Boiler flue heat exchange device and flue reconstruction method

Abstract

This invention proposes a boiler flue heat exchange device and a flue modification method. The boiler flue heat exchange device of this invention includes: a furnace; a flue, comprising a first flue section, a second flue section, and a third flue section, the upper middle part of the third flue section having at least one set of flue gas outlets, each set of flue gas outlets including multiple flue gas outlets, at least a portion of which are spaced apart vertically; a heat exchanger, disposed in the flue, at least a portion of which is located within the third flue section and below the flue gas outlets; a denitrification reactor, the inlet of which is connected to the outlet at the lower end of the third flue section; and a flue gas regulating unit, comprising multiple first pipes, second pipes, and a flue gas regulating device, the flue gas regulating device being used to regulate the flow rate of flue gas discharged from the second pipes. Therefore, the boiler flue heat exchange device according to this invention can easily maintain the flue gas temperature within the denitrification reactor and reduce the amount of ammonia injected.

Description

Technical Field

[0001] This invention relates to the field of boiler technology, specifically to a boiler flue heat exchange device and a flue modification method. Background Technology

[0002] In related technologies, boiler units require deep peak shaving to maintain a low load, such as 35% or 30% of the rated load. On the one hand, the high outlet steam temperature of the low-temperature superheater often results in insufficient margin for the primary desuperheating water. When the unit needs to increase the load, the tube walls of the partition screen superheater and the rear screen superheater are prone to overheating. If the main steam pressure is increased first and then the load is increased slowly, the speed of load increase will be severely affected. On the other hand, whenever the unit is operating at a low load during deep peak shaving, it is difficult to reach the specified value for the inlet flue gas temperature of the SCR denitrification reactor, which is more obvious in winter. If the inlet flue gas temperature of the SCR denitrification reactor is increased by increasing the air supply, the oxygen content in the furnace will increase significantly, which will lead to a significant increase in the NOx concentration and particulate matter at the SCR denitrification inlet. To avoid environmental over-emissions, it is necessary to increase ammonia injection and electrostatic precipitator power, resulting in multiple energy consumptions. In addition, if the flue gas temperature of the SCR denitrification reactor is too low, the inlet flue gas temperature of the downstream flue gas cooler will also be too low. In order to ensure that the outlet flue gas temperature of the flue gas reheater meets the requirements, a large amount of auxiliary steam can only be put into heating, which will put some pressure on the demineralized water production (including external heating). Summary of the Invention

[0003] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose a boiler flue heat exchange device and a flue modification method.

[0004] The boiler flue heat exchange device of this invention includes: Furnace; The flue includes a first flue section, a second flue section, and a third flue section. The flue gas outlet of the furnace, the first flue section, the second flue section, and the third flue section are connected sequentially. The first flue section and the third flue section extend vertically, and the second flue section extends horizontally. The first flue section includes a flame deflector section, which connects the first flue section and the second flue section. The upper middle part of the third flue section is provided with at least one set of flue gas outlets. Each set of flue gas outlets includes multiple flue gas outlets, and at least a portion of the multiple flue gas outlets are spaced apart vertically. A heat exchanger is disposed in the flue, at least a portion of which is located within the third flue section and below the flue gas outlet. A denitrification reactor, wherein the inlet of the denitrification reactor is connected to the outlet at the lower end of the third flue section; The flue gas regulating unit includes multiple first pipelines, second pipelines, and a flue gas regulating device. The inlets of the multiple first pipelines are connected one-to-one with the multiple flue gas outlets, and the outlets of the multiple first pipelines are connected to the second pipelines. The outlets of the second pipelines are connected to the inlet of the denitrification reactor, so that the flue gas discharged from the second pipelines enters the inlet of the denitrification reactor. The flue gas regulating device is used to regulate the flow rate of the flue gas discharged from the second pipelines.

[0005] Therefore, the boiler flue heat exchange device according to the embodiments of the present invention can facilitate the maintenance of flue gas temperature in the denitrification reactor and reduce the amount of ammonia injected.

