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.

Design and Operation of Municipal Rain and Sewage United Pumping Station

In the process of designing a municipal rainwater and sewage pumping station,it is necessary to accurately grasp the design points,reasonably determine the scale of the rainwater and sewage pumping station,scientifically select the location and layout,and select materials reasonably.After completing the process design of the municipal rainwater and sewage pumping station and putting it into operation,in order to ensure the normal and stable operation of the pumping station,it is necessary to focus on strengthening the operation and management of diving equipment,cleaning equipment,and electromechanical equipment.The author analyzes the key points and specific design path of the process design of municipal rainwater and sewage pumping stations,and puts forward effective strategies for operation management,hoping to contribute to the scientific design and stable operation of municipal rainwater and sewage pumping stations.

Feasibility analysis of urban sewage source heat pump system with freezing latent heat collection

Aiming to resolve the problem that conventional sewage source heat pump systems cannot satisfy heat peak loads of buildings,a new idea that the freezing latent heat is exacted as the auxiliary heat source at the peak heat load is proposed.First,on the basis of sewage characteristics,a freezing latent heat exchanger is developed to safely eliminate ice,continuously extract heat and remove sewage soft-dirt.A reasonable form of the urban sewage source heat pump system with freezing latent heat collection is presented.Then,the feasibility of the system is theoretically analyzed.The calculation results under typical operating conditions show that the heating ability of the new system is higher than that of the conventional one and the ratio of these two highest heating rates is between 4.5 and 8.7,which proves that the new system has great application potential in cold regions.

NUMERICAL SIMULATION FOR INCOMPRESSIBLE TURBULENT FLOW IN THE IMPELLER OF SEWAGE PUMP

The 3-D turbulent flow in the impeller of sewage pump is simulated. Thetime-averaged N-S equations and the kappa-epsilon turbulent model is modified. The calculation iscarried out in body-fitted coordinated grid by applying SIMPLE-C algorithm. The calculated velocity,pressure distributions of the turbulent flow in the sewage pump are obtained for the first time,which will be helpful for the optimal design and performance prediction of sewage pumps on the basisof flow field simulation.

Numerical investigation on self-priming process of self-priming pump

In order to investigate the self-priming process of the self-priming pump,an unsteady simulation was conducted where the Navier-Stokes equations were used with the Lagrangian-Eularian mo-del.In course of this investigation,the volume fractions,pressure distribution and self-priming time were carried out.By analyzing the volume,velocity and pressure distribution of the gas-liquid two-phase flow at different time,the two-phase content via the variation law of the two-phase flow in the pump was carried out.By monitoring and analyzing the gas-liquid flow at the outlet of the pump,the self-priming time and crucial periods were given.Two phenomena were mainly characterized by the self-priming process such as the gas-liquid mixing and separation,which occur in the early stage of self-priming process.During that period the gas-liquid mixing clouds appear on the outer edge of the impeller,and the instantaneous void fraction at the inlet and outlet of the impeller decreases obviously.It was also established from the transient study that the gas has a major influence on the hydraulic performance of the pump at the early stage of operation.To increase the usage of self-priming pump and to also understand the energy conversion of the pump,it is very essential to investigate and establish the basic working principle of the self-priming pump.

Parallel Operation Characteristics Analysis of Sewage Source Heat Pump Units in Winter

Sewage source heat pump unit operates under partial load most of the time, and study on the law of coefficient of performance (COP) of the unit varying with load ratio can provide basis for the heat pump units running in high efficiency. A mathematical model determining COP, evaporation temperature and condensation temperature of a single unit was proposed. Under the condition of uniform load distribution, the model was established according to different ways of bearing partial load with the same type multi...

Applicability of sewage heat pump air-conditioning system

A sewage heat pump system and its application based on a project in Chongqing,China,were discussed. Based on the sewage conditions,a feasibility analysis of the sewage heat pump air conditioning system was conducted. The theoretical and quantitative calculations indicate that sewage flux in the city sewage main pipe in the project can satisfy heat exchange requirements,and taking water from the pipes has relatively small influence on the pipe net in summer and winter. The sewage heat pump air-conditioning system can save 21.5% operating cost in one year,which is energy efficient and environmentally friendly.

Strong self-flushing technique for heat exchanger of sewage source heat pump system

To better remove the contamination on the surface of a heat-exchanger in urban sewage source heat pump system （USSHPS）, this paper analyzes the feasibility of strong self-flushing on the basis of experiments and presents a new on-line self-flushing technique, which alternately flushes part of heat transfer tubes. In addition, operation principles and the structure of the new heat-exchanger are introduced and the feasible economi- cal and technological cleaning plans are given by design calculation and scheme comparison. The result shows that keeping each tube washed for one minute with 5 m/s, the operating cost is lower than ￥5 and when one flushing pump ahemately flushes 10-20 heat exchangers, the saved costs of flushing 10 tubes alternately are over 4 times of the increased costs.

