System and method for increasing SCR inlet smoke temperature

Abstract

The invention belongs to the field of thermal power plant boilers, and discloses a system and method for increasing the SCR inlet smoke temperature, the system comprises a boiler system and an SCR area, an atomization device used for spraying water mist into a hearth is arranged above an over fire air area on the upper side of the hearth of the boiler system, the SCR area is connected with a tail flue of the boiler system, and the SCR area is connected with the tail flue of the boiler system. And an SCR inlet flue temperature detection device is arranged in front of the inlet of the SCR area. The atomization device is additionally arranged above the over-fire air area on the upper side of the hearth, small-particle-size water mist can be sprayed above flames, the heat exchange intensity of the over-fire area is reduced, meanwhile, the flow speed of smoke can be increased through the steam volume expansion effect, the residence time of the smoke in the tail flue is shortened, the heat transfer efficiency of the heat exchange face is further restrained, and the smoke temperature of the SCR inlet flue is increased.

Description

Technical Field

[0001] The invention belongs to the field of thermal power plant boilers, and in particular relates to a system and method for improving the SCR inlet smoke temperature. Background Art

[0002] As the peak load demand of the power system intensifies, it has become the norm for coal-fired units to frequently operate at 40%-50% of the rated load. Under low-load conditions, the flue gas temperature at the tail of the boiler generally drops below 280°C, which is significantly different from the SCR design operating temperature (310-400°C). The economizer grading modification, flue gas bypass temperature adjustment, and burner swing angle adjustment methods used in the existing technology all have obvious defects: economizer grading requires large-scale heating surface modification, and the project investment is as high as tens of millions of yuan; although the flue gas bypass solution can quickly increase the flue gas temperature, it causes a 10%-15% thermal efficiency loss; the burner adjustment is subject to the boiler hydrodynamic safety limit, and the temperature adjustment range is less than 20°C.

[0003] Traditional temperature control methods are difficult to meet the needs of new power systems for deep peak regulation of coal-fired units in terms of economy, safety and adjustment flexibility. Especially after the large-scale grid connection of new energy, the average daily load rate of coal-fired units has continued to decline. How to achieve precise control of SCR inlet flue gas temperature without affecting boiler efficiency has become a key technical bottleneck restricting the flexible operation of ultra-low emission units. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide a system and method for increasing the SCR inlet flue gas temperature. The present invention can effectively increase the flue gas temperature at the tail flue when the unit is started or when the unit is running at low load, and the modification of the unit is relatively small, thereby achieving the effect of reducing the economic and efficiency costs caused by the modification of the tail heating surface.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A system for increasing the inlet smoke temperature of an SCR comprises a boiler system and an SCR zone. The furnace of the boiler system is provided with an atomizing device for spraying water mist into the furnace above the burnout air zone on the upper side. The SCR zone is connected to the tail flue of the boiler system. An SCR inlet flue temperature detection device is provided in front of the inlet of the SCR zone.

[0006] Preferably, the air inlet of the atomizing device is connected to a compressed air source, and the water inlet of the atomizing device is connected to a water source.

[0007] Preferably, the water outlet of the water source is provided with an atomizing device water pressure detection device, and the compressed air outlet of the compressed air source is provided with a compressed air pressure detection device.

[0008] Preferably, the water inlet of the atomizing device is provided with an atomizing device inlet water inlet regulating valve.

[0009] Preferably, the atomization device is arranged 2 to 3 m above the burnout air zone.

[0010] Preferably, the particle size of the water mist after atomization by the atomizing device is ≤50 μm.

[0011] Preferably, a hydrogen-rich exhaust gas burner is provided in the furnace of the boiler system between the main combustion zone and the burnout air zone on the upper side.

[0012] Preferably, the fuel inlet of the hydrogen-rich waste gas burner is connected to an industrial hydrogen-containing waste gas source.

[0013] Preferably, the fuel inlet of the hydrogen-rich waste gas burner is provided with an industrial hydrogen-containing waste gas outlet regulating valve.

[0014] Preferably, the industrial hydrogen-containing waste outlet of the industrial hydrogen-containing waste gas source is provided with an industrial hydrogen-containing waste gas outlet pressure detection device.