[0006] In some embodiments, the heat exchanger includes a horizontal low-temperature superheater and a vertical low-temperature superheater, both of which are located within the third flue section. The vertical low-temperature superheater is located above the horizontal low-temperature superheater, and the inlet at the lower end of the vertical low-temperature superheater is connected to the outlet at the upper end of the horizontal low-temperature superheater. The horizontal cryogenic superheater includes multiple heat exchange tube sections that are spaced apart in the vertical direction and extend in the horizontal direction. The vertical cryogenic superheater includes heat exchange tube sections extending in the vertical direction. At least a portion of the plurality of flue gas outlets are located in the vertical direction between the upper and lower ends of the horizontal cryogenic superheater; and / or At least a portion of the plurality of flue gas outlets are located between the upper and lower ends of the vertical cryogenic superheater in the vertical direction.

[0007] In some embodiments, each group of flue gas outlets includes a first flue gas outlet and a second flue gas outlet, or each group of flue gas outlets includes a first flue gas outlet, a second flue gas outlet and a third flue gas outlet. The first flue gas outlet is located between the upper and lower ends of the vertical low-temperature superheater in the vertical direction; The second flue gas outlet is located in the middle of the horizontal low-temperature superheater in the vertical direction; The third flue gas outlet is located in the middle of the horizontal low-temperature superheater in the vertical direction.

[0008] In some embodiments, the heat exchanger further includes a partition screen superheater, a rear screen superheater, a final stage superheater, and an economizer, wherein the horizontal low-temperature superheater, the vertical low-temperature superheater, the partition screen superheater, the rear screen superheater, and the final stage superheater are connected in sequence. The partition screen superheater and the rear screen superheater are located within the first flue section; The final stage superheater is located within the second flue section; The economizer is located within the third flue section and is located below the horizontal low-temperature superheater; The denitrification reactor, air preheater, and flue gas cooler are connected in sequence.

[0009] In some embodiments, there are multiple sets of flue gas outlets and multiple flue gas regulating devices, with each set of flue gas outlets connected to the denitrification reactor through one of the multiple flue gas regulating devices.

[0010] In some embodiments, the flue gas regulating device includes a first temperature measuring unit, a first manual valve, a pressure measuring unit, an electric regulating valve, a flue gas flow meter, and a second manual valve. The first temperature measuring unit, the first manual valve, the pressure measuring unit, the electric regulating valve, the flue gas flow meter, and the second manual valve are sequentially arranged on the second pipeline in a direction away from the first pipeline.

[0011] In some embodiments, the second pipeline is provided with a flue gas bypass connected thereto. The inlet of the flue gas bypass is located between the first temperature measuring unit and the first manual valve in the extension direction of the second pipeline. The outlet of the flue gas bypass is located between the second manual valve and the outlet of the second pipeline in the extension direction of the second pipeline. The flue gas bypass is provided with a third manual valve. The second pipeline is connected to the denitrification reactor through multiple third pipelines. The third pipelines extend into the denitrification reactor and are spaced apart. The denitrification reactor is provided with multiple spaced-apart third temperature measuring units.

[0012] In some embodiments, the first flue section and the third flue section are arranged side by side in a first horizontal direction; The flue gas outlet is in two sets, and the two sets of flue gas outlets are respectively located on both sides of the third flue section in the second horizontal direction. Any two of the first horizontal direction, the second horizontal direction, and the vertical direction are perpendicular to each other. The flue gas regulating device is used to regulate the flow rate of the flue gas discharged from the second pipeline and to ensure that the temperature of the flue gas entering the denitrification reactor is greater than or equal to 300°C.

[0013] In some embodiments, the flue gas outlet is the opening left by removing the steam soot blower at least one of the parts of the third flue section corresponding to the horizontal low-temperature superheater and the vertical low-temperature superheater. The flue gas regulating device is used to regulate the flow rate of the flue gas discharged from the second pipeline and to ensure that the temperature of the flue gas entering the denitrification reactor is greater than or equal to 305°C and less than or equal to 315°C.

[0014] The present invention also proposes a flue gas modification method, comprising the following steps: removing at least a portion of a plurality of steam soot blowers corresponding to at least one of the horizontal low-temperature superheater and the vertical low-temperature superheater on the flue gas duct; using the opening left by removing the steam soot blowers on the flue gas duct as a flue gas outlet; connecting the flue gas outlet to the inlet of the denitrification reactor through the flue gas regulating section; the flue gas regulating section is used to regulate the temperature of the flue gas introduced into the denitrification reactor. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a boiler flue heat exchange device according to an embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram of a flue gas conditioning device according to an embodiment of the present invention.

