Engine & Turbine Technology
Under contracts totalling more than US$14m (€10m), GE is upgrading four GE Frame 9E gas turbines that were installed at the KAPCO plant nearly 22 years ago. Te upgrade of the first unit has been completed, and the upgrades for the remaining three machines are scheduled for completion by late 2011. When the total project is completed, overall plant net combined- cycle efficiency will increase, while the output of each gas turbine will increase by 3MW, for a plant total of 12MW – enough additional power for 800 000 homes. “Our goal was to improve the gas turbine heat rate to get increased plant efficiency, and GE offered the best solution to meet our requirements,” said Naeem Ahmad Tariq, senior manager maintenance of KAPCO. “Te fuel savings that will be realised due to the higher efficiency and the additional output will generate additional revenue of US$1.5m/y (€1.1m) for each gas turbine.” Te increased plant output will help KAPCO
respond to Pakistan’s growing electricity requirements. According to government estimates, the gap between supply and demand during peak load periods is 5GW, and the country’s annual average growth in power demand is 8 per cent.
A first in Russia
Alstom has commissioned unit 8 of the TPP-26 cogeneration gas combined cycle power plant in Moscow, in Russia, on behalf of its client OJSC Mosenergo, Russia’s largest fossil fuel based power generating company. With an efficiency of 59%, the gas fired cogeneration combined cycle unit will have the highest efficiency of any combined cycle power plant in Russia, while the use of surplus steam for district heating will bring the plant’s overall fuel utilisation to well over 85 per cent.
Te integration of unit 8, designed to produce
420MW of electrical power and up to 265 MW of district heating, will bring total plant output up to 1830 MW making the TPP-26 plant a pivotal contributor to the Russian grid as well as a valuable source of district heating. In 2007, Alstom was chosen by Mosenergo to be the first foreign enterprise to build a combined cycle plant in Russia on an EPC basis, making Mosenergo Moscow TPP-26 unit 8 Russia’s first turnkey energy project to be handed to a non-Russian company. Mosenergo is a subsidiary of Gazprom, the largest extractor of natural gas in the world and the largest Russian company.
Plant modernisation Meanwhile Alstom’s Termal Services unit in Hungary has successfully completed modernisation of unit 8 of the Dunamenti gas-fired power plant owned by Gaz de France Suez.
Te modernisation project awarded to Alstom in 2008 included the retrofit and upgrade of the complete steam turbine island and the associated balance of plant at unit 8 of the plant to match the new steam data following the installation of a gas turbine from another vendor. Te project started in April 2009 and has been successfully completed with the commissioning of the retrofitted unit 8 in July this year. It has contributed to the increased output of unit
8 from 215MW to above 400MW and a jump in efficiency from 36-57 per cent. Te efficiency increase also results in a substantial reduction of carbon dioxide emissions from the plant. Tis project was a brown field investment, whereby the steam turbine island unit no 8 was modernised by using the power plant’s existing infrastructure. Te six conventional type 215MW steam turbines at the plant including the related condensers and feedwater heaters were originally supplied by Alstom companies.
Steam atomisation for steam conditioning T
he direct steam converting valve - steam atomisation (DSCV- SA) from SPX is designed for
unprecedented operational reliability and eliminates potential risks associated with substandard designs during plant start-up, shutdown and turbine trips. As a result, the DSCV-SA is at the forefront of modern thermodynamic engineering in steam conditioning. Key to the DSCV-SA’s performance are a number of novel technical innovations developed by SPX following extensive consultation with customers in the power generation sector. The first of these is high-pressure
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balance. Unlike conventional turbine by-pass valves, the DSCV-SA is designed to use high-pressure balance rather than low-pressure balance. This eliminates risk of wear, damage or breakage relating to piston rings and balancing systems, which are a major problem with traditional valves. Another innovation associated with
the DSCV-SA is steam atomisation. This technology has significant benefits over mechanically spraying the cooling water via nozzles. For example, the pre-heated cooling
water significantly accelerates the evaporation and desuperheating process. Equally important is the finely atomised
incoming cooling water. Very fine atomisation produces extremely small water droplet sizes with a vastly increased surface area to promote rapid heat transfer. The atomised, pre-heated water is
introduced via a combining tube where it is atomised and then passed through a converging/diverging venturi throat section. The hot atomised water exits the atomising head and is rapidly evaporated, cooling the main steam flow. Because this method of water introduction does not rely on surrounding steam velocity or turbulence for effective mixing, it gives very high turndowns - generally in excess of 100:1. ●
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