焦炉吸气管U形氨水联通管系统

本实用新型焦炉吸气管U形氨水联通管系统,其特征是吸气管直接连通到集气管上,在吸气管内部靠近集气管的位置设有吸气管隔板,在吸气管隔板处的吸气管底部设有U型氨水联通管,联通管的一端     

管板与换热管连接结构的优化设计

通过对换热器管板与换热管连接结构形式的分析,尤其是对其中的胀焊结构深入的讨论,选择最适合CO2冷却器的换热管与管板连接方式。     

大直径U形管换热器管板上扇形分区布管形式

对于大直径U形管换热器,如果管板上按常规布管形式布管,最外层U形管的弯曲半径就很大,不但使得外层的U形管弯管段的无支撑跨距很大,容易导致流体诱发的管束振动问题,而且使得最外层与最内层U形管的长度差值很大,将会影响换热器的整体换热性能。我们通过改变管板上的布管形式,在大直径U形管换热器管板上采用扇形分区布管形式,减小了U形管的最大弯曲半径,消除了U形管最大弯曲半径过大引起的诸多不利因素,既可以避免流体诱发的管束振动问题,还可以改善换热管中物料分布的均匀性,提高换热器的换热性能。     

换热管胀管时管板的稳定性

在管壳式热交换器的换热管胀管时,有时发生管板的翘曲,即平衡的平面形状失去了稳定性。这种现象在直径大而管板厚度比较小的热交换器上较常出现。这种现象的发生是基于残余压力的作用,该残余压力发生在换热管与管板接触的地方,那里产生了作用于管板面上的压缩应力。为了算出发生在管板上的压缩应力,我们     

固定管板式换热器管板热应力分析及控制措施

介绍了固定管板式换热器管板设计标准,分析了管板热应力产生机理,寻求减小管板热应力的有效途径,对指导管板设计、优化管板结构及改善换热器性能等具有重要的意义。     

半球形管箱高压U形管换热器管板的强度计算

对一台半球形管箱的高压U形管换热器的管板进行强度计算,该管板与管箱、壳程筒体之间的连接方式不属于GB/T 151-2014标准中列出的结构,不能直接选用该标准中的连接方式计算管板的厚度。根据管板所承受的载荷和受力情况,提出了两种计算方法计算了管板的厚度,并根据换热管中心距对管板计算厚度进行修正。因为两种计算结果比较接近,故认为所采用的计算方法是可行的。鉴于该换热器的管箱是半球形封头,而在第2种方法中将管板当作平盖计算时,现有的设计标准中均没有给出与半球形封头连接的平盖的计算方法,于是先按与圆筒连接的平盖的计算方法进行计算,然后采用ANSYS软件进行有限元应力分析,对计算结果加以验证,验证结果表明所采用的计算方法基本正确的,可用于工程设计。     

固定管板式换热器管板与换热管的可靠性分析

主要利用ANSYS有限元软件对固定管板式换热器管板与换热管进行应力分析,获得了该结构的应力强度分布图,可知该结构的最大应力强度发生在筒体与管板的连接处,最大应力强度为160.133 MPa。然后在应力分析的基础上,利用ANSYS有限元软件中的蒙特卡罗法对该结构进行可靠性分析,经过分析获得了其在置信度为95%且初值极限状态Z〈0（Z=σs-σmax）,其中σs为材料的屈服强度,σmax为容器在使用过程中出现的最大应力）的情形下的概率平均值为3.264 8%,即说明容器的可靠度为96.735 2%,并绘制了Z在置信度为95%的情形下的分布图和输出结果参数的灵敏度图,通过此次分析证明了该固定管板式换热器管板与换热管结构是安全可靠的。     

管与管板的相连

说明管板与换热管连接的问题，并作出了控制其相连质量的方法。     

复合材料身管强迫响应分析复合材料身管强迫响应分析

 为了评价复合材料身管动态特性,在模态分析和阻尼分析的基础上,采用模态叠加动力学有限元计算方法, 对复合材料身管的强迫响应特性进行分析,计算获得复合材料身管的炮口振动情况,并与相同口径的金属身管炮口 响应情况进行比较。结果表明,复合材料身管炮口响应小于金属身管炮口响应,复合材料身管具有更好的动态特性 。     

