Projeto e estudos preliminares de modelagem de um reator oscilatório para produção de biodiesel

Abstract

In the last 20 years the oscillatory technology has been studied mainly in some English universities. The researchers of the area had looked for to improve the knowledge on the not usual mixture of the OFRs reactors (Oscillatory Flow Reactor). The OFRs reactors are considered processes intensifiers, which means they are capable to process of continuous form reactions that occur in batch and need long times of residence. The reactions for attainment of biodiesel are considered long and therefore in the majority of the industries, the fuel is produced in batch reactors. Due to the great volume of production a continuous process would be more advantageous. The projected reactor to be used of continuous form in the production of biodiesel is totally based on the oscillatory technology. For the analysis of design of the reactor eight parameters of system OFR had been observed, including 3 geometric ones (D, do and L), three parameters of operation (u, ω, x0) and two fluid parameters (ρ and υ). The analysis of the measures chosen for the reactor was made in relation to the involved dimensionless groups as Reynolds (Ren), oscillatory Reynolds (Reo), the reason between the superficial average velocity and oscillatory velocity (ψ) and number of Strouhal (St), for the operational conditions of amplitude from 5 to 10 millimeters and frequency from 2 to 5Hz. The parameters were analized observing the reactions conditions of biodiesel production. It had been observed also the fall of pressure in the reactor and the density of wasted energy, the analysis was made of comparative form using reactors with other diameters of tubing , and the chosen project had the geometric parameters of D=25,4mm , do =12,2mm. For the value of the distance between the adjacents baffles of the OFR reactor was chosen the range from L=1,5D to 2D. The allowed maximum operational capacity for the oscillatory mechanism was given for the frequency of 13Hz and amplitude of 15mm. For these conditions of maximum amplitude and frequency had been made kinematics and dynamic analyzes for determination of the adequate spring to the oscillatory mechanism, the standardized spring of stamp was the type of spring chosen for the project, the value of the elastic constant of the spring was of 5,4N/mm. For the modeling was considered a model of two interconnected CSTRs representing a CSTR that was placed in series with others of same configuration, what it generated a model of 3 parameters (N, θ, φ) to represent the oscillatory reactor. Language FORTRAN and a subroutine of numerical integration based on Runge- Kutta method present in library IMSL was used to get the DTR curves and the surface of reply for the yield of the transesterification reaction in relation to the parameters θ and φ. The yield range below yield of the batch reactor has indicated that the Model can be used to represent a non-ideal oscillatory reactor, but it is necessary to evaluate the Model experimentally. The conditions were obtained with a fixed N value (number of CSTRs) and the variation of the parameters θ and φ.