[0017] Figure label: 1. Flue; 11. First flue section; 111. Flame deflector section; 12. Second flue section; 13. Third flue section; 14. First flue gas outlet; 15. Second flue gas outlet; 16. Third flue gas outlet. 21. Horizontal low-temperature superheater; 22. Vertical low-temperature superheater; 23. Partition screen superheater; 24. Rear screen superheater; 25. Final stage superheater; 26. Economizer. 31. First pipeline; 32. Second pipeline; 33. Flue gas bypass; 34. Third manual valve; 35. Third pipeline; 36. Third temperature measurement unit; 4. Flue gas regulating device; 41. First temperature measuring unit; 42. First manual valve; 43. Pressure measuring unit; 44. Electric regulating valve; 45. Flue gas flow meter; 46. Second manual valve. 5. Denitrification reactor; 6. Air preheater; 7. Flue gas cooler. Detailed Implementation

[0018] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0019] The boiler flue heat exchange device of the present invention, according to an embodiment of the present invention, is described below with reference to the accompanying drawings. Figure 1 and Figure 2 As shown, the boiler flue heat exchange device according to an embodiment of the present invention includes a furnace, a flue 1, a heat exchanger, a denitrification reactor 5, and a flue gas conditioning unit.

[0020] Flue 1 includes a first flue section 11, a second flue section 12, and a third flue section 13, with the flue gas outlet of the furnace, the first flue section 11, the second flue section 12, and the third flue section 13 connected sequentially. The first flue section 11 and the third flue section 13 extend vertically, while the second flue section 12 extends horizontally. The first flue section 11 includes a flame deflector section 111, which connects the first flue section 11 and the second flue section 12. The upper middle part of the third flue section 13 is provided with at least one set of flue gas outlets, each set of flue gas outlets including multiple flue gas outlets, at least a portion of which are spaced apart vertically.

[0021] The heat exchanger is located in flue 1, and at least part of the heat exchanger is located in the third flue section 13 and below the flue gas outlet.

[0022] The heat exchanger includes a horizontal low-temperature superheater 21, a vertical low-temperature superheater 22, a partition screen superheater 23, a rear screen superheater 24, a final stage superheater 25, and an economizer 26. The horizontal low-temperature superheater 21, the vertical low-temperature superheater 22, the partition screen superheater 23, the rear screen superheater 24, and the final stage superheater 25 are connected in sequence.

[0023] Both the horizontal low-temperature superheater 21 and the vertical low-temperature superheater 22 are located within the third flue section 13. The vertical low-temperature superheater 22 is positioned above the horizontal low-temperature superheater 21, and its lower inlet is connected to the upper outlet of the horizontal low-temperature superheater 21. The horizontal low-temperature superheater 21 includes multiple heat exchange tube sections spaced apart in the vertical direction and extending horizontally. The vertical low-temperature superheater 22 includes heat exchange tube sections extending in the vertical direction. The partition screen superheater 23 and the rear screen superheater 24 are located within the first flue section 11, with the rear screen superheater 24 located on the side of the partition screen superheater 23 adjacent to the second flue section 12. The final stage superheater 25 is located within the second flue section 12.

[0024] Economizer 26 is located within the third flue section 13, below the horizontal low-temperature superheater 21. The denitrification reactor 5, air preheater 6, and flue gas cooler 7 are connected in sequence.

[0025] The inlet of the denitrification reactor 5 is connected to the outlet at the lower end of the third flue section 13. Specifically, the flue gas discharged from the furnace passes through the partition screen superheater 23, the rear screen superheater 24, the final stage superheater 25, the vertical low-temperature superheater 22, the horizontal low-temperature superheater 21, and the economizer 26 in sequence for heat exchange before entering the denitrification reactor 5 for denitrification. The denitrified flue gas is then cooled sequentially by the air preheater 6 and the flue gas cooler 7 before being discharged.

