Flue gas denitrification device with temperature adjustment function

Abstract

The present invention relates to a flue gas denitrification device with a temperature regulating function, comprising: a denitrification reactor, a flue gas duct, an exhaust duct, a waste heat recovery unit, a urea solution adding unit, a reflux duct, and a driver. The exhaust duct is connected to the outlet end of the denitrification reactor; the outlet end of the exhaust duct is provided with an exhaust branch and a recovery branch; the waste heat recovery unit is connected between the denitrification reactor and the exhaust duct; the inlet end of the reflux duct is connected to the recovery branch of the exhaust duct; the outlet end of the reflux duct is connected to the flue gas duct. The flue gas denitrification device with a temperature regulating function reduces the temperature of the flue gas to below 450°C before entering the denitrification reactor by mixing the refluxed clean flue gas, the non-denitrified flue gas, and the urea solution, so that the flue gas can be suitable for a medium-temperature vanadium-based catalyst, thereby reducing the operation and maintenance cost, reducing the temperature of the clean flue gas discharged from the denitrification reactor, recovering the heat energy in the flue gas, and reducing energy loss.

Description

Technical Field

[0001] The invention relates to the technical field of flue gas treatment equipment, and in particular to a flue gas denitrification device with a temperature regulating function. Background Art

[0002] At present, there are generally three types of denitrification catalysts used in flue gas denitrification systems:

[0003] The first type is a low-temperature copper-based catalyst. The operating temperature range of the copper-based catalyst is 170°C to 300°C, and the catalyst cost is relatively high.

[0004] The second type is a medium-temperature vanadium-based catalyst. The operating temperature range of the vanadium-based catalyst is 260°C to 450°C, and the catalyst cost is relatively low.

[0005] The third type is a high-temperature iron-based catalyst. The operating temperature range of the iron-based catalyst is 350°C to 650°C, and the catalyst cost is expensive.

[0006] At present, the outlet flue gas temperature of most internal combustion units running at full load below 2MW or internal combustion units running at partial load above 2MW exceeds 450℃. When the temperature is higher than 450℃, the activity of vanadium-based catalysts is easily lost, resulting in a decrease in the service life of the catalyst. However, the cost of using high-temperature iron-based catalysts is very expensive, and the total sulfur content of most fuel gases is high and is not suitable for copper-based catalysts and iron-based catalysts. Copper-based catalysts and iron-based catalysts easily lose their catalytic activity and reduce their service life. The catalysts need to be replaced frequently, and the operation and maintenance costs are high. Summary of the invention

[0007] Based on this, the present invention provides a flue gas denitration device with a temperature adjustment function, which recovers waste heat and cools the clean flue gas after denitration, and then returns part of the clean flue gas to the flue gas pipeline to mix with the non-denitrated flue gas, thereby adjusting the temperature of the flue gas, so that the temperature of the flue gas is reduced to 450°C before entering the denitration reactor, so that the flue gas can be suitable for medium-temperature vanadium-based catalysts, thereby reducing operation and maintenance costs. Moreover, it can not only reduce the temperature of the clean flue gas discharged from the denitration reactor, but also recover the heat energy in the flue gas, reducing energy loss.

[0008] A flue gas denitrification device with a temperature adjustment function, comprising:

[0009] Denitrification reactor;

[0010] A flue gas duct connected to the denitration reactor; the flue gas duct is connected to the inlet end of the denitration reactor;

[0011] An exhaust pipe connected to the denitration reactor; the exhaust pipe is connected to the outlet end of the denitration reactor; an exhaust branch and a recovery branch are provided at the outlet end of the exhaust pipe;

[0012] A waste heat recovery unit connected between the denitration reactor and the exhaust pipe; the inlet end of the waste heat recovery unit is connected to the outlet end of the denitration reactor, and the outlet end of the waste heat recovery unit is connected to the inlet end of the exhaust pipe;

[0013] A urea solution adding unit connected to the flue gas duct; the urea solution adding unit is used to provide the flue gas in the flue gas duct with urea solution required for catalytic reduction;

[0014] A return duct connected between the flue gas duct and the exhaust duct; the inlet end of the return duct is connected to the recovery branch of the exhaust duct; the outlet end of the return duct is connected to the flue gas duct; and

[0015] A driver connected to the return duct; the driver is used to pump the flue gas in the return duct from the recovery branch of the exhaust duct to the flue gas duct.