[0015] The present invention further provides a method for increasing the smoke temperature at the SCR inlet, which is performed using the system for increasing the smoke temperature at the SCR inlet as described above. The method comprises: When the boiler is in the start-up stage or the boiler is running at low load, if the detection value of the SCR inlet flue temperature detection device is less than the first preset value, water mist is sprayed into the furnace through the atomization device. After the water mist is sprayed into the furnace, the total coal amount can be increased, thereby increasing the total flue gas flow rate and flue gas flow velocity, thereby increasing the inlet flue gas temperature of the SCR area; When the detection value of the SCR inlet flue temperature detection device is not less than the first preset value or the boiler is in normal load operation, the atomization device is turned off and the spraying of water mist into the furnace is stopped.

[0016] Preferably, a furnace of the boiler system is provided with a hydrogen-rich exhaust gas burner between the main combustion zone and the upper burnout air zone, and the method further comprises: When the boiler is in the start-up stage or the boiler is running at low load, if the detection value of the SCR inlet flue gas temperature detection device is less than the first preset value, the hydrogen-rich exhaust gas is burned by the hydrogen-rich exhaust gas burner to move the flame center upward, thereby increasing the inlet flue gas temperature of the SCR area; When the detection value of the SCR inlet flue temperature detection device is not less than the first preset value or the boiler is in normal load operation, the hydrogen-rich exhaust gas burner is turned off.

[0017] Preferably, the water inlet of the atomizing device is provided with an atomizing device inlet water inlet regulating valve, and the fuel inlet of the hydrogen-rich waste gas burner is provided with an industrial hydrogen-containing waste gas outlet regulating valve; the method further comprises: When the boiler is in the startup stage or the boiler is running at low load, the output ratio of the atomization device and the hydrogen-rich waste gas burner is controlled by adjusting the water inlet regulating valve at the atomization device inlet and the industrial hydrogen-containing waste gas outlet regulating valve at the fuel inlet.

[0018] Preferably, when the detection value of the SCR inlet flue temperature detection device is within the vicinity of the first preset value, the water inlet regulating valve at the atomization device inlet is closed, the opening of the industrial hydrogen-containing waste gas outlet regulating valve is increased, and the output ratio of the hydrogen-rich waste gas burner is increased until the detection value of the SCR inlet flue temperature detection device is stabilized above the first preset value; when the output of the hydrogen-rich waste gas burner is full output, and the detection value of the SCR inlet flue temperature detection device is still less than the first preset value, the water inlet regulating valve at the atomization device inlet is opened and the atomization device is put into operation until the detection value of the SCR inlet flue temperature detection device is higher than the first preset value; When the detection value of the SCR inlet flue temperature detection device is stabilized above the first preset value or the boiler is in normal load operation, the atomization device and the hydrogen-rich exhaust gas burner are turned off.

[0019] The present invention has the following beneficial effects: The system for increasing the inlet smoke temperature of SCR of the present invention can spray small-particle water mist above the flame by adding an atomizing device above the burnout wind zone on the upper side of the furnace, thereby reducing the heat exchange intensity of the burnout zone. At the same time, the steam volume expansion effect can increase the flue gas flow rate, shorten the residence time of the flue gas in the tail flue, further inhibit the heat transfer efficiency of the heat exchange surface, and increase the flue gas temperature of the SCR inlet flue. The system structure for increasing the inlet smoke temperature of SCR of the present invention is relatively simple, and does not require a significant modification of the tail heating surface. It can effectively increase the flue gas temperature of the tail flue when the coal-fired unit is running at low load, so that the SCR device can be put into operation normally, reducing the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the system structure for increasing the SCR inlet smoke temperature in an embodiment of the present invention; Figure 2 A schematic diagram of the logical structure (PID) of a system for increasing the SCR inlet smoke temperature in an embodiment of the present invention; Among them, 1 is the main combustion zone, 2 is the burnout wind zone, 3 is the industrial hydrogen-containing waste gas source, 4 is the hydrogen-rich waste gas burner, 5 is the water tank, 6 is the atomization device, 7 is the compressed air storage tank, 8 is the high-temperature reheater, 9 is the high-temperature superheater, 10 is the low-temperature superheater, 11 is the economizer, 12 is the SCR zone, 16 is the industrial hydrogen-containing waste gas outlet pressure detection device, 17 is the industrial hydrogen-containing waste gas outlet regulating valve, 18 is the atomization device water pressure detection device, 19 is the atomization device inlet water inlet regulating valve, 20 is the compressed air pressure detection device, 21 is the SCR inlet flue temperature detection device, and 22 is the tail flue. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only an embodiment of a part of the present invention, not all embodiments, and is not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concepts disclosed in the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0022] When the flue gas flow rate and flue gas velocity in the boiler are increased, the heat transfer of the heat exchange surface can be significantly reduced, thereby increasing the flue gas temperature in the tail flue. Figure 1 and Figure 2 The system for improving the SCR inlet flue gas temperature in this embodiment includes a boiler system and an SCR zone 12. The furnace of the boiler system is provided with an atomizing device 6 for spraying water mist into the furnace above the burnout air zone 2 on the upper side. The SCR zone 12 is connected to the tail flue 22 of the boiler system. An SCR inlet flue gas temperature detection device 21 is provided in front of the entrance of the SCR zone 12.

