| Title | Integrity Study of Cooling Tower Wooden Structure |
|---|---|
| Authors | W. Wirawan, E. Tri Bahtiar, Khuschandra |
| Year | 2016 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | wooden structure, degradation, allowable stress, stiffness, resonance |
| Abstract | In order to assess the integrity of the wooden structure of Cooling Tower (CT) Unit 1 after 15 years of operation, Star Energy Geothermal Wayang Windu Ltd. conducted physical, chemical and mechanical testing of the wood. The testing was applied to the used wood as well as spare wood. Chemical tests revealed that surface degradation had reached up to 2.5mm depth. Mechanical tests concluded that allowable stress for compression parallel to the grain was slightly lower than NDS 2005 specification and Modulus of Elasticity (MOE) was significantly lower. When the value of MOE is significantly lower, the stiffness of the structure decreases and can cause a higher level of vibration. Due to this situation, dynamic analysis of the machine and structure has been conducted. It has revealed the phenomenon of resonance and flow induced vibration. Resonance vibration has been successfully reduced, but flow induced vibration sometimes still occurs. Based on this assessment, it can be concluded that the CT can still be reliably operated, but deformation and vibration will occur at higher levels. Further study to assess the fatigue life of the wooden structure has been planned to provide permanent mitigation. |