Shenyang Getai Hydropower Equipment Co., Ltd.

Factors Affecting End Gap Of Guide Vane

Nov. 28, 2019

The energy conversion process of a hydro-generator set is divided into two stages: first, the potential energy lost by the water is converted into mechanical energy by the water turbine, and then the mechanical energy of the water turbine is converted into electrical energy by the generator. The specific process is: under the impact of the water flow, the water turbine starts to rotate, converting the water's potential energy into mechanical energy; the water turbine drives the coaxially connected generator to rotate. Under the action of the exciting current, the rotating rotor drives the exciting magnetic field to rotate. The stator windings of the generator cut the exciting magnetic field lines to generate an induced electromotive force, which will generate an electromagnetic braking torque on the rotor that is opposite to the direction of rotation while outputting electrical energy. . Since the water flow acts on the turbine uninterruptedly, the rotating torque obtained by the water turbine is used to overcome the electromagnetic braking torque generated on the motor rotor. When the two torques reach equilibrium, the hydroelectric generator set will run at a constant speed , Stably emits electricity, and realizes energy conversion. Therefore, the hydraulic turbine and generator are the two most critical components in a hydroelectric generating set.


Casting Guide Vane


Casting Guide Vane


The guide vane is one of the most important castings and forgings in the water guide mechanism of a hydro-generator set, and its manufacture has always been a major problem in the manufacture of large hydro-turbine units. In the past, guide vanes were mostly produced by sand casting. The quality of Casting Guide Vane was unstable, and it was easy to produce common casting defects such as shrinkage, shrinkage, pores, inclusions, and cracks. However, the control of the end face clearance of the guide vane is important for the flexible rotation of the guide vane, and the small leakage when the guide vane is closed is important. The total clearance of the ALSTOM unit of the Three Gorges Left Bank Power Station is 1.5 ~ 2.5mm. ~ 0.7mm, the upper clearance is not less than 1.0mm. The clearance is guaranteed by the thickness control of 186 permanent spacers between the top cover and the seat ring. So what are the factors that affect the end gap of the guide vanes? Pelton Turbine suppliers will come and tell everyone.


There are many factors that affect the end surface clearance, mainly the temperature, the tension of the cap / seat ring handle bolts, and the effect of the top deflection after the guide vanes. Before the top cover is pre-installed, first check the height and level of the bottom ring, especially the bottom ring level, and the height difference between the highest point and the lowest point on the bottom ring must not exceed 0.2mm (measured at 24 guide vane holes). Measure the length of the guide leaf body. Since there is not a long enough micrometer on the outside of the site, our measurement method is to use two rigid rulers to draw out from the two ends of the guide vane on the same side of the guide vane shaft, and use the inner micrometer to measure the distance between rulers. Leaf body length. In order to reduce the measurement error, use gasoline or acetone to clean off the oily impurities at the ends, and use sandpaper to polish off the burrs and high points on the edges; two rulers should be drawn from the corresponding parts at both ends to prevent large deviations in the measurement data; The length of the ruler should not be too long. It is better to use an internal micrometer to measure it. This can avoid errors caused by poor parallelism of the two ends; The surface of the bottom ring is a finished surface. After repeated local repair welding and polishing, the surface of the anti-wear plate of the bottom ring is uneven, which seriously affects the measurement and adjustment of the installation level of the bottom ring. In view of the deformation of the bottom ring, the bottom ring anti-wear plate is returned to the factory for processing 0.30 mm. In order to meet the installation size requirements, a ring groove is processed on the bottom ring anti-wear plate, and an elastic seal is installed to compensate the processing amount. Compensation is made; the end gap is adjusted according to the manufacturer's design lower limit, and the end gap is adjusted according to the lower limit required by the design drawing. At the same time, the guide vanes that affect the end gap are ground, pre-installed, and the entire lower pad of the sleeve is integrated. replace. After the bottom ring is assembled, the horizontal measurement is performed. The measurement surface of the bottom ring meets the requirements. The parallelism deviation between the top cover and the bottom ring is within 0.05 mm / m, which meets the requirements of the installation technical specifications, and the deviation of the end face gap becomes smaller.


The above is the influencing factors and treatment of the guide vane end face gap shared by Hydraulic Turbine Generator Supplier. Hope to help you.

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