VÄSTHAMNSVERKET POWER STATION, HELSINGBORG


SWEDEN WSP SWEDEN PIONEERED THE CONVERSION OF A COAL-FIRED POWER PLANT TO BIOFUEL, IN A VERY CHALLENGING PROJECT THAT HAS BECOME AN EXEMPLAR FOR THEWORLD.


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Conversion of a coal-fired plant had never been attempted on this scale before. There was nothing that we could copy from anywhere else – we had to invent the solutions ourselves. It should be a model for the rest of Europe.


Ola Thorson, Department Manager, WSP Sweden


QUICKFACTS


CLIENT Öresundskraft PROJECT TEAM WSP office: Sweden SERVICES PROVIDED Process Engineering


PROJECT SUMMARY Process design, Boiler Heat Balance, Technical Specifications, Procurement, Operational Follow-Up


KEY CHALLENGES First large Scale Conversion of coal-fired plant to 100% Biofuel, with maintained maximum thermal output of 200 MW


100% BIOFUEL


Conversion from 100% Coal to 100% Biopellets


Image courtesy of Öresundskraft


The coal-fired power station at Västhamnsverket in Helsingborg was one of Sweden’s largest, so when a carbon tax was introduced it became a priority for conversion to biofuel. Helsingborg’s energy company Öresundskraft commissioned WSP to carry out the pioneering conversion in two phases, stretching over several years.


The first phase involved adapting the 200MW boiler so that it could burn up to 50% biomass alongside coal – in this case, wood pellets. “Wood pellets are not so rich in energy as coal, so you have to feed in a larger volume,” explains Ola Thorson, Department Manager at WSP Sweden. “We had to ensure the fuel-handling system was functioning well


and could cope with the new fuel, and make some modifications to the mills, where the coal is milled before it is fired, so that the wood pellets did not ignite there before they reached the boiler.” The solution was to recirculate the flue gases to reducing oxygen content in the mills, and install a vacuum cleaning system to remove dust from the wood pellets and explosion doors above the storage space.


A conversion project on this scale had never been attempted before, so Thorson’s team were much in demand to relay their findings to the wider industry – they presented papers on the project at several international conferences on clean energy.


The second phase, running from 2000 to 2006, involved the full conversion of the plant to accept 100% biomass – an even taller order. “We reached the limits of the existing boiler, and we couldn’t fire more than 50% biomass without major modifications.” For example, the heat balance of the plant was changed so the backpass had to be completely modelled and retrofitted to cool the flue gas correctly and the ‘sooting’ system for cleaning dirt and dust from the surface of the equipment had to respond to the new fuel too. “We had to monitor it constantly to work out how to maintain the output. We wanted to see any problems in real-time, so we could make the necessary adjustments,”


says Thorson. At the end of the project, WSP had in fact maintained the efficiency of the plant, a great achievement given the difficulties associated with the conversion.


WSP not only designed the project, but worked with the client to procure the equipment and monitored the boiler’s performance for two years, developing a computer programme which will now enable it to conduct the same analysis for other clients. “We think this project could be repeated in many places,” says Thorson. “It is a big opportunity for countries all over the world that have to do something about their coal-fired power stations.”


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INDUSTRY


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