Refuse to fuel cement furnace
Jan Erik Kaarø
This autumn Norcem will start to fuel its cement furnace in Kjøpsvik with briquettes of ordinary household refuse. What is known as FAB (Norwegian acronym for "processed alternative fuel") was developed by NTH scientists as long as 15 years ago.
Associate professor Erling Østerbø at NTF fires up one of NTH's fluidized bed furnaces with ground household refuse.
If everything goes according to plan, the new main airport at Gardermoen might be heated using the same fuel. Military bases in Northern Norway and a number of local authorities are also considering building such heating plants
FAB plant ready for use in 1985
However, if the FAB principle is now making a breakthrough to some extent, Erling Østerbø (58), an NTH associate professor state that the road from idea to practical application has been more than long enough. Østerbø led NTH's fuel briquette development project towards the end of the 70s and has followed it ever since. The first and so far only FAB installation in Norway was completed as early as 1985. Søndre Vestfold Waste Company´s facility at Grinda waste dump near Larvik converts refuse from seven local authorities to energy briquettes. These are sent to Norske Skog´s Sande Paper Mill where they are used to fuel a fluidized bed boiler. This is another technology that has been the subject of a great deal of research at NTH´s Dept. of thermal energy and SINTEF Applied Thermodynamics, but which has yet to make a breakthrough in Norway.Waste refinery
An FAB plant is simply a waste refinery. Refuse is ground up and dried. The resulting mass undergoes several rounds of separation before the briquettes are finally compressed under high pressure. The advantages of the briquettes are that they can be stored, they have a high energy density and producing them is easy to combine with recycling of glass, plastics and heavy metals. The briquettes can also be produced from other materials such as wood-chips or bark. A plan has been launched to heat the new Gardermoen Airport by means of a plant fuelled by multi-fuel of this sort. During the past few years, a number of plants that produce refuse-derived fuel (RDF) have been built in other countries.Hålogaland Resources in Narvik, which receives refuse from 11 local authorities in the Counties of Nordland and Troms, is currently installing an FAB plant. Briquettes will be sent to Kjøpsvik, 100 km south of Narvik, where they will meet some 10% of the cement factory's fuel requirements. Frank Nielsen, technical manager at Norcem, does not expect any practical problems to arise from using waste as fuel. Norcem´s management have visited several cement factories in Belgium, Switzerland and Germany that have long been firing their furnaces with various types of refuse.
Environmentally friendly combustion
Norwegian researchers were early participants in the process of developing fluidized-bed (FB) furnaces, which have been widely adopted throughout the world during the past 20 years. A fluidized bed consists of a mixture of hot sand, ash and a small percentage of fuel. The "bed" is kept in constant movement by means of air which is blown into it from below."The FB technique controls emissions to the environment in a unique way. Few nitrous gases are created, and by adding chalk during combustion, releases of sulphur dioxide can be reduced quite simply by a good 90%. Another advantage is that absolutely anything that will burn can be used in the furnace, which is just as suitable for refuse briquettes as it is for waste oil and tarry products," claims Erling Østerbø.
At present there are only four commercial fluidized bed plants in Norway. The first Norwegian FB furnace was built by the Jotun Group in Sandefjord in 1975 and has been used, among other purposes, to burn hazardous waste such as PCBs from the company's paint manufacturing process. Norsk Hydro is another company that is considering adopting this technology at one of its aluminium smelters. Four experimental furnaces of various sizes have been installed at NTH/SINTEF. Samples of different types of fuel from all over the world come here for testing.
Much of NTH/SINTEF's research on FB and FAB has been done as part of the four-year "Energy from Waste" project which is due to finish this year. The project is supported by the Research Council of Norway and 24 local authorities.