Precise ammonia spraying system
By designing an accurate ammonia injection system in SCR denitrification equipment, using cyclone, ammonia injection grille and NOx sensor to achieve uniform mixing of ammonia and flue gas, the problem of insufficient accuracy of ammonia injection quantity control in the prior art is solved, which improves denitrification efficiency and reduces the risk of equipment failure.
Patent Information
- Application Number
- CN202422721121.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-08
- Publication Date
- 2025-06-27
- Estimated Expiration
- 2034-11-08
AI Technical Summary
It is difficult for existing SCR denitrification equipment to achieve uniform mixing of ammonia and flue gas during ammonia spraying, resulting in limited accuracy of ammonia spraying quantity control, affecting denitrification efficiency and increasing the risk of equipment failure.
An accurate ammonia injection system is designed. By setting a cyclone, ammonia injection grille and vertical guide plate in the vertical section smoke pipe, combined with the monitoring of the inlet and outlet NOx sensors, the ammonia injection amount is accurately calculated, and the ammonia injection amount is adjusted through multiple independent ammonia injection areas to achieve uniform mixing of ammonia and flue gas.
The uniform mixing of ammonia and flue gas is achieved, the accuracy of control of ammonia spraying is improved, the denitrification efficiency of SCR equipment is improved, and the equipment failure rate is reduced.
Smart Images
Figure CN223027088U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of denitration equipment, and particularly to a precise ammonia injection system. Background Art
[0002] Denitration technology is a treatment technology for removing NOx from flue gas. Based on the current strict NOx emission requirements, the selective catalytic reduction (SCR) denitration technology is widely used in various heavily polluting emission units such as thermal power plants and cement kilns due to its relatively high denitration efficiency. The principle of the selective catalytic reduction (SCR) denitration technology is that ammonia (NH3) reacts with NOx in the flue gas under the action of a catalyst to generate harmless nitrogen and water. The amount of ammonia injection is closely related to the denitration efficiency. Too little ammonia injection will lead to insufficient ammonia, which will in turn affect the denitration efficiency; too much ammonia injection will cause the amount of ammonia to exceed the reaction amount, which will lead to ammonia escape. The escaped ammonia will react with SO3 in the high-temperature flue gas to form ammonium salts attached to the equipment, which will in turn cause equipment failures.
[0003] In the prior art, there have been many studies on the precise ammonia supply for SCR equipment, and there are mainly two ways to achieve precise ammonia supply. The first is to monitor the denitration efficiency of the system and at the same time monitor the ammonia escape parameter, and control the ammonia injection amount according to the monitoring results; the second is to monitor the NOx concentration at the inlet and outlet of the flue gas of the system, calculate the theoretical ammonia demand according to the formula, and then correct it according to the actual denitration efficiency to calculate the actual ammonia demand, and control the ammonia injection amount according to the calculation results. The first method is limited by the mixing uniformity of the flue gas and ammonia and the fluctuation of the NOx concentration in the flue gas, and the accuracy is limited; the second method is also limited by the mixing uniformity of the flue gas and ammonia, and there is a certain error in the calculation result, and the accuracy is also limited. Summary of the Invention
[0004] In order to solve at least one of the above technical problems, and to develop an ammonia injection system that can effectively mix ammonia and flue gas evenly, and can supply ammonia to the SCR equipment more precisely, while ensuring a relatively high denitration efficiency of the equipment and reducing the equipment failure rate, this application provides a precise ammonia injection system.
[0005] The present application provides a precise ammonia injection system. The ammonia injection system includes an inclined section of a flue gas pipe connected to a flue gas inlet and a vertical section of a flue gas pipe connected to the inclined section of the flue gas pipe. The vertical section of the flue gas pipe is connected to an SCR reactor through a pipeline. A cyclone, an ammonia injection grid, and a vertical deflector are fixedly arranged in the vertical section of the flue gas pipe in sequence from bottom to top. The ammonia injection system further includes an inlet NOx sensor installed in the flue gas inlet and an outlet NOx sensor installed in the flue gas outlet of the SCR reactor. The ammonia injection grid includes a main ammonia injection pipe, at least two ammonia injection branch pipes are fixedly arranged on the main ammonia injection pipe, and a plurality of multi-port nozzle assemblies are evenly installed on the ammonia injection branch pipes. A separate ammonia injection control valve is provided on each ammonia injection branch pipe, so that each ammonia injection branch pipe forms an independent ammonia injection area.
