A CFB boiler system

Abstract

The present invention discloses a CFB boiler system, which belongs to the field of thermal energy engineering technology and includes a CFB boiler, wherein the side wall of the CFB boiler is provided with a primary air inlet, an upper secondary air inlet, and a lower secondary air inlet; an exhaust gas source, wherein the exhaust gas source stores exhaust gas rich in CO2 and free of O2; a primary fan connected to the exhaust gas source and the primary air inlet, and used to transport the exhaust gas flowing from the exhaust gas source to the primary air inlet when the CFB boiler is operating in a first load range; and a secondary fan connected to the exhaust gas source, the upper secondary air inlet, and the lower secondary air inlet. The present invention can improve the reducibility of the dense phase zone of the CFB boiler and inhibit NO x The generation of NOx during the operation of the CFB boiler in the first load range is reduced. x The amount of carbon dioxide emissions from the CFB boiler system is reduced, making it easier for the CFB boiler system to meet emission standards.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal energy engineering, and in particular to a CFB boiler system. Background Art

[0002] Circulating fluidized bed (CFB) boilers are widely used in heating, cogeneration, and power station boilers due to their wide fuel adaptability, high combustion efficiency, large load adjustment, direct desulfurization in the bed, and low NOx emissions.

[0003] At present, the NO x Emission requirements need to meet 50mg / Nm 3 To meet the ultra-low emission standards, in-service CFB boilers have been retrofitted with low-nitrogen combustion to reduce NO x Initial emission, combined with the SNCR denitrification system set at the inlet of the cyclone separator to achieve NO x Ultra-low emissions.

[0004] However, when the CFB boiler is operated at a relatively low load (e.g., 20% to 30% load), the larger furnace air distribution plate area determines that the fluidized air volume at the bottom of the CFB boiler cannot be further reduced during low-load operation, resulting in the coal in the dense phase zone of the CFB boiler being burned in an oxidizing atmosphere, and the NO generated during combustion x More likely to exceed 50mg / Nm 3 Even 100mg / Nm 3 However, at this time, the furnace outlet temperature is generally below 800℃, and the SNCR denitrification system arranged at the inlet of the cyclone separator cannot be put into use because the reaction temperature is lower than the denitrification reaction temperature window, resulting in NO x It is difficult to achieve 50mg / Nm 3 The following ultra-low emission standards. Summary of the Invention

[0005] The purpose of the present invention is to provide a CFB boiler system that can improve the reducibility of the dense phase zone of the CFB boiler and inhibit NO x The generation of NOx during the operation of the CFB boiler in the first load range is reduced. x The amount of carbon dioxide emissions from the CFB boiler system is reduced, making it easier for the CFB boiler system to meet emission standards.

[0006] As conceived above, the technical solution adopted by the present invention is:

[0007] A CFB boiler system, comprising:

[0008] CFB boiler, wherein the side wall of the CFB boiler is provided with a primary air inlet, an upper secondary air inlet and a lower secondary air inlet;

[0009] A waste gas source, wherein the waste gas source stores waste gas rich in CO2 and free of O2;

[0010] a primary fan connected to the exhaust gas source and the primary air inlet, the primary fan being configured to convey exhaust gas flowing from the exhaust gas source to the primary fan to the primary air inlet when the CFB boiler is operating in a first load range, wherein the first load range refers to an operating period when the load of the CFB boiler is 20% to 30% of the full load;

[0011] The secondary fan is connected to the exhaust gas source, the upper secondary air inlet and the lower secondary air inlet, and is used to transport the exhaust gas flowing from the exhaust gas source to the secondary fan to the upper secondary air inlet and the lower secondary air inlet.

[0012] Optionally, it further includes an exhaust gas delivery main pipe, a first exhaust gas delivery branch pipe, and a second exhaust gas delivery branch pipe;

[0013] One end of the first exhaust gas delivery branch pipe is connected to the exhaust gas delivery main pipe, the other end of the first exhaust gas delivery branch pipe is connected to the primary air inlet, and the primary fan is installed on the first exhaust gas delivery branch pipe;

[0014] One end of the second exhaust gas delivery branch pipe is connected to the exhaust gas delivery main pipe, and the other end of the second exhaust gas delivery branch pipe is connected to the upper secondary air inlet and the lower secondary air inlet. The secondary fan is installed on the second exhaust gas delivery branch pipe and is used to transport the exhaust gas flowing to the secondary fan to the upper secondary air inlet and the lower secondary air inlet when the CFB boiler is operating in the first load range.

