SCR (Selective Catalytic Reduction) ammonia injection grid device

Abstract

The invention discloses a selective catalytic reduction (SCR) ammonia spraying grating device which comprises a plurality of ammonia spraying pipes and a vertical flue, the ammonia spraying pipes are horizontally arranged and are arranged into an upper row and a lower row in the vertical flue, and ammonia in every two adjacent ammonia spraying pipes on the same cross section of the vertical flue flows in different directions. Compared with the prior art, the SCR flue gas denitration system has the advantages that the system is more reliable, the spraying uniformity of the ammonia gas can be improved, the efficiency of the SCR flue gas denitration system is improved, the ammonia escape is reduced, and the SCR flue gas denitration system is more environment-friendly. And the structure is simpler than that of a common ammonia spraying grid.

Description

Technical Field

[0001] The invention relates to the technical field of flue gas SCR denitration, in particular to an SCR ammonia injection grid device. Background Art

[0002] Denitrification is the process of removing nitrogen oxides contained in the exhaust gas produced by combustion. The current mainstream flue gas denitrification technology is the SCR denitrification process, which uses ammonia as a reducing agent. Under the action of a catalyst, ammonia reacts with NOx in the flue gas to produce nitrogen and water.

[0003] In the SCR flue gas denitrification device, the degree to which ammonia is injected into the flue gas for diffusion and mixing with NOx in the flue gas is one of the most critical factors affecting the denitrification efficiency. At present, the injection device in the SCR denitrification process mainly adopts ammonia injection grid (AIG), which has various forms and structures.

[0004] The ammonia spray grid includes an ammonia spray air inlet pipeline, an ammonia regulating valve, an ammonia flow meter, an ammonia branch pipe, an ammonia spray grid device and a nozzle, etc. The diluted ammonia is transported to the ammonia spray grid device through the ammonia spray air inlet pipeline, the ammonia regulating valve and the ammonia flow meter, and is sprayed into the flue from the nozzle of the ammonia spray grid to mix with the flue gas, and finally reacts chemically with NOx on the surface of the catalyst. When the ammonia spray grid is improperly designed or the flue gas airflow distribution is unreasonable, it is easy to cause uneven mixing of NOx and NH3, which not only affects the denitrification efficiency, but also causes excessive local ammonia spraying, which not only wastes a lot of ammonia, but also a large amount of ammonia escape will seriously damage the environment.

[0005] SCR inlet zone ammonia injection and outlet zone NOx / NH3 monitoring have become standard. Reasonable ammonia injection grid structure can ensure uniform mixing of reductant and NOx with as few denitrification zones as possible. It can not only reduce investment costs, but also reduce the mutual influence of ammonia injection amount and mixing effect between zones during debugging and operation. System maintenance and operation will become simpler and more reliable. This has become a technical problem that needs to be solved urgently in this field.

[0006] Domestic denitrification manufacturers have conducted a lot of research on different working conditions and applied for a large number of patents. The forms of ammonia spraying grids vary, with varying advantages and disadvantages. For example, in the authorization announcement number CN219964513 U "A flue gas denitrification ammonia spraying grid", when ammonia is sprayed in a deep flue, uneven ammonia spraying is prone to occur; in the authorization announcement number CN221385923 U "SCR denitrification ammonia spraying grid device", the ammonia spraying amount of each nozzle cannot be controlled uniformly; in the authorization announcement number CN219879563 U "A multi-stage equal resistance ammonia spraying grid", although the ammonia spraying branch pipe is designed with equal resistance to make each ammonia spraying amount relatively uniform, the system is very complex and the ammonia spraying pipeline has great resistance; in another example, in the authorization announcement number CN205796965 U "A coal-fired power plant flue gas SCR denitrification ammonia spraying grid structure", the diameter of the ammonia main pipe is reduced along the flow direction, but the local diameter reduction design cannot guarantee uniform ammonia spraying; in another example, in the authorization announcement number CN206621995 U "A new type of ammonia spraying grid" and application publication number CN115105938 A "A flue gas denitrification high-efficiency control ammonia spraying grid and ammonia spraying amount calculation method" cannot ensure that the ammonia spraying amount of the nozzles on the same branch pipe is uniform. If the uniformity of ammonia spraying amount is to be improved, the system will be more complicated and a large number of regulating valves and flow meters will need to be added, which will not only make debugging and operation and maintenance more troublesome, but also greatly increase the investment cost. Summary of the invention

[0007] The purpose of the present invention is to solve the problems in the prior art and to provide an SCR ammonia injection grid device which can improve the uniformity of ammonia injection, thereby improving the efficiency of the SCR flue gas denitrification system and has a simple structure.

