两步扩散模型对超临界CO2萃取丁香油的数值模拟

基于扩散模型方程和集总参数模型方程,首次建立了具有3个可调参数的两步扩散模型方程.该模型同时考虑固体颗粒内扩散阻力与内壁的阻力,能较好地描述超临界流体萃取过程.用两步扩散模型方程模拟了超临界CO<,2>萃取丁香油的动态过程,在实验温度与压力范围内模型计算值与实验数据的平均相对误差AARD在2.33%～19.48%之间,...     

超临界CO2萃取丁香油的数值模拟

为了预测超临界CO₂萃取挥发油动态过程,根据挥发油在超临界CO₂与物料之间的质量传递平衡,采用集总参数法建立超临界CO₂萃取丁香油过程的数学模型。结合不同温度、压力、粒径和CO₂流速条件下的实验结果,对方程进行了合理的简化,并利用实验数据拟合出模型中CO₂密度、粒径和流速的系数。验证结果表明模型的计算值和实验值的平均相对误差在6. 88%～57. 78%之间,建立的数值模型能较好地描述实际的超临界CO₂萃取丁香油行为。     

丁香油的超临界CO2萃取及其微胶囊的制备

在70℃和10 MPa条件下通过对丁香花蕾进行超临界CO2萃取得到丁香油,萃取率达19%～21%.气质联用分析结果表明,丁香油中主要化学成分包括丁香酚、β-石竹烯和乙酰基丁香酚等.以丁香油为囊芯,探讨利用干酵母细胞作为囊壁材料制备微胶囊的可行性.通过正交试验考察了包埋温度、包埋时间、丁香油与干酵母配比(芯材比)对微胶囊化丁香油的影响.结果表明,在包埋温度70℃、包埋时间9 h和芯材比为1∶1(w/w)的条件下,微胶囊中丁香油包埋率达到41.26%.通过扫描电镜观察,丁香油微胶囊呈规则的球形,大小均一,颗粒直径在2.0～4.0 μm.在100℃下对经微胶囊化的丁香油加热20 h,其挥发率只有15.04%,远低于相同条件下丁香油的挥发率(58.29%).这种新型的微胶囊化方法,具有制备过程简单、包埋率高和不引入有机溶剂的优点.     

超临界CO2萃取生姜油实验研究与数值模拟

利用自建的超临界流体萃取实验装置,以CO2为萃取剂,考察了萃取压力、温度、流体流量及原料颗粒度等因素对生姜油累积萃取率的影响,由此确定了较佳的萃取工艺条件。基于萃取器微分单元质量守恒原理,建立了数学模型,并利用直线推动力近似理论拟合了总传质推动力及平衡吸收常数,对实验结果进行了数值模拟。     

超临界CO2萃取胡椒油实验研究与数值模拟

建立了超临界流体萃取胡椒油实验装置,以CO2为萃取剂,考察了萃取压力、温度、CO2流量及原料颗粒大小等因素对胡椒油萃取率的影响,并由此确定了较佳的萃取工艺条件:压力22—26 MPa,温度313—323 K,胡椒颗粒度30—40目,CO2流量0.3—0.4 m3/h,胡椒油累积萃取率可达80%—90%。基于萃取器微分单元和固态原料颗粒微分单元质量守恒原理,建立了微分方程,利用直线推动力近似理论拟合总传质推动力及平衡吸收常数,化简方程,对实验结果进行了数值模拟。     

超临界CO2萃取的研究进展

超临界CO2流体萃取技术是近年来兴起的一项具有精馏和萃取两过程的高新物质分离精制技术，文章主要通过对各类超临界CO2流体萃取实验的文献报道和实验操作进行分析，对超临界CO2流体革取技术的原理、特点和超临界CO2流体萃取的主要影响因素及其优化方法和经验模型进行了综述。     

固态物料超临界CO2萃取的传质模型

对超临界CO2萃取固体物料的过程进行了机理分析,在分子缔合理论的基础上建立了描述超临界CO2流体萃取固态物料传质特性的数学模型,确立了用于估算超临界CO2流体萃取固态物料颗粒所需时间的方法,并提出了宏观萃取速率表达式,实现了超临界萃取过程研究的计算机化,既可从过程的静态和动态特征寻求适当的操作和控制,实现过程的数学模拟放大,有助于投资前的经济预算,有效减小投资风险,也可作为超临界CO2萃取过程的研究手段,减少实验探索的工作量。     

超临界CO2萃取的研究进展

通过对各类超临界CO2流体萃取实验的文献报道和实验操作进行分析,对超临界CO2流体萃取技术的原理、特点和超临界CO2流体萃取的主要影响因素及其优化方法和经验模型进行了综述.     

