外压锥形封头设计和开孔处的应力强度

本文对外压锥形封头设计以及开孔接管处的应力强度等两个问题进行分析。     

外压锥形封头设计和开孔处的应力强度

本文对外压锥形封头设计以及开孔接管处的应力强度等两个问题进行分析。     

基于有限元的压力容器开孔接管区的应力分析及优化设计

采用有限元法研究开孔接管区域的应力分布规律,对危险区域进行应力强度评定。结果表明:开孔接管区域应力分布复杂,梯度变化明显;最大应力发生在筒体与接管连接区域的内侧且对称分布,是筒体失效的最危险区域。在保证压力容器安全运行的工况下,对容器的结构进行优化设计,分析计算得到容器的最优解,保证容器高效安全运行的同时降低制造成本。     

温差变化工况下接管螺纹接头密封形式的改造

分析了温差变化工况下设备内部接管密封失效的原因,通过将传统平面密封形式改为函式的O形圈密封,将螺纹接头接管改为内外双套管等方式及将原普通螺纹接头改为O形圈函式密封和迷宫密封结合的特殊结构,解决了在温差变化工况下接头松动导致平面密封压力不足而产生泄漏的问题。     

夹套容器平齐接管在温差作用下的疲劳分析

对气化炉夹套平齐接管处的温差应力进行了有限元分析计算,并对内筒温度的变化引起的疲劳问题进行了分析研究,按照分析设计标准JB4732-95进行了疲劳强度评定,得出的结论对类似设备的设计有参考价值。     

半圆管夹套容器温差情况下半圆管应力计算

本文对半圆管夹套容器在内外介质的温差情况下的半管应力进行了分析,给出了半圆管的温差应力计算公式,同时给出了使半圆管不失效条件下筒体内介质的最大工作温度条件式。     

苯乙烯脱氢反应器腐蚀失效分析及对策

针对304H反应器锥形上封头焊缝出现裂纹的问题,通过对裂纹宏观形态、材料力学性能、腐蚀产物、金相组织和结构应力等方面的综合分析,发现失效形式为沿晶型应力腐蚀。结合实际生产经验提出了修复和检测的针对性措施。     

夹套容器平齐接管在温差作用下的疲劳分析

对气化炉夹套平齐接管处的温差应力进行了有限元分析计算，并对内筒温度的变化引起的疲劳问题进行了分析研究，按照分析设计标准ＪＢ４７３２－９５进行了疲劳强度评定， 了的结论对类似的设计有参考价值。     

壳管式换热器启动过程中管壳间温差数值计算和应力分析

以中原乙烯运行的由CTIP公司提供的壳管式换热器为例 ,建立非稳态传热数学模型 ,进行数值求解 ,计算出启动过程中各个时刻的管壳间温差 ,并分析对此温差的影响因素。进一步对炉管进行启动过程应力分析 ,并提出减轻造成炉管失效的附加应力因素的措施。     

苯酐冷凝器应力腐蚀原因研究

描述了苯酐冷凝器应力腐蚀失效的现状,详细研究分析了产生应力腐蚀的拉伸应力、腐蚀环境、材质影响等三大原因,并针对这些原因提出了消除残余应力、降低温差应力、改善冷却水质、优化操作工艺、选用对应力腐蚀不敏感的材料等优化和改进措施.     

两类混合机对粉料分散影响研究

固态混合的形式有对流混合、扩散混合和剪切混合,本文以涂料粉料组分为研究对象,采用螺杆输送立式锥形混合机、双螺旋锥形混合机2种类型混合机进行试验,研究2种不同类型混合机对粉料分散效果影响。通过粉料样品对比、试样样板比对,结果表明:采用螺杆输送立式锥形混合机生产丙组分混合效果比双螺旋锥形混合机效果好,同样粉料因混合效果差异会导致色差。     

On the Movement of a Fluid Medium of Constant Density in Cylindrical and Conic Channels

The movement of a fluid medium of constant density in cylindrical and conic channels -- analogs of the operating space of continuous reactors of industrial power plants -- is considered. Special and generalized formula are derived that relate fluid parameters to the geometry of cylindrical and conic channels; properly modified, the formulas can be used for a design analysis of the reactor's operating space. An example of design formulas is given.     

Evolution of aluminum nitride nanostructures from nanoflower to thin film on silicon substrate by direct nitridation of aluminum precursor

Herein we demonstrate a convenient regulation of several aluminum nitride nanostructures through direct nitridation of aluminum precursor under different conditions. Different AlN nanostructures including conic nanoflowers, nanowires, quasi-aligned nanocones and polycrystalline thin film have been obtained on the Au-coated Si substrates just simply by decreasing the reaction temperature or changing the reaction procedure, and a four-stage growth mechanism is hereby deduced. The conic nanoflower composed of AlN nanocones is an interesting geometry. The photoluminescence and field emission measurement revealed that these AlN nanoflowers own a broad blue emission band and a rather good field emission property, suggesting the potential applications in light and field emission nanodevices.     

