Throughout the times, fossil fuel consumption has suffered a considerable increase. Its search began with industrialization and the need to increase activities due to the energy demand and grew with the expansion of the transport network. Fuel oil and Diesel had since very soon found applicability on internal combustion engines, cars, marine diesel engines, plains and diesel-electric power units.
With the unstoppable growth of fuel prices and with the latest restrictive regulatory legislation fossil fuel emissions taking place (to mitigate air pollutant consequences to the atmosphere as well as raising awareness among the public) it becomes more urgent than ever to know the fuel that you are burning.
Getting to know the exact characteristics and technical parameters of your product will not only guarantee companies to save money but can also provide the possibility to take proper actions in advance. Some of the fuel and diesel more relevant parameters are related to their physical/structural, thermal and chemical properties.
In terms of the physical parameters that should be taken into consideration we can highlight: the fuel apparent density and its viscosity (kinematic, dynamic, bulk). The first properties relate to the amount of matter present per unit of volume. It can be easily determined in a quick and non-destructive way by means of a viscometer (digital or not). In other hands, the viscosity characterizes the resistance of a given fluid to flow, as well as the shear deformation.
It corresponds to the internal friction in fluids due to intermolecular interactions and this magnitude is generally a function of temperature. In addition to being a function of temperature, in particular, the kinematic viscosity is a function of the specific mass of the product.
Relatively to the fuel’s chemical properties, the major relevant parameters are: the determination of ash content, determination of water content and its nature, the determination of sulphur content, the determination of total sediments, the determination of asphaltenes, presence of metals, and the fuels total acid value and base value (TAN and TBN).
The ash content consists of the inorganic residue remaining after combustion of a fuel sample /oil in the presence of air at a specific high temperature. It is a measure of the amount of non-combustible inorganic material (Va, Na, Ca, Mg, Zn, Pb, Fe, Ni). They may occur naturally or result from refining, or contamination during storage or distribution stages. In the same way, the total sediments correspond to the insoluble organic material and inorganic material present in the fuel sample.
Asphaltenes correspond to heavy petroleum aromatic compounds with higher boiling points. They are formed by aromatic rings, having paraffin-like chains and high polarity. Asphaltenes can result in serious problems during the production phase (i.e.: the formation of organic deposits in reservoirs and runoff lines, changes in rock wettability and the formation and stabilization of emulsions). Some metals present in the fuel such as the ones mentioned above can be hazardous to the equipment in contact with fuel, causing problems such as corrosion, damaging materials due to oxidation-reduction reactions.
The water amount and water nature is also another important parameter to take in consideration when using fuel oil or diesel samples. The water amount in the fuel can be associated to the possibility of corrosion problems, especially in cases where sulfur is high, but can also affect the calorific value of the fuel, causing the nebulization of the product (due to the formation of emulsion). Not only the amount of water present is important but also its nature, since the presence of salts in water lead to phenomena like corrosion or degradation of materials.
As indicated before, due to the necessity of controlling fuel emissions after burning, it is also important to control the initial sulfur amount that the fuel possesses, since it is related to the Sulphur oxides emitted to the atmosphere. There could be qualitative or quantitative methods to determine the presence of Sulphur. Some of the most know techniques are the determination of Sulphur by Doctor Solution or the determination by x-ray diffraction techniques (determining its value from ppm to wt%).
As important as the physical and chemical parameters are the thermal parameters: Flash Point, Fire Point, Pour Point, determination of High Heating Value (HHV) and Low Heating Value (LHV), determination of the Carbon Aromaticity Index (CCAI).
The Flash Point corresponds to the lowest temperature at which a fuel or oil releases enough vapor to form a flammable mixture from an external source of heat. It is not sufficient for combustion to be maintained. The Fire Point of combustion is the lowest temperature at which the vapor of a sample will continue to burn for at least 5 seconds after ignition by an open flame. The Pour Point of the sample corresponds to the minimum temperature at which the movement in the sample under analysis is verified on the applied test conditions. These 3 thermal properties are extremely important since they can give the user the information about the application range (combustion), and also handle and storing data (safety limits).
By knowing the CCAI value it enables to avoid the use of fuels with non-characteristic values of viscosity and density, providing also information about the ignition delay of the fuel. Also knowing the HHV and LHV of the fuel, the user can estimate the energy released per unit mass in the oxidation of the fuel and analyze its applicability.
TecnoVeritas is a 23 years old company dedicated to industry, specialized in engineering services and solutions to the shore and maritime industries. Among our services, we have a well-equipped Fuel Laboratory and experiment professionals that can provide companies a helping hand in characterizing their fuel samples. We can guarantee a quick analysis and emitted detailed reports with a suggestion on how to overcome difficulties. To know more get in touch with us or visit the laboratory analysis page.