电容成象传感器结构仿真与检测系统的研究
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摘要
两相流参数测量在工业生产和科学研究中有重要意义。两相流测量技术中迅速发展起来的过程层析成象(PT)，在两相流流动参数分布状况的测量方面取得了一定进展。通过过程成象可以实时地反映过程容器的物料状态，观察设备运行情况，对工业过程进行在线检测。
电容成象技术(ECT)是过程成象技术中首先发展起来的，它具有系统成本低，成象速度快，适用范围广，非侵入式等优点。本文对电容成象系统的传感器结构进行仿真研究，同时对电容层析成象的数据采集系统系统进行研究。
1．通过对电容传感器的结构分析建立传感器的数学模型。分别对传感器的极板张角θ、管壁厚度R_2-R_1、屏蔽层内填充材料的介电常数ε_s、管壁相对介电常数ε_(pw)、屏蔽层厚度R_3-R_2等结构参数以及对传感器极板组合与非组合工作方式、浮置与非浮置方式对传感器性能的影响进行有限元仿真，得出各结构参数和工作方式对传感器性能影响的规律，并根据特定管道确定电容传感器的各结构参数值。
2．本数据采集系统采用了具有抗杂散电容特性的直流充／放电检测电路，并阐述了电容充／放电形式的检测电路及数据采集系统。系统采用直流补偿的方法来消除静态电容和电荷注入电容。采用多通道并行的检测方式来提高检测的速度。由于被测电容的动态范围较大，本论文采用了自寻增益数控放大器，使得信号能够被充分放大，从而提高系统的检测微弱信号的能力，同时还提高了数据采集速度。并对部分电路进行电路验证。
文章的最后提出了进一步研究的建议。
Measuring the parameters of two-phase flow is important in the industrial production and scientific research. As a rapidly developed measuring method, Process Tomography (PT) technique has some achievements in measuring the parameters distributing of two-phase flow. PT technique provides novel means of visualizing the internal behavior of industrial processes. The tomographic images produced by PT system provide valuable information for the assessment of equipment designs and the on-line monitoring of industrial processes.
Electrical Capacitance Tomography (ECT) is one of the techniques, which is firstly developed for PT. It has low-cost, high-speed, robust and non-intrusive. In this paper the ECT sensor structures and the data acquisitions system for ECT have been studied.
1 The sensor model was built by analyzing ECT sensor structure. To obtain the disciplinarian of configuration parameters and operation way to influence of ECT sensor performance by finite emulating. Configuration parameters and operation way included the electrode angle 0, the thickness of pipe wall (R2-R1), the relative permittivity value of pipe wall (epw), the thickness of screen layer (R3-R2), the relative permittivity value of screen layer (es), combined electrode and uncombined electrode and floating electrode and non-floating electrode. The configuration parameters of given pipe based on the disciplinarian.
2 The data acquisition system adopted the charge / discharge capacitance measuring circuit. This paper described the charge/discharge circuit and data acquisition. The data acquisition system used the DC offset compensation method to balance both the standing capacitance and the charge injection capacitance. To increase the overall data acquisition speed, parallel measurement channels were used. Because of wide dynamic range of measurement, a self-optimizing digital-control gain amplifier was presented to
satisfy the different sensitivity requirements. The gain amplifier also can increase the data acquisition speed at the same time. Lastly, the paper gave some suggestion for future study.
