Ammonia spraying grating device in SCR (Selective Catalytic Reduction) denitration system

Abstract

The utility model relates to the technical field of denitration systems, in particular to an ammonia spraying grating device in an SCR (Selective Catalytic Reduction) denitration system, which can effectively ensure the denitration efficiency, comprises a flue, and is characterized in that a transversely arranged mother pipe is arranged outside the flue, an ammonia-air mixed gas inlet is formed in the mother pipe, the mother pipe is connected with at least two groups of ammonia spraying assemblies, and the ammonia spraying assemblies are connected with the flue. The ammonia spraying assembly comprises an upper-layer middle transverse pipe and a lower-layer middle transverse pipe, the upper-layer middle transverse pipe is connected with an upper-layer ammonia spraying pipe, the upper-layer ammonia spraying pipe penetrates through the flue wall of the flue and extends to half of the width of the flue, and the lower-layer middle transverse pipe is connected with a lower-layer ammonia spraying pipe; and the lower-layer ammonia spraying pipe penetrates through the flue wall of the flue on one side and extends to the flue wall on the other side.

Description

Technical Field

[0001] The utility model relates to the technical field of denitration systems, and particularly relates to an ammonia injection grid device in an SCR denitration system. Background Art

[0002] In a conventional selective catalytic reduction (SCR) denitration project, the ammonia injection grid is an important component of the ammonia injection system. The diluted gaseous ammonia finally enters the flue through this component of the ammonia injection grid, so that the reducing agent ammonia can be fully mixed with NOx in the flue gas, and a catalytic reduction reaction occurs under the action of a catalyst to generate nitrogen and water. Considering design conditions such as the flue gas flow field, flue cross-section, ammonia consumption, and space layout, there are different ammonia injection grid designs for different furnace types. For the flue cross-section set for large furnace types, the flue width direction is greater than 2 meters, so there is a problem that the injection path of the ammonia injection pipe is too long, and the ammonia quantity distribution in each area injected into the flue is uneven. As a result, the mixing of ammonia and NOx in the flue gas above the top catalyst is uneven, there is a flow field deviation in the denitration efficiency, and the local ammonia escape is too high, affecting the realization of the final denitration efficiency. When the flue gas flow field has a flow deviation, the ammonia injection amounts at the front and rear sides of the same flue cross-section cannot be independently adjusted and controlled to match, so as to adapt to the NOx distribution deviation brought by different working conditions of the flue gas flow field, thus affecting the guarantee of the overall denitration efficiency. Summary of the Invention

[0003] In order to solve the above technical problems, the utility model provides an ammonia injection grid device in an SCR denitration system, which can effectively ensure the denitration efficiency.

[0004] Its technical solution is as follows: an ammonia injection grid device in an SCR denitration system, which includes a flue. It is characterized in that a main pipe arranged horizontally is provided outside the flue, an ammonia-air mixed gas inlet is arranged on the main pipe, the main pipe is connected to at least two groups of ammonia injection components, each ammonia injection component includes an upper middle horizontal pipe and a lower middle horizontal pipe, the upper middle horizontal pipe is connected to an upper ammonia injection pipe, the upper ammonia injection pipe penetrates through the flue wall of the flue and extends to half of the width of the flue, the lower middle horizontal pipe is connected to a lower ammonia injection pipe, and the lower ammonia injection pipe penetrates through the flue wall on one side of the flue and extends to the flue wall on the other side.

[0005] It is further characterized in that the upper middle horizontal pipe and the main pipe, and the lower middle horizontal pipe and the main pipe are respectively communicated through vertical pipes, and a flange butterfly valve and a pressure gauge are installed on the vertical pipes;

[0006] Connecting flanges are installed on both the upper middle horizontal pipe and the lower middle horizontal pipe, and both the upper ammonia injection pipe and the lower ammonia injection pipe are connected to the connecting flanges;

[0007] Support angle steels for supporting the upper ammonia injection pipe and the lower ammonia injection pipe are arranged in the flue;

[0008] A detachable connection mechanism is provided between the upper ammonia injection pipe, the lower ammonia injection pipe and the flue wall of the flue.

[0009] After adopting the present utility model, the upper ammonia injection pipe and the lower ammonia injection pipe with different lengths are arranged in the flue, so that the injected ammonia can be mixed with NOX in the flue gas as evenly as possible, effectively adapting to the possible flow field deviation in the flue gas flow field, improving the adjustability of ammonia injection, and ensuring the denitration efficiency. Description of the Drawings

[0010] Figure 1 It is a schematic structural diagram of the present utility model;

[0011] Figure 2 is Figure 1 schematic view in the direction of A in

[0012] Figure 3 It is a schematic diagram of the detachable connection mechanism. Detailed Embodiment

[0013] See Figures 1 to 3 As shown, an ammonia injection grid device in an SCR denitration system includes a flue 1. A main pipe 2 is arranged horizontally outside the flue 1. According to the length of the flue, two main pipes 2 can be arranged. An ammonia-air mixture inlet 3 is arranged on each main pipe 2. Four groups of ammonia injection components are connected to the lower part of each main pipe. Each group of ammonia injection components includes an upper middle horizontal pipe 4 and a lower middle horizontal pipe 5. The upper middle horizontal pipe 4 is connected to an upper ammonia injection pipe 6. The upper ammonia injection pipe penetrates through the flue wall of the flue 1 and extends to half of the width of the flue 1. The lower middle horizontal pipe 5 is connected to a lower ammonia injection pipe 7. The lower ammonia injection pipe 7 penetrates through the flue wall on one side of the flue 1 and extends to the flue wall on the other side, that is, it is divided into a short ammonia injection pipe and a long ammonia injection pipe.