[0006] Optionally, the number of blades of the cyclone is 16 to 18.
[0007] Further optionally, the blade inclination angle of the cyclone is 35° to 40°.
[0008] Optionally, an inclined section deflector is provided at the connection of the inclined section of the flue gas pipe and the vertical section of the flue gas pipe.
[0009] Further optionally, the inclined section deflector is an arc-shaped deflector.
[0010] Optionally, the ammonia injection system further includes a reactor inlet deflector provided at the inlet pipeline of the SCR reactor, and the reactor inlet deflector is an arc-shaped deflector.
[0011] Optionally, there are two sets of the ammonia injection grids, which are symmetrically arranged in the vertical section of the flue gas pipe.
[0012] Further optionally, each ammonia injection branch pipe is provided with 6 to 8 multi-port nozzle assemblies.
[0013] Further optionally, the multi-port nozzle assembly has 6 to 8 nozzles.
[0014] Optionally, the included angle between the inclined section of the flue gas pipe and the horizontal plane is 40° to 50°.
[0015] In summary, the present invention includes at least one of the following beneficial technical effects:
[0016] 1. The ammonia injection system adopted in the present application reforms the flue gas pipeline. The flue gas pipeline is changed to a pipeline composed of a section of inclined pipeline and a section of vertical pipeline spliced together, and the ammonia injection grid is arranged in the vertical section of the pipeline. The present application also arranges the cyclone, the ammonia injection grid, and the vertical deflector in the vertical section of the flue gas pipe, which is beneficial to controlling the flue gas flow rate and effectively making the ammonia and the flue gas mix evenly.
[0017] 2. NOx sensors are installed at both the flue gas inlet and the flue gas outlet of this application, which can effectively monitor the NOx concentration at the inlet and outlet, and then accurately calculate the actual denitration efficiency. According to the actual denitration efficiency, the ammonia injection amount can be calculated using a formula, and then the ammonia injection flow rate can be precisely controlled.
[0018] 3. The ammonia injection grid of this application adopts a design of a main pipe cooperating with branch pipes, dividing the ammonia injection grid into multiple independent ammonia injection zones. The ammonia and flue gas can be further effectively mixed evenly by adjusting the ammonia injection amount in each ammonia injection zone. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 is a schematic structural diagram of the precise ammonia injection system of this application;
[0020] Figure 2 is a schematic structural diagram of the ammonia injection grid of this application;
[0021] Figure 3 is a schematic structural diagram of the ammonia injection grid in Embodiment 3 of this application;
[0022] In the figure: 1, flue gas inlet; 2, inclined section flue gas pipe; 3, vertical section flue gas pipe; 4, ammonia injection grid; 41, ammonia injection main pipe; 42, ammonia injection branch pipe; 43, multi-orifice nozzle assembly; 5, cyclone; 6, vertical deflector; 7, inclined section deflector; 8, SCR reactor; 9, reactor inlet deflector; 10, inlet NOx sensor; 11, outlet NOx sensor. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0023] The following further describes this application in detail with reference to the drawings and embodiments.
[0024] As Figure 1 shown, this application designs a precise ammonia injection system, which includes an inclined section flue gas pipe 2 connected to the flue gas inlet 1 and a vertical section flue gas pipe 3 connected to the inclined section flue gas pipe 2. The vertical section flue gas pipe 3 is connected to the SCR reactor 8 through a pipeline. The connecting pipeline between the inclined section flue gas pipe 2 and the vertical section flue gas pipe 3 can adopt an arc-shaped pipe; the vertical section flue gas pipe 3 can be connected to a horizontal pipe through an arc-shaped pipe, and then the horizontal pipe is connected to the SCR reactor 8. The included angle between the inclined section flue gas 2 and the horizontal plane is preferably set to 40° - 50°.