[0016] In the flue gas denitrification device with temperature regulating function, the clean flue gas after denitrification treatment in the denitrification reactor first passes through the waste heat recovery unit for waste heat recovery and cooling, and then a part of the clean flue gas is discharged into the atmosphere through the exhaust branch of the exhaust pipe, while the other part of the clean flue gas is led to the inlet end of the return pipe through the recovery branch of the exhaust pipe. Under the action of the driver, this part of the clean flue gas is pushed to the outlet end of the return pipe and enters the flue gas pipe to mix with the flue gas before denitrification, and the urea solution adding unit adds the urea solution required for the denitrification reaction to the flue gas before denitrification. Finally, the non-denitrified flue gas received by the flue gas pipe, the refluxed clean flue gas, and the urea solution are mixed and enter the denitrification reactor together for denitrification treatment. In this process, since the refluxed clean flue gas has been cooled by the waste heat recovery unit, when the refluxed clean flue gas and the urea solution are mixed, the temperature of the mixed flue gas will be lower than the temperature of the non-denitrified flue gas that has just entered the flue gas pipeline, so that the temperature of the flue gas is reduced to below 450°C before entering the denitrification reactor, making the flue gas suitable for medium-temperature vanadium-based catalysts, thereby reducing operation and maintenance costs. In addition, the waste heat recovery unit can not only reduce the temperature of the clean flue gas discharged from the denitrification reactor, but also recover the heat energy in the flue gas to reduce energy loss.

[0017] In one embodiment, the outlet end of the reflux pipe is connected to the inlet end of the flue gas pipe; the urea solution adding unit is located between the outlet end of the reflux pipe and the inlet end of the denitration reactor. The refluxed clean flue gas is first mixed with the flue gas that has just entered the flue gas pipe, and then mixed with the urea solution of the urea solution adding unit.

[0018] In one of the embodiments, the flue gas denitrification device with temperature adjustment function also includes: a first mixer installed on the flue gas duct; the first mixer is located between the inlet end of the reflux duct and the urea solution adding unit; the first mixer is used to fully mix the refluxed flue gas in the reflux duct with the flue gas entering the inlet end of the flue gas duct.

[0019] In one embodiment, the outlet end of the reflux pipe is located between the urea solution addition unit and the inlet end of the denitration reactor. The flue gas just entering the flue gas pipe is first mixed with the urea solution and then mixed with the refluxed clean flue gas.

[0020] In one embodiment, the flue gas denitrification device with temperature adjustment function also includes: a second mixer installed on the flue gas duct; the second mixer is connected to the urea solution adding unit; the second mixer is used to fully mix the urea solution provided by the urea solution adding unit with the flue gas in the flue gas duct.

[0021] In one embodiment, the flue gas denitrification device with temperature adjustment function also includes: a third mixer installed on the flue gas duct; the third mixer is located at one end of the flue gas duct close to the denitrification reactor; the third mixer is used to fully mix the flue gas and urea solution in the flue gas duct.

[0022] In one embodiment, the third mixer includes: a static mixer or a plurality of static mixers arranged in sequence along the extension direction of the flue gas duct.

[0023] In one embodiment, the third mixer includes: one or more of a perforated plate mixer, a three-way mixer, or a spiral blade mixer disposed in the flue gas duct.

[0024] In one of the embodiments, the urea solution adding unit includes: a urea solution spray gun connected to the flue gas duct; one end of the urea solution spray gun extends into the flue gas duct; a urea solution port and a compressed air port are provided at one end of the urea solution spray gun located outside the flue gas duct; and a urea solution nozzle is provided at one end of the urea solution spray gun extending into the flue gas duct.

[0025] In one embodiment, the drive is a centrifugal fan. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of a flue gas denitration device with a temperature adjustment function according to the first embodiment of the present invention;

[0027] Figure 2 for Figure 1 The schematic diagram of the working principle of the flue gas denitrification device with temperature adjustment function shown;

[0028] Figure 3It is a schematic diagram of a flue gas denitration device with temperature adjustment function according to the second embodiment of the present invention.