[0015] Optionally, the secondary fan controls the flow rate of the exhaust gas at the upper secondary air inlet and the lower secondary air inlet to be 35 to 60 m / s.

[0016] Optionally, an air source is further included, which is connected to the secondary fan. The secondary fan is also used to input air into the CFB boiler through the upper secondary air inlet and the lower secondary air inlet when the CFB boiler is operating in a second load range. The second load range operation period refers to an operation period when the load of the CFB boiler is more than 30% of the full load.

[0017] Optionally, it further includes a first electric regulating damper, a second electric regulating damper, a first electric shut-off door, a second electric shut-off door and a third electric shut-off door;

[0018] The first electric regulating damper is installed on the first exhaust gas delivery branch pipe and is used to adjust the amount of exhaust gas in the first exhaust gas delivery branch pipe. The second electric regulating damper is installed on the second exhaust gas delivery branch pipe and is used to adjust the amount of exhaust gas in the second exhaust gas delivery branch pipe. The first electric shut-off door is used to open or close the first exhaust gas delivery branch pipe. The second electric shut-off door is used to open or close the second exhaust gas delivery branch pipe. The third electric shut-off door is used to open or close the exhaust gas delivery main pipe.

[0019] Optionally, it also includes an upper secondary air box and a lower secondary air box, the upper secondary air box is connected to the other end of the second exhaust gas conveying branch pipe and the upper secondary air inlet, and the lower secondary air box is connected to the other end of the second exhaust gas conveying branch pipe and the lower secondary air inlet.

[0020] Optionally, the lower secondary air box is connected to the lower secondary air inlet through a first air duct, and the CFB boiler system also includes a denitrification device, which is connected to the first air duct, and the denitrification device is used to spray a denitrification reducing agent into the CFB boiler through the first air duct and the lower secondary air inlet.

[0021] Optionally, the denitrification device includes a dual-fluid atomizing spray gun, and the distance between the nozzle of the dual-fluid atomizing spray gun and the wall of the CFB boiler is greater than 200 mm.

[0022] Optionally, the upper secondary air box is connected to the upper secondary air inlet through a second air duct, and the CFB boiler system further includes a third electric regulating damper installed on the first air duct and a fourth electric regulating damper installed on the second air duct, the third electric regulating damper is used to adjust the flow rate of exhaust gas in the first air duct, and the fourth electric regulating damper is used to adjust the flow rate of exhaust gas in the second air duct.

[0023] Optionally, a first flow meter is provided on the first exhaust gas delivery branch pipe, and a second flow meter is provided on the second exhaust gas delivery branch pipe.

[0024] The present invention has at least the following beneficial effects:

[0025] In the CFB boiler system provided by the present invention, when the CFB boiler is operating in the first load range, the CO2-rich O2-free exhaust gas in the exhaust gas source flows to the primary air inlet and then enters the fluidized air chamber of the CFB boiler, thereby reducing the oxygen content in the primary air. At the same time, it can also ensure that the volume flow rate of the primary air sent into the CFB boiler by the primary fan remains unchanged, thereby improving the reducibility of the dense phase zone of the CFB boiler and suppressing NO xThe generation of NOx during the operation of the CFB boiler in the first load range is reduced. x The amount of carbon dioxide emissions from the CFB boiler system is reduced, making it easier for the CFB boiler system to meet emission standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 1 is a schematic structural diagram of a CFB boiler system provided by an embodiment of the present invention;

[0027] Figure 2 Schematic diagram of the structure of a partial CFB boiler system provided by an embodiment of the present invention.

[0028] In the picture:

[0029] 1. Exhaust gas source; 2. Primary fan; 3. Secondary fan; 4. Exhaust gas main pipe; 5. First exhaust gas branch pipe; 6. Second exhaust gas branch pipe; 7. Air source; 8. First electric damper; 9. Second electric damper; 10. First electric shut-off door; 11. Second electric shut-off door; 12. Third electric shut-off door; 13. Upper secondary air box; 14. Lower secondary air box; 15. First air duct; 16. Second air duct; 17. Denitrification device; 171. Dual-fluid atomizing spray gun; 18. Third electric damper; 19. Fourth electric damper; 20. First flowmeter; 21. Second flowmeter; 22. Fifth flowmeter; 23. Fourth flowmeter; 24. Third flowmeter; 100. CFB boiler; 1001. Fluidizing air chamber. DETAILED DESCRIPTION

[0030] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved more clearly, the technical solutions of the present invention are further described below with reference to the accompanying drawings and through specific embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the drawings only show portions relevant to the present invention, not all of them.

