Experimental Study on Fault Caused by Partial Arc Steam Forces and Its Economic Solution

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Daren Yu ◽  
Yanfeng Duan ◽  
Jinfu Liu ◽  
Zhansheng Liu ◽  
Qinghua Hu
Keyword(s):  
Experimental Study ◽  
Temperature Rise ◽  
Mechanism Analysis ◽  
Steam Turbines ◽  
Practical Test ◽  
Full Load ◽  
Control Stage ◽  
Fault Mechanism ◽  
Fault Characteristic

It is noticed in a few steam turbines that there are a pad temperature rise of more than 10°C and a radial journal movement of more than 50 μm in the bearings adjacent to control stage when they operate under partial arc admission at 60–80% of their full load. It is found through fault mechanism analysis and experimental study that the fault is caused by partial arc steam forces acting on control stage. A fault characteristic is concluded to help identify this fault. Diagonal admission is therefore proposed as an economic solution for elimination of this fault and it is proved to be effective through practical test.

Suppression of Subsynchronous Vibrations in a 11 MW Steam Turbine Using Integral Squeeze Film Damper Technology at the Exhaust Side Bearing

2016 ◽  
Author(s):  
Riccardo Ferraro ◽  
Michael Catanzaro ◽  
Jongsoo Kim ◽  
Michela Massini ◽  
Davide Betti ◽  
...  
Keyword(s):  
Steam Turbine ◽  
Labyrinth Seal ◽  
Squeeze Film ◽  
Stable Operation ◽  
Steam Turbines ◽  
Squeeze Film Damper ◽  
Full Load ◽  
Steam Admission ◽  
Before And After ◽  
Full Speed

The presence of high subsynchronous vibrations and other rotordynamic instabilities in steam turbines can prevent operation at full speed and/or full load. The destabilizing forces generating subsynchronous vibrations can be derived from bearings, seals, impellers or other aerodynamic sources. The present paper describes the case of an 11 MW steam turbine, driving a syngas centrifugal compressor train, affected by subsynchronous vibrations at full load. After the occurrence of anomalous vibrations at high load and a machine trip due to the high vibrations, the analysis of data collected at the site confirmed instability of the first lateral mode. Further calculations identified that the labyrinth seal at the balance drum was the main source of destabilizing effects, due to the high pre-swirl and the relatively tight seal clearance. The particular layout of the turbine, a passing-through machine with a combined journal/double thrust bearing on the steam admission side, together with the need for a fast and reliable corrective action limited the possible solutions. Based on the analyses performed, adjusting the clearance and preload of the journal bearings could not have ensured stable operation at each operating condition. The use of swirl brakes to reduce the steam pre-swirl at the recovery seal entrance would have required a lengthy overhaul of the unit and significant labor to access and modify the parts. The final choice was a drop-in replacement of only the rear bearing (on the steam exhaust side) with a bearing featuring integral squeeze film damper (ISFD) technology. In addition to being a time efficient solution, the ISFD technology ensured an effective tuning of stiffness and damping, as proven by the field results. The analyses carried out to understand the source of the subsynchronous vibrations and to identify possible corrective actions, as well as the comparison of rotordynamic data before and after the application of the bearing with ISFD technology, are discussed.

Failure Process and Mechanism Analysis for the Connecting Rod of Diesel Engine

2012 ◽  
Vol 463-464 ◽  
pp. 1597-1600
Author(s):  
Ying Kui Gu ◽  
Kang Hu ◽  
Jing Li
Keyword(s):  
Diesel Engine ◽  
Material Properties ◽  
Treatment Process ◽  
Failure Process ◽  
Organization Structure ◽  
Scientific Basis ◽  
Mechanism Analysis ◽  
Connecting Rod ◽  
Fault Mechanism ◽  
Physical And Chemical

The operational fault of diesel engine caused by losing the required function in running is a random phenomenon. It needs to collect a large number of fault samples and reliability data to reveal the fault occurrence rule and describe it with mathematical method. In this paper, the fault law and mechanism of the engine connecting rod were researched by the physical and chemical analysis of the fault samples. The fault reasons and the fault mechanism can be found through the analysis of the organization structure, material properties, process features, heat treatment process and other reliability information of the fault sample. It can provide scientific basis for the failure exclusion as well as the optimization and improvement of connecting rod structure.

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