基于迭代的拟二元逐板计算多组分精馏的简捷设计法

在精馏设计过程中,简捷法是对所提供的方案进行快速估算的先决条件.本文提出将多组分体系转化为拟二元体系的观点,将多组分体系的设计问题转化为拟二元的简捷设计问题.设计过程分为两层循环,内层完成精馏过程的严格模拟,外层进行迭代的拟二元设计.文中引用两个实例,设计结果表明,该方法既可用于理想物系,又可用于非理想物系.     

二元物系双塔蒸馏的静态模型研究

本文以非理想二元物系双塔蒸馏为研究对象,依据物量、热量守恒原理及“无损”近似原则,采用Wilson方程与汽液平衡方程相结合的热力学方法,建立了该过程的静态数学模型,并对过程的静态特性进行了数字仿真。仿真结果表明,该模型揭示了二元物系双塔蒸馏的有关规律,可用于指导该系统的工艺设计、过程及操作优化。     

气相色谱法测定公共场所室内空气中苯系物

苯系物对人体及环境具有较强的危害性,其浓度的测定是大气环境监测的一项重要内容。本文对气相色谱法测定公共场所室内空气中的苯系物进行了介绍,该方法操作简单、结果准确,可用于公共场所室内空气中苯系物的测定。     

吹扫捕集-气质联用测定水中苯系物

以吹扫捕集方式,通过GC/MS测定水中苯系物。考察了吹扫时间、吹扫流量、解析时间、解析温度对回收率的影响,确定了测定水中苯系物最佳实验条件。方法平均回收率96%～102%,检出限为0.03～0.39μg/L,本方法可用于水中痕量苯系物测定。     

分段函数法逐板计算非理想物系的理论板数

运用分段函数法可以逐板计算非理想物系的理论板数:首先对该非理想物系的气液平衡数据进行分段拟合,得到气液相组成之间的分段函数;然后利用逐板计算法求解非理想物系的理论板数。利用AspenPlus中塔的Radfrac模块进行严格计算和验证,结果显示,采用分段函数法逐板计算的理论板数为11.72,严格计算法得到的理论板数为11,两者非常接近。因此,采用分段函数法逐板计算非理想物系的理论板数是一种正确而有效的方法。     

不可逆热力学分离过程理论

将热力学原理和理论扩展到不可逆过程 ,形成不可逆热力学理论 ,并应用于扩散传质分离过程 ,建立不可逆热力学分离过程理论 ,其核心为描述多组分物系组分间相对运动的普遍化麦克斯韦尔 -斯蒂芬方程。该理论可合理地解释一些传质“奇异”现象 ,计算非理想物系传质扩散系数 ,预测多组分分离过程的传质速率和级效率 ,其模拟计算结果与实验测定值能很好地吻合。不考虑组分间的交互作用 ,视各组分效率相等的模型计算结果与实验测定值存在偏差 ,物系的非理想程度越大 ,偏差越大。     

基于混合模型法的精馏塔热耦合技术研究

针对非理想物系,提出了基于混合模型法的精馏塔热耦合参数优化方法,充分结合了Aspen软件对过程的准确模拟和神经元网络简洁计算的优点,首先获得参数寻优的可行域,然后利用遗传算法对目标函数进行全局寻优.将优化后的热耦合技术应用于中国石油吉林分公司脱乙烷塔与乙烯精馏塔,可节省能耗22.9%.该方法还可用于相关工业过程热耦合技术中.     

同伦函数法用于非理想物系分离的计算

在多组分非理想物系分离计算中，考查了牛顿同伦法、热力学同伦法，莫弗里板效率为参数的参数连续法。实例计算表明同伦函数法是一种对初值要求不高，对各种非理想物系分离计算效果较好的一种算法。     

用联合算法模拟复杂精馏过程

提出一个复杂精馏过程的通用数学模型,并采用改进的松弛法与修正的N-R法相结合的联合算法求解该模型。通过对理想物系、非理想物系和Petlyuk塔精馏过程的模拟计算,证明该算法通用性强、可靠性高、收敛速度快,模拟结果与文献及工业实验吻合很好。     