电容成象技术(ECT)是过程成象技术中首先发展起来的，它具有系统成本低，成象速度快，适用范围广，非侵入式等优点。本文对电容成象系统的传感器结构进行仿真研究，同时对电容层析成象的数据采集系统系统进行研究。
1．通过对电容传感器的结构分析建立传感器的数学模型。分别对传感器的极板张角θ、管壁厚度R_2-R_1、屏蔽层内填充材料的介电常数ε_s、管壁相对介电常数ε_(pw)、屏蔽层厚度R_3-R_2等结构参数以及对传感器极板组合与非组合工作方式、浮置与非浮置方式对传感器性能的影响进行有限元仿真，得出各结构参数和工作方式对传感器性能影响的规律，并根据特定管道确定电容传感器的各结构参数值。
2．本数据采集系统采用了具有抗杂散电容特性的直流充／放电检测电路，并阐述了电容充／放电形式的检测电路及数据采集系统。系统采用直流补偿的方法来消除静态电容和电荷注入电容。采用多通道并行的检测方式来提高检测的速度。由于被测电容的动态范围较大，本论文采用了自寻增益数控放大器，使得信号能够被充分放大，从而提高系统的检测微弱信号的能力，同时还提高了数据采集速度。并对部分电路进行电路验证。
文章的最后提出了进一步研究的建议。
Measuring the parameters of two-phase flow is important in the industrial production and scientific research. As a rapidly developed measuring method, Process Tomography (PT) technique has some achievements in measuring the parameters distributing of two-phase flow. PT technique provides novel means of visualizing the internal behavior of industrial processes. The tomographic images produced by PT system provide valuable information for the assessment of equipment designs and the on-line monitoring of industrial processes.
Electrical Capacitance Tomography (ECT) is one of the techniques, which is firstly developed for PT. It has low-cost, high-speed, robust and non-intrusive. In this paper the ECT sensor structures and the data acquisitions system for ECT have been studied.
1 The sensor model was built by analyzing ECT sensor structure. To obtain the disciplinarian of configuration parameters and operation way to influence of ECT sensor performance by finite emulating. Configuration parameters and operation way included the electrode angle 0, the thickness of pipe wall (R2-R1), the relative permittivity value of pipe wall (epw), the thickness of screen layer (R3-R2), the relative permittivity value of screen layer (es), combined electrode and uncombined electrode and floating electrode and non-floating electrode. The configuration parameters of given pipe based on the disciplinarian.
2 The data acquisition system adopted the charge / discharge capacitance measuring circuit. This paper described the charge/discharge circuit and data acquisition. The data acquisition system used the DC offset compensation method to balance both the standing capacitance and the charge injection capacitance. To increase the overall data acquisition speed, parallel measurement channels were used. Because of wide dynamic range of measurement, a self-optimizing digital-control gain amplifier was presented to
satisfy the different sensitivity requirements. The gain amplifier also can increase the data acquisition speed at the same time. Lastly, the paper gave some suggestion for future study.
引文
[1] Beck M.S and Williams R.A: Process tomography: a European Innovation and its applications Meas. Sci.Technol.7 1996 215-224
[2] Zhu P, Duvauchelle P, Peix G and Babot D: X-ray Compton backscattering techniques for process tomography: imaging and characterization of materials Meas. Sci.Technol.7 1996 251-296
[3] Hoyle B.S: Progress tomography using ultrasonic sensors Meas. Sci.Technol.7 1996 272-250
[4] Brown G.J, Reilly D and Mills D: Development of an ultrasonic tomography system for application in pneumatic conveying Meas. Sci.Technol.7 1996 396-405
[5] 董琰婷，宏艺等．基于电磁感应原理的电磁成象系统的初步研究，见李海青、乔贺堂主编《多相流检测技术进展》，北京，石油工业出版社，1996，50-56
[6] 熊汗亮，董琰婷，王安文，徐苓安．电磁层析成象技术的物理机理和检测极限，天津大学学报，1998，31(2)，136-142
[7] 董峰，赵国勋，徐苓安．应用电阻层析成像技术测定两相流中气含率的研究，东北大学学报，2002，21，169-172
[8] Pinheiro P.A and Loh W.W et al. Smoothness-constrained inversion for two-dimensional electrical resistance tomography, Meas. Sci. Technol., 1997,8,293-302
[9] Ostrowski K.L,Luke S.P and Williams R.A: Application of conjugate harmonics to electrical process tomography. Meas. Sci.Technol.7 1996 316-324
[10] Dickin F and Wang M: Electrical resistance tomography for process applications. Meas.Sci.Technol.7 1996 247-260.
