460 MWe Supercritical OTU CFB Boiler Łagisza Power PlantPOLAND

Since our 1 10 MW e Tri-State Nucla power project in the U.S. in 1987, FW continued the development and advancement of our CFB technology. Over the years, FW has steadily increased unit size and has integrated advanced f eld-proven design features into our CFB technology for use in our projects around the world.

In 2001 FW made a signi f cant advancement in our technology with the 2 x 300 MW e units for the Jacksonville Energy Authority. Over the period 1998-2008 FW has, in addition to the Jacksonville units, delivered six CFB units totaling nearly 1500 MWe for the largest CFB repowering project ever in history - the Turów project in Poland.

FW’s success in becoming the world leader in the supply of CFB boilers around the world has come from a track record of satisfying our clients’ reliability, environmental, and ef f ciency goals. Using FW’ s innovative technology and global resources, FW has become the leader in converting economical solid fuels into valuable steam and power . Through our experience of supplying over 480 f uidized bed units to industrial and utility customers worldwide, we have steadily scaled-up and improved our technology .

FW’s leadership in the pioneering of CFB technology can be seen in our award for the Łagisza project in Poland, which brings a double f rst to the utility power industry - the world’s f rst supercritical CFB boiler and the world’s largest single CFB unit, rated at 460 MWe.

With FW’ s continued commitment to the CFB technology for the long-term, we are developing Flexi-Burn TM technology which will allow the FW CFB to generate a CO 2 rich f ue gas and be part of a practical CO 2 capture and storage solution capable of reducing CFB CO 2 emissions by over 90%.

FW’s technical expertise allows our CFB units to be capable of f ring nearly all solid fuels - including waste products that otherwise would have been land- f lled - while maintaining the lowest levels of emissions, and the highest equipment reliability and ef f ciency. FW’ s fuel experience is unmatched in the industry and the f exibility of our CFB boiler to burn even the lowest quality of fuels gives plant owners the f exibility to source fuel from multiple sources improving their fuel supply security while taking advantage of fuel prices and market conditions.

Pioneering CFB Technology

The new 460 MW e unit will replace the old power blocks of the Łagisza power plant. The existing blocks were erected in the 1960’ s and consist of seven units (110-125 MWe each). Two of them will be shut down after the new 460 MWe unit is commissioned. The new boiler will be built adjacent to the old boilers and many of the existing plant systems like coal handling and water treatment will be renovated and utilized for the new CFB unit.

The FW delivery is for the turnkey boiler island including engineering and design, civil works and foundations for the boiler, boiler house enclosure with steel structures, boiler pressure parts, auxiliary equipment, main steam and reheat steam piping to turbine, coal bunkers and fuel feeding equipment, electrostatic precipitator and cold end f ue gas heat recovery system, erection, construction, start-up, and commissioning.

The boiler design for Łagisza is based on well proven FW CFB technology . It utilizes theexperience of over 350 reference units.

The Łagisza design utilizes BENSON vertical-tube, supercritical once-through steam technology for the evaporator steam circuit under license from Siemens AG, Germany. CFB technology with its low and uniform furnace heat f uxes is well suited for the BENSON technology providing a stable operation of the boiler also during load changes andabnormal operation conditions.

The plant net ef f ciency is naturally dictated by the selected steam parameters, steam cycle conf guration, cooling tower conditions and boiler ef f ciency. In the Łagisza design the boiler eff ciency is further improved by a f ue gas heat recovery system, which cools the f ue gases down to 85 OC thus improving the plant net ef f ciency. The calculated net plant ef f ciency for Łagisza is 43.3 % (based on the fuel’ s lower heating value) and net power output is 439 MW e.

The main fuel for the boiler is bituminous coal. The source of fuel consists of ten local coal mines with a wide range of coal parameters, proving once more the fuel f exibility of the CFB technology .

The selected steam pressure and temperature are proven in other supercritical units and conventional boiler steel materials can be used.

The emission requirements for the Łagisza boiler are according to European Union directive for Large Combustion Plants. The emissions for sulfur dioxide are controlled with limestone feeding into the furnace. The nitrogen oxide emissions are controlled with low combustion temperature and staged combustion. There are also provisions made fora simple ammonia injection system (SNCR), however that is not required on design coals. Particulate emissions are controlled by electrostatic precipitator .

