A device for adjusting the inlet flue gas temperature of an SCR of a pulverized coal boiler

Abstract

The utility model relates to the technical field of SCR entrance flue gas temperature regulation, especially to a kind of SCR entrance flue gas temperature regulation device for pulverized coal boiler, which effectively improves the inlet flue gas temperature of SCR denitration device, ensures that denitration catalyst has higher reaction activity, improves denitration efficiency, simple structure, reasonable in design, convenient to use;Including main flue, second main flue, SCR denitration device, first adjusting component, second adjusting component and temperature detection component, second main flue is connected with main flue, SCR denitration device is connected with second main flue, first adjusting component is installed in main flue interior, second adjusting component is installed between main flue and second main flue, temperature detection component is installed in main flue and second main flue interior.

Description

Technical Field

[0001] This utility model relates to the technical field of SCR inlet flue gas temperature regulation, and in particular to an SCR inlet flue gas temperature regulation device for pulverized coal boilers. Background Technology

[0002] With increasingly stringent national environmental protection requirements, a series of effective measures have been implemented to control boiler exhaust emissions. One such effective measure is the adoption of Selective Catalytic Reduction (SCR) technology, commonly known as SCR denitrification. SCR denitrification devices are typically installed in the boiler tail flue, and the permissible operating temperature range for the SCR catalyst is generally 300-410℃. When the boiler load decreases, the flue gas temperature of the SCR denitrification device at the boiler tail also decreases. When the boiler load falls below 35% BMCR, there is a risk that the flue gas temperature of the SCR denitrification device at the boiler tail may drop below its minimum permissible operating temperature of 300℃. For example, the prior art announcement CN204648200U proposes a boiler economizer capable of controlling the SCR inlet flue gas temperature. This economizer includes heat exchange pipes, an inlet header and an outlet header connected to the inlet and outlet of the heat exchange pipes. The inlet header is connected to a cold water pipe, and the outlet header is connected to a hot water pipe. Two intersecting but non-communicating pipes are added between the cold water pipe and the hot water pipe, namely a first connecting pipe and a second connecting pipe. Controllable valves are installed on these pipes. When the economizer is operating at high or low load, the direction of water flow in the pipes is changed by controlling the opening and closing of the controllable valves, thereby controlling the temperature drop of the flue gas in the economizer and controlling the SCR inlet flue gas temperature to ensure that the SCR inlet flue gas remains within the optimal reaction temperature range of the denitrification catalyst. However, if the system can adjust the SCR inlet flue gas temperature when it is too high, it cannot adjust the SCR inlet flue gas temperature when it is too low. Conversely, if it can adjust the SCR inlet flue gas temperature when it is too low, it cannot adjust the SCR inlet flue gas temperature when it is too high. In other words, it cannot adjust the SCR inlet flue gas temperature under full load conditions. Utility Model Content

[0003] To solve the above-mentioned technical problems, this utility model provides an SCR inlet flue gas temperature regulating device for pulverized coal boilers that effectively increases the inlet flue gas temperature of the SCR denitrification device, ensures that the denitrification catalyst has high reactivity, improves denitrification efficiency, has a simple structure, reasonable design, and is easy to use.

[0004] This utility model discloses an SCR inlet flue gas temperature regulating device for pulverized coal boilers, comprising a main flue, a second main flue, an SCR denitrification device, a first regulating component, a second regulating component, and a temperature detection component. The second main flue is connected to the main flue, and the SCR denitrification device is connected to the second main flue. The first regulating component is installed inside the main flue, and the second regulating component is installed between the main flue and the second main flue. The temperature detection component is installed inside both the main flue and the second main flue. This device can effectively recover waste heat, thereby reducing the unit's coal consumption for power generation and improving the unit's economy. It achieves full-load operation temperature regulation of the SCR denitrification device inlet flue gas temperature. It can effectively improve SCR denitrification efficiency, extend the service life of the SCR denitrification catalyst, and reduce the emission concentration of pollutants such as NOx under high or low load conditions. It has a simple structure, reasonable design, and is easy to use.

