Filtration of Gas Turbine Intake Air in Offshore Installations: The Gap Between Test Standards and Actual Operating Conditions

Author(s):  
Olaf Brekke ◽  
Lars E. Bakken ◽  
Elisabet Syverud

Gas turbine performance deterioration caused by fouling in the compressor section is a well known phenomenon in offshore installations. This performance deterioration not only increases fuel consumption and emissions but also has a severe economic impact when it reduces oil and gas production. Because fouling in the compressor section is commonly caused by intake air contamination, gas turbines offshore have air inlet filtration systems in order to limit the amount of ingested contaminants. Many different filtration systems from various suppliers are in operation offshore. Manufacturers supply documentation for their filtration system based on several international standards, and it can be challenging for the operator to make a direct comparison of different filtration systems. The comparison is further complicated by the fact that the characteristic offshore challenges related to salt and moisture in the intake air are not adequately covered in international standards, and these challenges are handled and documented differently among the manufacturers. This paper analyzes the challenges related to choosing the best filter solution for an offshore gas turbine installation based on data from offshore sites in the North Sea. The relevance of test requirements in applicable international standards and available supplier documentation is evaluated based on actual operating conditions offshore. Deviations among international test standard requirements, available manufacturer documentation, and actual operating conditions offshore are identified, and improved test requirements are suggested. In addition, this paper addresses the long-term effects of filter contamination and methods for intake filter monitoring based on data from offshore sites in the North Sea.

Author(s):  
M. H. P. Kimm ◽  
D. Langlands

This Paper covers various aspects with respect to the selection and operation of air filtration associated to offshore gas turbine installations. As the Offshore North Sea industry moves into its second decade, Operators are still trying to improve machine availability and reduce maintenance costs. One of the main contributing factors in their failure to achieve the ideal condition has been poor inlet air filtration caused by bad design and incorrect filter selection. The majority of offshore installations are equipped with filter systems which were originally designed for use on ocean-going vessels. The performance of what has become known as the “High Velocity Salt Eliminator System” has, in most cases, been unsatisfactory, thereby creating a necessity for a continuing search into alternative filter systems. The experiences of most Operators in the North Sea have been very similar, and examination of the platform environment explains why this should be the case. To emphasize the affects of poor air filtration and the savings that can be achieved by the Operator in recognising and correcting the problems, specific reference is made to the experience of Mobil North Sea with the Beryl Alpha Production Platform.


BMJ Open ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. e037558
Author(s):  
Anne Waje-Andreassen ◽  
Øyvind Østerås ◽  
Guttorm Brattebø

ObjectivesFew studies have described evacuations due to medical emergencies from the offshore installations in the North Sea, though efficient medical service is essential for the industrial activities in this area. The major oil- and gas-producing companies’ search and rescue (SAR) service is responsible for medical evacuations. Using a prospective approach, we describe the characteristics of patients evacuated by SAR.Design and settingA prospective observational study of the offshore primary care provided by SAR in the North Sea.MethodsPatients were identified by linking flight information from air transport services in 2015/2016 and the company’s medical record system. Standardised forms filled out by SAR nurses during the evacuation were also analysed. In-hospital information was obtained retrospectively from Haukeland University Hospital’s information system.ResultsA total of 381 persons (88% men) were evacuated during the study period. Twenty-seven per cent of missions were due to chest pain and 18% due to trauma. The mean age was 46.0 years. Severity scores were higher for cases due to medical conditions compared with trauma, but the scores were relatively low compared with onshore emergency missions. The busiest months were May, July and December. Weekends were the busiest days.ConclusionThree times as many evacuations from offshore installations are performed due to acute illness than trauma, and cardiac problems are the most common. Although most patients are not severely physiologically deranged, the study documents a need for competent SAR services 24 hours a day year-round. Training and certification should be tailored for the SAR service, as the offshore health service structure and geography differs from the structure onshore.


Author(s):  
P. Whomersley ◽  
G.B. Picken

Inspection videos of four offshore platforms in the central and northern North Sea were used to study the development of fouling communities on clamps and guides of oil export risers over an 11-y period (1989–2000). Results from multivariate analyses (multi-dimensional scaling and analysis of similarities) indicated that distinct assemblages developed in different geographical locations. These differences were mainly due to the protracted development of theMetridium senile(Cnidaria: Actinaria) zone on the northern sector platforms. The vertical zonation of fouling organisms was similar on all installations, although the water depth at platform locations varied from 80 to 169 m, indicating that fouling organisms display a wide bathymetric tolerance. This study has highlighted the value of long-term data present in operational inspection videos for the study of fouling communities.