[0023] The process of increasing the SCR inlet smoke temperature by using the system for increasing the SCR inlet smoke temperature according to the above embodiment of the present invention is as follows: When the boiler is in the start-up stage or the boiler is running at low load, if the detection value of the SCR inlet flue temperature detection device 21 is less than the first preset value, water mist is sprayed into the furnace through the atomizing device 6. After the water mist is sprayed into the furnace, the evaporation process of the water mist absorbs the sensible heat of the flue gas, reducing the heat exchange intensity at the burnout zone 2. At the same time, the volume expansion effect of water vapor can increase the flue gas flow rate in the boiler, shorten the residence time of the flue gas in the tail flue, and further inhibit the heat transfer efficiency of the heat exchange surface. In addition, the addition of water mist can increase the total coal amount, thereby increasing the total flue gas flow rate and flue gas flow rate, reducing the proportion of heat absorption of each level of heating surface to the total heat capacity of the flue gas, thereby increasing the inlet flue gas temperature of the SCR zone 12; When the detection value of the SCR inlet flue temperature detection device 21 is not less than the first preset value or the boiler is in normal load operation, the atomization device 6 is turned off to stop spraying water mist into the furnace.

[0024] Furthermore, as a preferred embodiment of the present invention, in this embodiment, an atomizing device inlet water inlet regulating valve 19 can also be set at the water inlet of the atomizing device 6. The atomizing device inlet water inlet regulating valve 19 can be used to adjust the atomization amount of the atomizing device 6, which is beneficial to adjust the inlet smoke temperature of the SCR zone 12.

[0025] Furthermore, as a preferred embodiment of the present invention, in this embodiment, the atomizing device 6 is arranged 2 to 3 m above the burnout wind zone 2. This arrangement can spray water mist directly into the high-temperature flue gas area (900-1100°C), so that the sprayed water mist can be fully mixed with the flue gas, and the sensible heat of the flue gas can be reduced by evaporating water mist to absorb heat (each kg of water absorbs about 2.26 MJ of heat), thereby reducing the heat absorption of the tail heating surface and increasing the flue gas temperature in the SCR zone.

[0026] Furthermore, as a preferred embodiment of the present invention, in this embodiment, the particle size of the water mist after atomization by the atomizing device 6 is ≤50 μm, ensuring that the water mist is completely evaporated before entering the heating surface, thereby preventing corrosion of the heating surface.

[0027] As a feasible implementation scheme of the present invention, the air inlet of the atomizing device 6 is connected to a compressed air source, and the water inlet of the atomizing device 6 is connected to a water source. The atomizing device 6 can generate water mist using the compressed air provided by the compressed air source and the water provided by the water source. The atomizing device 6, the compressed air source and the water source constitute an atomizing system. Furthermore, in order to ensure the safe operation of the atomizing system, a water pressure detection device 18 of the atomizing device can be set at the water outlet of the water source, and a compressed air pressure detection device 20 can be set at the compressed air outlet of the compressed air source. Among them, the compressed air source can adopt a compressed air storage tank 7, and the water source can adopt a water tank 5.

[0028] Furthermore, as a preferred embodiment of the present invention, this embodiment further provides a hydrogen-rich waste gas burner 4 in the furnace of the boiler system between the main combustion zone 1 and the upper burnout wind zone 2. This embodiment can utilize the hydrogen-rich waste gas burner 4 to burn the hydrogen-rich waste gas to directly increase the local temperature of the flame, thereby increasing the tail flue temperature.

