As discussed in Chapter 2, the ultrasound is one the crucial elements to enhance the ODS process. But in real life, ultrasound may consumption a lot of power, also, ultrasound device such as amplifier, sono-reactor and function generator are require higher capital cost. Therefore, to be able commercialize this ODS process, alternative mixing strategy is necessary to be develop, to see if ultrasound can be replace.As has been discussed in Chapter 2, to improve the ODS process, the ultrasound component is found to be crucial.
However, in actual life, it is possible for ultrasound to utilize a good deal of power. Moreover, such devices as amplifier, sono-reactor and function generator are prone to increase the capital cost. Henceforth, for the commercialization of the ODS process, it is essential that an alternative strategy be developed for chances to replace ultrasound.
This study compare four different kind of mixing strategy, which include, magnetic stir bar, motor stir, ultrasound and high shear mixer. Table AAA illustrated the desulfurization efficiency of Valley oil by four different types of mixing methods. Figure 123 shows the desulfurization efficiency of 4 different mixing methods.In the present study, four different mixing strategies are compared, which are, magnetic stir bar, motor stir, ultrasound, and high-shear mixer. Table AAA displays the desulfurization efficiency of valley oil by four different types of mixing methods. Figure 123 displays the desulfurization efficiency of 4 different mixing methods.Magnetic StirMotor StirHigh Shear MixerUltrasound900 RPM1,400 RPM10,000 RPMTimeConcentrationConcentrationConcentrationConcentration08,1008,1008,1008,100106,3806,0472,6676,741205,7814,1521,9845,114404,2193,4801,2083,741602,8741,7298112,2181401,8479143121,426200986471174691With different RPM, it clearly shows higher RPM will give higher desulfurization efficiency.
Compare with ultrasound desulfurization, (can you write about 8 to 9 lines to discuss from above data: (1) explain that ultrasound did not give better desulfurization efficiency compare to stir method. Therefore ultrasound can be replace by mechanical stir. (2) AT batch sale from chapter 4, sulfur concentration reduces to 187 ppm after 6 hours of stir and reduces to 12 ppm after 12 hours stir. With high shear mixer, it require almost half the time to reach that low sulfur concentration. From (1) and (2), it can conclude that mixing regime were very important to ensure aqueous and diesel phase can be perfectly mixed in order to achieve high efficiency desulfurization.It is clearly shown that different RPM speed will produce higher efficiency for desulfurization.
When compared to desulfurization, the following result were met. (1) As compared to the stir method, the ultrasound did not yield better desulfurization. Hence it is possible to replace the ultrasound with the mechanical stir. (2) From Chapter 4, at batch sale, concentration for sulfur diminishes to 187 ppm after it was stirred for 6 hours; it diminishes to 12 ppm when it was stirred 12 hours. However, with high-shear mixer, it requires half as much time to attain the low sulfur concentration.
From the observations above (1, 2), it can be concluded that it was essential to mix regimes to make sure that aqueous and diesel phase can be perfectly mixed to obtain desulfurization of high efficiency. From the experimental observation, with 10,000 rpm, after 10 minute, the entire mixtures become almost 95oC due to high shear mixing. With this temperature, hydrogen peroxide and acid catalyst may decompose, evaporate and lost its activity, because boiling point for hydrogen peroxide and trifluoroacetic acid were 106oC and 72oC respectively. To avoid the lose of row reactants, lower the reaction temperature were necessary, instead of 95oC, 50oC as the reaction temperature and 5,000 rpm as the mixing speed has been chooses as the new reaction condition. Figure AXC shows the desulfurization efficiency of two different reaction condition.
From the experimental observation it was obtained that with 10,000 RPM, after 10 minutes, due to high shear-mixing, all the mixtures reach up to 95oC. With this degree of temperature, it is possible for hydrogen peroxide and acid catalyst to decompose, evaporate, and lose their activity, because boiling points for hydrogen peroxide and trifluoroacetic acid were 106oC and 72oC correspondingly. To avoid the lose of row reactants, it was necessary to lower the reaction temperature. As such, instead of 95oC, as new reaction condition 50oC as the reaction temperature and 5,000 rpm as the mixing speed were choen. Figure AXC displays the desulfurization efficiency of two different reaction conditions. 10,000 rpm, 95oC5,000 rpm, 50oCTimeConcentrationConcentration08,1008,100102,667914201,984779401,208564608113141403128420017415Figure AXCResult from Figure AXC (write 8-9 lines of paragraph of following given info: (1) It clearly shows with 50oC as the reaction temperature, it shows better sulfur reduction than 95oC. (2) After 200 minutes, there is no weight loss of aqueous phase with lower operating temperature.
(3) In this operation condition, high sulfur content Valley oil can reduce to 15 ppm after three times liquid extraction. Although, it meet the new sulfur regulation.From Figure AXC, the following observations are met. (1) With 50oc being the reaction temperature, sulfur reduction is better than with that of 95oc. (2) Moving along the same line of our observation, it is found that after the span of 200 minutes, there is loss in the weight of aqueous phase with lower operating temperature. (3) In this operation condition, high sulfur content Valley oil can reduce to 15 ppm after liquid extraction was done three times although it meets the new sulfur regulations.