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Hydropower station turbine structure and assembly

August 26, 2020

Hydropower station turbine structure and assembly
1. Assembly of runner chamber, which includes runner chamber, base ring, and expansion joint.
1. The runner chamber is a steel plate welded structure. The upper part is made of stainless steel in the 90° cavitation-prone area within the blade rotation angle. The mating surface with the blade is a spherical surface. The throat diameter is Φ5277mm. In order to facilitate installation, it is divided into upper and lower halves. Put them together with bolts and use Φ14 rubber strips for sealing. The runner chamber is assembled with bolts and outer water guide ring, and the sealing flange is sealed with Φ16 rubber strip.
2. The base ring is equipped with an expansion joint, and the rear is welded to the draft tube. It is the expansion joint, the foundation of the runner chamber and the seat ring have certain coaxiality and parallelism requirements. The base ring adopts a steel plate welded structure. After the axis is installed and adjusted, the downstream end is welded firmly to the lining of the draft tube. The foundation ring has to withstand the hydraulic vibration from the runner chamber, so it is required to be firmly combined with the concrete.
3. The expansion joint is installed between the runner chamber and the base ring. The Φ27 rubber strip sealing structure can effectively prevent water leakage. The axial adjustment gap of the expansion joint is 15mm, which is used to eliminate the gap error during installation and also eliminate the cause The influence of plant foundation deformation on the unit structure.
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2. Seat ring assembly,
The seat ring assembly is divided into two parts: the seat ring and the downstream outer cone.
1. The seat ring is the main support of the unit. It bears most of the weight of the unit, water pressure, buoyancy, forward and reverse thrust, generator torque, etc., and transmits these loads to the foundation concrete, so it should have sufficient strength, Stiffness. The seat ring is the installation foundation of the entire unit. The water guide mechanism of the turbine, the generator stator, the combined bearing, etc. are all fixed on the flange and installed in sequence on this basis. The seat ring is divided into two halves of the inner ring and two halves of the outer ring. There are two fixed guide vanes in the horizontal direction and two entry tubes in the vertical direction. They are not only the main force-bearing member of the seat ring, but also the installation oil and water. , Gas pipeline and electrical circuit, replacement of hydraulic turbine guide bearing, seal, channel of combined bearing. Arrange some adjusting screws and anchors on the outer circle of the seat ring for installation and adjustment.
2. Water guide mechanism. The main function of the water guide mechanism of the bulb tubular unit is to generate water flow into the front ring of the runner, and adjust the flow according to the power of the unit. When the turbine stops running, the guide vanes are closed to cut off the water flow. The assembly of water guiding mechanism mainly includes: outer water distribution ring, inner water distribution ring, guide vane, control ring, pressure ring, sleeve, guide vane arm and transmission mechanism.
2.1 The outer water distribution ring is divided into two halves, and the joint surface between the two halves and the flange of the seat ring is sealed with an "O" rubber strip. The mating surfaces of the outer water distribution ring and the guide vanes are spherical, with a radius of SR3782mm. There are 16 guide vane sleeve holes on the outer water distribution ring, which form an angle of 65° with the centerline of the main shaft and are equally spaced. In order to measure the water pressure in the outer water distribution ring behind the guide vane, there are four G1/2 pressure measuring holes for connecting to the instrument. A limit block is welded on the outer water distribution ring to limit the maximum opening position of the guide vane.
2.2 The inner water distribution ring adopts a steel plate welded structure. The inner water distribution ring and the outer water distribution ring form a flow channel together, and the guide vane has a spherical radius SR1745mm. The spherical uniformly distributes 16 guide vane lower shaft holes, which are 65°clamped with the centerline of the main shaft. The angle has a fan-shaped plate at its lower part, which is the supporting part of the water guide bearing, and is provided with four G1/2 pressure measuring holes to measure the external water pressure of the inner water distribution ring behind the guide vane.
2.3 There are 16 guide vanes, the axis of which is 65° to the center line of the main shaft. The guide vane is the only component that forms the required annulus in front of the runner blade. The exit angle of each section is the same as the entrance angle of each section of the runner blade. Correspondingly, it has a space curved surface, and the rotation speed and power of the unit can be adjusted by adjusting the opening of the guide vane. When fully closed, the water flow can be cut off to stop the unit. The guide vanes are sealed by body metal contact. The upper bearing bush seal of the guide vanes is stacked with a stainless steel layer. The gap between the guide vanes and the inner and outer water distribution rings is 0.8-1.6mm, and the rotation angle of the guide vanes is 2°-78° , The total angle of rotation is 80°
2.4 The control ring is a two-half structure, which is connected by bolts, and 16 ear holes are evenly distributed on it. It forms a transmission mechanism with the connecting plate guide vane arm. The servomotor controls the rotation of the guide vane through the transmission mechanism. The control ring is installed on the outside of the flange on the downstream side of the outer water guide ring, and rolling friction is used with the outer water distribution ring to reduce friction. The groove is equipped with SΦ50mm steel balls and is lubricated with oil. On the horizontal center line of the control ring, there is another ear plate with a weight of 27t suspended. Normally, the guide vane is closed by operating it together with the servomotor. In the event of a governor accident, the guide vanes are closed by the closing torque formed by the weight of the hammer itself to ensure the safety of the unit.
2.5 The transmission mechanism is composed of a guide vane arm, a connecting rod, a control ring, and a guide vane as a spatial transmission system. When the guide vanes are stuck and cannot be closed, the connecting plate breaks the pin and the signal is automatically sent out