自动再循环阀在离心泵最小流量控制中的应用

介绍一种控制离心泵出口最小流量的自动控制阀门———自动再循环阀 (ARC)的结构、工作原理及其选用和管路设计。此阀可一阀代两阀 ,使离心泵平稳运行 ,使用方便且节省能量和投资。     

卧式热虹吸再沸器的压力平衡计算

由传热设计软件HTRI7.0对石油化工装置中常用的卧式热虹吸再沸器的工艺设计过程进行详细介绍。文章主要研究了卧式热虹吸再沸器基于压力平衡下的再沸器安装高度的计算方法及步骤,得出了卧式热虹吸再沸器的阻力损失包括再沸器入口管线阻力损失、再沸器内的阻力损失和再沸器出口管线阻力损失三部分,其中,再沸器出口管线为两相流,其阻力损失计算采用分离模型计算的误差小,准确度高。根据上述工艺设计方法,以某甲醇制烯烃（MTO）装置中一台水汽提塔再沸器为例,分析了该再沸器开工时出口管线振动的原因是由于推动力过大导致两相流流型为不稳定流型从而引起操作不稳定,并给出合理的改造和解决方案,即在再沸器入口管线增加手动调节阀。     

安全阀排放管道支架设计

分析和研究安全阀排放管支架的设计。通过分析和计算所受的力和力矩,介绍安全阀排放管道支架的设计方法。     

Numerical calculation and experimental validation of safety valve flows at pressures up to 600 bar

A numerical valve model has been validated to predict the discharge capacity in accordance to the requirements of valve sizing method EN ISO 4126‐1 and the opening characteristic of high‐pressure safety valves. The valve is modeled with computational fluid dynamics software ANSYS CFX, and the model is extended with the Soave‐ Redlich–Kwong real‐gas equation of state to allow calculations at pressures up to 3600 bar. A unique test facility has been constructed to perform valve function and capacity tests at operating pressures up to 600 bar with water and nitrogen. For gas flows, the numerical results and the experimental data on mass flow rates agree within 3%, whereas deviations in flow force are 12% on average. The inclusion of fluid‐structure interaction in the numerical method improves the results for the flow force well and also gives insight into the valve dynamics of an opening safety valve. In a comparison between the experimentally and numerically determined liquid mass flow rates, a model extension accounting for cavitation reduces overpredictions by a factor of 2–20% for smaller disk lifts and decreases the deviations in flow force from 35 to 7%. At higher disk lifts, the effect of cavitation is less, and experimental and numerical mass flow rates agree within 4% and flow forces within 5%. © 2011 American Institute of Chemical Engineers AIChE J, 2011     

石油化工装置安全阀的选用及配管设计

本文介绍了石油化工装置安全阀的分类,选用的原则,安全阀的安装及进出口的配管设计要求。     

Extents of reaction and flow for homogeneous reaction systems with inlet and outlet streams

For homogeneous reaction systems with inlet and outlet streams, this article proposes a linear transformation of the number of moles vector into three distinct parts, namely, the reaction variants, the inlet‐flow variants, and the reaction and inlet‐flow invariants. The transformed states can be interpreted physically as (i) the amount of material contributed by each reaction and still present in the reactor (extents of reaction), (ii) the amount of material contributed by each inlet stream and still present in the reactor (extents of inlet flow), and (iii) the fraction of the initial conditions that has left the reactor (extent of outlet flow). Furthermore, several implications of being able to compute the extents of reaction and inlet flow are discussed. The methodology is illustrated in simulation via the ethanolysis of phthalyl chloride. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

关于埋地管道检验检测的必要性及建议

管道企业开展管道检验检测是必要的,其在满足国家法律法规要求的同时,能延长管道使用寿命、降低管道企业安全事故风险。在选择管道检验检测方法时,管道企业需根据输送介质、土壤环境、地区级别、运行年限、是否施加有效阴极保护、是否掌握管道失效的初步原因及泄漏等安全事故的位置分布等因素。外腐蚀直接评价(ECDA)作为钢制管道外腐蚀检测方法之一,其在国内的广泛应用实例已证明具有很好的适用性,它能帮助管道企业获得管道系统的外防腐层质量状况、阴极保护系统、杂散电流干扰、管体最可能失效位置等相关数据,为管道企业采取有针对性的维护改造提供技术支持,保证管道系统长期安全运行。若管道系统输送介质具有较强的腐蚀性,建议选择内检测方法或根据管道系统的运行记录和流场理论,使用管道外壁漏磁爬行仪器进行重点管段的检测。     

Models and methods of simulating gas pipeline blowdown

Estimation of gas pipeline blowdown time requires the determination of the pressure-time history for the unsteady discharge of gas through a blowdown stack open to the atmosphere. Computational procedures entail various assumptions whose validity and contributions to the accuracy are often not assessed. This paper discusses the computational models and solution methods and further assesses the significance of the various assumptions involved. Volume and pipe models, numerical and analytical methods of solution, effects of stack entrance and friction losses and discharge coefficient are evaluated. The accuracy of a particular model or method of solution is greatly dependent on the fL/D ratio of the pipe section under blowdown. Comparison with field measurements of a straight pipe section and a complicated compressor station yard piping enabled evaluation of the above models.     

