测量液位的波纹膜片式光纤Bragg光栅压力传感器
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摘要
液位测量传感器作为自动控制、计量的重要核心元件被大量应用在石化等工业领域,以保证生产过程各环节中液位的平衡并为进行经济核算提供可靠的依据；维持正常生产、保证产品的产量和质量、以及保证安全生产具有重要的意义。
易燃液体,如汽油等,通常是被储藏在高度为几十米以下的密闭容器中,如何安全并可靠的测量出密闭容器中的易燃液体液位一直是石化行业的重点问题。上述密闭容器中的易燃液体,其对容器底部所产生的压强通常为几个兆帕。目前国内外对于易燃液体液位测量的液位传感器,一般都是电学传感器。这类传感器虽然测量水平已达到较高的自动化程度和测量精度,但上述方法大都采用电激励和电信号传输,在测量易燃液体时极易因火花放电而引起火灾或爆炸,即使采用防爆处理过的本安传感器也还是存在有一定的风险,且价格较高并较难形成测量网络。
光纤Bragg光栅传感技术是一种新型的传感技术,通过Bragg波长的漂移来获得诸如应力、温度、振动、加速度等外部参量,由于它的测量手段和传输途径都为光信号,因此具有不受环境的电磁干扰、本安等优点,能够极大地提高测量的安全性和可靠性。因而在测量易燃液体液位领域中,光纤Bragg光栅传感器具有广阔的应用前景。本课题采用光纤Bragg光栅作为敏感元件,对其用于液位测量的相关理论和技术进行了一系列理论分析和实验研究。
针对现有条件,选择低压作为实验研究对象,并采用较为简单的压力法测量方式,以便掌握传感数学模型在实际测量中的特点,并提出相应的改进方案。后期依据实验验证的传感数学模型原理,改变换能元件的材料和尺寸来达到增大测量对象量程的目的。目前通过理论分析与实验研究已完成了以下主要工作：
1、基于膜片中心挠度变化与所受压强呈线性关系；基于粘贴在等强度悬臂梁上的光纤Bragg光栅其波长波变化与悬臂梁所受应力呈线性关系等理论建立了传感模型,设计了测量液位的光纤Bragg光栅压力传感器；
2、根据所选材料及其尺寸计算出该传感器的理论灵敏度。理论灵敏度为7pm/cm；理论分别率为：0.14cm/pm。
3、通过实验的方式,测量出了实际灵敏度为：加载4.9pm/cm,卸载5.4pm/cm；实际分辨率为：0.20cm/pm；
4、实验结果表明Bragg波长漂移值与液位变化量呈较好的线性关系,实验证明了该传感器的设计是可行的,这为后期传感器的实用化研究提供了良好的开端。
The liquid level measurement as the automatic control and measurement important core part is applied massively in the industry field such as petrifaction in order to make sure the balance of the liquid level in each production process, and provide the reliable basis of economic accounting. It also has important significance in maintaining the regular production, ensuring yield and quality of production.
Flammable liquid, such as gasoline etc, usually is preserved in sealed container of dozens of height. How to secure and reliable measurement the liquid level in the sealed container has been a important problem in petrifaction field. The flammable liquid in sealed container usually produces several million PA pressure for the bottom of container. At present, it usually use electricity sensor to measure the level of flammable liquid at home and abroad. This class sensor measurement standard has reached a higher degree of automation and definition. By using electric Power and electric transmission, this sensor is easily caused fire or explosion when measure flammable liquid. Even if it has been processed for avoid explosion which also has some risks. And it also has high price and very difficult to make measurement net.
Fiber Bragg grating sensor is a new sensing technology. Obtain such as pressure, temperature, vibration, acceleration etc external parameters by the shift of Bragg wavelength. Because its measuring means and transferring process is optical signal, its Advantages is that it has no electromagnetic interference by the environment and intrinsic safe which could highly improve security and reliability of the measurement. So in the field of the liquid level measurement of flammable liquid, the fiber Bragg grating has wide application prospect. This topic use fiber Bragg grating as sensitive element to do a series of theories analysis and experimental research for related theories and technology of the liquid level measurement.
