超临界流体萃取大蒜油的工艺研究

对温度、时间、压力对超临界二氧化碳萃取大蒜的影响进行了研究，通过正交试验得到最佳的工艺条件，并对试验所得产物进行测定。     

Investigation of the stability of tablets prepared from sucrose and citric acid anhydride utilizing response surface methodology

Inversion of sucrose is a stability problem particularly of candies with acidic taste that contain sucrose and small amounts of organic acids such as citric acid, since the free d-fructose produced by hydrolysis is hygroscopic. The following possibilities were investigated for preventing the hydrolysis of sucrose in tablets containing sucrose and citric acid: Adding various amounts of tri-sodium citrate to the formulation to neutralize the citric acid, (Hot) melt coating of citric acid and tri-sodium citrate with a vegetable fat at different coating ratios, variation of the ratio of coated citric acid and tri-sodium citrate in formulations, and compressing the formulations with different compression forces. After tablet processing and storage of tablets, the concentration of d-fructose was determined on the basis of enzymatic reactions. A response surface central composite design was used. The above-mentioned variations were chosen as independent variables and the amount of d-fructose was chosen as response variable. The lowest rates of inversion could be achieved by increasing the content of tri-sodium citrate and the ratio of coating material and decreasing the ratio of coated citric acid and tri-sodium citrate in the tablet formulations. The compression force had no significant effect on the inversion of sucrose.     

基于CFD的新型加香加料机布风系统的设计及改进

在新型烟草加香加料设备研制过程中,为解决多管送风导致孔板布风不均的问题,采用计算流体力学(Computational Fluid Dynamics,CFD)软件Fluent对原设计结构中的流场进行了仿真研究.仿真结果表明,布风室内气流合流产生的漩涡和筒内不良气泡特性的产生是导致布风不均的主要原因,对此提出了加装隔板分割布风室、对各布风室独立送风的改进措施.试验数据表明,改进后布风室两侧进风管道的风速差由2.1,1.5,14 m/s降低到0.5,1.3,1.0 m/s,阻止了布风室内涡流和加香加料筒内不良气泡特性的产生,改善了筒内气固两相混合的均匀性和规律性.     

流化催化裂化脱硫添加剂的研究进展

阐述了ＦＣＣＵ再生器中的ＳＯｘ的来源和控制方法,介绍了催化法控制ＳＯｘ排放原理和对Ｄｅ－ＳＯｘ添加剂性能的要求,综述２０多年来Ｄｅ－ＳＩｘ技术的发展以及添加剂开发和应用情况。     

用有限元方法合理设计磁流体密封结构

本文利用有限元数值计算方法对磁流体密封结构进行了分析。在对磁流体单级密封齿形研究基础上,提出了一种新型多级密封齿形结构。经计算其密封压差能比传统的矩形密封齿形结构提高十几个百分点,最后给出了具有这种新齿形“磁回路”各参数设计的取值范围。     

基于流固耦合的南水北调渠道结构动力破坏机理研究

以南水北调中线渠道工程为研究对象,建立了水体-结构-地基耦联体系的渠道模型,运用Fluid 30单元实现水工结构流固耦合计算,计算了地震工况下的渠道结构的破坏情况。计算结果与Westergaad传统方法进行对比,验证了Fluid 30单元方法的正确性。研究结果表明,Fluid 30单元耦合方法计算的结构频率均值较传统方法增加10. 93%,渠道结构进行地震分析时,水体的流固耦合效应不容忽视;渠道衬砌板分缝处为最薄弱部位,且出现了应力集中,每个纵缝处下表面均出现了较大的拉应力;衬砌结构在地震中可视为做整体移动,衬砌上表面比下表面所受的压应力更大,而在接近分缝处这一情况恰好相反。     

超临界流体及其在萃取中的应用

综述了超临界流体、超临界流体萃取技术及其在工业生产中的应用等,着重介绍了超临界流体萃取的原理和萃取装置,并对超临界流体萃取的发展新趋势作了分析。     

Kinetic modeling of FCC process

Catalytic cracking of petroleum fractions a process termed as FCC is usually carried out in a reactor block with somewhat complicated hydrodynamic regime. The reactor block is considered as a combination of two different reactors. The riser is a near ideal plug-flow displacement of the catalyst and reaction mixture, while the main reactor vessel (separator) is considered as an ideal mixing CSTR. Temperature gradient along the plug-flow riser can vary on a linear and non-linear dependence. This is reflected by the thermal effect on the cracking products, along the altitude of the riser. Moreover, it can exert a considerable influence on the selectivity of the process in general, as characterized by the diversity of different hydrocarbon groups both in the gaseous and liquid products. The fluid catalytic cracking (FCC) is a process of conversion of a heavy oil fraction into lighter products in a catalytic fluidized reactor. The chemical composition and the structure of the feed are reflected on the catalyst's selectivity and the amount of coke deposited. It is, therefore, necessary to consider the feed type on modeling the process. Cracking reaction in the model was represented as a five-stage process. Reaction rates for the plug-flow riser and the ideal mixing separator are described mathematically in differential and algebraic forms. The model takes into account, exponential dependence of the specific reaction rate on temperature, as well as reflects the influence of the real and bulk catalyst densities, circulation rate, equilibrium and fresh catalyst's activities, reactor pressure, feed rate and unit construction. The model was developed based on a data taken from an industrial FCC unit, that were used to compute the kinetic constants and other parameters. Concrete computed kinetic parameters were compared with corresponding experimental data for adequacy. FCC process is in constant technological development with modernization of especially the riser reactor. Kinetic modeling of the catalytic FCC reactor will give a further understanding of the process and explain the complicated mechanism involved for an efficient and optimal conversion of the feed stock.     

填料塔在高压蒸馏中的应用

高压蒸馏与真空和常压操作相比,填料塔中的气液均匀分布变得更加困难,并导致气相返混增加,填料分离效率下降,但经过适当的设计,填料塔不但可以提高高压蒸馏的生产能力,而且效率也得到提高。文中介绍高压蒸馏填料塔的特点和近年来的研究进展,并总结了国内外高压蒸馏填料塔新塔设计和老塔改造的成功经验。