An automatic circulating ash cleaning system for a boiler air chamber

Abstract

The present invention discloses an automatic circulating ash cleaning system for a boiler air chamber, which includes a primary air duct. An air chamber is provided at the outlet of the primary air duct. A plurality of ash collecting devices communicating with the inner wall of the lower part of the air chamber are arranged at the front end of the air chamber. The primary air duct and the ash collecting devices are connected through loosening air pipes. A furnace is connected above the air chamber. A air distribution plate and air caps are arranged between the furnace and the air chamber. The front part of the furnace is connected with the ash collecting devices through ash conveying pipelines. A separation device is connected to one side of the upper outlet of the furnace. A return device is provided at the lower discharge port of the separation device. The return device is connected to the lower part of the furnace. The present invention realizes the removal of the leaked ash in the air chamber without shutting down the boiler, and at the same time realizes the closed-loop recycling of energy, which is both safe and energy-saving and environment-friendly, and meets the requirements of the long-term stable operation of the circulating fluidized bed boiler.

Description

Technical Field

[0001] The invention belongs to the field of boiler soot cleaning, and particularly relates to an automatic circulating soot cleaning system for a boiler air chamber. Background Art

[0002] Circulating fluidized bed boiler technology is a highly efficient and low-pollution clean combustion technology that has developed rapidly in the past decade or so and has been widely used in power station boilers, industrial boilers, waste treatment and utilization, etc. However, during the operation of circulating fluidized bed boilers, due to reasons such as the wear of air caps on the air distribution plate, the flutter of primary fans, and the bed layer fluctuations caused by the pulsation of circulating materials, a large amount of fine ash often leaks from the air distribution plate into the air chamber. The ash leakage in the air chamber cannot be automatically removed and accumulates more and more, affecting the fluidization of the air distribution plate. Poor bed layer fluidization will cause problems such as incomplete combustion and bed layer coking, and it is necessary to stop the furnace for manual soot cleaning. Manual soot cleaning has a high labor intensity. Later, a soot cleaning device for the air chamber of circulating fluidized bed boilers appeared;

[0003] For example, a soot discharging device for the water-cooled air chamber of a circulating fluidized bed boiler in a thermal power plant disclosed in Chinese Patent CN210107381U controls the current air chamber soot discharging through a new type of valve during furnace shutdown, solving the problems of manual soot cleaning during furnace shutdown, low production efficiency, and high labor intensity of workers, but it fails to achieve on-line automatic soot cleaning of the air chamber, and the continuous operation of the boiler cannot be guaranteed;

[0004] For example, the circulating fluidized bed boiler air chamber slag discharging system disclosed in Chinese Patent CN202392789U sets a plurality of slag discharging ports at the bottom of the air chamber, and a control valve is set on the slag discharging pipe. According to the change of the air chamber temperature, automatic slag discharging of the air chamber is carried out, realizing on-line automatic soot cleaning of the air chamber without stopping the furnace. However, the ash discharging effect is average, and a large amount of fine ash cannot be discharged in time during operation. If the number of air chamber ash discharging ports is increased or the diameter is enlarged, it will affect the fluidization of the air distribution plate. At the same time, the primary hot air at 200 - 300 °C is ejected with the ash, causing energy loss and environmental pollution, and there are also certain safety hazards. Summary of the Invention

[0005] To solve the above problems, the invention provides an automatic circulating soot cleaning system for a boiler air chamber, which realizes the removal of the ash leakage in the air chamber of the boiler without stopping the furnace, and at the same time realizes the closed-loop recycling of energy, which is safe, energy-saving and environment-friendly, and meets the requirements of the long-term stable operation of circulating fluidized bed boilers.

[0006] The technical solution provided by the invention is as follows:

[0007] An automatic circulating ash cleaning system for a boiler wind chamber, comprising a primary air duct. A wind chamber is provided at the outlet of the primary air duct. A plurality of ash collecting devices communicating with the inner wall of the lower part of the wind chamber are arranged at the front end of the wind chamber. The primary air duct and the ash collecting devices are communicated through loosening air ducts. A furnace is connected above the wind chamber. A wind distribution plate and wind caps are arranged between the furnace and the wind chamber. The front part of the furnace is communicated with the ash collecting devices through an ash conveying pipeline. A separation device is connected to one side of the upper outlet of the furnace. A return device is provided at the lower discharge port of the separation device. The return device is connected to the lower part of the furnace.

