Pyrolysis Properties and Kinetics of Typical Liquid Oils in Wind Turbine Nacelle

To evaluate fire risk of typical liquid oils applied in nacelle of wind turbine, pyrolysis properties prior to combustion should be known. Pyrolysis properties of three kinds of typical oils of hydraulic oil, gearbox oil and transformer oil were studied by using Thermogravimetry (TG)- Differential Scanning Calorimetry (DSC) technique. Pyrolysis kinetics was analyzed. Apparent activation energy and pre-exponential factor were calculated by using Kissinger method. Results show that according to the TG-DSC analysis, for all three oils, the pyrolysis processes can be divided into three stages. The first stage is evaporation from room temperature to 140.1 °C (gearbox oil), 123.4 °C (transformer oil), and 144.1 °C (hydraulic oil). The second stage is the primary mass loss stage, corresponding temperature is in the range of 140.1–542.0 °C (gearbox oil), 123.4–294.1 °C (transformer oil), and 144.1–329.5 °C (hydraulic oil), among which the temperature of maximum heat mass loss rate of gearbox oil, transformer oil and hydraulic oil is 402.6, 220.1 and 262.6 °C. The third stage is the end of char oxidation and mass of residual char is kept constant, the temperature is higher than 542.0, 294.1, and 329.5 °C. Activation energies and pre-exponential factors were obtained by kinetic analysis, according to the pyrolysis kinetics analysis, the hydraulic oil is more prone to be pyrolyzed than gearbox oil and transformer oil and this provides a basis for judging the combustion characteristics of oil products by pyrolysis kinetic parameters in the future.