HAZARD MONITORING IN MINES USING FIBER OPTIC SENSORS

Transcription

1 HAZARD MONITORING IN MINES USING FIBER OPTIC SENSORS T. Liu, C. Wang, Y. Wei, Y. Zhao, Y. Shang Laser Inst. Shandong Academy of Science, China D. Huo, Z Wang Yanong Ning Intelligent Sensor Systems Ltd. UK Presentation: S&A IOP and OFS-20, Edinburgh

2 OUTLINE Background - Mine Hazards FOS based Intelligent Mine Safety Monitoring Systems Roof condition and water burst monitoring Early fire detection Power safety monitoring Spontaneous fire early warning Methane gas monitoring Field trials: coal mines, tailings dam landslide Summary 2

3 CHINESE COAL MINE INDUSTRY Coal provides majority of the energy (>70%); Annual Production: ~3 billion tons, ~ 1/3 of world coal production; Number of coal mines: ~15,000 - State and local government own ~3,000, the rests are small mines; Used to be >70,000 mines Key Issue: SAFETY 3

4 COAL MINE SAFETY : Number of coal mine accidents:18,516 Number of death: 31,064 (AVE: 17 per day!) In recent years, both the government and the mine operators invested heavily on safety technologies, the fatality rate dropped, but total number still very high. FATALITIES DUE TO EXPLOSION: State owned mine groups have world class safety standard; However, in small mines casualty rate over 100 times higher. 4

5 MAJOR COAL MINE HAZARDS 2006 Jan-Oct: Fatalities GAS OUTBURST ROOF 346 Flooding Methane explosion WATER TRANSPORT Roof collapse, rock & coal outburst FIRE 1615 BLASTERS 5

6 MOTIVATION To develop a comprehensive mine disaster management system based on fiber optic sensor network, Capable of mining hazard early warning and control. 6

7 PRINCIPLE Various mining hazards are interlinked, they do not happen alone; Detectable symptoms exist prior to disasters happen. 7

8 ROOF COLLAPSE, ROCK BURST Large area of roof sudden collapses, thousands of tons of rock and coal burst out 8 casualties and struct damages.

9 MINE ROOF DEFORMATION Roof monitoring: roof displacement, seismic, not compulsory: Resistance strain gauges, suffer drifts, often off line 9

10 Rock Strain, Roof Displacement Sensors FBG array FBG rock strain sensor array on steel bar FBG roof displacement sensor, d transferred to FBG strain 10

11 Sensors for Water Burst Detection FBG Pressure sensor with built-in temperature sensor; For mineral mine safety application, where major hazards are water flooding, tailing dam, and roof fall. 11

12 Multi-Parameter FBG Sensor Sys. FBG-based T, P, water level, ε, d sensor multiplexing system, WDM & Spatial multiplexing, up to 100 fiber channels, Address >1,000 sensors per system; Mine safety certified (MA); 12 with internet access and TXT message auto-warning.

13 MICRO-SEISMIC SENSOR Cantilever based accelerometer: Acceleration results in mass displacement, then FBG strain variation. 13

14 Micro-Seismic Sensor Interrogation 1. Saw-tooth laser current sweep to locate FBG reflect. Spectrum 2. SCM PID control to lock the DFB LD to -3dB point in the FBG spectrum. 14

15 Micro-Seismic Sensor Interrogation FBG edge to give acceleration signal; 15 PID LD current lock to track FBG slow drift.

16 Micro-Seismic Sensor Character. Sensitivity: 0.1mg; Range: 0-10g. BW: Hz Auto-drift compensation 16

17 COAL MINE FIRE Hegang Spontaneous coal fire causing 19 people died; Henan Province, 17 died in a power cable joint overheat caused fire. 17

18 Mining Power Station Condition Monitoring Internet server On-line high voltage switchgear temperature monitoring FBG Interrogator Fiber connection Optical fiber cable FBG Temperature sensor 18

19 Fire Prediction and Location 6-10 km range T vs L armoured cable for underground mined-out area; Raman DTS along power cable. T Monitor and fire warning location system 19

20 Spontaneous Coal Mine Fire Detection Underground spontaneous coal fire can occur as soon as 14 days after production production; Early detection can be made by monitoring CO CH 4 (@1665nm) and C2H4 (@)1630nm; O2 (@762nm); C2H4/C2H6 vs coal T Ratio of CO/O 2, C 2 H 4 /C 2 H 6 are useful indicators; Require ppm sensitivity and accuracy; 20

21 Multi-Gas Trace Detection System Gas cell laser PD 10 khz Multiple reflection to enhance the detection sensitivity; 2nd harmonic detection and PLIA to reduce noise; ~ 1 ppm sensitivity for CO, sub-ppm for C 2 H 4, C2H6; 21

22 Multiple Gas Trace Detection System LD1 LD2 Switch Switch LD3 Gas cell probe LD PC AD, 1f/2f One gas cell addressed by a bank of laser diodes, which emits at 22 absorption band of the gases to be monitored.

