Revue6-EN.pdf

COGENERATION LARGE SCALE

ITEBE

Wärtsilä

« Small Scale » Bio energy for the Future Jussi Heikkinen, Vice President of Wärtsilä Finland, Power Plants, BioPower

Within the international development of bioenergies, Wärstsilä has found a place. This Finnish company, that was originally working in the marine industry, has diversified its activities in this sector where it now offers innovative technologies. Facing the future, it is now trying to enlarge its role in this field.

WÄRTSILÄ FINLAND OY

Finland

Käkikosken Saha Oy 3,5 MW power station using BioGrate technology.

Fuels : bark, sawdust, wood chips.

lobally, natural biomass fuels and combustible fuels recovered from municipal waste are available in huge quantities. The Finnish power company Wärtsilä, for its part, has identified a particular sector within bio energy in which to establish itself wi th a v i e w to future g row th .

Through the acquisition of Sermet Oy Wärtsilä, BioPower is already one of

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the leading suppliers of boilers for biomass fuels in the Nordic countries.

There is a strong political will worldwide to make increasing use of renewable energy. Finnish subsidiaries of Kvaerner and Foster Wheeler have established themselves as global leaders at the large scale end of the market, based on the wealth of experience and expertise gained from working with the environmentally-conscious Finnish forest industry. Finland is in the forefront of biomass combustion know-how in the world.

Wärtsilä focuses on the smaller end of the bio energy market. The Finnish power company is initially offering modular boiler plants in the range of 2-25 MWth and power plants in the range of 1-5 MWe, burning woodbased fuels. This strategy was chosen due to the exponentially larger availability of suitable fuel sources. Later

Wärtsilä may expand both the fuel spectrum and power range.

“There are several local equipment suppliers in this market, but none of them has the capability to supply biomass power plants globally”, explains Mr Jussi Heikkinen, Vice President, Wärtsilä BioPower ; “We have an international sales and service network and strong capabilities in product modularisation and project management, backed by the knowhow forged in the highly developed and competitive Nordic bio energy market.”

THE MARKET FOR RENEWABLE ENERGY The global biomass-fired boiler and power plant market is forecast to grow in many regions of the world.

Smaller bio-energy plants are typically made for industrial applications such as sawmills, where the heat is used for drying timber, and for general heating purposes. Large plants are commonly built when there is access to a large bio fuel supply, as is the case at pulp and paper mills or sugar mills. Large projects are typi-

COGENERATION LARGE SCALE cally CHP plants while the smaller ones have been heat boilers.

The future market is being driven by general concern about the environment and global warming. Approximately 70 % of renewable energy sources (RES) are based on biomass.

Major international programmes which set out frameworks for this kind of development include the Kyoto Agreement and the recent European Union (EU) White Paper which states that EU electricity gen-

WÄRTSILÄ FINLAND OY

Sermet Oy boiler with a rotary grid allowing stable and constant combustion for moisture content up to 65 %.

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eration capacity based on renewable fuels shall increase from 20 TWh to 230 TWh by 2010 !

In the same timeframe, Europe’s total usage of renewable energy sources (RES) is to be doubled, and the share of bio energy must be trebled. The E u ro p e a n Par l iam e n t is s o o n expected to pass a directive setting targets for bio-electricity production for individual EU nations. Incentives such as tax benefits and subsidies for biomass-produced energy are driving a variety of bio energy developments in Europe. Europe offers the most obvious market for small-scale bio power in the short term.

The EU is working to assist the increase in utilisation of mainly biomass-based RES. A characteristic of

this market is that some fuel will come from refuse derived fuel (RDF), i.e. selected municipal waste, which is regarded as a bio fuel. The growth of an international bio fuel trade will help in stabilising bio fuel prices and availability. Green certificates and emission trading will also assist in financing bio power projects.

There is a huge market potential in tropical countries, which have huge biomass resources suitable for energy production. But the less-developed countries cannot provide similar subsidy structures as the richer EU and this limits the development of these markets to some extent.

