Stability of Centrifugal Compressors by Applications of Damper Seals

2011 ◽  
Author(s):  
Edmund A. Memmott
Keyword(s):  
Stability Analysis ◽  
Critical Frequency ◽  
Stable Operation ◽  
Test Results ◽  
Case Histories ◽  
Centrifugal Compressors ◽  
Full Load ◽  
Roughened Surface ◽  
Pressure Test ◽  
Full Pressure

This paper surveys the applications of damper seals to provide the stable operation with respect to rotordynamics of centrifugal compressors. Damper seals are applied as sealing devices at the division wall of back-to-back compressors and at the balance piston of in-line compressors. They consist of a roughened surface on the stator that is typically created by a pattern of holes. Rotordynamically stable operation is shown by a lack of or a small bounded amount of SSV (subsynchronous vibration) at the first fundamental lateral critical frequency. Experience plots showing the use of damper seals will be presented. Case histories of the use of damper seals will be given. Stability analysis and full load full pressure test results will be reviewed. The test results show no SSV at the first critical frequency with the damper seals.

New Steps to Improve Rotordynamic Stability Predictions of Centrifugal Compressors

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Manoj K. Gupta ◽  
Thomas A. Soulas ◽  
Dara W. Childs
Keyword(s):  
Centrifugal Compressor ◽  
Flow Model ◽  
Aerodynamic Performance ◽  
Magnetic Bearing ◽  
Point Of View ◽  
Test Results ◽  
Performance Point ◽  
Pressure Test ◽  
Full Pressure ◽  
Rotor Model

Improved rotordynamic stability is desired by end users, and centrifugal compressor manufacturers are expected to meet, if not exceed, this expectation. Compressor manufacturers are required to design and build machines that are rotordynamically stable on the test stand and in the field. Confidence has been established in predicting the excitation forces from seals and bearings, but impeller aerodynamic excitation forces continue to be a challenge. While much attention is paid to impellers from an aerodynamic performance point of view, more efforts are needed from a rotordynamic standpoint. A high-pressure, reinjection centrifugal compressor is analyzed in order to predict rotordynamic stability using the best available resources for seals and bearings. Impeller shroud forces are predicted using the bulk-flow model developed by Gupta and Childs (Gupta, M., and Childs, D., Proc. of ASME Turbo Expo 2000, Power for Land, Sea, and Air). Each impeller stage is analyzed and an attempt is made to improve the estimation of impeller aerodynamic excitation forces. Logarithmic decrement (log dec) predictions for the full rotor model consisting of all the stages and seals are compared to the full-load full-pressure test measured values using a magnetic bearing exciter. A good correlation is obtained between the measured test results and analytical predictions.

Using CFD to Improve Stall Margin

1999 ◽  
Author(s):  
James R. Hardin ◽  
Charles F. Boal
Keyword(s):  
High Efficiency ◽  
Industrial Applications ◽  
Stable Operation ◽  
Test Results ◽  
Peak Efficiency ◽  
Centrifugal Compressors ◽  
Stall Margin ◽  
Operating Range ◽  
Multi Stage ◽  
Cfd Analyses

Abstract Centrifugal compressors for multi-stage industrial applications must have both high efficiency and stable operation over a wide flow range. CFD analyses were used to evaluate the stall margins of candidate impeller designs compared to a baseline semi-inducer design. With this guidance, a new full-inducer impeller was designed with predicted wider operating range and slightly higher peak efficiency. Prototype tests confirmed these predictions. This paper presents predictions from two CFD codes and test results, for both the original and the redesigned impeller, and discusses the application of CFD for predicting impeller stall.

New Steps to Improve Rotordynamic Stability Predictions of Centrifugal Compressors

2007 ◽  
Author(s):  
Manoj K. Gupta ◽  
Thomas A. Soulas ◽  
Dara W. Childs
Keyword(s):  
Centrifugal Compressor ◽  
Flow Model ◽  
Aerodynamic Performance ◽  
Magnetic Bearing ◽  
Point Of View ◽  
Test Results ◽  
Performance Point ◽  
Pressure Test ◽  
Full Pressure ◽  
Rotor Model

Improved rotordynamic stability is desired by end users, and centrifugal compressor manufacturers are expected to meet, if not exceed, this expectation. Compressor manufacturers are required to design and build machines that are rotordynamically stable on the test stand and in the field. Confidence has been established in predicting the excitation forces from seals and bearings, but impeller aerodynamic excitation forces continue to be a challenge. While much attention is paid to impellers from an aerodynamic performance point of view, more efforts are needed from a rotordynamic standpoint. A high-pressure, re-injection centrifugal compressor is analyzed in order to predict rotordynamic stability using the best available resources for seals and bearings. Impeller shroud forces are predicted using the bulk-flow model developed by Gupta and Childs [1]. Each impeller stage is analyzed and an attempt is made to improve the estimation of impeller aerodynamic excitation forces. Logarithmic decrement (log dec) predictions for the full rotor model consisting of all the stages and seals are compared to the full-load full-pressure test measured values using a magnetic bearing exciter. A good correlation is obtained between the measured test results and analytical predictions.

