Siphon direct-drive tubular turbine for low or ultra-low head

Abstract

The invention discloses a siphon type direct drive tubular turbine suitable for low head or ultra-low head, comprising a siphon pipe, a direct drive type generator set installed in the siphon pipe, a stator of the direct drive type generator set fixedly installed on the inner wall of the siphon pipe, and a runner of the direct drive type generator set connected to the stator through a bearing. The siphon type direct drive tubular turbine suitable for low head or ultra-low head of the invention solves the problem of poor sealing between dynamic and static parts caused by the main shaft of the siphon type turbine passing through the siphon pipe in the prior art.

Description

Technical Field

[0001] The invention belongs to the technical field of water turbines and relates to a siphon type direct-drive tubular water turbine suitable for low water head or ultra-low water head. Background Art

[0002] my country's coastal areas are rich in hydropower resources. However, with the gradual development of high-head hydropower resources and the growth of electricity demand in coastal areas, the demand for the development of low-head hydropower resources has continued to rise. Compared with high-head power stations, low-head power stations have increased unit size, civil engineering workload and unit investment cost under the same output. Most traditional low-head power stations use cross-flow turbine units. When operating under low or ultra-low heads, there are many problems such as low operating efficiency, severe cavitation of the units and short operating cycle. Siphon turbines have the advantages of easy installation and maintenance, stable operation, etc., and are very suitable for the development of low-head or ultra-low-head hydropower resources. However, in the prior art, the main shaft of the siphon turbine needs to pass through the siphon pipe, resulting in poor sealing between the moving and static components. Summary of the invention

[0003] The purpose of the present invention is to provide a siphon type direct drive tubular turbine suitable for low head or ultra-low head, which solves the problem of poor sealing between moving and static parts caused by the main shaft of the siphon type turbine passing through the siphon tube in the prior art.

[0004] The technical solution adopted by the present invention is a siphon-type direct-drive cross-flow turbine suitable for low head or ultra-low head, including a siphon pipe, in which a direct-drive generator set is installed, the stator of the direct-drive generator set is fixedly installed on the inner wall of the siphon pipe, and the impeller of the direct-drive generator set is connected to the stator through a bearing.

[0005] The present invention is also characterized in that

[0006] The siphon comprises a water inlet section, an ascending section, a hump section, a horizontal section and a descending section which are sequentially connected into one body, and the direct-drive generator set is installed in the horizontal section.

[0007] An inlet guide pipe and an outlet diffuser are also provided at the front and rear ends of the direct-drive generator set, and the inlet guide pipe and the outlet diffuser are located inside the siphon.

[0008] The inlet guide pipe comprises an inlet guide section and an inlet straight pipe section which are connected in sequence, and the inlet straight pipe section is connected to the inlet of the direct-drive generator set.

[0009] The outflow diffuser comprises an outflow straight pipe section and an outflow diffuser section which are connected in sequence, and the outflow straight pipe section is connected to the outlet of the direct-drive generator set.

[0010] The inlet of the water inlet section is bell-shaped, the length of the bell-shaped is 0.425D, the diameter of the inlet of the water inlet section is 2D, the diameter of other straight pipe sections of the siphon pipe is D, and the length of the horizontal section is not less than 1.2D.

[0011] The diameters of the outflow straight pipe section and the inflow straight pipe section are the same as the inner diameter of the runner, and the lengths are both 0.15D. The lengths of the center lines of the inflow guide pipe and the outflow diffuser are 0.5D and 0.4D respectively.

[0012] The inner diameter of the runner is 0.83D, the outer diameter is 0.9D, and the inner and outer diameters of the stator are 0.93D and D respectively.

[0013] Minimum wall thickness of siphon, inlet draft tube and outlet diffuser δ Should satisfy δ ≥ D / 130.

[0014] Installation angle of runner blades α Satisfaction: 5° ≤ α ≤20°, the distance between the blade tip and the runner center is less than 0.03D, the chord length of the airfoil at the blade tip is greater than 0.05D, and the chord length of the airfoil at the blade root is greater than 0.3D.

[0015] A one-way valve and a vacuum breaking valve are also provided on the hump section, and the one-way valve is connected to a vacuum pump.