注射过程喷嘴内物料温度和压力的模拟与分析

利用Fluent软件对注射过程中物料在喷嘴内的流动进行了模拟,分析了喷嘴内剪切热产生的位置及喷嘴尺寸与物料温度变化和压力降的关系。结果表明,注射过程中喷嘴内最高温升位置出现在壁面附近的很小区域内,温升变化率随喷嘴圆管直径的增加而降低,随喷嘴圆管长度的增加而提高;喷嘴出口处物料温度随喷嘴圆管直径增加逐渐趋向均匀;注射过程中喷嘴内压力降随喷嘴圆管直径减少和长度的增加而提高。     

Gas entrainment characteristics of diesel spray injected by a group-hole nozzle

In this study, gas entrainment characteristics of a diesel spray injected by a group of closely spaced two-orifices (group-hole nozzle) were investigated. Both free and wall-impinging sprays were considered. The gas entrainment characteristics of the group-hole nozzle spray were compared to those of single-hole nozzle sprays: one has the same total hole area with the group-hole nozzle, and the other has the same hole diameter. The gas entrainment characteristics of diesel sprays were investigated using a particle image velocitmetry technique coupled with a laser induced fluorescence technique (LIF-PIV technique).The spray tip penetration of the group-hole nozzle was the shortest among the applied nozzles in a free spray condition, while it was the longest in a wall-impinging condition. In the free spray condition, the gas entrainment of the spray was enhanced by the group-hole nozzle due to extensive momentum exchange with surrounding gas and superposed gas entrainment motion of the two-jets injected by the group-hole nozzle. After wall-impingement, the group-hole nozzle spray showed a stronger wall-jet vortex and increased gas entrainment compared to the single-hole nozzle sprays due to enhanced spray/wall interaction caused by the momentum interaction of the two-jets from the group-hole nozzle. Asymmetric shape of the group-hole nozzle spray resulted in an asymmetric gas velocity distribution of the spray both in the free and wall-impinging conditions.     

Designing a Jet Mill Nozzle of Maximum Efficiency

A method of calculation for an accelerating jet mill nozzle profile which provides a maximum kinetic energy for solid particles at the nozzle outlet, is developed. The gas‐solid flow in the nozzle is described by a well‐known one‐dimensional model. The effect of both solid loading and particle size on the optimal nozzle profile, as well as on the main flow parameters is studied. Distribution of particle velocities in the computed optimal nozzle is compared to that in a conical convergent‐divergent nozzle of the same length. Computations demonstrated that optimized nozzles are profitable for fairly low solid loadings. The kinetic energy of solids at the optimized nozzle outlet is about 50% higher than that in a conical nozzle if the solid/gas mass flow ratio equals unity.     

湿式烟气脱硫管路布置的比较试验

通过对湿法脱硫中常采用的螺旋喷嘴和旋流喷嘴在塔内的不同布置方式进行试验。试验表明,螺旋喷嘴比旋流喷嘴能形成更大的水膜,螺旋喷嘴中又以单层水膜和下层管路在同一侧所成的水膜破坏最小。     

Coaxial electrohydrodynamic atomization toward large scale production of core‐shell structured microparticles

In this work, a double‐nozzle coaxial electrohydrodynamic atomization (CEHDA) system was designed as an instructive case toward large‐scale production of core‐shell microspheres. The effect of nozzle‐to‐nozzle distance was investigated to reveal that the interference between neighboring nozzles significantly affect the product quality in terms of morphology and core‐shell structure. Optimal spacing indicated that ～3000 nozzle/m² packing density may be achieved with minimum interference of electric field from neighboring nozzle by adjusting the nozzle‐to‐nozzle distance greater than 0.018 m. The proposed multi‐scale model also showed that the X‐component of electric field strength (E_x) at the region near side nozzles increases with increasing nozzle number, and the bending of jets/sprays at the side may be reduced by using dummy nozzle at the edge side. The model could guide the design of multi‐nozzle CEHDA system for production of core‐shell microparticles in large‐scale. © 2017 American Institute of Chemical Engineers AIChE J, 63: 5303–5319, 2017     

陶瓷过滤器脉冲反吹用喷嘴优化设计

The experimental study was carried out to optimize the nozzle shape and dimension for the pulse cleaning of a ceramic filter candle. A bench scale unit of ceramic filter consisting of four commercial filter elements was used to measure the traces of the transient pressure around the nozzle and the overpressure in the filter cavity during the pulse-jet injection of pulse gas. Overpressure in the filter cavity is related to the pulse cleaning force. Nozzle design is concerned to increase the overpressure at the open end of filter element of pulse cleaning inlet, as well as to minimize the consumption of pulse gas. Convergent nozzle induces more secondary flow and generates higher pulse cleaning effect than straight nozzle. Nozzles of different convergent ratio （ratio of outlet to inlet diameter of nozzle） by changing the convergent angle and height were tested. The outlet diameter of convergent nozzle seriously influences the cleaning effect. The optimum convergent ratio increases with the increase of pulse gas pressure The nozzle position （distance of nozzle tip from the open end of filter inlet） is also important to decide the nozzle dimension. Nozzle of large outlet diameter accepts high pressure of pulse gas to provide large overpressure in the filter cavity of top position by applying long distance.     

Numerical and experimental investigations on NANO-SIO2 jet polishing efficiency by different nozzle structures

This paper focuses on the fused silica material removal efficiency with different nozzle structures during nano-SiO₂ jet polishing. The removal function and flow field distribution are with different nozzle structures obtained from the numerical and experimental investigations. The results show that under the same conditions, the removal efficiency of single-slit nozzle is 2.55 times that of single-hole nozzle, and the removal efficiency of multi-slit nozzle is 1.65 times that of the single-slit nozzle. The optimal length and width of a single slit is 5 mm and 0.6 mm, respectively. Finally, the variation of surface roughness is obtained with slit nozzle structure. With the increase of removal depth, the surface roughness of fused silica decreased from 1.86 nm to 0.491 nm, which further verified that the slit nozzle can quickly achieve super-smooth machining of fused silica surface during nano-SiO₂ jet polishing.