Based on current condition, I select the low pressure as research object, and use relatively easyly pressure method as measurement method in order to grasp the characteristic of sensing mathematical model in practical measurement, and then give corresponding improvement method. Later, I could based on the principle of sensing mathematical model which improved by experimental verification to change material and size of sensitive elements to do the purposes of increasing range of measurement object. Now, I have done the following main work by theoretical analysis and experimental research:
1. Established the sensing model based on the central deflections of the shell petal of diaphragm has a linear relation with compression press, based on changing wavelength of fiber Bragg grating pasting on the cantilever beam has a linear relation with pressure of cantilever beam, and then design a fiber Bragg grating pressure sensor using for measurement liquid level.
2. According to materials and size I have calculated the theory sensitivity of this sensor. The theory sensitivity is 7pm/cm, the theory resolution is 0.14cm/pm.
3. By experiment method, obtain the actual sensitivity, loading 4.9pm/cm, unloading 5.4pm/cm. The actual resolution is 0.20cm/pm.
4. The results show that the shift of Bragg wavelength has a good linear relation with changing of liquid level. The experiment confirmed that the design of this fiber Bragg grating pressure sensor is feasible. It provides a good beginning for later sensor's practical research.
易燃液体,如汽油等,通常是被储藏在高度为几十米以下的密闭容器中,如何安全并可靠的测量出密闭容器中的易燃液体液位一直是石化行业的重点问题。上述密闭容器中的易燃液体,其对容器底部所产生的压强通常为几个兆帕。目前国内外对于易燃液体液位测量的液位传感器,一般都是电学传感器。这类传感器虽然测量水平已达到较高的自动化程度和测量精度,但上述方法大都采用电激励和电信号传输,在测量易燃液体时极易因火花放电而引起火灾或爆炸,即使采用防爆处理过的本安传感器也还是存在有一定的风险,且价格较高并较难形成测量网络。
光纤Bragg光栅传感技术是一种新型的传感技术,通过Bragg波长的漂移来获得诸如应力、温度、振动、加速度等外部参量,由于它的测量手段和传输途径都为光信号,因此具有不受环境的电磁干扰、本安等优点,能够极大地提高测量的安全性和可靠性。因而在测量易燃液体液位领域中,光纤Bragg光栅传感器具有广阔的应用前景。本课题采用光纤Bragg光栅作为敏感元件,对其用于液位测量的相关理论和技术进行了一系列理论分析和实验研究。
针对现有条件,选择低压作为实验研究对象,并采用较为简单的压力法测量方式,以便掌握传感数学模型在实际测量中的特点,并提出相应的改进方案。后期依据实验验证的传感数学模型原理,改变换能元件的材料和尺寸来达到增大测量对象量程的目的。目前通过理论分析与实验研究已完成了以下主要工作：
1、基于膜片中心挠度变化与所受压强呈线性关系；基于粘贴在等强度悬臂梁上的光纤Bragg光栅其波长波变化与悬臂梁所受应力呈线性关系等理论建立了传感模型,设计了测量液位的光纤Bragg光栅压力传感器；
2、根据所选材料及其尺寸计算出该传感器的理论灵敏度。理论灵敏度为7pm/cm；理论分别率为：0.14cm/pm。
3、通过实验的方式,测量出了实际灵敏度为：加载4.9pm/cm,卸载5.4pm/cm；实际分辨率为：0.20cm/pm；
4、实验结果表明Bragg波长漂移值与液位变化量呈较好的线性关系,实验证明了该传感器的设计是可行的,这为后期传感器的实用化研究提供了良好的开端。
The liquid level measurement as the automatic control and measurement important core part is applied massively in the industry field such as petrifaction in order to make sure the balance of the liquid level in each production process, and provide the reliable basis of economic accounting. It also has important significance in maintaining the regular production, ensuring yield and quality of production.
Flammable liquid, such as gasoline etc, usually is preserved in sealed container of dozens of height. How to secure and reliable measurement the liquid level in the sealed container has been a important problem in petrifaction field. The flammable liquid in sealed container usually produces several million PA pressure for the bottom of container. At present, it usually use electricity sensor to measure the level of flammable liquid at home and abroad. This class sensor measurement standard has reached a higher degree of automation and definition. By using electric Power and electric transmission, this sensor is easily caused fire or explosion when measure flammable liquid. Even if it has been processed for avoid explosion which also has some risks. And it also has high price and very difficult to make measurement net.
