Ammonia injection device, ammonia injection equipment and ammonia injection method

Abstract

The present invention relates to the technical field of coal-fired flue gas denitration, and discloses an ammonia injection device, an ammonia injection equipment and an ammonia injection method. The ammonia injection device comprises an ammonia injection branch pipe (1), the ammonia injection branch pipe (1) is composed of a plurality of gradually shortened pipes which are telescopically connected, the diameter of the ammonia injection branch pipe (1) gradually decreases along the flow direction of ammonia in the ammonia injection branch pipe (1), and a plurality of ammonia injection holes (2) are provided on each of the gradually shortened pipes. The ammonia injection device has a simple structure and is easy to assemble, and can greatly even out the amount of ammonia injected from each ammonia injection hole on the ammonia injection branch pipe, thereby improving the ammonia injection effect.

Description

Technical Field

[0001] This invention relates to the field of flue gas denitrification technology, specifically to an ammonia injection device, ammonia injection equipment, and ammonia injection method. Background Technology

[0002] Currently, ammonia injection units for flue gas denitrification in coal-fired power plants generally use ammonia injection grids. Traditional ammonia injection grids mainly consist of several parallel ammonia injection branch pipes, each with several nozzles of uniform size for ammonia injection. According to Bernoulli's principle, as ammonia flows through the injection branch pipes, its static pressure gradually increases along the flow direction. The amount of ammonia injected from the injection holes depends on the hole size, the static pressure of the ammonia before the hole, and the static pressure of the space after the hole. Therefore, traditional ammonia injection grids easily cause uneven ammonia injection from each hole, making control difficult. To achieve the desired ammonia-NOx reaction within the denitrification unit... x For uniform mixing, the ammonia injection device must be able to uniformly inject ammonia from each nozzle on a single ammonia injection branch pipe and adjust the amount of ammonia injected into different areas of the flue.

[0003] Patent application CN 205796965 U discloses a flue gas SCR denitrification ammonia injection grid structure for coal-fired power plants. This device adopts a variable diameter ammonia injection branch pipe structure and enhances the formation of vortices through nozzle cover plates to promote the mixing of ammonia and flue gas. However, this patent solution only focuses on the control of the overall ammonia injection amount in different branch pipes and cannot guarantee the uniformity of ammonia injection amount in different ammonia injection holes in the same branch pipe.

[0004] Therefore, there is an urgent need to improve the pipe structure of the ammonia injection grid to achieve better mixing results. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem in the prior art that it is difficult to guarantee the uniformity of ammonia injection volume from different ammonia injection holes in the same branch pipe during coal-fired flue gas denitrification, and to provide an ammonia injection device. This ammonia injection device has a simple structure and is easy to assemble. It can greatly uniformly distribute the amount of ammonia gas injected from each ammonia injection hole on the ammonia injection branch pipe, thereby improving the ammonia injection effect.

[0006] To achieve the above objectives, the present invention provides an ammonia injection device, which includes an ammonia injection branch pipe. The ammonia injection branch pipe is composed of multiple stages of gradually shortening tubes that are telescopically connected together. The diameter of the ammonia injection branch pipe gradually decreases along the flow direction of ammonia gas in the ammonia injection branch pipe, and each stage of the gradually shortening tube is provided with multiple ammonia injection holes.

[0007] Preferably, multiple ammonia injection holes are symmetrically arranged on the gradually shortening tube.

[0008] Preferably, the multiple ammonia injection holes are arranged symmetrically from left to right along the diameter direction of the gradually shortening tube.

[0009] Preferably, the jet direction of the ammonia injection hole is perpendicular to the flue gas flow direction during coal-fired flue gas denitrification.

[0010] Preferably, adjacent tapered tubes are connected by a threaded connection.

[0011] Preferably, the smaller diameter end of each tapered tube is formed with an internal thread, and the larger diameter end of each tapered tube is formed with an external thread.

[0012] Preferably, each tapered tube has a constricted end with a smaller diameter and a flared end with a larger diameter.

[0013] Preferably, there are multiple ammonia injection branch pipes, and these multiple ammonia injection branch pipes are arranged in a straight line, spiral, or ring configuration.

[0014] A second aspect of the present invention provides an ammonia injection device, which includes an ammonia gas pipeline and the aforementioned ammonia injection apparatus connected to the ammonia gas pipeline.

[0015] A third aspect of the present invention provides an ammonia injection method, which includes performing a nitrogen injection operation using the aforementioned ammonia injection equipment.

