammonia injection main pipe is connected to an ammonia-air mixer, the outlet of which is connected to 10 groups of ammonia injection grids. A dilution fan is also connected to the ammonia-air mixer.

[0030] When installing the purge system, a compressed air purge pipe can be added to the ammonia injection pipeline of the SCR denitrification device corresponding to each boiler based on existing on-site conditions. Each boiler should be connected to a compressed air source using an SCR sonic soot blower nearby, and the compressed air source pipe should be connected to each ammonia injection grid 9. The function of the sonic soot blower is to convert compressed air into high-power sound waves or infrasound waves (a pressure wave that propagates in a spatial medium in the form of a sparse-dense wave) and send them into the furnace, thereby improving the purge effect.

[0031] In summary, the ammonia spray grid purge system of the SCR denitrification device disclosed by the utility model can use compressed air to purge the ammonia spray grid during boiler operation or after shutdown through an added compressed air source. In addition, an 8-shaped blind plate is provided on the first connecting pipe. The 8-shaped blind plate can prevent ammonia and compressed air media from mutual leakage, thereby avoiding safety problems caused by ammonia overflow. In addition, this cleaning by compressed air source can also avoid manual knocking and dredging, thereby eliminating the risk of falling for the staff working in this project.

[0032] The embodiments described above are only preferred specific implementation methods of the present invention, and the protection scope of the present invention is not limited thereto. Any simple changes or equivalent replacements of the technical solutions that can be obviously obtained by any technician familiar with the field within the technical scope disclosed in the present invention fall within the protection scope of the present invention.

Claims

1. An ammonia injection grid purge system for an SCR denitration device, the SCR denitration device comprising a flue (2), a plurality of ammonia injection grids (9) being arranged at the inlet of the flue (2), characterized in that: The purge system comprises: A compressed air source (1), the air outlet of which is connected to the air inlet of a first connecting pipe (3), and the air outlet of the first connecting pipe (3) is in communication with the ammonia injection grid (9); The gas mutual crosstalk prevention unit comprises two flanges and an 8-shaped blind plate (5) connected to a first connecting pipe (3), wherein the two flanges are connected to the first connecting pipe (3), the 8-shaped blind plate (5) is located between the two flanges, and the 8-shaped blind plate (5) is rotatably connected to one of the flanges via a rotating shaft, and the two flanges are connected via bolts.

2. The ammonia injection grid purge system of an SCR denitrification device according to claim 1, characterized in that: The air outlet of the compressed air source (1) is also connected to a sonic soot blower, and the air outlet of the sonic soot blower is connected to the air inlet of the first connecting pipe (3).

3. The ammonia injection grid purge system of an SCR denitration device according to claim 2, characterized in that: A first ball valve (4) is also provided on the first connecting pipe (3), and the first ball valve (4) is located upstream of the 8-shaped blind plate (5).

4. The ammonia injection grid purge system of an SCR denitrification device according to claim 1, characterized in that: Ten ammonia injection grids (9) are provided at the entrance of the flue, and the first connecting pipe (3) is connected to the ten groups of ammonia injection grids (9) one by one through ten second connecting pipes (6).

5. The ammonia injection grid purge system of an SCR denitration device according to claim 4, characterized in that: Each of the second connecting pipes (6) is provided with a second ball valve (7).

6. The ammonia injection grid purge system of an SCR denitrification device according to claim 1, characterized in that: An ammonia injection main pipe is also provided on the outside of the flue (2), and a third ball valve (8) is also provided between the ammonia injection main pipe and each of the ammonia injection grids (9).

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