[0029] The meanings of the symbols in the accompanying drawings are:

[0030] (100, 100a) - a flue gas denitrification device with a temperature regulating function;

[0031] 10- denitration reactor;

[0032] 20- Flue gas duct;

[0033] 30-exhaust pipe, 31-exhaust branch, 32-recovery branch;

[0034] 40-waste heat recovery unit, 41-diverter pipe;

[0035] 50-urea solution adding unit, 51-urea solution spray gun, 511-urea solution port, 512-compressed air port, 513-urea solution nozzle;

[0036] 60-Return pipe;

[0037] 70-Driver;

[0038] 81 - first mixer, 82 - second mixer, 83 - third mixer, 831 - second static mixer, 832 - third static mixer;

[0039] 91 - pressure sensor, 92 - first nitrogen oxide sensor, 93 - temperature sensor, 94 - second nitrogen oxide sensor;

[0040] 200-Engine. DETAILED DESCRIPTION

[0041] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0042] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0044] A flue gas denitrification device with a temperature adjustment function, comprising:

[0045] Denitrification reactor;

[0046] A flue gas duct connected to the denitration reactor; the flue gas duct is connected to the inlet end of the denitration reactor;

[0047] An exhaust pipe connected to the denitration reactor; the exhaust pipe is connected to the outlet end of the denitration reactor; an exhaust branch and a recovery branch are provided at the outlet end of the exhaust pipe;

[0048] A waste heat recovery unit connected between the denitration reactor and the exhaust pipe; the inlet end of the waste heat recovery unit is connected to the outlet end of the denitration reactor, and the outlet end of the waste heat recovery unit is connected to the inlet end of the exhaust pipe;

[0049] A urea solution adding unit connected to the flue gas duct; the urea solution adding unit is used to provide the flue gas in the flue gas duct with urea solution required for catalytic reduction;

[0050] A return duct connected between the flue gas duct and the exhaust duct; the inlet end of the return duct is connected to the recovery branch of the exhaust duct; the outlet end of the return duct is connected to the flue gas duct; and

[0051] A driver connected to the return duct; the driver is used to pump the flue gas in the return duct from the recovery branch of the exhaust duct to the flue gas duct.

[0052] In the flue gas denitrification device with temperature regulating function, the clean flue gas after denitrification treatment in the denitrification reactor first passes through the waste heat recovery unit for waste heat recovery and cooling, and then a part of the clean flue gas is discharged into the atmosphere through the exhaust branch of the exhaust pipe, while the other part of the clean flue gas is led to the inlet end of the return pipe through the recovery branch of the exhaust pipe. Under the action of the driver, this part of the clean flue gas is pushed to the outlet end of the return pipe and enters the flue gas pipe to mix with the flue gas before denitrification, and the urea solution adding unit adds the urea solution required for the denitrification reaction to the flue gas before denitrification. Finally, the non-denitrified flue gas received by the flue gas pipe, the refluxed clean flue gas, and the urea solution are mixed and enter the denitrification reactor together for denitrification treatment. In this process, since the refluxed clean flue gas has been cooled by the waste heat recovery unit, when the refluxed clean flue gas and the urea solution are mixed, the temperature of the mixed flue gas will be lower than the temperature of the non-denitrified flue gas that has just entered the flue gas pipeline, so that the temperature of the flue gas is reduced to below 450°C before entering the denitrification reactor, making the flue gas suitable for medium-temperature vanadium-based catalysts, thereby reducing operation and maintenance costs. In addition, the waste heat recovery unit can not only reduce the temperature of the clean flue gas discharged from the denitrification reactor, but also recover the heat energy in the flue gas to reduce energy loss.

[0053] Below, combined Figures 1 to 3 , providing three different implementation modes of flue gas denitrification devices with temperature adjustment function.

[0054] Embodiment 1

[0055] like Figure 1 and Figure 2 As shown, it is a flue gas denitration device 100 with a temperature adjustment function according to the first embodiment of the present invention.

[0056] like Figure 1 As shown, the flue gas denitrification device 100 with temperature adjustment function includes: a denitrification reactor 10, a flue gas duct 20 connected to the inlet end of the denitrification reactor 10, an exhaust duct 30 connected to the outlet end of the denitrification reactor 10, a waste heat recovery unit 40 connected between the outlet end of the denitrification reactor 10 and the inlet end of the exhaust duct 30, a urea solution adding unit 50 connected to the flue gas duct 20, a reflux duct 60 connected between the flue gas duct 20 and the exhaust duct 30, and a driver 70 connected to the reflux duct 60.

