As the coal-fired power station at Västhamnsverket in Helsingborg was one of Sweden’s largest, conversion to biofuel became a priority following the introduction of a carbon tax in Sweden.
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 200 MW boiler so that it could burn up to 50% biomass alongside coal – in this case, wood pellets.
WSP had to ensure that the fuel-handling system functioned well and could cope with the new fuel, as well as make some modifications to the mills so that the wood pellets would not ignite before reaching the boiler.
The solution was to recirculate the flue gases to reduce 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 WSP was much in demand to relay their findings to the wider industry. The team 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.
The heat balance of the plant was changed so the backpass had to be completely modelled and retrofitted to cool the flue gas correctly. The ‘sooting’ system for cleaning dirt and dust from the surface of the equipment needed to respond to the new fuel as well.
Our team monitored the plant constantly to work out how the output could be maintained. At the end of the project, we had maintained the efficiency of the plant, a great achievement given the difficulties associated with the conversion.
We not only designed the project, but also worked with the client to procure the equipment and monitored the boiler’s performance for two years, developing a computer program which now allows other clients to benefit from the same analysis.