[0016] The beneficial effects of the present invention are as follows: a direct-drive generator set is arranged in the horizontal section of the siphon pipe, the generator set is composed of a stator and a runner, the stator is fixedly mounted on the inner wall of the horizontal section, the runner and the stator are connected through bearings, and a rotating shaft does not need to be arranged in the center of the runner, thereby avoiding the sealing problem between the moving and static parts caused by the rotating shaft extending out of the siphon pipe; except for the inlet section of the siphon pipe being a bell-shaped one, the other sections are all circular straight pipes, and the ascending section and the horizontal section, and the horizontal section and the descending section are connected by a bent pipe, and the bending angles of the bent pipes are all less than 20°. The advantage of such a design is that the resistance along the siphon pipe is small; compared with the arc-shaped bend pipe, the straight pipe processing is simpler and more convenient, and the cost is also more advantageous. An inlet flow guide device and an outlet flow diffusion device are arranged before and after the direct-drive generator set, thereby improving the speed and stability of the water flow through the runner. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of a siphon type direct drive tubular turbine applicable to low head or ultra-low head of the present invention;

[0018] Figure 2 It is a structural schematic diagram of a direct-drive generator set in a siphon-type direct-drive tubular turbine applicable to low water head or ultra-low water head of the present invention;

[0019] Figure 3It is a three-dimensional structural schematic diagram of a runner of a direct-drive generator set in a siphon-type direct-drive tubular turbine applicable to low water head or ultra-low water head according to the present invention;

[0020] Figure 4 It is a schematic diagram of the excitation mode of a direct-drive generator set in a siphon-type direct-drive tubular turbine applicable to low head or ultra-low head of the present invention;

[0021] Figure 5 The present invention is a schematic structural diagram of an inlet flow guide and an outlet flow diffuser in a siphon type direct drive tubular turbine suitable for low head or ultra-low head.

[0022] In the figure, 1. siphon, 1-1. water inlet section, 1-2. rising section, 1-3. hump section, 1-4. horizontal section, 1-5. descending section, 2. vacuum breaking valve, 3. one-way valve, 4. inlet guide pipe, 4-1. inlet guide section, 4-2. inlet straight pipe section, 5. direct-drive generator set, 6. outflow diffuser, 6-1. outflow straight pipe section, 6-2. outflow diffuser section, 7. stator, 8. impeller, 9. permanent magnet. DETAILED DESCRIPTION

[0023] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] The present invention is applicable to a siphon type direct drive tubular turbine with low head or ultra-low head, and its structure is as follows: Figure 1 As shown, it includes a siphon tube 1, in which a direct-drive generator set 5 is installed, and a stator 7 of the direct-drive generator set 5 is fixedly installed on the inner wall of the siphon tube 1, as shown in FIG. Figure 2-4 As shown, the runner 8 of the direct-drive generator set 5 is connected to the stator 7 via a bearing.

[0025] The siphon 1 comprises a water inlet section 1-1, an ascending section 1-2, a hump section 1-3, a horizontal section 1-4 and a descending section 1-5 which are sequentially connected as one body, and a direct-drive generator set 5 is installed in the horizontal section 1-4.

[0026] An inlet guide pipe 4 and an outlet diffuser 6 are also provided at the front and rear ends of the direct-drive generator set 5 , and the inlet guide pipe 4 and the outlet diffuser 6 are located inside the siphon pipe 1 .

[0027] like Figure 5 As shown, the inlet guide pipe 4 includes an inlet guide section 4 - 1 and an inlet straight pipe section 4 - 2 which are connected in sequence, and the inlet straight pipe section 4 - 2 is connected to the inlet of the direct-drive generator set 5 .

[0028] The outflow diffuser 6 includes an outflow straight pipe section 6 - 1 and an outflow diffuser section 6 - 2 which are connected in sequence, and the outflow straight pipe section 6 - 1 is connected to the outlet of the direct-drive generator set 5 .

[0029] The entrance of the water inlet section 1-1 is bell-shaped, and the length of the bell-shaped is 0.425D to ensure that the submergence depth of the entrance should be greater than 1.5D. The diameter of the entrance of the water inlet section 1-1 is 2D, the diameter of the other straight pipe section of the siphon 1 is D, and the length of the horizontal section 1-4 is not less than 1.2D. This is to ensure that the water flow through the hump section is fully developed and to leave enough space for the installation of the generator set.

[0030] The diameters of the outflow straight pipe section 6-1 and the inflow straight pipe section 4-2 are the same as the inner diameter of the runner 8, and the lengths are both 0.15D. The lengths of the center lines of the inflow guide pipe 4 and the outflow diffuser 6 are 0.5D and 0.4D respectively.

