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1.
渗透汽化过程中膜的溶胀行为研究   总被引:4,自引:0,他引:4       下载免费PDF全文
任吉中  江成璋 《化工学报》1998,49(4):400-408
以壳聚糖和硫酸交联壳聚糖膜为研究对象,详细考察了两种膜在乙醇──水体系中的溶胀特性.实验发现,在溶胀过程中存在强烈的耦合效应.为了分析溶胀过程中的耦合效应,定义了组分在膜中的活度与体积分率的关系,同时,建立了溶胀过程参考态的概念,用以描述单个组分与膜之间相互作用对活度系数的贡献.在溶胀过程中,组分的活度系数相对于参考态活度系数的差异反映了膜内组分间耦合效应的影响.水的溶胀特性基本受控于水与膜之间的相互作用关系,对于乙醇而言,其溶胀特性强烈地受水在膜中溶胀特性的影响.  相似文献   

2.
纤维增强聚合物(FRP)具有突出的耐腐蚀、高强度、非磁性、质量轻、高疲劳限值的特性,而光纤布拉格光栅(FBG)具有抗电磁干扰、尺寸小、准分布式测量、抗腐蚀、绝对测量等突出优点.将FRP与FBG相结合,制作FRP~FBG智能复合筋.通过材料拉伸和温度试验分析智能复合筋的力学特性、应变传感特性和温度传感特性.试验结果表明:FRP—FBG智能复合筋既不改变FRP的力学特性也不改变FBG的应变传感特性,智能复合筋的温度传感性系数提高了约2.16倍.FRP—FBG智能复合筋克服了FBG在混凝土中埋设时难以保护的难题,是集功能材料和结构材料于一体的新型土木工程材料,具有广泛的应用前景.  相似文献   

3.
对用酸性气体脱除物做成的样品STW的硫化特性等性能进行了研究。结果表明,该物质对NR有较好的硫化特性和一定的软化增塑作用;STW用量3.0份以上时硫化特性较好,但炼胶时粘辊.硫化胶有喷霜现象。STW与促进剂M并用时,硫化特性与促进剂D相似.胶料有较好的物理机械性能。STW已在船用橡胶护舷中应用,收到较好经济效益和社会效益。  相似文献   

4.
莫力瑛  金在琴 《橡胶工业》1996,43(10):600-601
研究了新型橡胶活化剂M和DM用于轮胎胎体胶料配方中时对混炼胶硫化特性和硫化胶物理机械性能的影响。试验结果表明.用活化剂M和DM部分替代促进剂DM时,混炼胶硫化特性基本保持不变,对加工性能无明显影响.而硫化脏物理机械性能也相差不大。在轮胎胶料中采用这两种新型活化剂具有显著的经济效益。  相似文献   

5.
本文介绍了利用热缩材科的热收缩特性在碳纤维复合材料(CFRP)管成型中用于提高产品表面质量的工艺技术。分析了热缩塑料的应用特性及要求.研究了热缩工艺.有效地解决了复合材料管材的表面质量问题。  相似文献   

6.
煤特性研究   总被引:5,自引:2,他引:5  
煤的许多特性是研究煤的洁净燃烧和利用的基础,对这些特性的深入研究有利于加强和提高煤的洁净利用.就近年来国内外对煤的特性研究的最新成果进行了综述,介绍了煤特性的研究方法、煤质程度、煤岩结构等因素对煤的燃烧特性、成型特性、粘结特性、电特性以及热特性的影响.  相似文献   

7.
在实验室水平管式电炉上, 在较低温升速率和低温燃烧 (300℃~550℃) 的条件下分别对合山高硫烟煤和晋城烟煤的四种不同粒度煤样的燃料NOx 和有机硫分SO2 的生成特性进行了研究,并且得到了在当前试验条件下颗粒粒度与燃料NOx 和有机硫分SO2 生成特性的定性关系及结论. 还研究了以CO为主的还原气氛在煤燃烧过程中对固氮和固硫所产生的影响以及煤粉超细化燃烧方式下NOx 和SO2 的生成特性.  相似文献   

8.
含湿多孔介质的干燥特性   总被引:2,自引:0,他引:2  
基于含湿多孔介质的水分蒸发过程及其内部毛细管水分的蒸发特性,分析了含湿多孔介质在干燥过程中发生体积收缩的原因.讨论了多孔介质的物性和外部干燥条件对其体积收缩特性的影响。  相似文献   

9.
本文对不同预还原度的铁矿球团在铁碳熔体中熔融还原的规律进行了实验和理论研究.针时熔融还原反应特点,提出了表观FeO浓度概念.根据传质理论和球团矿熔融还原的特性,建立了反映球团矿在铁碳熔体中熔融还原反应规律的双相传质模型.实验和理论计算结果表明,球团预还原度和熔化速率等因素对熔融速率影响较大.  相似文献   

