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 16.10.2009 HAZARD MONITORING IN MINES USING FIBER OPTIC SENSORS
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Fiber Optic Sensor in Mine Hazard Monitoring · 2 OUTLINE nBackground - Mine Hazards nFOS based Intelligent Mine Safety Monitoring Systems nRoof condition and water burst monitoring
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T. Liu, C. Wang, Y. Wei, Y. Zhao, Y. ShangLaser Inst. Shandong Academy of Science, China
D. Huo, Z Wang
Yanong NingIntelligent Sensor Systems Ltd. UK
Presentation: S&A IOP and OFS-20, Edinburgh 16.10.2009
HAZARD MONITORING IN MINES USING FIBER OPTIC
SENSORS
22
OUTLINE
nnBackground Background -- Mine HazardsMine HazardsnnFOS based Intelligent Mine Safety Monitoring SystemsFOS based Intelligent Mine Safety Monitoring SystemsnnRoof condition and water burst monitoringRoof condition and water burst monitoringnnEarly fire detectionEarly fire detectionnnPower safety monitoringPower safety monitoringnnSpontaneous fire early warningSpontaneous fire early warning
nnMethane gas monitoringMethane gas monitoringnnField trials: coal mines, tailings dam landslide Field trials: coal mines, tailings dam landslide nnSummarySummary
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CHINESE COAL MINE INDUSTRYnnCoal provides majority of the energy (>70%); Coal provides majority of the energy (>70%); nnAnnual Production: ~3 billion tons,Annual Production: ~3 billion tons,nn ~ 1/3 of world coal production;~ 1/3 of world coal production;
nnNumber of coal mines: ~15,000Number of coal mines: ~15,000nn -- State and local government own ~3,000, State and local government own ~3,000,
the rests are small mines;the rests are small mines;nnUsed to be >70,000 mines Used to be >70,000 mines nnKey Issue: Key Issue: SAFETYSAFETY
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COAL MINE SAFETYn2001-2005: nNumber of coal mine accidents:18,516nNumber of death: 31,064 (AVE: 17 per day !)nIn recent years, both the government and the mine operators invested heavily on safety technologies, the fatality rate dropped, but total number still very high.
nFATALITIES DUE TO EXPLOSION: nState owned mine groups have world class safety standard;n However, in small mines casualty rate over 100 times higher.
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MAJOR COAL MINE HAZARDS
2006 Jan-Oct: FatalitiesGASOUTBURST
ROOF
WATER
TRANSPORT
FIRE
BLASTERS
346
415
75
987
1615
Roof collapse, rock & coal outburst
Methane explosion
Flooding
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n To develop a comprehensive mine disaster management system based on fiber optic sensor network, nCapable of mining hazard early warning and control.
MOTIVATION
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n Various mining hazards are inter-linked, they do not happen alone;n Detectable symptoms exist prior to disasters happen.
PRINCIPLE
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ROOF COLLAPSE, ROCK BURST
n Large area of roof sudden collapses,n thousands of tons of rock and coal burst outn casualties and struct damages.
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MINE ROOF DEFORMATION
nRoof monitoring: roof displacement, seismic, not compulsory:n Resistance strain gauges, suffer drifts, often off line…
1010
Rock Strain, Roof Displacement Sensors
n FBG roof displacementsensor,n d transferred to FBG strain.
n FBG rock strain sensor array on steel bar
FBG array
1111
Sensors for Water Burst Detection
n FBG Pressure sensor with built-in temperature sensor;n For mineral mine safety application, where major hazards are water flooding, tailing dam, and roof fall.
1212
Multi-Parameter FBG Sensor Sys.
n FBG-based T, P, water level, ε, d sensor multiplexing n system, nWDM & Spatial multiplexing, up to 100 fiber channels,n Address >1,000 sensors per system;n Mine safety certified (MA); n with internet access and TXT message auto-warning.
1313
nCantilever based accelerometer: nAcceleration results in mass displacement,
then FBG strain variation.
