Unsteady simulation of air pre-heater
The air pre-heater on the biomass boiler at Smurfit Kappa Krafliner in Piteå vibrates when run close to its maximum capability. This generates such high sound levels that the working conditions are compromised. The contracted supplier Metso Power has made effort to solve the problem but the noise st...
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| Format: | Bachelor Thesis |
| Language: | English |
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2010
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| Online Access: | http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-57380 |
| Summary: | The air pre-heater on the biomass boiler at Smurfit Kappa Krafliner in Piteå vibrates when run close to its maximum capability. This generates such high sound levels that the working conditions are compromised. The contracted supplier Metso Power has made effort to solve the problem but the noise still remains. Jan-Olov Aidanpää and Jan Granström at the Division of Solid Mechanics at Luleå University of Technology have made measurements of the vibration and calculated some of the natural frequencies of the structure. They also suggested a numerical investigation of the flow to find possible excitation frequencies. This thesis by literature review summarizes the potential mechanisms in a flow that could cause the vibration. The most likely mechanism is found to be acoustic resonance coupled to vortex shedding as the flue gas pass over the inline tube array situated in the pre-heater. Numerical simulations are made with the code ANSYS CFX on this hypothesis. Possible excitation frequencies are found in the flow and the hypothesis is found likely. But all other possibilities cannot be ruled out due to the complexity of the problem. Validerat; 20101217 (root) |
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