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Hydropower Station Turbine Structure and Assembly Ⅱ

August 28, 2020

Three, runner assembly

 

The runner is an important part of a water turbine, which converts the energy of the water flow into mechanical energy. The main shaft is transferred to the generator and converted into electrical energy. The runner model is GZ4BN28A. The runner assembly includes blades, runner core, piston cylinder, and blade drive mechanism. The nominal diameter of the runner is 5.5 meters, the cylinder-acting structure, the hub ratio is 0.36, the working oil pressure is 6.0Mpa, four blades, the blades can be adjusted to the best position according to the head and load to ensure that the turbine runs under high efficiency conditions .
1. The runner body is spherical in the range of the blade rotation angle. There are four holes on the outer wall of the spherical surface with a diameter of Φ1980mm. The inner copper bushing is the external bearing of the blade system. The runner body is provided with an oil drain valve and a vent hole for It is used for oil discharge, oil filling and exhaust during installation, test and maintenance. The runner body and the main shaft flange are combined with 12 M100х4 double-end studs, and 4 φ140 cylindrical pins are provided to transmit torque.
2. It is connected to the runner body with 12 M64X4 studs, and is equipped with 4 φ100 cylindrical pins to transmit torque. The runner body is equipped with four holes on all sides, and the copper sleeve and the four on the runner body are installed. The two holes form the inner and outer supports of the blade shaft, and there is a φ160 through hole in the middle for installing the operating oil pipe. ?? 3. It has a pivotless structure. It is combined with the rotating arm with 7 M90 connecting bolts, and 2 Φ90 cylindrical pins transmit torque. The sealing form of the blade flange adopts "V" and "X" rubber combined seals. It can effectively ensure no oil leakage and no water seepage. The blade material is ZGOCr13Ni6Mo, which has good wear resistance and cavitation resistance.
4. Composed of servomotor cylinder, piston, rotating arm, connecting rod, etc., adopting a cylinder-moving structure, the piston is fixed, and the pressure oil from the oil receiver switch chamber moves through the servomotor cylinder to drive the connecting rod and rotating arm The operating blade rotates. Two guide keys are provided at the matching parts of the servomotor cylinder and the guide cylinder to prevent the piston cylinder from rotating. There is a good seal between the piston and the piston cylinder, which can effectively reduce the oil leakage of the two chambers. The piston diameter is 990mm and the operating oil pressure is 6.0Mpa.

Fourth, spindle assembly
1. Main shaft, this unit is a main shaft, the diameter of the shaft body is Φ898mm, the matching diameters of the water guide bearing are Φ900mm and Φ950mm respectively, the shaft length is 6517mm, the shaft inner diameter is Φ160mm, the flange diameter of the runner end is Φ1640mm, and the generator rotor end The flange is Φ1550mm, the flanges at both ends are connected with the runner and the rotor by bolts, and there are pins to transmit torque.
2. Coupling screw guard. The guard is divided into two halves. It is sealed with sealing strips on the end face and radial direction of the flange of the large shaft. The role of the guard is to prevent the bolts between the runner body and the main shaft from being bubbled In water, avoid underwater fatigue damage of bolts.

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Fifth. Water guide bearing device

The hydraulic turbine guide bearing adopts dynamic and static pressure combined oil film bearing, and the bearing bush is made of tin-based alloy material, divided into half structure, inner diameter Φ900mm, bush length 685mm, total clearance of 0.6-0.78mm. When the turbine speed exceeds 95% of the rated speed, the bearing operates under dynamic pressure. At this time, the bearing oil film is formed by dynamic pressure. The lubricating oil comes from a gravity tank. Use HU-46 turbine oil. The drained oil flows to the hydraulic pump station located in the turbine pit. When the turbine starts and the unit stops, when the speed is lower than 95% of the rated speed, the bearing operates under static pressure. At this time, the high-pressure oil supplied by the high-pressure oil pump is passed to the high-pressure inlet cavity under the bearing bush, and the main shaft is jacked up with high-pressure oil. Oil film, to avoid the oil film rupture at low speed and cause the bearing bush to burn out.
Considering the weight of the turbine runner and generator rotor, the main shaft is bent. In addition to the unilateral magnetic pulling force of the generator during the operation of the unit, the main shaft will continuously change the deflection value and use its deformation direction, so the bearing adopts a self-aligning structure, so that the bearing bush can be adjusted accordingly with the main shaft.
There is a resistance water thermometer at the bottom of the bearing bush, which can both read and send a signal. When the bearing bush temperature reaches 70°C, it will send a signal to instruct the unit to stop accidentally.