Design Approach for Trans –Sahara Gas Pipeline Transmission
Abstract
Natural gas is poised to occupy a more prominent place in the global energy balance, coupled with other renewable energy sources, natural gas is an energy source of choice for the development of Africa and offers a vehicle for its integration with the world economy. The Economic Sustainability and expected benefits of Nigerian gas reserves are estimated at 5 trillion cubic meters – equal to roughly ten years of consumption of the EU. The modeling approach for long distance natural gas pipeline is optimized and design for the minimum installation cost. In this research paper the minimum cost for the installation of long gas pipeline is obtained by designing the different set of pipeline networks for which the installation costs are estimated and compared with the minimum capital cost. Various available pipeline systems are designed by varying the compressor station spacing for different standard pipe diameters. Accurate installation costs for each obtained pipeline network are estimated by using an advanced cost estimating computer program which uses real and updated data for the estimation. These total costs of the various pipeline networks are compared to obtain a minimum installation cost. The 1000km pipeline is divided into a number of short sections to calculate the pressure drop along the pipeline length. The design pressure is considered according to the 600 flange rating, 1,350 Psig and 90% of the design pressure is envisaged for the maximum operating pressure for the pipeline design.
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Introduction
The Trans –Sahara Transmission Gas Pipeline is poised to occupy a more prominent place in the global energy balance, coupled with other renewable energy sources, natural gas is an energy source of choice for the development of Africa and offers a vehicle for its integration with the world economy [6]. The Nigerian Economic Sustainability and the expected benefits of gas reserves are estimated at about 5 trillion cubic meters – equal to roughly ten years of consumption of the EU [6]. In light of growing demand factors from Europe due to the depletion of European gas fields, and the need for an alternative to Russian gas, the demand from Europe is likely to remain high. Hence, the Trans- Sahara Transmission Gas Pipeline (TSGP) would enable these African economies to access a new market for their gas reserves, thereby increasing their incomes [6].
Furthermore, the Nigeria –Algeria pipeline is also called Trans- Sahara Transmission Gas Pipeline that would contribute to eliminating natural gas flaring in Nigeria [6]. The TSGP has the critical advantage of supplying gas to Northern Nigeria, Niger, Southern Algeria, as well as Burkina Faso, and Southern Mali which are currently affected by high energy prices and desertification [6]. The TSGP between Algeria and Nigeria will recover flared gas in Nigeria and bring it through a pipeline toward the European market. This gas is burnt currently in flares and hence, represents a loss of energy equivalent to 220.000 barrels/day for Nigeria and thus has grave consequences on the environment [6].
The TSGP will provide power to the areas, thereby contributing notably to the revival of those areas, where there exists water and fertile land. Also, it will enable several countries in the region to access electricity [6]. The major difficulty in the use of natural gas is transportation and storage because of its low density.
Natural gas which was once an almost embarrassing and unwanted by-product or more correctly a co-production of crude oil production now provides about 1/5th of the entire world primary energy requirement [3]. This remarkable development has taken place in only a few years with increased availability of the gas resources of the country and the construction of long distance, large diameter steel pipeline which has brought these sample supplies of gaseous fuel to domestic, commercial and industrial users many miles away from the field themselves [3].
Conclusion
In remote areas operating compressor stations can be difficult so they can either be operated unmanned or possibly relocated slightly to place them in a more accessible location. It can be observed that, as the diameter of a pipe increases the number of compressor stations decreases. In the pipeline costs, material costs are proportional to pipeline diameter, while construction and design costs are approximately constant. Therefore minimising the pipeline diameter will reduce the pipeline total installed cost by a significant amount. As the 1524 mm pipe diameter has very small compressor station cost but it has very high pipeline cost. There are very few manufacturers who can supply 1524 mm diameter pipelines and, therefore this size pipeline is disproportionately expensive. This is due to smaller diameter have more pressure drop than larger diameter pipelines, so for the same compression power the gas can be transported for longer distance with larger diameter pipe than smaller diameter pipes. From the figure 5.1, it can be observed that the cost of compressor for the pressure 500 psia and 600 psia is high, so instead of these compressors, the compressor station spacing is altered, and 700 psia pressure compressors can be replaced to reduce the compressor cost