[0008] To achieve the above-mentioned purpose, the present invention proposes an SCR ammonia spray grid device, comprising a plurality of ammonia nozzles and a vertical flue, wherein the ammonia nozzles are horizontally arranged and arranged in two rows in the vertical flue, and the ammonia in two adjacent ammonia nozzles on the same cross-section of the vertical flue flows in different directions, and the input ends of the ammonia nozzles are sequentially connected to an ammonia flowmeter and an ammonia regulating valve located outside the flue, and the ammonia nozzles are provided with a plurality of nozzles.

[0009] Preferably, the upper and lower rows of ammonia nozzles are staggered.

[0010] Preferably, the row spacing Z between the upper and lower rows of ammonia nozzles is 400 mm to 600 mm, and the spacing X between two adjacent ammonia nozzles on the same cross section of the flue is 700 mm to 900 mm.

[0011] Preferably, the nozzle is tilted on the back-smoke side of the ammonia nozzle, the nozzle diameter is 10mm-30mm, the tilt directions of two adjacent nozzles are opposite, the angle a formed by two adjacent nozzles is 60°-120°, and the distance Y between two adjacent nozzles is 100-300mm.

[0012] Preferably, a baffle is provided on the smoke-facing side of the ammonia nozzle, and a baffle plate corresponding to the corresponding nozzle is provided on the baffle.

[0013] Beneficial effects of the present invention: The present invention arranges ammonia nozzles horizontally and in two rows in a vertical flue, and ammonia in two adjacent ammonia nozzles on the same cross-section of the flue flows in different directions. The input ends of the ammonia nozzles are sequentially connected to an ammonia flow meter and an ammonia regulating valve outside the flue. The ammonia nozzles are provided with a plurality of nozzles. Compared with the prior art, the system is more reliable and can improve the uniformity of ammonia injection, thereby improving the efficiency of the SCR flue gas denitrification system and reducing ammonia escape. The structure is simpler than a general ammonia injection grid.

[0014] The features and advantages of the present invention will be described in detail through embodiments in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic elevation view of an SCR ammonia injection grid device of the present invention; Figure 2 yes Figure 1 A front view of the middle nozzle being arranged on the ammonia nozzle; Figure 3 This is the layout of the ammonia nozzles in the upper row; Figure 4 This is the layout of the lower row of ammonia nozzles.

[0016] In the figure: 1- ammonia nozzle, 2- vertical flue, 3- ammonia flow meter, 4- ammonia regulating valve, 5- nozzle, 6- baffle, 7- blocking plate. DETAILED DESCRIPTION

[0017] See also Figure 1 , Figure 2 , Figure 3 and Figure 4 The present invention discloses an SCR ammonia spraying grid device, comprising a plurality of ammonia spray pipes 1 and a vertical flue 2. The ammonia spray pipes 1 are arranged horizontally and arranged in two rows in the vertical flue 2. Ammonia in two adjacent ammonia spray pipes 1 on the same cross-section of the flue 2 flows in different directions. The input ends of the ammonia spray pipes 1 are sequentially connected with an ammonia flow meter 3 and an ammonia regulating valve 4 located outside the flue 2. The ammonia spray pipes 1 are provided with a plurality of nozzles 5.

[0018] The upper and lower rows of ammonia nozzles 1 are staggered, and the row spacing Z of the upper and lower rows of ammonia nozzles 1 is 400mm-600mm, and the spacing X between two adjacent ammonia nozzles 1 on the same cross section of the flue 2 is 700mm-900mm.