Fiber Bragg grating sensor is a new sensing technology. Obtain such as pressure, temperature, vibration, acceleration etc external parameters by the shift of Bragg wavelength. Because its measuring means and transferring process is optical signal, its Advantages is that it has no electromagnetic interference by the environment and intrinsic safe which could highly improve security and reliability of the measurement. So in the field of the liquid level measurement of flammable liquid, the fiber Bragg grating has wide application prospect. This topic use fiber Bragg grating as sensitive element to do a series of theories analysis and experimental research for related theories and technology of the liquid level measurement.
Based on current condition, I select the low pressure as research object, and use relatively easyly pressure method as measurement method in order to grasp the characteristic of sensing mathematical model in practical measurement, and then give corresponding improvement method. Later, I could based on the principle of sensing mathematical model which improved by experimental verification to change material and size of sensitive elements to do the purposes of increasing range of measurement object. Now, I have done the following main work by theoretical analysis and experimental research:
1. Established the sensing model based on the central deflections of the shell petal of diaphragm has a linear relation with compression press, based on changing wavelength of fiber Bragg grating pasting on the cantilever beam has a linear relation with pressure of cantilever beam, and then design a fiber Bragg grating pressure sensor using for measurement liquid level.
2. According to materials and size I have calculated the theory sensitivity of this sensor. The theory sensitivity is 7pm/cm, the theory resolution is 0.14cm/pm.
3. By experiment method, obtain the actual sensitivity, loading 4.9pm/cm, unloading 5.4pm/cm. The actual resolution is 0.20cm/pm.
4. The results show that the shift of Bragg wavelength has a good linear relation with changing of liquid level. The experiment confirmed that the design of this fiber Bragg grating pressure sensor is feasible. It provides a good beginning for later sensor's practical research.
引文
[1]秦永烈编.物位测量仪表,北京：机械工业出版社,1978
[2]刘自放,刘春蕾.热工检测与自动化控制,北京：中国电力出版社,2007
[3]孙圣和,王延云等.光纤测量传感技术.哈尔滨工业大学出版社.2000.1
[4]Hill K O,Fujii Y, Johnson D C,Kawasaki B S.Photosensitivity in Optical Fiber Waveguides: Application to Reflection Filter Fabrication, Applied Physics Letters,1978,32(10):647～649
[5]Hill, K.O. Meltz. Gerald Fiber Bragg grating technology fundamentals and overview.J. Lightwave Technol.,1997,(15):1263-1276
[6]Meltz, G. Morey W W, Glenn W H. Formation of Bragg gratings in optical fibers by a transverses Holographic method.Opt.Left.,1989,(14):823-825
[7]李川,张以谟,赵永贵,李立京.光纤光栅：原理、技术与传感应用,北京：科学出版社,2005
[8]Hill K O,Malo B, Bilodeau F etal. Bragg Gratings Fabricated in Monomode Photosensitive Optical Fiber by UV Exposure Thorough a Phase Mask,Applied Physics Letters,1993,62:1035～1037
[9]Erdogan T. Fiber Grating Spectra, IEEE Journal of Lightwave Technology,1997,15:1277-1294.
[10]ZHANG S L, LEE S B, XIE F. In-fiber grating sensors [J]. Optics Laser Engineering,1999, 32:405-418.
[11]SCHROEDER R J, YAMATE T, UDD E. High temperature and pressure sensing for the oil industry using fiber Bragg gratings written onto side hole single mode fiber [J]. SPIE,1999,3745:42-48.
[12]LEE Y W, LEE B. High resolution cryogenic optical fiber sensor system using erbium-doped fiber [J].Sensors and Actuators,2002, A96:25-27.
[13]SHU X W, LIU Y. Dependence of temperature and strain coefficients on fiber grating type and its application to simultaneous temperature and strain measurement [J]. Opt Lett,2002, 27 (9):701-703.
[14]BUTOV O V, CGLANT K M. Ultra-thermo-resistant Bragg gratings written in nitrogen -doped silica fibers [J]. Electron Lett,2002,38 (11):523-525.
[15]FORKINE M. High temperature resistant Bragg gratings fabricated in silica optical fibers [A]. Australian Conference on Optical Fiber Technology [C]. Queensland:Proc ACOFT96,1996: 1325-1330.