[0008] Further, the ash collecting device includes a loosening wind chamber arranged at the bottom of the ash collecting device. Loosening wind caps and ash conveying wind caps are arranged on the upper side of the loosening wind chamber. A ash discharge pipe is further provided at the bottom of the ash collecting device.

[0009] Further, one end of the air inlet of the loosening air duct is connected to the primary air duct, and the other end is connected to the loosening wind chamber. The primary air blown out from the primary air duct sequentially passes through the stop valve, electric stop valve and pressure transmitter on the loosening air duct and enters the loosening wind chamber.

[0010] Further, the inlet height H1 of the ash collecting device is 100 - 300 mm, the ash collecting height H2 in the ash collecting device is greater than or equal to 1000 mm, the air volume entering the loosening wind chamber from the loosening air duct is 3 - 5% of the primary air volume, and the air volume entering the loosening wind caps and ash conveying wind caps is 3:7.

[0011] Further, one end of the air inlet of the ash conveying pipeline is connected to the ash collecting device, and the other end is connected to the furnace. The primary air blown out from the ash collecting device sequentially passes through the gate valve and electric gate valve on the ash conveying pipeline and enters the furnace.

[0012] Further, the entering angle a of the ash conveying pipeline entering the furnace is 25 - 35°, the inlet height H3 of the ash conveying pipeline entering the furnace is greater than or equal to 1000 mm, and the diameter φD of the ash conveying pipeline is 159 - 219 mm.

[0013] Further, a first level gauge is arranged in the ash collecting device.

[0014] Further, a second level gauge is arranged on each of the left and right sides below the wind chamber. The height B of the second level gauge from the bottom of the wind chamber is 200 - 300 mm.

[0015] Further, a slag discharge pipe is provided at the bottom of the furnace, a feeding port is provided on one side of the lower part of the furnace, and an oxygen content meter is provided at the top of the separation device 15.

[0016] Further, a secondary air duct is arranged in the furnace, and an electric air damper is arranged on the lower side of the secondary air duct.

[0017] In summary, the beneficial effects of the present invention are:

[0018] (1) The automatic circulating ash cleaning system for the boiler air chamber of the present invention realizes the problem of ash leakage in the air chamber without shutting down the boiler, and the leaked ash is transported back to the furnace through pneumatic conveying, increasing the ash concentration in the furnace and improving the heat transfer effect of the furnace. At the same time, the primary hot air used for ash transportation is used as the secondary air in the furnace, realizing the recycling of energy, being both safe and energy-saving and environmentally friendly, and meeting the requirements of long-term stable operation of the circulating fluidized bed boiler.

[0019] (2) The present invention solves the problems of low production efficiency and high labor intensity of workers caused by manual ash cleaning in the conventional air chamber that requires shutting down the furnace. Brief Description of the Drawings

[0020] Figure 1 is the structural schematic diagram of the present invention;

[0021] Figure 2 is the schematic diagram of the gas flow direction in the present invention;

[0022] Figure 3 is the structural schematic diagram of the ash collecting device in the present invention;

[0023] Figure 4 is the structural schematic diagram of the ash transportation pipeline in the present invention.

[0024] The reference numerals are as follows:

[0025] 1, primary air duct; 2, air chamber; 3, slag discharge pipe; 4, loosening air duct; 5, ash collecting device; 6, first level gauge; 7, second level gauge; 8, ash transportation pipeline; 9, air distribution plate; 10, air cap; 11, feeding port; 12, secondary air duct; 13, furnace; 14, oxygen meter; 15, separation device; 16, return device; 17, stop valve; 18, electric stop valve; 19, pressure transmitter; 20, gate valve; 21, electric gate valve; 22, electric air damper; 23, loosening air chamber; 24, ash discharge pipe; 25, loosening air cap; 26, ash transportation air cap. Detailed Embodiments

[0026] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with embodiments. The following embodiments are only used to explain the present invention and do not constitute a limitation to the protection scope of the present invention.

