Membrane materials in the pervaporation separation of aromatic/aliphatic hydrocarbon mixtures—A review

The separation of aromatic/aliphatic hydrocarbon mixtures is a significant process in chemical industry, but challenged in some cases. Compared with conventional separation technologies, pervaporation is quite promising in terms of its economical, energy-saving, and eco-friendly advantages. However, this technique has not been used in industry for separating aromatic/aliphatic mixtures yet. One of the main reasons is that the separation performance of existed pervaporation membranes is unsatisfactory. Membrane material is an important factor that affects the separation performance. This review provides an overview on the advances in studying membrane materials for the pervaporation separation of aromatic/aliphatic mixtures over the past decade. Explored pristine polymers and their hybrid materials(as hybrid membranes) are summarized to highlight their nature and separation performance. We anticipate that this review could provide some guidance in the development of new materials for the aromatic/aliphatic pervaporation separation.

A 2D numerical study on the condensation characteristics of three non-azeotropic binary hydrocarbon vapor mixtures on a vertical plate

To improve the transportation efficiency and reduce the supply cost,the liquefaction becomes an important technology to store and transport the natural gas.During the liquefaction,the various components(e.g.propane,ethane,methane etc.)undergo fractional condensation phenomenon due to their different boiling points.This means that when one component condenses,others play a role of non-condensable gas(NCG).In order to reveal the influence mechanism of NCG on this condensation process,a numerical method was employed in this paper to study the condensation characteristics of three non-azeotropic binary hydrocarbon vapor mixtures,namely the propane/methane(80%–95%),ethane/methane(65%–85%)and methane/nitrogen(2%–13%)mixtures,on a vertical plate.The model was proposed based on the diffusion layer model,and the finite volume method was used to solve the governing equations.A user defined function was developed by cell iterative method to obtain the source terms in the condensation process.The numerical results show that the gas phase boundary layer formed by the NCG becomes the main resistance to the reduction of heat transfer coefficient.And for the above three mixtures,there is a negative correlation between the NCG concentration and the heat transfer coefficient.Meanwhile,the results show a good agreement with the experimental data,meaning that the proposed model is reliable.Three mixtures within same non-condensable mole fraction of 20%were also investigated,indicating that the mixtures with a higher binary hydrocarbon molecular ratio have a lower heat transfer coefficient.As a result,the presence of the lighter NCG contributes to a thicker boundary layer.

Vapor-Liquid Equilibrium of Toluene-Polycyclic Aromatic Hydrocarbon System in Sub- and Supercritical State

The phase behaviors of toluene/polycyclic aromatic hydrocarbon mixture systems were investigated with a continuous-flow type apparatus at 573.2, 598.2, 623.2 and 648.2 K, while the pressure changed from 1 to 5MPa. The pseudo-binary phase behaviors were predicted with the Peng-Robinson equation of state with interaction parameters between toluene and pseudo-components considered. The phase diagrams of the system have been classified following the category of phase boundary diagram models. The extraction selectivity and efficiency of tolu-ene as a solvent was discussed by comparing with that of hexane. The prediction model for selectivity was also suggested.

双元碳氢混合制冷剂在饮料柜制冷系统中的应用研究

基加利修正案促使我国推进HFCs类制冷剂的削减和节能政策,其中碳氢混合制冷剂是近年间新兴的解决方案。本文以饮料柜为应用对象,建立了物理数学模型,通过仿真模拟和实验测试的方式,研究了双元碳氢混合制冷剂在饮料柜制冷系统中的可能性。结果表明,相比R290制冷剂,R600a/R290混合制冷剂性能更优,排气压力下降了24%,吸气压力下降了42%,耗电量下降了7.8%,噪音下降了5.6dB(A),可以作为新一代的饮料柜用制冷剂。

基于沸石分子筛的无机膜渗透蒸发和气体分离技术进展

相较于传统分离技术,膜分离技术具有分离效率高、能耗低、便于与其他技术集成等优点。与有机分离膜相比,无机膜具有稳定性高、机械强度大、分离效率高、耐微生物侵蚀等优势。针对基于沸石分子筛的无机膜分离技术,介绍了当前常用分子筛膜的种类;探讨了分子筛膜的主要制备方法;详细阐述了分子筛膜在渗透蒸发以及气体分离领域中的应用进展,如氢气回收、天然气净化、二氧化碳捕集和烃混合物分离。对当前存在的问题进行了分析并对今后的发展进行了展望,强调了在降低制造成本、提升分子筛膜制备技术、应对多组分分离挑战等方面的研究重点。

