Resumo:
Heavy fuel oils (HFO) are widely exploited to produce electric energy in Thermoelectric
Power Plants (TPP), mainly due to the amount of heat released during its combustion.
Economic factors also influence the use of HFO for energy generation, including the low
cost of energy content, availability due to raw materials, ease of transport and storage,
low operating investment costs, among others. The power to produce energy from HFO is
defined by its calorific value (or heating value) and is linked to the quality of the fuel oil and
the presence of contaminants, such as water. A fuel oil with properties different from those
expected/specified can not only decrease the calorific value, but also can cause damage to
the TPP equipment. Therefore, the analysis of the quality of fuel oils is of great importance
for TPPs. This work proposes a methodology to estimate three parameters of the quality
of fuel oils: the density, the water content in the oil and the calorific value. The proposed
methodology has developed a system that has techniques such as ultrasonic, capacitive and
temperature measurement to estimate quality parameters. The ultrasonic system is based
on the propagation time of the ultrasonic waves to estimate two quantities, the speed of
sound and the flow of the fluid. The capacitive system correlates the capacitance variation
with the water content in oil, starting from the existing association between sensor, fuel
oil and water. Temperature measurement data is used in conjunction with sound velocity
data to compensate for the effect of temperature on the density estimation. Based on the
temperature and velocity of sound information, and using a classification algorithm, a
method was developed to recognize the existing similarity between the OC under analysis
and the OC information from a database. With the result of the classification, the scores
and the information from the database are obtained to estimate the density. Finally, the
calorific value is calculated by associating the density and water content data. The results
obtained from the tests were compared with data from laboratories and technical sheets
of the OCs, reaching relative deviations lower than 1.0% and 0.5% for the density and
calorific value, respectively.
