FBG Temperature and Pressure Sensing System for Hot Water Pipeline of Petrochemical Factory

496JOURNAL OF ELECTRONIC SCIENCE AND TECHNOLOGY OF CHINA, VOL 6, NO.4. DECEMBER 2008FBG Temperature and Pressure Sensing System forHot Water Pipeline of Petrochemical FactoryGuo-Hui La, Shao-Hua Shang, Xu Jjiang, Jjn-Ping Ou, Chao Yang, Chuan-Di Li, and Wei XuAbstract- A spatial and wavelength division multi-In this paper, we show a distributed fiber sensor systemplexing fiber Bragg grating (FBG) sensing system isfor measuring the temperature and pressure of hot pipelinereported for monitoring the temperature and thein petrochemical factory.pressure (T-P) of hot water pipeline in petrochemicalfactory. The FBG sensing system has 72 channels2. Experiment Setupindependently, and it provides the capability to monitorThere are 72 points needed to monitor in thelarge number sensors at same time. A resolution oftemperature and pressure monitoring project, and the0.1 °C and 0.01 MPa with a measurement bandwidth ofsensors are distributed in 2 km area. For this muti-point150 Hz has been achieved.detection, we use a tunable fber laser as the light source toIndex Terms- -FBG sensor, sensing net, temperatureprovide higher light intensity, so the sensor system canand pressure sensors, tunable laser.obtain high signal-to-noise ratio. The basic confguration ofthe sensing system is shown in Fig.1.BGI FBO2 FBOCoupler1. Introduction' fiber lae ,Recently, fiber Bragg gratings (FBGs) has attractedWovelene cllbntionCouplrincreasing attentions for its potential applications infiber- optic sensorslU-6], optical communication systems",optical switching and optical signal processing's. Becauseof their inherent wavelength-encoded operation, FBGs arexbsuitable for their application as sensing elements for网tmeasure temperature, pressure, and strain in remote areas toprovide early warning for hazardous situations, such asnernetAMPpetrochemical and civil. How to interrogate the FBGsensors is the key problem for using the FBG sensor. ManyPCstudies have been done to achieve this goal and severalmeans have been proposedlHo. As we know that the bestdemodulation method is not only to achieve the precision ofFig.1. The scheme of distributed temperature and pressurethe phase demodulation, but also have the compactmeasurement system.structure and low-cost of the light intensity demodulation,The tunable ring cavity laser uses the fiber Fabry-Perotand it is easy to process the signal and expand the sensorinterferometer (FFPI) and the piezoelectric translator (PZT)channelwhich is attached with a controllable element. Theoutput-wavelength fom the fber laser is tuned by adjustingManuseript reeived September 18, 2008; revised October 20, 2008. the tuning voltage on PZT, and thus induces a shift ofThis work was supported by Key Projects the National Natural Sciencewavelength of laser. The output light, scanning inFoundation of China under Grant No. 50538020, the Educationwavelength, is transferred through a coupler array to theDepartment Science Foundation of Heilongjiang Province under Grant No.11521211, and the Technology Department Science Foundation ofFBG sensor. The light signal reflected from the sensor isHeilongjiang Province under Grant No. GC07A506.lunched into the PIN array to be detected.G.H. Lo, S.-H. Shang, X Jiang, C. Yang, C.-D. Li, and W. Xu are withThere are three FBGs in the sensor, as show in Fig. 2,School of. Electeronic Engineering. Heilongiang University, Hartinoneerature, and the other150080, China (e mail: lvguohui@hlju edu.cn).中国煤化工J-P. Ou is with School of Civil Enginering Harbin Intite ofFBGsssure parameter. ToTechnology, Harbin 150090, China and Dalian University of Tchnology, reducYHC N M H Gsor was designed asDalian, 116024, China.single fiber pigtail output. So the style of sensor net is in97parallel, not series. We use fiber coupler splitter to expand mega internet interface. The data are stored in the disk,the numbers of sensing channel. Finally a 72-channel displayed on the screen or printed. The software is writtendistributed temperature-pressure sensing system is by use of Labview. The interface of the data processestablished.software is shown in Fig. 5 and Fig. 6.FBGpress scrsotemperaturesensFig. 5. The interface of temperature data.b)Fig. 2. The temperature-pressure FBG sensor: (a) the outine ofT-P FBG sensor and (b) the photo of the T-P FBG sensor.The sensor is fixed at the specified place of the hotwater pipeline, as seen in Fig. 3. The sensing signal istransmitted to the FBG sensor demodulator through fibercable. The longest cable is much more than 2 km.Fig. 6. The interface of pressure data.3. Measurement ResultIf the sensor is connccted to the instrument, thecharacteristic curve of the pressure sensor can be measured.When the pressure on the FBG sensor increases (0Fig. 3. The fixing position of the T-P sensor.decreases), the corresponding experimental hysteresis canAll these 72 sensors are conected to access box. Every be obtained. The curve is shown in Fig. 7. It is a linearchannel of the box is corresponding to a T-P sensor, The relation between pressure and the center wavelength of thedemodulator is shown in Fig. 4.FBG sensor.1535.61535.4Fig. 4. FBG sensor demodulator: (a) front view and (b) rear view.