[11] Djamdji F, Gorvin A.C, Freeston I.L, Tozer R.C, Mayes I.C and Blight S.R: Electrical impedance tomography applied to semiconductor wafer
charaterization Meas. Sci.Tcchnol.7 1996 391-395
[12] Gupta D Sen S ndDas P.K: Finite difference resistance modelling for liqiud level measurement in stratified gas-liqiud systems. Meas. Sci.Tcchnol.5 1994 574-579
[13] Waterfall R.C, He R, White N.B and Beck C.M: Combustion imaging from electrical impedance measurcments.Mcas.Sci.Technol.7 1996 369-374
[14] LaBrecque D.J, Ramircz A.L, Daily W.D, Binlcy A.M and Schima S.A: ERT monitoring remediation processes. Meas. Sci.Technol.7 1996 375-383
[15] A Binlcy, B Shaw and S Henry-Poulter: Flow pathways in porous media: electrical resistance tomography and dye standing image verification. Mcas. Sci.Tcchnol.7 1996 384-390
[16] Dickin F and Wang M: Electrical resistance tomography for process applications. Meas. Sci.Technol.7 1996 247-260
[17] A J Peyon, Z Z Yu, G Lyon, S Al-Zeibak, J Fercira, J Velez, F Linhares, A R Borges, H L Xiong, N H Sauders M Wang: An overview of electromagnetic inductance tomography: description of three different systems Mcas. Sci.Technol.7 1996 261-271
[18] 王保良 乐嘉华 黄志尧：多相流参数检测电容层析成象技术研究 石油化工自动化 No．2 1998 4-6
[19] XIE C.G, Plaskowski a. and Beck M.S.: 8-electrode capacitance system for two-component flow identification. IEE. Proc. 1989(136) 173-190
[20] Beck M.S, Green R.G, Plaskolski A.B and Stott A.L : Capacitance measurement applied to a pneumatic conveyor with very low solids loading Meas. Sci.Technol. 1(1990)561-564
[21] Dickin.F.L, Hoyle.B.S, Hunt.A, Huang.S.M: Tomographic imaging of industrial process equipment: techniques and application. IEE PROC No.1 1992 72-82
[22] Xie.C.G, Huang.S.M, Hoyle.B.S, Thorn.R, Lenn.c: Electrical capacitance
tomography for flow imaging: system model for development of image reconstrution algorithms and design of primary sensors .IEE Proc No.1 1992 89-98
[23] 张宝芬，焦清，黄松明．电容式两相流相浓度传感器的仿真及优化．清华大学学报(自然科学版)，No．4，1992，25-31
[24] 许会．电容层析成象在气固两相流浓度测量中的应用技术研究，东北大学博士论文，1999
[25] 颜华．电容层析成象技术及在高炉块状区物料可视化检测的前期研究，东北大学博士论文，1999
[26] Yang W.Q: A self-balancing circuit to measure capacitance and loss conductance for industrial transducer application. IEEE Trans. Instum. Meas. Vo145,No.6 1996 955-958
[27] Yang W.Q: Hardware design of electrical capacitance tomography systems Meas. Sci.Technol.7 1996 225-232
[28] Yang W Q. Charge injection compensation for charge/discharge capacitance measuring circuit usedin tomography systems, Meas. Sci. Technol., 1996, 7, 1073-1078
[29] Xie.C.G, Stott.A.L, plaskowsk.A and Beck M.S: Design of capacitance electrodes for concentration measurement of two-phase flow. Meas.