[16]靳伟,廖延彪,张志鹏等.导波光学传感器：原理与技术,北京：科学出版社,1998
[17]徐开先.波纹管类组件的制造及其应用,北京：机械工业出版社,1998
[18]翁善臣等编.仪表弹性元件设计基础,北京：机械工业出版社,1982
[19]樊大钧.波纹管设计学.北京：北京理工大学出版社,1988
[20]刘广玉等.仪表弹性元件.北京：国防工业出版社,1982
[21][俄]安德列娃主编,翁善臣等译.波纹管的计算与设计,北京：国防工业出版社,1982
[22]竺培国.精密仪器结构设计基础(下册),哈尔滨：哈尔滨工业大学出版社,1998
[23]付宝连.弯曲薄板功的互等新理论.北京：科学出版社,2003
[24]王龙甫.弹性理论,北京：科学出版社,1984
[25]吴毓熙.应用弹性力学,上海：同济大学出版社,1989
[26]徐芝纶.弹性力学(F册),北京：高等教育出版社(第二版),1982
[27]樊大钧,刘广玉.新型弹性敏感元件设计,北京：国防工业出版社,1995
[28]杨桂通.弹性力学,北京：高等教育出版社,1998
[29]李同林.应用弹性力学,武汉：中国地质大学出版社,2002
[30]单辉祖.材料力学,北京：高等教育出版社,1999
[31]赵勇等.光纤光栅及其传感技术,北京：国防工业出版社,2007
[32]杨佰源,张义同.工程弹塑性力学,北京：机械工业出版社,2003
[33]刘常满.热工检测技术,北京：中国计量出版社,2005
[34]刘湘秋编著.常用压力容器,北京：机械工业出版社,2004
[35]王永红等.过程检测仪表,北京：化学工业出版社,1999
[36]姜德生,何伟.光纤光栅传感器的应用概况,光电子激光2002,13(4)：420-430
[37]Measure R M. Advances Towords Fiber Optic Based Smart Structure. OpticalEngineering, 1992,31(1):34-47.
[38]HUANG Y L, LI J,KAI G Y et al. Temperature and compensation package for fiber Bragg gratings [J]. Microwave and Optical Technology Letters,2003,39(1):70-72.
[39]Teunissen J, Helming C, Merte R, Peier D. Optical On-Line Monitoring for High-Voltage Transformers, SPIE,2001,4204:198～205
[40]Internet reference:dot.gov/onedot/library/tech-share/flagbg.cfm
[41]Lin Y B, Chang K C, Chern J C et al. The Health Monitoring of a Prepressureed Concrete Beam by Using Fiber Bragg Grating Sensors, Smart Materials and Structures,2004,13(4): 712-718.
[42]Bjerkan L. Application of Fiber-Optic Bragg Grating Sensors in Monitoring Environmental Loads of overhead Power Transmission Lines, Applied Optics,2000,39 (4):554～560
[43]樊尚春.传感器技术及应用,北京：北京航空航天大学出版社,2004
[2]刘自放,刘春蕾.热工检测与自动化控制,北京：中国电力出版社,2007
[3]孙圣和,王延云等.光纤测量传感技术.哈尔滨工业大学出版社.2000.1
[4]Hill K O,Fujii Y, Johnson D C,Kawasaki B S.Photosensitivity in Optical Fiber Waveguides: Application to Reflection Filter Fabrication, Applied Physics Letters,1978,32(10):647～649
[5]Hill, K.O. Meltz. Gerald Fiber Bragg grating technology fundamentals and overview.J. Lightwave Technol.,1997,(15):1263-1276
[6]Meltz, G. Morey W W, Glenn W H. Formation of Bragg gratings in optical fibers by a transverses Holographic method.Opt.Left.,1989,(14):823-825
[7]李川,张以谟,赵永贵,李立京.光纤光栅：原理、技术与传感应用,北京：科学出版社,2005
[8]Hill K O,Malo B, Bilodeau F etal. Bragg Gratings Fabricated in Monomode Photosensitive Optical Fiber by UV Exposure Thorough a Phase Mask,Applied Physics Letters,1993,62:1035～1037
[9]Erdogan T. Fiber Grating Spectra, IEEE Journal of Lightwave Technology,1997,15:1277-1294.