[0057] Among them, an exhaust branch 31 and a recovery branch are provided at the outlet end of the exhaust pipe 30. The inlet end of the waste heat recovery unit 40 is connected to the outlet end of the denitration reactor 10, and the outlet end of the waste heat recovery unit 40 is connected to the inlet end of the exhaust pipe 30. The urea solution adding unit 50 is used to provide the urea solution required for catalytic reduction for the flue gas in the flue gas pipe 20. The inlet end of the reflux pipe 60 is connected to the recovery branch of the exhaust pipe 30. The outlet end of the reflux pipe 60 is connected to the inlet end of the flue gas pipe 20, and the urea solution adding unit 50 is located between the outlet end of the reflux pipe 60 and the inlet end of the denitration reactor 10. The driver 70 is used to pump the flue gas in the reflux pipe 60 from the recovery branch of the exhaust pipe 30 to the inlet end of the flue gas pipe 20.

[0058] like Figure 2 As shown, the clean flue gas after denitration treatment in the denitration reactor 10 first passes through the waste heat recovery unit 40 for waste heat recovery and cooling, and then a part of the clean flue gas is discharged into the atmosphere through the exhaust branch 31 of the exhaust pipe 30, while the other part of the clean flue gas is led to the inlet end of the return pipe 60 through the recovery branch of the exhaust pipe 30. Under the action of the driver 70, the clean flue gas of this part is pushed to the outlet end of the return pipe 60 and enters the inlet end of the flue gas pipe 20 to mix with the flue gas before denitration discharged by the engine 200, and then the urea solution required for the denitration reaction is added through the urea solution adding unit 50. Finally, the non-denitration flue gas received by the flue gas pipe 20, the refluxed clean flue gas, and the urea solution are mixed and enter the denitration reactor 10 together for denitration treatment.

[0059] like Figure 1 As shown, in this embodiment, the flue gas denitration device 100 with a temperature adjustment function further includes: a first mixer 81 installed on the flue gas duct 20. The first mixer 81 is located between the inlet end of the reflux duct 60 and the urea solution adding unit 50. The first mixer 81 is used to fully mix the refluxed flue gas in the reflux duct 60 with the flue gas entering the inlet end of the flue gas duct 20. After the two flue gases are mixed, urea solution is added through the urea solution adding unit 50.

[0060] Furthermore, in this embodiment, the first mixer 81 may be a static mixer (e.g. Figure 1 In other embodiments, the first mixer 81 may also be one or more of a perforated plate mixer, a three-way mixer, or a spiral blade mixer disposed in the flue gas duct 20.

[0061] Similarly, in order to allow the urea solution to be fully mixed with the flue gas when it is added, in this embodiment, Figure 1As shown, the flue gas denitrification device 100 with temperature adjustment function further includes: a second mixer 82 installed on the flue gas duct 20. The second mixer 82 is connected to the urea solution adding unit 50. The second mixer 82 is used to fully mix the urea solution provided by the urea solution adding unit 50 with the flue gas in the flue gas duct 20.

[0062] Further, the second mixer 82 may be a feed mixer.

[0063] In addition, after the urea solution and the clean flue gas are added, before the mixed flue gas enters the denitration reactor 10, in order to allow the three substances to be fully mixed and pyrolyzed and cooled, in this embodiment, Figure 1 As shown, the flue gas denitration device 100 with temperature adjustment function may further include: a third mixer 83 installed on the flue gas duct 20. The third mixer 83 is located at one end of the flue gas duct 20 close to the denitration reactor 10. The third mixer 83 is used to fully mix the flue gas and urea solution in the flue gas duct 20.

[0064] Furthermore, the third mixer 83 may include: a static mixer or a plurality of static mixers arranged in sequence along the extension direction of the flue gas duct 20. Figure 1 As shown, in this embodiment, the third mixer 83 includes: a second static mixer 831 and a third static mixer 832 arranged in sequence along the extension direction of the flue gas duct 20. In other embodiments, the third mixer 83 may include: one or more of a perforated plate mixer, a three-way mixer, or a spiral blade mixer arranged in the flue gas duct 20.

[0065] like Figure 1 As shown, in this embodiment, the urea solution adding unit 50 includes: a urea solution spray gun 51 connected to the flue gas duct 20. One end of the urea solution spray gun 51 extends into the flue gas duct 20. The end of the urea solution spray gun 51 located outside the flue gas duct 20 is provided with a urea solution port 511 and a compressed air port 512. The end of the urea solution spray gun 51 extending into the flue gas duct 20 is provided with a urea solution nozzle 513.

[0066] In this embodiment, the driver 70 is a centrifugal fan. Considering that the temperature of the flue gas is higher than that of the atmospheric environment, a high temperature resistant centrifugal fan can be selected. In other embodiments, other driving mechanisms that can guide the flow of gas can also be used. In addition, according to the change in the discharge volume of the flue gas, a variable frequency centrifugal fan can also be used.

