某锅炉减温器水管失效原因分析及预防对策

分析了某锅炉减温器出水管轴向弯曲和进水管横向开裂的原因,进行了现场调查、宏观检测、理化检验分析和应力计算。分析结果表明,进出水管与减温器集箱内部构件连接不合理、焊接处应力过高以及腐蚀疲劳是导致减温器水管失效的主要原因。此外,还就失效原因提出了相应的预防对策。     

35t/h炉面式减温器冷却水管裂纹原因浅析

对面式减温器冷却水管产生裂纹原因的分析表明，由于水质含氧和Cl^-离子过高，造成腐蚀，同时由于操作不当，产生温变应力，致使冷却水管腐蚀疲劳产生裂纹。     

锅炉过热蒸汽二级减温器损坏分析与处理

针对锅炉过热蒸汽二级减温器损坏情况,分析减温器喷管断裂及减温器筒体、管座产生裂纹的原因,采取了临时处理措施,并对设备进行改造,实现了优化。     

锅炉减温器喷头缺陷检验及原因分析

减温器是电站锅炉的重要组成部分,关系到锅炉能否安全可靠的运行,提供符合要求的过饱和蒸气,使得汽轮机能够达到理想的工作状态,然而由于减温器在制造和运行过程中的许多不确定因素,使得减温器喷头可能产生裂纹等缺陷,最终将导致减温器的减温水直接冲刷减温器联箱简体,这对锅炉的安全运行造成极大的威胁。本文主要分析了锅炉减温器喷头出现缺陷的原因,采用无损检测方法分析了减温器喷头潜在的危险因子。     

减温器管座焊缝裂纹的成因分析

对中压锅炉面式减温器管座焊缝裂纹产生的原因进行分析     

锅炉减温器故障引发的事故原因及处理

减温器是锅炉中的一项重要构成部分,其性能会对锅炉的运行可靠性与安全性造成直接影响。但是,从实际情况来看,锅炉中采用的减温器的制作和运行会受到不同因素影响,这可能会导致减温器在应用期间遭受破坏,进而对锅炉运行的安全性造成阶段威胁,甚至会引发安全事故。下面,针对锅炉减温器故障引发的事故原因及处理进行分析,希望文中内容对相关工作人员以及行业的发展可以有所帮助。     

锅炉减温器裂纹原因分析及改进措施

找出了锅炉喷水减温器产生裂纹的主要原因是结构设计和内套筒选材存在缺陷。对套筒和喷嘴的支撑结构、套筒与联箱的连接方式和套筒材料进行了改进，通过改进，减温器运行正常，达到了预期的效果。     

锅炉减温器构件开裂分析

本文对某锅炉减温器进出水管两个部位的开裂进行了检测分析,认为开裂的原因是进出水管与减温器集箱内部构件焊接形成近乎刚性的结构,因升温产生的膨胀受到约束,过大的温差应力导致产生过量的变形及开裂。     

新型文丘里式喷水减温器的入口型线设计

根据喷水减温器的工作原理,结合几种减温器的典型结构形式,设计了一种新型文丘里式喷水减温器。该减温器可容纳大范围的蒸汽流量,提高了减温效率。同时蒸汽经过喷嘴处会产生卡门涡街,增加了水粒在蒸汽中的停留时间,使气液两相换热更加充分,减小吸收距离,节约管材成本。利用文丘里流量测量计相似原理对减温器的入口型线做了理论设计研究,通过探讨和分析,论证了新型文丘里式喷水减温器的合理性和可行性。     

笛型管式减温器通用化设计思路

目前公司采用的笛型减温器,结构数据多样,生产组织困难,用户频繁反馈减温器出现泄漏,为提高生产效率,提升产品质量,现就笛型管式减温器通用化设计进行探讨。     

Experimental investigation of gas-liquid flow in a vertical venturi installed downstream of a horizontal blind tee flow conditioner and the flow regime transition