管板布管限定圆最大布管数的计算

在换热器设备设计中,管板布管数的确定是一个较为繁锁的工作。为此,本文主要介绍应用计算的方法和用IBM-PC/XT 计算机C 语言来确定管板布管限定圆的最大布管数。该方法简便,准确,省时,使用时可根据实际需要选用。     

Interfacial conductivity observation of CaF2 ionic conductor films using Lewis-acidic effect

CaF₂ polycrystalline films were treated with a Lewis acid to form a space charge layer of F^–-vacancies at the adsorbed interface. After the adsorption of SbF₅ molecules on the film, the impedance spectra changed from one semicircle to two semicircles. Investigation of these impedance results, combined with the equivalent circuit models, suggest that the high-frequency semicircle may be ascribed to the high conduction layer connected in parallel with bulk conduction and the low frequency semicircle suggests the blocking effect of a perpendicular barrier for the current flow. Numerical estimation is reasonably consistent with this model. This confirms that space charge layers composed of ion vacancies can be systematically created using the chemical attractive force of Lewis acids.     

A new approach to the mechanism of chlorine evolution: Separate examination of the kinetic steps using ac impedance on a rotating thin ring electrode

In the absence of a bulk diffusion effect, it is shown for the first time that the impedance spectra for the chlorine evolution reaction on a rotating thin ring electrode comprise three consecutive semicircles in the capacitive half of the complex plane. The first (highest frequency) semicircle is due to the charge-transfer resistance for chloride discharge and the simultaneous chlorine adsorption coupled to the double-layer capacitance. The second semicircle (around 5 Hz) is due to the adsorption and desorption of a chlorine intermediate. The third (lowest frequency, around 0.5 Hz) semicircle is due to the relaxation of surface oxygen species. The impedance data allow the steps of the overall reaction to be examined individually. On a Pt surface the rate of chloride discharge and simultaneous chlorine adsorption (the admittance of the first semicircle) is first order with respect to chloride concentration and has a potential-dependence close to 58 mV/decade. The rate of the adsorption and desorption process (the admittance of the second semicircle) is second order with respect to chloride concentration, and has a potential dependence close to 30 mV/decade. The time constant for the adsorption/desorption processes is ca 20 ms, independent of electrode potential in the range studied. These features are consistent with a mechanism in which a faster discharge reaction (Cl⁻ Cl_ad + e) is followed by a slower surface combination reaction (2Cl_ad → Cl₂), but inconsistent with mechanisms in which ion + atom desorption is predominant, the initial chloride discharge is slow, or a unipositively charged chlorine species is involved.     

Miscible and immiscible blends of ABS with PMMA. I. Morphology and rheology

Melt blends of ABS and PMMA were prepared using three types of ABS having different acrylonitrile (AN) content, and PMMAs with different MW. From TEM micrographs, it was found that ABSs containing 24 and 27 wt % AN were miscible, and the one containing 35 wt % AN was immiscible with PMMA. Morphologically miscible blends showed welldefined semicircles in Cole—Cole plots, whereas immiscible ones showed immiscible drifts from the semicircle. In addition, as the compounding temperature increases, the dispersed PMMA phase became stratified, and more rubber particles, especially larger ones, migrated toward the PMMA phase. Miscible blends gave viscosities lower than additivity would predict, whereas immiscible ones gave positive (ABS-rich phase) and negative (PMMA-rich phase) deviations from the additivity. © 1993 John Wiley & Sons, Inc.     

Superior Perovskite Oxide-Ion Conductor; Strontium- and Magnesium-Doped LaGaO3: II, ac Impedance Spectroscopy

Alternating current impedance spectroscopy and electron microscopy were used to investigate the effect of grain boundaries in LSGM-based materials. The impurity LaSrGa₃O₇ existing in the samples La_0.8Sr_0.2Ga_{1- y} Mg _y -O_{3–0.5(0.2+ y )} ( y = 0.05–0.10) gives a contribution to a perfect or depressed grain-boundary semicircle in the impedance spectroscopy. The depressed semicircle represents a constant phase element (CPE) indicating LaSrGa₃O₇ is an oxide-ion insulator. The grain-boundary semicircle vanishes if a hydrogen-containing atmosphere is applied. This fact may reflect proton conduction in LaSrGa₃O₇. In contrast, the impurity LaSrGaO₄ existing, for example, in the samples x = 0.20, y = 0.25–0.30 gives no grain-boundary contribution to the impedance.     