[0067] In this embodiment, the waste heat recovery unit 40 is a waste heat boiler, which can heat water to generate steam or hot water (the flue gas temperature is reduced to 160°C or lower) by heat exchange with the clean flue gas after denitration, and then transport the clean flue gas after cooling to the exhaust pipe 30. In addition, in this embodiment, considering that the processing capacity of the waste heat recovery unit 40 may not be able to cope with the amount of clean flue gas discharged from the denitration reactor 10, in this embodiment, the waste heat recovery unit 40 is also provided with a shunt pipe 41, which can directly guide the clean flue gas discharged from the denitration reactor 10 to the exhaust pipe 30 (a flow regulating valve can also be provided in the shunt pipe 41).

[0068] In other embodiments, the waste heat recovery unit 40 may also be other types of heat exchangers.

[0069] In addition, considering the safety of equipment operation and realizing real-time adjustment of feed amount (refluxed clean flue gas and urea solution), the following sensors can be set as required.

[0070] The pressure sensor 91 connected to the inlet end of the flue gas duct 20 is used to monitor the air pressure at the inlet of the flue gas duct 20 to improve the safety of equipment operation.

[0071] The first nitrogen oxide sensor 92 connected to the flue gas duct 20 is used to monitor the concentration of nitrogen oxides in the flue gas input into the flue gas duct 20, and can be connected to the urea solution adding unit 50 to achieve real-time and automatic adjustment of the input amount of urea solution.

[0072] The temperature sensor 93 connected to the inlet end of the denitration reactor 10 is used to monitor the temperature of the flue gas after cooling, and can be connected to the water adding unit to achieve real-time and automatic adjustment of the input amount of the refluxed flue gas.

[0073] The second nitrogen oxide sensor 94 connected to the outlet end of the denitrification reactor 10 is used to monitor the concentration of nitrogen oxides in the flue gas after denitrification, so as to facilitate the staff to monitor the effect of flue gas denitrification.

[0074] In the flue gas denitration device 100 with a temperature regulating function, the clean flue gas after denitration treatment in the denitration reactor 10 first passes through the waste heat recovery unit 40 for waste heat recovery and cooling, and then a part of the clean flue gas is discharged into the atmosphere through the exhaust branch 31 of the exhaust pipe 30, while the other part of the clean flue gas is led to the inlet end of the return pipe 60 through the recovery branch of the exhaust pipe 30. Under the action of the driver 70, the clean flue gas of this part is pushed to the outlet end of the return pipe 60 and enters the flue gas pipe 20 to mix with the flue gas before denitration, and the urea solution adding unit 50 adds the urea solution required for the denitration reaction to the flue gas before denitration. Finally, the flue gas received by the flue gas pipe 20, the refluxed clean flue gas, and the urea solution are mixed and enter the denitration reactor 10 together for denitration treatment. In this process, since the refluxed clean flue gas has been cooled by the waste heat recovery unit 40, when the refluxed clean flue gas and the urea solution are mixed, the temperature of the mixed flue gas will be lower than the temperature of the non-denitrified flue gas that has just entered the flue gas duct 20, so that the temperature of the flue gas is reduced to below 450°C before entering the denitrification reactor 10, so that the flue gas can be suitable for medium-temperature vanadium-based catalysts, thereby reducing operation and maintenance costs. In addition, the waste heat recovery unit 40 can not only reduce the temperature of the clean flue gas discharged from the denitrification reactor 10, but also recover the heat energy in the flue gas to reduce energy loss.

[0075] In one embodiment,

[0076] Embodiment 2

[0077] like Figure 3 As shown, it is a flue gas denitration device 100 with a temperature adjustment function according to the second embodiment of the present invention.

[0078] The difference between this embodiment and the first embodiment is that in the flue gas denitration device 100 with temperature adjustment function of this embodiment, the input point of the refluxed flue gas in the flue gas duct 20 is different. In this embodiment, the outlet end of the reflux duct 60 is located between the urea solution addition unit 50 and the inlet end of the denitration reactor 10. The flue gas just entering the flue gas duct 20 is first mixed with the urea solution and then mixed with the refluxed clean flue gas.

[0079] In addition, in this embodiment, the first mixer 81 in the first embodiment can be deleted, and after the reflux clean flue gas is added, it is directly mixed through the subsequent third mixer 83.

