Extensive Dynamic Analyses to Achieve Stringent Noise and Vibration Levels for an Offshore Reciprocating Compressor System

2011 ◽  
Author(s):  
Andre´ Eijk ◽  
Hans Elferink
Keyword(s):  
Operating Conditions ◽  
Reciprocating Compressor ◽  
Gas Well ◽  
Noise And Vibration ◽  
Term Operation ◽  
The North ◽  
Final Design ◽  
The North Sea ◽  
System Requirements

During the lifetime of an existing gas well, located in the D15FA/FB field in the North Sea, the pressure has dropped and consequently production is reduced. A depletion compressor had to be added to this existing platform to increase the production. This sounds easy but has been very challenging due to physical, noise and vibration restrictions. For this platform it appeared that a reciprocating compressor was the best choice based on its flexibility with respect to the specified operating conditions, available power, and efficiency. However, despite of several advantages a disadvantage of a reciprocating compressor is that it generates additional vibrations and noise in the living quarters, which are located close to the compressor system. The specified requirements, not to exceed the allowable noise limits in the living quarters and the vibration limits of the complete compressor system, could in this specific case, not be met with straightforward solutions. This presentation will explain the dynamic analysis and the efforts taken in compressor, skid, motor, piping and deck design to meet the very stringent specified requirements and to ensure a safe and reliable system for the long term operation. Special attention will be given to the measures taken to reduce the excitations acting on the platform, and the mechanical and acoustical analysis that have led to the final design of this reciprocating compressor system. The solutions that have been developed can be regarded as non-standard and have resulted in new directions in solving very demanding system requirements.

scholarly journals Long-term series in ichthyoplankton: sole and sprat at French coast of the North Sea from 1975 to 1994

1998 ◽  
Vol 21 (1) ◽  
pp. 113-121 ◽  
Author(s):  
Daniel Woehrling ◽  
Geneviève Le Fèvre-Lehoërff
Keyword(s):  
North Sea ◽  
The North ◽  
The North Sea

Investigation of long-term operation and biomass activity in a membrane bioreactor system

2011 ◽  
Vol 63 (9) ◽  
pp. 1906-1912 ◽  
Author(s):  
Simos Malamis ◽  
Andreas Andreadakis ◽  
Daniel Mamais ◽  
Constantinos Noutsopoulos
Keyword(s):  
Membrane Fouling ◽  
Membrane Bioreactor ◽  
Extracellular Polymeric Substances ◽  
Operating Conditions ◽  
Term Operation ◽  
Solids Retention ◽  
Biomass Activity ◽  
Long Term Performance ◽  
Term Performance

The aim of this work was to evaluate the long-term performance of a Membrane Bioreactor (MBR) that operated continuously for 2.5 years and to assess membrane fouling and biomass activity under various operating conditions. Furthermore, a method for the characterisation of influent wastewater was developed based on its separation into various fractions. The MBR system operated at the solids retention times (SRT) of 10, 15, 20 and 33 days. The increase of SRT resulted in a decrease of the fouling rate associated with the reduction of extracellular polymeric substances. Moreover, the SRT increase resulted in a significant reduction of the Oxygen Uptake Rate (OUR) due to the lower availability of substrate and in a notable decrease of the maximum OUR since high SRT allowed the development of slower growing microorganisms. Biomass consisted of small flocs due to extensive deflocculation caused by intense aeration. Finally, the method developed for wastewater characterisation is straightforward and less time consuming than the usual method that is employed.

scholarly journals The ‘Yellow Danger’? Global forces and global fears in the North Sea and beyond (1600–1950)

2015 ◽  
Vol 27 (4) ◽  
pp. 743-754
Author(s):  
Matthias van Rossum
Keyword(s):  
Labour Market ◽  
North Sea ◽  
Labour Markets ◽  
Labour Relations ◽  
The North ◽  
15Th Century ◽  
Global Connections ◽  
The North Sea

Since direct shipping routes between Europe and Asia opened up at the end of the 15th century, the growing intercontinental and regional shipping connections resulted in increasing entanglements between European and Asian maritime labour markets. This article analyses the long term development of the connections between European and Asian maritime labour markets and its impact on socio-cultural (and labour) relations through three elements: first, the changing connections between European and Asian maritime labour markets; second, the changing nature of European and Asian maritime labour markets and its influence on the positions of sailors; and third, the changing relations between European and Asian sailors and its effects on the reactions and interactions in a globalising maritime labour market. It explores how these changing global connections shaped encounters between European and Asian sailors on (intercontinental) shipping in and from the North Sea region, and how it affected the positions and reactions of its workers.