[0025] The ammonia injection system further includes an inlet NOx sensor 10 installed in the flue gas inlet 1 and an outlet NOx sensor 11 installed in the flue gas outlet of the SCR reactor 8, which are used to monitor the NOx concentration, so as to realize the real-time monitoring of the actual denitration efficiency.
[0026] A cyclone 5, an ammonia injection grid 4, and a vertical deflector 6 are fixedly arranged in sequence from bottom to top in the vertical section flue gas pipe 3.
[0027] like Figure 2 As shown, the ammonia injection grid 4 includes an ammonia injection main pipe 41, on which at least two ammonia injection branch pipes 42 are fixedly arranged, and on which a plurality of multi-port nozzle assemblies 43 are evenly installed, and each ammonia injection branch pipe 42 is provided with a separate ammonia injection control valve. The ammonia injection control valve adopts a solenoid valve, which can be controlled by electric control so that the ammonia injection assembly included in each ammonia injection branch pipe 42 forms an independent ammonia injection area. The ammonia injection main pipe 41 can be arranged on the outside of the vertical section smoke pipe 3, and the ammonia injection branch pipe 42 passes through the outer wall of the vertical section smoke pipe 3, and the main ammonia injection part of the ammonia injection grid 4 is located in the vertical section smoke pipe 3. The ammonia injection control valve is arranged outside the vertical section smoke pipe 3 for easy maintenance and replacement.
[0028] The actual ammonia injection amount of the present application can be calculated based on the parameters monitored by the inlet NOx sensor 10 to obtain the theoretical ammonia requirement m0, and then the actual ammonia requirement can be calculated using a formula.
[0029] The specific formula is as follows:
[0030] m = m0 × ((K + K0) / 2K);
[0031] Among them, K is the actual denitrification efficiency, and K0 is the designed maximum denitrification efficiency of the denitrification system.
[0032] The present application divides the ammonia injection grid 4 into multiple independent ammonia injection zones, and can adjust the ammonia injection amount of each ammonia injection zone according to the monitoring result of the concentration monitoring component of the SCR reactor 8, so that the flue gas concentration entering the SCR reactor 8 is relatively uniform.
[0033] The following are examples of the present application:
[0034] Example 1
[0035] The structure of this embodiment is basically similar to the main solution of this application.
[0036] The angle between the inclined section smoke pipe 2 of the precision ammonia injection system of this embodiment and the horizontal plane is 45°.
[0037] The number of blades of the cyclone 5 of this embodiment is 16 to 18, and the blade inclination angle of the cyclone 5 can be set to any value between 35° and 40°, preferably 38°.
[0038] In this embodiment, each ammonia injection branch pipe 42 can be provided with 6 to 8 multi-port nozzle assemblies 43, and each multi-port nozzle assembly 43 can be provided with 6 to 8 nozzles.
[0039] Example 2
[0040] The structure of this embodiment is basically similar to that of Embodiment 1, except that a guide plate is additionally provided.
[0041] At the connection of the inclined section flue pipe 2 and the vertical section flue pipe 3 in this embodiment, an inclined section deflector 7 is provided, and the inclined section deflector 7 is an arc-shaped deflector.
[0042] The ammonia injection system in this embodiment also sets a reactor inlet deflector 9 at the inlet pipeline of the SCR reactor 8, and the reactor inlet deflector 9 is also an arc-shaped deflector.
[0043] After adding the deflector in this embodiment, the flow rate of the flue gas in the flue can be made more appropriate, and the distribution of the flue gas is more uniform.
[0044] Embodiment 3
[0045] The structure of this embodiment is basically similar to that of Embodiment 2, and the difference lies in the structure of the ammonia injection grid 4.
[0046] As Figure 3 shown, two ammonia injection grids 4 are provided in this embodiment, which are symmetrically arranged in the vertical section flue pipe 3.