NEW TECHNOLOGY FROM WÄRTSILÄ One drawback to the advance of bio power at the smaller-scale has traditionally been that existing technologies have problems with thorough combustion of wet and even icy fuels in periods of cold weather such as is experienced in the Nordic countries during winter. Sermet Oy has worked on this challenge since the early 90s, with the first 4MWth installation using advanced BioGrate technology commencing operation in 1994 at a Finnish sawmill.

Currently, the two main customer groups for BioGrate technology are Nordic sawmills and municipal energy (district heating) companies.

To date, over 60 BioGrate installations have been delivered to Scandinavia, Baltic countries, Russia, Canada and France. For this existing customer base, bio boiler and bio power plants using BioGrate technology designed to cope with hard climate conditions and wet fuels provide a most competitive solution ; future developments of BioGrate technology will build on this success to address operation in other environments.

The BioGrate solution is based on a rotating conical grate. In the primary combustion chamber, fuel is fed upwards on to the rotating grate bars through a channel in the centre of the chamber. Combustion is stable, because the fresh fuel entering in the centre of the rotating conical grate does not disturb the surrounding burning fuel bed and the rotating grate bars control the thickness of the fuel layer.

As the fresh fuel flows in a controlled fashion down to the combustion grates it is dried by heat radiation from burning gas and the refractory

COGENERATION LARGE SCALE

WÄRTSILÄ FINLAND OY

Lisalmen Sahat Oy, with on the right the 10 MWth, 0,88 MWe cogeneration power station and on the left the 3,5 MWth thermal station. Fuels : bark, sawdust, wood chips.

FLASH Combined Heat and Power -law The law for the maintenance, modernization and development of combined heat and power from the 19th of March, 2002 (Kraft-WärmeKopplungsgesetz) was changed on the 22nd of March, 2002 in the

surfaces lining the primary combustion chamber. The further the fuel rolls from the centre, the more combustion takes place ; when the fuel reaches the outer edge of the grate it has been completely combusted and only ash is left. This method – which requires neither fuel pre-drying nor support fuel – provides a very stable constant combustion process for fuels

boiler creates a high turbulence for more efficient combustion of gas.

The customers benefit from operational reliability, high thermal efficiency, fuel flexibility and long equipment lifetime. This has been proven in the large number of installations in operation.

Future developments will address an enlarged field of power generation,

Federal law bulletin (Bundesgesetzblatt BGBl. IS. 1 092).

The law came into effect on 01.04.2002. The admission of KWKequipment to the promotion system of the KWK-law takes place through the Government Office for Economy and Export Control (Bundesamt für Wirtschaft und Ausfuhrkontrolle

The Biograte technology is designed to cope with hard climate conditions and wet fuels.

BAFA). Admission is charged for.

The law protects existing combined heat and power plants and creates special incentives to modernize them rapidly. In addition, the law accelerates and favours the building

with a moisture content of up to 65 %. Furthermore, after-burning time and temperature can be very accurately adjusted. This patented technology allows a variety of bio fuels to be utilised.

The combustion gases from the primary combustion chamber flow into the secondary combustion chamber to ensure the highest possible temperature and thorough mixing in order to completely burn out gas and particles. Hot gases flow from the secondary combustion chamber into the fire tube steam boiler and into a steam superheating device, when superheated steam is needed. The system produces very low emissions of CO2, CxHy, NOx and particulates.

Where a thermal output of more than 12 MWth is needed, a water tube boiler is assembled above the primary combustion chamber. The necessary insulation linings partly cover the water tube walls - depending on fuel properties - in order to maintain the high combustion temperature. In all applications the connecting channel between the combustor and the

and BioGrate technology will be adjusted for still lower emissions and different fuels like RDF, fast growing tropical woods and agricultural biomasses like sugar bagasse and rice husks.

“In the future, the competitiveness of on-site industrial power generation, stricter waste handling requirements and increasing environmental care will drive the growth of renewable energy ”, Mr Heikkinen comments ; “Modular decentralised bio energy systems offer a most interesting international market potential for us.”

