Venturi: hydrodynamic cavitation device to accelerate biodiesel synthesis

Abstract The objective of this work was to evaluate the potential of Venturi in the synthesis of biodiesel from residual edible oil in a methyl route. For this purpose, an experimental apparatus consisting of a 5.2 L tank and a Venturi device designed to produce the cavitation phenomenon was constructed in laboratory scale. Biodiesel production was evaluated at three different Venturi inlet pressures: 4.4; 2.9; and 1.4 bar. Methyl esters contents were determined by gas chromatography. Biodiesel synthesis time with the Venturi device was 23.2 seconds (or 4.5 seconds per liter of biodiesel produced), which is equivalent to a single cycle of the system at maximum pressure (4.4 bar). In this condition, the yield of the ester contents was greater than 98%. There is no other case of synthesis as fast as that found in this work. The biodiesel characterization showed that the parameters kinematic viscosity, acidity index, cold clogging point, and specific mass are within the limits established by National Agency of Petroleum Natural Gas and Biofuels (Agência Nacional de Petróleo). The use of Venturi, as a cavitation device, was shown to be more efficient in biodiesel synthesis than other devices, such as orifice plates.

摘要 本研究旨在评估文丘里（Venturi）装置在以甲醇路线利用废弃食用油合成生物柴油方面的应用潜力。为此，本研究搭建了实验室规模的实验装置，该装置包含一个5.2升储槽以及一套用于产生空化现象的文丘里设备。实验在三种不同的文丘里入口压力下开展：4.4 bar、2.9 bar与1.4 bar。采用气相色谱法测定产物中脂肪酸甲酯的含量。使用该文丘里装置的生物柴油合成总时长为23.2秒（即每生产1升生物柴油耗时4.5秒），对应系统在最大压力（4.4 bar）下的单次循环工况。在此工况下，脂肪酸甲酯的产率超过98%。目前尚未有其他合成工艺能达到本研究的反应速率。经表征，该生物柴油的运动粘度、酸值、冷滤点及密度均符合国家石油、天然气与生物燃料管理局（National Agency of Petroleum Natural Gas and Biofuels，Agência Nacional de Petróleo）制定的标准限值。相较于孔板等其他空化装置，文丘里装置在生物柴油合成中展现出更优异的反应效率。