[0047] Each ammonia injection main pipe 41 in this embodiment is provided with 5 ammonia injection branch pipes 42, so that 10 ammonia injection areas are arranged in the entire vertical section flue pipe 3, which is convenient for precise control of ammonia injection and makes the mixing of flue gas and ammonia injection more uniform.
[0048] Perform performance detection on the precise ammonia injection system of Embodiments 1 to 3 of the present application, and the specific detection process is as follows.
[0049] Install the precise ammonia injection systems of Embodiments 1 to 3 on a 630MW coal-fired unit respectively and operate at peak load for 30 days. The SCR reactors 8 configured by the precise ammonia injection systems of Embodiments 1 to 3 all adopt reactors with a designed maximum denitration efficiency of 95%.
[0050] Detect the denitration efficiency and ammonia slip concentration, detect every day, and take the average value of the results.
[0051] The obtained detection data are shown in Table 1 below.
[0052] Table 1 Performance detection data of Embodiments 1 to 4
[0053] Denitrification efficiency (%) Ammonia slip concentration (μL / L) Example 1 93.8 2.9 Example 2 94.3 2.5 Example 3 94.6 2.1
[0054] It can be seen from the data in Table 1 that by using the precise ammonia injection systems of Embodiments 1 to 3 of the present application, the denitration system has a relatively high denitration efficiency, and the ammonia slip concentration can be controlled within 3 μL / L, which can greatly reduce system failures.
[0055] The above are all preferred embodiments of the present application. The protection scope of the present application is not limited accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application should be covered within the protection scope of the present application.
Claims
1. A precision ammonia injection system, characterized in that: The ammonia injection system comprises an inclined section smoke pipe (2) connected to a flue gas inlet (1) and a vertical section smoke pipe (3) connected to the inclined section smoke pipe (2), wherein the vertical section smoke pipe (3) is connected to an SCR reactor (8) through a pipeline; a cyclone (5), an ammonia injection grid (4) and a vertical guide plate (6) are fixedly arranged in sequence from bottom to top in the vertical section smoke pipe (3); the ammonia injection system also comprises an inlet NOx sensor (10) installed in the flue gas inlet (1), and an outlet NOx sensor (11) installed in the flue gas outlet of the SCR reactor (8); the ammonia injection grid (4) comprises an ammonia injection main pipe (41), at least two ammonia injection branch pipes (42) are fixedly arranged on the ammonia injection main pipe (41), a plurality of multi-port nozzle assemblies (43) are evenly installed on the ammonia injection branch pipe (42), and each ammonia injection branch pipe (42) is provided with a separate ammonia injection control valve, so that each ammonia injection branch pipe (42) forms an independent ammonia injection area.
2. The precise ammonia injection system according to claim 1, characterized in that: The number of blades of the cyclone (5) is 16 to 18.
3. The precise ammonia injection system according to claim 2, characterized in that: The blade inclination angle of the cyclone (5) is 35° to 40°.
4. The precise ammonia injection system according to claim 1, characterized in that: An inclined section guide plate (7) is provided at the connection between the inclined section smoke pipe (2) and the vertical section smoke pipe (3).
5. The precise ammonia injection system according to claim 4, characterized in that: The inclined section guide plate (7) is an arc-shaped guide plate.
6. The precise ammonia injection system according to claim 1, characterized in that: The ammonia injection system further comprises a reactor inlet guide plate (9) arranged at an inlet pipeline of the SCR reactor (8), wherein the reactor inlet guide plate (9) is an arc-shaped guide plate.
7. The precise ammonia injection system according to claim 1, characterized in that: The ammonia injection grids (4) are provided in two groups and are symmetrically arranged in the vertical section of the smoke pipe (3).
8. The precise ammonia injection system according to claim 7, characterized in that: Each ammonia injection branch pipe (42) is provided with 6 to 8 multi-port nozzle assemblies (43).
9. The precise ammonia injection system according to claim 8, characterized in that: The multi-orifice nozzle assembly (43) has 6 to 8 nozzles.
10. The precise ammonia injection system according to claim 1, characterized in that: The angle between the inclined smoke pipe section (2) and the horizontal plane is 40° to 50°.