Fig. 2 Relationship between viscosity and temperature of fuel oil
On the other hand, it is possible to grasp the combustibility specific to the fuel by using the device on the laboratory scale to analyze various combustion characteristics and thermal behaviors in an extremely simplified system. Also, the device on the laboratory scale can rapidly and easily achieve the evaluation with a small amount of fuel oil, and is effective for the trouble shooting. Several evaluation methods are introduced below.
(1) (TG-DTA: Thermogravimetry - Differential Thermal Analysis)
The measuring instrument is TAS-300 of Rigaku. This instrument is capable of grasping the change in weight and the thermal behaviors including the exothermic and endothermic changes from the room temperature to approximately 1400℃ in air at normal pressure. Fig. 3 shows the TG-DTA chart of marine fuel oil.
The temperature rose from the room temperature to 1000℃ in the air flow. The temperature rise speed was 100℃/minute.
The peak rise point in the vicinity of 300℃ of the DTA curve is defined as the ignition temperature, and the temperature at which the whole sample is burnt out is defined as the burnt out temperature. These are useful for the target of the combustibility. Various characteristic of the fuel can be read qualitatively from the whole TG-DTA chart.
Fig. 3 TG-DTA evaluation of marine fuel oil
(2) Droplet combustion analyzer
This analyzer is of the construction that a sample oil droplet of approximately 1.0 mm in diameter is suspended from a tip of a quartz thread of 0.2 mm in diameter, and burned in a portable electric furnace. The condition of combustion is recorded by a CCD camera, and analyzed using the reproduced image. This analyzer was manufactured with the device developed by the Ship Research Institute as a model1). Fig. 5 shows an example of the evaluation photos of the droplet combustion analysis. The fourth one shows the condition after the completion of the combustion of volatile portion and immediately before the combustion of carbon.
Fig. 4 Droplet combustion analyzer
