Design and Experimental Analyses of Small-flow High-head Centrifugal-vortex Pump for Gas-Liquid Two-phase Mixture

The design method of small-flow high-head centrifugal-vortex pump was presented. This pump, configured with inducer, complex-centrifugal impeller and open-vortex impeller, was put forward to deliver gas-liquid two-phase mixture. An HTB-5/60 type sample pump was developed and tested on a closed-loop test rig. Experimental studies on performance and cavitation tests for gas-liquid two-phase mixture were carried out compared with pure-water experimental results. Also the effect of gas phase on pump was analyzed and discussed. The experimental results show that performance and cavitation characteristics of the sample purnp deteriorates progressively with increasing volume fraction of gas. When the total capacity Qm is between 4.5 m^3·h^-1 and 6 m^3·h^-1 and the gas flow rate qg below 0.66 m^3·h^-1, or qg/Qm is lower than 15%, the characteristic curves are approximately parallel to those in pure water test, but the performance deteriorates sharply until an abrupt flow-cutting at a critical volume fraction of gas. This pump is found suitable for transporting gas-liquid two-phase mixture when working around rated capacity of 5 m^3·h^-1 with qglQm below 15%.

Evaluation of Performance of Thermal and Electrical Hybrid Adsorption Chiller Cycles with Mechanical Booster Pumps

Large amounts of waste heat below 100oC from the industrial sector are re-leased into the atmosphere. It has been suggested that energy system efficiency can be increased with adsorption chillers. However, the cooling power and coefficient of performance (COP) of conventional adsorption chillers significantly decrease with the desorption temperature. In this paper, we proposed a mechanical booster pump (MBP)-assisted adsorption chiller cycle, and evaluated its performances. In the cycle, a MBP was incorporated into a zeolite-water-type adsorption chiller for facilitating water vapor transportation between an adsorber and an evaporator/condenser. We have experimentally studied the effect of the input electrical power of MBP on the performances of adsorption chiller cycle. It has been demonstrated that the heat input achieved by using MBP at the desorption temperature of 50oC was 1.6 times higher than that of without MBP at the desorption temperature of 60oC. And the increase of pump power was found to be effective in increasing the heat input. Therefore, it was confirmed that the operation range of desorption temperature, which can be generated by using the waste heat, was extended and the cooling power was increased directly by using MBP.

A Numerical Study on the Effect of the Backflow Hole Position on the Performances of a Self-Priming Pump

A self-priming pump is a centrifugal pump that has the ability to prime itself. Typically, its performance dependson the configuration of its reflux hole. In this study, the ANSYS FLUENT software is used to investigate the effectsof three different radial positions of the reflux hole on gas-liquid two-phase distribution, pressure pulsation, andimp during self-priming. The research results indicate that: (1) The effective channel size for the reflux liquid toenter the volute varies depending on the location of the reflux hole. The effect of the impeller rotation on thereflux liquid becomes more obvious as the setting distance of the reflux aperture decreases. (2) The position ofthe reflux hole significantly affects the gas phase mass fraction inside the impeller, resulting in a significant reductionin the time it takes for the mass fraction to exceed 80%. (3) The position of the reflux hole significantly affectsthe average pressure on each monitoring surface. (4) Placing the reflux hole at a excessively distant radial distancecan result in an excessive vertical component. (5) The self-priming performance of the pump can be improved tosome extent by placing the return hole at a small radial distance.

Performance Prediction of the Helico-axial Multiphase Pump

A modified one-dimensional model is developed for prediction of multiphase pump performance. Taken into account in the model are the gas compressibility, the slip speed gap between two phases and the flow cross-sectional depth gradient in the flow line. By using this model, we can select appropriate geometrical parameters of the impellers and guide vanes, and thus higher-pressure boost is obtained but phase separation does not occur. Accordingly, the design method can be optimized. The drag coefficients are analyzed for different flows. Results predicted by the modified model are compared with a series of experimental data and found in good agreement. This model provides a convenient and economical tool for engineering design over a traditional one.

Numerical simulation on centrifugal pump compressible flow field with different gas volume fractions

In order to study the influence of gas-liquid two-phase flow on the performance and internal flow field of a centrifugal pump,the steady three-dimensional flow with different gas volume fractions was simulated by applying the Reynolds-average N-S equation and mixture gas-liquid two-phase flow model,and the compressibility of gas was taken into consideration in the simulation. Then the centrifugal pump characteristic and the gas distribution law in different gas volume fractions were analyzed. The computational results show that gas volume fraction has a certain influence on the performance of the centrifugal pump,and the efficiency and head of the pump are on the decline with the increase of it.Static pressure in the impeller increases in the radial direction,but the pressure gradient in the flow direction is different under the different gas volume fractions. The gas volume is distributed mainly in the ipsilateral direction of impeller back shroud in the flow channel of the volute. On the suction side of the blade inlet there is an obvious low-pressure area,which causes bubbles agglutination and higher gas volume fraction. With the gas entering passage flow,gas volume fraction in the suction decreases and the pressure surface rises gradually. Higher gas volume fraction causes air blocking phenomenon in the flow passage and the discharge capacity reduces. The increase of gas volume makes the turbulent motion within the impeller more and more intense,which leads to more and more energy loss.

