Transit Time Ultrasonic Flow Meters for Natural Gas Measurement

The advantages of ultrasonic flow meters are well know — no line obstructions, large turndown ratio, bi-directionality, high accuracy — and ultrasonic meters are now widely used within the gas industry in a wide variety of applications. Ultrasonic meters are available in several different configurations ranging from high accuracy multipath spoolpiece meters to single path hot-tapped meters. While all of these meters operate on the same basic transit-time principle, there are significant differences in their operational aspects. This paper is intended to review the basic concepts of ultrasonic flow meters, to clarify the differences listed, and to explain how ultrasonic meters should be specified.

Development of a Simulator-Based Training Program

This paper presents the Con Edison Gas Control experience in developing a simulator-based training program. The simulator-based training is now part of the Con Edison safety training as it allows the gas controllers to get familiar with abnormal and emergency conditions and learn to react promptly to contain the problem. The process of developing a training course required a sustained and dedicated effort. A number of iterative steps were necessary as we learned that the development of models and scenarios for training is a specific activity which is different from other activities such as simulator-based studies. The simulator-based training course we developed has two parts: basic concepts and Con-Edison specific lessons. Each part required a different lesson format and issues related to the development of the lessons are discussed.

Analysis for Wrinkling Behavior of Girth-Welded Line Pipe

The paper presents results for finite element analysis of full-sized girth-welded specimens of line pipe and compares these results with the behavior exhibited by test specimens subjected to constant axial force, internal pressure and monotonically increasing curvatures. Recommendations for the ‘best’ type of analytical finite element model are given. Comparisons between the behavior predicted analytically and the observed behavior of the experimental test specimens are made. The mechanism of wrinkling is explained and the evolution of the deformed configurations for different wrinkling modes is examined. It is concluded that the analytical tools now available are sufficiently reliable to predict the behavior of pipe in a manner that was not previously possible and that this should create a new era for the design and assessment of pipelines if the technology is properly exploited by industry.

Numerical Investigation of Jamming of Solid Particles in a Straight Pipe

The flow of fluids containing solid particles is numerically simulated in order to determine the critical parameters of the system leading to a jam. Two parameters are varied: the volumetric density of solid particles and the velocity of fluid flow. The energy dissipation in the system is due to dry friction losses and collisions. The results presented are based on the mathematical models of granular materials treated as multibody systems with variable topology. The fluid flow is considered to be potential. It is shown that jamming strongly depends on the volumetric density of particles and fluid velocity. The results of numerical experiments are in qualitative agreement with physical experiments of flow of spherical particles in a pipe.

Gas Turbine Compressor Unit Repowering

This paper presents how a major U.S. gas transmission and storage company restored gas storage peaking capacity by repowering obsolete gas turbine compressor units. Consumers Power Company’s Ray Field located in Macomb County, Michigan, USA, was developed as a 44 BCF working capacity gas storage field in 1966. Due to the high deliverability, the field is operated as a peaking reservoir, handling rates as high as 500 MMCFD on injection and 1,200 MMCFD on withdrawal. Ten (10) 2,750 horsepower gas turbine driven 4-stage centrifugal compressor units were installed in the mid to late 1960’s at the field. The compression is operated 2, 4 and 8 stage, as needed, to cover storage pressures of 450 to 1800 psig. Each centrifugal compressor is driven by a Pratt Whitney (PW) GG-12 Gas Generator firing into a Cooper-Bessemer (CB) RT-27 Power Turbine. By 1980 parts and maintenance services for the PW GG-12 Gas Generator became very expensive to non-existent. Aircraft use of the GG-12 (JT-12) had been phased out. Consumers Power, with 13 of these turbines on their system, was becoming the only remaining user. In the mid 1980’s four (4) of the Ray Field gas turbine compressor units were replaced with two (2) 6,000 horsepower reciprocating engine compressor units. These replacements maintained the deliverability of the field and provided salvageable engines and other parts to maintain the six (6) remaining turbines. However, by 1993 maintenance parts returned as a major problem as well as unit availability on the 6 remaining turbine units. In 1994 Consumers Power committed to a gas turbine unit repowering program as the preferred choice over unit replacement. Two (2) refurbished Solar Centaur T4500 Gas Turbine drives were purchased and installed to repower 2 of the obsolete turbine units. These installations have been very successful. Existing compressors, foundations, piping, coolers and auxiliary systems were re-used with only minor modification. The complete installed cost for repowering was about 33% of the cost experienced for replacement. Installation was completed within eight (8) months of project commitment. The low emission rates from the Solar SoLoNOx Combustors allowed short lead time (6 months) on air emissions permit. New sound attenuation enclosures met the new local noise ordinance and replaced equipment that had been a source of local complaint. PLC based controls improved reliability and flexibility of operation. The additional horsepower available from the T4500 Turbine (4,300 vs 2,750) allows for increased future capacity. Because of the success of the Ray Turbine Repowering Project, Consumers Power has committed to 2 more refurbished Solar Centaur T4500 Units to repower PW/CB Turbines at the St Clair Compressor Station. Solar is scheduled to delivery these 2 units by year-end 1995 for installation in 1996.

