Anti-surge structure for cooling fan of CAP series nuclear power station

Abstract

The utility model belongs to the technical field of cooling fans, and particularly relates to an anti-surge structure for a cooling fan of a CAP series nuclear power plant, the anti-surge structure comprises a circulation tank, and a flow deflector and a flow guide ring which are positioned in the circulation tank, the circulation tank is positioned between an air inlet end of an air duct and a blade, the flow guide ring is sleeved at the middle position of the circulation tank, and the flow guide ring is arranged in the circulation tank. A buffer channel is formed by a gap between the flow guide ring and the circulation groove, the flow guide ring is of a conical barrel structure, the flow guide pieces are arranged at intervals in an annular array with the axis of the circulation groove as the center, and the buffer channel is divided by the flow guide pieces to form a plurality of divided channels. And vortex air mass enters the division channel along the upper part of the flow deflector to surround, then enters the exhaust channel and is exhausted. According to the anti-surge structure, vortex generation is restrained, meanwhile, gas circulation is smooth, it is guaranteed that the cooling fan can stably operate within the small flow range, a surge area is eliminated, and the efficient operation area of the fan is enlarged.

Description

Technical Field

[0001] The utility model belongs to the technical field of cooling fans, and particularly relates to an anti-surge structure for a cooling fan of a CAP series nuclear power plant. Background Technique

[0002] When the cooling fan is running, on the one hand, the air flow generates a strong impact load on the inner wall of the air duct after being accelerated by the impeller group, forcing the fan to vibrate violently; on the other hand, eddy currents are formed at the leading edge of the blade, causing the air flow to oscillate back and forth at the blade root, resulting in fatigue fracture of the blade and unstable operation of the fan, and finally leading to the formation of an obvious surge zone and an unstable operation zone for the fan. The above two aspects affect the service life of the cooling fan to varying degrees. The special working environment of the control rod drive mechanism of the CAP series nuclear power plants requires that the cooling fan cannot have large vibrations, and at the same time requires a long service life of the cooling fan and an efficient operation area with a margin of more than 30%.

[0003] At present, the anti-surge structures adopted by cooling fans on the market have solved the surge problem of the fans to a certain extent and improved the high-efficiency operation area of the fans. However, there is still a problem of large vibration values of the fans in the application within a small air flow range of the fan assemblies with this structure. Some manufacturers have tried to use elastic shock absorbers to make up for the problem of large vibration values of the fans, but the effect is not obvious, and the vibration of the fans seriously affects the service life of the cooling fans. Content of the Utility Model

[0004] In order to solve the problems existing in the above-mentioned prior art, the utility model provides an anti-surge structure for a cooling fan of a CAP series nuclear power plant. While suppressing the generation of eddy currents, the anti-surge structure enables smooth gas flow, ensures that the fan assembly can operate stably within a small flow range, eliminates the surge zone, and expands the high-efficiency operation area of the fan.

[0005] The specific technical solution adopted by the utility model is as follows:

[0006] An anti-surge structure for a cooling fan of a CAP series nuclear power plant, the cooling fan includes an air duct, blades and a motor. The blades have the freedom of rotation by means of the motor. A vertical exhaust passage is formed in the air duct. The anti-surge structure includes a circulation groove, a guide vane and a guide ring located in the circulation groove. The circulation groove is located between the air inlet end of the air duct and the blades. The guide ring is sleeved at the middle position of the circulation groove. The gap between the guide ring and the circulation groove forms a buffer passage. The guide ring has a conical cylinder structure. The guide vanes are arranged in a plurality of groups at intervals in a circumferential array with the axis of the circulation groove as the center. The buffer passage is divided into a plurality of divided passages by the guide vanes. The eddy current air mass enters the divided passages along the upper part of the guide vanes, circulates and then enters the exhaust passage and is discharged.

[0007] The gap between the guide ring and the upper end surface of the annular flow channel forms the intake end of the buffer channel, and the gap between the guide ring and the lower end surface of the annular flow channel forms the exhaust end of the buffer channel.

[0008] The diameter of the end of the guide ring near the intake side of the exhaust channel is larger than the diameter of the end of the guide ring near the exhaust side of the exhaust channel.