超临界CO2萃取沙棘油的实验研究及数值模拟

本文利用超临界CO2萃取沙棘油,建立了一套实验流程,分别考察了萃取压力、萃取温度以及颗粒大小对萃取率的影响。同时根据萃取器单元的质量守恒建立了微分方程,并对一定萃取条件下的实验结果进行数值模拟。结果表明,本文所建立的数值模型能较好地描述实际萃取行为。     

Influence of the bed geometry on the kinetics of the extraction of clove bud oil with supercritical CO2

There is a need for scientific research that evaluates the influence of important process variables on the scale up of supercritical technology. For supercritical fluid extraction (SFE), one of these variables is the extractor's bed geometry, which can be defined by the ratio of the bed height (H_B) to the bed diameter (D_B). A systematic study is needed to select suitable criteria that can be used to obtain similar extraction curves among beds with different geometries. In this study, maintaining a constant ratio of solvent mass to feed mass for two beds with 1-L volumes but different geometries (E-1: H_B/D_B = 7.1; E-2: H_B/D_B = 2.7) was confirmed as a successful scale up criterion. For constant values of the temperature, pressure and bed porosity, there is experimental evidence that the mass transfer rate is equal in the two beds when the solvent flow rate is high. When 0.6 kg of clove buds was packed in the beds, the extraction rates were 2.10 ± 0.08 and 2.3 ± 0.1 g extract/min for beds E-1 and E-2, respectively. However, when the solvent flow rate was lower, the extraction rates were 0.93 ± 0.06 and 1.12 ± 0.02 g extract/min for beds E-1 and E-2, respectively. This difference in behavior between the extraction beds is associated with the axial dispersion of the fluid, which is more pronounced when the H_B/D_B ratio is increased. Thin particles tend to compact in the beds with high H_B/D_B ratios, which shorten the solvent passage. Non-isothermal profiles and differences in chemical composition of the extracts were also observed: 17% more α-humulene and 9% more eugenol were extracted in E-1 and E-2, respectively.     

超临界CO_2萃取辣椒油实验研究

研究了利用超临界CO2为萃取剂,从辣椒中萃取分离辣椒油的工艺。考察了萃取压力、萃取温度、辣椒原料颗粒大小以及CO2流量等因素对辣椒油萃取率的影响。结果表明,最佳工艺参数为:压力22 MPa,CO2流量0.3~0.4 m3/h,颗粒度30~50目,温度315 K。超临界萃取法具有工艺简单、操作安全、产品无溶剂残留、提取率高等优点。     

Petroleum-free extraction of oil from soybeans with supercritical CO2

Full-fat soyflakes are readily extracted with supercritical carbon dioxide (SC-CO₂) at pressures of 3,000~10,000 psig and 50 C. Under these conditions, SC-CO₂ has the density of a liquid and the diffusivity of a gas. Therefore, equilibrium solubility is readily achieved in a short-path batch extractor which permits high gas flow rates. Soybean oil extracted with SC-CO₂ is lighter in color and contains less iron and about one-tenth the phosphorus of hexane-extracted crude oil from the same beans. The lower phosphorus content is reflected in a chromatographic refining loss of 0.6% compared to 1.9% for hexane crude. Refined oils from hexane and SC-CO₂ extraction had equivalent odor and flavor scores initially and after 4 days' storage at 60 C. Carbon dioxide, an ideal solvent for extraction of food products, is low-cost and readily available from fermentation processes and could free over 20 million gallons of costly hexane per year for essential energy uses.     

Effects of supercritical CO2 extraction parameters on soybean oil yield

A series of operational parameters of supercritical fluid extraction of soybean oil (pressure: 300–500 bar, temperature: 40–60 °C, CO₂ mass flow rate: 0.194–0.436 kg/h and characteristic particle size: 0.238–1.059 mm) were investigated in a laboratory scale apparatus. The results show that the extraction yields were significantly affected by applied operational extraction parameters. The increase in pressure, temperature and solvent flow rate improved the extraction yield. The extraction yield increased as the particle size decreased depending on decreasing intra-particle diffusion resistance. To describe the extraction process Sovova's model was used and very good agreement with the experimental results was obtained. Based on the experimental data the internal and external mass transfer coefficients were estimated. To explore the influence of the extractor size on this process, soybean samples were extracted using different extraction basket volumes (0.2 L and 5 L) and related model parameters were examined. The mass transfer coefficient in the fluid phase increased with the increase in extractor size, while the mass transfer coefficient in the solid phase was independent of the extractor size.     

