Analysis and Disposal of Oscillation Causes of Turbine with Transmission
Push Shower Valve,Push Button Shower Valve,Push Button Diverter,Push Pull Shower Faucet JANGMEN MOON SHOWER SANITARYWARE CO.,LTD , https://www.moonshowerglobal.comAnalysis and Disposal of Oscillation Causes of Turbine with Gearbox
The 2# steam turbine generator set of Xinjiang Steel Co., Ltd. is a 3MW unit system extraction steam condensing unit. The steam turbine is horizontally placed, with an island-type base at an elevation of +5.00m. It is a CN3-24/5 single-cylinder, extraction, and condensing unit produced by Hangzhou Steam Turbine Works. The high-pressure section consists of a double-column reheat stage and pressure stages, including a conditioning stage and six pressure stages. The front bearing is a tilting pad radial thrust combined spherical bearing installed in the front bearing seat, while the rear bearing is a tilting pad bearing integrated with the cylinder.
The turbine rotor is connected to the reduction pinion via a gear coupling, and a rigid coupling is used between the large gear and the generator. The generator is an air-cooled QF-K3-2 unit from Hangzhou Power Generation Equipment Factory. The unit has been operating for about 10 years without major overhauls in the last five years. During mid-November 2006, several issues were identified and addressed during maintenance.
One of the main problems was the oscillation of the tilting pad bearings. Unlike large units, the 1# and 2# bearing bushes consist of tilting pads—three on the bottom and two on the top. These pads are made of curved Babbitt material that can pivot freely around a fulcrum. This allows them to adjust dynamically based on speed, load, and oil film thickness, forming multiple oil wedges around the shaft. The lubricating oil enters through the gap between the pads and exits through the oil seal rings. If the friction forces and inertia are neglected, the oil film exerts a force that passes through the center of the shaft, ensuring radial stability and reducing the risk of oil film vibration.
Tilting pad bearings offer significant advantages, such as improved stability, higher bearing capacity, and better damping capabilities. However, their complex structure makes maintenance more challenging and costly. Despite this, they are increasingly used in high-power units due to their superior performance compared to three-oil wedge and cylindrical bearings.
During the maintenance process, it was found that the horizontal oscillation of the 2# bearing was caused by improper alignment between the pinion and the turbine coupling. After disassembling the gearbox and adjusting the coupling center, the oscillation was reduced. However, at critical speeds (~3000r/min), the oscillation reached 0.106mm, prompting further investigation.
Upon inspection, the clearance between the tilting pad and the shaft diameter on the lower right side of the 2# bearing was 0.16mm, while the left side had a clearance of only 0.04mm. Adjustments were made by adding a 0.10mm gasket to the back of the lower right tilting pad, which helped reduce the oscillation. Further fine-tuning led to a significant improvement in performance.
In addition, precise measurement and adjustment of the large gear were essential. Multiple skilled personnel conducted measurements to minimize errors. The parallelism and concave-convex values of the large gear were carefully adjusted, and the meshing gap was measured using dial indicators. Proper alignment ensured smooth operation and prevented future oscillation issues.
In conclusion, the proper installation, maintenance, and adjustment of turbine bearings and gearboxes are crucial for the safe and efficient operation of power generation units. Strict quality control and attention to detail during installation can prevent many common issues and ensure long-term reliability.
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This article is sourced from China Bearing Network. Please visit [http://www.chinabearing.net](http://www.chinabearing.net) for more information.
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