10.
江波  张志莲 《现代塑料》2005,(10):20-24
复合共挤出片材使多层具有不同特性的物料在挤出过程中彼此复合在一起,使制品兼有几种不同材料的优良特性,在特性上进行互补.从而得到特殊要求的性能和外观,如防氧和防湿的阻隔能力,着色性、保温性.热成型和热粘合能力及强度、刚度、硬度等机械性能。[编者按]  相似文献   

11.
Conclusions A correlation is shown between the high-temperature, physicochemical processes in basic refractories, changes and reactions in the gaseous phase, and the nature of the wear of the roof of a tunnel kiln.As a result of dissociation, oxidation, and volatilization the waste gases are enriched with vapors of alkalis, CrO3, sulfur trioxide, and oxides of iron and magnesium, and become corrosive with respect to the kiln lining. The reaction of the oxides vapors with each other and with the lining of the roof and their condensation determines the nature of the wear in the magnesite-chromite refractories, the chemical and mineral compositions of the resulting deposits and crusts. The main source of alkalis and sulfur trioxide is the sulfite yeast dregs (sulfite lye) present in the goods being fired.We determined the temperature relationship with the composition and amounts of deposits and crusts. Carcase and skeletal deposits and crusts formed on the firing section of the kiln, mainly periclase and spinel compositions; in the warming-up section the deposits were brittle, granulated, consisting of sulfates, chromates, chromium oxide, periclase, and spinels.It was found that the deposits on the walls of the pores in the MKhS refractories consist of sulfates and chromates, forming solid solutions.Translated from Ogneupory, No. 5, pp. 13–16, May, 1980.  相似文献   

12.
气体燃料具有易于点火、燃烧迅速、燃烧完全等特点,且氮、硫、灰分低,因此燃烧后产生的污染物相对较少,属于较清洁的燃料,且国家燃气补贴政策的实施,使气体燃料燃烧近年来有很好的发展前景。但随着国家对大气污染物的控制更加严格,控制气体燃料燃烧过程中NOx的生成至关重要。笔者介绍了不同种类NOx的产生机理及影响因素,并基于NOx的产生机理提出控制措施,分析目前应用较广泛的燃气燃烧技术的低氮原理及应用现状,最后提出燃气燃烧器应用的展望。燃气燃烧过程中主要以热力型NOx及快速型NOx为主,温度和过量空气系数是影响NOx生成的主要影响因素。燃烧温度高于1 500℃时,热力型NOx呈指数型增长,温度是影响NOx生成的最重要因素。根据NOx产生机理,低NOx燃烧技术的实质是降低最高燃烧温度,控制燃烧区燃料浓度以及氧浓度,缩短烟气在高温区的停留时间,破坏NOx生成的最佳条件,最终抑制NOx的生成。低NOx燃烧技术一定程度降低了NOx的生成,但又会破坏整个燃烧进程,对燃烧和放热过程造成不利影响,降低了燃烧效率和传热效率,因此如何解决这些矛盾是亟需解决的问题。在实际应用中,应根据需求选择合适的燃烧技术,同时可将不同燃烧技术相结合起到稳燃、低氮的效果。应用较广泛的燃气燃烧技术主要是阶段型燃烧技术、烟气再循环燃烧技术、无焰燃烧技术等,其中催化燃烧技术发展前景较好,目前已应用于多个领域,其催化剂的热稳定性和寿命问题是限制其工业上广泛应用的核心问题。  相似文献   

13.
Summary Observation nurseries including 24 varieties of sesame were grown at 23 locations in 16 states. Data for yield, oil and protein content of the seed, and for iodine value of the oil were obtained from certain locations. Sesame seems reasonably well adapted on the better soils of most of the southern one-half of the United States. Average seed yield for varieties at 14 locations was 506 pounds per acre. Average yield of seed, oil, and protein per acre for seven varieties grown at eight locations was 662, 344, and 163 pounds per acre, respectively. The chemical composition of the seed was found to be well within the acceptable range but was markedly influenced both by the varieties and by the locations where they were grown. The average oil and protein contents on a moisture-free basis were 53.53% and 26.25%, respectively. The average iodine value of the oil was 110.0. Average protein content on the moisture- and oil-free basis was 57.28%. The genetic and environmental influences that affect protein content of the seed also inversely affected the oil content. It was suggested that in sesame protein synthesis is favored over oil synthesis as the nitrogen supply to the seed increases. Contribution of the Division of Tobacco, Medicinal, and Special Crops, Bureau of Plant Industry, Soils, and Agricultural Engineering, and the Southern Regional Research Laboratory, Bureau of Agricultural and Industrial Chemistry, U. S. Department of Agriculture. Agronomist, Division of Tobacco, Medicinal, and Special Crops in cooperation with the Department of Agronomy, Texas Agricultural Experiment Station; and chemist, Southern Regional Research Laboratory, New Orleans, La., respectively. The authors wish to acknowledge the assistance of workers in the various state agricultural experiment stations and government agencies who grew the tests and made data and seed samples available.  相似文献   