[0029] The process of increasing the SCR inlet smoke temperature by using the system for increasing the SCR inlet smoke temperature according to the above embodiment of the present invention is as follows: When the boiler is in the start-up stage or the boiler is running at low load, if the detection value of the SCR inlet flue gas temperature detection device 21 is less than the first preset value, the hydrogen-rich exhaust gas is burned by the hydrogen-rich exhaust gas burner 4 to generate local high temperature, so that the flame center moves upward, and the flue gas temperature of the rear heating surface of the boiler system (such as the high-temperature reheater 8, the high-temperature superheater 9, the low-temperature reheater 10, and the economizer 11) is correspondingly increased, thereby increasing the inlet flue gas temperature of the SCR area 12; When the detection value of the SCR inlet flue gas temperature detection device 21 is not less than the first preset value or the boiler is in normal load operation, the hydrogen-rich exhaust gas burner 4 is turned off.

[0030] The temperature corresponding to the first preset value may be set to 310°C.

[0031] Furthermore, as a preferred embodiment of the present invention, in this embodiment, an industrial hydrogen-containing waste gas outlet regulating valve 17 can also be set at the fuel inlet of the hydrogen-rich waste gas burner 4. The industrial hydrogen-containing waste gas outlet regulating valve 17 can be used to adjust the combustion intensity of the hydrogen-rich waste gas burner 4, which is beneficial to adjust the flue gas temperature in the furnace and the inlet flue gas temperature of the SCR zone 12.

[0032] In this embodiment, when the water inlet of the atomizing device 6 is provided with an atomizing device inlet water inlet regulating valve 19, and the fuel inlet of the hydrogen-rich exhaust gas burner 4 is provided with an industrial hydrogen-containing exhaust gas outlet regulating valve 17, the system for increasing the SCR inlet flue gas temperature according to the above embodiment of the present invention is used to increase the SCR inlet flue gas temperature as follows: When the boiler is in the start-up stage or the boiler is running at low load, the output ratio of the atomizing device 6 and the hydrogen-rich waste gas burner 4 is controlled by adjusting the water inlet regulating valve 19 at the atomizing device inlet and the industrial hydrogen-containing waste gas outlet regulating valve 17 at the fuel inlet. The specific control process is as follows: When the detection value of the SCR inlet flue temperature detection device 21 is within the range of the first preset value, the atomizer inlet water inlet regulating valve 19 is closed, the opening of the industrial hydrogen-containing waste gas outlet regulating valve 17 is increased, and the output ratio of the hydrogen-rich waste gas burner 4 is increased until the detection value of the SCR inlet flue temperature detection device 21 is stabilized above the first preset value; when the output of the hydrogen-rich waste gas burner 4 is at full output, and the detection value of the SCR inlet flue temperature detection device 21 is still less than the first preset value, the atomizer inlet water inlet regulating valve 19 is opened and the atomizer 6 is put into operation until the detection value of the SCR inlet flue temperature detection device 21 is higher than the first preset value; When the detection value of the SCR inlet flue gas temperature detection device 21 is stabilized above the first preset value or the boiler is in normal load operation, the atomization device 6 and the hydrogen-rich exhaust gas burner 4 are turned off.

[0033] As a feasible implementation scheme of the present invention, the fuel inlet of the hydrogen-rich waste gas burner 4 is connected to an industrial hydrogen-containing waste gas source 3. The hydrogen-containing waste gas of the industrial hydrogen-containing waste gas source 3 comes from the hydrogen-containing waste gas of the metallurgical industry or the hydrogen-containing waste gas of the factory. Hydrogen has the advantages of low ignition energy and fast combustion speed, which can effectively improve the flame stability and reduce NOx from the source. In addition, by arranging the hydrogen-rich waste gas burner 4 above the main combustion zone 1, a high-temperature combustion zone can be established in the middle of the furnace, thereby increasing the overall temperature of the flue gas.

[0034] Furthermore, as a preferred embodiment of the present invention, in this embodiment, the industrial hydrogen-containing waste outlet of the industrial hydrogen-containing waste gas source 3 is provided with an industrial hydrogen-containing waste gas outlet pressure detection device 16, and the industrial hydrogen-containing waste gas outlet pressure detection device 16 is used to detect the outlet pressure of the industrial hydrogen-containing waste gas source 3 to prevent the pressure from being too low.