纯氢/混氢碳氢燃料喷嘴技术综述

在民用飞机日益普及的时代,大气中飞机尾气排放对环境的污染问题日益凸显,发动机碳排放需要进一步降低,而氢能的使用为实现零碳排放提供了可能。介绍了氢气与不同碳氢燃料特性,阐述了氢作为航空发动机和燃气轮机燃料的优势,以及纯氢/混氢燃料在主燃烧室设计中带来的诸多挑战。基于氢气及航空煤油等碳氢燃料的基础特性,以纯氢气及以混氢燃料喷嘴技术为研究对象,总结和讨论了氢燃料在航空发动机、燃气轮机中的应用及喷嘴设计技术。同时,考虑氢燃料的加入对燃烧稳定、排放和火焰传播速度的影响,阐述了氢燃料喷嘴发展的关键技术,包括氢燃烧组织及喷嘴设计、低NOX排放氢燃烧、氢燃烧防回火和氢燃烧不稳定抑制等技术,为氢燃料航空发动机燃烧室喷嘴设计提供了新思路。

Comparative Analysis of Some Representative Models of Viscosity Versus Pressure in the Case of Various Hydrocarbons and Their Mixtures

A critical study of some representative models has been conducted with the experimental determinations of the viscosity of ten pure substances and three binary systems measured as a function of temperature T(25℃,40℃,60℃,80℃,90℃)and pressure P(≤ 100 MPa). The pure substances were:toluene,p-xylene,m-xylene,o-xylene,methylcyclohexane, methylnaphtalene,decahydronaphtalene,phenyldodecane,heptamethylnonane and tetramethylpentadecane(pristane).The three binaries were:toluene+ tetramethylpentadecane,toluene+ methylnaphtalene and toluene+ heptamethylnonane,for molar fractions x of toluene ranging between 0 and 1.The three binaries are highly'contrasted' systems,i.e.systems in which the viscosities of the pure components are very different for each P,T pair.In all,547 experimental determinations were carried out,the 279 experimental data for viscosity of the pure substances and 268 data concerning the mixtures(x ≠0 and 1) were used to make a critical analysis of the various representative models,These included an empirical representation of variations of versus T on each isobar,a self-referencing model developed in our laboratory,a corresponding states model with one reference,various mixing rules with or without adjustable parameters,a combination of the self-referencing model and mixing rules,a method based on the Bloomfield and Dewan excess viscosity,and a group contribution method,comparison of the results showed the self-referencing method to be of particular interest,Moreover when coupled with mixing rules without adjustable parameters it was able to account satisfactorily for the variationsη(P,T,x) of the mixtures,on the simple basis of knowledge if the viscosity of the components of the system,at 25℃ and at atmospheric pressure,For all the binaries an average absolute deviation of 9.5% was observed.Finally it appears that the introduction of the pressure parameter does not alter the usual performance of each of the models tested,although they were not al equivalent as regard their performances.

Group Contribution based Flammability Limit Estimation of Hydrocarbon-Inert Gas Mixture

As group contribution method is easy to apply and has a wide application range,current study has developed this model to predict flammability limit of hydrocarbons mixed with inert gas using the Marrero/Gani group contribution method,which is significative to the safe application of hydrocarbons in the ORC system.The whole modeling process is divided into two parts:pure compound prediction and mixture prediction.The contribution factors of inert gases and dilute concentration were first introduced in the group contribution method.Moreover,the respective 95%-confidence interval of the mixture based on linear superposition method has been proposed in the developed group contribution model to improve the safety coefficient.For CO2 as inert gas,the average relative error and correlation coefficient are 5.34%and 0.88 for lower flammability limit while 6.99%and 0.95 for upper flammability limit.For N2 as inert gas,the average relative error and correlation coefficient are 7.47%and 0.84 for lower flammability limit while 6.68%and 0.97 for upper flammability limit.Most importantly,this group contribution method has extended the application range to make up the shortcomings of other flammability limit prediction methods aiming at hydrocarbon and inert gas mixtures and proposed the uncertainty analysis to provide reliable prediction range.