Project Basis

Limestone silo

Bottom ash silo

Low pressureby-pass economiser ID fans

Electrostatic precipitator

Heat recovery areaBed material silo

Coal silos

Solid separators

Flue gas cooler

SA Fans

Electrostatic precipitator

Fly ash silo

SA Fans

Recirculation gas fan

Solid separators

Limestone silo

Coal silos

The feedwater enters the boiler at a temperature of 290 OC for preheating in an economizer . Thereafter water is divided to the enclosure walls of the INTREX™ f uidized bed heat exchangers and further to distribution headers of the evaporator (furnace) walls. The water is heated in the evaporator wall tubes and eventually converted to superheated steam before the evaporator outlet.

Dry steam from the water/steam separators is led to the furnace roof which is the f rst part of the superheating system. After the furnace roof, steam is taken to the superheater support tubes, walls of the convection pass and coils of the convective superheater I. Superheater II is located in the upper furnace in areas where the solids densities are low and its lower ends are protected against any possible erosion.

After superheater II, the steam is divided into eight parallel solids separators that form the superheater III. The separator walls are formed of gas tight membrane walls and they are covered with a thin refractory lining with high heat conductivity .

Water and Steam Circuitry

Final superheating is performed in superheater IV located in four INTREX™ superheaters at the one side of the furnace.

The main steam temperature is controlled with a two stage feedwater spray as well as by adjusting fuel feeding. Steam after the high pressure turbine is brought back to the boiler for reheating. The f rst stage reheater is located in the convection pass. The reheater I (RH I) is equipped with a steam side bypass which is used for reheat steam temperature control. The f nal reheater stage is located in INTREX™ heat exchanger similar to the f nal superheater.

There are eight solids separators arranged in parallel, four separators on two opposite furnace walls.

The advanced separator inlet design with it’ s tall and narrow shape provides a uniform f ow of f ue gas and solids avoiding high local velocities. This results in equal collection ef f ciency as the best conventional cyclones with considerably lower pressure loss.

Solids Separator Design

The plant is operated with sliding steam pressure so the boiler pressure is following the turbine load.

The f ue gas side of the furnace design for the Łagisza CFB is based on extensive analysis of the fuels and limestone that are going to be used. These have given the required data for the design models to make predictions for circulating material particle size distribution, solids densities and f nally the heat transfer with gas temperatures.

Fuel feeding is arranged on the long walls of the furnace. Secondary air is introduced at three elevations to provide staged combustion for minimizing the NO x emissions.

INTREX™ is a f uidized bed heat exchanger extracting heat from the hot circulating bed material that is collected in the solid separators. Additional bed material is taken to INTREX™ chambers directly from the lower part of the furnace. This provides a suf f cient amount of bed material at wide load range. A unique feature of the INTREX™ superheater is its ability to control the heat transfer by changing the f uidization velocities. This special capability is utilized for example during load changes to trim the steam temperatures and to control reheat steam temperature. Also in case of fuels having high chlorine contents INTREX™ superheater provides enhanced protection against corrosion.

The Łagisza boiler design incorporates altogether eight INTREX™ heat exchangers, one for each solids separator . W ater cooled casing of the INTREX™ surfaces allows the integration of the INTREX™ casings to the furnace thus eliminating expansion joints and minimizing distances to transfer hot solids. Controlling of the f ow of hot solids is done only with f uidization, therefore no valves or other mechanical devices are required.

The f ue gas Heat Recovery System (HRS) improves the boiler and power plant ef f ciency by decreasing the f ue gas temperature down to 85‹ OC. The system recovers heat from the f ue gases which results in an improvement in total plant eff ciency.

The HRS is operating in the clean gas after the ESP and ID fans. The cooling of the f ue gas takes place in a heat exchanger made of PF-plastic tubing to avoid corrosion problems. After the HRS, the f ue gas is conducted to the cooling tower via glass f ber duct.

A primary water circuit transfers the recovered heat to the combustion air system and heat is transferred to both primary and secondary air. As the combustion air temperature before the rotary air preheater is increased, the air f ow is not able to absorb all the heat available from the f ue gases. Therefore part of the f ue gases is conducted to a separate low-pressure bypass economizer where the heat from the f ue gases is used for heating of the main condensate.

Furnace Design INTREX™ Heat Exchanger Design

Flue Gas Heat Recovery System

Windbox

INTREX™

Otwory cyrkulacjiwewnętrznej

Kanałprzerzutowy

Return l eg

Internal circulationopenings

SuperheaterLift leg

Wall seal

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