Evaluating Vibration Performance of a Subsea Pump Module by Full-Scale Testing and Numerical Modelling

Author(s):  
Pieter J. G. van Beek ◽  
Hajo P. Pereboom ◽  
Harmen J. Slot

Prior to subsea installation, a subsea system has to be tested to verify whether it performs in accordance with specifications and component specific performance evaluation criteria. It is important to verify that the assembled components work in accordance with the assumptions and design criteria used in the detailed engineering. These criteria also cover the vibration performance. In the current study, the pump module within the Åsgard subsea compression station has been subjected to such system evaluation test, including its vibration performance. Vibrations may be caused by internal and external flow through a complex process that is affected by numerous factors such as the piping geometry, flow and operating conditions and also the fluid properties. When severe, mechanical vibrations can lead to fatigue failure of the equipment components. One of the major parameters that affects the vibration response of the subsea piping is the surrounding water. It is generally known that surrounding water does participate in some vibration modes by adding mass to the total, dynamic mass participating in the vibration. Therefore, resonant frequencies of a piping system will have different values for non-submerged and submerged cases. In addition, the surrounding water can also lead to higher damping of the vibration modes. In this paper the effect of submerging a pipe system in water is quantified, by analyzing the changes in damping coefficient and the characteristics of measured pipe vibration in-situ. This is achieved by analysis of full-scale frequency response tests performed on a subsea pipe system within the pump module in both non-submerged and submerged conditions. The results are used for validation of numerical techniques that are used to quantify pipe vibration in submerged conditions. Different modeling techniques for the submerged case are investigated. It is shown that the effects from the surrounding water on pipe vibrations are different for small-bore piping than that for main piping. Furthermore the different modeling approaches and general observations and trends in damping coefficients are discussed and compared with the measurements.

Author(s):  
Hugh Goyder

A full scale pipework system, typical of oil and gas installations located on the sea floor, was subjected to vibration tests in both dry and submerged conditions. The frequency range examined covered 10 Hz to 500 Hz. The objective of the tests was to provide experimental data so that computer simulations could be developed and validated. The method used to determine the vibration properties was that of an experimental modal analysis using an impact hammer. The hammer was modified for underwater use. In dry conditions the damping was found to be very small (damping ratio less than 0.0002) despite the construction being typical. When submerged the effect of the surrounding water was significant. The changes in the natural frequencies from the dry case to the wet case occurred in such a complex manner that it was not possible to identify a simple shift between wet and dry vibration modes. It was necessary to include appropriate added mass coefficients in the computer simulation for both the pipe and the support system. The effect of the surrounding water on the damping was measured but found to be insignificant. It was concluded that immersion in water does not add significant damping to oil and gas pipework.


1993 ◽  
Vol 21 (1) ◽  
pp. 23-39 ◽  
Author(s):  
R. W. Scavuzzo ◽  
T. R. Richards ◽  
L. T. Charek

Abstract Tire vibration modes are known to play a key role in vehicle ride, for applications ranging from passenger cars to earthmover equipment. Inputs to the tire such as discrete impacts (harshness), rough road surfaces, tire nonuniformities, and tread patterns can potentially excite tire vibration modes. Many parameters affect the frequency of tire vibration modes: tire size, tire construction, inflation pressure, and operating conditions such as speed, load, and temperature. This paper discusses the influence of these parameters on tire vibration modes and describes how these tire modes influence vehicle ride quality. Results from both finite element modeling and modal testing are discussed.


1989 ◽  
Vol 21 (10-11) ◽  
pp. 1389-1402 ◽  
Author(s):  
R. Zaloum

Deviations from design expectations appear to stem from views which assume that a unique response should result from a given set of operating conditions. The results of this study showed that two systems operating at equal organic loads or F/M ratios and at the same SRT do not necessarily give equal responses. This deviation was linked to the manner in which the HRT and influent COD are manipulated to obtain a constant or uniform load, and to subtle interactions between influent COD, HRT and SRT on the biomass and effluent responses. Increases of up to 200% in influent COD from one steady level to the next did not significantly influence the effluent VSS concentration while an effect on filtered COD was observed for increases as low as 20%. Effluent TKN and filtered COD correlated strongly with the operating MLVSS while phosphorus residual depended on the operating SRT and the organic load removed. These results point to the inadequacy of traditional models to predict effluent quality and point to the need to consider these effects when developing simulation techniques or computer assisted expert systems for the control of waste treatment plants.


Author(s):  
Brian Hollon ◽  
Erlendur Steinthorsson ◽  
Adel Mansour ◽  
Vincent McDonell ◽  
Howard Lee

