Circular flue denitration ammonia spraying device with simple structure

Abstract

The utility model discloses a round flue denitration ammonia spraying device with a simple structure, which comprises a plurality of ammonia spraying pipes, an ammonia gas cavity, an ammonia gas header pipe, an ammonia gas flow meter and an ammonia gas regulating valve, the ammonia spraying pipes are arranged in the round flue in rows, the ammonia gas cavity is arranged on the side surface of the round flue, input ports of the ammonia spraying pipes are communicated with the ammonia gas cavity, and the ammonia gas flow meter is arranged on the ammonia gas header pipe. Compared with the prior art, the flue gas denitration device has the advantages that the flue gas denitration device can be suitable for a circular flue, the investment cost is reduced, the structure is simple, the denitration efficiency is improved, and the ammonia escape does not exceed the standard.

Description

Technical Field

[0001] This utility model relates to the technical field of flue gas SCR denitrification, and in particular to a simple circular flue denitrification ammonia injection device. Background Technology

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

[0003] In SCR flue gas denitrification devices, the diffusion of ammonia and the uniformity of mixing with flue gas are one of the most critical factors affecting denitrification efficiency. Currently, the injection device in the SCR denitrification process mainly adopts the ammonia injection grid (AIG), which has various forms and structures.

[0004] The ammonia injection grid includes an ammonia inlet main pipe, an ammonia regulating valve, an ammonia flow meter, ammonia branch pipes, an ammonia injection grid device, and nozzles. Diluted ammonia is delivered to the ammonia injection grid device through the ammonia injection pipeline, regulating valve, and metering device. It is then sprayed from the nozzles of the ammonia injection grid into the flue, where it mixes with the flue gas. Finally, it reacts chemically with NOx on the surface of the catalyst. If the ammonia injection grid is poorly designed or the flue gas flow 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 ammonia injection in some areas. This not only wastes a lot of ammonia but also causes a large amount of ammonia to escape, which will seriously damage the environment.

[0005] SCR ammonia injection grilles are generally arranged in square flues, as seen in authorization announcements CN219964513 U ("A Flue Gas Denitrification Ammonia Injection Grille"), CN221385923 U ("SCR Denitrification Ammonia Injection Grille Device"), CN219879563 U ("A Multi-Stage Equal Resistance Ammonia Injection Grille"), CN205796965 U ("A Structure of SCR Denitrification Ammonia Injection Grille for Coal-fired Power Plants"), CN206621995 U ("A Novel Ammonia Injection Grille"), and application publication CN115105938 A ("A High-Efficiency Controlled Ammonia Injection Grille and Ammonia Injection Calculation Method for Flue Gas Denitrification"). These arrangements are based on the dimensions of square flues and are not suitable for circular flues. Annular ammonia injection pipes are also used, as seen in authorization announcement CN218871785. U, “An Ammonia Injection Grid for Uniformly Distributing Airflow in a Denitrification Reactor”, has several layers of ammonia injection annular pipes that are not on the same cross section, but are set with cross sections in the flow velocity direction. The structure is relatively complex, and the distribution of multi-section ammonia injection ports can easily cause flue gas short circuits, resulting in uneven mixing of ammonia gas and flue gas, which reduces denitrification efficiency and causes ammonia escape to exceed the standard.

[0006] Currently, emission requirements in industries such as steel, chemicals, and building materials are becoming increasingly stringent. In particular, for processes like coke oven flue gas denitrification, lime kiln flue gas denitrification, cement flue gas denitrification, and biomass flue gas denitrification, the flue gas volume is relatively small, and ammonia gas is generally generated by evaporating ammonia water as a reducing agent. To reduce investment costs and facilitate flexible flue layout, most flues adopt a circular structure. If a square flue is required for the ammonia injection section during SCR denitrification, two square-round sections need to be installed before and after the original flue. Especially in retrofit projects, there is basically no extra space. Therefore, ammonia injection grid devices suitable for circular flues are needed to meet the outlet emission requirements while achieving a reasonable layout of the process system and reducing investment costs. Summary of the Invention

[0007] The purpose of this invention is to solve the problems in the existing technology and propose a simple circular flue denitrification ammonia injection device that is applicable to circular flues, reduces investment costs, has a simple structure, improves denitrification efficiency, and ensures that ammonia escape does not exceed the standard.

