并联清水泵实际运行工作点的确定

用简单"横加法"所确定的并联水泵工作点往往和泵的实际运行工作点存在一定误差,其原因是忽略了分支管路的影响,本文在考虑这一因素基础上给出了并联水泵实际运行工作点的确定方法,可供实际选泵时参考。     

注水泵并联运行的特性

油田注水泵站配置多台泵,根据注水量需求,调整开泵台数。论文根据注水泵并联运行时的特性曲线变化的原理,分析了并联泵存在排量差异、压头差异、转速差异等情况下的总特性曲线,探讨了几种并联方式下的系统效率及并联运行优化的方法。     

注水泵并联运行的特性

油田注水泵站配置多台泵,根据注水量需求,调整开泵台数。论文根据注水泵并联运行时的特性曲线变化的原理,分析了并联泵存在排量差异、压头差异、转速差异等情况下的总特性曲线,探讨了几种并联方式下的系统效率及并联运行优化的方法。     

注水泵并联运行的特性

油田注水泵站配置多台泵,根据注水量需求,调整开泵台数。论文根据注水泵并联运行时的特性曲线变化的原理,分析了并联泵存在排量差异、压头差异、转速差异等情况下的总特性曲线,探讨了几种并联方式下的系统效率及并联运行优化的方法。     

注水泵并联运行的特性

油田注水泵站配置多台泵,根据注水量需求,调整开泵台数。论文根据注水泵并联运行时的特性曲线变化的原理,分析了并联泵存在排量差异、压头差异、转速差异等情况下的总特性曲线,探讨了几种并联方式下的系统效率及并联运行优化的方法。     

变频调速给水系统水泵选型与运行的优化

从对离心泵特性曲线的分析入手,研究了恒压变量变频调速给水系统水泵选型与运行的优化问题。研究表明只有在水泵选型与运行调度都合理时,调速给水才能达到节能目的;调速泵与不同型号恒速泵并联优于与同型号恒速泵并联;系统运行时设定的工作压力应等于或略大于调速水泵高效区右端点的扬程。     

高压液氨泵并联运行流量脉动分析

通过对往复泵运动规律的分析,给出双泵并联运行累加流量和流量不均匀系数的计算公式,并利用Excel函数编程,对高压液氨泵并联运行累加流量进行模拟,探讨双泵并联运行在不同错相位角和转速下流量不均匀系数的变化规律,总结最佳操作工况,提出峰值分散技术应用的思路。     

BOG-LNG系统联合运行技术研究

综合分析了LNG接收站处理BOG(Boil-off gas)的工艺、运行参数、关键设备、运行模式,对每种工艺及运行方案汇总归纳,使得LNG接收站多变的运行工况充分应用不同的工艺和运行方案,为LNG接收站平稳安全运行提供可靠保障。也使LNG接收站项目的BOG处理工艺有选择,并提供一定的借鉴指导。     

LNG接收站中再冷凝工艺的技术分析及优化

LNG接收站在运行过程中会产生蒸发气(BOG),若不及时处理会造成接收站超压,而不得不放空至火炬燃烧,既浪费能源又污染环境。对于接收站正常操作工况下产生的BOG,通常采用再冷凝的工艺进行处理。介绍了国内对于BOG再冷凝工艺存在的2种设计理念,分析了固定LNG/BOG流量比例的设计模式存在的问题,对于设计理念中不完善部分进行了讨论;同时结合现场实际操作中出现的问题,验证该设计会导致再冷凝器中的液位出现较大波动,影响再冷凝器和整个接收站的稳定运行。对上述设计模式进行了优化,通过改变LNG与BOG流量比值,使再冷凝器内LNG为饱和状态,保证了再冷凝器的稳定运行。     

LNG接收站腐蚀情况分析

我国 LNG接收站大多位于沿海地带,长期处于高湿、高盐雾环境,按照 ISO12944大气腐蚀环境分类属于 C4或 C5-M等级。随着 LNG接收站运营年限延长,其腐蚀问题逐渐凸显。本文介绍了 LNG接收站工艺、用材、运行介质、原有防腐措施等,在此基础上分析了 LNG接收站常见腐蚀问题,并对其原因进行了分析,为 LNG接收站新站防腐设计和运营维护工作提供参考。     

Parallel Operation of Centrifugal Pumps: Effects of Rotational Speed Differences due to Motor Slip

In industrial plants, centrifugal pumps are frequently operated in parallel configuration, not least for redundancy and operational reliability reasons. However, regarding the resulting pressure pulsations and energy consumption, this operation mode has so far not been in the focus of scientific studies. The object of the present article is to clarify the effect of parallel operation with respect to the observable pressure pulsations. Measurements were carried out with two identical centrifugal pumps operating in parallel mode in an industrial‐scale closed‐loop piping system. The results suggest that, regarding both the resulting pressure pulsations and the operating point of each pump, this operation mode is quite sensitive to smallest rotational speed deviations as they may occur due to different motor slip. The results indicate furthermore that, for minimum pressure pulsations, equal power consumptions of the two pumps are crucial, but not necessarily equal rotational speeds.     