[0019] The nozzle 5 is tilted on the smoke-repelling side of the ammonia nozzle 1, the diameter of the nozzle 5 is 10 mm to 30 mm, the tilt directions of two adjacent nozzles 5 are opposite, the angle a formed by two adjacent nozzles 5 is 60° to 120°, and the distance Y between two adjacent nozzles 5 is 100 to 300 mm.

[0020] The smoke-facing side of the ammonia nozzle 1 is provided with a baffle 6 , and the baffle 6 is provided with a blocking sheet 7 corresponding to the corresponding nozzle 5 one by one.

[0021] Working process of the present invention: In the working process of the SCR ammonia spraying grid device of the present invention, ammonia gas enters the ammonia spray pipe 1, and then the ammonia gas is sprayed into the flue uniformly through the nozzle 5.

[0022] Each ammonia nozzle 1 is single-side end air intake. Since the ammonia nozzle 1 is of equal cross-section, the injection amount of the nozzle 5 along its air intake length direction will gradually increase. In order to ensure that the ammonia injection amount in each area of ​​the flue 2 is basically uniform, the ammonia in two adjacent ammonia nozzles 1 on the same cross-section of the flue 2 is used to flow in different directions, ensuring that the ammonia injection amount in each area of ​​the flue gas is basically the same. In addition, an ammonia flowmeter 3 and an ammonia regulating valve 4 are separately configured on each ammonia nozzle 1 to ensure that the flow rate of any ammonia nozzle 1 is basically consistent, thereby improving the uniformity of ammonia injection, thereby improving the efficiency of the SCR flue gas denitrification system, and the structure is simple, which can ensure that ammonia escape does not exceed the standard, and at the same time significantly reduce the investment cost.

[0023] The row spacing Z of the upper and lower rows of ammonia nozzles 1 is 400mm-600mm, the spacing X between two adjacent ammonia nozzles 1 on the same cross section of the flue 2 is 700mm-900mm, the nozzle 5 is tilted on the back-to-smoke side of the ammonia nozzle 1, the diameter of the nozzle 5 is 10mm-30mm, the tilt directions of two adjacent nozzles 5 are opposite, the angle a formed by two adjacent nozzles 5 is 60°-120°, and the spacing Y between two adjacent nozzles 5 is 100-300mm, which further improves the uniformity of ammonia injection and improves the denitrification efficiency.

[0024] The above embodiments are intended to illustrate the present invention, not to limit the present invention. Any solution that is a simple transformation of the present invention belongs to the protection scope of the present invention.

Claims

1. An SCR ammonia injection grid device, characterized in that: The invention comprises a plurality of ammonia nozzles (1) and a vertical flue (2), wherein the ammonia nozzles (1) are arranged horizontally and arranged in two rows in the vertical flue (2), and ammonia in two adjacent ammonia nozzles (1) on the same cross section of the vertical flue (2) flows in different directions, and the input ends of the ammonia nozzles (1) are sequentially connected to an ammonia flow meter (3) and an ammonia regulating valve (4) located outside the vertical flue (2), and the ammonia nozzles (1) are provided with a plurality of nozzles (5).

2. The SCR ammonia injection grid device according to claim 1, characterized in that: The upper and lower rows of ammonia nozzles (1) are arranged alternately.

3. The SCR ammonia injection grid device according to claim 2, characterized in that: The row spacing Z between two adjacent rows of ammonia nozzles (1) is 400 mm to 600 mm, and the spacing X between two adjacent ammonia nozzles (1) on the same cross section of the vertical flue (2) is 700 mm to 900 mm.

4. The SCR ammonia injection grid device according to claim 1, characterized in that: The nozzle (5) is arranged obliquely on the smoke-repelling side of the ammonia nozzle (1), the diameter of the nozzle (5) is 10 mm to 30 mm, the inclination directions of two adjacent nozzles (5) are opposite, the angle a formed by the two adjacent nozzles (5) is 60° to 120°, and the distance Y between the two adjacent nozzles (5) is 100 to 300 mm.

5. An SCR ammonia injection grid device according to any one of claims 1 to 4, characterized in that: The smoke-facing side of the ammonia nozzle (1) is provided with a baffle (6), and the baffle (6) is provided with a baffle sheet (7) corresponding to the corresponding nozzle (5) one by one.

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