[0026] The flue gas conditioning unit includes multiple first pipes 31, second pipes 32, and a flue gas conditioning device 4. The inlets of the multiple first pipes 31 are connected to multiple flue gas outlets in a corresponding manner. The outlets of the multiple first pipes 31 are connected to the second pipes 32. The outlet of the second pipes 32 is connected to the inlet of the denitrification reactor 5, so that the flue gas discharged from the second pipes 32 enters the inlet of the denitrification reactor 5. The flue gas conditioning device 4 is used to regulate the flow rate of the flue gas discharged from the second pipes 32.

[0027] Specifically, the flue gas regulating device 4 is used to regulate the flow rate of the flue gas discharged from the second pipeline 32 and ensure that the temperature of the mixed flue gas entering the denitrification reactor 5 is greater than or equal to 300°C. Specifically, the temperature of the flue gas discharged from the flue gas regulating device 4 is greater than the temperature of the flue gas discharged from the third flue section 13. The flue gas discharged from the flue gas regulating device 4 and the flue gas discharged from flue 1 (third flue section 13) are introduced into the denitrification reactor 5 to form a mixed flue gas, and the temperature of the mixed flue gas is much greater than 300°C. For example, the flue gas regulating device 4 is used to regulate the flow rate of the flue gas discharged from the second pipeline 32 and ensure that the temperature of the mixed flue gas entering the denitrification reactor 5 is greater than or equal to 305°C and less than or equal to 315°C.

[0028] In some embodiments, at least a portion of the plurality of flue gas outlets are located between the upper and lower ends of the horizontal low-temperature superheater 21 in the vertical direction, thereby allowing the higher-temperature flue gas in the third flue section 13 located between the upper and lower ends of the horizontal low-temperature superheater 21 in the vertical direction to be introduced into the denitrification reactor 5.

[0029] In some embodiments, at least a portion of the plurality of flue gas outlets are located between the upper and lower ends of the vertical low-temperature superheater 22 in the vertical direction, thereby allowing the higher temperature flue gas in the third flue section 13 located between the upper and lower ends of the vertical low-temperature superheater 22 in the vertical direction to be introduced into the denitrification reactor 5.

[0030] In some embodiments, the plurality of flue gas outlets in each group of flue gas outlets includes a first flue gas outlet 14 and a second flue gas outlet 15, or the plurality of flue gas outlets in each group of flue gas outlets includes a first flue gas outlet 14, a second flue gas outlet 15, and a third flue gas outlet 16. High-temperature flue gas discharged through at least one of the first flue gas outlet 14, the second flue gas outlet 15, and the third flue gas outlet 16 can be introduced into the denitrification reactor 5.

[0031] The first flue gas outlet 14 is located between the upper and lower ends of the vertical low-temperature superheater 22 in the vertical direction, thereby discharging the high-temperature flue gas located between the vertical low-temperature superheaters 22 in the vertical direction. The second flue gas outlet is located in the middle position of the horizontal low-temperature superheater 21 in the vertical direction; the third flue gas outlet is located in the middle position of the horizontal low-temperature superheater 21 in the vertical direction.

[0032] In some embodiments, there are multiple sets of flue gas outlets and multiple flue gas regulating devices 4. The multiple sets of flue gas outlets are connected to the denitrification reactor 5 one-to-one through the multiple flue gas regulating devices 4. Thus, the temperature and flow rate of the flue gas entering the denitrification reactor 5 can be controlled by the multiple sets of flue gas outlets and the multiple flue gas regulating devices 4.

[0033] In some embodiments, the flue gas regulating device 4 includes a first temperature measuring unit 41, a first manual valve 42, a pressure measuring unit 43, an electric regulating valve 44, a flue gas flow meter 45, and a second manual valve 46. The first temperature measuring unit 41, the first manual valve 42, the pressure measuring unit 43, the electric regulating valve 44, the flue gas flow meter 45, and the second manual valve 46 are sequentially arranged on the second pipeline 32 in a direction away from the first pipeline 31.

[0034] In some embodiments, the second pipeline 32 is provided with a flue gas bypass 33 connected thereto. The inlet of the flue gas bypass 33 is located between the first temperature measuring unit 41 and the first manual valve 42 in the extension direction of the second pipeline 32. The outlet of the flue gas bypass 33 is located between the second manual valve 46 and the outlet of the second pipeline 32 in the extension direction of the second pipeline 32. The flue gas bypass 33 is provided with a third manual valve 34.