给水泵并联运行方式的分析及经济性比较

大型化工企业自带火力发电厂的锅炉给水系统多采用母管制。文章将简述锅炉母管制给水系统的工作特性,并讨论定速泵与定速泵、调速泵与调速泵、调速泵与定速泵并联运行三种方式各自调节的状态、特点及经济性分析。为企业实际的生产运行提供理论依据,并达到安全生产、节约能源的目的。     

Performance of Nozzle/Diffuser Micro‐Pumps Subject to Parallel and Series Combinations

This study numerically examines the performance of micro nozzle/diffuser pumps subject to parallel and series combinations. For a single‐chamber micro nozzle/diffuser micro‐pump, four stages are identified. For dual micro‐pumps in a parallel combination, the flow field in each chamber is symmetrical about the center line of the arrangement. For in‐phase operation, the maximum flowrate is about two times higher than that of the single‐chamber. For micro‐pumps in a series combination, it is found that the overall performance is strongly related to the phase angle. The effective flowrate can be significantly increased, decreased, or even reversed. This indicates that the flowrate can be controlled within a wide span by changing the phase angles. At a phase angle of 90°, an eight‐fold increase of effective flowrate is seen relative to that of a single‐chamber operation. The significant increase of flowrate is attributed to two effects; the first effect is due to the “active valve” effect that increases the efficiency during pump mode. The second influence is attributed to the increased pressure difference that brings in more fluid during supply mode.     

Engineering model for coupling wicks and electroosmotic pumps with proton exchange membrane fuel cells for active water management

We present theoretical and experimental studies of an active water management system for proton exchange membrane (PEM) fuel cells that uses integrated wicks and electroosmotic (EO) pumps. The wicks and EO pumps act in concert to remove problematic excess liquid water from the fuel cell. In a previous paper, we showed that this system increases maximum power density by as much as 60% when operating with low air stoichiometric ratios and a parallel channel flow field. The theoretical model we develop here accounts for several key factors specific to optimizing system performance, including the wick's hydraulic resistance, the variation of water pH, and the EO pump's electrochemical reactions. We use this model to illustrate the favorable scaling of EO pumps with fuel cells for water management. In the experimental portion of this study, we prevent flooding by applying a constant voltage to the EO pump. We experimentally analyze the relationships between applied voltage, pump performance, and fuel cell performance. Further, we identify the minimum applied pump voltage necessary to prevent flooding. This study has wide applicability as it also identifies the relationship between active water removal rate and flooding prevention.     

凝结水泵出力不足的问题排查、分析与处理

离心泵是化工、电力生产中的重要输送设备,凝结水离心泵（凝结水泵）是电厂中的重要辅助设备。某电厂在试运期间,在机组高负荷时,凝结水泵发生汽蚀现象。分析了凝结水泵发生出力不足的原因,并通过对凝结水泵入口蝶阀进行改造,消除了出力不足的设备缺陷,提高了凝结水泵运行的安全性和经济性。     

循环冷却水系统的复合节电方式实践

以并联水泵供水的循环冷却水系统为节电对象,分步实施了水泵叶轮切削,单台水泵变频调速的组合控制方案,优化了水泵的工作点,实现了自动调节的恒压供水,完全消除了泵后闸阀的节流损失,总体节电率达46.8%。     

转子泵的选用(下)

转子泵是一种旋转的容积式泵，特别适用于输送粘性介质。此外和往复泵一样，具有正排量性质，可适用于计量及要求流量不随背压变化的场合。为便于使用者了解转子泵，合理选用泵型，本文系统介绍了转子泵的原理、结构、参数、类型、选用、标准、检验及使用中应注意的问题。     

高压筒袋泵间歇性异常振动的故障诊断与控制

高压筒袋式多级离心泵出现间歇性异常振动,在初步排除泵自身不平衡为主要因素的基础上,通过对两台并联运行的泵进行振动测试对比分析,诊断为齿形联轴器不平衡是诱发泵振动表现出间歇性和自激振特征的主要原因,更换经动平衡的备用联轴器后,设备运行恢复正常.     

Experimental Research on Parallel Conversion Control of Drying Temperature in a Closed-Loop Heat Pump Dryer

The paper proposes a method to handle the challenge of temperature control in a closed-loop heat pump dryer that can operate both in heating cycle and refrigeration cycle. It is hard to avoid the violent fluctuations of drying temperature as the operation mode changes. Hence, the parallel conversion control is introduced to realize the accurate control of drying temperature. The main idea of the controller design lies in the use of different membership functions and fuzzy control rules for the two operation modes. Experimental results show that the temperature fluctuations are reduced when using parallel conversion control with fast and stable response as compared to the fixed-frequency and PID control system. One of the parameters, R _f , representing the value of undershoot ratio is 0.4, 0.48, and 0.64 when drying temperature is fixed at 30, 35, and 38°C, respectively, with a parallel conversion controller. In order to study the application prospects of the parallel conversion control system, a comparison experiment with different compressor frequency ranges was also conducted.