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A Supercritical Showcase

Siàƒ¢n Green

Patnow power plant is being upgraded as part of a programme to modernize Poland’s PAK group of power plants. When it is commissioned in 2004, Patnow II will be one of the lowest cost and cleanest power generators in the country.

In 2001, Poland’s Elektrim-Megadex embarked on the modernization of the Patnow power plant. By mid-2004, the new plant will be commissioned, and, complete with supercritical technology, is to be one of the most competitive plants in the newly liberalized Polish power market.

The modernization of Patnow is part of a wider modernization programme of Zespàƒ³l Elektrowni Patnow Adamàƒ³w Konin SA (ZE PAK), a group of three brown coal fired power plants in Poland with a total power generation capacity of 2738 MW. The modernization will help to improve the efficiency of the three plants and ensure their compliance to European Union environmental standards as Poland prepares for accession.

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The Patnow project is the first stage of the modernization programme, and involves the construction of a 460 MW supercritical unit in place of two existing 200 MW units at the Patnow complex, located some 200 km west of Warsaw. The new unit à‚— Patnow II à‚— will be commissioned in August 2004.

ZE PAK is 38.46 per cent owned by Polish industrial group Elektrim following privatization of the three power plants in 1999. ZE PAK accounts for around ten per cent of generation in Poland, and its location in the north-central region of Poland near large cities like Poznan, Bydgoszcz, Plock and Wloclawek, means that it is well-positioned to be a major player as the liberalized market develops.

Under an agreement with the State Treasury, Elektrim pledged to modernize the PAK power plants, and in 2000 began work on plans for Patnow. In September 2000, the company signed a 20-year power purchase agreement with Polish power grid company PSE for the offtake of power from Patnow II, and in early 2001 it awarded its subsidiary Elektrim-Megadex SA a fixed-price turnkey contract for the project’s engineering, procurement and construction (EPC).

In May 2001, Elektrim Megadex awarded a consortium of Alstom and Rafako a contract for the supply of the major power generation and environmental control equipment to the project. Boiler engineering company Rafako is to design, construct, erect and commission a flue gas desulphurization plant for Patnow II, while Alstom will supply a 460 MW supercritical steam turbine generator set, a supercritical boiler, and other equipment including mills, firing equipment, pumps, condensers and heat exchangers. The company will also be responsible for the engineering, erection and commissioning of the boiler and turbine island.

Financing the future

The modernization of Patnow is being financed under a long-term credit agreement between Patnow II Power Plant and a consortium of banks comprising the European Bank for Reconstruction and Development, Citibank NA and Westdeutsche Landesbank Girozentrale. The agreement includes $392 million of credit extended for a period of 14 years and secured by the 20-year power purchase agreement with PSE.

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“Providing funding for the investment will enable the construction of a very modern power unit of the highest efficiency in Poland,” commented PAK on announcing the financing in 2001. “The plant will be a showcase for state-of-the-art technology in the Polish power sector.”

The credit provides 75 per cent of the project’s funding; the remaining 25 per cent is being provided by ZE PAK funds obtained through a sale of capital to Elektrim in March 2000.

Advanced design

Patnow II will be equipped with a supercritical Alstom boiler and steam turbine and will have a gross generation capacity of 464 MW (446 MW net), and a thermal efficiency of approximately 44 per cent.

Patnow II will be fired by brown coal, and is expected to use approximately 3.1 million ton per year. Brown coal will be supplied by Konin Brown Coal Mine under a 20-year fuel supply agreement, and will be sourced from an open cast mine 8 km from the plant. The coal will be transported to the plant using a rail link to the existing unloading and conveying system at the Patnow II complex. The unloading and conveying system has adequate capacity for both Patnow I and II plants, and so will not require expansion or upgrade.

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Patnow II will also share other infrastructure facilities with the existing Patnow power plant, including the coal handling system, the cooling water system, post combustion waste disposal and process water supply. These facilities will be provided by ZE PAK under a shared facilities agreement.

As consortium leader, Alstom is designing and constructing a supercritical pulverized coal fired boiler for Patnow. Supercritical technology provides high plant efficiency and therefore economic use of fuel and lower CO2 emissions compared to conventional coal fired plant.

The boiler will be a spiral wall, tower design and will use advanced once-through technology. It will be equipped with Alstom’s low-emissions firing system to reduce NOx levels to below current environmental requirements. It will use eight beater wheel mills and incorporate four reheat safety valves and two high pressure bypass valves. Light fuel oil will be the ignition fuel.

The boiler operating parameters are as follows: main steam flow, 1315 t/h (365 kg/s); superheater outlet steam pressure, 266 bar; superheater steam temperature, 544à‚°C; reheat steam flow, 1210 t/h (336 kg/s); reheat steam pressure 53 bar; reheat steam temperature, 568à‚°C, reheat inlet temperature, 308à‚°C. NOx flue gas emission levels at the stack will be less than 350 mg/Nm3 (170 ppm).

Efficiency and environmental protection are now key issues in the Polish power sector as the country prepares for EU accession
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The boiler will burn domestic lignite with a gross calorific value of between 9.2 MJ/kG and 11.6 MJ/kg, a moisture content of 48.8-55 per cent, and an ash content of 5-15 per cent.

Alstom will also supply a three-pressure condensing steam turbine with an electrical output of 476 MWe and a condensing pressure of 3.43 kPa. The steam turbine operating parameters are as follows: live steam pressure, 258 bar, live steam temperature, 540à‚°C, live steam mass flow, 365.3 kg/s, reheat steam pressure, 50.1 bar, reheat steam temperature, 565à‚°C.

Clean operation

Patnow II will be fitted with a flue gas desulphurization system and an electrostatic precipitator to achieve a sulphur dioxide precipitation efficiency of around 95 per cent and a dust removal efficiency of approximately 99 per cent. Rafako is to supply the FGD plant of the wet lime type, which works by washing the flue gas with quicklime or an aqueous limestone suspension. The value of Rafako’s contract is €8.25 million.

Patnow II will be connected to the national grid via 220 kV overhead lines and an existing substation. The plant will be operated by ZE PAK personnel as a baseload plant. ZE PAK will be responsible for plant maintenance.

A competitive future

Due to the use of supercritical technology and emission control technology, Patnow II will be one of the most efficient and cleanest power plants in Poland. Other key advantages of Patnow II include:

  • Due to its low fuel and fuel transportation costs, Patnow II will have one of the lowest power generation costs of any plant in Poland. Konin Brown Coal Mine has 40 years of brown coal reserves to supply both Patnow II and ZE PAK.
  • In Poland, lignite has a cost advantage over hard coal of approximately 30 per cent. The project’s supercritical technology (about three per cent more efficient than conventional coal-fired technology) and low variable costs should ensure base load dispatch and ability to compete in the liberalized market.
  • Patnow II will benefit from relatively low capital investment costs due to its shared infrastructure facilities with the existing Patnow power plant.
  • Elektrim Megadex, the EPC contractor, is experienced in the Polish market, both in terms of obtaining permits and in ensuring construction completion on time and within budget frameworks. It will be supported by experienced subcontractors with whom it has been engaged in similar projects and under a similar contractual structure.

The project is proceeding to schedule, according to Alstom, with process engineering 80 per cent complete and the procurement of the main equipment complete. Work on the turbine foundation substructure is due to start in August 2002, when the delivery and erection of the condenser is also due to take place. Turbine unloading at site is scheduled for December 2002-April 2003, while boiler unloading will take place in February-March 2003. Commissioning is due to start in November 2003.