Study On Production Of Biodieselcontinuously By High Intensity Pulsed Electric Fields

Along with the great demand for energy, the biodiesel has been paid more attention. However, the applied techniques have the following drawbacks: The reaction time is long, and the producing is intermission. In this paper, the technique of producing biodiesel continuously is studied which using high intensity pulsed electric fields(PEF), this technique can promote the reaction, reduce the time and continue the process.This paper took the soybean oil as study object and experimented with PEF, the esterify mechanism was discussed, and the following conclusions were drawn:First, the technology and parameters were studied in this paper on condition that we used a constant temperature oscillator to produce biodiesel.(1)The following conclusions through the single factor analysis were drawn:â‘ The catalyst proportion influenced the biodiesel productivity. With the density of NaOH increased, the productivity rose, but when density surpassed 1.1%, the productivity decreased. We must keep the density between 0.95%¹.05% in order to obtain higher productivity.â‘¡The proportion between methyl alcohol and oil influenced the biodiesel productivity. With the density of methyl alcohol increased, the productivity grew rapidly and achieved the maximum when the proportion between methyl alcohol and oil reached 6:1. But with the density of methyl alcohol climbed continually, the productivity remained stable. We chose the mole proportion 6:1 in the end.â‘¢The reaction time influenced the biodiesel productivity. In the initial stage, with the time lasted, the productivity increased obviously, but when time surpassed 1 hour, the productivity reduced slightly and then tended to be stable. Therefore, the reaction time should be controlled in 1 hour.â‘£The temperature influenced the biodiesel productivity. Between 50⁷0℃, the productivity increased along with the temperature, and then declined slightly after the temperature surpassed 70℃. In the actual operation, we should select 60℃as the suitable temperature.⑤The mixture intensity influenced the biodiesel productivity. With the mixture strengthened, the reaction rate obviously sped up. We should strengthen the mixture intensity to promote the reaction as far as possible.(2) The following conclusions were drawn through the orthogonal test analysis.The mixture intensity was the most important influence factor among five factors, next was the catalyst density, and then were methyl alcohol density, the time and the temperature .We should choose the most suitable combination of A3B3C3D2E4, and that was to say the catalyst 1.0%, the methyl alcohol/soybean oil was 6:1, reaction time was 60min, temperature was 60℃, mixture level was the highest.Second, the technology and parameters were studied in this paper on condition that we used PEF to produce biodiesel.(1) Several common assisted solvent were compared, and tertiary butyl alcohol was selected which account for 10% soybean oil quality.(2) The colloid mill with propeller mixer and a constant temperature oscillator were compared, and colloid mill was taken as the mixture device.(3) The following conclusions were drawn through the single factor analysis:â‘ The cycle times of colloid mill influenced the test effect, it was not satisfied if few or more. Three cycle times was regarded the best.â‘¡The flow speed of the mixed liquid in the processor influenced the biodiesel productivity. The biodiesel productivity was low and the separation was not good if the flow speed surpassed 15ml/min in the processor. On the contrary, if the flow speed lower less than 5ml/min, the mixture liquid viscosity was relative high and not easy to flow through the processor, moreover pump's propelling force was also insufficient. Therefore it was better when the flow speed was 5¹5ml/min.â‘¢The PEF's pulse number and the pulse frequency influenced the biodiesel productivity. The productivity increased along with the pulse number's enhancement and reached the most when C=40. The productivity enhanced along with pulse frequency's enhancement and f=3000Hz was chosen in the equipment permission's scope.â‘£The PEF's intensity influenced the biodiesel productivity. The productivity increased along with the intensity's enhancement and reached the most when E=50KV/cm.⑤The related curves were drawn about pulse number , intensity and productivity. From the curves, it was found that the productivity increased along with the intensity and pulse number's enhancement, but the number's influence was primary. (4)The electric fields intensity, pulse number and the cycle times of colloid mill were studied and drawn the following conclusions through the orthogonal test analysis.The pulse number was the most important factor and was the extremely notable one which remarkable level was 0.01. Next was the electric field intensity which remarkable level was 0.1, and then was the cycle times which was not remarkable factor. The most suitable combination of A3B3C3 was chosen, and that was to say the pulse number was 40, the electric field intensity was 50KV/cm, the cycle times of colloid mill was 3.(5)A simplified regression equation was obtained by means of two general revolving unitized design which based on the orthogonal test. Y=95.05884 3.32864x₁+0.49592x₂-0.10917x₃ -2.19121x₁² -0.05221x₂² -0.61790x₃² -0.48750x₁x₂+0.23750x₁x₃+0.08750x₂x₃Used nonlinear analysis, Y reached maximum when x was 1.000, 1.682, 0.000 separately. The most suitable combination was that the pulse number was 45, the electric field intensity was 54.2KV/cm, cycle time of colloid mill was 3.Third, the PEF and the constant temperature oscillator were compared:(1) The comparison of the technological process:The technology used PEF was simple, continuous, time short, and was advantageous to the industrialization. Conversely the constant temperature oscillator was only suitable for the laboratory research.(2) The comparison of the facilitiesUsed PEF, the liquid flowed continuously, moreover the process need short time, low energy, and without capacity limited.(3) The comparison of the reaction termsBoth them not only had common parameters but also had differences. The PEF cost few time and less energy which only needed to heat in the beginning. Both methods had no obvious difference in productivity, using PEF could reach higher productivity such as above 96%.Fourth, the esterify mechanism was discussed:After good mixture, the soybean oil and methyl alcohol were unemulsified and polarized due to the effect of PEF. Because of shearing stress in the electric field, the liquid pellets film were broken and then polymerized and became large liquid pellets. The liquid mixture molecules were polarized and the conductance increased, then the free electric charges which were bound released, the entropy grew, and the confusion degree rose. Under the PEF's function, the entropy change's influence had surpassed the activation energy's response, also the PEF's influence to molecular, atomic, the electronic had surpassed energy factor such as density, temperature. The influence became very remarkable, and strengthened rapidly along with the parameters of PEF. The entropy change promoted the ester exchange response.