[0035] Specifically, the first temperature measuring unit 41 measures the flue gas temperature at the inlet of the second pipeline 32 and the flue gas bypass 33. When it is necessary to introduce flue gas at a preset temperature into the denitrification reactor 5, the third manual valve 34 (flue gas bypass 33) can be closed first, and the first manual valve 42, the electric regulating valve 44, and the second manual valve 46 can be opened. The electric regulating valve 44 adjusts the opening of the second pipeline 32, thereby allowing a certain flow rate of flue gas to enter the denitrification reactor 5. The pressure measuring unit 43 measures the pressure between the first manual valve 42 and the second manual valve 46, and the flue gas flow meter 45 measures the flow rate of the second pipeline 32. The measurement data from the flue gas flow meter 45 can facilitate the electric regulating valve 44 in adjusting the flow rate within the second pipeline 32.

[0036] When the electric regulating valve 44 needs to be inspected, the third manual valve 34 (flue gas bypass 33) can be opened first, and then the first manual valve 42 and the second manual valve 46 can be closed so that the flue gas can be introduced into the denitrification reactor 5 through the flue gas bypass 33.

[0037] In some embodiments, the second pipe 32 is connected to the denitrification reactor 5 via a plurality of third pipes 35, the third pipes 35 extending into the denitrification reactor 5, and the plurality of third pipes 35 being spaced apart. The denitrification reactor 5 is provided with a plurality of spaced-apart third temperature measuring units 36. This facilitates the uniform flow of flue gas into the denitrification reactor 5, and the plurality of third temperature measuring units 36 facilitates the detection of temperatures at multiple locations at the inlet of the denitrification reactor 5.

[0038] For example, multiple third pipelines 35 are spaced apart at the inlet of the denitrification reactor 5 in the vertical direction and / or in the width direction of the denitrification reactor 5. Also, for example, the first temperature measuring unit 41 and the third temperature measuring unit 36 ​​are temperature transmitters.

[0039] like Figure 2 As shown, in some embodiments, the first flue section 11 and the third flue section 13 are arranged side by side in the first horizontal direction. There are two sets of flue gas outlets, each located on either side of the third flue section 13 in the second horizontal direction. Any two of the first horizontal direction, the second horizontal direction, and the vertical direction are perpendicular to each other. For example, the first flue section 11 is located in front of the third flue section 13, and the two sets of flue gas outlets are located on either side of the third flue section 13 in the left-right direction.

[0040] In some embodiments, the flue gas outlet is the opening left by removing the steam sootblower at least one of the horizontal low-temperature superheater 21 and the vertical low-temperature superheater 22 in the third flue section 13. Specifically, the present invention mainly utilizes the steam sootblower of the low-temperature superheater (horizontal low-temperature superheater 21 and vertical low-temperature superheater 22) arranged in the vertical flue (third flue section 13) at the tail of the 330MW boiler (HG-1018 / 18.6-PM19). Since the steam sootblower here is prone to leakage of the heating surface of the low-temperature superheater due to soot blowing, it has long been decommissioned, and several plant-use compressed air sonic sootblowers have been added next to the decommissioned sootblower. The specific measure is to remove the upper and lower two of the manhole doors on the outer side of the three steam soot blowers on each side (the upper one is located between the horizontal low-temperature superheater 21 and the vertical low-temperature superheater 22, and the lower two are located in the middle of the horizontal low-temperature superheater 21), thereby forming at least one of the first flue gas outlet 14, the second flue gas outlet 15, and the third flue gas outlet 16.

[0041] Then, a flue gas extraction pipe of appropriate size is installed using the expansion joint of the steam soot blower. For ease of operation and maintenance, a flue gas regulating unit can be installed on the flue gas duct at the platform location where the steam soot blower was removed. Online regulation is achieved via an electric regulating valve 44. Considering that the SCR inlet flue gas temperature may fall below 300℃ at any two points and the low-temperature interlock is activated, the ammonia injection pneumatic quick-closing valve is closed. Therefore, in the operating logic, the SCR denitrification reactor inlet flue gas temperature can be set to operate within a certain range of 305 to 315℃. The flue gas volume is increased or decreased according to actual temperature changes to always ensure that the SCR denitrification reactor inlet flue gas temperature is maintained above 300℃. Simultaneously, some of the high-temperature flue gas at the outlet and middle of the horizontal low-temperature superheater is extracted, which can improve the excessively high steam temperature at the low-temperature superheater outlet under low load conditions and reduce or even avoid overheating of the tube walls of the partition screen superheater and the rear screen superheater. In addition, to reduce the impact of high-temperature flue gas, eliminate temperature stratification, and ensure the uniformity of flue gas temperature at the inlet of the SCR denitrification catalyst, flue gas branch pipes can be uniformly led out from each side flue gas pipe, and radial guide plates are installed in the outlet pipes of the flue gas branch pipes.

