High-efficiency circulating fluidized bed coal-fired boiler air distribution system

Abstract

This application relates to the field of clean coal combustion, and in particular to an efficient circulating fluidized bed coal-fired boiler air distribution system, including an air chamber for supplying air to the combustion chamber, an air distribution plate located near the combustion chamber opening, air caps located on the air distribution plate for supplying air from the air chamber into the combustion chamber, and heat pipes arranged in the combustion chamber to absorb heat. The air chamber is equipped with a flow equalization plate, which has several perforations that are densely distributed throughout, so that the airflow in the air chamber is first processed by the flow equalization plate for uniform distribution, so that the airflow on the air distribution plate can be kept uniform, and the air volume delivered by the air caps on the air distribution plate is relatively consistent, which helps to ensure that the air volume is relatively consistent throughout the combustion chamber and ensures that the pulverized coal combustion is sufficient and uniform.

Description

Technical Field

[0001] This application relates to the field of clean coal combustion, and in particular to an efficient circulating fluidized bed coal-fired boiler air distribution system. Background Technology

[0002] Circulating fluidized bed boilers utilize air and vents introduced into the combustion chamber to contact the pulverized coal, enabling fluidized combustion of the coal and improving combustion efficiency. This process minimizes the formation of nitrogen oxides and provides excellent energy-saving and environmentally friendly characteristics. Uniform air distribution is crucial during combustion. Uneven air distribution leads to uneven combustion in the dense phase zone at the bottom of the combustion chamber, resulting in uneven distribution of pollutants, localized high-value areas, poor fluidization, and increased risk of coking, creating a vicious cycle.

[0003] The existing energy-saving and environmentally friendly circulating fluidized bed system with publication number CN105627300A delivers air into the combustion chamber through a dense array of air caps set on the air distribution plate, so as to contact the pulverized coal.

[0004] Regarding the aforementioned technologies, the air supplied to the air chamber cannot be uniformly distributed across the air distribution plate, resulting in inconsistent airflow from each air hood. This is especially true for large air distribution plates, where the air distribution plate area is large and the number of air hoods is dense. Consequently, the airflow supplied to the combustion chamber is prone to uneven distribution, making it difficult to achieve uniform airflow. Summary of the Invention

[0005] To achieve better uniform air distribution, this application provides an efficient circulating fluidized bed coal-fired boiler air distribution system.

[0006] The high-efficiency circulating fluidized bed coal-fired boiler air distribution system provided in this application adopts the following technical solution.

[0007] A high-efficiency circulating fluidized bed coal-fired boiler air distribution system includes an air chamber for supplying air to the combustion chamber, an air distribution plate located near the opening of the combustion chamber, an air cap located on the air distribution plate and supplying airflow from the air supply chamber into the combustion chamber, and heat pipes arranged in the combustion chamber to absorb heat. The air chamber is equipped with a flow equalization plate, which is densely perforated with several plate holes.

[0008] By adopting the above technical solution, the airflow supplied from one side of the air chamber will first pass through the flow equalization plate, so that the airflow flows through the plate holes, so that the airflow can flow more evenly towards the air distribution plate, so that the air volume at each air cap on the air distribution plate is more uniform, thereby achieving the effect of uniform air supply, making the air volume in the combustion chamber more uniform, and improving the completeness and uniformity of pulverized coal combustion.

[0009] Optionally, the air distribution plate is provided with several air guide valves on the side facing the air chamber. Each air guide valve corresponds to one or more rows of air caps to control the air volume of the air caps. The air caps are provided with several measuring parts to monitor the combustion in the combustion chamber. Each air guide valve corresponds to one measuring part.

[0010] By adopting the above technical solution, the air guide valve can be adjusted according to the combustion conditions in the combustion chamber fed back by the measuring unit, so that the combustion in the combustion chamber is more complete and uniform.

[0011] Optionally, the measuring unit includes an oxygen meter, a pressure gauge, and a thermometer, and the air guide valve adjusts each parameter to be consistent in the order of thermometer, pressure gauge, and oxygen meter.

[0012] By adopting the above technical solution, the combustion chamber can be measured in real time from three aspects: oxygen content, pressure and temperature. This allows for comprehensive monitoring of the combustion uniformity within the combustion chamber, and temperature is adjusted as the highest priority indicator. This helps to reduce the cost of combustion uniformity and subsequent pollutant prediction and removal.

[0013] Optionally, the heat pipe is located at the end of the hood away from the air distribution plate, and the heat pipe is arranged in a grid pattern.

