基于非接触电阻抗测量的气液两相流参数检测新方法研究

发布时间：2018-05-06 03:11

  本文选题：气液两相流 + 参数测量　； 参考：《浙江大学》2017年博士论文

【摘要】：气液两相流在工业过程中涉及范围十分广泛,其参数的有效测量是一个具有重大意义但仍未得到较好解决的课题。基于等效电导检测的气液两相流参数检测方法具有结构简单和实时响应快等优点而得到广泛关注,但该方法仍然存在两方面不足:在测量机理方面,现有的电导检测方法主要是接触式的,其检测电极直接与被测流体接触,会引起电极极化和电化学腐蚀等问题;在测量信息方面,现有的电导检测方法以获取流体等效电导信号为目的,但对复杂的气液两相流体而言,包含更多流动特征的完整电阻抗信息(实部、虚部和幅值)的获取将更有利于气液两相流参数检测。本学位论文针对以上两个问题,对现有的电容耦合式非接触电导检测(Capacitively Coupled Contactless Conductivity Detection,C4D)技术存在的问题进行改进,研发了新型非接触式电阻抗传感器,利用完整电阻抗信息实现气液两相流参数测量。本学位论文中的主要创新点和贡献如下:1、为克服本课题组已有工业型C4D传感器存在的输入输出特性呈现非单调性的不足,提出了一种基于双电感串联谐振的非接触式电导检测新方法,研发了一种工业型双电感结构C4D传感器。该方法在激励电极和检测电极端各串联一个电感器件,不仅克服了耦合电容对测量的不利影响,还解决了已有工业型C4D传感器输入输出特性的非单调性的问题。实验结果表明,所提出的基于双电感串联谐振的非接触式电导检测新方法是有效的,所研发的工业型双电感结构C4D传感器是成功的。在四种管道(内径分别为1.8 mm、3.3 mm、5.0 mm和7.6mm)中,电导测量最大相对误差均小于4%。2、针对实际电感存在电感可调范围窄、大电感制造困难和体积较大等问题,引入模拟电感技术,提出了基于模拟电感串联谐振的非接触式电导检测新方法。研发了对称浮置模拟电感以及基于对称浮置模拟电感的C4D传感器。研究结果表明,对称浮置模拟电感和该新型C4D传感器的设计是成功的,称浮置模拟电感等效电感值调节大并可实现较大电感值,采用对称浮置模拟电感的C4D传感器的性能和电导测量精度令人满意。在三种管道(内径分别为3.0 mm、4.6 mm和6.4 mm)中,电导测量最大相对误差均小于5%。3、针对对称浮置模拟电感存在的结构复杂、运行稳定性需重点考虑等问题,研发了两种基于接地模拟电感的C4D传感器:A(利用电流转电压的原理)和B(测量分压电阻两端电压差的原理)。在三种管道(内径分别为3.0mm、4.6mm和6.4 mm)中利用C4D传感器A和C4D传感器B进行电导测量实验。实验结果表明,接地模拟电感和新型C4D传感器的设计是成功的。与对称浮置模拟电感相比,接地模拟电感具有结构简单和运行稳定性较好等优点。基于接地模拟电感的C4D传感器的电导测量精度也令人满意(三种管径下,新型C4D传感器A和B的电导测量最大相对误差分别为4.5%和5.0%),且C4D传感器A的整体测量性能较C4D传感器B更好。4、结合接地模拟电感阻抗相消技术和数字相敏解调(DPSD)技术提出了一种非接触式电阻抗测量新方法,研发了一种新型非接触式电阻抗传感器。该非接触式电阻抗测量方法根据阻抗相消原理克服耦合电容对电阻抗测量的不利影响,利用DPSD技术获取气液两相流的完整电阻抗(实部、虚部和幅值)信息。模拟和实际流体测量实验表明:所提出的非接触式电阻抗测量方法是有效的,所研发的新型非接触式电阻抗传感器是成功的。模拟测量实验中,电阻测量和电容测量的最大相对误差分别为3.7%和2.4%,电阻-电容组合测量实验中,电阻和电容测量的最大相对误差分别为2.1%和5.1%;实际流体测量实验中,KC1溶液电导率测量和有机溶剂介电常数测量的最大相对误差分别为3.7%和5.8%。5、将所研发的新型非接触式电阻抗传感器与小波分析和k均值聚类方法相结合提出了一种基于非接触电阻抗测量的气液两相流流型辨识新方法。该方法采用小波分析提取所获电阻抗信号各部分的频域特征,结合电阻抗信号的统计特征构成特征向量,利用以马氏距离作为距离度量指标的k均值聚类方法进行流型分类。三种管径(3.0mm、4.0mm和7.0mm)下的流型辨识实验结果表明,所提出的流型辨识新方法是有效的。利用实部、虚部、幅值和完整电阻抗信号对泡状流和段塞流进行辨识的最低准确率分别为91.1%和90.9%、90.2%和87.9%、92.7%和87.0%及91.1%和93.5%。采用完整电阻抗信号的整体流型辨识效果略优于单独采用实部、虚部或幅值信号的流型辨识效果。6、提出了一种基于非接触电阻抗测量的气液两相流相含率测量新方法。该方法充分利用电阻抗各部分信息,结合最小二乘法,建立不同流型相含率测量模型,实际测量时根据流型判别结果选择相应的相含率测量模型并最终实现相含率测量。三种不同管径(3.0mm、4.0mm和7.0mm)泡状流和段塞流下的实验研究结果表明所提出的相含率测量新方法是可行的和有效的,充分利用气液两相流完整电阻抗信息(实部,虚部和幅值)有助于相含率测量精度的提高。
[Abstract]:Gas-liquid two-phase flow is widely involved in the industrial process. The effective measurement of its parameters is a subject which is of great significance but is still not well solved. The method of gas liquid two-phase flow parameter detection based on equivalent conductance detection has been paid wide attention to the advantages of simple structure and fast real-time response, but the method still exists. The two aspects are insufficient: in the measurement mechanism, the current conductance detection method is mainly contact type. The detection electrode directly contacts with the measured fluid, causes electrode polarization and electrochemical corrosion. In the measurement information, the current conductance detection method is aimed at obtaining the fluid equivalent conductance signal, but the complex gas-liquid two phases are used. For fluid, the acquisition of integrated electrical impedance information (real part, virtual part and amplitude) containing more flow characteristics will be more conducive to the detection of gas-liquid two-phase flow parameters. In this dissertation, the existing Capacitively Coupled Contactless