[0035] Example refer to Figure 1 and Figure 2 The system for increasing the SCR inlet flue gas temperature includes a boiler system and an SCR zone 12, wherein the furnace of the boiler system has a main combustion zone 1, a burnout air zone 2, a high-temperature reheater 8, a high-temperature superheater 9, a low-temperature superheater 10 and an economizer 11, and the burnout air zone 2 refers to the burnout air zone located on the upper side of the main combustion zone 1. In addition, the present embodiment also includes an industrial waste gas source 3, a hydrogen-rich waste gas burner 4, a water tank 5, an atomization device 6 and a compressed air storage tank 7. Among them, the hydrogen-rich waste gas burner 4 is located between the main combustion zone 1 and the burnout wind zone 2, the atomizing device 6 is located 2 to 3 meters above the burnout wind zone 2, the hydrogen-rich waste gas burner 4 is connected to the industrial waste gas source 3, and the pipeline connecting the hydrogen-rich waste gas burner 4 and the industrial waste gas source 3 is provided with an industrial hydrogen-containing waste gas outlet pressure detection device 16 and an industrial hydrogen-containing waste gas outlet regulating valve 17 in sequence along the flow direction of the hydrogen-rich waste gas. The industrial hydrogen-containing waste gas outlet pressure detection device 16 is used to detect the industrial hydrogen-containing waste gas outlet pressure to prevent the pressure from being too low, and the industrial hydrogen-containing waste gas outlet regulating valve 17 is used to adjust the output ratio of the hydrogen-rich waste gas burner 4. The air inlet of the atomizing device 6 is connected to the compressed air outlet of the compressed air storage tank 7, the air inlet of the atomizing device 6 is provided with an atomizing device compressed air inlet regulating valve, and the water inlet of the atomizing device 6 is connected to the water outlet of the water tank 5. On the pipeline connected to the water tank 5 at the water inlet of the atomizing device 6, an atomizing device water flow detection device 18 and an atomizing device inlet water inlet regulating valve 19 are sequentially provided along the water flow direction. The atomizing device water flow detection device 18 is used to detect the water pressure of the water used, and the atomizing device inlet water inlet regulating valve 19 is used to adjust the output ratio of the atomizing device 4. The outlet of the compressed air storage tank 7 also includes a compressed air pressure detection device 20, and an SCR inlet flue temperature detection device 21 is provided in front of the entrance of the SCR area. The SCR inlet flue temperature detection device 21 is used to detect the flue gas temperature before the SCR flue, and the detection value of the SCR inlet flue temperature detection device 21 is used to adjust the opening of the atomizing device inlet water inlet regulating valve 19 and the industrial hydrogen-containing waste gas outlet regulating valve 17, thereby adjusting the output ratio of the atomizing device 6 and the hydrogen-rich waste gas burner 4.

[0036] When the boiler is in the startup stage or the boiler is running at low load, the method of increasing the SCR inlet smoke temperature by using the system for increasing the SCR inlet smoke temperature as described above in this embodiment includes the following process: During the boiler startup stage or when the boiler is running at low load, if the detection value of the SCR inlet flue temperature detection device 21 is less than 310°C, the industrial hydrogen-containing waste gas outlet regulating valve 17 is opened, and the hydrogen-rich waste gas burner 4 is put into use, and the industrial hydrogen-containing waste gas is introduced for combustion, generating local high temperature, and the flame center moves upward, which correspondingly increases the flue gas temperature of the rear heating surface (high-temperature reheater 8, high-temperature superheater 9, low-temperature reheater 10, economizer 11), thereby increasing the SCR inlet flue temperature.

[0037] And open the compressed air inlet regulating valve of the atomizing device, open the water inlet regulating valve 19 of the atomizing device inlet, so that the fine water mist with a particle size of ≤50μm is evenly sprayed into the furnace. By spraying an appropriate amount of water mist, the evaporation process of the water mist absorbs the sensible heat of the flue gas (2.26MJ of heat absorption per kg of water), reducing the heat exchange intensity of the burnout zone. At the same time, the steam volume expansion effect can increase the flue gas flow rate by 0.5-1.2m / s, shorten the residence time of the flue gas in the tail flue, and further inhibit the heat transfer efficiency of the heat exchange surface. In addition, the addition of water mist will increase the total coal volume, increase the total flue gas flow rate, reduce the proportion of heat absorption of each level of heating surface to the total heat capacity of the flue gas, and thus increase the flue gas temperature at the SCR inlet.