[0009] The included angle between the extension line of the inclined plane of the guide ring and the axis of the annular flow channel is 25 - 35°.

[0010] The number of the guide vanes is an odd number within the range of 23 - 31.

[0011] The distance between the upper surface of the guide ring and the lower surface of the blade is 10 - 15 mm.

[0012] A plurality of fixing rods are arranged on the peripheral side of the motor, and the motor is fixedly connected to the peripheral side of the air duct by means of the fixing rods and suspended in the air duct.

[0013] The guide vanes include primary guide vanes and secondary guide vanes. The top of the primary guide vanes is flush with the upper surface of the guide ring, the bottom of the primary guide vanes is fixedly connected to the bottom of the guide groove, the top of the secondary guide vanes is flush with the upper surface of the guide ring, the bottom of the secondary guide vanes is fixedly connected to the bottom of the guide groove, and the secondary guide vanes are located between adjacent primary guide vanes.

[0014] The beneficial effects of the present utility model are:

[0015] In the present utility model, a buffer channel is additionally provided to form an anti-surge structure. While suppressing the generation of eddy currents, the gas flow is made smooth, ensuring that the cooling fan can operate stably within a small flow range, eliminating the surge zone, and expanding the high-efficiency operation area of the fan.

[0016] The air flow entering the air duct forms eddy currents at the front end of the blades under the action of the centrifugal force generated by the rotation of the blades. First, the inclined guide ring aggregates the small air currents, and through the blockage of the annular groove, the air mass enters the buffer channel. The high-speed flowing air mass is buffered by the guide vanes and the guide ring, smoothing the disturbed air flow, and part of the energy of the air mass is absorbed, thereby reducing the impact load of the air flow on the side wall of the air duct, and the vibration value of the fan also weakens accordingly. At the same time, the guide vanes divide the buffer channel into multiple independent buffer channels, dividing the larger air mass that agglomerates into one into multiple groups of smaller air masses, making it easier to absorb the energy of the air mass and reducing the vibration value. Description of the Drawings

[0017] Figure 1 is a schematic structural diagram of the present utility model;

[0018] Figure 2 is Figure 1Enlarged schematic view of part A;

[0019] Figure 3 Schematic side view of the flow guiding ring and the flow guiding vanes;

[0020] Figure 4 Test data diagram of the fan;

[0021] In the drawings, 1 is the air duct, 2 is the blade, 3 is the motor, 4 is the circulation groove, 5 is the flow guiding ring, 6 is the fixing rod, 7 is the primary flow guiding vane, and 8 is the secondary flow guiding vane. Detailed implementation manners

[0022] The present utility model will be further described below in conjunction with the drawings and specific embodiments:

[0023] Specific embodiment, as Figure 1-2 shown, the present utility model provides an anti-surge structure for a cooling fan of a CAP series nuclear power plant. The cooling fan includes an air duct 1, blades 2, and a motor 3. The blades 2 have a degree of freedom of rotation by means of the motor 3. A vertical exhaust passage is formed in the air duct 1. The anti-surge structure includes a circulation groove 4 and flow guiding vanes and a flow guiding ring 5 located in the circulation groove 4. The circulation groove 4 is located between the air inlet end of the air duct 1 and the blades 2. The flow guiding ring 5 is sleeved at the middle position of the circulation groove 4. The gap between the flow guiding ring 5 and the circulation groove 4 forms a buffer passage. The flow guiding ring 5 has a conical tube structure. The flow guiding vanes are arranged at intervals in a circular array centered on the axis of the circulation groove 4 in multiple groups. The buffer passage is divided into multiple groups of divided passages by the flow guiding vanes. The eddy air mass enters the divided passages along the upper side of the flow guiding vanes, circulates, and then enters the exhaust passage and is discharged.

[0024] Due to the special working environment of the control rod drive mechanism of the CAP series nuclear power plant, it is required that the cooling fan cannot have large vibrations, and at the same time, the cooling fan has a long service life and an efficient operation area with a margin of more than 30%. However, the vibration reduction effect of the current anti-surge device is limited and cannot meet the working environment requirements of the control rod drive mechanism of the CAP series nuclear power plant.