Effects of Particle Concentration on the Dynamics of a Single-Channel Sewage Pump under Low-Flow-Rate Conditions

Single-channel sewage pumps are generally used to transport solid-liquid two-phase media consisting of a fluid and solid particles due to the good non-clogging property of such devices.However,the non-axisymmetric structure of the impeller of this type of pumps generally induces flow asymmetry,oscillatory outflow during operations,and hydraulic imbalance.In severe cases,these effects can jeopardize the safety and stability of the overall pump.In the present study,such a problem is investigated in the framework of a Mixture multiphase flow method coupled with a RNG turbulence model used to determine the structure of the flow field and the related motion of transported particles.It is shown that under different inlet particle concentrations,the flow field in the pump exhibits periodic variations of the pressure.The volume fraction of solid particles at the trailing edge of the suction surface of the blade is the largest,and solid particles tend to be concentrated at the outer edge of the pump body.With a rise in import particle content,the pressure and volume fraction of particles in the sewage pump also increase;for a fixed inlet particle concentration,the pressure pulsation amplitude increases with an increase in the flow rate.In addition,under small flow conditions,as the inlet particle concentration increases,the flow field leaving the sewage pump diaphragm near the outlet of the volute becomes more turbulent,and even a secondary back-flow vortex appears.

Design and Analysis of a Small Sewage Source Heat Pump Triple Supply System

Based on the characteristics of sewage from beauty salons,a simulation model of a small sewage source heat pump triple supply system that can be applied to such places is established to optimize the operating conditions of the system.The results show that with the increase of sewage temperature and flow,the performance of the system also increases.In summer conditions,the system provides cooling,recovers waste heat and condensed heat from sewage,with a COP value of 8.97;in winter conditions,the system heats and produces hot water,with a COP value of 2.44;in transitional seasons,only hot water is produced.The COP value is 2.75.Compared with the traditional systems which refers to the air source heat pump and hot water boiler system currently used in beauty salons,this system can save energy by 50.9%.

Influence of the Area of the Reflux Hole on the Performance of a Self-Priming Pumnp

The self-priming process of a pump involves a complex gas-liquid two-phase flow.Studying the distribution of gas and water and the evolution of their flow in the pump is of great importance to optimize this process and shorten the pump self-priming time.In the present study,a standard k-εturbulence model and a multiphase flow model have been used to simulate the self-priming pump process considering four different reflux hole areas.A comparison of the distribution of air and water distribution on the axial surface and inside the volume have been carried out for the different considered cases.The pattern formed by the streamlines at different times during the whole self-priming process has also been investigated.The results show that the velocity at the trailing edge of the impeller outlet is the largest.The flow in the pump cavity is.complicated by the formation of vortices.The number,shape and location of the vortices change depending on the considered configuration.

某油田联合站污水余热利用研究

原油集输系统中的热化学沉降脱水,需要将原油温度升高,这一过程将消耗大量能源,其燃料主要为天然气,加热产生大量的CO_(2)。文中通过对某油田联合站生产流程研究分析,同时结合站内用热情况,确定采用压缩式热泵替代现有燃气加热炉技术路线,用于冬季采暖和一段原油加热。项目实施后,每年可节能源8932×10^(4) MJ,折合标煤减少3481.8 t,减少CO_(2)排放2024.5 t,每年可节省能源消耗费用651.8万元,节能减排效果显著,该研究对油田联合站清洁能源替代,减少CO_(2)排放具有重要意义。

基于某商务区多源耦合供热系统运行研究

为了实现“双碳”目标,提高可再生能源的利用率,减少碳排放量,对沈阳某商务区进行规划,充分发挥区域内地热能、污水能等可再生能源灵活供热的特点,以地源热泵+污水源热泵+电锅炉3种热源耦合进行供热,为区域综合能源多能互补、灵活调度提供参考。利用DeST模拟软件建立区域建筑模型,模拟出区域建筑供暖季逐时热负荷;通过TRNSYS软件建立区域综合能源系统模型,以某典型设计为例,分别讨论了在5种工况下该耦合供热系统峰谷电时段的运行策略,并采用费用年值法对系统经济性进行分析。结果显示:该区域内办公类建筑热负荷最大;系统不蓄热时初投资最小,由于在电高峰时段增加了电锅炉运行时长,导致系统运行费用增加,系统整体经济性变差;在蓄热率为100%时,该耦合供热系统初投资较大,但运行费用较低,系统费用年值最小,经济性最优,体现了蓄热方案下降低运行费用的优势。

驱动源及低温热源双向梯级利用热泵工艺研究

为提高一次能源利用效率,针对大庆油田吸收式热泵余热提取工艺进行了改进,采用驱动源和低温热源双向梯级利用热泵工艺,提高了能源利用效率。传统热泵工艺COP为1.7,采用双效梯级利用工艺COP达到2.7。双向梯级利用热泵工艺为耦合蒸汽直拖离心式热泵和蒸汽驱动吸收式热泵对余热余压梯级利用的工艺流程,利用中温中压蒸汽梯级驱动两级热泵,充分发挥了蒸汽的做功能力;同时梯级提取含油污水低温余热,使含油污水温度从35℃降至21℃,传统热泵工艺从35℃降至25℃。综合能源利用效率较传统热泵工艺提高了50%。