Author(s):  
Beatriz Alonso Castro ◽  
Terje Birkenes ◽  
Huib Oosterveld

Decommissioning is an emerging sector in the UK and Norway, accounting for 2% of total industry expenditure in 2010 increasing to 8% in 2017. In accordance with existing regulations in the North Sea (OSPAR), dumping, and leaving wholly or partly in place disused offshore installations within the maritime area is prohibited. Over the next eight years, 200 platforms are expected to be removed in the North Sea. There are a number of methods to remove offshore installations: Piece small, Reverse installation and Single lift. In the Single lift approach the jacket or the topside is removed in one piece, minimizing significantly the time offshore and therefore the safety and health incidents. But the Piece Small and Reverse Installation are the most common methods and are established and secure although are time consuming and labor intensive [1]. Several potential candidates for single lift technology at varying levels of technical readiness were considered in the past. The majority of the concepts remained on the drawing board, while some were awaiting project commitment. The only that was matured further than this is the Pioneering Spirit. Yme, its first commercial lift, gave this concept the “proven” status. The Yme MOPU, owned by Repsol, was a jack-up type platform standing on three steel legs of 3.5 m diameter. The dry weight of the MOPU was approximately 13,500 t. The Yme MOPU was a challenging unit to remove mainly for three reasons: The platform motions due to the lack of stiffness in the leg support, its position in contact with the caisson wellhead platform, and the fact that the legs could not be pre-cut before the operation. The method selected to remove the platform was Single lift, using the dynamically positioned platform installation and removal vessel Pioneering Spirit. The lifting arrangement consisted of 12 lift beams combined and connected in pairs to yokes. Five specifically designed yokes were installed. The yokes connect the TLS with the MOPU. The structural integrity of each interface was assessed with FE analysis. The Ballast system was used to provide additional clearance. Pioneering Spirit has a total of eighty-seven ballast water tanks, including four so called ‘Quick Drop Ballast Water Tanks’. The removal of the MOPU was performed successfully the 22nd August 2016, after two days work offshore.


Author(s):  
Mina Hynne Bjerkelund

This paper will give a brief presentation of experience gained over the last 5–10 years of decommissioning of offshore installations in the North Sea. Focus is given to safety and environment issues, as this is the driven factor towards decommissioning and deconstruction of offshore installations. The establishment of cleaning criteria is based on experience from The Ekofisk I Field where a number of installations should be out of production and shut down prior to final disposal. The disposal solution was not yet defined; therefore a “cold phase” was defined. The installations would stay in place for an unknown period of time. Cleaning of large storage tanks, such as Brent Spar, Maureen Alpha and The Doris Tank is a challenge due to the size and layout of the tanks and the content, such as H2S, wax, scale, sediments, etc. Special cleaning techniques and methods are developed for each tank. Reuse of installation or part of the installation is a target. Re use of the installations to what they were originally designed for, has been a main issue, but not yet succeeded. In the North Sea, no installations so far have been re used. Lot of effort is put into risk management and waste management. Risk related to deconstruction work, both onshore and offshore, is a major concern. All statistics demonstrates challenges towards work performance in deconstruction projects. It is important for the offshore industry to maintain a good reputation and to be a reliable and orderly partner for safety and environmental aspects of the industry.


Author(s):  
Conrad Carstensen ◽  
Roald Skorping

In this paper experience with some of the first gas turbines equipped with dry low NOx combustors installed in the North Sea is presented. The case history covers LM2500 and LM6000 gas turbines. The paper outlines further some of the technical challenges for future applications in conformance with recent revisions of power plant air emission guidelines.


Author(s):  
R. B. Spector ◽  
L. S. Cimino

Approximately 50 years of offshore oil exploration drilling and production have led to refined techniques and equipment selection criteria. Gas turbines have established themselves as the prime source of energy transfer in that sector of the industrial marketplace where space and weight are of major importance. The increased worldwide demand for petroleum has pushed offshore platforms into deeper waters requiring further sophistication in the allocation of space, weight and maintenance resources. The aeroderivative gas turbine meets the above criteria and in addition offers the platform designer high thermal efficiency and system flexibility coupled with ease of maintenance. This paper presents a summary of experience gained in over 10 years of operation of the General Electric LM2500 gas turbine on platforms in the North Sea. Although all of the circumstances that may be encountered cannot be adequately covered, highlighting the events which occurred in over one million hours of operation presents the potential user with a better understanding of the uniqueness of this type application. The advantages and the reliability of the aeroderivative gas turbine are also discussed. The LM2500 gas turbine was first introduced into off-shore operation in the Norwegian sector of the North Sea in November 1979, after successful application in gas compression and transmission duty on pipelines and other on shore facilities.


Sign in / Sign up

Export Citation Format

Share Document