[0031] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed or detachable connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention.

[0033] This embodiment provides a CFB boiler system capable of suppressing NO during low-load operation of the CFB boiler 100. x The generation of carbon monoxide makes the CFB boiler system meet the emission standards.

[0034] like Figure 1 and Figure 2 As shown, the CFB boiler system includes a CFB boiler 100 , an exhaust gas source 1 , a primary air fan 2 and a secondary air fan 3 .

[0035] The side wall of the CFB boiler 100 is provided with a primary air inlet, an upper secondary air inlet, and a lower secondary air inlet. The primary air inlet, the lower secondary air inlet, and the upper secondary air inlet are arranged in sequence from bottom to top. In addition, the primary air inlet is connected to the fluidized air chamber 1001 of the CFB boiler 100, and the lower secondary air inlet and the upper secondary air inlet are respectively connected to the furnace of the CFB boiler 100.

[0036] The primary fan 2 is connected to the exhaust gas source 1 and the primary air inlet. When the CFB boiler 100 is operating in a first load range, the primary fan 2 is configured to transport the exhaust gas flowing from the exhaust gas source 1 to the primary fan 2 to the primary air inlet. This reduces the oxygen content of the primary air while maintaining the volume flow rate of the primary air delivered by the primary fan 2 to the fluidizing chamber 1001. The first load range refers to the period when the CFB boiler 100 is operating at a load between 20% and 30% of full load, which can also be understood as a low-load operating stage.

[0037] The secondary fan 3 is connected to the exhaust gas source 1, the upper secondary air inlet, and the lower secondary air inlet. The secondary fan 3 is configured to transport the exhaust gas flowing from the exhaust gas source 1 to the secondary fan 3 to the upper secondary air inlet and the lower secondary air inlet during a suitable operating phase. The suitable operating phase may be when the CFB boiler 100 is operating in the first load range.

[0038] In the CFB boiler system provided by this embodiment, when the CFB boiler 100 is operating in the first load range, the CO2-rich O2-free exhaust gas in the exhaust gas source 1 flows to the primary air inlet and then enters the fluidized air chamber 1001 of the CFB boiler 100, thereby reducing the oxygen content in the primary air. At the same time, the volume flow rate of the primary air sent to the CFB boiler 100 by the primary fan 2 is ensured to remain unchanged, thereby improving the reducing performance of the dense phase zone of the CFB boiler 100 and suppressing the formation of NO. x The generation of NOx during the operation of the CFB boiler 100 in the first load range is reduced. x The amount of carbon dioxide emissions from the CFB boiler system is reduced, making it easier for the CFB boiler system to meet emission standards.

[0039] In this embodiment, the waste gas source 1 stores waste gas rich in CO2 and free of O2. For example, the waste gas source 1 in this embodiment can be a low-temperature methanol washing waste gas source, that is, the waste gas obtained in the low-temperature methanol washing process. The waste gas does not contain O2 and is mainly inert gas without corrosive gas components. It will not cause corrosion of the circulation pipeline equipment and the low-temperature end of the CFB boiler, thereby extending the service life of the CFB boiler system.

[0040] Furthermore, the residual pressure of the CO2-rich, O2-free exhaust gas after the low-temperature methanol washing process is relatively high, generally exceeding 0.1 MPa. Therefore, the residual pressure of the exhaust gas can be fully utilized based on the resistance of the exhaust gas pipeline. For example, when the residual pressure of the exhaust gas within the exhaust gas source 1 is higher than 15 kPa, the exhaust gas can be directly delivered from the exhaust gas source 1 to the outlets of the primary fan 2 and the secondary fan 3. The exhaust gas then enters the subsequent air ducts, fully utilizing the residual pressure of the exhaust gas. There is no need to install an additional booster fan, which eliminates the need for additional power consumption for the CFB boiler system. When the exhaust gas pressure is lower than 15 kPa, the residual pressure of the exhaust gas can deliver the exhaust gas to the inlets of the primary fan 2 and the secondary fan 3, respectively. Because the inlets of the primary fan 2 and the secondary fan 3 are in a negative pressure state, the exhaust gas is automatically drawn into the primary fan 2 at the inlet of the primary fan 2 and the secondary fan 3 at the inlet of the secondary fan 3. There is no need to install an additional booster fan, which eliminates the need for additional power consumption for the CFB boiler system.