[0080] The other structures of this embodiment are the same as those of the first embodiment, and can also achieve the beneficial effects of the first embodiment.

[0081] It is additionally noted that, in other embodiments, it is also possible to consider setting the outlet end of the return pipe 60 and the outlet end of the urea solution addition unit 50 as the same input point of the flue gas duct 20, or connecting the outlet end of the return pipe 60 to the urea solution addition unit 50 and mixing with the urea solution before inputting them together into the flue gas duct 20 (for example, the compressed air, urea solution, and the refluxed clean flue gas are input into the flue gas duct 20 together through the urea solution spray gun 51, or the refluxed clean flue gas is input into the compressed air port 512 as compressed air, and a boosting device such as a boosting pump can be appropriately added according to the pressure requirement, or the output power of the driver 70 can be adjusted).

[0082] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0083] The above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A flue gas denitrification device with a temperature adjustment function, characterized in that: include: Denitrification reactor; A flue gas duct connected to the denitration reactor; the flue gas duct is connected to the inlet end of the denitration reactor; An exhaust pipe connected to the denitration reactor; the exhaust pipe is connected to the outlet end of the denitration reactor; the outlet end of the exhaust pipe is provided with an exhaust branch and a recovery branch; A waste heat recovery unit connected between the denitration reactor and the exhaust pipe; the inlet end of the waste heat recovery unit is connected to the outlet end of the denitration reactor, and the outlet end of the waste heat recovery unit is connected to the inlet end of the exhaust pipe; A urea solution adding unit connected to the flue gas duct; the urea solution adding unit is used to provide the flue gas in the flue gas duct with urea solution required for catalytic reduction; A return pipe connected between the flue gas pipe and the exhaust pipe; the inlet end of the return pipe is connected to the recovery branch of the exhaust pipe; the outlet end of the return pipe is connected to the flue gas pipe; as well as A driver connected to the return duct; the driver is used to pump the flue gas in the return duct from the recovery branch of the exhaust duct to the flue gas duct; The outlet end of the return pipe and the outlet end of the urea solution addition unit are set as the same input point of the flue gas duct, or the outlet end of the return pipe is connected to the urea solution addition unit and mixed with the urea solution before being input into the flue gas duct together; A second mixer is installed on the flue gas duct; the second mixer is connected to the urea solution adding unit, and the second mixer is used to fully mix the urea solution provided by the urea solution adding unit with the flue gas in the flue gas duct.

2. The flue gas denitrification device with temperature adjustment function according to claim 1, characterized in that: The outlet end of the reflux pipe is connected to the inlet end of the flue gas pipe; the urea solution adding unit is located between the outlet end of the reflux pipe and the inlet end of the denitration reactor.

3. The flue gas denitrification device with temperature adjustment function according to claim 2, characterized in that: Also includes: a first mixer installed on the flue gas duct; the first mixer is located between the inlet end of the return duct and the urea solution adding unit; The first mixer is used to fully mix the refluxed flue gas in the reflux duct with the flue gas entering the inlet end of the flue gas duct.

4. The flue gas denitrification device with temperature adjustment function according to claim 1, characterized in that: The outlet end of the reflux pipe is located between the urea solution adding unit and the inlet end of the denitration reactor.

5. The flue gas denitrification device with temperature adjustment function according to claim 1, characterized in that: Also includes: A third mixer is installed on the flue gas duct; the third mixer is located at one end of the flue gas duct close to the denitration reactor; the third mixer is used to fully mix the flue gas and urea solution in the flue gas duct.

6. The flue gas denitrification device with temperature adjustment function according to claim 5, characterized in that: The third mixer includes: a static mixer or a plurality of static mixers arranged in sequence along the extension direction of the flue gas duct.

7. The flue gas denitrification device with temperature adjustment function according to claim 5, characterized in that: The third mixer includes: one or more of a perforated plate mixer, a three-way mixer, or a spiral blade mixer arranged in the flue gas duct.

8. The flue gas denitrification device with temperature adjustment function according to claim 1, characterized in that: The urea solution adding unit includes: a urea solution spray gun connected to the flue gas duct; one end of the urea solution spray gun extends into the flue gas duct; the end of the urea solution spray gun located outside the flue gas duct is provided with a urea solution port and a compressed air port; the end of the urea solution spray gun extending into the flue gas duct is provided with a urea solution nozzle.

9. The flue gas denitrification device with temperature adjustment function according to claim 1, characterized in that: The driver is a centrifugal fan.

Images