[0027] As Figures 1-4As shown in the figure, an automatic circulating ash cleaning system for a boiler air chamber includes a primary air duct 1. At the outlet of the primary air duct 1, there is an air chamber 2 with a pressure of 7 kPa - 10 kPa inside. At the front end of the air chamber 2, there are multiple ash collection devices 5 connected to the inner wall of the lower part of the air chamber 2. The primary air duct 1 and the ash collection devices 5 are connected through a loosening air duct 4. Above the air chamber 2, there is a furnace chamber 13. Between the furnace chamber 13 and the air chamber 2, there are a wind distribution plate 9 and wind caps 10. At the front part of the furnace chamber 13, it is connected to the ash collection devices 5 through an ash conveying pipeline 8. On one side of the upper outlet of the furnace chamber 13, there is a separation device 15. At the lower discharge port of the separation device 15, there is a return material device 16, and the return material device 16 is connected to the lower part of the furnace chamber 13. The pressure at the lower part of the furnace chamber 13 is 0 kPa - 2 kPa. When the system operates, the flue gas carries finer materials and leaves the furnace chamber 13 and enters the separation device 15. The fine materials are separated and collected, and then returned to the furnace chamber through the return material device 16 for continuous circulating combustion. At the top of the separation device 15, there is an oxygen content meter 14 for monitoring the oxygen content in the furnace chamber 13 to maintain the oxygen content in the furnace chamber unchanged.

[0028] In this embodiment, the number of the ash collection devices 5 is arranged according to the width of the air chamber 2, and the number is 1 - 4. The ash collection device 5 includes a loosening air chamber 23. The loosening air chamber 23 is arranged at the bottom of the ash collection device 5. Above the loosening air chamber 23, there are a loosening wind cap 25 and an ash conveying wind cap 26. At the bottom of the ash collection device 5, there is also an ash discharge pipe 24.

[0029] One end of the inlet of the loosening air duct 4 is connected to the primary air duct 1, and the other end is connected to the loosening air chamber 23. The primary air blown out from the primary air duct 1 passes through the stop valve 17, the electric stop valve 18, and the pressure transmitter 19 on the loosening air duct 4 in sequence and enters the loosening air chamber 23.

[0030] Please refer to Figure 3 , in this embodiment, the inlet height H1 of the ash collection device 5 is 100 mm - 300 mm. The selected opening height is convenient for the leakage ash in the air chamber 2 to enter the ash collection device 5, but it should not be too large to avoid affecting the flow field of the air chamber 2. The ash collection height H2 in the ash collection device 5 is greater than or equal to 1000 mm to ensure that a sufficient amount of leakage ash can be stored. The air volume entering the loosening air chamber 23 from the loosening air duct 4 is 3% - 5% of the primary air volume, and the air volume entering the loosening wind cap 25 and the ash conveying wind cap 26 is 3:7. Using the high pressure head in the primary air duct 1, the fine ash particles entering the ash collection device are loosened and conveyed.

[0031] One end of the inlet of the ash conveying pipeline 8 is connected to the ash collection device 5, and the other end is connected to the furnace chamber 13. The primary air blown out from the ash collection device 5 passes through the gate valve 20 and the electric gate valve 21 on the ash conveying pipeline 8 in sequence and enters the furnace chamber 13. As mentioned above, the pressure in the air chamber 2 is 7 kPa - 10 kPa, and the pressure at the lower part of the furnace chamber 13 is 0 kPa - 2 kPa. The ash conveying pipeline 8 uses the pressure difference between the air chamber 2 and the furnace chamber 13 to convey the fine ash particles.