Conductivity Detection (C4D) technology exists for the existing capacitive coupling non-contact conductivity detection (Capacitively Detection, C4D). The main innovation points and contributions in this dissertation are as follows: 1, in order to overcome the inadequacy of the input and output characteristics of the existing industrial C4D sensors in our research group, a new method is proposed. Based on a new method of non contact conductance detection based on double inductor series resonance, an industrial dual inductor C4D sensor is developed. This method is connected with an inductor at the exciting electrode and the detection electrode. It not only overcomes the negative influence of the coupling capacitance on the measurement, but also solves the input and output characteristics of the existing industrial type C4D sensors. The experimental results show that the new method of non-contact conductivity detection based on double inductance series resonance is effective. The developed industrial dual inductor structure C4D sensor is successful. The maximum relative error of the conductance measurement is less than 4%. in four kinds of pipes (1.8 mm, 3.3 mm, 5 mm and 7.6mm respectively). 2, in view of the narrow inductance of the inductor, the difficulty in producing large inductors and the larger size of the inductor, a new method of non contact conductance detection based on the analog inductor series resonance is proposed. The symmetrical floating analog inductor and the C4D sensor based on the symmetrical floating inductance are developed. The design of the symmetrical floating analog inductor and the new C4D sensor is successful. It is said that the equivalent inductance value of the floating analog inductor can be adjusted greatly and the inductance value can be realized. The performance and the conductivity measurement precision of the C4D sensor with symmetrical floating analog inductance are satisfactory. In the three kinds of pipes (3 mm, 4.6 mm and 6.4 mm respectively), the conductance measurement The maximum relative error is less than 5%.3. In view of the complex structure of the symmetrical floating analog inductor and the operation stability, two kinds of C4D sensors based on grounding analog inductors are developed: A (using the principle of current transfer voltage) and B (the principle of measuring voltage difference at the two end of the voltage divider). In the three kinds of pipes, the internal diameter is 3.0m, respectively. M, 4.6mm and 6.4 mm) use C4D sensor A and C4D sensor B to carry out conductance measurement experiments. Experimental results show that the design of ground Analog inductors and new C4D sensors is successful. Compared with symmetric floating analog inductors, the ground Analog inductors have the advantages of simple structure and good operation stability. The conductivity measurement accuracy of the sensor is also satisfactory (the maximum relative error of the electrical conductivity measurement of the new C4D sensor A and B is 4.5% and 5% respectively), and the overall measurement performance of the C4D sensor A is better than that of the C4D sensor B, and a non contact with the grounding analog inductance impedance cancellation technique and the digital phase sensitive demodulation (DPSD) technology is proposed. A new non contact electrical