An engineering analysis of transient laminar flows in long microchannels

An engineering model of a transient laminar flow from a pressurised vessel through a long microchannel under a condition of a rapid valve opening at a channel outlet is developed. A valve at the channel outlet, which is opening with a given speed, is modelled as a time‐dependent boundary condition. Transient flows are investigated numerically by the method of characteristics. The calculations show that variations of pressure and velocity distributions along the channel over time, caused by a transient flow regime, decrease with a decrease in the channel diameter and the channel length, an increase in the time of valve opening and an increase in the fluid viscosity. © 2012 Canadian Society for Chemical Engineering     

Separation of liquid from vapour upon pressure relief

When a chemical reactor is depressurized or pressure in a vessel, filled with saturated liquid, has to be decreased, generally both vapour and liquid flow out through the relief valve. Since chemical reactors are usually operated with toxic and explosive fluids, the discharged liquid which vaporizes on the ground around the vessel may reach dangerous concentrations, causing explosions or accidents with the poisonous gas. During a research project, some fundamentals were developed for the design of separation systems which separate liquid from vapour and store it in a receiver. The requirement for a separation efficiency of a least 80% is related to the condition that the separated liquid should flow back into the reactor still during the pressure relief phase. For safety reasons, both separation and re-storage are to be carried out without the supply of external energy. Theoretical and experimental investigations of pressure distribution within the piping to the relief valve and in an integrated separator show that re-storage of the separated liquid in the vessel can be achieved under certain flow conditions. Therefore, the separator must be integrated in the pipe at a certain height above the vessel, so that the hydrostatic pressure of the separated liquid, corresponding to the difference in height, is sufficient to lead it back through another pipe against the internal pressure of the vessel. First, several separators were tested with air-water mixtures. A swirl separator and a reversing separator have been developed to such an extent that they appear suitable for the set task. Experimental results with air-water mixtures and refrigerant R12 upon pressure relief show separation efficiencies of between 90 and 100% at low pressure drops within the whole operating range. As an alternative to separation outside the vessel, a rotary separator was also developed which is fixed to the outlet opening in the vessel. A centrifugal field is produced by the separator rotor and the heavier liquid is largely separated from the vapour so that only drops in the range < 100 μm flow together with the vapour towards the central standpipe. The outflowing vapour leaves the separator via 4 tangentially arranged nozzles, under critical conditions. The vapour flow momentum drives the separator rotor. The arrangement was developed and tested during various series of experiments, under conditions or pressure relief with refrigerant R12. So far, separation efficiencies between 60 and 95% have been achieved at stirring speeds of up to 2500 min^?1.     

浅谈安全阀在石油化工及管道上的安装设置

介绍了安全阀的种类及其选用要求,并总结了在石油化工管道设计中,安全阀的一些安装设置经验。     

净饮机高温灭菌电磁阀的设计与消毒效果

目前,净饮机的水质卫生安全正日益受到消费者的关注和重视,市场上主流销售的净饮机,出水嘴一般不带有灭菌或抑菌功能,会对末端出水造成二次污染,导致菌落总数超标。文中利用高温蒸气灭菌原理设计出了一款高温灭菌功能的电磁阀,能实现灭菌后的出水无二次污染;设置了不同的温度和时间进行消毒效果试验,得出在96℃下杀菌40 s后杀菌率可达100%。该设计可应用于净饮机出水结构,解决其末端出水细菌滋生引起的二次污染问题,满足人们日益提高的健康要求。     

带钢保护气氛循环喷射冷却热工过程的数值模拟

对带钢保护气氛循环喷射冷却热工过程建立了一维非稳态传热模型,采用有限差分计算方法计算了带钢的温度场,确定了带钢在不同厚度、初始温度及运行速度下所需的综合换热系数,考察了喷箱的结构参数和循环冷却介质的物性参数对带钢出口温度的影响。结果表明,不同厚度的带钢在满足性能要求及安全的条件下,存在最大运行速度,厚度超过3 mm的带钢的断面温差对带钢性能的影响不能忽略;带钢出口温度会随带钢至喷孔板距离(?)与喷孔直径(D)的比值增大而增大,但增大速率随?/D增加逐渐变小。喷孔间距(?n)与喷孔直径的比值存在最佳范围,且与?有关,因此在实际设计喷箱结构时,不仅需考虑?n/D的最佳值,还需结合?综合考虑;冷却介质(H2+N2)的温度每升高10℃,带钢出口温度增加约3℃。带钢出口温度随冷却介质中氢气含量及流速增加而减小,但减小速率随二者增加而逐渐减小。现场应用结果表明,带钢出口温度的模拟值与实测值吻合较好,误差约为3.4%,满足应用要求。     

大型蒸汽管网系统放空阀、安全阀的设计选型

以某大型化工项目蒸汽管网系统的设计为实例,重点介绍了设计选型时对放空阀放空量和安全阀容量的选择要领、选取原则以及放空阀、安全阀开启压力值的确定方式.     