[0014] The upper middle horizontal pipe 4 and the main pipe 2, and the lower middle horizontal pipe 5 and the main pipe 2 are respectively communicated through a vertical pipe 8. A flange butterfly valve 9 and a pressure gauge 10 are installed on the vertical pipe 8, which can facilitate the adjustment of the air intake volume.

[0015] Support angle steels 11 for supporting the upper ammonia injection pipe 6 and the lower ammonia injection pipe 7 are arranged in the flue 1, which provide anti-wear support for the ammonia injection pipes and also serve as rails for the installation and disassembly of the ammonia injection pipes

[0016] Connecting flanges 12 are installed on both the upper middle horizontal pipe 4 and the lower middle horizontal pipe 5. The upper ammonia injection pipe 6 and the lower ammonia injection pipe 7 are both connected to the connecting flanges; a detachable connection mechanism 13 is provided between the upper ammonia injection pipe 6, the lower ammonia injection pipe 7 and the flue wall of the flue 1. The detachable connection mechanism 13 adopts the structure with the publication number of CN207413156U. For details, see Figure 3, a first opening 131 is formed in the flue duct wall. The upper ammonia injection pipe 6 or the lower ammonia injection pipe 7 passes through the first opening 131. A first straight pipe 132 is welded outside the flue duct wall. A pressing mechanism is welded on the upper ammonia injection pipe 6 or the lower ammonia injection pipe 7. The pressing mechanism includes a second straight pipe 133. The second straight pipe 133 is fixed by a sealing plate 134 welded on the upper ammonia injection pipe 6 or the lower ammonia injection pipe 7. The second straight pipe 133 is sleeved on the first straight pipe 132. An asbestos rope 135 is wound in the area surrounded by the second straight pipe 133, the sealing plate 134 and the ammonia injection pipe. When the second straight pipe 133 is sleeved on the first straight pipe 132 and pressed, the asbestos rope 135 realizes reliable sealing, effectively preventing the substances in the flue duct from leaking out through the gap between the first straight pipe 132 and the ammonia injection pipe. Then the ammonia injection pipe 3 can be conveniently withdrawn or installed on the flue duct wall plate 1 without other operations. When disassembling the ammonia injection pipe, the existing structure can be avoided from being damaged, which is beneficial to the daily maintenance and cleaning of the ammonia injection pipe. When the ammonia injection pipe is inserted and installed on the flue duct wall again, only need to wind the asbestos rope 135 around the ammonia injection pipe again, then insert the ammonia injection pipe into the first opening 131 on the flue duct wall, and press the first straight pipe 132 and the asbestos rope 135, thus ensuring the ammonia injection effect, improving the denitration efficiency, and effectively reducing the cost investment for replacing the ammonia injection pipe.

[0017] This application is applicable to large-size flue duct cross-sections (the width direction of the flue duct is greater than 2 meters). The arranged ammonia injection grids are designed in modules and zones, realizing zone spraying and adjustment of ammonia on the front and back sides of the flue duct, so that the distribution of the injected ammonia and NO in the flue gas X is as evenly matched as possible, effectively adapting to the possible flow field deviation in the flue gas flow field, improving the adjustability of ammonia injection, and ensuring the denitration efficiency. At the same time, two master pipe fittings and multiple ammonia injection modules are set to realize zone spraying and adjustment of ammonia on the left and right sides of the flue duct, further improving the denitration efficiency. Since the space outside the flue duct is narrow and the platform width arrangement is limited, in order to realize the blockage cleaning and disassembly of the ammonia injection pipe, detachable connectors, flanges and flange butterfly valves are used to reduce the disassembly difficulty in the limited space, so as to ensure the efficient, normal and orderly operation of the denitration system.

Claims

1. An ammonia injection grid device in an SCR denitration system, which includes a flue, and is characterized in that, A main pipe arranged horizontally is provided outside the flue. An ammonia-air mixed gas inlet is provided on the main pipe. The main pipe is connected to at least two groups of ammonia injection assemblies. The ammonia injection assembly includes an upper middle horizontal pipe and a lower middle horizontal pipe. The upper middle horizontal pipe is connected to an upper ammonia injection pipe. The upper ammonia injection pipe penetrates through the flue wall of the flue and extends to half of the width of the flue. The lower middle horizontal pipe is connected to a lower ammonia injection pipe. The lower ammonia injection pipe penetrates through the flue wall on one side of the flue and extends to the flue wall on the other side.

2. The ammonia injection grid device in an SCR denitration system according to claim 1, wherein, The upper middle horizontal pipe and the main pipe, and the lower middle horizontal pipe and the main pipe are respectively communicated through vertical pipes. A flange butterfly valve and a pressure gauge are installed on the vertical pipes.

3. The ammonia injection grid device in an SCR denitration system according to claim 1, characterized in that, Connecting flanges are installed on both the upper middle horizontal pipe and the lower middle horizontal pipe. The upper ammonia injection pipe and the lower ammonia injection pipe are both connected to the connecting flanges.

4. The ammonia injection grid device in an SCR denitration system according to claim 1, characterized in that, Support angle steels for supporting the upper ammonia injection pipe and the lower ammonia injection pipe are provided in the flue.

5. The ammonia injection grid device in an SCR denitration system according to claim 1, characterized in that, A detachable connection mechanism is provided between the upper ammonia injection pipe, the lower ammonia injection pipe and the flue wall of the flue.

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