[30] 胡之光主编．《电极电磁场的分析与计算》．机械工业出版社．1989．
[31] Johansen G A, Fraystein T, Hjertaker B.T and Olsen Q: A dual sensor flow imaging tomographic system Meas.Sci.Technol.7 1996 297-307
[32] Reinecke N and Mewes D: Recent developments and industrial-research applications of capacitance tomography. Meas. Sci. ,Technol.7 1996 233-246
[33] Hill M: Sensor update.: gas and liquid flow measurement. Meas. Sci.Technol. 5 (1990)836-838
[34] Yang W Q, Brant M. R. And Beck M S: A muti-interface level measurement system using a segmented capacitance sensor for oil separators Meas.Sci.Teehnol.5(1994) 1177-1180
[35] Kolle C and Leary P O: Low-cost, high-precision measurement system for capacitance sensors.Meas.Sci.Technol.9 1998 510-517
[36] Huang S M, Green R G, Plaskowsk A and Beck M S: A high frequency stray immune capacitance transducer based on the charge transfer principle. IEEE Trans. Instrum. Meas. No.3 1988 368-373.
[37] Yang W Q, Stoit A.L and Beck M S: High frequency and high resolution capacitance measuring circuit for process tomography, IEE Proc Circuit Device System (141).3 1994 215-219
[38] Tapson and Green J.R: Improved capacitance measurment by means of resonance locking. Meas. Sci. Technols (1994) 20-26
[39] Wang Huaxiang, Wuliang Yin , Yang W.Q and Beck M.S: Optimum design of segmented capacitance sensing array for multi-phase interface measurement Meas. Sci.Technol.7(1996) 71-86
[40] Huang S M, Xie C G, Thorn R, Snowden D, Beck M S: Design of sensor electronics for electrical capacitance tomography, IEE Proc No.1 1992 83-88
[41] Tapp H S, Kemsley E K, Wilson and Holley M L: Image improvement in soft-field tomography through the use of chemonetrics Meas. Sci. Technol.9 1998 592-598
[42] Isaksen Q: A review of reconstruction techniques for capacitance tomography. Meas. Sci.Technol.7 1996 325-337
[43] Oakley J.P and Bair M S: A mathematical model for the muti- electrode capacitance sensor. Meas. Sci.Technol.6(1995) 1617-1630
[44] 肖化 严杰 保宗悌：12电极电容层析成象的敏感场仿真研究仪器仪表学报 No．3 1998．
[45] Dyakowski T: Process. tomography applied to muti-phase flow measurement Meas. Sci.Technol.7 1996 343-353
[46] 颜华，王玉涛，邵富群，王师：电容传感器灵敏度分布快速计算法极其应用东北大学学报(自然科学版)(19)5 1998 505-508
[47] 余水宝等，高精度增益自寻优数控放大器及其应用研究，仪器仪表学
报，1999，20(6)：578～581
[48] 孟长虹等，并行处理提高测试分析仪器的动态范围和速度，仪器仪表学报，1998，19(3)
[49] 刘存编著《自动测试与应用系统》东北大学出版社 1994
[50] 胡汉才编著《单片机原理及接口技术》清华大学出版社1995
[51] 金喜平，郭雨梅等编著《智能仪器设计》辽宁科学技术出版社1994
[52] ANSYS入门手册(上-下)美国ANSYS公司北京办事处
[53] ANSYS电磁场分析指南ANSYS中国
[54] 蒋剑跃，石油多相流层析成象传感器及信号检测系统的研究．沈阳工业大学硕士论文，1999
[2] Zhu P, Duvauchelle P, Peix G and Babot D: X-ray Compton backscattering techniques for process tomography: imaging and characterization of materials Meas. Sci.Technol.7 1996 251-296
[3] Hoyle B.S: Progress tomography using ultrasonic sensors Meas. Sci.Technol.7 1996 272-250
[4] Brown G.J, Reilly D and Mills D: Development of an ultrasonic tomography system for application in pneumatic conveying Meas. Sci.Technol.7 1996 396-405
[5] 董琰婷，宏艺等．基于电磁感应原理的电磁成象系统的初步研究，见李海青、乔贺堂主编《多相流检测技术进展》，北京，石油工业出版社，1996，50-56
[6] 熊汗亮，董琰婷，王安文，徐苓安．电磁层析成象技术的物理机理和检测极限，天津大学学报，1998，31(2)，136-142
[7] 董峰，赵国勋，徐苓安．应用电阻层析成像技术测定两相流中气含率的研究，东北大学学报，2002，21，169-172
[8] Pinheiro P.A and Loh W.W et al. Smoothness-constrained inversion for two-dimensional electrical resistance tomography, Meas. Sci. Technol., 1997,8,293-302
[9] Ostrowski K.L,Luke S.P and Williams R.A: Application of conjugate harmonics to electrical process tomography. Meas. Sci.Technol.7 1996 316-324
[10] Dickin F and Wang M: Electrical resistance tomography for process applications. Meas.Sci.Technol.7 1996 247-260.
