Round flue denitration ammonia injection grid capable of uniformly distributing airflow

Abstract

The utility model discloses a circular flue denitration ammonia injection grid for uniformly distributing air flow, which comprises a plurality of air inlet pipelines, a plurality of annular ammonia gas mother pipes, a plurality of ammonia gas flow regulating valves and a plurality of ammonia gas flow meters, the diameters of the annular ammonia gas mother pipes are different, the annular ammonia gas mother pipes are positioned on the same section of the circular flue and are concentrically arranged, and the ammonia gas flow regulating valves are communicated with the ammonia gas flow meters. The annular ammonia gas main pipes are communicated with the ammonia gas main pipe through at least one gas inlet pipeline, ammonia gas flow regulating valves and ammonia gas flow meters are arranged on the gas inlet pipelines, and a plurality of nozzles are formed in the annular ammonia gas main pipes. And 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 circular flue gas denitrification ammonia injection grid with uniformly distributed airflow. 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 and uniformity of ammonia after being injected into the flue and its mixing with the flue gas are among 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 injection inlet pipeline, an ammonia flow regulating valve, an ammonia metering device, an ammonia branch pipe, an ammonia injection grid device, and nozzles. Diluted ammonia is delivered to the ammonia injection grid device through the ammonia injection inlet pipeline, the ammonia flow regulating valve, and the 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 prior art by proposing a circular flue gas denitrification ammonia injection grid with uniform airflow, which is applicable to circular flues, reduces investment costs, improves denitrification efficiency, and ensures that ammonia escape does not exceed the standard.

[0008] To achieve the above objectives, this utility model proposes a circular flue gas denitrification ammonia injection grid with uniform airflow, comprising several inlet pipes, several annular ammonia main pipes, several ammonia flow regulating valves, and several ammonia flow meters. Each of the annular ammonia main pipes has a different diameter. The annular ammonia main pipes are located on the same cross section of the circular flue and are concentrically arranged. Each annular ammonia main pipe is connected to the ammonia main pipe through at least one inlet pipe. Each inlet pipe is equipped with an ammonia flow regulating valve and an ammonia flow meter. Each annular ammonia main pipe is equipped with several nozzles.

[0009] Preferably, except for the annular ammonia main pipe near the center of the circular flue, the remaining annular ammonia main pipes are equipped with several partition plates to evenly divide them into multiple sealed cavities, and each sealed cavity is connected to the ammonia main pipe through an air inlet pipe.

[0010] Preferably, the nozzle is located on the back side of the annular ammonia main pipe, the nozzle diameter is 8mm to 15mm, adjacent nozzles are staggered, the stagger angle α is 60° to 120°, and the distance b between adjacent nozzles is 50mm to 150mm.

[0011] Preferably, the radius difference between two adjacent annular ammonia headers is no greater than 700 mm.

[0012] The beneficial effects of this utility model are as follows: Each annular ammonia gas header has a different diameter, and the annular ammonia gas headers are located on the same cross section of the circular flue and are concentrically arranged. Each annular ammonia gas header is connected to the main ammonia gas pipe through at least one inlet pipe. Each inlet pipe is equipped with an ammonia gas flow regulating valve and an ammonia gas flow meter. Each annular ammonia gas header is equipped with several nozzles. Compared with the prior art, it can be applied to circular flues, reduce investment costs, improve denitrification efficiency, and ensure that ammonia escape does not exceed the standard.

[0013] The features and advantages of this utility model will be described in detail through embodiments and accompanying drawings. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of a circular flue gas denitrification ammonia injection grid with uniformly distributed airflow according to this utility model;

[0015] Figure 2 yes Figure 1 Sectional view of AA;

[0016] Figure 3 This is a schematic diagram showing that two adjacent nozzles are staggered.