An Innovative Organic Rankine Cycle with Gas-liquid Injector for Pressurization

The organic Rankine cycle （ORC） is an effective way to recycle low temperature exhaust heat but pump for the ORC has several disadvantages such as great difficulty in manufacturing, easily-invited cavitations, low efficiency and high cost. Gas-liquid two-phase injector is a device without moving parts, in which steam is used to drive cold liquid from a pressure lower than the primary steam to a pressure higher than the primary steam. In this paper, the mechanical circulation pump was replaced with a gas-liquid injector. The effect of the evaporate temperature for the system was studied with the organic fluid R123. While this novel ORC can not only improves the energy utilization, but also be suitable for some occasions without power.

一种用于微能量收集的升压电荷泵设计

开关电容直流-直流(Direct Current-Direct Current,DC-DC)变换器是电源管理系统中极其重要的一部分,升压电荷泵是其中的一个分支。在微能量收集的应用场景中,升压电荷泵的研究热点是实现低的泄漏电流和低的阈值电压损耗。多数升压电荷泵设计为了减少阈值电压损耗和电荷共享等非理想效应,使泄漏电流增大,或结构变得复杂,导致面积增大,不适用于微能量收集场景。Dickson电荷泵是早期的电荷泵结构,其结构简单实用,但较大的阈值电压损耗是其最大的缺点。为此,本文基于Dickson电荷泵进行分析,采用TSMC 250 nm工艺,使用中等阈值电压(Medium Threshold Voltage,MVT)型金属氧化物半导体场效应晶体管(Metal-Oxide-Semiconductor Field-Effect Transistor,MOS)代替二极管,降低阈值电压损耗,再利用体源二极管偏置技术,进一步降低阈值电压损耗。本文利用Positive MOS(PMOS)管与Negative MOS(NMOS)管级联的形式,减少泄漏电流,且NMOS管采用深N阱工艺,避免加入辅助电路。仿真结果表明,本文的升压电荷泵结构设计具有较好的性能表现,达到了设计要求。

高速运行齿轮泵的吸油空化与抑制

为揭示齿轮泵高转速运行时的空化发展规律,对装载机用大功率双联齿轮泵的吸油特性展开研究。通过全流域仿真模拟及试验,分析了转速、吸油压力对双联齿轮泵空化现象及输出流量特性的影响。结果表明,双联齿轮泵发生明显吸油空化的临界转速为2400 r/min,当转速大于2400 r/min后,泵内的气体含量骤增,严重影响输出流量的连续性和稳定性;双联齿轮泵的临界吸油压力为0.19 MPa,继续增大吸油口压力会增大泵出口的流量脉动,与入口为0.1 MPa相比,吸油压力为0.19 MPa时齿轮副1和齿轮副2的气体体积分数分别降低0.059和0.067,有效流量分别增大7.96%和9.24%。通过增压装置增加泵的入口压力,对齿轮泵空化的抑制以及有效流量的提升有明显的改善作用,具有工程实际意义。

基于地面大口径钻孔抽排的老空水害防治技术

为了安全高效治理矿井老空水害,在井下不具备疏放老空水的条件下,采用了地面大口径钻孔和接力抽排水的方案对老空水害进行治理。选取位于老空积水区最低点的水仓作为地面钻孔的终孔位置,施工三级变径的大口径钻孔。下设的一级套管对钻孔在松散层中进行了固井,二级套管对老空区及采动破坏范围上覆含水层进行了隔离,采用无线随钻测斜和定向钻进技术,保障了大口径钻孔的准确透巷。钻孔中下设潜水泵将老空水抽至地面,然后采用管道增压泵将老空水接力排至矿井水处理厂,实现了老空水抽排过程中不落地。通过对抽排水量和老空水位的观测,验证了基于地面大口径钻孔和接力抽排老空水的效果。结果表明:采用地面大口径钻孔和井下潜水泵联合地面增压泵接力抽排关闭矿井老空水效果较好,具有安全性和可靠性高、排水和水处理费用低等特点。