scholarly journals A Bus-Sectionalized Hybrid AC/DC Microgrid: Concept, Control Paradigm, and Implementation

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3508
Author(s):  
Jing Li ◽  
Hongda Cai ◽  
Pengcheng Yang ◽  
Wei Wei
Keyword(s):  
Hierarchical Control ◽  
Mode Switching ◽  
Stable Operation ◽  
Service Reliability ◽  
Test Results ◽  
Dc Microgrid ◽  
Dc Microgrids ◽  
Operation Modes ◽  
Control Paradigm ◽  
Operational Data

In the last several years, the coordination control of hybrid AC/DC microgrids (HMGs) has been gaining increasingly more attention. However, most of these discussions are focused on single-bus HMGs whose AC or DC bus is not sectionalized by AC or DC breakers. Compared with these single-bus HMGs, the bus-sectionalized HMG has more flexible topologies, more diverse operation modes, and consequently higher service reliability. However, meanwhile, these benefits also bring challenges to the stable operation of bus-sectionalized HMGs, particularly for mode switching. Relying on the national HMG demonstrative project in Shaoxing, China, this paper makes efforts to present the hierarchical control paradigm of a typical bus-sectionalized HMG toward standardization. The test results demonstrate that the proposed system provides seamless switching and uninterrupted power supply without controller reconfiguration among different operation modes. The operational data are also brought forth and analyzed to provide significant and useful experiences for designing and developing similar HMGs in the future.

Upgrading of Tubular Heat Exchangers by the Helical Spacer Method and Evaluation

2002 ◽  
Author(s):  
F. L. Eisinger ◽  
R. E. Sullivan
Keyword(s):  
Theoretical Analysis ◽  
Acoustic Wave ◽  
Heat Exchangers ◽  
Test Results ◽  
Vibration Testing ◽  
Safe Operation ◽  
Shell Side ◽  
Full Load ◽  
Post Modification ◽  
Side Flow

The tubular heat exchangers described exhibited a sensitivity to flow-induced tube vibration at about 50% of their design shell-side flow. Following a detailed theoretical analysis, the heat exchangers were modified by the helical spacer method providing additional tube supports in-between the existing support plates and in the U-bend. This modification aimed at allowing the heat exchangers to operate safely and reliably at full load, including a 25% overload. Post modification sound and vibration testing was performed which confirmed the adequacy of the modification. The test results showed however, that at the overload condition, an unusual acoustic wave inside the shell was developing. It was determined that this wave would not be harmful to the safe operation of the heat exchangers. The paper will discuss the findings in more detail.

Experiment and Dynamic Simulation of PIG Motion during Pigging Operation in a Slope Pipeline

2018 ◽  
Vol 16 (9) ◽  
Author(s):  
Jun Zhou ◽  
Tao Deng ◽  
Guangchuan Liang ◽  
Jinghong Peng ◽  
Tian Meng ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Water Pressure ◽  
Oil And Gas Industry ◽  
Unsteady Motion ◽  
Stable Operation ◽  
Two Phase ◽  
Transient Model ◽  
Water Pressure Test ◽  
Pressure Test ◽  
Hydraulic Pulse

Abstract Pigging techniques are widely used in the oil and gas industry. The unsteady motion of the PIG in an undulating pipe section during the pigging process after a water pressure test affects the stable operation of the pipeline and also causes a pipe rupture accident in serious cases. First, an experimental study was conducted to investigate the pigging process of air–water two phase pipe flows, and the PIG reverse movement and hydraulic pulse phenomenon were observed. Subsequently, a hydraulic transient model of the pigging process after a water pressure test was established in a dual-grid system. The model combined mass and motion equations of gas and liquid and PIG dynamic equations, considered three types of PIG motion states, namely positive movement, reverse movement and still, and used the method of characteristics to solve the equations. The model exhibits the ability for PIG tracing and hydraulic pulse prediction. It can be used to obtain the position and speed of the PIG. Finally, the field data and simulation results were compared, and the results indicated that they are essentially identical. This verified the accuracy of the model that is established in this study and the reliability of computed results and provided a reliable and effective theoretical basis for the development of field pigging plans.

