汽液两相流疏水调节器在煅烧炉疏水系统上的应用

介绍汽液两相流疏水调节器的优点及在碱业公司的应用情况。     

汽液两相流自动疏水器在氮肥行业的应用

针对汽轮发电机配套的高低加疏水器时常出现加热器满水威胁机组安全运行,或者无水时蒸汽经疏水器流出,造成蒸汽浪费的现象,将浮子疏水器改成汽液两相流自动疏水器,自动调节容器出口流量,达到节能效果。     

浅析汽液两相流装置在煅烧工序的应用

主要介绍了汽液两相流装置的工作原理,同时提出了汽液两相流装置在纯碱煅烧工序使用过程中,相比于仪表自控阀的优劣势及解决方法。     

垂直上升绝热管内汽液两相流截面含汽率的确定

本文提出在蒸发过程中汽、液两相流的流动机构为泡状流和弹状流。根据汽泡、汽弹在静止液中的上升速度,求得了上升流体中汽泡和汽弹的上升速度。得出泡状流和弹状流截面含汽率的计算式。用γ射线法对蒸发过程中汽、液两相流截面含汽率进行测试,并确定了式中的待定系数。     

关于12 MW生物质发电项目汽轮机岗位开车问题分析及改进措施

针对12 MW生物质(糠醛渣)发电项目汽轮机岗位开车过程中出现的汽封风机频繁跳车、汽封加热器蒸汽侧液位持续性过高及高压加热器疏水管路振动等现象,分析原因是管道中积水过多、多级液封与汽封之间高度差与压差过小、管道支架和管道导淋设置不合理。采用针对性的整改措施后,问题得以解决,保证了汽轮机岗位的成功开车及稳定运行,为整个生物质发电项目实现长周期稳定运行提供有力保障。     

三相循环流化床蒸发器防除垢机理

引　言结垢是蒸发器加热壁面上经常遇到的问题 .垢层严重地降低了换热效率 ,使传热过程迅速恶化 ,蒸发器的防、除垢问题受到人们的普遍重视 .张利斌、李修伦等[1] 研究了汽液固三相循环流化床蒸发器沸腾传热和防、除垢性能 ,本文进一步考察该蒸发器的防、除垢机理 ,并对其进行了分析 .1　汽液固三相流剪应力“混相流”模型根据文献 [1],蒸发管内的汽液固三相流动呈现“混相流”的特性 ,因此为便于分析及突出问题的基本特征 ,假设 :(1)温度场引起的物性变化忽略不计 ;(2 )蒸发管内的汽液两相流动视为均相流动 ,蒸汽的惟一效果是改变了“流体…     

三相循环流化床蒸发器强化传热的研究

采用汽-液-固三相循环流化床新型蒸发器蒸发麦草浆黑液,讨论了热通量、流速和粒子体积分数对三相流沸腾传热系数的影响。试验表明,三相流沸腾传热系数随热通量、黑液流速和粒子体积分数的增加而增大。且对黑液这种高粘度流体使用该蒸发器,其三相流沸腾传热系数比汽液两相流沸腾传热系数提高约20%～30%。     

垂直上升绝热管内汽、液两相流的压降

针对蒸发过程中沸腾层内汽、液两相流的流动状态,对垂直上升绝热管内汽、液两相流流动状态(泡状流和弹状流)中压降的主要部分采用与实际情况相近的模型进行分析,对压降的次要部分采用均相模型和分相模型进行分析,通过积分推出两相流体在区间[Z_1,Z_(1+1)]内总压降的计算式。本文理论计算值与实验结果符合较好。     

低压沸腾管内汽泡尺寸的测量与研究

沸腾工况汽液两相流汽泡尺寸的研究对于深入理解两相流动特性以及相关模型的发展具有重要意义。文中采用双探头光学探针对受热上升管内汽液两相流汽泡尺寸的径向分布特性进行了测量与研究。此外,通过对汽泡尺寸概率密度数的分析,得出了对应工况的两相流流型,根据理论分析及实验结果,总结了汽泡尺寸径向分布与流型的关系。     

垂直管内三相流化床沸腾传热特性

研究了三相流化床沸腾传热的特性和影响传热系数的诸因素。在传热过程中，由于固体粒子的存在，强化了传热。以玻璃球粒子为固相的三相流化床沸腾传热系数，是相同条件下汽液两相流沸腾传热的二倍。以铜粒子为固相的三相流化床沸腾传热系数，是相同条件下汽液两相流沸腾传热系数的３倍。     