核电厂汽动辅助给水泵转速调节系统鲁棒性提升研究

某核电厂二期工程采用了国产化核级汽动辅助给水泵,调试过程中屡次发生给水泵启动时间超标、启动后转速无法稳定、启动过程中超速跳闸事件。对汽动辅助给水泵调速系统进行了建模及分析,研究了电子调速器、电气转换器、气动定位器、气动增速器等部件的工作特性,分析并通过试验比较了不同流量系数的气动增速器对气动执行机构动态响应特性的影响。采用更换小流量系数气动增速器和调速器参数优化的方法,提升了汽动辅助给水泵调速系统的鲁棒性,解决了给水泵启动失败的问题。该研究的过程和成果可作为国产核级汽动辅助给水泵调速系统的设计参考,对于气动执行机构有关的控制系统参数优化、鲁棒性提升等其他同类问题的处理也有重要的指导意义。

Examination on behavior of tip leakage flow in a three-stage gas-liquid two-phase flow pump

Tip leakage flow(TLF)trajectory in a pump with gas entrainment is investigated via visualization experiments and numerical simulations.Starting position of tip leakage vortex(TLV)is determined accurately by numerical simulation.Under high liquid flow rate(Q_(l))and high inlet gas volume fraction(IGVF)conditions,TLF flows from suction surface to pressure surface near the leading edge of blade,and the direction of TLF gradually changes along the chord which flows from pressure surface to suction surface near the tailing edge.The angle between TLF and blade mean camberline increases progressively as either Q_(l)or IGVF decreases,and starting position of TLV moves towards leading edge direction.As Q_(l)or IGVF decreases,value of vorticity increases and high vorticity region moves towards leading edge.The entropy production rate at blade tip clearance is high,and entropy diffuses from pressure surface to suction surface due to jet flow in blade tip clearance.The greater the amount of accumulated gas there is,the greater the amount of entropy in the area.In addition,when gas is entrained in pump,there are many low frequency fluctuations generated in blade tip clearance.

沉井与基坑支护结合法在某增压泵站中的应用

与常规泵站不同,增压泵站具有单体较多、开挖深度不一及平面形状不规则等特点,采用沉井法或基坑支护法单独实施时,会产生施工方式不合理、工程成本较高或工期较长等问题。本文结合某增压泵站工程案例,从安全、经济、便捷等角度对沉井法、基坑支护法及沉井+基坑支护法等方案进行对比分析,提出了一种沉井与基坑支护相结合的结构形式。该结构形式不仅具有沉井结构工程成本低、施工便捷的优势,还具有基坑支护结构形式灵活、便于保护周边环境的优点;同时也为类似工程项目的结构选型提供了一种新的思路。

自适应回路在压裂泵流体脉动抑制中的应用

针对液压驱动式压裂泵流体脉动问题,分析了其脉动机理,通过对基于蓄能器-增压缸组合的传统脉动抑制回路进行理论研究,提出了一种基于蓄能器-增压缸组合的自适应脉动抑制方法,并对自适应脉动抑制特性进行理论分析,研究了系统稳态压力等参数的变化对其脉动抑制效果的影响。利用MATLAB/Simulink软件建立脉动抑制回路数学模型,对两种抑制方法进行对比仿真研究,结果表明:相比较基于蓄能器-增压缸组合的脉动抑制方法,自适应方法具有更好优的抑制效果,其脉动压力幅值是传统方法的45%~86%左右,且具有一定的自适应性、良好的稳定性和灵活性。

超高压柱塞增压泵泛塞式组合密封的密封性能分析

为研究超高压柱塞增压泵泛塞式组合密封的密封性能,基于橡胶材料的Mooney-Rivlin本构关系,在Ansys Workbench中建立其组合密封的二维轴对称有限元模型,研究介质压力、预压缩量和摩擦因数对组合密封的密封性能影响,并对组合密封中O形圈的摩擦应力进行分析。结果表明:组合密封中的PTFE密封环及O形圈最大von Mises应力随着介质压力增大而增大,且内行程时两者高应力区域随着介质压力变化发生移动;介质压力一定时,预压缩量对外行程时的组合密封最大von Mises应力影响较大,von Mises应力随着预压缩量增加而增大;O形圈的摩擦因数对其摩擦应力影响最大,O形圈的摩擦应力随着其摩擦因数的增大而增大,在保证密封良好的前提下,降低预压缩量和摩擦因数,有利于延长超高压柱塞增压泵组合密封的工作寿命。

