机织过滤介质的流体透过性研究

引言机织过滤介质,又称机织滤布,是固液分离领域应用最为广泛的一种过滤介质．滤布的透过度和透水速率的高低直接反映这类过滤介质过滤指标的好坏,因此,研究机织过滤介质透过度和透水速率的变化规律及影响因素对实际过滤作业中合理选择机织滤布具有指导意义．1理论分析机织过滤介质内的孔隙可以分为3类：织物内纱线间孔隙、纱线内纤维间孔隙和纤维上的孔隙．研究表明［1],对流体透过过滤介质起作用的孔隙主要是织物内纱线间孔隙和纱线内纤维间孔隙,因此,假设机织过滤介质总的透水速率是流体通过过滤介质内两类孔隙时的透水速率之和,…     

机织过滤介质的流体透过性研究

机织过滤介质透过度在测试过程中随时间具有渐变性，这是由于流体中的微气泡在介质孔隙壁上的析出而造成，在测试中以介质两侧压差达到稳定并持续不超过１０ｍｉｎ所得到的透过度作为介质透过度的真值在统计学上是完全合理的。影响透过度大小的因素主要包括介质纱线类型、组织结构、孔径和孔隙度以及纤维的润湿性等     

锯齿翅片的传热与阻力性能试验

在风洞试验台上对16种不同结构参数的板翅换热器中使用锯齿翅片进行了传热和流动阻力性能试验,分析比较了翅片间距和翅片长度对其表面对流传热系数和空气阻力性能的影响。同时通过对16种翅片的244个试验数据点进行多元回归和F显著性检验，获得了j因子和f因子的经验关联式。在Re=500～7500范围内，经验关联式的最大误差范围为±10%，绝对平均偏差分别为4.2%和5.3%。     

紧凑换热器传热实验平台设计

为研究管翅式和板翅式两种紧凑换热器的传热特性、阻力特性以及它们的性能评价,设计了一套基于GCMS组态软件的传热性能实验平台。该实验平台可用计算机测控系统进行数据采集和流程控制;用Wilson图解法确定对流换热系数,并拟合出努塞尔准则关系式;可得到△P=f(u)和Eu=f(Re)力特性曲线;可用熵分析法和Yong分析法对换热器进行性能评价。     

幂律流体湍流摩擦因子的简化计算式

<正> 为了计算非牛顿流体沿管内流动的摩擦阻力损失,需要求取摩擦因子。非牛顿流体在管内呈层流流动时,其摩擦因子的计算式与牛顿流体层流流动的计算式类似: f=16/Re’(1)式中Re’为广义雷诺准数,幂律流体的广义雷诺准数可按下式计算: Re’=D~nU_m~(2-n)ρ/(k/8((6n+2)/n)~n) (2)上式中: D—管子直径,米 U_m—流体平均流速,米/秒ρ—流体密度,千克/米~3 n—流动行为指数 K—稠度指数,牛顿·秒~n/米~2 对于幂律流体在管内的湍流流动,普遍采用Dodge等人导出的隐函关系式计算湍流摩擦因子: 1/(f~(1/2))=4.0/n~(0.75)log(Re’f~(?-n/2))-0.4/n~(1.2)(3)显然,可用数值方法由上式求解摩擦因子f。虽然可以用图解法从f对Re’的关联图上直接查得一定n和Re’值下的f值,但关联图     

精密单丝滤布透水速率与截留精度的研究

为进一步了解液固分离用织造滤布的过滤性能,以液固分离用新型过滤介质精密单丝滤布为研究对象,对滤布结构、开孔大小、丝径、孔隙率等因素对透水速率的影响进行了理论分析与讨论;并采用国际标准规定的鼓泡孔径、透水速率和截留精度的测试方法,对几种精密单丝滤布的孔径大小、透水速率、截留精度、透水阻力、孔隙度、分离效率进行了实验测定;同时介绍了不同孔隙度及截留精度的测定方法和结果,并对截留精度经验计算进行了实验验证,对正确选择与科学使用过滤介质单丝滤布提供有益的参考。     

(1-x)Ba4Sm9.33Ti18O54-xCa0.61Nd0.26TiO3系微波介质陶瓷

采用固相合成法制备了(1-x)Ba4Sm9.33Ti18O54-xCa0.61Nd0.26TiO3[(1-x)BST-xCNT]系微波介质陶瓷.探讨了组成、烧结温度对微波介质陶瓷结构、介电性能的影响.x＜0.6时,(1-x)BST-xCNT陶瓷为正交结构的新型钨青铜单相.x≥0.6时,相继出现了第二相Sm2Ti2O7和钙钛矿相,最终形成钙钛矿单相.微波介质陶瓷的介电常数ε随x的增大持续升高,品质因子Qf值则先增大后迅速减小再急剧增大.1 325～1 350 ℃烧结样品的微波介电性能达到最佳:x=0时,ε=75,Qf=8985GHz,谐振频率温度系数τf=-8.2×10-6/℃;x=0.2时,ε=75,Qf=9 552GHz,τf=-14.4×10-6/℃;x=1时,ε=108.9,Qf=14919GHz,τf=236.2×10-6/℃.     