The history and future of the North Sea benthos

1978 ◽  
Vol 76 (1-3) ◽  
pp. 193-200
Author(s):  
P. E. P. Norton
Keyword(s):  
North Sea ◽  
Bottom Type ◽  
The North ◽  
Late Tertiary ◽  
Long Term Changes ◽  
History Of ◽  
The North Sea ◽  
Temperature Depth

SynopsisThis is a brief review intended to supply bases for prediction of future changes in the North Sea Benthos. It surveys long-term changes which are affecting the benthos. Any prediction must take into account change in temperature, depth, bottom type, tidal patterns, current patterns and zoogeography of the sea and the history of these is briefly touched on from late Tertiary times up to the present. From a prediction of changes in the benthos, certain information concerning the pelagic and planktonic biota could also be derived.

scholarly journals Warm-water decapods and the trophic amplification of climate in the North Sea

2010 ◽  
Vol 6 (6) ◽  
pp. 773-776 ◽  
Author(s):  
J. A. Lindley ◽  
G. Beaugrand ◽  
C. Luczak ◽  
J.-M. Dewarumez ◽  
R. R. Kirby
Keyword(s):  
North Sea ◽  
Warm Water ◽  
Climate Signal ◽  
Southern North Sea ◽  
The North ◽  
Ecosystem Shift ◽  
The North Sea ◽  
Induced Changes ◽  
Water Species

A long-term time series of plankton and benthic records in the North Sea indicates an increase in decapods and a decline in their prey species that include bivalves and flatfish recruits. Here, we show that in the southern North Sea the proportion of decapods to bivalves doubled following a temperature-driven, abrupt ecosystem shift during the 1980s. Analysis of decapod larvae in the plankton reveals a greater presence and spatial extent of warm-water species where the increase in decapods is greatest. These changes paralleled the arrival of new species such as the warm-water swimming crab Polybius henslowii now found in the southern North Sea. We suggest that climate-induced changes among North Sea decapods have played an important role in the trophic amplification of a climate signal and in the development of the new North Sea dynamic regime.

The macrobenthos of the Beatrice Oilfield, Moray Firth, Scotland

1986 ◽  
Vol 91 ◽  
pp. 221-245
Author(s):  
J. P. Hartley ◽  
J. D. D. Bishop
Keyword(s):  
New Records ◽  
Benthic Communities ◽  
Fine Sand ◽  
Faunal Composition ◽  
Qualitative And Quantitative ◽  
The North ◽  
Moray Firth ◽  
Faunal Communities ◽  
The North Sea

SynopsisThe benthic ecology of the Beatrice Oilfield area is described from preproduction surveys carried out in 1977, 1980 and 1981. and from earlier published information. Variations in the water depth (from 33m to > 60 m) over the area were mirrored by sedimentary and faunal gradients. The sediments ranged from very fine, through fine to medium sands and were inhabited by faunal communities characterised by Thyasira flexuosa, Tellina fabula and Tellina pygmaea, respectively. Two fades of the fine sand community were noted, typified by the abundance of Thyasira flexuosa in muddier sediments and Crenella decussala in coarser deposits. Localised patches of shell gravel in which the fauna was characterised by reduced densities of Tellina fabula with elevated numbers of Scoloplos armiger and Lumbrineris gracilis occurred in medium depths. Examination of the faunal composition indicates that the Beatrice Oilfield lies at the interface between Glemarec's infralittoral and coastal étages.Comparison with earlier reports of the benthic communities of the area suggests a degree of long term persistence of the fauna in qualitative and quantitative terms. A list of all taxa found during the recent surveys is given; this includes a number of new records from the North Sea.

scholarly journals Comparing conceptual frameworks for a fish community MSY (FCMSY) using management strategy evaluation—an example from the North Sea

2019 ◽  
Vol 76 (4) ◽  
pp. 813-823 ◽  
Author(s):  
Robert B Thorpe ◽  
José A A De Oliveira
Keyword(s):  
North Sea ◽  
Management Strategy ◽  
Fish Community ◽  
Parameter Uncertainties ◽  
Management Strategy Evaluation ◽  
The North ◽  
Strategy Evaluation ◽  
The North Sea ◽  
Definition Of

Abstract Maximum sustainable yield (MSY) is a well-established concept that is mandated by legislation, and has a clear theoretical meaning in terms of a single stock. However, its definition is problematic in a multispecies setting, which makes it more difficult to apply the MSY principle. In this study of the North Sea fish community, we consider several possible MSY candidates, and evaluate them in terms of their ability to produce optimum long-term yield whilst avoiding unacceptable risk of stock impairment. We perform this evaluation with an ensemble of size-structured models using a management strategy evaluation approach, in which harvest control rules (HCRs) are used to determine levels of fishing as a function of the proposed MSY target and stock status, taking account of recruitment and model parameter uncertainties. We find that HCRs of the type considered here are always useful in the scenarios we tested, as they reduce overfishing risk much more than average long-term yield. This is independent of the precise form of the HCR, so it is more important to implement one rigorously than obsess over the rule details. For a lax definition of overfishing, which accepts relatively severe stock depletion (B < 10% B0), and using HCRs, risks are “low” across all strategies, and the Nash equilibrium is the best performing MSY approach considered here. For more stringent definitions of “at risk” (e.g. likelihood of B < 20% of B0), the application of HCRs can allow a range of alternative formulations of MSY. Thus, the definition of MSY may be sensitive to judgements about acceptable levels of risk, and consistent application of a sensible management framework may be more important than developing the best possible theoretical definition of MSY.

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