双极性脉冲磁场装置研制及阻垢实验研究

发布时间：2018-08-04 17:07

【摘要】：污垢是电力、化工等工业领域中的常见问题,如何阻垢除垢也是技术难题。多年来,磁场阻垢除垢作为一种水处理技术因其简便、经济无污染等优点得到了广泛的研究。本文设计了一套双极性脉冲磁场发生装置,并对磁场发生装置的气隙磁场进行了仿真分析。首先计算得到基于钕铁硼N40的永磁体磁场发生装置在水处理腔体产生的磁感应强度均匀度Δ小于0.15%,满足磁场阻垢实验中磁感应强度均匀性的要求。然后,依据Maxwell方程组的基本理论,分析发现,由多个扇形永磁体组装成的圆环型磁场装置的磁感应强度不能通过基本的电磁场理论计算法列写方程组进行计算,必须通过数值计算的有限元法进行求解分析。接着,运用ANSYS仿真得到了磁场发生装置的水处理腔内磁感应强度分布规律,即在有效间距0.02m内磁感应强度一直保持在0.4T,并且当圆环型装置旋转一周时,处理腔内中心点处的磁感应强度可以从-0.4T到0.4T交替变化4次,从而在水管内形成了磁感应强度大小为0.4T的双极性脉冲磁场,并且垂直于水流方向。本文利用双极性脉冲磁场发生装置、循环水装置和测量仪器研制了一套微型循环水多参数监测的磁场阻垢实验平台。实验平台采用LabX软件对pH值、电导率和温度值进行在线监测,缩短了数据记录的时间间隔,降低了人工记录的工作量。通过预实验验证了阻垢实验的可重复性。正交阻垢实验的数据表明,阻垢效果最好的是初始钙离子浓度为6mmol/L、脉冲磁场频率为40Hz、循环水温度为40°C时,此时阻垢率为49.33%。对正交阻垢实验结果进行方差分析,得到三因素三水平下对阻垢率的影响程度依次为脉冲磁场频率、初始钙离子浓度和水温度,其中,最优阻垢参数为初始钙离子浓度5mmol/L、脉冲磁场频率40Hz、循环水温度40°C。实验中发现pH值存在波动现象,且温度越高波动越剧烈。最后,进行了钙离子浓度、电导率与时间的相关性研究,建立了基于脉冲磁场正交阻垢实验的BP神经网络模型,并结合此模型与遗传算法进行了阻垢参数寻优。结果表明,脉冲磁场对循环水溶液中离子的稳定状态有促进作用,随着频率的升高,钙离子达到平衡的时间越短。然后以BP神经网络建立的预测模型为遗传算法的适应度函数,进行磁场阻垢实验参数寻优,得到了一定范围内阻垢率的最大值84.37%,对应的最佳阻垢实验参数为磁场频率77.5Hz;磁感应强度0.395T;钙离子初始浓度4.45mmol/L;温度56.86°C。
[Abstract]:Fouling is a common problem in industry such as electric power and chemical industry. For many years, magnetic field scale inhibition and scale removal as a water treatment technology has been widely studied because of its advantages of simplicity, economy and no pollution. In this paper, a set of bipolar pulsed magnetic field generator is designed, and the air gap magnetic field of the magnetic field generator is simulated and analyzed. First, the magnetic induction intensity uniformity 螖 of the permanent magnet based on NdFeB N40 in the water treatment chamber is less than 0.15, which meets the requirement of uniformity of magnetic induction intensity in the magnetic field scale inhibition experiment. Then, according to the basic theory of the Maxwell equations, it is found that the magnetic induction intensity of the ring magnetic field device assembled by multiple sector permanent magnets can not be calculated by the basic electromagnetic theory calculation method. The finite element method must be used to solve the problem. Then, the distribution law of magnetic induction intensity in the water treatment cavity of the magnetic field generator is obtained by ANSYS simulation, that is, the magnetic induction intensity is kept at 0.4T within the effective spacing of 0.02m, and when the annular device rotates one week, The intensity of magnetic induction at the center of the cavity can be changed four times from -0.4T to 0.4T, thus a bipolar pulsed magnetic field with 0.4 T magnetic induction intensity is formed in the water pipe, which is perpendicular to the direction of water flow. In this paper, a magnetic field scale inhibition experimental platform for multi-parameter monitoring of miniature circulating water has been developed by using bipolar pulse magnetic field generator, circulating water device and measuring instrument. The LabX software is used to monitor the pH, conductivity and temperature online, which shortens the time interval of data recording and reduces the workload of manual recording. The repeatability of scale inhibition experiment was verified by pre-experiment. The results of orthogonal scale inhibition experiment show that the best scale inhibition effect is when the initial concentration of calcium ion is 6 mmol / L, the frequency of pulse magnetic field is 40 Hz, and the temperature of circulating water is 40 掳C, and the scale inhibition rate is 49.33. The variance analysis of the results of orthogonal scale inhibition experiment shows that the influence of three factors and three levels on the scale inhibition rate is in turn the frequency of pulse magnetic field, the initial calcium ion concentration and the water temperature. The optimal scale inhibition parameters are: initial calcium concentration of 5 mmol / L, pulse magnetic field frequency of 40 Hz, circulating water temperature of 40 掳C. It was found that the pH value fluctuated, and the higher the temperature was, the more violent the fluctuation was. Finally, the correlation between calcium ion concentration, conductivity and time is studied, and BP neural network model based on orthogonal scale inhibition experiment of pulsed magnetic field is established, and the scale inhibition parameters are optimized by combining this model with genetic algorithm. The results show that the pulsed magnetic field can promote the stable state of ions in circulating aqueous solution. With the increase of frequency, the time of calcium ion reaching equilibrium is shorter. Then the prediction model established by BP neural network is used as the fitness function of genetic algorithm to optimize the experimental parameters of magnetic field scale inhibition. The maximum scale inhibition rate of a certain range is 84.37. The optimum scale inhibition parameters are magnetic field frequency 77.5 Hz, magnetic induction intensity 0.395T, initial concentration of calcium ion 4.45 mmol / L, temperature 56.86 掳C.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ085.4

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