[0008] To achieve the above objectives, this utility model proposes a simple circular flue gas denitrification ammonia injection device, comprising several ammonia injection pipes, an ammonia gas chamber, an ammonia main pipe, an ammonia flow meter, and an ammonia regulating valve. The ammonia injection pipes are arranged in rows inside the circular flue gas. The ammonia gas chamber is provided on the side of the circular flue gas. The inlet of each ammonia injection pipe is connected to the ammonia gas chamber. The ammonia main pipe is connected to the ammonia gas chamber. An ammonia flow meter and an ammonia regulating valve are provided on the ammonia main pipe. Several nozzles are provided on each ammonia injection pipe.

[0009] Preferably, the ammonia nozzles are arranged in three rows (front, middle, and rear) within the circular flue, with adjacent rows of ammonia nozzles staggered.

[0010] Preferably, the row spacing 'a' between two adjacent rows of ammonia nozzles is 250mm to 350mm, and the spacing 'b' between two adjacent ammonia nozzles in the same row is 500mm to 700mm.

[0011] Preferably, the nozzles are arranged in two rows on the back side of the ammonia spray pipe, the nozzle diameter is 8mm to 15mm, the two rows of nozzles are staggered, the stagger angle c is 60° to 120°, and the distance d between two adjacent nozzles in the same row is 100mm to 300mm.

[0012] Preferably, the volume of the ammonia gas chamber is not less than the total volume of ammonia sprayed by all ammonia nozzles (1) per minute.

[0013] Preferably, the length of the ammonia nozzles in the same row decreases from the middle to both sides.

[0014] The beneficial effects of this utility model are as follows: By arranging ammonia gas nozzles in a row inside a circular flue, with an ammonia gas chamber on the side of the flue, the inlets of the ammonia gas nozzles are all connected to the ammonia gas chamber, and the main ammonia gas pipe is connected to the ammonia gas chamber. The main ammonia gas pipe is equipped with an ammonia flow meter and an ammonia gas regulating valve, and the ammonia gas nozzles are equipped with several nozzles. Compared with the prior art, this utility model is applicable to circular flues, reduces investment costs, has a simple structure, improves denitrification efficiency, and ensures that ammonia escape does not exceed the standard.

[0015] The features and advantages of this utility model will be described in detail through embodiments and accompanying drawings. Attached Figure Description

[0016] Figure 1 This is a cross-sectional structural schematic diagram of a simple circular flue denitrification ammonia injection device according to this utility model;

[0017] Figure 2 yes Figure 1 Cross-sectional view of AA in the middle;

[0018] Figure 3 yes Figure 1 Cross-sectional view of BB in the middle;

[0019] Figure 4 This is a schematic diagram of the nozzle arrangement on the ammonia main pipe;

[0020] Figure 5 This is a schematic diagram showing the nozzle positions on the ammonia main pipe.

[0021] In the diagram: 1-Ammonia nozzle, 2-Ammonia chamber, 3-Ammonia main pipe, 4-Ammonia flow meter, 5-Ammonia regulating valve, 6-Circular flue, 7-Nozzle. Detailed Implementation

[0022] See Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 This utility model discloses a simple circular flue gas denitrification ammonia injection device, comprising several ammonia injection pipes 1, ammonia gas chambers 2, an ammonia main pipe 3, an ammonia flow meter 4, and an ammonia regulating valve 5. The ammonia injection pipes 1 are arranged in rows inside the circular flue gas 6. The ammonia gas chambers 2 are provided on the side of the circular flue gas 6. The inlets of the ammonia injection pipes 1 are all connected to the ammonia gas chambers 2. The ammonia main pipe 3 is connected to the ammonia gas chambers 2. The ammonia main pipe 3 is equipped with an ammonia flow meter 4 and an ammonia regulating valve 5. Several nozzles 7 are provided on the ammonia injection pipes 1.

[0023] The ammonia nozzles 1 are arranged in three rows (front, middle, and rear) within the circular flue 6, with adjacent rows of ammonia nozzles 1 staggered.

[0024] The row spacing a between two adjacent rows of ammonia nozzles 1 is 250mm to 350mm, and the spacing b between two adjacent ammonia nozzles 1 in the same row is 500mm to 700mm.

[0025] The nozzles 7 are arranged in two rows on the back side of the ammonia spray pipe 1. The diameter of the nozzles 7 is 8mm to 15mm. The two rows of nozzles 7 are staggered by an angle c of 60° to 120°. The distance d between two adjacent nozzles 7 in the same row is 100mm to 300mm.

