Tese
Desemulsificação de petróleos assistida por ultrassom e posterior caracterização das fases água e óleo
Fecha
2011-08-19Registro en:
ANTES, Fabiane Goldschmidt. Desemulsificação de petróleos assistida por ultrassom e posterior caracterização das fases água e óleo. 2011. 47 f. Tese (Doutorado em Química) - Universidade Federal de Santa Maria, Santa Maria, 2011.
Autor
Antes, Fabiane Goldschmidt
Institución
Resumen
The effect of ultrasound (US) for demulsification of crude oils with different
characteristics (viscosity, density e water content) was investigated, without using
chemical demulsifier. Initially, the treatment using US was evaluated, using direct or
indirect (using water as US propagation medium) application with probes. Water
separation from emulsions was only verified when US was indirectly applied.
Therefore, indirect US treatment was studied, using different systems. Experiments
were carried out using ultrasonic baths with power of 100 or 200 W (frequency of 25
and 45 or 35 and 130 kHz) and cup horn systems with power of 130 and 750 W
(frequency of 20 kHz). The best conditions of amplitude, time and temperature of US
treatment were optimized. Synthetic crude oil emulsions of two crude oils were
prepared with water content of 12, 35 and 50% and median drop size distribution of 5,
25 and 50 μm. Moreover, natural crude oil emulsions with water content of 12.1 ± 0.1
and 33.5 ± 0.5% (API gravity of 11.1 and 10.8, respectively) were evaluated. For
synthetic crude oil emulsions, using cup horn systems, demulsification efficiencies
between 40 and 50% were obtained, using 60 and 20% of amplitude for the 130 and
750 W systems, respectively. Using ultrasonic baths (frequencies of 25, 35 and 45
kHz), efficiencies between 50 and 60% were obtained, with 100% amplitude. At 130
kHz, no water separation from crude oil emulsions was observed. For natural crude
oil emulsions, efficiencies better than 70% were obtained using cup horn systems or
ultrasonic baths (for crude oil with initial water content of 12.1 ± 0.1%). Water and oil
phases separated from crude oil emulsions using US were also characterized. It was
observed that acidity, metals and sulfur content did no change after treatment with
US. Additionally, the separated water was analysed using ion chromatography and
gas chromatography coupled to mass spectrometry (after derivatization) to evaluate a
possible migration of acid species to the water phase during US treatment.