[0042] This invention aims to install a flue gas bypass device between the low-temperature superheater and the inlet of the SCR denitrification reactor. This device introduces a portion of the high-temperature flue gas from the outlet and middle of the horizontal low-temperature superheater into the low-temperature flue gas at the inlet of the SCR denitrification reactor. Thus, when the unit is operating at a low load during deep peak shaving, this device can automatically adjust the input of an appropriate amount of higher-temperature flue gas to meet the inlet flue gas temperature requirements of the SCR denitrification reactor. This alleviates superheater tube wall overheating and ensures that the SCR denitrification inlet flue gas temperature is maintained above 300℃. Ultimately, this achieves multiple objectives: reducing the output of the forced and induced draft fans, reducing ammonia injection, ensuring the safety of the heating surfaces, and eliminating potential environmental pollution hazards.

[0043] Therefore, the boiler flue heat exchange device according to the embodiments of the present invention can facilitate the maintenance of flue gas temperature in the denitrification reactor and reduce the amount of ammonia injected.

[0044] This invention also proposes a flue gas modification method. According to an embodiment of the invention, the method includes the following steps: at least partially removing multiple steam soot blowers from at least one of the horizontal low-temperature superheater 21 and the vertical low-temperature superheater 22 on the flue gas 1; using the opening left after removing the steam soot blowers on the flue gas 1 as a flue gas outlet; and connecting the flue gas outlet to the inlet of the denitrification reactor 5 through a flue gas regulating section. The flue gas regulating section is used to regulate the temperature of the flue gas introduced into the denitrification reactor 5. The flue gas regulating section is a boiler flue heat exchange device according to an embodiment of the invention, thereby modifying the flue gas into a boiler flue heat exchange device according to an embodiment of the invention.

[0045] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0046] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0047] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0048] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0049] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0050] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A boiler flue heat exchange device, characterized in that, include: Furnace; The flue includes a first flue section, a second flue section, and a third flue section. The flue gas outlet of the furnace, the first flue section, the second flue section, and the third flue section are connected sequentially. The first flue section and the third flue section extend vertically, and the second flue section extends horizontally. The first flue section includes a flame deflector section, which connects the first flue section and the second flue section. The upper middle part of the third flue section is provided with at least one set of flue gas outlets. Each set of flue gas outlets includes multiple flue gas outlets, and at least a portion of the multiple flue gas outlets are spaced apart vertically. A heat exchanger is disposed in the flue, at least a portion of which is located within the third flue section and below the flue gas outlet. A denitrification reactor, wherein the inlet of the denitrification reactor is connected to the outlet at the lower end of the third flue section; The flue gas regulating unit includes multiple first pipelines, second pipelines, and a flue gas regulating device. The inlets of the multiple first pipelines are connected one-to-one with the multiple flue gas outlets, and the outlets of the multiple first pipelines are connected to the second pipelines. The outlets of the second pipelines are connected to the inlet of the denitrification reactor, so that the flue gas discharged from the second pipelines enters the inlet of the denitrification reactor. The flue gas regulating device is used to regulate the flow rate of the flue gas discharged from the second pipelines.

2. The boiler flue heat exchange device according to claim 1, characterized in that, The heat exchanger includes a horizontal low-temperature superheater and a vertical low-temperature superheater. Both the horizontal and vertical low-temperature superheaters are located within the third flue section. The vertical low-temperature superheater is located above the horizontal low-temperature superheater, and the inlet at the lower end of the vertical low-temperature superheater is connected to the outlet at the upper end of the horizontal low-temperature superheater. The horizontal cryogenic superheater includes multiple heat exchange tube sections that are spaced apart in the vertical direction and extend in the horizontal direction. The vertical cryogenic superheater includes heat exchange tube sections extending in the vertical direction. At least a portion of the plurality of flue gas outlets are located between the upper and lower ends of the horizontal cryogenic superheater in the vertical direction; and / or At least a portion of the plurality of flue gas outlets are located between the upper and lower ends of the vertical cryogenic superheater in the vertical direction.