尿素低压吸收系统的稳定与优化操作

介绍了影响尿素低压吸收系统稳定操作的主要因素;论述了低调水进口温度控制对系统的影响以及稳定控制低调水进口温度的措施;实施了逐步降低低调水进口温度、稳定缓冲罐液位、去除缓冲罐氮气管线、增加蒸汽盘管等项技术改造措施。结果表明,改造后低调水进口温度由61℃降低到56℃,甲铵液浓度相应得到提高。     

Hydrophobic regions on protein surfaces: definition based on hydration shell structure and a quick method for their computation

The hydrophobic part of the solvent-accessible surface of atypical monomeric globular protein consists of a single, largeinterconnected region formed from faces of apolar atoms andconstituting –60% of the solvent-accessible surface area.Therefore, the direct delineation of the hydrophobic surfacepatches on an atom-wise basis is impossible. Experimental dataindicate that, in a two-state hydration model, a protein canbe considered to be unified with its first hydration shell inits interaction with bulk water. We show that, if the surfacearea occupied by water molecules bound at polar protein atomsas generated by AUTOSOL is removed, only about two-thirds ofthe hydrophobic part of the protein surface remains accessibleto bulk solvent. Moreover, the organization of the hydrophobicpart of the solvent-accessible surface experiences a drasticchange, such that the single interconnected hydrophobic regiondisintegrates into many smaller patches, i.e. the physical definitionof a hydrophobic surface region as unoccupied by first hydrationshell water molecules can distinguish between hydrophobic surfaceclusters and small interconnecting channels. It is these remaininghydrophobic surface pieces that probably play an important rolein intraand intermolecular recognition processes such as ligandbinding, protein folding and protein–protein associationin solution conditions. These observations have led to the developmentof an accurate and quick analytical technique for the automaticdetermination of hydrophobic surface patches of proteins. Thistechnique is not aggravated by the limiting assumptions of themethods for generating explicit water hydration positions. Formationof the hydrophobic surface regions owing to the structure ofthe first hydration shell can be computationally simulated bya small radial increment in solvent-accessible polar atoms,followed by calculation of the remaining exposed hydrophobicpatches. We demonstrate that a radial increase of 0.35–0.50Å resembles the effect of tightly bound water on the organizationof the hydrophobic part of the solvent-accessible surface.     

适用于痕量钴离子迁移的吐温80微乳的制备及迁移条件

研究了以聚氧乙烯失水山梨醇单油酸酯(吐温80)为表面活性剂与不同烃类的油性溶剂及不同醇类的助表面活性剂一起制备的微乳状液对钻离子从水相或料相迁移到微乳相中的影响,同时还观察了油水比和温度对钻离子迁移率的影响,最终得出了以吐温80为表而活性剂,正辛烷为油性溶剂,正庚醇为助表面活性剂的适用于痕量钴离子迁移的微乳体系及最佳迁移条件,结果令人满意.     

努力提高过磷酸钙质量

论述以高浓度肥料作为发展方向的今天,过磷酸钙在我国仍应有其一定的地位。介绍扶余化肥厂在以浓酸矿浆法生产过磷酸钙中,采取的一系列技改措施:磷矿配矿使用,增加破碎,提高矿浆细度,定矿调水法磨矿,定浆调酸法混合等,并对磨矿机、混合器、料浆泵、风机等设备进行技改,使产品质量100%达标。     

Water and methanol crossover in direct methanol fuel cells—Effect of anode diffusion media

Various anode diffusion media have been experimentally studied to reduce water crossover in a direct methanol fuel cell (DMFC). A two-phase water transport model was also employed to theoretically study their effects on water transport and saturation level in a DMFC anode. It is found that wettability of the anode microporous layer (MPL) has a dramatic effect on water crossover or the water transport coefficient (α) through the membrane. Under different current densities, the MEA with a hydrophobic anode MPL has consistently low α, several times smaller than those with a hydrophilic MPL or without an anode MPL. Methanol transport in the anode is found to be not influenced by a hydrophobic anode MPL but inhibited by a hydrophilic one. Constant-current discharge shows that the MEA with hydrophobic anode MPL displays much smaller voltage fluctuation than that with the hydrophilic one. A modeling study of anode water transport reveals that the liquid saturation in the anode is lowered significantly with the increase of anode MPL contact angle, which is thus identified as a key parameter to minimize water crossover in a DMFC.     

