The
objective of this study was to evaluate the flow of a film
of bio-oil in a cylindrical tube similar to the tube of a heat exchanger
found in a fast pyrolysis unit of sisal residue in a fluidized bed.
The velocity profile of bio-oil was determined from the momentum balance
and the equation that describes the rheological behavior of the fluid.
The rheological behavior of bio-oil was determined at 60, 70, 80,
90, and 110 °C, and eight models to describe the rheological
behavior were evaluated. The Sisko, Herschel–Bulkley, Mizrahi−Berk
and Robertson−Stiff models all performed similarly, and they
adequately represented the rheological behavior of bio-oil with a
pour point of 55 °C derived from sisal residue. The variation
of the thickness of the bio-oil film on the walls of a cylindrical
tube and the velocity profile in the film as a function of temperature
were determined empirically using the four best rheological models.
Only the equation of flow employing the rheological model of Sisko
showed results consistent with the behavior of the fluid.
The objective of this research was to study the fast pyrolysis of sisal residue, performed in a pilot unit with a fluidized bed reactor. The tests were carried out by varying the flows of nitrogen (8−14 N m 3 /h), biomass (10.33−25.95 g/ min), and temperature (450−550°C). The experimental planning technique was used to identify the number of tests and the influence of operational variables on the bio-oil yield. One of the highest H 2 /CO (2.16) ratios was found from the eighth test on, which was an appropriate value for the production of methanol and liquid biofuels. All bio-oil samples produced were characterized, and the results showed that the sisal residue bio-oil is different from other bio-oils reported in the literature. It has high viscosity at room temperature, with a pour point of 55°C and average molecular weight of 414.2 g/mol. In addition, phenolic species completely prevail in relation to the other monomeric components. The biochar obtained is an amorphous, fine powder. Despite the porosity, its specific surface area is lower than of commercial activated carbon.
The viscosity of sisal residue bio-oil was evaluated using the variation of the operational conditions of the fast pyrolysis process in a fluidized bed. The bio-oil was produced in a pilot plant from tests that were designed using the technique of experimental design. In this work, the effect of the flow rate of the inert gas (N 2 ), the biomass mass flow rate, and the reaction temperature on the viscosity at the shear rates of 40 and 75 s −1 was investigated. The lowest viscosity was obtained when the N 2 flow rate and the temperature were at their lowest values (8 N m 3 /h and 450 °C) and the biomass flow was at its highest value (1560 g/h). The low-viscosity bio-oil was used to investigate the influence of the shear rates at its most critical flow condition (2−26 s −1 ) at temperatures of 60−110 °C. It was found that at 60 °C, the bio-oil viscosity ranged from 2699 to 353 mPa•s when the shear rate increased from 2 s −1 to 26 s −1 . The lower value of this viscosity (353 mPa•s) is equivalent to the higher value reported in the literature. An empirical model of viscosity versus temperature was determined and compared with existing models. This evaluation was performed at three shear rates (2 s −1 , 14 s −1 , and 26 s −1 ) and at temperatures ranging from 60 to 110 °C. The model proposed in this study showed deviations much smaller than those obtained with the application of the most used models.
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