污水泵内颗粒通过性能及流动损失特性研究

为了研究柱状颗粒参数对污水泵内固液两相流动特性以及通过性能的影响规律,采用CFD-DEM耦合方法计算了离心泵内固液两相流动,基于熵产理论分析了不同颗粒物性条件下泵内的流动损失特性,并通过试验对其进行了验证。结果表明:柱状颗粒长径比、体积分数和密度影响了污水泵内颗粒的通过性能以及流动损失;固相浓度从1%增大至5%,泵的扬程降低1.97 m,效率降低2.2%,颗粒通过能力逐渐降低;颗粒密度从1000 kg/m^(3)增大至2500 kg/m^(3),泵的扬程降低1.63 m,效率降低3.76%,颗粒通过能力略有增强;在各工况下,总熵产变化规律与泵性能变化规律一致,高熵产区域主要集中在叶片进口边附近,说明熵产分析能够有效反映泵内的流动损失特性。研究结果可为污水泵的优化设计提供理论依据。

矿山井下排污水系统自动化应用研究

矿山井下水仓排水系统多采用自吸式排污泵进行排放污水,排水期间需要人员手动开启水泵及阀门,并且需对水泵的排水状况进行实时监管,否则当水仓内污水排空时,若不及时关闭水泵及阀门则会引发电机烧毁、泵头机械密封损坏等一系列故障。针对这一现状,本文对矿山井下水仓排污水系统进行自动化控制改造,在原有排水系统的基础上增设电动偏心半球阀、水位传感器、搅拌机以及电气控制系统等相关部件,利用水位传感器的信号电动控制水泵的启停以阀门的开关,同时优化安装工艺并进行调试,实现了排水自动化。经过对比分析,系统故障率下降了60%,现场使用效果显著,减轻了维修人员的工作量,切实提高了矿井排水的安全性以及稳定性。

双螺旋转子泵在油田污水处理系统中的应用

油田污水处理站是地面工艺系统的重要站场,污水回收泵是其中主要耗能设备之一。当前在用的污水回收泵为卧式螺杆泵,采取负压回收方式,受采出液特性影响,螺杆泵运行状况不稳定,其表现为故障频繁、能耗高、维修费用高,困扰油田生产。为此,某油田应用双螺旋转子泵替代螺杆泵工艺,更换后,平均单台能耗下降30%,共节省电量约32×10^(4) kWh,节约维修成本费用80万元。通过对螺杆泵工艺现状进行客观论述,对双螺旋转子泵应用情况进行客观分析评价,为油田污水回收工艺提供借鉴参考。

排污泵站内流特性数值模拟与模型试验优化研究

基于RNG k-ε紊流模型,采用三维数值模拟技术,分析了排污泵站的内流特性,基于佛汝德相似准则搭建了模型比例为1∶1的排污泵站模型试验台,测试了正向高位进水工况下的泵站内部流动状态,验证了数值模拟的准确性、可靠性。通过对比分析排污泵站内部不同结构形式下的水泵的流动模式、漩涡及喇叭管吸入口预旋,评估泵站底部防旋板、隔板对排污泵运行的安全稳定可靠性的影响,为排污泵站内部不良流态的优化提供参考依据。研究表明,在泵站底部增加防旋板和隔板这种结构形式对改善泵站内部流态和喇叭管吸入口进水条件、降低漩涡风险及预旋风险具有很大的作用,可以保证排污泵的安全稳定运行。数值模拟与模型试验的结果为排污泵站的改进优化提供了方向,该研究为相似排污泵站设计和改造过程中的方案优化提供了一定的参考依据。

地坑排污泵空转原因分析与解决方案

地坑排污泵是地坑污水处理系统的重要输送设备,一旦故障,将影响整个排污系统的正常运行。以某厂连退机组涂层段地坑排污泵为例,在上机运行不足1个月,再次报警,无法完成工作需要,经下机后解体检查,发现泵内部轴承润滑不良、叶轮和泵盖严重磨损等。针对排污泵在检维修中发现的各种问题,分析产生各类故障的原因,最终诊断为泵长时间空转,并提出地坑排污泵的改进方法,延长使用寿命。

污水泵站恶臭气体排放预测模型研究

城市污水泵站在运行过程中会散发难闻的恶臭气体,已成为扰民的主要环境问题,对周边居民的生活质量造成影响。研究选择有代表性的污水泵站,在厂界和泵站的敏感点位安装在线式恶臭气体监测仪,通过连续在线式监测恶臭气体的排放情况,获得大量的周期性的监测数据。对获得的大量监测数据进行整理和分析,建立数学算法预测模型,再把模型加载到数据监测平台中,通过对污水泵站的实时监测,验证模型预测的适用性和准确性,在此过程不断的调整模型相关参数,用来提高模型预测的适用性和准确性,研究旨在为污水泵站恶臭气体的控制提供重要的理论依据。