[0041] Alternatively, as Figure 2 As shown, the CFB boiler system also includes an exhaust gas main pipe 4, a first exhaust gas branch pipe 5, and a second exhaust gas branch pipe 6. One end of the first exhaust gas branch pipe 5 is connected to the exhaust gas main pipe 4, and the other end of the first exhaust gas branch pipe 5 is connected to the primary air inlet. The primary fan 2 is mounted on the first exhaust gas branch pipe 5 and is used to transport the exhaust gas in the first exhaust gas branch pipe 5. In other words, the exhaust gas from the exhaust gas source 1 is transported to the CFB boiler 100 through the exhaust gas main pipe 4 and the first exhaust gas branch pipe 5.

[0042] One end of the second exhaust gas delivery branch pipe 6 is connected to the exhaust gas delivery main pipe 4, and the other end of the second exhaust gas delivery branch pipe 6 is connected to the upper secondary air inlet and the lower secondary air inlet. The secondary fan 3 is installed on the second exhaust gas delivery branch pipe 6 and is used to transport the exhaust gas in the second exhaust gas delivery branch pipe 6 to the upper secondary air inlet and the lower secondary air inlet when the CFB boiler 100 is operating in the first load range.

[0043] During low-load operation of the CFB boiler 100, the dense phase area in the lower part of the furnace is a positive pressure area with a relatively high material concentration. When there is no secondary air or the secondary air volume is very low, the high-temperature material in the furnace flows back to the lower secondary air inlet provided in the dense phase area, which can easily cause the lower secondary air inlet to be burned, carbonized and severely deformed. The lower secondary air inlet needs to be inspected and replaced, and the cost of regular inspection and replacement of the lower secondary air inlet is high. In addition, the rupture of the lower secondary air inlet during operation affects the safe and stable operation of the boiler.

[0044] In response to the above problems, this embodiment introduces exhaust gas into the furnace of the CFB boiler 100 through the secondary fan 3 when the CFB boiler 100 is operating in the first load range. Since the exhaust gas does not contain oxygen, it will not interfere with the low-load operation of the CFB boiler 100. During the low-load operation stage of the CFB boiler 100, a large air volume operation is achieved at the lower secondary air inlet. The high air pressure at the lower secondary air inlet prevents the high-temperature materials in the furnace from flowing back to the lower secondary air inlet. At the same time, a large air volume flows through the lower secondary air inlet, which can achieve cooling of the lower secondary air inlet, thereby solving the burning and deformation problems of the lower secondary air inlet during the low-load operation stage. Since the air sent into the CFB boiler 100 by the secondary fan 3 at this time is all CO2-rich and O2-free exhaust gas after washing with low-temperature methanol, it will not increase the oxygen content in the dense phase area of the CFB boiler 100, thereby further preventing NO x Generation.

[0045] At the same time, during the low-load operation stage, the exhaust gas is fed into the CFB boiler 100 through the secondary fan 3, which can improve the jet rigidity of the lower secondary air (i.e., the exhaust gas) during the low-load operation stage, strengthen the disturbance of the lower secondary air on the materials in the furnace, and increase the upward flow dynamics of the fine-grained materials in the furnace. This is manifested as an increase in the upper furnace differential pressure, and more hot materials enter the upper furnace area, which can further improve the temperature uniformity of the upper and lower furnaces of the CFB boiler 100 during the low-load operation stage, thereby improving the uniformity of combustion.

[0046] For example, in order to ensure the jet rigidity of the exhaust gas, the flow rate of the exhaust gas at the upper secondary air inlet and the lower secondary air inlet is controlled by the secondary fan 3 to be 35-60 m / s.

[0047] In this embodiment, the CFB boiler system may further include an air source 7. The air source 7 is connected to the secondary air fan 3. The secondary air fan 3 is further configured to supply air into the CFB boiler 100 through the upper and lower secondary air inlets when the CFB boiler 100 is operating in a second load range, thereby ensuring sufficient combustion of the fuel in the furnace. This second load range refers to the period when the CFB boiler 100 is operating at a load of at least 30% of full load, which can also be understood as a high-load operating stage.