[0038] When the detection value of the SCR inlet flue temperature detection device 21 is higher than 310°C, but hovers around (i.e., the detection value of the SCR inlet flue temperature detection device (21) is within the first preset value neighborhood, the size of the neighborhood depends on the specific situation, and the present invention does not make specific restrictions), close the atomization device inlet water inlet regulating valve 19 to reduce the impact on the boiler efficiency; continue to open the industrial hydrogen-containing waste gas outlet regulating valve 17 to increase the output ratio of the hydrogen-rich waste gas burner 4 until the detection value of the SCR inlet flue temperature detection device 21 is higher than 310°C. When the output of the hydrogen-rich waste gas burner 4 is full, the detection value of the SCR inlet flue temperature detection device 21 is still less than 310°C, then open the atomization device inlet water inlet regulating valve 19, the atomization device compressed air inlet regulating valve, and the atomization device 6 until the detection value of the SCR inlet flue temperature detection device 21 is higher than 310°C. Among them, the water inlet regulating valve 19 at the atomizing device inlet and the industrial hydrogen-containing waste gas outlet regulating valve 17 adjust the output ratio of the hydrogen-rich waste gas burner and the atomizing device as the detection value of the SCR inlet flue temperature detection device 21 flue ...

[0039] In this embodiment, a protection measure is provided, that is, when the detection value of the water pressure detection device 18 of the atomizing device and the detection value of the compressed air pressure detection device 20 fail to meet expectations, the water inlet regulating valve 19 at the atomizing device inlet is closed, and adjustments are made to increase the industrial hydrogen-containing waste gas outlet regulating valve 17 to increase the output ratio of the hydrogen-rich waste gas burner; conversely, when the detection value of the industrial hydrogen-containing waste gas outlet pressure detection device 16 is low and fails to meet the output standard of the hydrogen-rich waste gas burner 4, the industrial hydrogen-containing waste gas outlet regulating valve 17 is closed, and adjustments are made to increase the water inlet regulating valve 19 at the atomizing device inlet to increase the output ratio of the atomizing device.

[0040] When the boiler is running under normal load, the industrial hydrogen-containing waste gas outlet regulating valve 17 and the atomizing device inlet water regulating valve 19 are closed, and the compressed air inlet regulating valve is closed. The boiler is running normally.

[0041] It can be seen that this embodiment not only saves energy but also reduces NOx emissions by adding a hydrogen-rich waste gas burner and an atomizing device and introducing industrial hydrogen-containing waste gas for blending. At the same time, hydrogen blending produces local high temperature, which increases the flue gas temperature of the tail heating surface, and thus increases the flue gas temperature of the SCR inlet flue. By adding an atomizing device, the heat exchange intensity of the burnout zone is reduced by spraying small-particle water mist above the flame. At the same time, the steam volume expansion effect can increase the flue gas flow rate, shorten the residence time of the flue gas in the tail flue, further inhibit the heat transfer efficiency of the heat exchange surface, and increase the flue gas temperature of the SCR inlet flue. Through the coordinated adjustment of these two methods, without making a significant modification to the tail heating surface, the flue gas temperature of the tail flue when the coal-fired unit is running at low load can be effectively increased, so that the SCR device can be put into operation normally.

[0042] This embodiment provides a new type of smoke temperature raising system, which can not only meet the rapid response requirements within a wide load range, but also avoid the safety risks brought by the heating surface modification, while minimizing the loss of boiler thermal efficiency. This has important practical significance for promoting the clean and intelligent transformation of coal-fired units.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A system for increasing the smoke temperature at the SCR inlet, characterized in that: The invention comprises a boiler system and an SCR zone (12); an atomizing device (6) for spraying water mist into the furnace is provided above the burnout air zone (2) on the upper side of the furnace of the boiler system; the SCR zone (12) is connected to the tail flue (22) of the boiler system; and an SCR inlet flue temperature detection device (21) is provided in front of the entrance of the SCR zone (12).