Strong synergistic effect of cationic hydrocarbon surfactant and novel nonionic tri-block short-chain fluorocarbon surfactant mixtures on surface activity, wettability and solubilization

Mixing hydrocarbon surfactants with fluorocarbon surfactants is still an important strategy to improve the economic benefits and performances of fluorocarbon surfactants and expand their range of application.Herein,we prepared a novel kind of hydrocarbon-fluorocarbon surfactant mixtures via mixing a cationic surfactant,cetyltrimethylammonium bromide(CTAB),with a tri-block nonionic short-chain fluorocarbon surfactant(F_(9)EG_(13)F_(9))in aqueous solution.The results showed that adding a small CTAB amount to F_(9)EG_(13)F_(9)(the molar fraction of CTAB in the mixture(x_(1))was 0.2)could greatly reduce its critical micelle concentrations(cmc)from 0.408mmol/L to 0.191 mmol/L.At this x_(1),the contact angle of the mixture was the minimum(57.7°)at 100 s on polytetrafluoroethylene film,which was even lower than that of F_(9)EG_(13)F_(9).Besides,CTAB/F_(9)EG_(13)F_(9) mixtures possessed better colloidal stability and solubilization ability toward hydrophobic dye(SudanІ)than F_(9)EG_(13)F_(9).The outstanding performances of binary surfactant mixtures benefited from the non-ideal mixing and strong synergistic effect evidence that CTAB/F_(9)EG_(13)F_(9) surfactant mixtures could be used in practical applications instead of individual F_(9)EG_(13)F_(9),thereby reducing the used cost of F_(9)EG_(13)F_(9).

渗透汽化分离芳烃/烷烃混合体系的研究进展

本文对近年来应用于分离芳香烃 /烷烃混合体系的渗透汽化 (简称 PV)膜材料 ,特别是高分子材料进行了较为系统的综述 ,并简要概述了渗透汽化膜分离特点。

烃类气体在多孔介质中的吸附研究

气藏烃类流体储存于地下的多孔介质中 ,部分烃类气体会吸附在多孔介质固体表面 ,从而会应影响气藏储量计算、气井产能计算、气藏开发动态分析等气藏工程计算的准确性。文章分析、研究了烃类气体在储层多孔介质表面上的吸附机理 ,应用F—HVSM模型 ,通过实例计算 ,得到了烃类气体混合物在储层多孔介质表面的吸附情况。研究表明 :烃类气体混合物在储层孔隙介质中的吸附量随温度的升高而减少 ,随压力的升高而增大 ;在同一孔隙介质中 ,当温度、压力相同时 ,重组分含量相对较高的烃类气体体系 ,其吸附量相应较大 ;对同一烃类气体体系而言 ,在相同的温度、压力下 ,孔隙介质渗透率越低 ,比表面越大 ,其吸附量也越大 ;烃类气体混合物在中、低渗储层多孔介质表面的吸附量的数量级为 10 -2 mol/kg。

热泵系统用R744/HCs混合工质配比范围研究

针对现有碳氢类(HCs)工质进行综合分析比较,选定了一些适用于热泵系统的R744/HCs非共沸混合工质对。通过对选定的混合工质临界参数和温度滑移特性的进一步计算分析,确定了其适用的热泵循环,并建立了快速确定亚临界循环热泵系统用R744/HCs非共沸混合工质中R744质量配比范围的计算程序。结合热泵热水器的工况及高压侧压力的要求,利用计算程序确定了R744/R600、R744/R600a、R744/R601和R744/R601a的质量配比范围。

分隔壁精馏塔分离芳烃混合物的研究

利用分隔壁精馏塔实验室小试装置对苯、甲苯、二甲苯三组分芳烃混合物的分离进行了初步探索,考察了进料组成、进料速度、回流比、分配比等因素对分离效果的影响。结果表明,当分隔壁精馏塔进料中甲苯的体积分数为60%、苯和二甲苯的含量相当、进料速度为1.1mL/min、分配比为1:2、回流比为6:1时,分离效果最佳,此时塔顶采出苯的质量分数达到94.9%,侧线采出甲苯的质量分数为96.4%,塔釜中不含轻组分。