impedance sensor is developed. The non-contact impedance measurement method overcomes the adverse effect of the coupling capacitance on the impedance measurement based on the impedance cancellation principle. The DPSD technology is used to obtain the complete impedance (real part, imaginary part and amplitude) information of the gas-liquid two phase flow. The measurement experiments show that the proposed non-contact impedance measurement method is effective and the new type of non-contact electrical impedance sensor developed is successful. The maximum relative error of resistance measurement and capacitance measurement is 3.7% and 2.4% respectively in the simulated measurement experiment. The maximum phase of resistance and capacitance measurement in the resistance capacitance measurement experiment The errors are 2.1% and 5.1% respectively. In the actual fluid measurement experiments, the maximum relative errors of the measurement of KC1 solution conductivity and the dielectric constant of organic solvents are 3.7% and 5.8%.5 respectively. A new type of non-contact electrical impedance sensor, combined with wavelet analysis and K mean clustering, is put forward based on the non contact resistance measurement. A new method for identifying the flow pattern of gas-liquid two phase flow is used. This method uses the wavelet analysis to extract the frequency domain characteristics of all parts of the impedance signal, and combines the statistical characteristics of the electrical impedance signal to form the characteristic vector. The flow pattern classification is carried out by using the K means clustering method which takes martensitic distance as a distance measure. Three kinds of pipe diameter (3.0mm, 4.0mm and 7.0mm) are used. The flow pattern identification results show that the proposed flow pattern identification method is effective. The minimum accuracy of identification of bubbly flow and slug flow using real parts, imaginary parts, amplitude and integrated impedance signals is 91.1% and 90.9%, 90.2% and 87.9%, 92.7% and 87%, 91.1% and 93.5%. are identified as the integral flow pattern identification of integrated electrical impedance signals. The effect is slightly better than the flow pattern identification effect of the real part, the imaginary part or the amplitude signal.6. A new method for measuring the phase holdup of gas-liquid two-phase flow based on the non contact impedance measurement is proposed. This method makes full use of the information of the electrical impedance and the least square method to establish the measurement model of the phase holdup of different flow patterns, and the actual measurement is based on the flow. The phase holdup measurement model is selected and the phase holdup measurement is finally realized. The experimental results of three different pipe diameter (3.0mm, 4.0mm and 7.0mm) bubbly flow and slug flow show that the proposed phase holdup method is feasible and effective, and fully utilizes the integrated electrical impedance information (real part, virtual part and the virtual part) of the gas liquid two phase flow. The amplitude is helpful to the improvement of the measurement accuracy of the phase holdup.

【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O359.1
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本文编号：1850516