[11] Djamdji F, Gorvin A.C, Freeston I.L, Tozer R.C, Mayes I.C and Blight S.R: Electrical impedance tomography applied to semiconductor wafer
charaterization Meas. Sci.Tcchnol.7 1996 391-395
[12] Gupta D Sen S ndDas P.K: Finite difference resistance modelling for liqiud level measurement in stratified gas-liqiud systems. Meas. Sci.Tcchnol.5 1994 574-579
[13] Waterfall R.C, He R, White N.B and Beck C.M: Combustion imaging from electrical impedance measurcments.Mcas.Sci.Technol.7 1996 369-374
[14] LaBrecque D.J, Ramircz A.L, Daily W.D, Binlcy A.M and Schima S.A: ERT monitoring remediation processes. Meas. Sci.Technol.7 1996 375-383
[15] A Binlcy, B Shaw and S Henry-Poulter: Flow pathways in porous media: electrical resistance tomography and dye standing image verification. Mcas. Sci.Tcchnol.7 1996 384-390
[16] Dickin F and Wang M: Electrical resistance tomography for process applications. Meas. Sci.Technol.7 1996 247-260
[17] A J Peyon, Z Z Yu, G Lyon, S Al-Zeibak, J Fercira, J Velez, F Linhares, A R Borges, H L Xiong, N H Sauders M Wang: An overview of electromagnetic inductance tomography: description of three different systems Mcas. Sci.Technol.7 1996 261-271
[18] 王保良 乐嘉华 黄志尧：多相流参数检测电容层析成象技术研究 石油化工自动化 No．2 1998 4-6
[19] XIE C.G, Plaskowski a. and Beck M.S.: 8-electrode capacitance system for two-component flow identification. IEE. Proc. 1989(136) 173-190
[20] Beck M.S, Green R.G, Plaskolski A.B and Stott A.L : Capacitance measurement applied to a pneumatic conveyor with very low solids loading Meas. Sci.Technol. 1(1990)561-564
[21] Dickin.F.L, Hoyle.B.S, Hunt.A, Huang.S.M: Tomographic imaging of industrial process equipment: techniques and application. IEE PROC No.1 1992 72-82
[22] Xie.C.G, Huang.S.M, Hoyle.B.S, Thorn.R, Lenn.c: Electrical capacitance
tomography for flow imaging: system model for development of image reconstrution algorithms and design of primary sensors .IEE Proc No.1 1992 89-98
[23] 张宝芬，焦清，黄松明．电容式两相流相浓度传感器的仿真及优化．清华大学学报(自然科学版)，No．4，1992，25-31
[24] 许会．电容层析成象在气固两相流浓度测量中的应用技术研究，东北大学博士论文，1999
[25] 颜华．电容层析成象技术及在高炉块状区物料可视化检测的前期研究，东北大学博士论文，1999
[26] Yang W.Q: A self-balancing circuit to measure capacitance and loss conductance for industrial transducer application. IEEE Trans. Instum. Meas. Vo145,No.6 1996 955-958
[27] Yang W.Q: Hardware design of electrical capacitance tomography systems Meas. Sci.Technol.7 1996 225-232
[28] Yang W Q. Charge injection compensation for charge/discharge capacitance measuring circuit usedin tomography systems, Meas. Sci. Technol., 1996, 7, 1073-1078
[29] Xie.C.G, Stott.A.L, plaskowsk.A and Beck M.S: Design of capacitance electrodes for concentration measurement of two-phase flow. Meas.