AFM measurements of hydrophobic forces between a polyethylene sphere and silanated silica plates- the significance of surface roughness

Recently, substantial research effort has been devoted to the study of non-DLVO forces between hydrophobic surfaces. However, the significance of surface roughness in the analysis of these hydrophobic attractive forces has not been given sufficient consideration and research is now in progress to attend to this issue. Fused silica plates covered with adsorbed octadecyltrichlorosilane (OTS) were characterized by water contact angle measurements and atomic force microscopy (AFM). Surfaces with different surface coverages and different contact angles were obtained by variation of the adsorption time. OTS formed patches on the silica surfaces, the lateral size and height of which depended on the adsorption time. Such surfaces exhibit differences in roughness at the sub-nanometer level. Using the AFM colloidal probe technique, forces between a polyethylene sphere and silanated silica surfaces were measured in water. Long-range attractive forces were found, usually referred to as hydrophobic forces. The resulting force vs. distance curves were fitted with a double exponential function. The magnitude of the short-range part of the force curves seems to correlate with water contact angles at silanated silica surfaces. On the other hand, the range of the long-range force correlates with the roughness of the silanated silica surface. These results with silanated silica surfaces were compared with the AFM results for polyethylene and graphite surfaces and on the basis of these experimental efforts, it appears that the nature of these hydrophobic attractive forces is related to surface roughness.     

纤维素基表面活性剂的研究进展及在造纸工业中的应用

纤维素基表面活性剂具有可生物降解、无污染等特性,具有广泛的应用前景。表面活性剂具有双亲结构,纤维素基表面活性剂通过各种化学改性的方法在纤维素骨架上引入亲水端和疏水端,使整个分子具有表面活性。文章综述了离子型和非离子型纤维素基表面活性剂的合成,以纤维素或其衍生物为原料,通过取代、聚合等方法引入长链烷基等作为疏水基团,离子结构或聚醚结构作为亲水基团,合成的表面活性剂表现出良好的表面性能,并具有高分子表面活性剂的特性。纤维素基表面活性剂在造纸工业中的助留剂和涂料分散剂方面有一定的应用,并有望用于白水处理和废纸脱墨工段。而进一步降低产品的成本并开发更高效、功能更多样的纤维素基表面活性剂将成为未来的研究方向。     

Effects of thickness and hydrophobicity of double microporous layer on the performance in proton exchange membrane fuel cells

In this paper, a multi-layer gas diffusion layer (GDL) is designed. The GDL consists of a single carbon paper backing layer and dual microporous layers (MPLs). Moreover, the effects of thickness and hydrophobicity of double MPL on the performance of proton exchange membrane fuel cells are investigated. From the test results of the water contact angle, conductivity, pore size distribution, and the polarization curve, it is found that the thickness adjustment increases the number of 0.5 to 7 μm and 20 to 100 μm pores in GDL, which is more conducive to water discharge. Therefore, the thickness adjustment is more favorable to the cell performance under high humidity. While the gradient hydrophobic design makes the MPL of the modified intermediate layer have a certain water-retaining capacity to humidify the reaction gas, which has better effect under low humidity. At last, the results show that the optimized GDL meets a limit power density of 1.772 W/cm² under 60% humidification and 1.600 W/cm² under 100% humidification.     

Flash induction calcination: A powerful tool for total template removal and fine tuning of the hydrophobic/hydrophilic balance in SBA-15 type silica mesoporous materials

A new rapid calcination method has been used to completely remove the organic template from SBA-15 ordered mesoporous silica, and to preserve a high number of silanol in these materials. This calcination method provided by an induction furnace was found to considerably reduce the calcination time and therefore the energy consumption associated. Moreover, adjustment of both calcination temperature and duration allowed tuning the hydrophobic/hydrophilic balance of the mesoporous SBA-15 silica materials. For comparison, short and long time conventional muffle furnace calcination was performed. The induction calcination was also successfully applied to different type of mesoporous silica materials such as SBA-16 and MCM-41.     

Hydrophobic recovery and misting behavior of plasma treated PS and PC surfaces

Oxygen plasma treatments of transparent polymers such as polystyrene (PS) and polycarbonate (PC) were performed. Then the hydrophobic recovery of treated surfaces and its effect on their misting behavior was studied. Surface investigations, such as XPS and water contact angle measurements, were combined with the characterization of misting behavior by light transmission methods. In the case of PS it was found that the composition and wettability of the surface layer is insensitive to extraction in water. Hydrophobic recovery leads to decreases of advancing angles upon aging by a mechanism involving macromolecular motions. Misting follows rather closely the behavior of water advancing angles. Oxygen plasma treatment of PC surfaces induces the formation of low molecular weight species which can be extracted by water. Both non-extracted and extracted surfaces were found to undergo hydrophobic recovery with the same mechanism observed in the case of PS. In both cases the misting behavior can be well explained on the basis of wettability.