New Applications and Advancements in Magnetic Bearing Systems for Pumps and Compressors

Magnetic bearings have been used in a variety of pipeline applications, but have not yet achieved industry wide acceptance. They continue to be installed in more innovative and challenging applications which take advantage of the efficiency gains and other information they make available to end users. Despite the promise offered by the technology, issues concerning cost and reliability remain the primary concern among end users. This sets the stage for a discussion of recent operating experience, and advancements currently underway to address the cost and reliability issues. Such advancements include digital control, simplified control hardware, feed forward algorithms and on-line diagnostic capability.

Interrelationship Between the Efficiency Characteristics and the Pressure Head Gradients Among Axial Flow Pumps

There is a correlation between the efficiency of the pump to the head produced. On the axial flow pump, whose efficiency characteristic is favorable, the pressure head gradient between the impeller inlet and the outlet sections, at an equivalent flow rate, may become larger than that for the less favorable axial flow pump. This fundamental interrelation may be held in the flow passage regardless to the flow rate whichever they are operated at design or off design flow rate. There may be a direct correlation between the efficiency of an axial flow pump and the ratio of the discharge valve cross section divided by the pipeline cross section. The smaller this ratio is the better the pressure head gradient is for the same flow rates. This ratio may be useful to estimate relative grade of heads, pressure head gradients, internal flow conditions, and efficiency characteristics among axial flow pumps.

Mechanics of Buried Chilled Gas Pipelines

This paper examines the factors influencing the modelling of soil-pipeline interaction for a pipeline which is used to transport chilled gas. The soil-pipeline interaction is induced by the generation of discontinuous frost heave at a boundary between soils with differing frost susceptibility. The three-dimensional modelling takes into consideration the time-dependent evolution of frost heave due to moisture migration, the creep and elastic behaviour of the frozen soil and flexural behaviour of the embedded pipeline. The results of the computational model are compared with experimental results obtained from the frost heave induced soil-pipeline interaction test performed at the full scale test facilities in Caen, France.

Problems of Restructurisation and Renewal of Old Gas Distribution Network in Wroclaw

Changing environment, growing demand for gas for heating, and shut down of old gas plant, cause necessity of restructurisation of the old gas distribution network in the city. Aging distribution network, replacement of manufactured gas by natural gas and rapid growth in number of leaks cause urgent necessity of replacement and rehabilitation of the old gas pipelines. Modern materials and technologies have enabled rehabilitation gas pipelines in the narrow busy streets of the city.

Recommissioning NPS 30 Pipeline

This paper will discuss all the steps taken to reclaim an 80 kilometre (50 Mile) NPS 30 (30″) pipeline loop, including the project planning, the labour requirements, the techniques utilized to complete the various stages of the project, some of the unique problems encountered, as well as, some options that were examined for hydrostatic test leak detection and water treatment. This project was a component of the Trans Mountain, Cdn $30 million, Stage II capacity expansion. This component of Stage II resulted in an increase of 3,000 m3/d (18,909 barrel/d) to the overall pipeline capacity achieving a 36,300 m3/d sustainable pipeline pumping capacity1 (230,000 barrel/d).