[30] 胡之光主编．《电极电磁场的分析与计算》．机械工业出版社．1989．
[31] Johansen G A, Fraystein T, Hjertaker B.T and Olsen Q: A dual sensor flow imaging tomographic system Meas.Sci.Technol.7 1996 297-307
[32] Reinecke N and Mewes D: Recent developments and industrial-research applications of capacitance tomography. Meas. Sci. ,Technol.7 1996 233-246
[33] Hill M: Sensor update.: gas and liquid flow measurement. Meas. Sci.Technol. 5 (1990)836-838
[34] Yang W Q, Brant M. R. And Beck M S: A muti-interface level measurement system using a segmented capacitance sensor for oil separators Meas.Sci.Teehnol.5(1994) 1177-1180
[35] Kolle C and Leary P O: Low-cost, high-precision measurement system for capacitance sensors.Meas.Sci.Technol.9 1998 510-517
[36] Huang S M, Green R G, Plaskowsk A and Beck M S: A high frequency stray immune capacitance transducer based on the charge transfer principle. IEEE Trans. Instrum. Meas. No.3 1988 368-373.
[37] Yang W Q, Stoit A.L and Beck M S: High frequency and high resolution capacitance measuring circuit for process tomography, IEE Proc Circuit Device System (141).3 1994 215-219
[38] Tapson and Green J.R: Improved capacitance measurment by means of resonance locking. Meas. Sci. Technols (1994) 20-26
[39] Wang Huaxiang, Wuliang Yin , Yang W.Q and Beck M.S: Optimum design of segmented capacitance sensing array for multi-phase interface measurement Meas. Sci.Technol.7(1996) 71-86
[40] Huang S M, Xie C G, Thorn R, Snowden D, Beck M S: Design of sensor electronics for electrical capacitance tomography, IEE Proc No.1 1992 83-88
[41] Tapp H S, Kemsley E K, Wilson and Holley M L: Image improvement in soft-field tomography through the use of chemonetrics Meas. Sci. Technol.9 1998 592-598
[42] Isaksen Q: A review of reconstruction techniques for capacitance tomography. Meas. Sci.Technol.7 1996 325-337
[43] Oakley J.P and Bair M S: A mathematical model for the muti- electrode capacitance sensor. Meas. Sci.Technol.6(1995) 1617-1630
[44] 肖化 严杰 保宗悌：12电极电容层析成象的敏感场仿真研究仪器仪表学报 No．3 1998．
[45] Dyakowski T: Process. tomography applied to muti-phase flow measurement Meas. Sci.Technol.7 1996 343-353
[46] 颜华，王玉涛，邵富群，王师：电容传感器灵敏度分布快速计算法极其应用东北大学学报(自然科学版)(19)5 1998 505-508
[47] 余水宝等，高精度增益自寻优数控放大器及其应用研究，仪器仪表学
报，1999，20(6)：578～581
[48] 孟长虹等，并行处理提高测试分析仪器的动态范围和速度，仪器仪表学报，1998，19(3)
[49] 刘存编著《自动测试与应用系统》东北大学出版社 1994
[50] 胡汉才编著《单片机原理及接口技术》清华大学出版社1995
[51] 金喜平，郭雨梅等编著《智能仪器设计》辽宁科学技术出版社1994
[52] ANSYS入门手册(上-下)美国ANSYS公司北京办事处
[53] ANSYS电磁场分析指南ANSYS中国
[54] 蒋剑跃，石油多相流层析成象传感器及信号检测系统的研究．沈阳工业大学硕士论文，1999