14.
虫胶在人类生活中无处不在,易附着在直升机、汽车等表面,难以清除,并带来腐蚀等问题,为此研究者开展了相关研究工作,并得到了诸多行之有效的虫胶清理方法,例如有机溶剂法、水基清洗法、激光脉冲法、机械法、生物酶解法以及主动防护与快速清洁相结合等多种方式.针对这些方法的适用范围、清理效果、优缺点等研究现状进行了分析和总结.直升机...  相似文献   

15.
Conclusions The most common and characteristic forms of scrap of magnesia parts differing in form, dimensions, and composition are shown. These include deviations of the dimensions from the nominal, breaking off of the corners and edges, nonuniformity, welding together, spots, voids, fire cracks, spalls, and cracks of different origin.The reasons for formation of scrap were determined. The primary of them are the reduced quality of the raw material (chromite, magnesite) with a larger quantity of impurities containing limited silicon and calcium oxides, sometimes insufficient density, grain size, and completeness of hydration of the magnesite powders, nonconformity of the bunker, proportioning, mixing, and pressing equipment to the requirements of modern production of progressive high-quality refractories, the insufficiently high binding capacity of lignosulfonates, deviations in the quality of assembly and finishing of press equipment and automatic ejectors, of the car floor lining, and in firing conditions, a high variation in density of the green parts, and nonuniform heating and cooling in the volume of the parts and of the whole charge during firing. More than 50% of the total scrap of all forms is due to firing scrap of parts.The primary means of reducing or eliminating scrap of parts and simultaneously increasing their quality based on the reasons for formation of different forms of it were noted. These above all else, are increasing the volumes and improving and introduction of new methods of concentration of magnesite and chromite, a successive increase in the share of chrome concentrates, chromium-containing broken parts, and powders by firing of magnesite and caustic dust in the production of magnesia refractory parts as the result of a decrease in the share of commercial natural chromite and magnesite, the use in the production of parts of high-quality type PMSP-93 powder produced in shaft kilns and used as the charge for production of fused materials, the use of the prospect of processes for production of dense periclase powders uniform in chemical analysis from recovered caustic dust, replacement of obsolete mixing and press equipment by more modern, increasing the strength of green parts by above all else improving the binding properties of LST and increasing pressing pressure, forming of the taper of parts by the side plates of the die, improving the quality of assembly and increasing the reliability of functioning of press equipment and automatic ejectors, improving car floor linings, introduction of new methods and increasing the volumes of production of progressive unfired refractories in place of certain forms of fired parts, observation of all production parameters, and a relationship of the wages of labor to the quantity of scrap and the quality of refractories.Introduction of the new management system and the active work of the quality groups created will open up and lead to the action of unutilized reserves for reduction of scrap.Translated from Ogneupory, No. 2, pp. 31–38, February, 1989.  相似文献   

16.
齐亚兵  贾宏磊 《化工进展》2023,42(1):373-385
熔融结晶技术是利用被分离物质各组分间凝固点的差异,通过控制热量的输入和移出,使被分离组分从熔融液中结晶析出,经洗涤、发汗等操作,实现目标组分分离纯化的一种结晶技术。熔融结晶分离纯化技术由于具有不需要使用溶剂、能耗低、设备体积小、能得到高纯产品等优点,在有机化合物的分离纯化领域得到了广泛应用。本文简述了熔融结晶的方式,介绍了熔融结晶器的类型,综述了熔融结晶技术分离纯化有机同分异构体、有机化工原料、日用品、食品和药品的研究进展,分析了熔融结晶技术分离纯化有机化合物过程中存在的问题,展望了熔融结晶技术分离纯化有机化合物的发展方向。文中指出:随着熔融结晶技术的发展,以提高产品质量,减小能耗和降低成本为目的的耦合熔融结晶技术已成为熔融结晶技术发展的方向。以包含熔融结晶设备、工艺、晶体成核和生长动力学、发汗机理以及传热传质模型的系统工程将会成为熔融结晶分离纯化有机化合物的研究热点。  相似文献   