This paper discusses the development and testing of a full-scale micro-mixing lean-premix injector for hydrogen and syngas fuels that demonstrated ultra-low emissions and stable operation without flashback for high-hydrogen fuels at representative full-scale operating conditions. The injector was fabricated using Macrolamination technology, which is a process by which injectors are manufactured from bonded layers. The injector utilizes sixteen micro-mixing cups for effective and rapid mixing of fuel and air in a compact package. The full scale injector is rated at 1.3 MWth when operating on natural gas at 12.4 bar (180 psi) combustor pressure. The injector operated without flash back on fuel mixtures ranging from 100% natural gas to 100% hydrogen and emissions were shown to be insensitive to operating pressure. Ultra-low NOx emissions of 3 ppm were achieved at a flame temperature of 1750 K (2690 °F) using a fuel mixture containing 50% hydrogen and 50% natural gas by volume with 40% nitrogen dilution added to the fuel stream. NOx emissions of 1.5 ppm were demonstrated at a flame temperature over 1680 K (2564 °F) using the same fuel mixture with only 10% nitrogen dilution, and NOx emissions of 3.5 ppm were demonstrated at a flame temperature of 1730 K (2650 °F) with only 10% carbon dioxide dilution. Finally, using 100% hydrogen with 30% carbon dioxide dilution, 3.6 ppm NOx emissions were demonstrated at a flame temperature over 1600 K (2420 °F). Superior operability was achieved with the injector operating at temperatures below 1470 K (2186 °F) on a fuel mixture containing 87% hydrogen and 13% natural gas. The tests validated the micro-mixing fuel injector technology and the injectors show great promise for use in future gas turbine engines operating on hydrogen, syngas or other fuel mixtures of various compositions.


1989 ◽  
Vol 21 (4-5) ◽  
pp. 145-155 ◽  
Author(s):  
R. Méndez ◽  
J. M. Lema ◽  
R. Blázquez ◽  
M. Pan ◽  
C. Forjan

We have evaluated the utility of applying anaerobic digestion treatment to the leachates from two landfill sites receiving solid urban refuse from populations of similar standards of living. Both tips are located in the same area and have very similar climates, but they differ as regards the length of time they have been operated. The leachates from the older tip have much lower levels of organic load, 40% of which was refractory to the anaerobic digestion treatment applied. The digestibility of leachates was studied by using a semicontinuous suspended sludge system.It was possible to remove up to 65% of the soluble COD of leachates from the young tip by means of an anaerobic filter working at HRTs less than 2 days. This system proved to be highly stable when its operating conditions were subjected to perturbations similar to those likely to be suffered by a full-scale plant.


Author(s):  
Hammad Siddiqui ◽  
Mariam Elnour ◽  
Nader Meskin ◽  
Syed Zaidi

Reverse Osmosis (RO) is an efficient and clean membrane-based technology for water desalination. This work presents a full-scale seawater reverse osmosis (SWRO) desalination plant simulator using MATLAB/Simulink that has been validated using the operational data from a local plant. It allows simulating the system behavior under different operating conditions with high flexibility and minimal cost.


Author(s):  
Davide Laera ◽  
Giovanni Campa ◽  
Sergio M. Camporeale ◽  
Edoardo Bertolotto ◽  
Sergio Rizzo ◽  
...  

This paper concerns the acoustic analysis of self–sustained thermoacoustic pressure oscillations that occur in a test rig equipped with full scale lean premixed burner. The experimental work is conducted by Ansaldo Energia and CCA (Centro Combustione Ambiente) at the Ansaldo Caldaie facility in Gioia del Colle (Italy), in cooperation with Politecnico di Bari. The test rig is characterized by a longitudinal development with two acoustic volumes, plenum and combustion chamber, coupled by the burner. The length of both chambers can be varied with continuity in order to obtain instability at different frequencies. A previously developed three dimensional finite element code has been applied to carry out the linear stability analysis of the system, modelling the thermoacoustic combustion instabilities through the Helmholtz equation under the hypothesis of low Mach approximation. The heat release fluctuations are modelled according to the κ-τ approach. The burner, characterized by two conduits for primary and secondary air, is simulated by means of both a FEM analysis and a Burner Transfer Matrix (BTM) method in order to examine the influence of details of its actual geometry. Different operating conditions, in which self–sustained pressure oscillations have been observed, are examined. Frequencies and growth rates of unstable modes are identified, with good agreement with experimental data in terms of frequencies and acoustics pressure wave profiles.


Author(s):  
U Campora ◽  
M Figari

The paper describes a mathematical model for the dynamics simulation of ship propulsion systems. The model, developed in a MATLAB-SIMULINK software environment, is structured in modular form; the various elements of the system are described as individuals blocks (hull, prime mover, gear, waterjet, etc.) and linked together to take their interactions into account. In this way it is possible to characterize the dynamic behaviour of both the single component and the whole propulsion plant. The model may be used to analyse the system response at off-design and transient conditions. In particular, the developed computer simulation code may be considered as a useful tool to facilitate the correct matching of the prime mover (diesel or gas turbine) to the propulsor (waterjet or propeller) in a wide range of operating conditions. The paper shows the application of the methodology to a cruise ferry used to validate the model results through a full-scale test campaign conducted by the authors during normal operation of the ship.


1995 ◽  
Vol 32 (12) ◽  
pp. 35-42 ◽  
Author(s):  
G. Yilmaz ◽  
I. Öztürk

The objective of this study is to determine the inert soluble COD of wastewaters from the fermentation industry. In this context, a series of experiments were performed for various effluents from baker's yeast industry including raw process wastewater, anaerobic pre-treatment plant effluents, domestic and washing waters mixture. The inert COD ratio (SISO) for the raw effluents from baker's yeast industry was determined as 0.1. This ratio was in the range of 0.20 to 0.30 for the anaerobically pre-treated effluents. TheSISO ratios for the wastewater simulating the effluent of the existing full-scale aerobic treatment plant have varied from 0.18 to 0.48. Such a large variation has been originated from the operating conditions of the existing full-scale anaerobic treatment plants. The higher volumetric loading rates and shorter sludge retention times correspond the lower SISO ratios for the full-scale anaerobic treatment systems in general.


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