[0048] Optionally, when the CFB boiler 100 is operating in the second load range, it is necessary to control the primary fan 2 to transport the exhaust gas from the exhaust gas source 1 to the fluidizing air chamber 1001, thereby suppressing NO x Specifically, to ensure normal fuel combustion, the secondary fan delivers air with an oxygen content of 21% to the CFB boiler 100. Exhaust gas is no longer introduced into the furnace through the upper and lower secondary air inlets. Under high load conditions, this can completely replace the conventional flue gas recirculation process of the CFB boiler 100.

[0049] It is understandable that if Figure 1 As shown, the air source 7 is also connected to the primary fan 2. When the CFB boiler 100 is operating in the first load range, the primary fan 2 inlet self-sucks air from the air source 7 and exhaust gas from the exhaust gas source 1 and delivers them to the fluidizing plenum 1001 to maintain stable combustion of the CFB boiler, while the secondary fan 3 self-sucks exhaust gas from the exhaust gas source 1. When the CFB boiler 100 is operating in the second load range, the primary fan 2 inlet self-sucks air from the air source 7 and exhaust gas from the exhaust gas source 1, and the secondary fan 3 inlet self-sucks air from the air source 7.

[0050] like Figure 1 As shown, the CFB boiler system further includes a first electric damper 8 , a second electric damper 9 , a first electric shutoff door 10 , a second electric shutoff door 11 and a third electric shutoff door 12 .

[0051] The first electric damper 8 is mounted on the first exhaust gas branch pipe 5 and is used to adjust the exhaust gas volume in the first exhaust gas branch pipe 5. The second electric damper 9 is mounted on the second exhaust gas branch pipe 6 and is used to adjust the exhaust gas volume in the second exhaust gas branch pipe 6. The first electric shutoff door 10 is mounted on the first exhaust gas branch pipe 5, upstream of the first electric damper 8, and is used to open or close the first exhaust gas branch pipe 5. The second electric shutoff door 11 is mounted on the second exhaust gas branch pipe 6, upstream of the second electric damper 9, and is used to open or close the second exhaust gas branch pipe 6. The third electric shutoff door 12 is mounted on the exhaust gas main pipe 4 and is used to open or close the exhaust gas main pipe 4.

[0052] like Figure 2 As shown, the CFB boiler system also includes an upper secondary air box 13 and a lower secondary air box 14. The upper secondary air box 13 is connected to the other end of the second exhaust gas delivery branch pipe 6 and the upper secondary air inlet. That is, the second exhaust gas delivery branch pipe 6 is connected to the upper secondary air inlet through the upper secondary air box 13. The lower secondary air box 14 is connected to the other end of the second exhaust gas delivery branch pipe 6 and the lower secondary air inlet. That is, the second exhaust gas delivery branch pipe 6 is connected to the lower secondary air inlet through the lower secondary air box 14. The upper secondary air box 13 and the lower secondary air box 14 are used to temporarily store exhaust gas or air. In this embodiment, the upper secondary air box 13 and the lower secondary air box 14 are fixed around the outer wall of the CFB boiler 100.

[0053] Further, if Figure 1 As shown, the lower secondary air blower 14 is connected to the lower secondary air inlet via a first air duct 15. Furthermore, the CFB boiler system further includes a denitrification device 17, which is connected to the first air duct 15 and is configured to inject a denitrification reducing agent into the CFB boiler 100 via the first air duct 15 and the lower secondary air inlet. For example, the denitrification device 17 is supported in the first air duct 15 by a bracket, with the nozzle of the denitrification device 17 positioned adjacent to the lower secondary air inlet.

[0054] In the prior art, the efficiency of the SNCR denitrification system is very low when a denitrification spray gun is simply arranged at the lower secondary air inlet. This is because the lower secondary air inlet is located in the dense phase area of the CFB boiler 100, the material concentration in the furnace is high, and when the secondary air cannot be used during the low-load operation stage, the penetration ability of the atomized reducing agent jet is low.