17.
首先概括介绍了目前国际上存在的几种界面过渡区微观结构的模型,然后分新拌混凝土阶段和水化早期、材料硬化过程中以及材料使用过程中3个阶段描述了界面微观结构的形成以及劣化机理。在第1阶段,界面过渡区形成的可能机理为:边壁效应,絮凝成团作用,微区泌水效应,离子的迁移、沉积与成核生长,水化产物的单边生长效应以及脱水收缩效应。在第2阶段,界面过渡区可能的形成与劣化机理为:自身收缩、化学收缩和自干燥收缩、干缩,集料与浆体膨胀系数的差别,浆体的进一步水化以及水化产物的重结晶。在第3阶段,界面过渡区的形成与劣化机理为:荷载的作用,环境介质的侵蚀,冻融的破坏,碱集料反应以及胶凝材料的进一步水化。同时给出了几种常规的以及可能成为界面过渡区微观结构的表征方法。最后,从原材料的物理、化学组成,配合比以及材料制备工艺角度分析了影响界面过渡区微观结构的因素。  相似文献   

18.
Various aspects of the sonic velocity regime, one of the steady-state regimes of filtration combustion of gases, is analyzed. The conditions and region of existence of the regime, the velocity and structural characteristics of the combustion wave, the gas ignition and combustion mechanisms, conditions for the stabilization of the wave velocity, and regime transitions are considered. A characteristic feature of the regime is the presence of a pressure wave in the zone of turbulent flame due to the choking of channels and narrowings. The main factors determining the nature and properties of the sonic velocity regime are the hydraulic resistance, piezo diffusion, the energetics of the mixture, the compressibility and turbulence of the gas, and the reactivity of the mixture at high pressures and temperatures. The sonic velocity regime is a unique and intriguing combustion regime which is promising for applications.  相似文献   

19.
任瑛  徐骥 《过程工程学报》2018,18(6):1126-1137
蛋白质是生命的物质基础,是生命活动的主要承担者,对蛋白质时空多尺度结构及其控制机制的深入理解是探索生命起源、病理认知及新药开发的基础. 受实验表征手段及时空分辨率的限制,计算机模拟已成为研究蛋白质体系结构及功能的重要手段之一. 由于蛋白质体系模拟所涉及的时间和空间跨度均相当大,因此,准确且快速地描述其时空多尺度结构,从而分析体系的控制机制及相关生理过程,成为分子动力学模拟面临的巨大挑战. 本工作对近半个世纪以来的分子模拟方法,特别是分子动力学方法和相关的增强采样技术在蛋白质体系研究中的应用进行了总结,综述了近年来分子动力学的理论模型和算法的发展,并介绍了这些方法在结构化蛋白质的天然结构与构象变化、固有无序蛋白质的动态结构及其结合底物的动力学过程及分子机理、分子伴侣及病毒等蛋白质复合物体系中的研究成果;汇总了高性能计算的飞速发展所带动的分子动力学模拟软件的变革,拓展了蛋白质模拟的时空尺度,重点阐述了大规模高性能分子动力学模拟在蛋白质研究中的应用;最后,基于介科学理论的飞速发展及其在多种复杂体系的成功运用,对未来蛋白质体系的模拟方法和理论研究的趋势进行了思考和展望.  相似文献   

20.
柠檬酸和谷氨酸N,N-二乙酸优化处理污泥重金属   总被引:2,自引:0,他引:2  
采用柠檬酸(CA)和谷氨酸N,N-二乙酸(GLDA)处理污泥重金属,研究了试剂浓度、pH和反应时间对重金属去除效果的影响,并以重金属去除率为表征,通过正交试验获得CA和GLDA处理重金属的最佳条件。结果表明,增加试剂用量、降低体系pH均有利于重金属的去除,但延长反应时间对重金属的去除效果影响不明显。CA和GLDA处理污泥重金属的最佳条件分别为:CA 0.3 mol·L-1、pH 4、反应时间2 h和GLDA 0.05 mol·L-1、pH 4、反应时间3 h。最佳反应条件下,对于CA和GLDA,重金属Cd、Cu、Pb和Ni的去除率可分别达80.25%、77.75%、64.66%和75.16%,及78.57%、78.48%、64.84%和76.71%。CA和GLDA对重金属的去除效果大小顺序均为:Cd>Cu> Ni>Pb,但GLDA的处理效果优于CA。污泥经CA和GLDA处理后,污泥固相酸溶态重金属含量下降幅度最大,平均达81%,残渣态重金属含量下降52.1%,而污泥液相中重金属含量则增加了17.54倍,说明重金属从污泥固相向液相转移。SEM镜检发现,污泥由处理前表面分散的絮状结构,变成更为明显的团块结构和片层结构,污泥的吸附能力下降,且体积缩小。研究结果表明,CA和GLDA处理污泥能有效降低污泥重金属含量并提高污泥固相重金属的化学稳定性,有利于污泥脱水及脱水后的进一步处理及其资源化。  相似文献   

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