AC impedance and state-of-charge analysis of alkaline zinc/manganese dioxide primary cells

Alternating current impedance data of alkaline Zn/MnO₂ cells were analysed in view of identification of suitable parameters, which depend on the state-of-charge (SOC) of the cells. The impedance of a slightly discharged cell was found to possess impedance considerably lesser than that of an undischarged cell. The data in the form of Nyquist plot contained an inductance part at very high frequencies, a capacitive semicircle at high frequencies and a diffusion linear spike at low frequencies. The low frequency linear spike gradually transformed into a capacitive semicircle with the decrease of SOC of the cell, which was attributed to the nature of the reactions at the Zn anode. Of several impedance parameters that were examined, equivalent series capacitance (C _s) was found to have a strong dependence on SOC of the alkaline Zn/MnO₂ cells. There was a continuous change in a partially discharged cell during its ageing, which was reflected by transformation of low frequency data into a clear semicircle.     

电机轴承半圆盒状顶盖翻转式顶出脱模机构设计

针对电机轴承半圆盒状顶盖塑料件在其型芯一侧两端同时存在结构相同并向中间凸出的半圆状扣位难以顶出脱模的结构特征,设计出特殊的旋转式头部成型组件及其控制组件,在控制组件的控制下实现成型转动块的圆弧路径翻转式型芯脱模,简化了塑料件两端型芯采用传统机构脱模带来的机构复杂性,所设计机构能在同一注塑模具内一次整体成型塑料件,有效地降低了模具的生产制作成本,结构设计巧妙,工作稳定可靠。     

乳液聚合螺旋半园管夹套反应釜

本文将螺旋半园管夹套反应釜与传统的夹套反应釜进行了对比 ,并介绍了螺旋半园管夹套釜在乳液聚合中的应用     

Effect of Porosity on the Electrical Properties of Polycrystalline Sodium Niobate: I, Electrical Conductivity

The electrical behavior of NaNbO₃ ceramic samples with different relative densities was investigated by ac impedance spectroscopy in a range of 13 MHz to 10⁻³ Hz between 400° and 800°C in dry air. Measurements were performed during heating and cooling cycles. The Nyquist impedance diagrams of dense sodium niobate exhibit only one semicircle representing the grain contribution with depression angles as small as 1°, indicating a high homogeneity of the specific electrical properties. In the case of porous samples, the data reveal an additional low-frequency semicircle related to microstructure. For all studied samples, the Arrhenius conductivity plots show a change in the activation energy around 640°C, attributed to the tetragonal-cubic phase transition. The electrical conductivity of porous samples appears to be higher than that of dense ones.     

硫铁矿沸腾炉内蒸发管组防磨技术的探讨

为减少磨损,沸腾炉内蒸发管采用加焊半圆形钢板防磨.探讨了沸腾炉内蒸发管加焊半圆形钢板的防磨机理.实际使用情况表明,加焊半圆形钢板防磨大大降低了维修费用,显著提高了防磨效果.     

Study of pyrite oxidation by cyclic voltammetric, impedance spectroscopic and potential step techniques

Pyrite oxidation in chloride solutions was investigated with cyclic voltammetry, a.c. impedance and potential step techniques. The oxidation reactions of pyrite were examined by cyclic voltammetric technique and a two-step reaction with a passivation film forming as a first-step product was proposed. An equivalent circuit was then postulated based on the oxidation reactions. Parameters indicated in the equivalent circuit such as reaction resistance and pseudo-capacitance caused by the passivation film, were determined by a.c. impedance measurements. A mathematical formula was derived from the concept of the equivalent circuit to explain the depression of the semicircle in the complex plane plot. When the semicircle is depressed, the mathematical formula indicates that the reaction resistance should be obtained from the intersection of the semi-circle with Z-axis instead of the semicircle diameter. Potential step chronoamperometric technique was then applied to measure the charging current, which is caused by the pseudo-capacitance of the passivation film, to examine the proposed equivalent circuit. The peak charging current densities at 1.10 and 0.90 V vs SHE obtained from the equivalent circuit and the a.c. impedance measurements are 110 and 75 mA cm^–2, respectively. They are consistent with the peak current densities of 105 and 69 mA cm^–2 at 1.10 and 0.90 V, respectively, determined by the potential step chronoamperometric measurements.