[0017] In the diagram: 1-Inlet pipe, 2-Annular ammonia main pipe, 3-Ammonia flow regulating valve, 4-Ammonia flow meter, 5-Circular flue, 6-Ammonia main pipe, 7-Nozzle, 8-Divider plate. Detailed Implementation

[0018] See Figure 1 , Figure 2 , Figure 3 This utility model discloses a circular flue gas denitrification ammonia spray grid with uniform airflow, comprising several inlet pipes 1, several annular ammonia main pipes 2, several ammonia flow regulating valves 3, and several ammonia flow meters 4. Each of the annular ammonia main pipes 2 has a different diameter. The annular ammonia main pipes 2 are located on the same cross section of the circular flue gas 5 and are concentrically arranged. Each annular ammonia main pipe 2 is connected to the ammonia main pipe 6 through at least one inlet pipe 1. Each inlet pipe 1 is equipped with an ammonia flow regulating valve 3 and an ammonia flow meter 4. Each annular ammonia main pipe 2 is equipped with several nozzles 7.

[0019] Except for the annular ammonia main pipe 2 located near the center of the circular flue 5, the remaining annular ammonia main pipes 2 are equipped with several partition plates 8 to evenly divide them into multiple sealed cavities. Each sealed cavity is connected to the ammonia main pipe 6 through an air inlet pipe 1.

[0020] The nozzle 7 is located on the back side of the annular ammonia main pipe 2. The diameter of the nozzle 7 is 8mm to 15mm. Two adjacent nozzles 7 are staggered, with a stagger angle a of 60° to 120° and a distance b of 50mm to 150mm between them.

[0021] The radius difference between two adjacent annular ammonia main pipes 2 is no greater than 700 mm.

[0022] The working process of this utility model:

[0023] In the operation of the circular flue gas denitrification ammonia spraying grid with uniform airflow of this utility model, the air inlet pipe 1 introduces ammonia gas from the ammonia gas main pipe 6, and the ammonia gas flow rate entering the corresponding annular ammonia gas header 2 is controlled by the ammonia gas flow regulating valve 3 and the ammonia gas flow meter 4. The ammonia gas in the annular ammonia gas header 2 is evenly sprayed into the flue gas through the nozzle 7.

[0024] The annular ammonia main pipe 2 is equipped with several partition plates 8, which evenly divide it into multiple sealed chambers. Each sealed chamber is connected to the ammonia main pipe 6 through an air inlet pipe 1 to avoid air mixing, ensure that the air intake of each independent chamber is constant and that the flow rate of any nozzle is basically consistent, thereby further improving the denitrification efficiency and reducing ammonia escape and investment costs.

[0025] The nozzle 7 is located on the back side of the annular ammonia main pipe 2. The diameter of the nozzle 7 is 8mm to 15mm. Two adjacent nozzles 7 are staggered, with a stagger angle a of 60° to 120° and a distance b of 50mm to 150mm between them. This further improves the uniformity of mixing ammonia and nitrogen oxides in the flue gas and enhances the efficiency of the SCR flue gas denitrification system.

[0026] 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 circular flue gas denitrification ammonia injection grid with uniformly distributed airflow, characterized in that: It includes several air inlet pipes (1), several annular ammonia main pipes (2), several ammonia flow regulating valves (3) and several ammonia flow meters (4). Each of the annular ammonia main pipes (2) has a different diameter. The annular ammonia main pipes (2) are located on the same cross section of the circular flue (5) and are arranged concentrically. Each of the annular ammonia main pipes (2) is connected to the ammonia main pipe (6) through at least one air inlet pipe (1). Each air inlet pipe (1) is equipped with an ammonia flow regulating valve (3) and an ammonia flow meter (4). Each of the annular ammonia main pipes (2) is equipped with several nozzles (7).

2. The circular flue gas denitrification ammonia injection grid with uniformly distributed airflow as described in claim 1, characterized in that: Except for the annular ammonia main pipe (2) near the center of the circular flue (5), the remaining annular ammonia main pipes (2) are provided with several partition plates (8) to evenly divide them into multiple sealed cavities. Each sealed cavity is connected to the ammonia main pipe (6) through an air inlet pipe (1).

3. The circular flue gas denitrification ammonia injection grid with uniformly distributed airflow as described in claim 1, characterized in that: The nozzle (7) is located on the back side of the annular ammonia main pipe (2). The diameter of the nozzle (7) is 8mm to 15mm. Two adjacent nozzles (7) are staggered, with a stagger angle a of 60° to 120° and a distance b of 50mm to 150mm between them.

4. A circular flue gas denitrification ammonia injection grid with uniformly distributed airflow as described in any one of claims 1 to 3, characterized in that: The radius difference between two adjacent annular ammonia main pipes (2) shall not exceed 700 mm.

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