[0032] Please refer to Figure 4 , in this embodiment, the inlet angle α of the ash conveying pipe 8 entering the furnace 13 is 25° - 35°. The setting of the inlet angle not only ensures that the ash in the furnace 13 is not easily introduced into the ash conveying pipe 8, but also facilitates the penetration of the conveying air into the furnace 13. The inlet height H3 of the ash conveying pipe 8 entering the furnace 13 is greater than or equal to 1000 mm, and the diameter φD of the ash conveying pipe 8 is 159 mm - 219 mm, which is convenient for the ash to be returned to the furnace 13.

[0033] In this embodiment, a first level gauge 6 is arranged in the ash collecting device 5 for monitoring the ash leakage capacity in the ash collecting device 5.

[0034] Please refer to Figure 2 , in this embodiment, a second level gauge 7 is arranged on each side of the lower side of the air chamber 2. The height B of the second level gauge 7 from the bottom of the air chamber 2 is 200 - 300 mm, for real-time monitoring of the ash accumulation height in the air chamber 2.

[0035] In this embodiment, a slag discharge pipe 3 is provided at the bottom of the furnace 13 for discharging ash and slag with too large particles. A feed port 11 is provided on one side of the lower part of the furnace 13, and an oxygen content meter 14 is provided at the top of the separation device 15 for monitoring the oxygen content in the furnace 13.

[0036] In this embodiment, a secondary air pipe 12 is arranged in the furnace 13, and an electric damper 22 is arranged on the lower side of the secondary air pipe 12. The electric damper 22 in the secondary air pipe 12 is adjusted according to the oxygen content displayed by the oxygen content meter 14 to reduce the secondary air volume and maintain the oxygen content in the furnace unchanged.

[0037] The working process of an automatic circulating ash cleaning system for the boiler air chamber of the present invention is as follows:

[0038] During the operation of the circulating fluidized bed boiler, a large amount of fine ash leaks from the air distribution plate 9 into the air chamber 2. When the second level gauge 7 monitors that the ash leakage in the air chamber 2 accumulates to the set height, the primary air duct 1 is started, and the primary air blows the ash leakage in the air chamber 2 into the ash collecting device 5. At this time, the valves 17 and the electric valve 18 on the loosening air pipe 4 are opened to loosen the ash in the ash collecting device 5, and then the gate valve 20 and the electric gate valve 21 in the ash conveying pipe 8 are opened. The ash leakage in the air chamber 2 is conveyed back to the furnace 13 again through the pressure difference between the air chamber 2 and the furnace 13. This part of the fine ash enhances the heat transfer effect of the furnace 13 of the circulating fluidized bed boiler, but at the same time increases the oxygen content in the furnace 13;

[0039] In order to maintain the constant oxygen content in the furnace 13, the electric damper 22 in the secondary air duct 12 is adjusted according to the oxygen content displayed by the oxygen meter 14 to reduce the secondary air volume, thereby maintaining the constant oxygen content in the furnace 13. When the first level meter 6 on the ash collection device 5 shows an empty bin, the electric gate valve 21 on the ash conveying pipe 8 and the electric valve 18 on the loosening air duct 4 are closed. At this time, the ash leakage automatic recovery device stops operating.

[0040] An automatic circulating ash cleaning system for a boiler air chamber according to the present invention realizes the problem of ash leakage in the air chamber without shutting down the boiler, and the leaked ash is pneumatically conveyed back to the furnace 13, increasing the ash concentration in the furnace 13 and improving the heat transfer effect in the furnace 13. At the same time, the primary hot air used for ash conveying is used as the secondary air in the furnace 13, realizing the recycling of energy, which is both safe and energy-saving and environmentally friendly, and meets the requirements of long-term stable operation of the circulating fluidized bed boiler.

[0041] It should be noted that in the drawings or the text of the specification, the implementation manners that are not depicted or described are all forms known to those of ordinary skill in the art and are not described in detail. In addition, the above definitions of each component and method are not limited to the specific structures, shapes or manners mentioned in the embodiments.

[0042] It should also be noted that the directional terms mentioned in the embodiments, such as "upper", "lower", "front", "rear", "left", "right", "inner", "outer", etc., are only references to the directions in the drawings and are not used to limit the protection scope of the present application.