[0031] The inner diameter of the runner 8 is 0.83D, and the outer diameter is 0.9D. The inner and outer diameters of the stator 7 are 0.93D and D respectively. The connection between the stator 7 and the horizontal section 1-4 of the siphon pipe is an interference fit, and the stator 7 and the runner 8 are connected through a bearing.

[0032] Minimum thickness of the walls of the siphon 1, the inlet guide tube 4 and the outlet diffuser 6 δ Should satisfy δ ≥ D / 130.

[0033] Installation angle of runner 8 blades α Satisfaction: 5° ≤ α ≤20°, the distance between the blade tip and the runner center is less than 0.03D, the chord length of the airfoil at the blade tip is greater than 0.05D, and the chord length of the airfoil at the blade root is greater than 0.3D.

[0034] A one-way valve 3 and a vacuum breaking valve 2 are also provided on the hump section 1 - 3 , and the one-way valve 3 is connected to a vacuum pump.

[0035] In order to facilitate the sealing and insulation of the direct-drive generator set 5, the overall structure of the unit 5 is arranged in a rotating magnetic field type, that is, the runner 8 is arranged inside the stator 7, and the runner 8 and the stator 7 are arranged as an inner rotor structure. The permanent magnet 9 is arranged at the rim of the runner 8 in an internal manner. A direct-drive generator set is adopted, and no rotating shaft is required to be set at the center of the runner, which solves the problem of difficult sealing at the point where the main shaft of the runner extends out of the siphon tube; the direct-drive generator set is completely arranged in the siphon tube, making the overall sealing of the siphon tube more convenient and feasible. The direct-drive generator set adopts an inner rotor arrangement structure, and the excitation method adopts permanent magnet excitation. The runner is directly connected to the generator set without additional mechanical transmission, forming a compact unit structure, which facilitates the compact arrangement of the overall structure of the present invention.

[0036] Different from the conventional cross-flow turbine which arranges the unit inside the dam, the present invention adopts the horizontal section 1-4 of the siphon tube to be installed above the dam, the inlet of the water intake section 1-1 is at the upstream water surface, and the outlet of the descending section 1-5 is located below the downstream water surface. The advantage of diverting water from above the dam is that earth excavation work and unnecessary plant construction are reduced. The installation, inspection and maintenance of the siphon tube and direct-drive generator set involved in the present invention are more convenient, which reduces the unit investment cost and operation cost of developing low-head or ultra-low-head hydraulic resources.

[0037] The present invention provides a vacuum breaker valve and a one-way valve at the highest point of the hump section of the siphon pipe. The vacuum breaker valve prevents the siphon pipe from being squeezed by the atmospheric pressure and destroyed when the pressure in the pipe is too low. When the unit needs to be shut down, the vacuum breaker valve is opened to allow air to flow into the siphon pipe, thereby destroying the vacuum and shutting down the unit. The one-way valve is used to connect the vacuum pump to discharge the air in the siphon pipe when the unit is started.

[0038] The ascending section and the horizontal section, and the horizontal section and the descending section of the siphon pipe of the present invention are connected by a bent pipe, and the turning angle of the bent pipe is θ Both are less than 20°, which can ensure that the siphon resistance coefficient is small.

[0039] The inlet flow guide device and the outlet flow diffuser arranged before and after the direct-drive generator set of the present invention accelerate the water flow at the runner in the horizontal section of the siphon pipe through the Venturi effect, and both the inlet flow guide device and the outlet flow diffuser are bent pipes.

[0040] The present invention is applicable to the working principle of the siphon type direct drive tubular turbine with low head or ultra-low head:

[0041] When the direct-drive generator set 5 is not started, a certain height difference is formed between the upstream and downstream water surfaces, and the inlet of the bell-shaped water inlet section 1-1 and the outlet of the descending section 1-5 are both submerged under the water surface. When the direct-drive generator set 5 needs to be started, the one-way valve 3 is connected to the vacuum pump to discharge the air in the siphon tube 1. As the air in the siphon tube 1 is gradually discharged, the water level in the tube gradually rises until the air in the hump section 1-3 of the siphon tube is completely discharged, and the hump section 1-3 forms a negative pressure. After the runner is completely submerged, the siphon effect and gravity cause the water in the tube to start flowing, pushing the direct-drive generator set 5 to start generating electricity. When the direct-drive generator set 5 needs to be shut down, the vacuum breaking valve 2 is opened, and air enters the tube to destroy the negative pressure of the hump section 1-3, the water flow stops flowing, and the direct-drive generator set 5 automatically shuts down. The function of the vacuum breaking valve 2 is also to prevent the negative pressure formed in the hump section 1-3 of the siphon tube from destroying the siphon tube 1 under the action of atmospheric pressure when the height difference between the upstream and downstream water surfaces is too large.