MICRO-SEISMIC SENSOR
1414
Micro-Seismic Sensor Interrogation1. Saw-tooth laser current sweep to locate FBG reflect. Spectrum
2. SCM PID control to lock the DFB LD to -3dB point in the FBGspectrum.
1515
Micro-Seismic Sensor Interrogation
nFBG edge to give acceleration signal;nPID LD current lock to track FBG slow drift.
COAL MINE FIREn2008.09 Hegang Spontaneous coal fire causing 19 people died;
n2007.02 Henan Province, 17 died in a power cable joint overheat caused fire.
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FBG Interrogator
Optical fiber cable
On-line high voltage switchgear temperature monitoring
Internet server
Fiber connection
Mining Power Station Condition Monitoring
FBG Temperature sensor
1919
narmoured cable for underground mined-out area;nalong power cable.
Fire Prediction and Locationnn 66--10 km range10 km range
nRaman DTS nT Monitor and fire warning nlocation system
T vs L
2020
Spontaneous Coal Mine Fire Detection
n Underground spontaneous coal fire can occur as soon as 14 days after production production;n Early detection can be made by monitoring CO (@1567nm), CH4 (@1665nm) and C2H4
(@)1630nm; O2 (@762nm);
nRatio of CO/O2, C2H4/C2H6 are useful indicators;n Require ppm sensitivity
and accuracy;
C2H4/C2H6 vs coal T
2121
Multi-Gas Trace Detection System
n Multiple reflection to enhance the detection sensitivity;n 2nd harmonic detection and PLIA to reduce noise;n ~ 1 ppm sensitivity for CO, sub-ppm for C2H4, C2H6;
laser
Gas cell
10 kHz
PD
2222
Multiple Gas Trace Detection System
LD1
LD2
LD3
SwitchSwitch
Gas cell probe
AD, 1f/2fPC
LD…
nOne gas cell addressed by a bank of laser diodes, which emits atn absorption band of the gases to be monitored.
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Multi-Gas Detection System
y = 0.0033x - 0.0043
R2 = 0.9988
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0 20 40 60 80 100 120
C2H2 Concentration (ppm)
V_2f
o/V_
fo
(au)
2nd harmonic signal
-1.8
-1.6
-1.4
-1.2
-1
-0.8
-0.6
0 50 100 150 200 250 300
Sample points
V_2fo (v)
100ppm
80ppm
30ppm
0
Modulation frequency signal
-1.5
-1.4
-1.3
-1.2
-1.1
-1
-0.9
0 50 100 150 200 250 300
Sample points
Signal(
V) 100ppm
80ppm
30ppm
0
n C2H2 concentration vs V2f/V1f.
Illustration how the harmonic detection system work.
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GASSY MINE DISTRIBUTION,CHINA
nnOver 50% underground coal mines in the world are gassy;Over 50% underground coal mines in the world are gassy;
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n2001.11, Shanxi Datong, nExplosion, 54 people died;n Operation to suppress poisonous gases emitted.
METHANE EXPLOSION
n2006.11 Jiangxi explosion,7 people died.
n2001, Shanxi, explosion99 people died
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From Geo-Physics Vol. 19, p 856
Seismic Event 17:17
Gas outburst in ~40 minutes
Seismic Trigger Methane Gas Burst
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FO Methane Gas Sensor
n Ambient Gas Sensor
n Pipeline gas sensor
nSensor consists of pairs of fiber collimators as gas cell;nFixing Support and anti-vibration mechanism;nDust and moisture filters
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FO Methane Detection Principle
1665nm DFB LD
nLaser sweep with internal referencing to achieve field stability.