[0025] Therefore, a buffer channel is added in the present utility model to form an anti-surge structure. The airflow entering the air duct 1 forms a vortex at the front end of the blade 2 under the action of the centrifugal force generated by the rotation of the blade 2. Due to the blockage of the annular groove, the air mass can only enter the buffer channel. The high-speed flowing air mass is buffered by the guide vanes and the guide ring 5, and most of its energy is absorbed, thereby reducing the impact load of the airflow on the side wall of the air duct 1, and the vibration value of the fan is also weakened accordingly. At the same time, the guide vanes divide the buffer channel into multiple independent buffer channels, so that the larger air mass agglomerated into one is divided into multiple groups of smaller air masses, which is more likely to absorb the energy of the air mass and reduce the vibration value. The anti-surge structure in the present utility model suppresses the generation of vortices while ensuring smooth gas flow, ensuring that the cooling fan can operate stably within a small flow range, eliminating the surge zone, and expanding the high-efficiency operation area of the fan.

[0026] The gap between the upper end surface of the guide ring 5 and the annular groove 4 forms the intake end of the buffer channel, and the gap between the lower end surface of the guide ring 5 and the annular groove 4 forms the exhaust end of the buffer channel. Through the position setting of the guide ring 5, the flow path of the air mass is an annular path. The air mass with reduced energy along the annular path re-enters the main air flow along the exhaust end of the buffer channel and enters the exhaust channel with the main air flow to be discharged.

[0027] The diameter of the end of the guide ring 5 close to the intake side of the exhaust channel is larger than the diameter of the end of the guide ring 5 close to the exhaust side of the exhaust channel. The intake end of the guide ring 5 is inclined towards the exhaust channel. By the inclined guide ring 5, the intake end area of the buffer channel is increased, and at the same time, part of the airflow is blocked from gathering inward by the inclination of the guide ring 5, increasing the pressure of the main air flow, thereby resisting the centrifugal action generated by the blade 2 and hindering the generation of part of the vortices.

[0028] The included angle between the extension line of the inclined plane of the guide ring 5 and the axis of the annular groove 4 is 25 - 35°.

[0029] The number of the guide vanes is an odd number within the range of 23 - 31.

[0030] The distance between the upper surface of the guide ring 5 and the lower surface of the blade 2 is 10 - 15 mm.

[0031] As Figure 4 shown, through the control variable method, after repeated tests on different angles of the guide ring 5, different numbers of guide vanes, and different positions of the guide ring 5, it is verified that when the guide ring 5 is located 10 - 15 mm below the center line of the blade 2, the included angle of the guide ring 5 is 25 - 35°, and the number of guide vanes is an odd number within the range of 23 - 31, the vibration degree of the cooling fan is the smallest and the maximum high-efficiency operation area is the largest, and the maximum high-efficiency operation area is more than 45%.

[0032] A plurality of fixing rods 6 are arranged on the periphery of the motor 3. The motor 3 is fixedly connected to the periphery of the air duct 1 by means of the fixing rods 6 and suspended in the air duct 1. Since the vibration value of the traditional fan is relatively large, in order to ensure the stable operation of the motor 3, the motor 3 is generally wrapped with a protective cover. However, the protective cover increases the overall weight of the fan, occupies a large amount of space in the exhaust passage and affects the ventilation volume of the fan. In the present utility model, due to the improvement of the guide vanes and the guide ring 5, the vibration value of the fan is greatly reduced. Therefore, the motor 3 can operate stably without a protective cover, and only the plurality of fixing rods 6 are needed to fix the motor 3, the structure is simpler, the overall weight of the fan is reduced and the ventilation volume of the fan is increased.