基于MATLAB的精馏设计型计算

精馏设计型计算具有计算量大、算法复杂等特点。利用Matlab平台，开发了双组分精馏设计型计算程序。应用结果表明，此程序具有一定的通用性，可应用于部分双组分理想物系。     

A mass and energy balance stage model for cyclic distillation

Cyclic distillation is an emerging process intensification technology, which can improve separation efficiency compared to conventional distillation. As most current models only account for the mass transfer, there is a lack of a stage model for cyclic distillation processes, which includes considerations of both mass and energy transfer. Such a model is presented in this article, and using this model, selected case studies, describing binary and multiple component systems with both ideal and nonideal liquid phases, are investigated. The presented stage model allows for the modeling of both mass and energy transfer for a cyclic distillation process and allows for multiple feed locations, as well as side draws. With the energy balances included, the dynamic vapor flow rate can be described. This was shown to have a significant effect on the separation, especially for cases where the change in the vapor flow over the column height was high.     

Competitive Biosorption of Acid Dyes from Binary Solutions onto Enteromorpha prolifera: Application of the First Order Derivative Spectrophotometric Analysis Method

The biosorption of Acid Red 274 and Acid Red 337 dyes from single and binary solutions on Enteromorpha prolifera was investigated in a single stage batch system. The first order derivative spectrophotometry was tested in order to analyse the studied binary solutions of the selected dyes. The single- and multi-component Langmuir and Freundlich isotherm models were applied to the experimental equilibrium data and the isotherm parameters were estimated. It was observed that the uptake amounts of the first component decreased with increasing concentration of the second component from binary solution. As a result, the binary biosorption of AR274 and AR337 dyes on E.prolifera have an antagonistic effect. The binary biosorption of AR274 and AR337 dyes in a single stage batch system was modelled and the equilibrium concentrations of the exit stream were found by using the experimental equilibrium curves and operating lines for the biosorption of single and binary dye solutions.     

Bulk synthesis and crystal structure of the first stage europium-graphite intercalation compound

A first stage binary graphite intercalation compound was synthesised in the lithium-europium-graphite system by direct immersion of a pyrolytic graphite platelet in a molten lithium-based alloy with a well chosen Li/Eu ratio at 350 °C. The as-obtained bulk EuC₆ compound exhibits mono-layered intercalated sheets of europium surrounded by two graphene sheets with a repeat distance equal to 487 pm. The three dimensional study of the EuC₆ crystal structure shows a hexagonal symmetry for this compound that crystallises in a P6₃/mmc space group with the following unit cell parameters: a = 430 pm and c = 974 pm.     

乙酸异丙酯-异丙醇-DMSO的等压汽液相平衡和萃取精馏模拟

在101.3 kPa压力下,采用汽液平衡釜测定了二元物系异丙醇+二甲基亚砜（DMSO）、乙酸异丙酯+DMSO和三元物系异丙醇+乙酸异丙酯+DMSO的汽液平衡数据。利用Van Ness点校验法检验以上气液平衡数据,结果表明,数据符合热力学一致性。采用NRTL、Wilson和UNIQUAC活度系数模型对二元数据进行了拟合,并进行了三元物系汽液相平衡数据预测,结果表明,回归数据和实验数据吻合良好。Wilson模型的预测结果优于NRTL和UNIQUAC模型。一定量DMSO的加入可消除异丙醇和乙酸异丙酯的共沸点,因此,DMSO可作为一种有效的萃取剂来萃取精馏分离此二元物系。然后,通过流程模拟软件Aspen Plus,使用获得的二元交互作用参数对三元系统的萃取精馏进行了模拟。讨论了在不同的操作条件（塔板数、进料位置、溶剂比和回流比）下,异丙醇和乙酸异丙酯分离的情况,得到了最适宜的操作条件。     