CONTACT : Wärtsilä Finland Oy, Biopower Arabianranta 6 00560 Helsinki Finland Tel : +358 10 709 0000 Fax : +358 09 726 2680 biopower@wartsila.com www.wartsila.com

of small KWK-plants up to 2 MW, particularly, the building of small KWK-plants up to 50 kilowatts and fuel cell plants. The operators of subsidised combined heat and power plants can on this presumption get, according to this law, additional payments of 4,448 billion Euros altogether up to 2010. CS * Bundesamt für Wirtschaft und Ausfuhrkontrolle (BAFA)

THE INTERNET LINKS Bundesamt site : www.bafa.de

An on-line application : www.bafa.de/ener/download.htm

Law text : www.bafa.de/ener/vorschri.htm

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COGENERATION LARGE SCALE

Pfaffenhofen has achieved its aim of

climate protection

H u b e r t M a i e r h o f e r, C h r i s t i a n S c h r Ăś t e r, C . A . R . M . E . N

The biomass thermal power station of Pfaffenhofen is one of the biggest biomass incinerators in Bavaria and supplies sustainable heat and electricity for industry, the city and the district.

Germany

he first idea for a biomass heating plant at Pfaffenhofen was put forward in 1989 ; however, there were difficulties to start with.

Then on the 10th of March, 1997 five locally resident businessmen created the "Biomasse Heizkraftwerk Pfaffenhofen GmbH" which eventually completed the project. The combined heat and power station was successfully put into operation in the

T

The biomass power plant of Pfaffenhofen achieved better results than expected on the reduction of CO2 emissions.

A MODERN COMBINED HEAT AND POWER STATION The combined heat and power station Pfaffenhofen produces 26,7 megawatts (MW) of combustion heat in a biomass boiler and 10,5 and 21,0 MW of electrical energy and steam in two reserve boilers.

Over a long-distance heating net the

Emissions of CO2 in Pfaffenhofen in tons per year

180.000 160.000 140.000 120.000 100.000

-32%

80.000 60.000 40.000 20.000 0 1990

1992

1994

1996

Objective of the reduction of CO2 emissions in Germany until 2005: -25% compared to the rate of 1990 (calculation for Pfaffenhofen).

summer of 2001.

The power plant supplies annually 40 000 megawatt hours (MWh) of electric energy into the network of the regional energy supplier. The heat energy is taken by about 150 private, commercial and municipal customers. About 12 kilometres of pipe line were built for it.

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1998

2000 CO2-emissions in Pfaffenhofen.

waste heat is transported to the customers where it is used for the heating and air conditioning of residential and office buildings.

The biomass boiler is a steam boiler with gravity circulation. The water is not circulated by a pump, but it rises by heating during steam gen-

eration. The boiler was designed using self-supporting construction with membrane walls of a very low construction height. The heating surfaces contain only a comparatively low quantity of water making fast starts possible. Thus an even temp e r a t u re i s re a c h e d b y w h i c h unwanted heat stresses which can cause cracks, are avoided.

The boiler is fitted with a watercooled, obliquely placed moving grate This is connected hydraulically to the steam boiler, so that also the grate heat can be used for steam energy generation. Moreover, the grate cooling prevents overheating of the grate bars. The wood chips are drop fed into the burner. By optimising the air supply and periodic grate agitation a complete combustion and low emissions are achieved.

The two reserve boilers of the fire tube type with dual fuel burners are operated with natural gas and guarantee energy supply in case of a failure of the wood boiler and also cover peak demand. Besides, the boilers are used in combination so that the burner heat output does not exceed 50 MW in total. If natural gas should not be available, the reserve boilers can be heated with light fuel oil (HEL). These reserve steam generators are suitable for operation without constant supervision (TRD 604). For safety reasons, the power plant was designed so that no more than two boilers can be operated at the same time.

The hot parts of the plant equipment, for example the boiler walls, water and steam pipes or flue gas channels were insulated and are covered with sheet metal. The exterior of the boiler is insulated with mineral wool, which is fastened in layers with steel attachments and galvanised wire to the walls.