[0014] By adopting the above technical solution, the temperature in the combustion chamber, especially in the combustion chamber with a large bed surface, is made more uniform by utilizing the heat pipe principle.

[0015] Optionally, the plate holes are divided into arrays, and the flow equalization plate is provided with a sealing baffle for each group of plate holes. The sealing baffle can close up to half of the plate holes in the corresponding group.

[0016] By adopting the above technical solution, when the gas flow rate is low at a certain point in the combustion chamber, the surrounding closed baffles at the corresponding location can be rotated to seal the corresponding plate holes, thereby rapidly improving the uniformity of airflow in the combustion chamber.

[0017] Optionally, a baffle motor is provided outside the air chamber for each closed baffle, and the output shaft of the baffle motor is detachably connected to a rotating sleeve that drives the closed baffle to rotate.

[0018] By adopting the above technical solution, the baffle motor can be disassembled for maintenance, which is more convenient.

[0019] Optionally, the closed baffle is provided with a sealing sleeve for each plate hole on the side facing the flow equalization plate, and the closed baffle is slidably connected with a plug for each sealing sleeve. The plug is inserted into the sealing sleeve so that the sealing sleeve is tightly attached to the inner wall of the plate hole.

[0020] By adopting the above technical solution, when the sealing plate baffle is attached to the air distribution plate, the plug moves into the sealing sleeve, so that the sealing sleeve is tightly attached to the inner wall of the plate hole, thereby improving the sealing performance of the plate hole that needs to be sealed and helping to improve the flow equalization effect that the flow equalization plate can achieve.

[0021] Optionally, the rotating sleeve is coaxially fixedly connected with a half gear, and a half ring gear is coaxially fixedly connected at the rotation point inside the closed baffle. The radius of the half gear is half that of the half ring gear. The half gear can mesh with the half ring gear. A driving gear can mesh on the side of the half gear away from the inner ring of the half ring gear. An even number of driving gears are provided, and two adjacent driving gears mesh. A plug rack that can drive the plug to move is slidably connected inside the closed baffle. The plug rack and the half gear mesh with the two driving gears that are furthest apart.

[0022] By adopting the above technical solution, the half gear can drive the half ring gear to rotate. When the closed baffle is attached to the flow equalization plate, the half gear disengages from the half ring gear and meshes with the driving gear. This makes the continued rotation of the rotating sleeve at this time not cause the closed baffle to rotate, but allows the plug to move and be smoothly inserted into the plate hole, so that the sealing sleeve can be tightly attached to the inner wall of the plate hole.

[0023] Optionally, the insert rack is fixedly connected to a synchronization plate, and the synchronization plate is fixedly connected to all the inserts in the corresponding closed baffle.

[0024] By adopting the above technical solution, the plugs in the same closed baffle can move synchronously, and the setting of related structures can also be reduced.

[0025] Optionally, the inside of the closed baffle is provided with a magnetic component that can attract the synchronization plate on the side away from the flow equalization plate.

[0026] By adopting the above technical solution, when the plug-in retracts into the closed baffle, the magnetic component can attract the synchronization plate, so that when the second half gear disengages from the driving gear, the plug-in is not easy to move at will.

[0027] In summary, this application includes at least one of the following beneficial effects:

[0028] 1. It can comprehensively realize multiple functions such as primary air enhanced flow equalization, bed temperature equalization, and precise parameter detection and adjustment for various circulating fluidized bed units, especially large fluidized bed units. Therefore, it is of great significance for stable combustion in the dense phase zone and the overall operation capability of the fluidized bed unit.

[0029] 2. The flow equalization plate also has a good anti-slag leakage effect, effectively extending the operating cycle of the air chamber and air cap;

[0030] 3. During the gas-solid flow process, the gridded heat pipe can further promote the uniformity of gas-solid flow and combustion, and ensure the most important operating parameter in the dense phase region—temperature uniformity—at various loads.

[0031] 4. Real-time measurement of key operating parameters (oxygen, temperature, and pressure) in the dense phase zone, i.e., the harsh environment of the combustion chamber, and feedback to the electric air guide valve for adjustment, plays an important role in predicting slag leakage, preventing coking, and ensuring uniform combustion of air and coal.

[0032] 5. It can ensure the uniformity of combustion in the dense phase zone of the unit under various loads, and when the temperature is guaranteed, the distribution of various pollutants, especially nitrogen oxides, can be predicted more accurately. It has important guiding significance for the precise control of limestone dry desulfurization in the furnace and ammonia injection in the furnace or ammonia injection in the horizontal flue for denitrification. Attached Figure Description

[0033] Figure 1 This is a side view of the present application from the side where the air distribution plate is located along its length.