A venturi device is commonly used as an integral part of a multiphase flowmeter (MPFM) in real-time oil-gas production monitoring. Partial flow mixing is required by installing the venturi device vertically downstream of a blind tee pipework that conditions the incoming horizontal gas-liquid flow (for an accurate determination of individual phase fraction and flow rate). To study the flow-mixing effect of the blind tee, high-speed video flow visualization of gas-liquid flows has been performed at blind tee and venturi sections by using a purpose-built transparent test rig over a wide range of superficial liquid velocities (0.3–2.4 m/s) and gas volume fractions (10–95%). There is little ‘homogenization’ effect of the blind tee on the incoming intermittent horizontal flow regimes across the tested flow conditions, with the flow remaining intermittent but becoming more axis-symmetric and predictable in the venturi measurement section. A horizontal (blind tee) to vertical (venturi) flow-pattern transition map is proposed based on gas and liquid mass fluxes (weighted by the Baker parameters). Flow patterns can be identified from the mean and variance of a fast electrical capacitance holdup measured at the venturi throat.     

水力空化装置文丘里管的模拟优化

基于FLUENT软件．采用标准的κ-ε模型和空化泡动力学模型对三种不同几何形状的文丘里管中的空化流场进行了数值模拟，井将计算结果与实验结果进行了比较．计算结果表明，理论计算的汽含率分布与实验拍摄的汽含率分布是相似的。文丘里管的结构对空化效应有着重要的影响．从而为文丘里管的优化设计提供了依据。     

Flow measurement and instrumentation flow control characteristics of throttling venturi valve with adjustable area

In this study, a throttling venturi valve with adjustable area was designed to control the thrust of a monopropellant thruster using hydrogen peroxide. The flow rate control characteristics of the throttling venturi valve were investigated based on the pintle stroke and upstream pressure of the venturi. Three kinds of experiments were conducted: pressure and flow rate measurement according to pintle stroke and venturi upstream pressure, determination of critical pressure ratios under various conditions, flow rate control performance through open-loop control and feedback control of an actuator. The pressures were measured at the upstream, throat, and downstream of the venturi. It was observed that the flow rate changed in proportion to the stroke and upstream pressure. Below a stroke of 10 mm, the critical pressure ratio gradually decreased as the stroke and upstream decreased. However, above a stroke of 10 mm, the critical pressure ratio converged to a value between 0.7 and 0.8 regardless of the upstream pressure. The results of automatic flow rate control tests using open-loop control and feedback control showed that the measured flow rate satisfactorily followed the target flow rate profile.     

Application of small size cavitating venturi as flow controller and flow meter

The cavitating venturi is using to provide constant mass flow rate of liquid which is passing through a passage, independent of downstream pressure changes. The flow rate is a function of the upstream pressure, the throat area, the density and saturation pressure of the liquid. An experimental setup with capability of supplying water flow rate and constant upstream pressure was designed and manufactured. Three cavitating venturis with throat diameter of 5, 2.5, and 1 mm were designed and built to investigate the effect of venturi size on its mass flow rate. Three different sets of experiments were conducted to investigate the performance of the venturis. In the experiments, the mass flow rates were examined under different downstream and upstream pressure conditions and time varying downstream pressure. The results show for the ratio of downstream pressure to upstream pressure less than 0.8, the mass flow rate is constant and independent of the downstream pressure. Whenever the pressure ratio exceeds 0.8, the venturi acts like an orifice. This pressure ratio has been predicted analytically to highlight the affecting parameters, mainly the geometry of the venturi and viscous losses. It is found that the venturi size has no effect on its expecting function to keep mass flow rate constant. Also, it is shown that by applying a discharge coefficient and using only upstream pressure, the cavitating venturi can be used as a flowmeter with a high degree of accuracy in a wide range of mass flow rate.     