The flue gas condensation equipment makes possible an increase in the energy capture, as the condensation heat of the steam is recovered. Among other things, in this way it is largely possible to remove steam from the chimney plume, something which is often felt by

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neighbouring inhabitants to be unpleasant. In addition, an extremely efficient dust separation is achieved in combination with the application of an electrostatic filter.

The flue gas condensation takes place mainly in winter. Possibly any remaining residual heat in the condensate can be used for heating the boiler buildings or the administration buildings. The combustion air is warmed up with an air pre-heater thus extracting the remaining heat from the waste gas.

A 6,1 MW ELECTRIC POWER The steam produced in the boiler has a temperature of about 450 °C and flows at a pressure of 60 bar into the condensing turbine. The mechanical energy produced by the steam is converted in the high pressure part of the turbine by the generator, which produces a maximum output of 6,1 MW of electrical energy. Part of the steam is taken from the turbine as process steam, another part to the production of hot water.

The generator feeds its output through an electrical transformer into the power plant switchgear. The connection to the high voltage network takes place through delivery switchgear with two feed switches, the plant’s own usage can be supplied by two transformers of 1 600 kVA. A process control system visualises, supervises and optimises operations with automatic controls and makes possible the evaluation of the power plant and its operation.

The biomass combined heat and power plant of Pfaffenhofen represents a saving of 24 million litres of heavy oil, equivalent to 65 000 tons of CO2.

DISTRICT HEATING NETWORK THAT SUPPLIES 150 CLIENTS The hot water net is fed with a constant input temperature of 130 °C. The return flow temperature can,

depending on the load situation, come down to a temperature of 110 °C. The separate customers are supplied through district heating compact stations. The heat distribution is transmitted, in this connection, through

Technical specifications for the biomass boiler Heat input : 26,75 MW Fuel consumption : 10,620 kg / h Boiler performance : 23,3 MW steam output : 62/450 bar /°C steam mass flow : 30 t/h Air mass flow : 12,67 kg / s Combustion wet gas mass flow : 16,15 kg / s Waste gas loss : 2,2 MW Boiler efficiency : 87,2 % Technical specifications of the turbine arrangement Turbine performance : 6,045 kW Generator rated power : 7 560 kVA Generator voltage : 6,4 kV Power factor : 0,8 Turbine rotating speed : 11 300 rpm Generator rotation speed : 1 500 rpm

Investment

The whole investment amounts to 33.313.222 Euros (65.155.000 DM).

Capitalisation amounted to 29.864.558 Euros (58.410.000 DM). This includes an assistance of 14.334.988 Euros (28.036.800 DM) from a grant of 48 % by the free state of Bavaria and the Federal State.

Expenses : plant technology 17.261.213 Euros (33.760.000 DM) Combined heat and power station 3.563.704 Euros (6.970.000 DM) Remote steam and district heating network 5.767.372 Euros (11.280.000 DM) Planning expenses 3.272.268 Euros (6.400.000 DM) Property and fees 1.862.125 Euros (3.642.000 DM) Construction interest rates 1.586.539 Euros (3.103.000 DM) Total sum 33.313.222 Euros (65.155.000 DM)

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be used with the help of the flue gas condensation equipment. It is fed into its own distribution network with an input heat temperature of approximately 75-85 °C and can thus supply the Central heating water and warm water to the customers. In addition, a water condenser removes waste heat from the turbine steam for the production of low temperature heat.

Buildings are supplied with process steam through a remote steam network. An electric fast steam generator serves as spare capacity and as a peak load boiler.

3

750 M OF WOOD CHIPS BURNT EVERY DAY For firing the boiler exclusively untreated wood is used in the form of forest processed chips and sawmill waste wood. Half of the plant’s needs are covered from regional agriculture and forestry, the other half from wood manufacturing and wood processing enterprises. The plant has been designed for forest fresh wood chips and sawmill waste wood with a moisture content up to 45 per cent.

On the site of the heat and power station a reception hall was built for the delivery and storage of the fuel.