[0034] Figure 2 This is a cross-sectional view of the upper part of the air chamber with the flow equalization plate installed, and a schematic diagram of the structure with half of a closed baffle cut off.

[0035] Figure 3 yes Figure 2 Enlarged view of point A in the middle;

[0036] Figure 4 These are two simplified schematic diagrams showing the sequential and staggered arrangement of heat pipes.

[0037] Explanation of reference numerals in the attached drawings: 1. Air chamber; 22. Magnetic component; 3. Air distribution plate; 31. Baffle motor; 32. Rotating sleeve; 33. Sealing sleeve; 34. Insert; 35. Half gear; 36. Half ring gear; 37. Drive gear; 38. Synchronizing plate; 39. Insert rack; 4. Air cap; 41. Flow equalization plate; 42. Plate hole; 43. Sealing baffle; 44. Air guide valve; 45. Measuring section; 46. Oxygen meter; 47. Pressure gauge; 48. Thermometer; 49. Heat pipe. Detailed Implementation

[0038] The present application will be further described in detail below with reference to the accompanying drawings.

[0039] This application discloses an efficient circulating fluidized bed coal-fired boiler air distribution system, referring to... Figure 1It includes a wind chamber 1 with its bottom connected to an external blower on one vertical side. A horizontal air distribution plate 3 is fixedly connected to the upper opening of the wind chamber 1. Several rows of air caps 4 are evenly fixedly connected to the upper surface of the air distribution plate 3. The rows of air caps 4 are evenly distributed along the length of the air distribution plate 3. Several air caps 4 are evenly distributed along the width of the air distribution plate 3. The air caps 4 are connected to the inside of the wind chamber 1 so that each air cap 4 sends out airflow from the combustion chamber first.

[0040] Reference Figure 1 and Figure 2 A horizontal flow equalization plate 41 is fixedly connected inside the air chamber 1. The length direction of the flow equalization plate 41 is consistent with the length direction of the air distribution plate 3. Several plate holes 42 are evenly and vertically perforated on the upper surface of the flow equalization plate 41, so that the airflow sent into the air chamber 1 from one side first passes through the flow equalization plate 41 for even distribution, so that the airflow finally sent into the combustion chamber from each air cap is relatively uniform. Several closed baffles 43 are provided on the upper surface of the flow equalization plate 41. The closed baffles 43 are rotatably connected to the vertical inner wall of the air chamber 1 along its length direction. The rotation axis of the closed baffles 43 is consistent with the width direction of the air distribution plate 3. The plate holes 42 located in the same width direction of the flow equalization plate 41 are in a row. Each even-numbered row of plate holes 42 is grouped together and corresponds to a closed baffle 43. Each closed baffle 43 can block half of the plate holes 42 in the corresponding group, so that a significant adjustment can be made quickly when there is a large degree of unevenness in the air supply of the wind cap 4. It is especially suitable for plate holes 42 with a high opening ratio and a large inner diameter on the flow equalization plate 41.

[0041] Reference Figure 2 and Figure 3 Each closed baffle 43 on the vertical outer wall of the air chamber 1 is detachably connected to a baffle motor 31. The output shaft of the baffle motor 31 is keyed to a rotating sleeve 32, which is rotatably connected to the air chamber 1 and extends into the interior of the closed baffle 43. A semi-ring gear 36 is fixedly connected inside the closed baffle 43. The central angle of the semi-ring gear 36 can be appropriately greater than 90°, for example, the central angle range of the semi-ring gear 36 is 95° to 110°. The axis of the semi-ring gear 36 is the same as the rotation axis of the closed baffle 43. A semi-ring gear 35 is coaxially fixedly connected to one end of the rotating sleeve 32 in the closed baffle 43. The semi-ring gear 35 has teeth only in half the range of the central angle. The semi-ring gear 35 can mesh with the semi-ring gear 36. The diameter of the semi-ring gear 35 is half the diameter of the semi-ring gear 36, so that when the semi-ring gear 35 rotates half a turn, the semi-ring gear 36 is driven to rotate a quarter turn, so that the closed baffle 43 can rotate from vertical to horizontal, so that the closed baffle 43 is close to the upper surface of the flow equalization plate 41 to block the plate hole 42.

