考虑冷凝器泄漏的精馏塔动态模拟与分析

精馏塔的动态模拟已被广泛用于开发有效的控制方案。以甲醇-水体系为例建立了精馏塔的动态模型,并用换热器准确的表达塔顶冷凝器与塔底再沸器;运用Aspen Dynamic对精馏塔冷凝器发生泄漏的工况进行模拟,分析了塔顶与塔釜流量与组成、回流比、冷凝器和再沸器负荷等参数的动态响应特性,其结果可用于精馏塔操作中的故障诊断,并可为控制方案设计提供依据。     

精对苯二甲酸装置溶剂脱水塔水相回流对分离效果影响的研究

在醋酸脱水共沸精馏系统中,水相回流不仅能调节物料平衡,而且能控制塔顶出料中的醋酸浓度.在醋酸脱水系统设计和控制的研究中,水相回流往往给定一个固定的流量,很少被用作控制变量,水相回流与精馏塔的进料变化及出料组成的关系未见报道.本文利用Aspen Plus流程模拟软件模拟计算精对苯二甲酸(PTA)装置溶剂脱水共沸精馏系统.利用三元相图分析醋酸-水-醋酸正丁酯(HAC-H2O-NBA)体系中,进料组成变化与水相同流和酯相回流之间的关系.在稳态模型的基础上模拟分析进料中水含量和杂质对二甲苯(Px)对水相回流的影响,结果与相图分析一致.研究结果表明:对于某一特定的出料要求,当进料水含量高于69%时,水相回流可以降低为零,如果此时进料组成发生变化,只要调节酯相回流即可保证精馏塔的分离要求,而当进料水含量低于69%时,水相回流需要进行调节以保证塔顶采出水中醋酸含量合格:不能让杂质PX在塔内累积过多,以免因水相回流大量增加而使塔的能耗增加.本文的研究很容易扩展到其它具有特定出料要求的醋酸脱水共沸精馏系统中,研究结果将为实际生产过程中精馏塔出料组成和能耗的控制提供参考.     

分隔精馏塔分离烷烃混合物的模拟

提出采用分隔精馏塔替代常规精馏塔分离烷烃混合物的新工艺。通过Aspen模拟和灵敏度分析,着重探讨分隔精馏塔中进料位置、回流比、连接流的位置、回流气液分配比等工艺参数对分离效果和热负荷的影响,并确定分隔精馏塔的最佳操作条件是。结果表明,分隔精馏塔单塔就能达到常规的烷烃分离要求,但是对精馏塔的控制要求更高。能耗分析表明分隔精壁塔工艺比传统的分离过程节能45%。     

乙烯基降冰片烯减压精馏系统的模拟与优化

汽相采用Virial方程,液相采用Wilson方程汽液平衡模型,对乙烯基降冰片烯（VNB）合成液减压精馏系统建立了复杂精馏塔的数学模型,采用严格的三对角矩阵法编制了适用于非理想完全互溶体系精馏塔模拟计算程序,经过模拟与优化计算,得到了达到分离要求（塔顶VNB含量≥99％）精馏塔最佳回流比、最适宜进料板序数、最佳全塔理论塔板数等的操作参数,模拟计算结果与实验结果相吻合,证明该模拟系统准确可靠,从而为乙烯基降冰片烯（VNB）合成液减压精馏系统工程设计提供了依据。     

进料位置对双组分精馏过程耗能原因的分析

利用Aspen Plus软件对正庚烷-正辛烷双组分物系的精馏过程进行模拟计算。通过灵敏度分析确定最小回流比和理论板数的基础上,考察精馏塔的进料板位置、回流比等因素对分离精度、塔内气液相组成、温度分布和能耗的影响,结果表明,固定总板数和进料板位置,随着回流比的增加,塔顶产品组成随之增加;回流比改变,最优进料板位置也会发生变化;在达到分离要求的情况下,随着进料板位置的下移,塔顶热负荷、塔底热负荷和总热负荷先降低后升高;在最优进料板进料时,进料气液相组成和温度分布与进料板上的气液相返混程度和温度返混最小,每块塔板均为有效板,具有较高的分离能力,此时能耗最小。     

萃取精馏法分离正丁醇-异丁醇的模拟和实验研究（英文）

采用连续侧线出料精馏法对原料进行预处理,切取正丁醇-异丁醇富集液。采用色谱法在汽液平衡釜上探索正丁醇-异丁醇在溶剂中的分配效果,选择甘油为最适合的萃取溶剂。运用Aspen Plus模拟软件对正丁醇-异丁醇萃取精馏塔进行过程模拟,考察了蒸馏流率、理论塔板数、原料和溶剂的进料位置、回流比、溶剂比对正丁醇异-丁醇混合物分离效果的影响。通过正交化设计优化和验证实验,得到最佳萃取精馏塔的操作条件,即蒸馏流率D9=17 kg/br,理论塔板数N=49,原料进料位置NF--29,溶剂进料位置NS=8,回流比R=6,溶剂比S:F=11:1。研究结果表明在最佳操作条件下,塔顶异丁醇纯度可以提高到99.80%,得率为89.38%,塔底正丁醇纯度可达到97.53%,得率为99.96%,验证实验结果与模拟结果相对误差小于1%。研究结果为进一步实验研究提供基础参数。     