[0055] In this embodiment, the lower secondary air has high jet and high penetration ability during the low-load operation of the CFB boiler 100. At this time, the reducing agent in the denitrification device 17 penetrates into the furnace with the help of the strong penetration ability of the lower secondary air, thereby enhancing the separation of the reducing agent and the NO in the furnace. x The mixing of NO can further reduce the NOx when the CFB boiler 100 is running at low load. x The specific principle is: First, when the CFB boiler 100 is in low-load operation, the temperature field in the furnace at the lower secondary air inlet elevation is between 850 and 950°C, and the injected denitrification reducing agent can react with NO x React to reduce NO xSecondly, on the basis of improving the penetration ability of the lower secondary air jet when the CFB boiler 100 is running at low load, the atomized reducing agent sprayed by the denitrification device 17 can penetrate deep into the furnace with the help of the penetration of the lower secondary air, greatly improving the uniformity of the mixing of the reducing agent and the flue gas in the furnace, thereby greatly improving the denitrification efficiency of SNCR. Combined with the above-mentioned low-load low-oxygen combustion system, the NO x Ultra-low emissions.

[0056] Furthermore, if Figure 2 As shown, the denitrification device 17 includes a dual-fluid atomizing lance 171. This lance uses compressed air for atomization, and the reducing agent is a 5% to 20% concentration of ammonia or urea solution. During installation, ensure that the nozzle of the dual-fluid atomizing lance 171 is at least 200 mm away from the wall of the CFB boiler 100, or at least 200 mm away from the surface of the castable in the furnace. This prevents wear on the nozzle from high-concentration materials in the furnace and increases the service life of the denitrification device 17. Optionally, multiple dual-fluid atomizing lances 171 can be provided to improve the uniformity of the reducing agent sprayed into the furnace.

[0057] In this embodiment, Figure 1 As shown, the upper secondary air blower 13 is connected to the upper secondary air inlet via the second air duct 16. The CFB boiler system also includes a third electric damper 18 installed on the first air duct 15 and a fourth electric damper 19 installed on the second air duct 16. The third electric damper 18 is used to adjust the flow of exhaust gas in the first air duct 15, and the fourth electric damper 19 is used to adjust the flow of exhaust gas in the second air duct 16. By providing the third electric damper 18 and the fourth electric damper 19, when the CFB boiler 100 is operating within the first load range, the openings of the third electric damper 18 and the fourth electric damper 19 can be adjusted so that most of the exhaust gas in the second exhaust gas branch pipe 6 is delivered to the lower secondary air inlet through the first air duct 15, while only a small amount of exhaust gas is delivered to the upper secondary air inlet through the second air duct 16, thereby increasing the jet rigidity of the exhaust gas at the lower secondary air inlet.

[0058] In this embodiment, a first flowmeter 20 and a third flowmeter 24 are provided on the first exhaust gas delivery branch pipe 5, wherein the first flowmeter 20 is located upstream of the primary fan 2, and the third flowmeter 24 is located downstream of the primary fan 2. A second flowmeter 21 is provided on the second exhaust gas delivery branch pipe 6, wherein the second flowmeter 21 is located upstream of the secondary fan 3. A fourth flowmeter 23 is provided on the first air duct 15, and is located upstream of the third electric damper 18. A fifth flowmeter 22 is provided on the second air duct 16, and is located upstream of the fourth electric damper 19. The first flowmeter 20, the third flowmeter 24, the second flowmeter 21, the fourth flowmeter 23, and the fifth flowmeter 22 are all used to detect flow rates.

[0059] The above embodiments merely illustrate the basic principles and features of the present invention. The present invention is not limited to the above embodiments. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A CFB boiler system, characterized in that: include: CFB boiler, wherein the side wall of the CFB boiler is provided with a primary air inlet, an upper secondary air inlet and a lower secondary air inlet; A waste gas source (1), wherein the waste gas source (1) is a low-temperature methanol-washed waste gas source; a primary fan (2) connected to the exhaust gas source (1) and the primary air inlet, the primary fan (2) being used to transport the exhaust gas flowing from the exhaust gas source (1) to the primary fan (2) to the primary air inlet when the CFB boiler is operating in a first load range, wherein the first load range operation period refers to an operation period when the load of the CFB boiler is 20% to 30% of the full load; a secondary fan (3) connected to the exhaust gas source (1), the upper secondary air inlet, and the lower secondary air inlet, the secondary fan (3) being used to transport the exhaust gas flowing from the exhaust gas source (1) to the secondary fan (3) to the upper secondary air inlet and the lower secondary air inlet; The air source (7) is connected to the primary fan (2) and the secondary fan (3) respectively. When the CFB boiler (100) is operating in a first load range, the primary fan (2) self-sucks the air in the air source (7) and the exhaust gas in the exhaust gas source (1), and the secondary fan (3) self-sucks the exhaust gas in the exhaust gas source (1); when the CFB boiler (100) is operating in a second load range, the primary fan (2) self-sucks the air in the air source (7) and the exhaust gas in the exhaust gas source (1), and the secondary fan (3) self-sucks the air in the air source (7). The second load range operation period refers to the operation period when the load of the CFB boiler is more than 30% of the full load.