超临界CO_2萃取分离桔油中的萜烯和含氧化合物

以冷榨柑橘精油为原料,采用GC/MS对柑橘精油原料进行定性及定量分析,确定了柑橘精油中的7种萜烯类化合物成分作为分离考察对象。实验探讨了超临界萃取压力、萃取温度、萃取时间和CO2流量等因素对含氧化合物分离效果的影响。实验结果表明,萃取相中萜烯类化合物的回收率总体上随着萃取压力、温度、时间和CO2流量的增大而增大。当萃取压力为12MPa,萃取温度为45℃,萃取时间为4h以及CO2流量为1.0L/min时,分离效果最佳,其萃取相中萜烯类化合物的回收率高达90.03%。     

Enrichment of omega3 fatty acids from Tyulka oil by supercritical CO2 extraction

BACKGROUND: Supercritical CO₂ enrichment of omega3 essential fatty acids (FAs) from Tyulka oil, using a batch process was investigated. Fractional factorial design was applied to evaluate the effects of the five process parameters: pressure (20.26 to 25.33 MPa); temperature (40 to 50 °C); packing fraction (0.5 to 0.7); modifier fraction (2 to 5%); and dynamic time (15 to 25 min), and their binary interactions on the enrichment of extracted omega3 FAs. By employing experimental design and analysis of variance, the variables were evaluated according to the significance of their effect on the yield of extracted omega3. RESULTS: The experimental results confirmed that pressure and dynamic time were the most important factors affecting enrichment of omega3. The amount of modifier in the feed also showed an increasing effect on the response. The binary interaction effects were investigated, and are discussed in detail. CONCLUSION: Optimum conditions were found at 25.33 MPa, 46.65 °C, packing fraction 0.50, modifier 5% and dynamic time 25 min, improving the enrichment of omega3 FAs up to 2.9 times. Copyright © 2009 Society of Chemical Industry     

Mathematical modeling of extraction of egg yolk oil with supercritical CO2

Extraction of egg yolk oil (EYO) from egg yolk powder (EYP) with supercritical CO₂ was performed on a laboratory apparatus. Solubility of EYO in supercritical CO₂ was measured. The external diffusion and the equilibrium between solid and fluid phases were experimentally found to be the controlling steps during the extraction process. Based on this mechanism, a mathematical model for this extraction process was developed. The model parameters, adsorption equilibrium constant (k_p), EYO concentration in solid controlling the transition in the equilibrium (x_k) and the overall volumetric mass transfer coefficient (K_fa_p), were obtained by simulation. The simulation results indicated that x_k is 0.56, K_fa_p is directly proportional to CO₂ flow rate with an exponent of 0.548, and the adsorption heat of EYO is 6–9 kJ mol⁻¹. The model was verified by concentration profiles of solid. The extraction process of EYO with supercritical CO₂ was conducted on a pilot plant and the developed model could predict satisfactorily the process.     

超临界CO2萃取辣椒油的工艺条件优化研究

以三峡库区种植的辣椒为原料,采用超临界CO2萃取技术,从辣椒中提取辣椒油,考察了萃取温度、萃取压力和萃取时间对辣椒油萃取率的影响。结果表明,萃取温度对辣椒油的萃取率影响最大,其次是萃取压力,萃取时间影响最小;超临界CO2萃取辣椒油的最适宜条件为,萃取温度40℃,萃取压力10 MPa,时间75 min,其萃取率为9.37%;超临界CO2萃取技术应用于辣椒油的提取具有工艺简单、操作安全、能耗低、无毒、萃取剂易回收、萃取率和产品纯度高等优点。     

Mathematical modeling and genetic algorithm optimization of clove oil extraction with supercritical carbon dioxide

In the present study, a mathematical modeling for extraction of oil from clove buds using supercritical carbon dioxide was performed. Mass transfer is based on local equilibrium between solvent and solid. The model was solved numerically, and model estimation was validated using experimental data. For optimization, the clove oil equilibrium constant between solid and supercritical phase was determined by a theoretical method using fugacity concept, consequently the genetic algorithm for obtaining optimal operational conditions was used. The optimal conditions which obtained the highest amount of clove oil were pressure of 10 MPa and temperature of 304.2 K.