[0033] As Figure 3 shown, the guide vanes include primary guide vanes 7 and secondary guide vanes 8. The top of the primary guide vanes 7 is flush with the upper surface of the guide ring 5, and the bottom of the primary guide vanes 7 is fixedly connected to the bottom of the guide groove. The top of the secondary guide vanes 8 is flush with the upper surface of the guide ring 5, and the bottom of the secondary guide vanes 8 is fixedly connected to the bottom of the guide groove. The secondary guide vanes 8 are located between adjacent primary guide vanes 7. By arranging the primary guide vanes 7 at intervals, the buffer passage is divided into a plurality of relatively wide primary buffer passages. The secondary guide vanes 8 are arranged along the bottom of the guide ring 5 and are located in the primary buffer passages. Taking the horizontal plane where the bottom of the guide ring 5 is located as the boundary, the secondary guide vanes 8 divide the half of the primary buffer passage close to the exhaust end into two relatively narrow secondary buffer passages. The air mass first enters the relatively wide primary buffer passage to form a primary buffer, and the air mass after the primary buffer enters the secondary buffer passage for a secondary buffer. The energy in the air mass can be gradually absorbed through the two buffers, avoiding large-amplitude vibration at the circulation groove 4 caused by only unloading the air mass once.

Claims

1. A surge-proof structure for the cooling fan of a CAP series nuclear power plant. The cooling fan includes a wind barrel (1), blades (2), and a motor (3). The blades (2) have the freedom of rotation by means of the motor (3). A vertical exhaust passage is formed inside the wind barrel (1). The surge-proof structure includes a circulation groove (4), as well as guide vanes and a guide ring (5) located inside the circulation groove (4). The circulation groove (4) is located between the air inlet end of the wind barrel (1) and the blades (2), and is characterized in that, The flow guide ring (5) is sleeved at the middle position of the circulation groove (4). The gap between the flow guide ring (5) and the circulation groove (4) forms a buffer channel. The flow guide ring (5) is in a conical cylinder structure. Multiple groups of the flow guide vanes are arranged at intervals in an annular array centered on the axis of the circulation groove (4). The buffer channel is divided into multiple groups of divided channels by the flow guide vanes. The eddy air mass enters the divided channels along the upper side of the flow guide vanes, circulates and then enters the exhaust channel and is discharged.

2. The anti-surge structure for the cooling fan of the CAP series nuclear power plant according to claim 1, characterized in that, The gap between the upper end face of the flow guide ring (5) and the circulation groove (4) forms the air inlet end of the buffer channel, and the gap between the lower end face of the flow guide ring (5) and the circulation groove (4) forms the air outlet end of the buffer channel.

3. The anti-surge structure for the cooling fan of the CAP series nuclear power plant according to claim 1, characterized in that, The diameter of the end of the flow guide ring (5) close to the air inlet side of the exhaust channel is larger than the diameter of the end of the flow guide ring (5) close to the air outlet side of the exhaust channel.

4. A surge prevention structure for a cooling fan of a CAP series nuclear power plant according to claim 1, characterized in that, The included angle between the extension line of the inclined plane of the flow guide ring (5) and the axis of the circulation groove (4) is 25 - 35°.

5. A surge protection structure for a cooling fan of a CAP series nuclear power plant according to claim 1, characterized in that, The number of the flow guide vanes is an odd number within the range of 23 - 31.

6. The anti-surge structure for the cooling fan of the CAP series nuclear power plant according to claim 1, characterized in that, The distance between the upper surface of the flow guide ring (5) and the lower surface of the blade (2) is 10 - 15 mm.

7. A surge prevention structure for a cooling fan of a CAP series nuclear power plant according to claim 1, characterized in that, Multiple groups of fixing rods (6) are arranged on the periphery of the motor (3). The motor (3) is fixedly connected to the periphery of the air duct (1) by means of the fixing rods (6) and is suspended in the air duct (1).

8. A surge prevention structure for a cooling fan of a CAP series nuclear power plant according to claim 1, characterized in that, The flow guide vanes include primary flow guide vanes (7) and secondary flow guide vanes (8). The top of the primary flow guide vanes (7) is flush with the upper surface of the flow guide ring (5), and the bottom of the primary flow guide vanes (7) is fixedly connected to the bottom of the flow guide groove. The top of the secondary flow guide vanes (8) is flush with the upper surface of the flow guide ring (5), and the bottom of the secondary flow guide vanes (8) is fixedly connected to the bottom of the flow guide groove. The secondary flow guide vanes (8) are located between adjacent primary flow guide vanes (7).

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