超临界萃取技术在生物碱提取中的应用进展

超临界流体萃取技术具有选择性好、收率高、工艺简单、操作条件温和、绿色环保等优点,已被广泛应用于中草药的提取分离中。以生物碱的生物活性分类,综述了超临界萃取技术在各种天然生物碱提取中的应用研究现况及其特点。针对超临界萃取技术在提取生物碱中的发展前景及目前所存在的问题进行分析讨论。结果表明,它能够有效地从植物中提取或分离出生物碱,且与其它的分离手段相结合将是天然药物生物碱今后的提取分离发展方向。     

Current problems in the modelling of chemical reactors

Modelling of chemical reactors is reviewed with an emphasis on process development and scale-up. A distinction is made between modelling of chemical kinetics, of rate processes in volume elements and of whole reactors. Examples are mainly taken from papers presented at the Sixth International Symposium on Chemical Reaction Engineering. Special attention is given to the modelling of single phase reactors, fixed beds, trickle beds, fluid beds, and gas bubble reactors.     

陶瓷热压铸成型的超临界CO2流体脱蜡

利用超临界CO2流体萃取技术从陶瓷热压铸成型坯体中萃取有机粘合剂。对陶瓷热压铸成型中所使用的有机载体组分进行研究，对陶瓷热压铸成型超临界CO2流体脱蜡工艺条件进行了探索。研究了陶瓷坯体厚度、萃取压力，温度及时间对萃取率和陶瓷坯体脱蜡质量的影响。结果表明：由60％(质量分数，下同)非极性分子石蜡(熔点57℃)和40％极性分子蜂蜡(熔点58℃)组成的混合蜡作为热压铸浆料的有机载体，在压力为30MPa，温度为45℃的超临界CO2流体中脱脂可获得无缺陷的陶瓷热压铸成型生坯，脱蜡时间从34h减少到3h。由超临界CO2流体脱蜡后烧成的陶瓷试件具有小的变形及高的致密度。     

Biomass pyrolysis in a circulating fluid bed reactor for the production of fuels and chemicals

An approach for biomass flash pyrolysis in a circulating fluid bed (CFB) reactor with continuous solids regeneration is described in this study. The unit is capable of performing conventional and catalytic biomass pyrolysis with the proper solid selection. The production of improved quality liquid products in a direct step through catalytic pyrolysis is investigated in this work. Both conventional and catalytic biomass pyrolysis can be effectively performed in this CFB unit. Flash pyrolysis conditions were achieved and liquid product yields of ∼70 wt% (on biomass feed) were obtained. The effect of specific operating variables including the type of inorganic solid material and the solid/biomass ratio was established on the final liquid product quality and yield. Solid materials considered included silica sand, a commercial fluid catalytic cracking catalyst and a ZSM-5 additive. Catalytic biomass pyrolysis generally leads to the production of additional water, coke and gases compared to conventional pyrolysis. However, the obtained liquid product quality and composition is improved.     

东河储层损害机理分析

钻井液和酸化体系与储层流体不配伍是造成油层损害的主要原因。东河砂岩含有不同类型敏感性矿物,利用常规钻井液和酸化技术难以达到保护储层的目的。本文在分析东河储层敏感性损害机理前提下,提出保护油层的2项措施。     

水电站进水塔动水压力研究和探讨

基于理想流体,将进水塔简化成水中悬臂梁体系,推导了其受迫振动时的动力响应方程,给出了进水塔内外表面动水压力的解析表达式。与有限元法、水工抗震规范公式计算结果进行了对比,分析验证了该方法在进水塔结构上的适用性及准确性。结果表明:动水压力表达式与结构振型密切相关。该方法的动水压力曲线趋势与有限元方法相似,均在水面以下某深度处迅速变大及达到最大值后曲线值减小弯回,两者最终在塔体底部收于相近的值;最大值大于有限元法,其最大值处曲线折回明显,幅度较大。弹性模量和进水塔高度对动水压力的曲线形态和数值有重要影响。同时,输入激励荷载的频率对动水压力影响巨大,尤其频率与进水塔某阶频率相近时会导致动水压力的异常增大。该方法对分析进水塔动水压力具有参考价值。     

固体颗粒对三相气升式环流反应器流动特性的影响

将液相视为连续相,气相和固相视为分散相,同时考虑各相之间的相互作用,结合气液固三相流体的动力学理论,建立气液固三相环流反应器三流体湍流流动的Eulerian模型.采用计算模拟软件Fluent对三相环流反应器的流动状况进行模拟,考察表观气速、固含率、颗粒大小对反应器的气含率以及液体流动速度的影响.模拟结果较好地解释了气升式环流反应器内的三相流体行为,模型与实验结果较好地吻合,表明了模型的可行性.     

固体硫在超临界/近临界酸性流体中的溶解度(Ⅰ)实验研究

建立了1套静态法测定难挥发物质(固体或液体)在超临界/近临界流体中溶解度的实验装置,并测定了固体硫在近临界硫化氢、超临界CO_2、CH_4及富硫化氢酸性气体混合物中的溶解度数据,取得了较好的结果.     

The influence of fluid elasticity on wall effects for creeping sphere motion in cylindrical tubes

Experimental results are presented of wall effect for the slow motion of spheres in elastic, constant-viscosity liquids. The results are correlated in terms of diameter ratio for d/D < 0.3, and Weissenberg number We < 5. Weissenberg number is defined as We = 2θV_m/d, with θ the Maxwellian relaxation time (θ = N₁/2τγ). The wall effect is found to be adequately described by Newtonian expressions for small Weissenberg number, We < 0.01. For larger values of the Weissenberg number, We > 0.2, virtually no wall effect is discernible; the small effect observed is correlated by the wall factor expression The wall effect observed is ascribed to the influence of fluid elasticity alone, since all the fluids used were elastic to a greater or lesser extent, but showed no shear thinning.      

超临界流体技术应用研究

超临界流体技术具有许多传统技术所没有的快速，高效，低能耗，污染少等优点，在材料制备，医药工业，生物工程，食物，环境，化工等许多方面展现了广阔的应用前景。综述了其在萃取，材料制备和作为反应介质等方面的应用。