超临界CO_2萃取木香挥发油的实验研究及数值模拟

Experimental Study and Simulation of Supercritical CO_2 Extraction for Essential Oil from Aucklandia Lappa Decne

采用单因素法,在流量2～4 L/min,木香颗粒度0.144～0.200 mm,萃取温度33～48℃,萃取压力10～25 MPa的范围内,利用超临界CO2萃取木香挥发油,分别考察了CO2流量、原料颗粒度、萃取温度及萃取压力等因素对挥发油萃取收率的影响;并根据萃取器微分单元和固态原料颗粒微分单元的质量守恒建立了微分方程,对一定萃取条件下的实验结果进行数值模拟。结果表明:在实验范围内,木香挥发油萃取收率随CO2流量增加而增大,随原料颗粒度减小而增大,随压力升高而增大,随温度则呈现出交叉现象。结论:CO2流量、原料颗粒度、萃取温度及萃取压力等对木香挥发油的超临界CO2萃取工艺有显著影响,所建立的数值模型能较好地描述实际萃取行为。

Experiments were carried out in the ranges of 2-4 L/min CO2 flow rates,0.144-0.200mm feed particle sizes,33-48 ℃ temperatures and 10-25 MPa pressures.A mathematical model of the supercritical extraction process was developed on the basis of the differential mass balances performed along the extraction bed and the feed particle.Results show that the extraction curves were dependent of flow rate and feed particle size in a plot of oil yield versus extraction time.This indicated that the extraction process is influenced by both intraparticle diffusion and film mass transfer.In the case of temperature effect,a crossover effect was observed.The extraction rate increased as the pressure increased due to an increase in the solvent density.The results show that the CO2 flow rate,feed particle size,temperature and pressure affect the oil yield remarkably and that the mass transfer of the present system could be well described by the model employed herein.