[0005] Preferably, the first regulating component includes a first economizer, a first electrically controlled valve, a second pre-economizer, and a second electrically controlled valve. The first economizer is installed on the upper side of the main flue, and the second pre-economizer is installed inside the main flue below the first economizer. The first electrically controlled valve is installed at the input end of the first economizer, and the second electrically controlled valve is installed at the input end of the second pre-economizer. The first and second pre-economizers are connected to the boiler feedwater. The first and second economizers regulate the inlet flue gas temperature of the SCR denitrification device by preheating the boiler feedwater. When the inlet flue gas temperature of the SCR denitrification device is too high, the first and second electrically controlled valves are opened. The boiler feedwater is preheated by the first economizer and then flows into the second pre-economizer for further heating, which increases the heat exchange of the inlet flue gas of the SCR denitrification device and can effectively reduce the inlet flue gas temperature of the SCR denitrification device, thereby ensuring that the denitrification catalyst has high reactivity and improving the denitrification efficiency.

[0006] Preferably, the second regulating component includes a bypass flue, a second gate valve, and a regulating baffle. The input end of the bypass flue is connected to the interior of the main flue and is located above the first economizer. The output end of the bypass flue is connected to the interior of the second main flue. A second gate valve is installed at the input end of the bypass flue, and a regulating baffle is installed at the output end of the bypass flue. When the inlet flue temperature of the SCR denitrification device is too low, the first and second electrically controlled valves are closed, and the second gate valve is opened. Some of the coal smoke enters the bypass flue. By adjusting the opening of the regulating baffle, the flow rate of the coal smoke is controlled, thereby regulating the flue temperature flowing to the inlet of the SCR denitrification device.

[0007] Preferably, the temperature detection component includes a first temperature measuring rod, a second temperature measuring rod, and a third temperature measuring rod. The detection end of the first temperature measuring rod is located inside the main flue, between the first economizer and the second pre-economizer. The second temperature measuring rod is installed at the inlet of the SCR denitrification device, and the third temperature measuring rod is installed inside the main flue near the SCR denitrification device. The first temperature measuring rod detects the flue gas temperature passing through the first economizer, while the third temperature measuring rod detects the flue gas temperature about to enter the SCR denitrification device, facilitating timely adjustment of the second electrically controlled valve. The second temperature measuring rod can detect the flue gas temperature at the inlet of the SCR denitrification device, ensuring optimal reaction conditions.

[0008] Preferably, it also includes a gate valve, a central flue, and a third gate valve. The gate valve is installed inside the main flue, located between the first economizer and the second pre-economizer. The central flue connects the main flue and the bypass flue. The third gate valve is installed inside the central flue. When the flue gas temperature after heat exchange in the first economizer is at the required temperature, the gate valve is closed and the third gate valve is opened, allowing the flue gas to enter the bypass flue through the central flue and then directly enter the second main flue, thereby precisely controlling the flue gas temperature.

[0009] Preferably, it also includes a low-temperature preheater and a control valve. The low-temperature preheater is installed in the main flue, and the control valve is installed at the input end of the low-temperature preheater. The low-temperature preheater can recover residual heat, thereby reducing the coal consumption for power generation and improving the economic efficiency of the unit.

[0010] Preferably, an insulation layer is provided on the inner wall of the bypass flue; the insulation layer can improve the insulation effect of the bypass flue and reduce heat loss when the inlet flue temperature of the SCR denitrification device is too low.

[0011] Compared with the prior art, the beneficial effects of this utility model are as follows: it can effectively realize waste heat recovery, thereby reducing the coal consumption of the unit for power generation and improving the economic efficiency of the unit; it can realize the full-load operation condition regulation of the inlet flue gas temperature of the SCR denitrification device; it can effectively improve the SCR denitrification efficiency, extend the service life of the SCR denitrification catalyst, and reduce the emission concentration of pollutants such as NOx under high load or low load conditions of the unit; it has a simple structure, reasonable design, and is easy to use. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a schematic diagram of the isometric structure of this utility model; Figure 3 This is a front view structural diagram of the present invention; Figure 4 This is a front cross-sectional structural diagram of the present invention; Figure 5This is a partial cross-sectional structural schematic diagram of the present invention; The following are labels in the attached diagram: 1. Main flue; 2. Second main flue; 3. SCR denitrification device; 4. First economizer; 5. First electrically controlled valve; 6. Gate valve; 7. Second pre-economizer; 8. Second electrically controlled valve; 9. First temperature measuring rod; 10. Bypass flue; 11. Second gate valve; 12. Adjusting baffle; 13. Second temperature measuring rod; 14. Central flue; 15. Third gate valve; 16. Third temperature measuring rod; 17. Low-temperature preheater; 18. Control valve; 19. Insulation layer. Detailed Implementation

[0013] To facilitate understanding of this utility model, a more complete description will be given below with reference to the accompanying drawings. This utility model can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of this utility model more thorough and complete.