Study on Conventional Domed Bursting Disc Material and Burst Pressure Test

2013 ◽  
Vol 690-693 ◽  
pp. 2371-2378
Author(s):  
Wei Pu Xu ◽  
Yi Ting Liu
Keyword(s):  
Stainless Steel ◽  
Tensile Test ◽  
316L Stainless Steel ◽  
Performance Test ◽  
Test Method ◽  
Burst Pressure ◽  
Test Results ◽  
Manufacturing Method ◽  
Pressure Test ◽  
Disc Material

A brief overview is given in the conventional domed bursting disc structure and manufacturing method. 316L stainless steel as a template is selected. With the investigation on bursting disc material tensile test method, the test results are summarized,also the burst results of disc burst pressure in different sizes. With the help of bursting disc material performance test and bursting disc burst pressure test of 316L , the test results provide a reference for other types of bursting disc.

On Instability of Overhung Centrifugal Compressors

1999 ◽  
Author(s):  
François Berot ◽  
Hervé Dourlens
Keyword(s):  
Thermal Effect ◽  
Dynamic Behavior ◽  
Numerical Study ◽  
Technical Solution ◽  
Test Results ◽  
Centrifugal Compressors ◽  
The Third ◽  
Instability Problem ◽  
Angle Rotation ◽  
Bearing Design

This paper describes the synchronous vibration instability problem that occurred on a series of large overhung centrifugal compressors. The first part of this paper deals with the identification and display of the instability phenomenon: cyclic vibration amplitude variations and phase angle rotation occuring during testing of overhung centrifugal compressors. After numerical simulations and analysis of the test results, the bearing design has been identified as the cause of the problem. The second part describes the numerical study of the instability of the compressor. This problem is related to the eccentricity of the shaft in the bearing and to the shape of its orbit. We have investigated and propose different solutions to avoid this unstable dynamic behavior. These solutions have been tested on different compressors and have confirmed the results of the numerical analysis. The third part reminds a link between the thermal effect occurring in the bearings, the numerical results and the tested dynamic behavior of the compressor. Recently, some authors such as Keogh et al. (1994) and Liebich et al. (1994) have noticed and studied this unstable behavior. Althougth the nature of the phenomenon seems to be known (de Jongh et al., 1984) (Faulkner et al., 1997a, 1997b), no universal technical solution to this important problem has been found. The contribution of this work is to present another case of the influence of the thermal effect on the dynamic behavior of an overhung compressor. We present the typical symptoms of the phenomenon, explain it, and propose the solutions we have used to avoid the problem.

CFD Assessment of Rotordynamic Coefficients in Labyrinth Seals

2014 ◽  
Author(s):  
Sai S. Sreedharan ◽  
Giuseppe Vannini ◽  
Hiteshkumar Mistry
Keyword(s):  
High Speed ◽  
Test Results ◽  
Active Magnetic Bearings ◽  
Test Rig ◽  
Labyrinth Seals ◽  
Cfd Simulations ◽  
Flow Solver ◽  
Rotordynamic Coefficients ◽  
Pressure Test ◽  
Dynamic Seal

Seals used in high speed centrifugal compressors are prone to generate rotordynamic (RD) instabilities. To further understand their influence, a CFD based approach is developed. The objective of the current study is to numerically investigate and characterize the RD coefficients, representative of the dynamic seal forces. Experiments were carried out at high pressure test rig (up to 200 bar seal inlet pressure) which runs at 10000 RPM and has a high pre-swirl (about 0.9) along the same direction of rotor rotation. The rotor shaft in the experiment was instrumented with active magnetic bearings (AMBs) to linearly excite the rotor at three different frequencies: 28 Hz, 70 Hz and 126 Hz. Each frequency is characterized by amplitude of vibration and a phase. CFD simulations were carried out using commercial flow solver, using similar boundary conditions as that of experiments. The paper describes details of CFD model and its comparison against experiments. Numerical results show reasonable agreement of RD coefficients with test results. This job has to be considered as a first approach to CFD methodology applied to annular seals for the authors.

Study on Combustor Outlet Temperature Field of Gas Turbine

2011 ◽  
Vol 138-139 ◽  
pp. 962-966 ◽  
Author(s):  
Kai Liu ◽  
Li Xu
Keyword(s):  
Experimental Study ◽  
Temperature Field ◽  
Gas Turbine ◽  
Reference Value ◽  
Test System ◽  
Outlet Temperature ◽  
Test Results ◽  
Heavy Duty ◽  
Pressure Test ◽  
Heavy Duty Gas Turbine

Experimental study on combustor outlet temperature field of heavy-duty gas turbine had been finished on high-pressure test system. Experimental results indicate: The OTDF is sensitive to diameter of dilution holes, and the RTDF is sensitive to location of dilution holes. The test results have important guiding significance and reference value to design, commission and working about the similar combustor.

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