Large-diameter pipeline systems

Three major proposals have been advanced which would provide large diameter pipeline transportation for North Slope gas as well as that gas which may become available in Canada s Northwest frontier areas. The Gas Arctic Systems group has proposed a 1550 mile system which would connect the Prudhoe Bay area with an extension of the existing Alberta Gas Trunk Line system in Alberta, Canada. This system could make gas available to U.S. West Coast and Midwest markets through pipeline interconnections with existing pipeline systems. Spon-... 

Inhibitors act to control corrosion, particularly in piping systems. They form a very thin (perhaps monomolecular) adsorbed layer that acts as a barrier. Film-forming amines are a common example. Because inhibitors may locally de-adsorb, they are usually continuously injected. For large-diameter pipelines, batch inhibition may be necessary. Inhibition is usually not permitted in processes for high-purity products. 

Hydrogen gas producers in the United States and Europe have accumulated decades of experience with transmission pipelines fabricated from carbon steels and currently operate over 1500 km of pipeline [13,49]. Large-diameter piping systems (>2.5cm) used for local distribution of hydrogen gas in large-scale industrial operations also make extensive use of low-alloy steels, such as the chromium-molybdenum steels, particularly for service at elevated temperature. Pipelines and piping fabricated from low-alloy and carbon steels have functioned safely and reliably in hydrogen gas service. 

Most major urban utilities typically have several large-diameter pipelines of different ages, installed in soils of varying corrosivity, operated and pressurized to different levels, possibly overloaded and deteriorated to unknown levels. Many of the records about the pipelines in major urban areas are either difficult to find or lost over the years, and arc often not readily available. Proactive utilities are beginning to compile the data and create databases with basic pipeline information, for example, age, material, pipeline plan and profile drawings, etc., and potential consequences of pipe failure at various locations in the system. 

Since large volumes are needed to economically justify North Sea systems, pipe diameters will be large, probably 30"-36", or bigger if the pipe can be physically laid. Vail thickness will be the heaviest that can be laid, which for 36" pipe may currently be 1" wall thickness. Compressor station spacing and compression ratio will be different from onshore systems due to the high coat of providing a separate pipeline compressor platform, and because the pipeline systems will In most cases have to pick up gas from various fieldsalong the route located at fixed points, and these points will tend to dictate the location of pipeline compressor stations. 

It follows from economical comparison that coal-log pipeline is cheaper than truck transport for distances longer than 65 km and pipe diameter D = 200 mm. For D = 500 m even for distance over 25 km. Compared with railway, the transport cost is on the level of unit trains. For large quantity of coal it could be even less. Another advantage is given by fact that length of pipeline is usually at least about 30 % lower than that of the railway. From environmental protection point of view, capsule pipeline, similarly as slurry pipeline, is dust free and noiseless. In spite of these advantages the utilisation of coal-log pipeline system could expect only for transport of coal from new mines to power stations, especially in mountains areas without railways and highways or in heavy populated and industrial areas, where railway is overloaded. 

A proper geometric design of the system in order to get a laminar flow with minimum turbulence, as in pipelines of large diameters and avoid abrupt changes or streamline bends. 

Wul, G., Xu, J., and Miles, J., Polymer drag reduction in large diameter coal log pipeline. Proceedings of the International Technical Conference on Coal Utilization and Fuel Systems, 23, 889-900 (1998). 

Conditions where the pipe is under cyclic loads may result in increased crack growth rates. Operating pressures for a large-diameter pipe can measure up to 8700 kPa (1250 psi). The pipeline pressure continually fluctuates due to loadiug aud unloading of product and is influenced by pump activity. This applies to both gas and liquid hues but has greater influence in liquid systems [6]. 

Example 1 Application of the total mechanical-energy balance to noncom-pressible-flow systems. Water at 61°F is pumped from a large reservoir into the top of an overhead tank using standard 2-in.-diameter steel pipe (ID = 2.067 in.). The reservoir and the overhead tank are open to the atmosphere, and the difference in vertical elevation between the water surface in the reservoir and the discharge point at the top of the overhead tank is 70 ft. The length of the pipeline... 

In the low-pressure amine absorption system, a low stripper pressure is used to keep stripper reboiler duty as small as possible. In the high-pressure TEG absorption system, there is a smaller dependence of reboiler energy on pressure. A higher pressure in the stripper reduces the compression costs to raise the recovered carbon dioxide gas up to the required pipeline pressure for sequestration. Therefore, there is an optimum economic stripper pressure (ISOpsia) that balances compression costs with stripper reboder energy cost. The stripper distillate is cooled to 110 °F to minimize the amount of water in carbon dioxide gas product from the stripper reflux drum. Diameters of the columns are very large due to the enormous throughput. 

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