实时三维超声对LVNC患者左心房功能的评估价值

目的探讨实时三维超声对左心室心肌致密化不全(LVNC)患者左心房管道功能、助力泵功能、储存功能的诊断价值。方法选取180例有LVNC超声表现的患者(实验组),另外再选取180例年龄相符的健康者(对照组)。采用Philips iE33彩色多普勒超声诊断仪采集二维左心房测量值和三维左心尖四腔心切面full-volume图像,并应用Qlab9.1工作站的3DQAdvanced工具进行脱机处理。结果对照组和实验组的Ve/Va、左心室射血分数、LVEDD、室壁厚度、年龄均差异无统计学意义(P>0.05)。实验组的LAFV/BSA、左心房扩张指数、LAEF均显著大于对照组,差异有统计学意义(P<0.05)。实验组和对照组LAPASV/BSA、LACV/BSA、LAPEI均差异无统计学意义(P>0.05)。实验组和对照组LAASV/BSA分别为(8.73±3.92)ml/m^(2)和(5.53±3.92)ml/m^(2),LAAEI分别为(51.27±9.86)和(36.28±12.49),均差异无统计学意义(P>0.05)。实验组LAASV/BSA、LAAEI显著高于对照组,差异有统计学意义(P<0.05)。实验组和对照组左心房最大充盈容积/BSA分别为(22.58±8.64)ml/m^(2)和(18.06±4.76)ml/m^(2),实验组的左心房最大充盈容积相较对照组更高。Bland-Altman分析图显示LAVmax/max测量的检查者内和检查者间的一致性符合要求。结论实时三维超声能有效评估LVNC患者的左心房管道功能、助力泵功能、储存功能。

VIM真空感应炉真空度修复分析

以太钢技术中心基础研究所的德国ALD真空感应炉作为研究对象,其连续服役十余年,大量的冶炼试验对真空炉的抽真空系统造成了严重的影响,工作真空度不断降低,导致钢锭质量下降。通过分析真空炉抽真空泵级系统原理,提出将真空泵级系统进行拆解维护修复方案。经过实践证明,该修复方案切实可行,能够大幅度提高真空感应炉的工作真空度。

野外单井注水增压泵失效分析及改进

野外单井增压泵是解决注水井注入压力和注入水量未达到要求的一种有效方式。增压泵经常存在因盘根刺导致的增压泵漏失现象,通过现场维修并分析认为增压泵失效的原因是柱塞表面电镀铬涂层剥落,碎屑随柱塞高速运转、划伤盘根,使盘根不具备密封性,导致增压泵漏失。对增压泵的柱塞涂层进行改进,采用激光熔覆技术在柱塞表面涂敷一层哈氏合金C22涂层,经过3个月的观察,新涂层表现出很好的耐蚀性能,涂层表面没有出现剥落痕迹,盘根的密封性得以保证,柱塞的使用期限延长3倍以上,同时为野外单井增压泵带来一定性能上的增益。

大型智慧化给水加压泵站工艺设计

以广州市某加压泵站为例,详细阐述大型给水加压泵站的工艺设计。该加压泵站为广州市北部水厂二期扩建工程配建的中途加压泵站,设计规模为40×10^(4)m^(3)/d,采取了“直抽+库抽”相结合的加压方式。水泵选用卧式中开双吸离心泵,为适应不同工况的运行要求,采用“大泵+小泵”“工频+变频”的泵组配置方案。泵站内建设1×10^(4)m^(3)清水池保证供水稳定性,并设置一体化加氯泵组保证供水水质。

三洲榕南干渠应急引水加压泵站建设实践

随着全球气候变化的影响日益显著,各地的水资源状况也在不断发生变化,干旱是其中最为突出的问题之一。加压泵站的建设可以有效提高水资源利用效率,解决水资源在空间和时间上的分布不均,提高水资源的利用效率和保护效果在抗旱工作中发挥着至关重要的作用。以榕南干渠输水管线建设工程为背景,探讨在引水抗旱下,如何进行干渠输水管线的建设,结合工程背景进行了必要性分析,提出了泵站布置方案如泵站选址、型式设计,加压泵站建设控制要点等等,该工程项目的建设旨在优化水资源配置,保障城市发展,为周边地区的农业生产和生活用水提供稳定可靠的水源,为抗旱工作的顺利进行做出贡献。

某深水气田平台放空气回收技术的研究与应用

南海某深水气田平台降压开采后,高压放空气20000 m^(3)/d、低压放空气5000 m^(3)/d因无法进入湿气压缩机入口外输而被火炬系统燃烧;项目的主要挑战在于低压放空气的回收,进口压力从近乎于0 MPa提升到2.5 MPa,新设备的组合选型和现场调试是项目的难点。为解决以上问题,通过研究和制定高低压放空气回收方案,并进行方案优选,最终采用新增2台凝析油增压泵提升系统压力让气相重新进入到湿气压缩机的高压放空气回收方案,以及组合选型确定为新增设备液环压缩机和射流器对低压气进行回收的低压放空气回收方案。项目实施后,成功完成了预期回收目标,经济效益和社会效益良好;试运行过程中,通过逐一解决低压放空气回收新增设备的各种问题,保证了低压放空气回收组合设备的稳定运行,增加了类似天然气平台的放空气回收再利用的经验积累,有一定的借鉴和指导意义。