Ca_(0.6)La_(0.8/3)TiO_3-Li_(0.5)Sm_(0.5)TiO_3复合微波陶瓷的介电性能

采用传统固相合成法制备了xCa0.6La0.8/3TiO3-(1-x)(Li0.5Sm0.5)TiO3(CLT-LST)系列微波介质陶瓷材料,研究了该系列微波介质陶瓷的物相结构、表面形貌、介电性能。实验发现:随着Ca0.6La0.8/3TiO3含量的增多,CLT-LST样品XRD峰轻微左移。陶瓷组成对微波介电性能影响显著,复合体系CLT-LST的微波介电性能随着x值不同而连续变化:当x从0.2上升到0.6时,介电常数(εr)逐步增大,在x=(0.4~0.6),εr变化趋于稳定,达到较佳值;品质因数(Q·f)则先减小后增大再迅速减小;谐振频率温度系数(τf)逐渐从负值向正值方向移动。当复合体系组成为0.4Ca0.6La0.8/3TiO3-0.6(Li0.5Sm0.5)TiO3时,在1 250℃烧结4h所得到的微波介电性能较佳,εr=125;Q·f=2 680GHz;τf=7.0×106/℃。     

池式沸腾人工汽化中心表面汽泡脱离频率的研究

本文在人工汽化中心表面上,考察了核状池式沸腾过程中,表面过热度、孔径对汽泡脱离频率的影响.实验是在常压下进行的,以脱离子水、乙醇、正丙醇为介质,孔径范围为0.15—0.30mm.对实验结果进行了关联,得到如下无因次方程f/(σ~2ρ_1c_p/μ~2λ_1)=1.40×10~(-6)(ρ_v/ρ_1)~(1.08)(We/Re~2_b)~(1.16)Ja~(1.43)/Pr~(0.06)在前人工作基础上,本文建立了描述汽泡脱离频率与表面过热度和孔径之间关系的数学模型,计算值与实验值符合良好.     

纺丝组件中多孔介质对PA6熔体流动性能的影响

在毛细管流变仪上增加多孔介质金属过滤砂,研究了聚己内酰胺(PA6)熔体通过不同过滤精度的多孔介质时的流动规律。结果表明:随着多孔介质过滤精度与熔体流动速率的增大,PA6熔体的压力增加值增大;PA6熔体压力增加值与流动速率关系可用Forchheimer方程较好地描述,其方程的拟合相关系数均大于0.997,粘性阻力因子(1/k)与惯性阻力因子(β)都随多孔介质过滤精度的增加而增加,当温度为265℃时,β较1/k大2个数量级;随着熔体温度的升高,1/k与β均减小;在实验条件下,PA6熔体的压力增加值主要来自粘性损耗,但随着流动速率的增加,惯性损耗增加,过滤精度越高,惯性损耗增加越明显。     

滤布阻力对恒压过滤最佳操作周期的影响

导出考虑滤布阻力时恒压过滤最佳操作周期的严格公式,并给出了忽略滤布阻力对最佳周期影响的严格判据(M-判据),对该判据的研究表明,当过滤辅助时间较短时,简单地根据滤布阻力当量滤液量和实际滤液量之比(Ve/V)来判断能否忽略滤布阻力对最佳操作周期的影响是不够充分的。     

Influence of cloth structure on dust dislodgement from fabric filters

The residual dust loading and filter drag (flow resistance) of fabric filters after reverse pulse cleaning are strongly dependent on cloth structure. Filament/spun combination fabrics have smaller residual dust loadings but greater residual filter drags than all spun cloths. Calendered needlefelts have smaller residual dust loadings but greater residual filter drags than untreated felts. The dust-cake specific resistance coefficient was found to be independent of cloth structure.     

Analysis of Filtration Characteristics for Compressible Polycrystalline Particles by Partial Least Squares Regression

Crystal size and morphology have been varied by changing the initial supersaturation ratio and the temperature in reactive crystallization experiments. The influence of the chord length distribution, average cake porosity, and filtration pressure difference on the average cake resistance of polycrystalline particles of an industrially produced aromatic amine has been investigated by means of partial least squares (PLS) regression and sensitivity analysis. Analysis of the results has disclosed that wider chord length distributions as well as lower values of the measured average porosity lead to higher values for the average cake resistance. However, PLS regression and sensitivity analysis have identified the applied pressure difference itself as the most significant parameter influencing the magnitude of the cake resistance. This unexpected behavior is accounted for by compression of the filter cake occurring predominantly in small layers above the filter cloth characteristic for highly compressible cakes.     