[0014] like Figures 1 to 5 As shown, the second main flue 2 is connected to the main flue 1, the SCR denitrification device 3 is connected to the second main flue 2, the first economizer 4 is installed on the upper side of the main flue 1, and the second pre-economizer 7 is installed inside the main flue 1 below the first economizer 4. A first electrically controlled valve 5 is installed at the input end of the first economizer 4, and a second electrically controlled valve 8 is installed at the input end of the second pre-economizer 7. The first economizer 4 and the second pre-economizer 7 are connected to the boiler feedwater. The input end of the bypass flue 10 communicates with the interior of the main flue 1 and is located above the first economizer 4. The output end of the bypass flue 10 communicates with the interior of the second main flue 2. A second gate valve 11 is installed at the input end of the bypass flue 10, and a second gate valve 11 is installed at the output end of the bypass flue 10. Equipped with an adjusting baffle 12, the first temperature measuring rod 9 is located inside the main flue 1, between the first economizer 4 and the second pre-economizer 7, the second temperature measuring rod 13 is installed at the inlet of the SCR denitrification device 3, the third temperature measuring rod 16 is installed inside the main flue 1 near the SCR denitrification device 3, the gate valve 6 is installed inside the main flue 1, between the first economizer 4 and the second pre-economizer 7, the intermediate flue 14 is connected between the main flue 1 and the bypass flue 10, the third gate valve 15 is installed inside the intermediate flue 14, the low-temperature preheater 17 is installed inside the main flue 1, the input end of the low-temperature preheater 17 is equipped with a control valve 18, and the inner wall of the bypass flue 10 is provided with a heat insulation layer 19; The first economizer 4 and the second pre-economizer 7 regulate the inlet flue gas temperature of the SCR denitrification device 3 by preheating the boiler feedwater. When the inlet flue gas temperature of the SCR denitrification device 3 is too high, the first solenoid valve 5 and the second solenoid valve 8 are opened. The boiler feedwater is preheated by the first economizer 4 and then flows into the second pre-economizer 7 for further heating, increasing the heat exchange of the inlet flue gas of the SCR denitrification device 3. This effectively reduces the inlet flue gas temperature of the SCR denitrification device 3, ensuring that the denitrification catalyst has high reactivity and improving denitrification efficiency. When the inlet flue gas temperature of the SCR denitrification device 3 is too low, the first solenoid valve 5 and the second solenoid valve 8 are closed, and the second gate valve 11 is opened. Some of the flue gas enters the bypass flue duct 10. By adjusting the opening of the regulating baffle 12, the flow rate of the flue gas is controlled, thus regulating the flue gas temperature flowing to the inlet of the SCR denitrification device 3. The first temperature measuring rod 9 detects the flue gas temperature after passing through the first economizer 4, while the third temperature measuring rod 16 detects the flue gas temperature about to enter the SCR denitrification unit 3, facilitating timely adjustment of the second electric control valve 8. The second temperature measuring rod 13 can detect the flue gas temperature at the inlet of the SCR denitrification unit 3 to ensure optimal reaction conditions. When the flue gas temperature after heat exchange in the first economizer 4 is at the required temperature, the gate valve 6 is closed and the third gate valve 15 is opened, allowing the flue gas to enter the bypass flue 10 through the central flue 14 and then directly into the second main flue 2, thereby precisely controlling the flue gas temperature. The low-temperature preheater 17 can recover the remaining heat, thereby reducing the unit's coal consumption for power generation and improving the unit's economy. The insulation layer 19 can improve the insulation effect of the bypass flue 10 and reduce heat loss when the inlet flue gas temperature of the SCR denitrification unit 3 is too low.

