Foster Wheeler is building a new coal fired power plant at Lagisza in Poland featuring the world’s first supercritical CFB boiler and Metso Automation has been handed the challenge of automating this complex and unique plant.

Staff Report

The Lagisza power plant in southern Poland is in the spotlight of the power engineering world as work commences on a unique power generation project. A new 460 MW power plant project is taking off that will incorporate the world’s largest circulating fluidized bed (CFB) boiler. Supplied by Foster Wheeler, this boiler will also be the world’s first supercritical CFB unit. Automation of a plant of this complexity presents a further challenge – one that is being met by Finland’s Metso Automation.

The Lagisza power station is a hard-coal fuelled conventional thermal power plant made up of six blocks plus a heat distribution center. The existing plant, equipped with two Babcock & Wilcox and four Rafako boilers, two AEI Metropolitan Wickers and four TK 120 turbines supplied by Zamech was built in 1963 and supplies power to the national energy system.

Today, Lagisza consists of six 120 MW units with an installed electrical capacity of 720 MWe. Owned by one of Poland’s largest utility companies Poludniowy Koncern Energetyczny (PKE), it generates around 2.2 per cent of the national electrical energy production. Additionally, the plant supplies heat for district heating and also to neighbouring industrial plants with a 332 MWt capacity.

PKE operates six power plants and two CHP plants. With a total power generation capacity of 4953 MW, PKE has about 14 per cent of the market share in Poland’s electrical energy production and it is the second largest electricity generator in Poland. With a heat capacity of 2400 MWt, PKE has a 16 per cent share in the local heat market.

PKE modernization

The modernization project at Lagisza was first announced in 2003. In January 2006 PKE gave the go-ahead to Foster Wheeler to take over the construction site and design, supply and erect the CFB boiler island. Engineers from Alstom Power, the turbine supplier arrived on site in mid February and foundation work and chimney cooler works began in April. Around 1000 people will be employed at the construction site at the peak time. The start-up for the new 460 MW unit is scheduled for the second quarter of 2009. It will be built alongside PKE’s existing 720 MW power station at Lagisza.

PKE S.A. Lagisza power plant in southern Poland will be in the spotlight of the power engineering world
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The €500 million ($617 million) project is part of an on-going programme by PKE to replace outdated capacity with modern, high-efficiency and environmentally friendly technologies across its generation fleet. The new Lagisza unit is being financed by PKE, along with an ecology subsidy and through a special emission bond. The new hard-coal fired Lagisza plant will be able to use biofuel for up to ten per cent of the overall fuel load in terms of chemical energy. The new block will burn 1.2 million tonnes of coal a year.

Technologies for solid fuels

Foster Wheeler will supply the new plant with a circulating fluidized bed boiler island, and has already carried out some activities, including engineering and procurement services as well as placing purchase orders for pressure parts materials. For Foster Wheeler the project marks a crucial step forward in bringing its CFB boiler technology to utility scale. Integrating the supercritical steam cycle and once-through technology into CFB technology will provide PKE with a unique engineering solution that aims at the clean and efficient combustion of solid fuel.

“Achieving this improvement in a single step is a major achievement,” says Timo Kauranen, president and CEO of Foster Wheeler Energia, the Finnish Foster Wheeler subsidiary responsible for the project. “An equivalent increase in fuel efficiency has typically taken up to ten years of cumulative development to achieve. By incorporating the supercritical steam process with Foster Wheeler’s world-leading technology, we will be offering PKE the very best in solid fuel combustion. Our modular design approach will also enable us to offer even larger units of the same type in future.”

The high pressure and temperature enabled by the supercritical steam cycle will cause fewer CO2 peaks and lower SOx emission levels, without the need to invest in a separate desulphurization plant. With this change Lagisza aims to meet the demands of legislation and meet the requirements of the EU’s new Large Combustion Plant directive, thereby avoiding the heavy penalties levied on excessive emissions. Besides the environmental benefits, the plant also strives for improved production efficiency and increased capacity. Thanks to the supercritical steam parameters and its advanced overall design, the plant will use some five per cent less fuel per GWh of electricity generated than conventional drum-based boilers. Total plant efficiency will be in excess of 43 per cent.