SINOALKY硫酸法烷基化工艺技术及其工业应用

SINOALKY硫酸法烷基化技术采用N型多级多段静态混合反应器和自汽化酸烃分离器集成,反应原料采用多点进料方式,采用高效酸烃聚结材料进行反应流出物中的酸烃分离。在中国石化石家庄炼化分公司进行了工业应用,在满负荷条件下,烷基化油RON为96.5～97.0,酸耗为58.9 kg/t。该技术具有工艺流程简单、反应器易维护、低酸耗、产品质量好的特点。

碳氢化合物混合工质在制冷系统中的应用研究

本文阐述了一种碳氢化合物的混合物作为制冷剂的可行性。阐明了这种物质在冰箱应用中的安全性和成份含量变化的影响,通过热力学性质和实验表明TR12是一种热力学性质与R12极为相似、制冷效果和节能效果都优于R12的制冷制。

柴油机燃烧多环芳香烃前驱体等物质的化学动力学研究

为了揭示混合气浓度对柴油机排放的影响规律,采用正庚烷氧化详细反应机理及化学动力学分析软件对不同燃空当量比下柴油机燃烧初级碳烟粒子前驱体等重要反应中间产物或自由基的形成及发展历程进行了数值模拟.模拟结果表明,降低混合气浓度可以实现低温燃烧,使燃烧温度远离“碳烟形成温度窗”,大幅度降低柴油机碳烟排放.混合气浓度对反应中间产物或自由基有重要影响,通过改变混合气浓度可以控制燃烧过程中多环芳香烃(PAH)前体物乙炔(C2H2 )、炔丙基(C3H3 )及其他重要物质羟基(OH)、过氧羟自由基 (HO2 )、过氧化氢 (H2O2 )、甲醛(CH2O)和一氧化碳(CO)等的生成量,从而实现控制柴油机排放.

胶束增敏导数-恒能量同步荧光法同时测定多环芳烃混合物

本文建立了多环芳烃的胶束增敏导数 -恒能量同步荧光同时分析方法。恒能量同步扫描所得到多环芳烃的谱带位置均对应常规光谱中的最佳激发 -发射位置 ,经二阶求导后 ,消除谱带的干扰 ,所得的二阶导数 -恒能量同步荧光光谱即可用于同时测定艹屈 、荧蒽、菲等三种多环芳烃。该法快速、灵敏 ,为预测和治理水污染提供一种快速简便的测试手段。

石油化工用换热器传热计算之一——烃类及其混合物密度的确定

石油化工用换热器传热计算大量涉及烃类及其混合物物性数据的计算。使用的参数,可供选择的计算公式广泛而且繁杂,如何正确地进行烃类及其混合物的密度计算,是传热计算中的基本问题。尤其在其它物性(如粘度、导热系数、炝、熵等)计算公式中,涉及到密度的情况下,能否正确确定密度值,就成为传热计算的关健。本文论述了烃类及其混合物密度计算的方法、程序,并对不同方法计算结果进行了比较。

碳氢化合物在冷冻箱系统中的试验研究

通过对同一台冷冻箱的不同制冷剂循环系统的反复测试 ,从制冷循环的多个参量分析中给出了替代制冷剂R6 0 0a/R2 90的实际循环效果 ,非共沸混合制冷剂作为中小型制冷装置中的直接替代物 ,能够满足原系统的温度、压力要求 ,其充注量仅为R12的 35 %～ 4 0 %。

大气漂尘中苯并[a]芘的简单同步荧光测定

通过选择合适的能量差(Δ-υ=1 400 cm-1),建立了大气漂尘中苯并[a]芘的恒能量同步荧光分析法。苯并[a]芘在甲醇与十二烷基磺酸钠(SDS)溶液中均有良好的线性关系(R>0.999),检出限分别达到1.34 nmol/L与0.40 nmol/L。该法亦可应用于18种多环芳烃混合物中苯并[a]芘的鉴别。