[0043] The above description shows and describes the preferred embodiments of the present invention. As mentioned above, it should be understood that the present invention is not limited to the forms disclosed herein, should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be changed within the scope of the inventive concept described herein through the above teachings or the techniques or knowledge in related fields. And the changes and modifications made by those skilled in the art without departing from the spirit and scope of the present invention should all be within the protection scope of the appended claims of the present invention.

Claims

1. An automatic circulating ash cleaning system for a boiler air chamber, characterized in that, It includes a primary air duct (1). At the outlet of the primary air duct (1), there is an air chamber (2). At the front end of the air chamber (2), there are multiple ash collection devices (5) connected to the inner wall of the lower part of the air chamber (2). The primary air duct (1) is connected to the ash collection device (5) through a loosening air duct (4). Above the air chamber (2), there is a furnace chamber (13) connected. Between the furnace chamber (13) and the air chamber (2), there are a distributor plate (9) and tuyeres (10). At the front part of the furnace chamber (13), it is connected to the ash collection device (5) through an ash conveying pipeline (8). On one side of the upper outlet of the furnace chamber (13), there is a separation device (15). At the lower discharge port of the separation device (15), there is a return material device (16), and the return material device (16) is connected to the lower part of the furnace chamber (13). The ash collection device (5) includes a loosening air chamber (23). The loosening air chamber (23) is arranged at the bottom of the ash collection device (5). Above the loosening air chamber (23), there are a loosening tuyere (25) and an ash conveying tuyere (26). At the bottom of the ash collection device (5), there is also an ash discharge pipe (24). One end of the inlet of the loosening air duct (4) is connected to the primary air duct (1), and the other end is connected to the loosening air chamber (23). The primary air blown out from the primary air duct (1) sequentially passes through a stop valve (17), an electric stop valve (18), and a pressure transmitter (19) on the loosening air duct (4) and enters the loosening air chamber (23). The inlet height H1 of the ash collection device (5) is 100 mm - 300 mm. The ash collection height H2 in the ash collection device (5) is greater than or equal to 1000 mm. The air volume entering the loosening air chamber (23) from the loosening air duct (4) is 3% - 5% of the primary air volume, and the air volume entering the loosening tuyere (25) and the ash conveying tuyere (26) is 3:

7.

2. The automatic circulating ash cleaning system for a boiler air chamber according to claim 1, wherein One end of the inlet of the ash conveying pipeline (8) is connected to the ash collection device (5), and the other end is connected to the furnace chamber (13). The primary air blown out from the ash collection device (5) sequentially passes through a gate valve (20) and an electric gate valve (21) on the ash conveying pipeline (8) and enters the furnace chamber (13).

3. The automatic circulating ash cleaning system for a boiler air chamber according to claim 2, characterized in that, The entering angle a of the ash conveying pipeline (8) entering the furnace chamber (13) is 25° - 35°. The inlet height H3 of the ash conveying pipeline (8) entering the furnace chamber (13) is greater than or equal to 1000 mm. The diameter φD of the ash conveying pipeline (8) is 159 mm - 219 mm.

4. The automatic circulating ash cleaning system for a boiler air chamber according to claim 1, wherein A first level gauge (6) is arranged in the ash collection device (5).

5. The automatic circulating ash cleaning system for a boiler air chamber according to claim 1, characterized in that On the left and right sides of the lower side of the air chamber (2), there is a second level gauge (7) each. The height B of the second level gauge (7) from the bottom of the air chamber (2) is 200 mm - 300 mm.

6. The automatic circulation ash cleaning system for a boiler air chamber according to claim 1, characterized in that, At the bottom of the furnace chamber (13), there is a slag discharge pipe (3). On one side of the lower part of the furnace chamber (13), there is a feeding port (11). At the top of the separation device (15), there is an oxygen content meter (14).

7. The automatic circulating ash cleaning system for a boiler air chamber according to claim 1, wherein In the furnace chamber (13), there is a secondary air duct (12). At the lower side of the secondary air duct (12), there is an electric air damper (22).

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