[0026] The volume of the ammonia gas chamber 2 is not less than the total volume of ammonia sprayed by all ammonia nozzles (1) per minute.

[0027] The length of the ammonia nozzles 1 in the same row decreases from the middle to both sides.

[0028] The working process of this utility model:

[0029] In the operation of this utility model, a simple circular flue gas denitrification ammonia injection device is introduced into the ammonia gas chamber 2 from the ammonia gas main pipe 3. The ammonia gas flow rate entering the ammonia gas chamber 2 is controlled by the ammonia gas flow meter 4 and the ammonia gas regulating valve 5. The ammonia gas in the ammonia gas chamber 2 enters the ammonia gas injection pipe 1 and is finally evenly injected into the flue gas from the nozzle 7.

[0030] The nozzles 7 are arranged in two rows on the back side of the ammonia spray pipe 1. The diameter of the nozzles 7 is 8mm to 15mm. The two rows of nozzles 7 are staggered by an angle c of 60° to 120°. The distance d between two adjacent nozzles 7 in the same row is 100mm to 300mm, which improves the uniformity of ammonia injection into the circular flue 6 and makes ammonia and flue gas mix evenly.

[0031] Each ammonia nozzle 1 extends directly from the wall of the circular flue 6 to the ammonia chamber 2. Since the volume of the ammonia chamber 2 is not less than the total volume of ammonia sprayed by all ammonia nozzles (1) in one minute, the pressure inside each ammonia nozzle 1 connected to the ammonia chamber 2 is basically the same, and the amount of ammonia sprayed from the nozzle 7 is basically consistent, further ensuring the uniformity of ammonia and flue gas mixing.

[0032] Since the ammonia nozzle 1 is directly connected to the ammonia chamber 2, it avoids the need to equip each ammonia nozzle 1 with an ammonia flow meter and ammonia regulating valve as in conventional configurations. Only one ammonia flow meter and flow regulating valve need to be installed on the ammonia main pipe 3, which greatly saves investment costs while still ensuring denitrification efficiency.

[0033] The ammonia nozzles 1 in the two adjacent rows are staggered to further improve the uniformity of ammonia and flue gas mixing.

[0034] The above embodiments are illustrative of the present invention and are not intended to limit the present invention. Any simple modifications to the present invention are within the protection scope of the present invention.

Claims

1. A simple circular flue gas denitrification ammonia injection device, characterized in that: It includes several ammonia nozzles (1), ammonia gas chambers (2), ammonia main pipe (3), ammonia flow meter (4), and ammonia regulating valve (5). The ammonia nozzles (1) are arranged in rows in a circular flue (6). The ammonia gas chambers (2) are provided on the side of the circular flue (6). The inlets of the ammonia nozzles (1) are all connected to the ammonia gas chambers (2). The ammonia main pipe (3) is connected to the ammonia gas chambers (2). The ammonia main pipe (3) is equipped with an ammonia flow meter (4) and an ammonia regulating valve (5). The ammonia nozzles (1) are provided with several nozzles (7).

2. The simple circular flue gas denitrification ammonia injection device as described in claim 1, characterized in that: The ammonia nozzles (1) are arranged in three rows (front, middle and rear) in the circular flue (6), with the ammonia nozzles (1) in adjacent rows being staggered.

3. The simple circular flue gas denitrification ammonia injection device as described in claim 1, characterized in that: The row spacing a of two adjacent rows of ammonia nozzles (1) is 250mm to 350mm, and the spacing b of two adjacent rows of ammonia nozzles (1) in the same row is 500mm to 700mm.

4. The simple circular flue gas denitrification ammonia injection device as described in claim 1, characterized in that: The nozzles (7) are arranged in two rows on the back side of the ammonia spray pipe (1). The diameter of the nozzles (7) is 8mm to 15mm. The two rows of nozzles (7) are staggered, with a stagger angle c of 60° to 120°. The distance d between two adjacent nozzles (7) in the same row is 100mm to 300mm.

5. The simple circular flue gas denitrification ammonia injection device as described in claim 1, characterized in that: The volume of the ammonia gas chamber (2) is not less than the total volume of ammonia sprayed by all ammonia nozzles (1) per minute.

6. A simple circular flue gas denitrification ammonia injection device according to any one of claims 1 to 5, characterized in that: The length of the ammonia nozzles (1) in the same row decreases from the middle to both sides.

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