Assembling power

The world's largest barge-mounted power plant will be operational in Pakistan by 1999

Published: Monday 30 June 1997

-- (Credit: Sanjay Ghosh)A 450 MEGAWATT barge-mounted combined cycle power plant is scheduled to start operating in Pakistan by 1999. The plant, which is believed to be the world's largest barge-mounted power plant, will be constructed in the us on six barges and shipped halfway around the world to Port Qasim in Karachi.

The logistics of building a power plant on a barge and then shipping it halfway around the world may appear prohibitive. However, there is an increasing need for rapidly delivered, packaged power plants to anchor industrial and urban development. Platform or barge mounted power plants'(BMPPS) are highly engineered power plants mounted on barges and other marine platforms designed around utility-grade simple and combined-cycle generating equipment.

One advantage with BMPPS is that projects are completed at faster rate. In the case of this project, it will be delivered and commissioned within 28 months. As the equipment and the barges are constructed in a controlled, factory environment - rather than at a difficult, remote site - the project will benefit from better quality and low costs. There is a standard configuration equipment to meet specific customer needs and save time. Also, BMPPs are easier to finance than many landbased power plants. In certain cases, the BMPPS are excellent candidates for leasing. A project of this nature may qualify for special maritime financing pro- grammes, barges are essentially ships. Certain projects may qualify for financing from various export credit agencies.

Another advantage with BMPPS is that they can be easily relocated. The power plant is moved to the site once the construction is complete. It can then be moved to a new site it and when required. BMPPS can also be modularised for staged installation, expansion and conversion. For example, the plant can begin operating as a simple cycle and then be phased to a combined cycle plant when the remaining barges and equipment are completed.

The barges are designed as intermediate and baseload plants - operating for about 5,000 hours per year. They are expected to operate with a 60 per cent capacity factor. The use of non -polluting fuel, LPG, ensures that the facility will meet all World Bank air pollution stadards. The cooling towers will minimise thermal discharge to the surrounding waterways. Besides, as a precaution against water pollution, the fuel storage systems are constructed on land and not on the barges.

Besides being the largest BMPP in the world, the Port Qasim plant is expected to be one of the most reliable power generation facilities in Pakistan. There will be a total of six barges, each 27.4 rn by 82.3 m with a depth of 4.9 m. To achieve the 25-year design life, the hull design calls for additional steel corrosion allowance, a point and coating system, a sacrificial anode system, and a preventive maintenance programme. The addition of framing and support steel for the equipment loads and increased hull steel thickness for corrosion allowance results in a hull that far exceeds 11ormal. barge requirements. Since few ships in the world can carry barges of this size on its deck, the delivery will be staged after the barges are completed.

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