电力行业用新型高防酸处理玻纤布覆膜滤料的性能研究

针对电力行业酸性烟气工况的特点,开发了新型高防酸处理玻纤布覆膜滤料。对比研究了新型高防酸处理与常规处理玻纤布覆膜滤料的防酸性能、防水性能,结果显示新型高防酸处理玻纤布覆膜滤料相比普通玻纤布覆膜滤料具有明显的防水、防酸优势。     

0.7CaTiO3-0.3Sm1-xAlO3陶瓷微波介电性能研究

采用固相反应法制备了0.7CaTiO3-0.3Sm1-xAlO3(CTSA,0≤x≤0.1)微波介质陶瓷,研究了Sm缺位对CTSA陶瓷的晶体结构、微观形貌以及微波介电性能的影响。结果表明,制备的CTSA陶瓷均为正交钙钛矿结构。少量的Sm缺位能够降低CTSA陶瓷的烧结温度,晶粒尺寸增加,同时气孔率增大,陶瓷的Q×f值也有显著提升。当x=0.025、烧结温度为1450℃时,CTSA陶瓷具有最佳微波介电性能:εr=45.2,Q×f=47280GHz和τf=+4.8 ppm/℃。     

A model analysis on the reasons for unstable operation of jet-pulsed filters

Various physically based models are available to describe an uneven distribution of the filter cake on the filter area of jet-pulsed bag filters. Such an uneven distribution is intrinsically present, when only segments of the filter are cleaned at a time but not the entire filter. Moreover, also patchy cleaning causes an uneven filter cake loading, since only a fraction of a filter cake is removed by a jet pulse while the other fraction remains basically intact on the filter cloth. Unstable filter operation can be defined by a continuous or periodic reduction of the filtration time per cleaning pulse. The operation of a jet-pulsed filter was mathematically simulated and, by systematically altering model parameters, unstable operation was obtained. Three situations were investigated: a continuous increase of the filter cake resistance parameter, a continuous increase of the filter cloth resistance parameter, and a particular cake detachment function where, after a filter cake survived some filter cycles, it can hardly be removed. The transient pressure difference simulation results reveal characteristic patterns: Taking normal stable operation as a reference, an increase of the filter cake resistance leads to shorter filtration and somewhat longer cleaning intervals (i.e., more cleaning pulses). An increase of the filter cloth resistance causes longer filtration and also considerably more cleaning pulses. Deficient filter cleaning gives shorter filtration periods and extremely long cleaning intervals. A comparison between model simulations and pilot plant results shows that there, the experimentally observed unstable operation can most likely be attributed to problems with cake detachment. Hence appropriate measures for avoiding unstable operation were successfully introduced.     

磷酸装置转盘式过滤机板网改进及运用

云峰分公司磷酸厂转盘式过滤机板网孔眼及滤盒内结垢堵塞严重,液相穿透性能差,导致过滤系统非计划停车频繁,过滤装置出现硫酸消耗、滤布消耗、水溶磷含量高,磷收率、洗涤率和滤布再生效果低的三高三低现象。经分析发现,过滤机板网和滤盒本身设备结构不合理,滤板透气性能差是结垢的主要原因。通过采取针对性的解决措施,降低了过滤机板网及滤盒内结垢速率,磷收率由96.84%提高至97.31%,实现了过滤机清理检修周期与滤布更换周期同步。     

The correlations between structural and optical properties of magnetite nanoparticles synthesised from natural iron sand

The correlations between structural and optical properties of magnetite (Fe₃O₄) nanoparticles were analyzed by using X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) Spectroscopy. The magnetite was synthesised from the iron sand using NaOH, HCl, and NaCl as a solvent. From the quantitative analysis of XRD spectra, the crystallite size (D), strain ($\epsilon$), stress ($\sigma$), energy deformation (u), porosity, and specific surface area were determined. The Kramers Kronig (K–K) relations was applied to the FTIR spectra to determine the optical properties: refractive index (n), extinction coefficient (k), the complex dielectric function ($\mathit{\epsilon }$), and the energy loss function (Im(-1/ε)). The uniform strain was produced from the NaOH and HCl as the solvent. The magnetite had higher porosity with NaCl as a solvent and was directly proportional to the optical phonon vibration. We found a perfect correlation; when the difference between two optical phonon increases, the crystallite size decreases, and the strain will be uniform.     

Effect of diluents and/or fortifier on the glass fiber–epoxy composites

The glass fiber-epoxy composites were fabricated with the E-type glass cloth and diglycidyl ether of bisphenol A (DGEBA) using 12% diethylenetriamine (DETA) as catalyst on the basis of DGEBA. The properties were modified by incorporating diluents such as epoxidized 2,2,6,6-tetramethylolcyclohexanol (ETMC) and 1,4-butandioldiglycidyl ether (BDDE) with/without 20 parts per 100 g of a condensation product of phenyglycidylether and 4-hydroxyacetanilide (PGEHA) employed as fortifier. The characterization of these epoxy laminates includes resistance to chemical reagents, dynamic mechanical analysis, and mechanical properties like flexural strength, impact strength, and hardness. The dielectrical properties such as breakdown strength, dielectric constant (ε′), dielectric loss (ε″), and loss tangent (tan δ) were estimated.