[0015] like Figures 1 to 5As shown, this utility model discloses an SCR inlet flue gas temperature regulating device for a pulverized coal boiler. During operation, when the inlet flue gas temperature of the SCR denitrification device 3 is too high, the first solenoid valve 5 and the second solenoid valve 8 are opened. Boiler feedwater is preheated by the first economizer 4 and then flows into the second pre-economizer 7 for further heating, increasing the heat exchange of the inlet flue gas of the SCR denitrification device 3 and effectively reducing its inlet flue gas temperature. The first temperature measuring rod 9 detects the flue gas temperature passing through the first economizer 4, while the third temperature measuring rod 16 detects the flue gas temperature about to enter the SCR denitrification device 3, facilitating timely adjustment of the second solenoid valve 8. The second temperature measuring rod 13 can monitor the temperature of the SCR denitrification device 3. The inlet flue gas temperature is monitored to ensure optimal reaction conditions. When the inlet flue gas temperature of the SCR denitrification unit 3 is too low, the first solenoid valve 5 and the second solenoid valve 8 are closed, and the second gate valve 11 is opened, allowing some of the flue gas to enter the bypass flue 10. By adjusting the opening of the regulating baffle 12, the flow rate of the flue gas is controlled, thereby regulating the flue gas temperature flowing to the inlet of the SCR denitrification unit 3. When the flue gas temperature after heat exchange in the first economizer 4 is at the required temperature, the gate valve 6 is closed, and the third gate valve 15 is opened, allowing the flue gas to enter the bypass flue 10 through the central flue 14 and then directly into the second main flue 2, thereby precisely controlling the flue gas temperature. The remaining heat can be recovered through the low-temperature preheater 17.

[0016] The first economizer 4, gate valve 6, second pre-economizer 7, first temperature measuring rod 9, second gate valve 11, regulating baffle 12, second temperature measuring rod 13, third gate valve 15, third temperature measuring rod 16, and low-temperature preheater 17 of the SCR inlet flue gas temperature regulating device for pulverized coal boiler of this utility model are commercially available. Technical personnel in this industry only need to install and operate them according to the accompanying instruction manual, without requiring any creative work from those skilled in the art.

[0017] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. An SCR inlet flue gas temperature regulating device for pulverized coal boilers, characterized in that, It includes a main flue (1), a second main flue (2), an SCR denitrification device (3), a first regulating component, a second regulating component, and a temperature detection component. The second main flue (2) is connected to the main flue (1), the SCR denitrification device (3) is connected to the second main flue (2), the first regulating component is installed inside the main flue (1), the second regulating component is installed between the main flue (1) and the second main flue (2), and the temperature detection component is installed inside the main flue (1) and the second main flue (2).

2. The SCR inlet flue gas temperature regulating device for a pulverized coal boiler as described in claim 1, characterized in that, The first regulating component includes a first economizer (4), a first electric control valve (5), a second pre-economizer (7), and a second electric control valve (8). The first economizer (4) is installed on the upper side of the main flue (1), and the second pre-economizer (7) is installed inside the main flue (1) below the first economizer (4). The first electric control valve (5) is installed at the input end of the first economizer (4), and the second electric control valve (8) is installed at the input end of the second pre-economizer (7). The first economizer (4) and the second pre-economizer (7) are connected to the boiler feedwater.

3. The SCR inlet flue gas temperature regulating device for a pulverized coal boiler as described in claim 2, characterized in that, The second regulating component includes a bypass flue (10), a second gate valve (11), and a regulating baffle (12). The input end of the bypass flue (10) is connected to the inside of the main flue (1) and is located above the first economizer (4). The output end of the bypass flue (10) is connected to the inside of the second main flue (2). The input end of the bypass flue (10) is equipped with a second gate valve (11), and the output end of the bypass flue (10) is equipped with a regulating baffle (12).

4. The SCR inlet flue gas temperature regulating device for a pulverized coal boiler as described in claim 1, characterized in that, The temperature detection components include a first temperature measuring rod (9), a second temperature measuring rod (13), and a third temperature measuring rod (16). The detection end of the first temperature measuring rod (9) is located inside the main flue (1) between the first economizer (4) and the second pre-economizer (7). The second temperature measuring rod (13) is installed at the inlet of the SCR denitrification device (3). The third temperature measuring rod (16) is installed inside the main flue (1) near the SCR denitrification device (3).

5. The SCR inlet flue gas temperature regulating device for a pulverized coal boiler as described in claim 3, characterized in that, It also includes a gate valve (6), a central flue (14) and a third gate valve (15). The gate valve (6) is installed inside the main flue (1) and located between the first economizer (4) and the second pre-economizer (7). The central flue (14) is connected between the main flue (1) and the bypass flue (10). The third gate valve (15) is installed inside the central flue (14).

6. The SCR inlet flue gas temperature regulating device for a pulverized coal boiler as described in claim 1, characterized in that, It also includes a low-temperature preheater (17) and a control valve (18). The low-temperature preheater (17) is installed in the main flue (1), and the control valve (18) is installed at the input end of the low-temperature preheater (17).

7. The SCR inlet flue gas temperature regulating device for a pulverized coal boiler as described in claim 3, characterized in that, The inner wall of the bypass flue (10) is provided with a heat insulation layer (19).

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