中国煤化工_The T-P sensing signal is demodulated by the instument,CNMHGa).2.0 25the wavelength is converted into temperature and pressuremessage. The parameter is transmitted to PC through 10 Fig. 7. The charateristic curve of hot water pressure sensor.498 .JOURNALOF ELECTRONIC SCIENCE AND TECHNOLOGY OF CHINA, VOL. 6, NO.4, DECEMBER 20084. Conclusionsintrferometer by use of a tunable fiber lase," IEEEPhotonics Technology Letters, vol. 17, no. 5, pp. 1061-1063,A multi-points T-P sensor demodulation technique2005.based on a tunable fiber laser is achieved. The temperatureand pressure FBG sensor is special designed and made. TheGuo-Hui LQ was bom in Heilongjiang Province, China, inadvantages of this system include high signal-to-noise ratio,1972. He received the B.S. and the M.S. degrees both in electricallow cost, remote monitoring, environmental stability and eninering fom the Heilogiang University, Harbin, in 1995higher accuracy measurements. This system can be used inand 1999, respectively. He received the Ph.D. degree fromsome harsh environments. For example, it bas a greatDepartment of Physics of Harbin Institute of Technology (HIT) inapplication value for the temperature and pressure2005. He worked as postdoctor with School of Civil Engineeringof HIT until November 2007. His research interest is in opticalmeasurement in petrochemical factory.fiber sensing.Shao-Hua Shang was borm in Heilongjiang Province, China,in 1982. He received the B.S. and the M.S. degrees both inelectrical engineering from the Heilogiang University Harbin,Referencesin 2005 and 2008, respectively. His research interest is in optical[1] A. D. Kersey and M. A. Davis, "Fiber grating sensors," J.Lightwave Technology, vol. 15, no. 8, pp. 1442-1463, 1997.Xu Jiang was bormn in Hilongiang Province, China, in 1974.[2] T. A. Berkf and A. D. Kersey, Fiber Bragg grating arrayShe received the B.S. degrees in computer science from thesensor system using a bandpass wavelength divisionHeilongiang University, Harbin, in 1999. Her research interest ismultiplexer and interferometric detection," IEEE Phtonicsin computer technology.Technology Letters, vol. 8, no. 11, pp. 1522-1524, 1996.Jin-Ping Ou was borm in Hunan Province, China, in 1959.3] M. A. Davis, D. G Bellemore. M. A. Putnam, and A. D.He received his Ph.D. degree in 1987 fom Harbin Institute ofKersey,“A 60 element fber Bragg grating sensor system," inTechnology, China. In 2003, be was elected as a member ofProc. l1th Intermational Conference on Optical Fiber Sensors, Chinese Academy of Engineering. From 1991 to 2006, he was aSapporo, Japan, 1996, pp. 100-103.professor and the Vice-President at HIT. In 2006, he became the4] Y.-J. Rao, A. B. Lobo Ribeiro, and D. A. Jackson,“Combinedpresident and a professor at Dalian University of Technology,spatialand time division-mutiplexing scheme for fberChina. His main research interests include structural damage,grating sensors with drift. compensated pbase-sensitive relibility and health monitoring, structural vibration and control,detection," Opt. Lett, vol. 20, no. 20, pp. 2149-2151, 1995.and smart material and structures.[5] A. D. Kersey, T. A. BerkofT and W. W. Morsey,“MultiplexedChao Yang was borm in Heilongjiang Province, China, infiber Bragg grating strain-sensor system with a fber1982. He received the B.S. and the M.S. degrees both in electricalFabry-Perot wavelength filter," Opt. Lett, vol. 18, no. 16,eagineering from the Heilogjiang University, Harbin, in 2005pp. 1370-1372, 1993.and 2008, respectively. His research interest is in optical fber[6] Y:-J. Rao, A.B. Lobo Riberio, D.A. Jackson, L. Zhang, and I.sensing.Bennion,“Simultaneous spatial, time and wavelength divisionChuan-Di Li was bom in Heilongjiang Province, China, inmultiplexed in-fber grating sensing network," Opt. Commun,1982. She received the B.S. and the M.S. degrees both in electricalvol. 125, no. 1, pp.53-58, 1996.engineering from the Heilongjiang University, Harbin, in 2005[7] B. Ortega, J. Capmany, and J. L. Cruz,“Wavelength divisionnd 2008, respectively. Her research interest is in optical fbermultiplexing al-iber bhybrid devices based on Fabry-Perot'sand gratings," J. Lightwave Technology, vol. 17, no. 7, pp.Wei Xu was bom in Heilongjiang Province, China, in 1979.1241-1247, 1999.He received the B.S. degrees both in computer science from the[8] G.-H. Lo, H.-A. Ye, J-Q. Li, X.~D. Sun, and X.-M. Zhang,Heilongjiang University, Harbin, in 2002. His research interest isHybrid optical spectral bistability in fber Michelsonin optical fber sensing.中国煤化工MYHCNMHG