[0042] Reference Figure 3Several inserts 34 are slidably connected inside the closed baffle 43. Each insert 34 corresponds to a plate hole 42 that the closed baffle 43 needs to block. When the closed baffle 43 is horizontal, the insert 34 moves vertically out of the closed baffle 43 and is inserted into the plate hole 42. Several sealing sleeves 33 are fixedly connected to the side of the closed baffle 43 facing the flow equalization plate 41. The sealing sleeves 33 can be made of rubber to be deformable. Each sealing sleeve 33 corresponds to an insert 34, so that when the insert 34 is inserted into the corresponding plate hole 42, the sealing sleeve 33 is simultaneously inserted into the plate hole 42. The sealing sleeve 33 is squeezed between the inner wall of the plate hole 42 and the insert 34, so that the plate hole 42 with the sealing sleeve 33 squeezed in has good sealing performance, which can further improve the control of the flow equalization effect of the flow equalization plate 41.

[0043] Reference Figure 3 Inside the closed baffle 43, a driving gear 37 is rotatably connected to the side of the half gear 35 away from the half ring gear 36. An even number of driving gears 37 are provided, with adjacent driving gears 37 meshing. A insert rack 39 meshes with the driving gear 37 away from the half gear 35. When the closed baffle 43 is horizontal, the insert rack 39 slides vertically inside the closed baffle 43. A synchronization plate 38 is fixedly connected to one end of the insert rack 39 near the insert 34. The synchronization plate 38 is fixedly connected to all the inserts 34 in the corresponding closed baffle 43. This ensures that after the closed baffle 43 rotates from vertical to horizontal, the continued rotation of the half gear 35 will not drive the half ring gear 36 to rotate. The half gear 35 will mesh with the driving gear 37, causing the insert rack 39 to move vertically downwards, allowing the inserts 34 to be inserted into the corresponding plate holes 42, achieving better sealing of the plate holes 42. Meanwhile, a magnetic component 22 is fixedly connected inside the closed baffle 43, so that when the plug 34 is retracted into the closed baffle 43 and the half gear 35 is no longer engaged with the driving gear 37, the magnetic component 22 can be attracted to the synchronization plate 38, making it difficult for the plug 34 to move again.

[0044] Meanwhile, the half-ring gear 36, half-gear 35, drive gear 37, insert rack 39 and sealing sleeve 33 all have high temperature resistance and wear resistance to adapt to the high temperature and particulate matter environment inside the air chamber 1.

[0045] Reference Figure 1Several air guide valves 44 are fixedly connected to the lower surface of the air distribution plate 3. The length direction of the air guide valves 44 is consistent with the width direction of the air distribution plate 3. The air guide valves 44 can correspond to one to four rows of air caps 4 for air volume control. Some air caps 4 are equipped with several measuring parts 45. For example, every four square meters on the air distribution plate 3 is a region, and a measuring part 45 is set in the air cap 4 at the center of the region. This allows the measuring parts 45 to be protected by the air caps, extending their service life in the harsh environment at the bottom of the combustion chamber. Each measuring part 45 can include an oxygen content meter 46, a pressure gauge 47, and a thermometer 48 to monitor the oxygen content, pressure, and temperature in the combustion chamber in real time. The measuring parts 45 and the air guide valves 44 are electrically connected to an external controller, allowing the air guide valves 44 to adjust according to the parameters input to the external controller from each measuring part 45, ensuring uniform and complete combustion throughout the combustion chamber. Furthermore, considering the uniformity of combustion and the cost of subsequent pollutant prediction and removal, the air guide valve 44 is adjusted according to the priority order of temperature > pressure > oxygen content.

[0046] The specific adjustment of the air guide valve 44 is illustrated with appropriate examples. When operating normally, the oxygen meter should be approximately equal to the oxygen content of the air, which is 21%. When the oxygen meter reading is significantly less than 21%, it indicates that there is a low air velocity problem or a slag leakage problem, and the fluidizing air volume in this area needs to be increased.

[0047] The optimal operating conditions correspond to similar temperatures and pressures at each measuring point. When local temperature and pressure readings are low, it indicates poor fluidization or insufficient airflow in that area, requiring an increase in the fluidization airflow.

[0048] When the local temperature measurement reading is low but the pressure reading is normal, it indicates that the amount of fuel falling into or diffusing into the area is insufficient, and the fluidizing air volume in the area needs to be reduced.

[0049] When both the temperature and pressure readings are high, it indicates that there is too much fluidizing air and fuel in the area, and adjustments need to be made from the coal feeding side, while reducing the air volume in the corresponding area.

[0050] In areas where fluidizing air needs to be increased, the opening of the corresponding air guide valves should be increased accordingly, while the opening of adjacent air guide valves should be decreased accordingly. If adjacent oxygen levels are also low, the opening of the corresponding adjacent air guide valves should be increased simultaneously until the parameters of each area are normal.