Experimental Characterization of a Flow‐through Pulsation Damper Regarding Pressure Pulsations and Vibrations

Pressure attenuators, especially side branch bladder‐type accumulators, for suppression of pressure pulsations in industrial fluid applications are not suitable for higher‐pressure pulsation frequencies, e.g., with centrifugal pumps. Accumulators of the flow‐through‐type promise a faster response time and thus a wider application range. The damping performance of a flow‐through pressure accumulator with respect to fluid pressure pulsations and the resulting structure‐borne noise was investigated. The influence of varying pulsation frequencies, damper precharge pressure, and damping effect throughout the piping system was evaluated. Experiments were performed in an industrial‐scale closed‐loop test facility, with both pressure pulsations and piping vibrations in the focus. The damper, characterized by means of high‐speed video analysis, proved to be capable of damping effectively the pressure pulsations and piping vibrations induced by a centrifugal pump.     

利用气水联合顶吹法进行碳钢管道试压和吹扫方法

碳钢管道在焊接安装过程中,管内经常残存有铁屑、铁锈、焊渣、砂土等杂物,这些杂物的存在不仅会影响生产原料的成份,也会使产品受到污染而影响其品质,并会损坏输送物料的机泵或堵塞设备,给工厂的正常生产带来诸多困扰,所以,管道投入使用前,必须将管道内的杂物清理干净。根据作者在管道试压和吹扫中的经验,介绍一种使用气水联合顶吹方式对碳钢管道进行试压和吹扫的方法。     

Influence of Geometry Structures on the Transfer and Flow Characteristics of Membrane Modules

The effects of different inlet/outlet features and helical structures on the flow pattern and transfer performance of membrane modules were investigated with both three‐dimensional computational fluid dynamics and experimental methods. In a circular flat membrane module, two types of inlet/outlet with single‐port or three‐port configuration were used to evaluate the influence of small differences in the opening area structure of the inlet/outlet on the flow patterns. Although the transfer regions differ, large flow swirls appear in both systems, leading to stagnation regions and causing significant back‐mixing. To alleviate the swirls and improve the flow pattern, a helix clapboard was used to separate the membrane feed channel as spiral channel. Both the numerical and experimental results indicate that the helical structure can greatly enhance the transfer performance and increase the permeation rate while the increment in energy consumption is very small.     

塔底强制循环泵入口管道防振设计

130kt／a丙烯酸及酯装置分馏塔塔底物料出口至泵入口的管线振动,管内流体的频率和管道结构的固有频率相近是产生振动的原因。提高管道结构的固有频率,使管内流体的频率和管道结构的固有频率错开,可避免管道振动。设计了调整管道元件分布和增加减振系统两种方案,比较确定更加合理的方案。选用增加减振系统方案,方案实施后,管线没有发生振动现象。     

流量控制方式对离心泵停留时间分布的影响

采用脉冲示踪法研究离心泵的停留时间分布(RTD),将离心泵与等径等体积空管对比,定性描述了离心泵的返混特征,考察了泵前阀控、泵后阀控、转速控制对RTD的影响. 结果表明,RTD曲线呈单峰分布,泵内有死区存在,返混大于等径等体积空管,无因次方差为0.39~0.61;离心泵的返混程度既不靠近平推流,也不靠近全混流,受流量影响显著,随流量增大,返混显著减小. 3种流量控制方式对离心泵返混有一定影响,转速控制的返混情况明显大于2种阀控方式,2种阀控方式的影响较接近;随流量减小,流量控制方式引起的RTD差异更显著,3种方式的无因次方差的最大相对偏差达13.6%.     

水平式安装金属管浮子流量计的仿真与实验研究

通过对适合安装于水平管道的特殊结构的金属管浮子流量计三维湍流流场的数值仿真及实验研究提出一种基于计算流体力学的流量传感器设计方法。流场仿真所需的模型采用GAMBIT来建立,通过FLUNT软件进行仿真,仿真过程中利用受力平衡控制计算精度。数值仿真结果和实验结果比较当浮子受力平衡度误差为9. 5%时,流量误差为0. 944%,证实了仿真结果的准确性,同时利用流场仿真信息对流量传感器模型做了进一步的优化。