2. The CFB boiler system according to claim 1, characterized in that: It also includes an exhaust gas delivery main pipe (4), a first exhaust gas delivery branch pipe (5) and a second exhaust gas delivery branch pipe (6); One end of the first exhaust gas delivery branch pipe (5) is connected to the exhaust gas delivery main pipe (4), the other end of the first exhaust gas delivery branch pipe (5) is connected to the primary air inlet, and the primary fan (2) is installed on the first exhaust gas delivery branch pipe (5); One end of the second exhaust gas delivery branch pipe (6) is connected to the exhaust gas delivery main pipe (4), and the other end of the second exhaust gas delivery branch pipe (6) is connected to the upper secondary air inlet and the lower secondary air inlet. The secondary air fan (3) is installed on the second exhaust gas delivery branch pipe (6) and is used to transport the exhaust gas downstream of the secondary air fan (3) to the upper secondary air inlet and the lower secondary air inlet when the CFB boiler is operating in the first load range.

3. The CFB boiler system according to claim 2, characterized in that: The secondary air blower (3) controls the flow rate of the exhaust gas at the upper secondary air inlet and the lower secondary air inlet to be 35-60 m / s.

4. The CFB boiler system according to claim 2, characterized in that: It also includes a first electric damper (8), a second electric damper (9), a first electric shutoff door (10), a second electric shutoff door (11) and a third electric shutoff door (12); The first electric regulating damper (8) is installed on the first exhaust gas delivery branch pipe (5) and is used to adjust the exhaust gas volume in the first exhaust gas delivery branch pipe (5); the second electric regulating damper (9) is installed on the second exhaust gas delivery branch pipe (6) and is used to adjust the exhaust gas volume in the second exhaust gas delivery branch pipe (6); the first electric shut-off door (10) is used to open or close the first exhaust gas delivery branch pipe (5); the second electric shut-off door (11) is used to open or close the second exhaust gas delivery branch pipe (6); and the third electric shut-off door (12) is used to open or close the exhaust gas delivery main pipe (4).

5. The CFB boiler system according to claim 4, characterized in that: It also includes an upper secondary air box (13) and a lower secondary air box (14), wherein the upper secondary air box (13) is connected to the other end of the second exhaust gas delivery branch pipe (6) and the upper secondary air inlet, and the lower secondary air box (14) is connected to the other end of the second exhaust gas delivery branch pipe (6) and the lower secondary air inlet.

6. The CFB boiler system according to claim 5, characterized in that: The lower secondary air box (14) is connected to the lower secondary air inlet via a first air duct (15). The CFB boiler system further comprises a denitration device (17). The denitration device (17) is connected to the first air duct (15), and the denitration device (17) is used to inject a denitration reducing agent into the CFB boiler via the first air duct (15) and the lower secondary air inlet.

7. The CFB boiler system according to claim 6, characterized in that: The denitrification device (17) includes a dual-fluid atomizing spray gun (171), and the distance between the nozzle of the dual-fluid atomizing spray gun (171) and the wall of the CFB boiler is greater than 200 mm.

8. The CFB boiler system according to claim 6, characterized in that: The upper secondary air box (13) is connected to the upper secondary air inlet through a second air duct (16). The CFB boiler system further includes a third electric damper (18) installed on the first air duct (15) and a fourth electric damper (19) installed on the second air duct (16). The third electric damper (18) is used to adjust the flow rate of exhaust gas in the first air duct (15), and the fourth electric damper (19) is used to adjust the flow rate of exhaust gas in the second air duct (16).

9. The CFB boiler system according to claim 5, characterized in that: The first exhaust gas delivery branch pipe (5) is provided with a first flow meter (20), and the second exhaust gas delivery branch pipe (6) is provided with a second flow meter (21).

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