莱文伯格-马夸特算法的精馏动态模拟

本文研究了以神经网络理论为核心的精馏塔的动态模拟。结合牛顿全局优化的思想,在多层前馈BP神经网络的基础上,提出一种Levenberg-Marquardt优化神经网络算法,应用于甲醇精馏塔的动态模拟。模拟结果表明,进料组成影响着塔顶的气相组成和塔底的液相组成;稳态因组分变化而破坏后,塔顶的气相流率和塔底的液相流率都发生变化,最后达到新的平衡;当进料组成、回流比发生很小变化时,甲醇精馏塔的平衡状态影响较大。     

丙酮和正己烷共沸体系萃取精馏的模拟优化

利用化工流程模拟软件Aspen Plus以NMP为萃取剂对丙酮和正己烷共沸物系的双塔连续萃取精馏过程进行了模拟计算与优化。确定最优工艺方案为:萃取精馏塔理论板数32,正己烷与丙酮原料进料位置为第25块理论板,萃取剂进料位置为第4块理论板数,溶剂比1.8,回流比1;溶剂回收塔理论板数为7块,回流比为0.6,进料位置为第4块理论板数。萃取精馏塔塔顶产品正己烷含量达到99.84%,萃取剂回收塔塔顶丙酮含量达到99.88%。模拟和优化结果为分离过程的优化操作和设计提供理论依据。     

基于Aspen Plus的聚甲氧基二甲醚精馏过程模拟分析

在装有θ环填料的精馏塔内进行了聚甲氧基二甲醚精馏实验。利用化工流程模拟软件.AspenPlus对聚甲氧基二甲醚精馏过程进行模拟,首先,采用DsTWU简捷蒸馏模型,运用软件中NRTL、WILSON、UNIQUAC,3种物性方法对精馏塔进行了计算,得到了回流比、塔板数和温度等操作参数。接着,采用RadFrac严格精馏模型对精馏塔进行了验证,其计算结果与实验结果吻合良好,满足工艺要求。最后,对精馏塔的操作变量进行了灵敏度分析,讨论了进料位置、进料流率和回流比等参数对精馏分离要求与能耗的影响,并确定了最优化方案,即:进料板为第50块,进料流率为35 mol/h,回流比为6。     

新戊二醇间歇精馏过程的模拟、优化与应用

应用PRO/II化工模拟软件对新戊二醇(NPG)精馏过程进行模拟,模拟结果与实际生产数据相吻合,相对误差在0.80%~3.85%之间。模拟分析了蒸馏时间、回流比、蒸汽流量等参数对新戊二醇精馏过程的影响规律,提出了减少塔顶馏出液中新戊二醇含量、精馏时间的工艺优化方案,与原生产工艺相比,塔顶馏出液中NPG的损失量由1.13%降至0.80%,精馏时间可缩短1h。以工艺优化方案一为依据对生产装置进行改造,改造后与改造前相比,精馏时间缩短了0.4h。     

Low and moderate alcohol doses,psychomotor performance and perceived drowsiness

To investigate the role of alcohol on reaction time, performance errors and perceived drowsiness, 26 subjects were tested on a step input tracking task combined with a divided attention test. In four sessions in which varying amounts of alcohol were consumed it was found that as the mean blood alcohol concentration (BAC) rose from 0 to 0·073%, the number of errors increased significantly. Also, subjects reported being drowsy for at least 3 hours after drinking moderate amounts of alcohol (mean BAC, 0·050 to 0·073%). The results of the study are discussed in relation to alcohol induced driving impairment.     

烷烃、芳香烃、醇表面内力与其各能量项的相关关系

采用hyperchem 7.5软件,分别在4种力场(Amber、Opls、MM++、Bio+)下模拟了烷烃类、芳香烃类、醇类物质的能量项:总能量(total energy)、键能(bond)、角度(angle)、二面角(dihedral)、范德华作用能(vdw)、扭转力(stretch-bend)、势能(epot).用Origin软件,分析了上述物质不同力场下各种能量项与表面内力的相关性,结果表明在4个力场下范德华作用能(vdw)与表面内力的相关性最佳.同时通过SAS软件对上述物质建立数学模型(多元线性回归方程),该回归模型表明在Bio+力场下,各能量项与表面内力的相关性最佳,表面内力计算值与实验值相关系数可达0.8777.通过这些分析,我们不仅描述了各能量项与表面内力的相关性,同时开辟了一种理论角度研究表面内力的方法.     