[0016] Through the above technical solution, this invention fully considers the influence of the static pressure distribution of ammonia gas in the ammonia injection branch pipe on the ammonia flow direction and the amount of ammonia injected into each injection hole. By improving the existing ammonia injection branch pipe structure, the branch pipe is composed of multiple stages of progressively shortened tubes that are telescopically connected. The diameter of the branch pipe gradually decreases along the flow direction of ammonia gas within it, and multiple injection holes are provided on each stage of the shortened tube. This results in a more uniform static pressure distribution of ammonia gas within the branch pipe, facilitating consistent ammonia gas output from each injection hole and avoiding the uneven ammonia gas output caused by the gradual increase in static pressure along the flow direction in traditional ammonia injection devices. Simultaneously, the multiple shortened tubes can be mutually extended and adjusted, allowing independent adjustment of the number of shortened tube stages in each branch pipe based on its position within the main injection pipe. This enhances the ammonia injection device's ability to adjust the amount of ammonia injected into different areas of the flue along the main injection pipe direction. Attached Figure Description

[0017] Figure 1 This is a top view schematic diagram of an ammonia injection device provided according to the present invention;

[0018] Figure 2 This is a cross-sectional view of an ammonia injection device provided according to the present invention.

[0019] Explanation of reference numerals in the attached figures

[0020] 1-Ammonia injection branch pipe 2-Ammonia injection hole Detailed Implementation

[0021] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0022] In this invention, unless otherwise stated, directional terms such as "inner," "outer," "left," and "right" included in the terminology represent only the orientation of the term in its normal use or are common terms understood by those skilled in the art, and should not be regarded as limitations on the term.

[0023] See Figure 1 and Figure 2 The present invention provides an ammonia injection device, which includes multiple ammonia injection branch pipes 1. Each ammonia injection branch pipe 1 is composed of multiple stages of gradually shortened pipes that are telescopically connected. The diameter of the ammonia injection branch pipe 1 gradually decreases along the flow direction of ammonia gas in the ammonia injection branch pipe 1. Furthermore, each stage of the gradually shortened pipe is provided with multiple ammonia injection holes 2.

[0024] This invention fully considers the influence of the static pressure distribution of ammonia gas within the ammonia injection branch pipe on the ammonia flow direction and the amount of ammonia injected into each injection hole. By improving the existing ammonia injection branch pipe structure, the branch pipe is composed of multiple stages of progressively shortened tubes that are telescopically connected. The diameter of the branch pipe gradually decreases along the flow direction of ammonia gas within it, and multiple injection holes are formed on each stage of the shortened tube. This results in a more uniform static pressure distribution of ammonia gas within the branch pipe, facilitating consistent ammonia gas output from each injection hole and avoiding the uneven ammonia gas output caused by the gradual increase in static pressure along the flow direction in traditional ammonia injection devices. Furthermore, the telescopic nature of the multiple shortened tubes allows for independent adjustment of the number of shortened tube stages in each branch pipe based on its position within the main injection pipe, enhancing the ammonia injection device's ability to regulate the amount of ammonia injected into different areas of the flue along the main injection pipe direction.

[0025] In this embodiment, in order to ensure that the amount of ammonia gas sprayed from the multiple ammonia injection holes 2 is more uniform during the use of the ammonia injection device, preferably, the multiple ammonia injection holes 2 are symmetrically arranged on the gradually shortening tube.

[0026] Furthermore, in order to ensure that the ammonia gas ejected from the multiple ammonia injection holes 2 can be evenly injected into the entire cross-section of the flue and to maximize the ammonia gas ejection area, it is preferable that the multiple ammonia injection holes 2 are arranged symmetrically on the left and right sides along the diameter direction of the gradually shortening tube.

[0027] Furthermore, when the denitrification reducing agent (i.e., ammonia) is injected into the flue, in order to ensure that the denitrification reducing agent and the flue gas are in full contact during the flue gas denitrification process, the ammonia injection mixing distance is reduced, and the denitrification reaction effect is optimized, preferably, the jet direction of the ammonia injection hole 2 is perpendicular to the flue gas flow direction during coal-fired flue gas denitrification.

[0028] In addition, to facilitate quick assembly and disassembly between multi-stage tapered tubes, simplify the operation, and save installation time, it is preferable to connect adjacent tapered tubes via threaded connection.

[0029] Simultaneously, each tapered tube has an internal thread at the smaller diameter end and an external thread at the larger diameter end. When installing a multi-stage tapered tube system, the thinner tapered tube is inserted into the wider end of the thicker tapered tube and pushed forward. Since the diameter of the wider end of the thinner tapered tube is smaller than that of the wider end of the thicker tapered tube, but larger than that of the narrower end, the narrower end of the thicker tapered tube will prevent the thinner tapered tube from advancing further, and the two will not detach. At this point, the thinner and thicker tapered tubes are rotated in opposite directions. The internal thread at the narrower end of the thicker tapered tube engages with the external thread at the wider end of the thinner tapered tube, securing them together. Furthermore, the connection is sealed to prevent ammonia leakage from the joint.