2. A system for increasing the SCR inlet smoke temperature according to claim 1, characterized in that: The water inlet of the atomizing device (6) is provided with an atomizing device inlet water inlet regulating valve (19).

3. A system for increasing the SCR inlet smoke temperature according to claim 1, characterized in that: The atomization device (6) is arranged 2 to 3 m above the burnout air zone (2).

4. A system for increasing the SCR inlet smoke temperature according to claim 1, characterized in that: The particle size of the water mist after atomization by the atomization device (6) is ≤50 μm.

5. A system for increasing the SCR inlet smoke temperature according to any one of claims 1 to 4, characterized in that: A hydrogen-rich waste gas burner (4) is provided in the furnace of the boiler system between a main combustion zone (1) and an upper burnout air zone (2).

6. A system for increasing the SCR inlet smoke temperature according to claim 5, characterized in that: The fuel inlet of the hydrogen-rich waste gas burner (4) is provided with an industrial hydrogen-containing waste gas outlet regulating valve (17).

7. A method for increasing the smoke temperature at the SCR inlet, characterized in that: The method is carried out using the system for increasing the SCR inlet smoke temperature according to any one of claims 1 to 6, and the method comprises: When the boiler is in the start-up stage or the boiler is running at low load, if the detection value of the SCR inlet flue gas temperature detection device (21) is less than a first preset value, water mist is sprayed into the furnace through the atomization device (6). After the water mist is sprayed into the furnace, the total amount of coal can be increased, thereby increasing the total flue gas flow rate and the flue gas flow velocity, thereby increasing the inlet flue gas temperature of the SCR area (12); When the detection value of the SCR inlet flue gas temperature detection device (21) is not less than a first preset value or the boiler is operating at normal load, the atomization device (6) is turned off to stop spraying water mist into the furnace.

8. A method for increasing the SCR inlet smoke temperature according to claim 7, characterized in that: The furnace of the boiler system is provided with a hydrogen-rich waste gas burner (4) between a main combustion zone (1) and an upper burnout air zone (2), and the method further comprises: When the boiler is in the start-up stage or the boiler is running at low load, if the detection value of the SCR inlet flue gas temperature detection device (21) is less than a first preset value, the hydrogen-rich waste gas is burned by the hydrogen-rich waste gas burner (4) to move the flame center upward, thereby increasing the inlet flue gas temperature of the SCR area (12); When the detection value of the SCR inlet flue gas temperature detection device (21) is not less than a first preset value or the boiler is operating at normal load, the hydrogen-rich exhaust gas burner (4) is shut down.

9. A method for increasing the SCR inlet smoke temperature according to claim 8, characterized in that: The water inlet of the atomizing device (6) is provided with an atomizing device inlet water inlet regulating valve (19), and the fuel inlet of the hydrogen-rich waste gas burner (4) is provided with an industrial hydrogen-containing waste gas outlet regulating valve (17); the method further comprises: When the boiler is in the start-up stage or the boiler is running at low load, the output ratio of the atomizing device (6) and the hydrogen-rich waste gas burner (4) is controlled by adjusting the water inlet regulating valve (19) at the atomizing device inlet and the industrial hydrogen-containing waste gas outlet regulating valve (17) provided at the fuel inlet.

10. A method for increasing the SCR inlet smoke temperature according to claim 9, characterized in that: When the detection value of the SCR inlet flue temperature detection device (21) is within the range of the first preset value, the atomizing device inlet water inlet regulating valve (19) is closed, the opening of the industrial hydrogen-containing waste gas outlet regulating valve (17) is increased, and the output ratio of the hydrogen-rich waste gas burner (4) is increased until the detection value of the SCR inlet flue temperature detection device (21) is stabilized above the first preset value; when the output of the hydrogen-rich waste gas burner (4) is at full output and the detection value of the SCR inlet flue temperature detection device (21) is still less than the first preset value, the atomizing device inlet water inlet regulating valve (19) is opened and the atomizing device (6) is put into operation until the detection value of the SCR inlet flue temperature detection device (21) is higher than the first preset value; When the detection value of the SCR inlet flue gas temperature detection device (21) is stable above a first preset value or the boiler is operating at normal load, the atomization device (6) and the hydrogen-rich exhaust gas burner (4) are turned off.

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