3. The boiler flue heat exchange device according to claim 2, characterized in that, Each group of flue gas outlets includes a first flue gas outlet and a second flue gas outlet, or each group of flue gas outlets includes a first flue gas outlet, a second flue gas outlet and a third flue gas outlet. The first flue gas outlet is located between the upper and lower ends of the vertical low-temperature superheater in the vertical direction; The second flue gas outlet is located in the middle of the horizontal low-temperature superheater in the vertical direction; The third flue gas outlet is located in the middle of the horizontal low-temperature superheater in the vertical direction.

4. The boiler flue heat exchange device according to claim 3, characterized in that, The heat exchanger also includes a partition screen superheater, a rear screen superheater, a final stage superheater, and an economizer, wherein the horizontal low-temperature superheater, the vertical low-temperature superheater, the partition screen superheater, the rear screen superheater, and the final stage superheater are connected in sequence. The partition screen superheater and the rear screen superheater are located within the first flue section; The final stage superheater is located within the second flue section; The economizer is located within the third flue section and is located below the horizontal low-temperature superheater; The denitrification reactor, air preheater, and flue gas cooler are connected in sequence.

5. The boiler flue heat exchange device according to any one of claims 1-4, characterized in that, The flue gas outlets are in multiple sets, and the flue gas regulating devices are in multiple sets. The multiple sets of flue gas outlets are connected to the denitrification reactor one by one through the multiple flue gas regulating devices.

6. The boiler flue heat exchange device according to claim 5, characterized in that, The flue gas regulating device includes a first temperature measuring unit, a first manual valve, a pressure measuring unit, an electric regulating valve, a flue gas flow meter, and a second manual valve. The first temperature measuring unit, the first manual valve, the pressure measuring unit, the electric regulating valve, the flue gas flow meter, and the second manual valve are sequentially arranged on the second pipeline in a direction away from the first pipeline.

7. The boiler flue heat exchange device according to claim 6, characterized in that, The second pipeline is provided with a flue gas bypass connected to it. The inlet of the flue gas bypass is located between the first temperature measuring unit and the first manual valve in the extension direction of the second pipeline. The outlet of the flue gas bypass is located between the second manual valve and the outlet of the second pipeline in the extension direction of the second pipeline. The flue gas bypass is provided with a third manual valve. The second pipeline is connected to the denitrification reactor through multiple third pipelines. The third pipelines extend into the denitrification reactor and are spaced apart. The denitrification reactor is provided with multiple spaced-apart third temperature measuring units.

8. The boiler flue heat exchange device according to claim 5, characterized in that, The first flue section and the third flue section are arranged side by side in the first horizontal direction; The flue gas outlet is in two sets, and the two sets of flue gas outlets are respectively located on both sides of the third flue section in the second horizontal direction. Any two of the first horizontal direction, the second horizontal direction, and the vertical direction are perpendicular to each other. The flue gas regulating device is used to regulate the flow rate of the flue gas discharged from the second pipeline and to ensure that the temperature of the mixed flue gas introduced into the denitrification reactor is greater than or equal to 300°C.

9. The boiler flue heat exchange device according to claim 2, characterized in that, The flue gas outlet is the opening left by removing the steam soot blower at least one of the parts of the third flue section corresponding to the horizontal low-temperature superheater and the vertical low-temperature superheater. The flue gas regulating device is used to regulate the flow rate of the flue gas discharged from the second pipeline and to ensure that the temperature of the mixed flue gas introduced into the denitrification reactor is greater than or equal to 305°C and less than or equal to 315°C.

10. A method for modifying a flue, characterized in that, The method includes the following steps: removing at least a portion of multiple steam soot blowers at at least one of the horizontal and vertical low-temperature superheaters on the flue; using the opening left by removing the steam soot blowers on the flue as a flue gas outlet; connecting the flue gas outlet to the inlet of the denitrification reactor through the flue gas regulating unit, wherein the flue gas regulating unit is used to regulate the temperature of the flue gas introduced into the denitrification reactor.

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