ABSTRACT
The newer 2020 fuels known as the Very Low Sulfur Fuels (VLSFOs) have higher paraffin content when compared with heavy fuel oil (HFO). Although paraffinic blends have excellent ignition and combustion properties, they also have more wax deposition issues and poor cold flow properties.
Wax crystals that are formed at temperatures below the Wax Appearance Temperature (WAT) for the VLSFO and can lead to filter blockage and potential engine shut down. Wax precipitation becomes more challenging in winter, once the temperature drops.
Therefore, it is important to have enough heating capacity in tanks and pipes to prevent wax formation. There are no parameters for identifying cloud point for residual fuels in the ISO 8217 2017 table two. Determining Wax Appearance Temperature (WAT) by Differential Scanning Calorimetry (DSC) method is one of the techniques to estimate the temperature at which wax deposition occurs for dark fuels.
While numerous reports show a 3 to 15 ° C difference between WAT and Pour Point, the actual difference we observed between WAT and Pour Point is 3 to 44°C. As a result, the usual recommendation of storing the fuel at 10°C above the Pour Point will be inadequate in preventing the formation of wax crystals in the fuel. In our opinion, it is important to measure the WAT to ensure the proper storage and handling temperature– hot enough to prevent the wax crystallization and not too hot to exacerbate stability issues. The focus of this paper is on understanding the correlation between the Wax Appearance Temperature and Pour Point of VLSFOs and also determining the relationship between the WAT and WDT (Wax Disappearance Temperature).
In addition, the relationship between the chemical composition of the fuel, SARA analysis (Saturate, Aromatic, Resin, and asphaltene), and cold flow properties such as pour point and WAT is discussed in detail in this study.