酯化釜塔顶温度控制系统改造

介绍了串级控制在仪化研究院半连续聚酯试验装置酯化釜塔顶温度控制上的应用,解决了酯化釜塔顶温度调节滞后问题,提高了调节过程的品质     

基于EXCEL的二元非均相恒沸精馏逐板计算

本文介绍了运用EXCEL逐板计算二元非均相恒沸精馏所需要的理论板数,同时获得各板温度以及汽液组成的方法。此法充分利用了EXCEL强大的函数功能和单变量求解功能完成了计算过程而无需编程,因此具有简单、快速、准确的特点。     

Determination of concentration changes on membrane surface as function of time during evaporation of reverse-osmosis film casting solutions

Data on the activity of acetone for the binary system acetone-formamide, and a specific ternary system cellulose acetate-acetone-formamide are given for the temperature range 0 to 30°C. A method of determining concentration changes occurring on the membrane surface during the evaporation stage in the process of making cellulose acetate reverse osmosis membranes is illustrated.     

Simultaneous degradation of atrazine and simazine by a binary culture of Stenotrophomonas maltophilia and Arthrobacter sp. in a two‐stage biofilm reactor

BACKGROUND: The impact of mixtures of chloro‐triazinic herbicides, such as atrazine and simazine, on aquatic ecosystems is of environmental concern. To study their biodegradation under various operational conditions, a binary community comprising Stenotrophomonas maltophilia and Arthrobacter sp. attached to the porous support of a packed bed reactor, was evaluated. RESULTS: The genetic analysis of the two atrazine‐degrading strains revealed that genes atzA, atzB, atzC are present in both bacteria, but only S. maltophilia possess atzD. Thus, by cultivating Arthrobacter sp. on these herbicides, cyanuric acid accumulation was observed. When the binary community was cultivated in the biofilm reactor, at all the loading rates probed, both herbicides were entirely removed. However, complete biodegradation of cyanuric acid was not achieved. CONCLUSIONS: Even with a two‐stage reactor, cyanuric acid was only partially removed. This fact could be attributed to the absence, in the second stage, of an easily degradable energy source, required by S. maltophilia for the uptake and cometabolic degradation of the recalcitrant heterocyclic ring. Responding to differences in nutritional conditions prevailing at each reactor stage, local differences in species' predominance were clearly detected by microbiological and molecular biology methods. Copyright © 2010 Society of Chemical Industry     

蓄热型热泵热水器单级与复叠循环性能比较

引言 热泵机组的复叠循环,可以降低在寒冷气候下压缩机的压缩比,提高其制热效率[1].Agyenim等[2]采用石蜡为相变蓄热材料(PCM),分析了空气源热泵热水器内部传热特性,由于石蜡的热导率较小导致蓄热放热效率较低,PCM和水之间换热效率只有52%,为此开发了一种新型套管式换热器用于加强PCM和水之间的换热.Long等[3]数值模拟和实验分析了相变蓄热水箱的蓄热放热过程,在室外于湿球温度24/20℃,进水温度24℃条件下,热泵系统平均COP为3.08.陈光明等[4-5]设计一种新型的复叠式空气源热泵装置,提出单级向复叠运行转换足由两者运行时的吸、放热量、耗功量和运行性能系数决定,同时还与压缩机的形式有关,输气系数、绝热效率随压缩比变化越小,复叠运行优势越小.吴青吴等[6]以常规工质对复叠式热泵热水器在不同运行工况下的循环特性进行了理论计算,提出冬季运行复叠式循环,夏季单独运行高温级循环,有利于系统的节能.     

Some results on estimation for two—stage clinical trials

A clinical trial setting is considered in which two treatments are available for a particular ailment. A two—stage trial is studied, in which patients are randomised equally in the first stage, and the better treatment at the end of this stage is used exclusively in the second stage. For exponential and Bernoulli responses, the exact bias and variance of the estimated treatment difference at the end of the trial are derived. Corresponding results for normal responses with unequal variances are also obtained, and the numerical accuracy of a normal approximation is investigated. The results indicate that the bias in estimation can be up to 25% when the size of the first stage is small, reducing to less than 7% for moderate first—stage sizes. For both exponential and Bernoulli responses, a normal approximation works well for moderate first—stage sizes, with the approximation for Bernoulli responses being slightly better.