Physiological costs of the hearing due to noise exposure,additional physical stress,and combined exposure to alcohol and cigarette smoke

In 2 studies, each with 5 test series, physiological costs of the hearing due to legally tolerable noise exposures of 94 dB (A) for 1 hr have been measured audiometrically. The temporary threshold shifts (TTS) and their restitution time, as well as cardiovascular responses in work‐related heart rate increases, of 10 and 8 subjects (Ss), respectively, could be shown to be modulated by additional physical stress and combined exposure to alcohol (Study 1) and cigarette smoke (Study 2). Moderate dynamic muscle work (50 W) administered via a bicycle ergometer either immediately after noise, or simultaneous to the noise exposure, significantly reduced restitution time as well as the integrated restitution temporary threshold shift (IRTTS). A physical stress to 100 W—which exceeded the endurance level when demanded simultaneously to the noise exposure—did not show any favorable effects. However, if the same physical stress succeeded the noise exposure, and when it was interrupted several times for the audiometric measurements, it also brought about significant accelerations of the restitution processes. Some reductions in physiological costs of the hearing were found due to an intervening alcohol consumption (blood alcohol concentration ～ 0.08%) prior to the noise exposure and a simultaneous physical load of 50 W. Smoking 10 cigarettes instead of the consumption of alcohol was associated with a reduced TTS, but a prolonged restitution time. IRTTS as total physiological costs of the most unfavorable combination of noise, simultaneous high physical workload, and preceding smoke exposure was increased. The results of the test series with cigarette smoke—probably due to the small group of just 8 Ss and the counteracting effects of the agents carbon monoxide (CO) and nicotine—were not statistically significant, but these exposures were associated with a substantial activation of the cardiovascular system. Significant heart rate increases are evidence that CO and nicotine must not be neglected as influential factors in the context of physiological costs that the organism, and especially the hearing, has to pay for noise exposures. © 2002 Wiley Periodicals, Inc.     

手持式乙醇测试仪的研制

介绍一种新型的乙醇测试仪的设计原理、实用电路及实验结果。该仪器具有体积小、灵敏度高、选择性好、稳定性高、响应时间短、手持、能方便地现场实时地检测气体中气态酒精浓度等特点。可用于交通安检及酒厂、食品工厂发酵的监测。     

Effects of alcohol and caffeine on maritime navigational skills

Twelve experienced navigators participated in an experiment to determine the effects of alcohol, caffeine, and an alcohol+caffeine mixture on performance during the following tasks: visual search, the search and location of items on a navigational chart (chartsearch) and the solving of maritime navigational problems. Alcohol (75 ml) produced impairment in performance on visual search (p<0.05) and navigational problem-solving (p<0.01). Caffeine was found to enhance performance on visual search (p<0.05) but not on the chartsearch, although a significant correlation was found between performance on the two tests (p<0.05). Caffeine was not found to improve the accuracy of navigational problem-solving (p>0.05). Neither alcohol nor caffeine had any significant effect on the speed of problem-solving (p>0.05).     

Night-time driving: the use of seat-belts and alcohol

Abstract

The objective risks of accident involvement associated with night driving, seat-belt use and alcohol intoxication have been reported from many countries. However, much less is known about the risks associated with combinations of these activities, even though these are common. A brief review of the relevant literature suggests that young drivers and drinking drivers are less likely to wear seat-belts at night. The results of a night-time survey in the Netherlands support this finding, with the lowest rate of belt use, 21%, being for young drivers with blood alcohol levels in excess of the legal limit (0·50%). Thus those drivers who are most likely to become involved in a crash are least likely to protect themselves from injury. The implications of these findings for accident countermeasures are briefly outlined.     

The effects of toluene and alcohol on psychomotor performance

Abstract

Eight male subjects took part in four experimental sessions in an exposure chamber to assess the effects of toluene (80 p.p.m.) and alcohol (0.4 ml per kg body weight) individually and in combination on four measures of performance and also on mood. Alcohol caused a significant deterioration over the exposure session in performance on pursuit tracking and visual search tasks and also in mood. Toluene had no significant effect on any of the behavioural measures, but examination of mean scores for each treatment suggested a tendency for performance and mood to deteriorate more when alcohol and toluene were administered together than when alcohol was taken alone.     

Effects of alcohol and caffeine on maritime navigational skills

Twelve experienced navigators participated in an experiment to determine the effects of alcohol, caffeine, and an alcohol + caffeine mixture on performance during the following tasks: visual search, the search and location of items on a navigational chart (chartsearch) and the solving of maritime navigational problems. Alcohol (75 ml) produced impairment in performance on visual search (p&lt; 0.05) and navigational problem-solving (p< 0.01). Caffeine was found to enhance performance on visual search (p< 0.05) but not on the chartsearch, although a significant correlation was found between performance on the two tests (p< 0.05). Caffeine was not found to improve the accuracy of navigational problem-solving (p> 0.05). Neither alcohol nor caffeine had any significant effect on the speed of problem-solving (p> 0.05).