[0042] The present invention is suitable for siphon-type direct-drive tubular turbines with low or ultra-low water heads. A direct-drive generator set is arranged in the horizontal section of the siphon pipe. The runner and the stator are connected through bearings. No rotating shaft is required to be arranged at the center of the runner, thereby avoiding the sealing problem between the moving and static parts caused by the main shaft of the traditional siphon-type generator set passing through the siphon pipe. The inlet section of the siphon pipe is a bell-shaped type, and the submerged depth of the inlet should be greater than 1.5D to make the incoming flow as smooth as possible and reduce the surface vortex and submerged vortex at the inlet. The remaining sections of the siphon pipe are all circular straight pipes, and the bending angles of the curved bends connecting the ascending section, the descending section and the horizontal section are all less than 20°, so that the local resistance coefficient of the bend can be ensured to be small, so that the water flow flowing into the runner has a large flow rate and a stable flow state.

[0043] The present invention has the advantages of no civil construction, low cost, and convenient installation, maintenance and overhaul.

Claims

1. Suitable for siphon type direct drive tubular turbine with low or ultra-low water head, characterized in that: It comprises a siphon tube (1), a direct-drive generator set (5) is installed in the siphon tube (1), a stator (7) of the direct-drive generator set (5) is fixedly installed on the inner wall of the siphon tube (1), and a runner (8) of the direct-drive generator set (5) is connected to the stator (7) via a bearing; The siphon (1) comprises a water inlet section (1-1), an ascending section (1-2), a hump section (1-3), a horizontal section (1-4) and a descending section (1-5) which are sequentially connected into one body, and the direct-drive generator set (5) is installed in the horizontal section (1-4); The direct-drive generator set (5) is also provided with an inlet flow guide pipe (4) and an outlet flow diffuser (6) at the front and rear ends, and the inlet flow guide pipe (4) and the outlet flow diffuser (6) are located inside the siphon pipe (1); The inlet flow guide pipe (4) comprises an inlet flow guide section (4-1) and an inlet straight pipe section (4-2) which are connected in sequence, and the inlet straight pipe section (4-2) is connected to the inlet of the direct-drive generator set (5); The outflow diffuser (6) comprises an outflow straight pipe section (6-1) and an outflow diffuser section (6-2) which are connected in sequence, and the outflow straight pipe section (6-1) is connected to the outlet of the direct-drive generator set (5); The inlet of the water inlet section (1-1) is bell-shaped, the length of the bell-shaped is 0.425D, the diameter of the inlet of the water inlet section (1-1) is 2D, the diameter of the other straight pipe sections of the siphon (1) is D, and the length of the horizontal section (1-4) is not less than 1.2D; The diameters of the outflow straight pipe section (6-1) and the inflow straight pipe section (4-2) are both the same as the inner diameter of the runner (8), and their lengths are both 0.15D. The lengths of the center lines of the inflow guide pipe (4) and the outflow diffuser pipe (6) are 0.5D and 0.4D respectively.

2. The siphon type direct drive tubular turbine suitable for low head or ultra-low head according to claim 1, characterized in that: The inner diameter of the runner (8) is 0.83D, the outer diameter is 0.9D, the inner and outer diameters of the stator (7) are 0.93D and D respectively, and the blade installation angle of the runner (8) is α Satisfaction: 5° ≤ α ≤20°, the distance between the blade tip and the runner center is less than 0.03D, the chord length of the airfoil at the blade tip is greater than 0.05D, and the chord length of the airfoil at the blade root is greater than 0.3D.

3. The siphon type direct drive tubular turbine suitable for low head or ultra-low head according to claim 1, characterized in that: The minimum thickness of the walls of the siphon tube (1), the inlet flow guide tube (4) and the outlet flow diffuser tube (6) δ Should satisfy δ ≥ D / 130.

4. The siphon type direct drive tubular turbine suitable for low head or ultra-low head according to claim 1, characterized in that: The hump section (1-3) is also provided with a one-way valve (3) and a vacuum breaking valve (2), and the one-way valve (3) is connected to a vacuum pump.

Images