【作者】 武鹏；

【导师】 王乐勤； 吴大转；

【作者基本信息】 浙江大学 ， 化工过程机械， 2013， 博士

【摘要】 机泵产品每年耗电量占全国总发电量的20%左右,其运行效率的提高对节能减排目标的实现有着重要的意义。工业生产中泵的设计和选型,由于系统在设计时无法预估的损失,以及实际生产中可能出现的特殊状况、产能扩大和工艺需求波动等原因,往往需要考虑设计余量,这使得多数离心泵的最佳工况与管路系统的不匹配现象难以避免。泵在非设计工况下运行不但效率显著下降,零部件的可靠性和使用寿命也显著降低。因此,从长周期运行和高效运行的理念出发,研究泵调节与运行控制的机理和技术,对降低泵组系统能耗、提高泵的运行可靠性有极大地意义。本文提出了基于多泵并联运行的智能泵阀系统,通过多泵转速和阀门的联合调节,以及工况分配优化计算,使得泵组的流量和压力在很宽的范围内都能满足系统的实时需求,并保证离心泵始终处于最优工况区域运行,从而大幅提高了泵的效率、可靠性以及适用范围。论文的主要内容包括以下几个方面：(1)介绍了离心泵并联运行和变速调节的工作特性,建立了并联泵组工作点的确定方法；通过分析内部流动状态、漩涡分布及演化规律,总结出离心泵在不同工况下的运行特点及其与泵可靠度的关系；将已有的可靠性数据与泵内部流动特点进行对照分析,建立了泵流量与可靠度的函数。(2)通过对泵外特性曲线的分析,建立了以低功耗和长寿命运行为目标的并联泵组优化计算数学模型和目标函数；研究了基于罚函数法的约束条件处理方法；设计和改进了基本遗传算法用于求解该优化问题。(3)采用拉格朗日乘子法计算了双泵并联系统的最优工况分配方法；同时采用遗传算法计算了双泵并联运行实例,并与实验结果进行了比较分析,理论计算结果、遗传算法计算结果与实验取得了很好的一致；给出了相同多泵同转速并联运行节能的理论依据,并且将遗传算法用于不同型号双泵并联运行优化,并比较分析了支路阀门在并联泵系统中的作用。(4)提出了基于泵阀联合控制和多泵最佳工况自动调节的智能泵组系统结构,比较了传统的单泵变频泵组与本文中智能泵组系统的能耗和运行可靠度,结果表明多泵智能变频系统显著提高了泵组效率及寿命；在此基础上,将前文的优化算法进行了扩展,分别计算了多台同型号或不同型号泵组运行的最优工况分析；将泵可靠度函数整合到优化算法中,建立了基于泵组运行效率与可靠度的优化目标函数。考虑泵组运行的实际需求,对目标函数做了一些简化,使计算程序可以更快的响应需求变化。(5)为了分析双泵并联系统在工况调节过程中的关键参数的动态变化及其对管路系统产生的冲击,基于flowmaster中建立了与实验台相同性能参数的仿真模型。分析了调节过程中各关键节点压力、流量等参数的变化情况,总结出提高泵阀调节过程中可靠性的途径,为实际工况调节提供指导。本文提出了一种基于泵阀联合调节和多泵优化运行的智能泵组结构,构建了实验装置；建立了以提高泵组运行效率和可靠度为目标的运行优化模型,并通过实验验证了智能泵组运行性能和节能效果。研究结果表明本论文提出的智能泵组和优化算法,可以大幅度拓展离心泵机组流量和压力的可调节范围,保证其在各种运行条件下的高效性和可靠性,从而很好地解决工业应用中离心泵系统调节范围小和偏工况低效运行的实际问题。更多还原

【Abstract】 Power consumption of pumps accounts for about20%of the total consumption in China. Therefore, the improvement of the operation efficiency plays an important roal in energy saving and emission reduction. A certain design margin should be considered due to the loss in the process can not be estimated in system design as well as capacity expansion and process requirement fluctuations. So the best condition of the centrifugal pump and piping system are difficult to match. At off-design conditions, not only the pump efficiency is significantly reduced but also the reliability and the service life of components are declined. Therefore, based on the conception of long-term and efficient operation, it is important to reduce the energy consumption of the system and improve the reliability of the pump by studying the mechanism and technology of pump condition adjustment and control.In this paper, a smart pump unit is carried out with parallel pumps.. Based on pump speed and valve adjustment and optimization method, the flowrate and pressure can meet the real-time requirements of the system in a very wide range and ensure that the operating conditions are near the best efficiency point. So the efficiency, reliability and the operating range of the pump system are increased significiently. The main content includes the following aspects:(1) The operating characteristics of parallel centrifugal pump and speed adjustment were introduced; the method to calculate the operation point of parallel pump system was built up; the internal flow, swirl distribution and evolution were simulated; the characteristics of centrifugal pump running in different operating conditions and the relationship with pump reliability were summarized; pump reliability function curve was carried out by comparing and analyzing the reliability data and the internal flow characteristics of pump.(2) Based on the analysis of pump external characteristics, the mathematical model and objective function for low power consumption and long service life were built up; constraint processing method based on the penalty function was studied and a genetic algorithm was design and improved for solving the optimization problem.(3) The optimal operating condition for double pump parallel system was calculated using the method of the Lagrange multiplier; a pump system with two identical pumps in parallel was calculated using genetic algorithms and compared with the experimental results and the theoretical results. Results show that genetic algorithm, theoretical and experimental achieved good agreement; the genetic algorithm is used for different models of dual-pump parallel operation optimization and comparative analysis of the branch valve in parallel pump system.(4) The structure of the smart pump unit was proposed, which is based on valve-speed joint control and operating condition automatically adjustment. The energy consumption and operating reliability of the traditional pump unit with single variable frequency pump and smart pump unit in this article were compared, and result shows that the smart pump system improved the efficiency and reliability significantly; Based on the study above, the optimization algorithm was extended to more than one pump, and a muti-pump system was calculated; the reliability function of the pump was integrated into the optimization algorithm, and the objective function was simplified so that the calculation program can respond faster to changes in demand.(5) In order to analyze the impact of the piping system during dual-pump parallel system adjustment process, a model with the same performance parameters of the test bench was built up in Flowmaster. The pressure, flowrate and other parameters of the key node were analyzed; the way to improve the reliability during adjustment process was sumrized. The results provide guidances for the actual working conditions.In this paper, a smart pump system was proposed based on valve-speed joint adjustment and operating condition optimizing, and the test bench was constructed; The optimizing calculation was carried out to to increase the efficiency and reliability of the pump unit and the results was verified by experiments. The results show that the smart pump unit studied in this paper can increase the flowrate and pressure range significantly under high efficiency and reliability. So the problem in which the operating condition is deviated from the design condition is solved in a certain extent.更多还原