23 Multi-Gas Detection System Modulation frequency signal -0.9 V_2fo/V_fo (au) y = x R 2 = Signal( V ) Sample points 2nd harmonic signal 100ppm 80ppm 30ppm C2H2 Concentration (ppm) C 2 H 2 concentration vs V2f/V1f. V_2fo (v) Sample points 100ppm 80ppm 30ppm 0 Illustration how the harmonic detection system work. 23

24 GASSY MINE DISTRIBUTION,CHINA Over 50% underground coal mines in the world are gassy; 24

25 METHANE EXPLOSION , Shanxi Datong, Explosion, 54 people died; Operation to suppress poisonous gases emitted Jiangxi explosion, 7 people died. 2001, Shanxi, explosion people died

26 Seismic Trigger Methane Gas Burst Seismic Event 17:17 Gas outburst in ~40 minutes From Geo-Physics Vol. 19, p

27 FO Methane Gas Sensor Ambient Gas Sensor Pipeline gas sensor Sensor consists of pairs of fiber collimators as gas cell; Fixing Support and anti-vibration mechanism; Dust and moisture filters 27

28 FO Methane Detection Principle 1665nm DFB LD Laser sweep with internal referencing to achieve field stability. 28

29 FOS Methane Monitor y = x 测量浓度 (%) 标准气体浓度 (%) Unique benefits: Long calibration cycle; Immune to gas cross talk; Robust to humidity and ambient T Intrinsically safe 29

30 Coal Bed Methane Utilization Monitoring - Latest Field Trial concentration(%) data points(once/half hours in two days) fiber gas sensor(ms-gxm-01) Traditional sensor1 Traditional on-line sensor (Huainan Coal Mine methane power generation plant ) 30

31 Coal Mine Methane Utilization Monitoring (Methane extraction power generation plant, Fuxin, Liaoning,

32 Intelligent Mine Safety Platform All fiber optic multi-parameter sensor network, comprising 3 sub-systems; systems; Multiplexed FBG sensor array (d,( P, T, ε,, a, flow, AE) Laser absorption based gas sensor array (Ch4,( CO, C 2 H 4, CO 2, O 2 ) DTS Data fusion system 32

33 FIELD TRIALS: LINGZI COAL MINE, SHANDONG Optical detection Units fiber 光缆 cable PC USB RS232 RS232 RS232 CH4 瓦斯检测 T, P Switch 温度检测 Switch d 应力检测 Switch micro-seismic 矿震检测 Switch 巷道 煤矿井下 Coal production 采煤面 A 温度 A1 瓦斯 A1 应力 A1 温度 A2 瓦斯 A2 应力 A2 掘进面 B 数据库 D/B alarm 报警 Internet 温度 B 1 瓦斯 B 1 应力 B1 温度 B2 瓦斯 B 2 应力 B2 客户端 客户端 Ground Monitor Centre 客户端 Underground 33

34 Field Trial: LINGZI COAL MINE, SHANDONG Temperature Seismic Strain Methane The first trial in

35 FIELD INSTALLATION Strain sensor array CH4 Fire-Proof Cable T Connection 35 Illustration of Fiber Optic Sensor Installation in the Mine.

36 FIELD TRIALS: LINGZI COAL MINE, SHANDONG Water output Optical fiber Pressure sensor Water input Illustration of water pressure measurement using fiber optic pressure sensors. 36

37 FIELD TRIALS: LINGZI COAL MINE, SHANDONG Temperature sensor Fiber optic Methane sensor Fiber Optic temperature sensors and methane sensors installed in underground coal mine. 37

38 FIELD TRIALS: LINGZI COAL MINE, SHANDONG Underground temperature is recorded at approximately 22 degree C, accurate within +/-0.5 degree. 38

39 FIELD TRIALS: LINGZI COAL MINE, SHANDONG blasters Record of methane gas concentration change with time (increase of concentration can be observed after blaster events which agrees with the conventional sensor data). 39

40 Laiwu Iron Ore Mine Roof Monitoring Fiber load cell Displacement sensor 40

41 FIELD TRIALS:Laiwu Iron Ore Mine 系列 4 Fiber seismic sensor mount plate 系列 t Recorded mining blaster signals by two FO seismic sensors located 170 m apart. The time delay is apparent which can be used 41 for seismic source location.

42 FIELD TRIALS: Internet Access The FOS mining safety information system is for on-line remote access via internet. 42

43 Internet access 43

44 Tailings Dam Condition Monitoring Illustration of an iron ore mine tailings dam monitoring system in Beijing, Mineral mine hazards mainly concerned with underground roof and ground tailings dam safety monitoring. Fiber optic water level and displacement Sensor net work are developed. 44

45 Field Trial: Methane Sensor UK Waste Process Power Plant Global secure remote methane monitoring and Data Access On-going field trail min the UK

46 Field Trial: Methane Sensor UK Waste Process Power Plant Global secure remote methane monitoring and Data Access 46

47 Field Trial: Methane Sensor UK Waste Process Power Plant Global secure remote methane monitoring and Data Access Methane Concentration (%) :00:00 04:48:00 09:36:00 14:24:00 19:12:00 00:00:00 Time On-going field trail min the UK

48 On Going Work Comparative Study With PZT Seismic Sensor Network PZT Seismic event location Real PZT Seismic recording And location. Coal Production area To put OFS in the same Location as the PZT and compare sensors 48

49 Challenges and Opportunities OFS can play a key role in enhancing even revolutionizing coal mine and mineral mine safety; Fiber optic FBG sensors, DTS, laser spectroscopic gas sensors, seismic sensors have been successfully demonstrated to become a comprehensive mining safety and hazard management info system The diversified, on-line, multi-location information provides a foundation for more accurate and timely mining hazard early warning and control; 49

50 Challenges and Opportunities OFS intrinsically safe in explosive environment, is irreplaceable for the development of modern intrinsic safe and digital mining. OFS also play key role in environmental system such as coal bed methane utilization... Many opportunities and challenges for OFS application in the mines, e.g. sensitive fiber microphone array for emergency rescue communication; dust monitoring; cable and sensor protection, etc. 50

51 Acknowledgement Thanks to our colleagues at Laser Inst, Shandong Academy of Science and Shandong Micro-Sensor Photonics Ltd; Colleagues in coal and mineral mines for supporting the trials. Grants from National, provincial and the Shandong Academy of Science are acknowledged 51

52 Thank you for your attention! Welcome your collaboration! Together, OFS can save lives and the planet! 52