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y = 1.0025x + 0.0526
0
2
4
6
8
10
12
0 2 4 6 8 10 12
标准气体浓度(%)
测量浓度(%)
FOS Methane Monitor
n Unique benefits: n Long calibration cycle;n Immune to gas cross talk;n Robust to humidity and ambient Tn Intrinsically safe
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Coal Bed Methane UtilizationMonitoring - Latest Field Trial
n(Huainan Coal Mine methane power generation plant 2009.09)
fiber gas sensor(MS-GXM-01) Traditional sensor1 Traditional on-line sensor
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Coal Mine Methane Utilization Monitoring
(Methane extraction power generation plant, Fuxin, Liaoning, 07. 2008
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Intelligent Mine Safety Platform
nnAll fiber optic multiAll fiber optic multi--parameter sensor parameter sensor network, comprising 3 subnetwork, comprising 3 sub--systems;systems;nn Multiplexed FBGMultiplexed FBG sensor array (sensor array (d, P, d, P, T, T, εε, a, flow, AE, a, flow, AE))nn Laser absorptionLaser absorption based gas sensor based gas sensor array (array (Ch4, CO, CCh4, CO, C22HH44, CO, CO22, O, O22))nn DTSDTSnnData fusion systemData fusion system
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瓦斯检测
温度检测
应力检测
矿震检测
USB
RS232
RS232
RS232
PC
Switch
Switch
Switch
Switch
光缆
巷道
采煤面A
掘进面B
温度A1
温度A2
温度B1
温度B2
瓦斯A1
瓦斯A2
瓦斯B1
瓦斯B2
应力A1
应力A2
应力B1
应力B2
数据库
Internet
客户端
煤矿井下
报警
客户端 客户端
CH4
Optical detection Units
T, P
d
micro-seismic
fiber cable
Ground Monitor Centre Underground
FIELD TRIALS: LINGZI COAL MINE, SHANDONG
Coal production
D/B alarm
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Field Trial: LINGZI COAL MINE, SHANDONG
Temperature
Seismic
Strain
Methane
The first trial in 2007
3535
FIELD INSTALLATION
Fire-Proof CableConnection
Strain sensor array
Illustration of Fiber Optic Sensor Installation in the Mine.
T
CH4
3636
FIELD TRIALS: LINGZI COAL MINE, SHANDONG
nIllustration of water pressure measurement using fiber optic pressure sensors.
Optical fiber Pressure sensor
Water input
Wateroutput
3737
FIELD TRIALS: LINGZI COAL MINE, SHANDONG
nFiber Optic temperature sensors and methane sensors installed in underground coal mine.
Temperature sensorFiber opticMethane sensor
3838
FIELD TRIALS: LINGZI COAL MINE, SHANDONG
nUnderground temperature is recorded at approximately 22 degree C, accurate within +/-0.5 degree.
3939
FIELD TRIALS: LINGZI COAL MINE, SHANDONG
nRecord of methane gas concentration change with time (increase of concentration can be observed after blaster events which agrees with the conventional sensor data).
blasters
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Laiwu Iron Ore Mine Roof Monitoring
Displacement sensor
Fiber load cell
4141
nRecorded mining blaster signals by two FO seismic sensors located 170 m apart. The time delay is apparent which can be used for seismic source location.
25000
27000
29000
31000
33000
35000
37000
39000
0 500 1000 1500 2000
系列4
25000
27000
29000
31000
33000
35000
37000
39000
0 500 1000 1500 2000
系列3
FIELD TRIALS:Laiwu Iron Ore Mine
Fiber seismic sensormount plate
∆t
4242
FIELD TRIALS: Internet Access
n The FOS mining safety information system isfor on-line remote access via internet.
4343Internet access
4444
Tailings Dam Condition Monitoring
nMineral mine hazards mainly concerned nwith underground roof and ground tailingsndam safety monitoring.nFiber optic water level and displacement nSensor net work are developed.
Illustration of an ironore mine tailings dam monitoring system in Beijing, 06.2008.
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Field Trial: Methane Sensor UK Waste Process Power PlantnGlobal secure remote methane monitoring and Data Access
nOn-going field trail min the UK 09.2009.
4646
Field Trial: Methane Sensor UK Waste Process Power PlantnGlobal secure remote methane monitoring and Data Access