[10]ZHANG S L, LEE S B, XIE F. In-fiber grating sensors [J]. Optics Laser Engineering,1999, 32:405-418.
[11]SCHROEDER R J, YAMATE T, UDD E. High temperature and pressure sensing for the oil industry using fiber Bragg gratings written onto side hole single mode fiber [J]. SPIE,1999,3745:42-48.
[12]LEE Y W, LEE B. High resolution cryogenic optical fiber sensor system using erbium-doped fiber [J].Sensors and Actuators,2002, A96:25-27.
[13]SHU X W, LIU Y. Dependence of temperature and strain coefficients on fiber grating type and its application to simultaneous temperature and strain measurement [J]. Opt Lett,2002, 27 (9):701-703.
[14]BUTOV O V, CGLANT K M. Ultra-thermo-resistant Bragg gratings written in nitrogen -doped silica fibers [J]. Electron Lett,2002,38 (11):523-525.
[15]FORKINE M. High temperature resistant Bragg gratings fabricated in silica optical fibers [A]. Australian Conference on Optical Fiber Technology [C]. Queensland:Proc ACOFT96,1996: 1325-1330.
[16]靳伟,廖延彪,张志鹏等.导波光学传感器：原理与技术,北京：科学出版社,1998
[17]徐开先.波纹管类组件的制造及其应用,北京：机械工业出版社,1998
[18]翁善臣等编.仪表弹性元件设计基础,北京：机械工业出版社,1982
[19]樊大钧.波纹管设计学.北京：北京理工大学出版社,1988
[20]刘广玉等.仪表弹性元件.北京：国防工业出版社,1982
[21][俄]安德列娃主编,翁善臣等译.波纹管的计算与设计,北京：国防工业出版社,1982
[22]竺培国.精密仪器结构设计基础(下册),哈尔滨：哈尔滨工业大学出版社,1998
[23]付宝连.弯曲薄板功的互等新理论.北京：科学出版社,2003
[24]王龙甫.弹性理论,北京：科学出版社,1984
[25]吴毓熙.应用弹性力学,上海：同济大学出版社,1989
[26]徐芝纶.弹性力学(F册),北京：高等教育出版社(第二版),1982
[27]樊大钧,刘广玉.新型弹性敏感元件设计,北京：国防工业出版社,1995
[28]杨桂通.弹性力学,北京：高等教育出版社,1998
[29]李同林.应用弹性力学,武汉：中国地质大学出版社,2002
[30]单辉祖.材料力学,北京：高等教育出版社,1999
[31]赵勇等.光纤光栅及其传感技术,北京：国防工业出版社,2007
[32]杨佰源,张义同.工程弹塑性力学,北京：机械工业出版社,2003
[33]刘常满.热工检测技术,北京：中国计量出版社,2005
[34]刘湘秋编著.常用压力容器,北京：机械工业出版社,2004
[35]王永红等.过程检测仪表,北京：化学工业出版社,1999
[36]姜德生,何伟.光纤光栅传感器的应用概况,光电子激光2002,13(4)：420-430
[37]Measure R M. Advances Towords Fiber Optic Based Smart Structure. OpticalEngineering, 1992,31(1):34-47.
[38]HUANG Y L, LI J,KAI G Y et al. Temperature and compensation package for fiber Bragg gratings [J]. Microwave and Optical Technology Letters,2003,39(1):70-72.
[39]Teunissen J, Helming C, Merte R, Peier D. Optical On-Line Monitoring for High-Voltage Transformers, SPIE,2001,4204:198～205
[40]Internet reference:dot.gov/onedot/library/tech-share/flagbg.cfm
[41]Lin Y B, Chang K C, Chern J C et al. The Health Monitoring of a Prepressureed Concrete Beam by Using Fiber Bragg Grating Sensors, Smart Materials and Structures,2004,13(4): 712-718.
[42]Bjerkan L. Application of Fiber-Optic Bragg Grating Sensors in Monitoring Environmental Loads of overhead Power Transmission Lines, Applied Optics,2000,39 (4):554～560
[43]樊尚春.传感器技术及应用,北京：北京航空航天大学出版社,2004