Abstract
Circulating Fluidized Bed (CFB) boilers are widely used for multi-fuel
combustion of waste and bio-fuels. When several non-homogeneous fuels, having varying heat values, are
burned simultaneously, the boiler control system can be affected by various control
challenges, especially since it is not feasible to reliably measure the energy content of the
multi-fuel flow. In order to fulfill energy production needs and maintain the ability to burn low grade
fuels, co-firing with high heat value fuels such as gas, oil or coal is needed.
Fuzzy Logic Control (FLC) has been successfully used for solving control
challenges, where operators' process expertise can be transformed into automation. Real life
control objects are often non-linear because the dynamics change with the operating point, or there might
be other essential non-linearities in the combustion process.
The proposed fuzzy control applications were developed to solve control
challenges the operators meet in daily operation of a 150 MW(th) CFB at Varenso Oy's (Stora
Enso Oyj) K6 boiler in Varkaus Finland. Before implementing the applications in the fullscale
boiler, they were tested at a 2 MW(e) pilot plant boiler at Foster Wheeler Energia Oy's Research
Center in Karhula, Finland.
According to the industrial experiments, the four applications (steam pressure
control, compensation of fuel quality fluctuation, fuel-feed optimization and increased
bed inventory monitoring) discussed in this thesis, showed satisfactory performance and
various improvements to the boiler control were achieved. Fuzzy logic control was shown to be a notable
tool to improve the multi-fuel CFB boiler control.
| Identifer | oai:union.ndltd.org:oulo.fi/oai:oulu.fi:isbn951-42-5519-4 |
| Date | 10 January 2000 |
| Creators | Karppanen, E. (Erkki) |
| Publisher | University of Oulu |
| Source Sets | University of Oulu |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/doctoralThesis, info:eu-repo/semantics/publishedVersion |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess, © University of Oulu, 2000 |
| Relation | info:eu-repo/semantics/altIdentifier/pissn/0355-3213, info:eu-repo/semantics/altIdentifier/eissn/1796-2226 |
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