基于Profibus-DP的文丘里流量计设计

将Profibus现场总线技术应用于文丘里流量计,提出了一种具有Profibus-DP现场总线总线功能的智能文丘里流量计的硬件和软件实现方法。     

An investigation of a cavitating venturi flow control feature in a cryogenic propellant delivery system

This study details the design and performance characterization for a cryogenic cavitating venturi. This flow control system is intended for mass flow regulation of cryogenic propellants, such as liquid oxygen and liquid methane, in reaction control propulsion systems. Through in situ flow tests, the discharge coefficient for the venturi was calculated and utilized to determine the mass flow rate for specified inlet pressures of the propellants. The test results revealed that the cavitating venturi indeed performed as a flow rate control feature in both liquid water and LCH₄ flow under a steady state operating within pressure ratios below 0.69.     

Application of variable area cavitating venturi as a dynamic flow controller

The variable area cavitating venturi is an effective means to throttle the mass flow rate of liquid. The mass flow rate is a function of the upstream pressure, the pintle stroke, the density and saturation pressure of the liquid, independent of the downstream pressure. In this paper, a variable area cavitating venturi is designed and four different sets of experiments are conducted to investigate the performance of the variable area cavitating venturi. In these experiments, the mass flow rates are examined under different pintle positions, upstream pressures, downstream pressures and dynamic motions of the pintle. The experimental results indicate that the mass flow rate is independent of the downstream pressure when the ratio of the downstream pressure to upstream pressure is less than 0.8. The mass flow rate is almost linearly dependent on the pintle stroke for a constant upstream pressure. The discharge coefficient is a function of the pintle stroke, whereas the upstream and downstream pressures have rare influence on the discharge coefficient. The variable area cavitating venturi can control and measure the mass flow rate dynamically by determining the pintle stroke and the upstream pressure.     

A CFD study of wet gas metering over-reading model under high pressure

The venturi flow meter is increasingly being preferred in multiphase flow measurement because of its shorter upstream and downstream straight sections, less influenced by the flow pattern and relatively small pressure loss. However, when the venturi is used for wet gas measurement, the over-reading phenomenon occurs due to the presence of a small amount of liquid. Many scholars have established over-reading models to correct the measured values of wet gas. Regrettably, the applicability of these over-reading models under actual high pressure operating conditions has not been verified. Therefore, this review focuses on numerical simulation of the flow of wet gas in the venturi tube under high pressure conditions (11MPa/13MPa/15 MPa). The discrete phase model (DPM) and the standard k-ε model was employed in this review. The simulations results reveals the flow characteristics of wet gas in venturi tube, which includes the flow field distributions, droplet concentration distributions and wall pressure profile distributions, and indicates that the over-reading values increases with the increase of Lockhart-Martinelli parameters and gas volume flow rate, but decreases with the increase of pressure. Moreover, the ISO model has the best performance under high pressure conditions.     

A study of cavitation bubble collapse pressures and erosion part 3: the results in a venturi facility

Cavitation erosion generated in a venturi facility was studied by comparing the erosion loss with the distributions of cavitation bubble collapse pressures (impact loads). The erosion process in the venturi tests is similar to that in the vibratory tests, although its progression is very slow. That is, the surface first deforms and fractures as a result of fatigue with repeated bubble collapse pressures below the threshold pressure needed to form a pit impulsively. By comparing the distributions of impact loads measured using our method with the hypothetical stress-number of cycles curves for fatigue, it is found that the incubation period and the volume loss rate during the stable period follow Miner's law regardless of the venturi, vibratory and cavitation conditions and materials. Therefore we found that we are able to estimate cavitation damage in a flowing system in the same way as damage in the vibratory tests from Miner's law although the distributions of cavitation bubble collapse pressures are markedly different.     

内文丘里管流量计

本文介绍了一种集经典文丘里管、环形孔板和耐磨孔板计量性能成于一体的新型差压装置－－内文丘里管，对这种差压装置的结构、测量原理、技术性能、适用范围、可膨胀性系数的确定方法以及内文丘里管优异计量性能形成的机理作了简要的论述，同时还展望了该种差压装置有望取代孔板等传统差压装置的广泛应用与良好发展前景。