Paper 7: Design of a Range of Condensing Steam Turbines for the Petrochemical Industry

Author(s):  
D. Whitehouse ◽  
A. J. A. Schoenmakers ◽  
T. J. Goldsmith

To meet the requirements of the industry for condensing turbines capable of high speeds, the turbines need to be specifically designed for the purpose. The authors deal with straight condensing turbines, and show the powers, speeds, and steam conditions which are required. A range of turbines is set down covering speeds up to 20 000 rev/min and powers up to 15 000 hp. A 12 000 rev/min turbine is illustrated, and some design aspects are discussed in more detail. Particular reference is made to the design of the h.p. and l.p. blading, the rotor system, and the governor system.

Author(s):  
Lin Gao ◽  
Yiping Dai ◽  
Zhiqiang Wang ◽  
Yatao Xu ◽  
Qingzhong Ma

At present, the majority of power steam turbines operate under part-load conditions during most of their working time in accordance with the fluctuation of power supply. The load governing method may cause partial admission in control stage and even some pressure stages, which impacts much on the stability of the rotor system. In this paper, CFD and FEM method were used to analyze the effect of partial admission on rotor system stability. A new approach is proposed to simplify the 3D fluid model for a partial admission control stage. Rotordynamic analysis was carried out to test the stability of the HP rotor of a 600 MW steam turbine under different load conditions. 13 different governing modes on the rotor stability were conducted and data were analyzed. It is found that rotor stability varies significantly with different governing modes and mass flow rates, which is consistent with the operation. Asymmetric fluid forces resulted from partial admission cause a fluctuation of the dynamic characteristics of the HP bearings, which consequently affect the stability of the rotor system. One of the nozzle governing modes in which the diagonal valves open firstly is demonstrated as the optimal mode with the maximum system stability. The optimization has been applied to 16 power generation units in China and result in improved rotor stabilities.


1998 ◽  
Vol 120 (1) ◽  
pp. 87-94 ◽  
Author(s):  
Chong-Won Lee ◽  
Sang-Bok Chun

An assumed modes method is developed to investigate the effect of multiple flexible disks on the vibrational modes of a flexible rotor system. The analysis rotor model consists of multiple disks on a flexible shaft, as used for steam turbines or computer storage devices. In modeling the system, centrifugal stiffening and disk flexibility effects are taken into account. To demonstrate the effectiveness of the method, a hard disk drive spindle system commonly used in personal computers and a simple flexible rotor system with two disks are selected as examples. In particular, the dynamic coupling between the vibrational modes of the shaft and the duplicate disks is investigated with the shaft rotational speed varied.


A study has been made of the deformation at high strain rates of solids under the impact of liquids. A method is described for projecting a short liquid jet against a solid surface at speeds up to 1200 m/s. The flow of the liquid and the deformation of the solid during impact have been examined by high speed photographic methods. An attempt has been made to measure the magnitude and duration of the load by means of a piezoelectric pressure transducer. There is evidence that the liquid behaves initially on impact in a compressible manner. Part of the deformation of the solid is due to this compressible behaviour and part to the erosive shearing action of the liquid flowing at very high speeds out across the surface. The mode of deformation in brittle and in plastically deforming materials has been investigated. The deformation patterns produced are shown to be characteristic of liquid impact. The predominating mechanism of deformation depends on the mechanical properties of the solid and on the velocity of impact.


Author(s):  
Bugra H. Ertas ◽  
Massimo Camatti ◽  
Gabriele Mariotti

One type of test performed for evaluating bearings for application into turbomachinery is the synchronous bearing response to rotor imbalance. This paper presents rotordynamic tests on a rotor system using a 70mm diameter damped gas bearing reaching ultra-high speeds of 50,000 rpm. The main objective of the study was to experimentally evaluate the ability of the damped gas bearing to withstand large rotor excursions and provide adequate damping through critical speed transitions. Two critical speeds were excited through varying amounts and configurations of rotor imbalance, while measuring synchronous rotordynamic response at two different axial locations. The results indicated a well-damped rotor system and demonstrated the ability of the gas bearing to safely withstand rotor vibration levels while subjected to severe imbalance loading. Also, a waterfall plot was used to verify ultra high-speed stability of the rotor system throughout the speed range of the test vehicle. In addition to the experimental tests, a rotordynamic computer model was developed for the rotor-bearing system. Using the amplitude/frequency dependent stiffness and damping coefficients for the ball bearing support and the damped gas-bearing support, a pseudo-nonlinear rotordynamic response to imbalance was performed and compared to the experiments.


Author(s):  
Bugra H. Ertas ◽  
Massimo Camatti ◽  
Gabriele Mariotti

One type of test performed for evaluating bearings for application into turbomachinery is the synchronous bearing response to rotor imbalance. This paper presents rotordynamic tests on a rotor system using a 70 mm diameter damped gas bearing reaching ultra-high speeds of 50,000 rpm. The main objective of the study was to experimentally evaluate the ability of the damped gas bearing to withstand large rotor excursions and provide adequate damping through critical speed transitions. Two critical speeds were excited through varying amounts and configurations of rotor imbalance while measuring the synchronous rotordynamic response at two different axial locations. The results indicated a well-damped rotor system and demonstrated the ability of the gas bearing to safely withstand rotor vibration levels while subjected to severe imbalance loading. Also, a waterfall plot was used to verify ultra-high-speed stability of the rotor system throughout the speed range of the test vehicle. In addition to the experimental tests, a rotordynamic computer model was developed for the rotor-bearing system. Using the amplitude/frequency dependent stiffness and damping coefficients for the ball bearing support and the damped gas-bearing support, a pseudononlinear rotordynamic response to imbalance was performed and compared with the experiments.


2003 ◽  
Author(s):  
Catherine M. Burns ◽  
Lisa Garrison ◽  
Nick Dinadis

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