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About 10.500 cubic meters of fuel can be stored in it, an amount which is sufficient for approximately four to five days of operation. Delivery takes place with tipping containers, which have a capacity of about 38,5 cubic meters. The material is placed on one of two walking floors, which are installed running through the whole fuel storage. Into this channel the fuel is unloaded directly. As soon as the capacity of the walking floor is reached, the wood chips are transported into the storage room. Then outside normal delivery times the walking floors are supplied by a crane arrangement from the warehouse.

Approximately 750 bulk cubic meters fuel are needed daily.

Augers, installed below the delivery end of the walking floors, take care of the even movement of the right amount of fuel to the chain-scraper conveyors. After that, the fuel is transported to the holding silo of the biomass burner.

To prevent burn back in case of fire, between the fuel warehouse and boiler house in the area of the chainscraper conveyors, there is a wedge slide gate valve, which prevents not propagation of flames or smoke. In addition, the heat and power station is equipped with a smoke detector centre, to which the circuits of the fire alarm detectors from the whole power plant are connected, and the centre indicates to the personnel where fire or smoke has appeared.

Forwarding of alarms from this centre is also possible to the local fire brigade or police.

The fire box of the biomass boiler is sized generously to guarantee complete combustion. Also the heat exchange surfaces of the combustion chamber are large enough to

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CARMEN

Since its opening in 2001, the biomass power plant of Pfaffenhofen has brought about a important decrease of the pollution in the city.

remote monitoring in the control room. From the control room, the separate heat delivery stations of the buyers are controlled which guarantees an optimised operation of the district heating net and the customer's plant. The care of buildings with air conditioning takes place through an absorption cooler which is connected in the hot water supply.

Also medium temperature heat can

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The boiler burns non commercial wood as wood chips and saw mill waste.

guarantee that the flue gas temperature is low enough before the superheater that adhesion of the fly ash is avoided.

The waste products are ashes : coarse, medium and fine ash as well as cinder. The unburnable fraction from the burner are delivered through a wet-collection system under the burner into a container. Before the economiser a coarse cyclone was installed to reduce the dust loading on the economiser substantially. In addition the flue gas of the biomass burner are de-dusted by means of a high-efficiency filter arrangement.

The coarse ash and medium ash can be used in agriculture and forestry as a fertilizer, because they contain, apart from nitrogen, all the main and trace element nutrients necessary for plant growth. The rest of the ash (fine ash) gets removed in the filters. It is not usable and is disposed of appropriately.

The storage hall can receive 10 500 m3 of wood chips.

Everyday, 750 m3 are burnt.

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The operator of the power plant is the company Biomasse Heizkraftwerk Pfaffenhofen GmbH, which was created in 1997 by five businessmen from Pfaffenhofen.

The main customer of the heat and power station is the Hipp company in addition some other industrial and workshops, municipal plants like Ilmtalklinik, the town hall, the District Office and different schools in Pfaffenhofen and more than 100 private heat energy customers who are supplied with district heating. The cooling output is applied to the air conditioning of office buildings and as process cooling for the Müllerbräu brewer y. Moreover, the normal emi s s io n v alue s i n B i om a sse Heizkraftwerk Pfaffenhofen are clearly reduced by the high-efficiency flue gas cleaning systems.

be produced to be more than 90 per cent CO2-neutral. An enormous contribution to the protection of the climate is thereby performed. Approximately 24 million litres of heating oil can be saved annually by the company of the combined heat and power station Pfaffenhofen thus avoiding 65 000 metric tons of carbon dioxide (See figure 1).

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OPERATOR AND CUSTOMER

FOR MORE INFORMATION : Biomasse Heizkraftwerk Pfaffenhofen GmbH Raiffeisenstr. 19 85276 Pfaffenhofen Germany Contact person : Mr Bauer Tel. : +49 8441 498 490 Fax : +49 8441 498 499

Thanks to a turbine of more than 6 MW, 40 000 MWh of green electricity are supplied to the network each year.

THE CONTRIBUTION TO THE ENVIRONMENTAL PROTECTION If fossil sources of energy are replaced with biomass, electricity and heat can

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