When finished, the Lagisza boiler plant is expected to be the leading example of a cost-effective twenty-first century environmental solution, which helps the power generating industry to reap the full benefits from their domestic coal reserves.

Automation challenge

Metso Automation has been selected to provide the new plant with a complete Distributed Control System (DCS) based on its metsoDNA technology. In addition to the basic automation system, the delivery includes superior controls with a performance monitoring application, a burner management system, as well as power unit safety and interlocking systems.

The system will contain approximately 20 000 I/Os (inputs/outputs), seven process stations and three operator stations with three monitors and three large video screens for operator interfaces – covering all boiler and turbine processes.

Mariusz Sloma, managing director of Metso Automation Polska sees the Lagisza plant as a thrilling example of utilizing new technologies for all conventional power plants
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“The boiler island in this double world-first also makes the automation system delivery demanding and unique,” says Mariusz Sloma, managing director of Metso Automation Polska Sp.z.o.o.

“A system like this is not based on given source data, but designed together with the boiler concept, in seamless cooperation with the other experts. Our strength is the long and deep experience in power plant automation, so we can cooperate in expert teams and take on such a demanding challenge,” says Sloma.

Specialized FBB tools

“We have supplied over 700 power plant automation systems worldwide, including over 100 fluidized bed boilers (FBB) automation applications. Based on that experience we can provide FBB with specialized control applications for combustion optimization, and achieve higher boiler efficiency with less emissions,” says Sloma.

“When burning different fuels in the FBB/CFB boiler it is vital that the boiler knows what fuel or calorific value is combusted. A special control application, called a fuel power compensator, compensates for disturbances in the fuel feed, and stabilizes the combustion and steam production, for instance when the fuel quality or the fuel flow changes,” Sloma explains. “This supports faster fuel mixing, quicker adaptation to heat consumption and electricity price changes, and of course use of less expensive, lower quality fuels.” Metso Automation has extensive experience from the world’s largest biomass fired CFB Boiler (240 MW in Alholmenskraft, Finland) and is currently involved in Poland in a project with biomass co-firing in fluidized bed boilers in the Siersza power plant/PKE (CFB 2 x 153 MW), which will result in implementing a fuel power compensator application this year.

The double world’s first: 460 MW CFB based supercritical unit by Foster Wheeler
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“Another typical problem in FBB/CFB combustion with a varying fuel mix is the fatigue and stress on boiler components. The boiler life monitoring application calculates, stores and displays the factors indicating the operating stresses and normal wear of critical boiler components, enabling predictive maintenance planning and minimizing costly repair shutdowns,” says Sloma.

Experience counts

The start-up of the Lagisza project is a much-anticipated event. After the deal was closed with Foster Wheeler in 2003, the automation supplier was chosen directly by PKE through a public tendering process.

“This process itself can be long and complicated,” Sloma describes. “But the one who fulfils the given criteria in the best way wins. Many things counted in Metso’s favour, such as reliability through redundancies, low spare part costs, low life cycle costs and long experience in power plant automation. Metso has recently automated three CFB coal-fired boilers in Poland, too, so this is not a virgin market for us,” he points out.

“During the last few years (2002-2004), our particular experience in CFB technology enabled us to provide performance monitoring applications for two CFB based units (in Siersza power plant/PKE) with on-line performance monitoring and operation management, off-line performance monitoring “with reconciliation of substance and energy balances”, as well as monitoring of “operation point deviation”. Implementation of the reconciliation method was pioneering work at that plant, which we developed together with the Silesian University of Technology Institute of Thermal Technology to improve the accuracy of performance calculations and measurements through substance and energy balances. Operation point deviation monitoring involves monitoring the change in plant efficiency due to deviations from the design values of steam pressures and temperatures, flue gas temperatures, flue gas O2 and CO concentrations, and condenser pressure”, Sloma explains.

As for the success of the Lagisza project, Mariusz Sloma sees the commitment and honest cooperation between the Metso, Foster Wheeler and PKE expert teams as the most important factor. “We will work hand-in-hand to make sure of the future start-up in Lagisza,” he concludes.