[0051] Reference Figure 1 and Figure 4 A heat pipe 49 is fixedly connected to the upper end of the air cap 4. The heat pipe 49 is arranged in a grid pattern. For example, the heat pipe 49 can be arranged in a straight or staggered manner so that when the area of ​​the large bed surface, i.e. the air distribution plate 3 is large, the gridded heat pipe 49 can promote the diffusion of particles, the uniform blowing of primary air and the uniformity of gas-solid flow, which is beneficial to the distribution of bed pressure and bed temperature.

[0052] The implementation principle of an efficient circulating fluidized bed coal-fired boiler air distribution system according to an embodiment of this application is as follows: the air supplied to the air chamber is first distributed evenly by the flow equalization plate 41, and then the air is evenly delivered from the air cap 4 on the air distribution plate 3, so that the air volume is uniform throughout the combustion chamber, and the combustion is complete and uniform.

[0053] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A high-efficiency circulating fluidized bed coal-fired boiler air distribution system, comprising an air chamber (1) for feeding air into a combustion chamber, an air distribution plate (3) arranged at the air chamber (1) near an opening of the combustion chamber, an air cap (4) arranged at the air distribution plate (3) and used for feeding air flow in the air chamber (1) into the combustion chamber, and a heat pipe (49) arranged in the combustion chamber and used for absorbing heat, characterized in that: The air chamber (1) is provided with a flow equalization plate (41), which is densely covered with several plate holes (42). The plate holes (42) are divided into groups, and the flow equalization plate (41) is provided with a sealing baffle (43) for each group of plate holes (42). The sealing baffle (43) can seal up to half of the plate holes (42) in the corresponding group. The air chamber (1) is provided with a baffle motor (31) for each sealing baffle (43) outside. The output shaft of the baffle motor (31) is detachably connected to a rotating sleeve (32) that drives the sealing baffle (43) to rotate. The sealing baffle (43) facing the flow equalization plate (41) is provided with a sealing sleeve (33) for each plate hole (42). The sealing baffle (43) is slidably connected with a plug (34) for each sealing sleeve (33). The plug (34) is inserted into the sealing sleeve (33) so that the sealing sleeve (33) is tightly attached to the inner wall of the plate hole (42).

2. The high-efficiency circulating fluidized bed coal-fired boiler air distribution system according to claim 1, characterized in that: The air distribution plate (3) is provided with several air guide valves (44) on the side facing the air chamber (1). Each air guide valve (44) corresponds to one or more rows of air caps (4) to control the air volume of the air caps (4). The air caps (4) are provided with several measuring parts (45) to monitor the combustion in the combustion chamber. Each air guide valve (44) corresponds to one measuring part (45).

3. The high-efficiency circulating fluidized bed coal-fired boiler air distribution system according to claim 2, characterized in that: The measuring unit (45) includes an oxygen meter (46), a pressure gauge (47) and a thermometer (48). The air guide valve (44) adjusts the parameters to be consistent in the order of the thermometer (48), pressure gauge (47) and oxygen meter (46).

4. The high-efficiency circulating fluidized bed coal-fired boiler air distribution system according to claim 1, characterized in that: The heat pipe (49) is located at the end of the vent cap (4) away from the air distribution plate (3), and the heat pipe (49) is arranged in a grid pattern.

5. The high-efficiency circulating fluidized bed coal-fired boiler air distribution system according to claim 1, characterized in that: The rotating sleeve (32) is coaxially fixedly connected to a half gear (35), and a half ring gear (36) is coaxially fixedly connected at the rotation point inside the closed baffle (43). The radius of the half gear (35) is half that of the half ring gear (36). The half gear (35) can mesh with the half ring gear (36). A driving gear (37) can mesh on the side of the half gear (35) away from the inner ring of the half ring gear (36). An even number of driving gears (37) are provided, and two adjacent driving gears (37) mesh. A plug rack (39) that can drive the plug (34) to move is slidably connected inside the closed baffle (43). The plug rack (39) and the half gear (35) mesh with the two driving gears (37) that are furthest apart.

6. The high-efficiency circulating fluidized bed coal-fired boiler air distribution system according to claim 5, characterized in that: The insert rack (39) is fixedly connected to a synchronization plate (38), and the synchronization plate (38) is fixedly connected to all the inserts (34) in the corresponding closed baffle (43).

7. The high-efficiency circulating fluidized bed coal-fired boiler air distribution system according to claim 6, characterized in that: The closed baffle (43) has a magnetic component (22) on the side away from the flow equalization plate (41) that can attract the synchronization plate (38).

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