共查询到18条相似文献,搜索用时 109 毫秒
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分子蒸馏又称短程蒸馏,是在高真空条件下进行的非平衡连续蒸馏过程,综述了分子蒸馏的发展过程、基本原理、特点及其设备,同时对分子蒸馏在植物、动物药用部分及其他方面的应用进行了介绍。 相似文献
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分子蒸馏技术是近年来应用较多的一种新的分离纯化技术,具有蒸馏温度低、受热时间短、分离程度高等优点,在食品和化工制药行业应用较多.总结了近年来分子蒸馏技术用于中药有效成分精制的研究进展与方法,围绕分子蒸馏技术的基本原理与实际应用,探讨了该技术用于中药有效成分分离纯化的基本规律,分析得出分子蒸馏技术是一种精制中药有效成分的良好途径,在中药有效成分提取分离阶段使用分子蒸馏技术,特别适用于传统中药中高沸点、热敏性及易氧化的有效成分分离和纯化,分子蒸馏技术有利于促进中药有效成分分离技术的现代化. 相似文献
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建立了一种用蒸馏法富集水体样品中氨氮并联用离子色谱技术检测的方法。该方法可以有效富集水体中的氨氮(以NH4+形式),并去除水体样品中的Na+、K+及其他基质离子的影响。以IonPac CS16色谱柱为分离柱,用甲磺酸等度洗脱方式使待测组分分离,流速为1mL/min,电导检测,外标法定量。在优化后的实验条件下,NH4+的线性范围为0.01-50μg/mL,相关系数大于0.9991;将该方法应用于海水、湖水、苦咸水等水样的检测,实际样品加标回收率为86.8-106.8%,检测限为1.28ng/mL(信噪比S/N=3)。实验结果表明,该方法可以用于水体中氨氮的检测。 相似文献
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The work is devoted to design the globally linearizing control (GLC) strategy for a multicomponent distillation process. The control system is comprised with a nonlinear transformer, a nonlinear closed-loop state estimator [extended Kalman filter (EKF)], and a linear external controller [conventional proportional integral (PI) controller]. The model of a binary distillation column has been used as a state predictor to avoid huge design complexity of the EKF estimator. The binary components are the light key and the heavy key of the multicomponent system. The proposed GLC-EKF (GLC in conjunction with EKF) control algorithm has been compared with the GLC-ROOLE [GLC coupled with reduced-order open-loop estimator (ROOLE)] and the dual-loop PI controller based on set point tracking and disturbance rejection performance. Despite huge process/predictor mismatch, the superiority of the GLC-EKF has been inspected over the GLC-ROOLE control structure. 相似文献
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赵静 《工业仪表与自动化装置》2013,(6):50-54
精馏过程属于多变量、时变、强耦合和具有分布参数的非线性过程,为了实现精馏塔塔顶和塔底的产品均需达到一定纯度的要求,在分析精馏塔工作特性以及塔顶和塔底的温度耦合特征的基础上,提出了一种塔顶和塔底温度模糊解耦控制方案。通过对塔顶和塔底温度的PID控制、解耦控制、模糊解耦控制,进行了设定值扰动测试、过程扰动测试的仿真。结果表明,模糊解耦优于PID控制和解耦控制,验证了模糊解耦控制的可行性。 相似文献
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Jana AK 《ISA transactions》2007,46(1):49-57
A nonlinear adaptive control strategy is proposed for a binary batch distillation column. The hybrid control algorithm comprises a generic model controller (GMC) and a nonlinear adaptive state estimator (ASE). The adaptive observation scheme mainly estimates the imprecisely known parameters based on the available tray temperature measurements. The sensitivity of the proposed estimator is investigated with respect to the effect of initialization error, unmeasured disturbance and uncertainty. Then, a comparative study is carried out between the derived nonlinear GMC-ASE controller and a traditional proportional integral law in terms of set point tracking and disturbance rejection performance. The study also includes the effect of measurement noise and parametric uncertainty on the closed-loop performance. The proposed adaptive control algorithm is shown to be quite promising due to the exponential error convergence capability of the ASE estimator in addition to the high-quality control action provided by the GMC controller. 相似文献
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Industrial methanol production involves a multi component feed containing methanol, water and trace levels of ethanol being refined to produce AA grade methanol at high product recovery. Due to practical constraints, the bottoms discharge of the column is primarily water with only trace of methanol impurities. As a result of these constraints, ethanol, which is a non-key middle boiling component gets “trapped” near the side draw of the column forming an ethanol bulge, which in turn results in non-linear, inverse, time and state varying behaviour of the side draw ethanol composition. In this work, we established that the existence of the ethanol bulge creates the complex process behaviour of the side draw ethanol composition and that this bulge needs to be explicitly controlled. This type of explicit composition bulge analysis and subsequent control has not been attempted on methanol distillation columns before. For this purpose a novel, robust and practical side draw control scheme to detect and remedy the excess ethanol bulge movement using override control is presented. The side draw controller, together with other regulatory controllers is shown to maintain on-specification operations of the column. Disturbance rejection tests carried out illustrate that the side draw control scheme will keep the column operating within commercial specification. It is also shown that a traditional DV control structure is unable to achieve this objective. 相似文献
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In this paper, an artificial neural network (ANN)-based nonlinear control algorithm is proposed for a simulated batch reactive distillation (RD) column. In the homogeneously catalyzed reactive process, an esterification reaction takes place for the production of ethyl acetate. The fundamental model has been derived incorporating the reaction term in the model structure of the nonreactive distillation process. The process operation is simulated at the startup phase under total reflux conditions. The open-loop process dynamics is also addressed running the batch process at the production phase under partial reflux conditions. In this study, a neuro-estimator based generic model controller (GMC), which consists of an ANN-based state predictor and the GMC law, has been synthesized. Finally, this proposed control law has been tested on the representative batch reactive distillation comparing with a gain-scheduled proportional integral (GSPI) controller and with its ideal performance (ideal GMC). 相似文献
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分子影像学与蛋白质组学都是目前最前沿、最热门的医学研究领域。分子影像学通过先进的影像技术“在体”显示与疾病相关的分子改变,而蛋白质组学通过灵敏的体外检测技术分析与疾病相关的蛋白质组变化。将分子影像技术和蛋白质组学技术结合起来,很可能相互补充、相互促进,共同推动医学诊疗技术的突破。本文将在简要介绍分子影像学和蛋白质组学各自主要特点的基础上,分析二者相互结合的价值,并展望未来发展的方向。 相似文献
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根据共沸物组成随压力改变而变化的特性,设计了单塔可进行减压与加压两种操作方式的精馏装置,用于变压精馏分离乙腈-水的共沸物,以获得高纯乙腈。同时,应用西门子S7-300系列PLC及工业自动化监控组态软件iFIX,实现对乙腈变压精馏实验装置的实时监测和自动控制,控制系统运行稳定,实时性强,进一步提高了该精馏装置操作的安全性与便利性。装置及系统应用于化学工程与工艺专业本科生的实验教学及化学工程专业研究生的理论研究,效果优良。 相似文献