[0030] When installing the thinner and thicker tapered tubes, if their ends have conventional cross-sections, any collision during installation will result in hard contact, easily leading to deformation or even damage to the ends. Deformed ends will affect the assembly between the thinner and thicker tapered tubes, while damaged ends will compromise the seal at the joint after installation. This will cause ammonia gas used for flue gas denitrification to leak from the joint, negating the original uniform ammonia injection function of the device. To solve these technical problems, preferably, each tapered tube has a constriction at the smaller diameter end and a flare at the larger diameter end. Using constriction and flare not only prevents excessive movement during assembly from causing the thinner and thicker tapered tubes to detach, but also protects the connection area from deformation or damage during hard collisions, effectively ensuring a tight seal after connection.

[0031] When this ammonia injection device is used for precision ammonia injection, numerical simulation calculations are required based on the actual conditions of the flue to determine the arrangement and position of the branch pipes, such as in-line, spiral, or circular arrangements. Furthermore, the orifice size of the ammonia injection branch pipes can be adjusted based on the calculation results.

[0032] The present invention also provides an ammonia injection device, which includes an ammonia pipeline and the aforementioned ammonia injection apparatus connected to the ammonia pipeline. In use, the ammonia gas in the ammonia pipeline enters the ammonia injection branch pipe 1, passes through the ammonia injection reducing branch pipes of each stage in sequence, and is evenly injected out through the ammonia injection holes 2, so that the denitrification reducing agent (ammonia) is evenly injected into the entire flue cross section.

[0033] Furthermore, by adjusting the length of the ammonia injection short pipes at different positions of the ammonia injection branch pipe 1, the number of short pipe stages of the ammonia injection branch pipe 1 at different positions can be controlled, thereby enhancing the ammonia injection device's ability to adjust the amount of ammonia injected into different areas of the flue along the direction of the ammonia injection main pipe.

[0034] In addition, the present invention also provides an ammonia injection method for denitrification of industrial boilers and large coal-fired boilers. The method uses the above-mentioned ammonia injection equipment to perform nitrogen injection operation, so as to achieve uniform ammonia injection volume between ammonia injection holes of different stages and within ammonia injection holes of the same stage short pipe during the ammonia injection process, thereby reducing the ammonia injection mixing distance and ensuring denitrification efficiency.

[0035] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various specific technical features in any suitable manner. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. However, these simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An ammonia injection device, characterized in that: The ammonia injection device comprises an ammonia injection branch pipe (1), the ammonia injection branch pipe (1) is composed of a plurality of gradually shortened pipes which are telescopically connected, the diameter of the ammonia injection branch pipe (1) gradually decreases along the flow direction of ammonia gas in the ammonia injection branch pipe (1), and a plurality of ammonia injection holes (2) are opened on each of the gradually shortened pipes; A constriction is formed at one end with a smaller diameter on each of the tapered shortening tubes, and a flare is formed at one end with a larger diameter; the flare end of the thinner tapered shortening tube has a smaller diameter than the flare end of the thicker tapered shortening tube, and is larger than the constriction end of the thicker tapered shortening tube, and the constriction and the flare are used to protect the connection area between the thinner tapered shortening tube and the thicker tapered shortening tube when they collide with each other; The adjacent tapered shortened tubes are connected by threaded fitting; An end with a smaller diameter on each of the tapered shortened tubes is formed with an internal thread, and an end with a larger diameter on each of the tapered shortened tubes is formed with an external thread.

2. The ammonia injection device according to claim 1, characterized in that: A plurality of ammonia injection holes (2) are symmetrically arranged on the tapered shortened tube.

3. The ammonia injection device according to claim 2, characterized in that: The plurality of ammonia injection holes (2) are symmetrically arranged along the diameter direction of the tapered tube.

4. The ammonia injection device according to claim 3, characterized in that: The jetting direction of the ammonia jet hole (2) is perpendicular to the flue gas flow direction during denitration of the coal-fired flue gas.

5. The ammonia injection device according to claim 1, characterized in that: The ammonia injection branch pipes (1) are multiple and the multiple ammonia injection branch pipes (1) are arranged in a straight line, spiral or surrounding manner.

6. An ammonia spraying device, characterized in that: The ammonia injection equipment comprises an ammonia pipeline and an ammonia injection device according to any one of claims 1 to 5 connected to the ammonia pipeline.

7. An ammonia injection method, characterized in that: The ammonia injection method comprises using the ammonia injection equipment according to claim 6 to perform an ammonia injection operation.

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