Explosions in Gas Turbine Lube Oil Reservoir Result in Installation of Dry Gas Seal System

Author(s):  
Lawrence R. Ferrill ◽  
N. Daryl Ronsky ◽  
Tim A. Harris

Mechanical dry gas seal systems were retrofitted into two centrifugal natural gas compressors which are located offshore in the Norwegian sector of the North Sea. The project was initiated after a fire and several gas explosions had occurred in the gas turbine lube oil reservoir. These incidents were a result of gas leaking from the compressor’s seal oil system and then migrating via the lube oil lines into the reservoir. The dry gas seal systems have eliminated gas leakage into the turbine lube oil reservoir, eliminating the hazard of gas explosion. The retrofits have also provided additional benefits including reductions in space and weight, reduced power usage, reduced maintenance, and elimination of seal oil consumption which had been up to 440 gal./day (2000 liters/day).

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.


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.


Author(s):  
J. M. Overli ◽  
R. Magnusson

This paper describes the results obtained from a study commissioned to ascertain the optimum drive arrangements for the gas compression machinery to be installed on an integrated platform in the North Sea. The study was restricted to two main drive type alternatives: - All compressor stages on one shaft driven by a variable speed aero-derivative gas turbine. - All compressor stages with separate, constant speed, electric motor drives. The study took into account drive option and shafting arrangements with regard to flexibility of operation, weight, area, lay-out, foundation/alignment, waste heat recovery requirements, availability/reliability, safety, maintenance, fuel consumption, investment cost and operational experience. For the specific case studied, the overall conclusion was in favour of the gas turbine drive alternative.


Author(s):  
J. G. Kiernan

The gas turbine compression and power generation systems for the Statfjord B platform required custom designed systems and significant design efforts. This paper summarizes many of the studies performed and reviews the overall project scope. The engineering considerations are presented to assist other gas turbine users and designers with their application considerations.


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.


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