Coal mine safety has been one
of major social and economic issues that need to be addressed
urgently in China. Recent year, hundreds of death and
injury have been caused by coal mine accidents alone.
To prevent coal mine accidents, protect miners and save
their life, it is very important to detect or measure
all possible parameters that may yield the vital cures
to warn the hazard conditions and prevent the miners from
the mine accident.
For example, by installing temperature
sensors, mine fire can be detected and miners can be
withdraw before it is become hazard; by using strain
sensors at the mine roof., any structure change or movement
can be monitored; by deploying methane sensors, the
concentration of methane level can be detected and the
warning can be issued if the methane level is above
the alert level in the working area.
Although the conventional sensor technologies
can provide a certain level of operating information
in a mine, the drawbacks like single point measurement,
difficulty to achieve remote, on-line measurement, lack
a integrated monitor platform to reflect the full picture
of the operational conditions etc, the monitoring capability
of these traditional sensors will be severely hampered
by their limitation. By take a full advantages and potential
of the fiber optic sensors, a multi-parameter comprehensive
coal mine safety monitoring system has been developed
and successfully deployed in a number of coal mines.
By deploying this fiber optic
sensor based comprehensive real time safety monitoring
system, it is possible to combine the information collected
from multiple sensors and intelligently interpret them
so that the early warning information can be extracted
and the pre-alarm for possible disaster such as hazard
gas outburst, water burst, rock and coal burst, and
mine fire can be issued.
(1) Monitoring of the freezing earth
temperature profile in the monitoring holes at the mine
construction phase using a distributed fiber optic temperature
sensor.
(2) Monitoring of the concrete cure process
and residual stress, displacement, crack etc of the concrete
wall in the mine well. The cure process can be monitored
using multipoint fiber Bragg grating (FBG) temperature
and strain sensors.
(3) Monitoring of ambient temperature
in the working coal seam, excavating track, inclined shaft
etc.
(4) Monitoring of ambient methane gas
concentration using fiber optic methane sensors that is
based on the tunable laser diode absorption spectroscopy.
(5) Monitoring of mine roof pressure
using FBG-based strain sensors.
(6) Monitoring underground water pressure
using FBG-based water pressure sensors.
(7) Monitoring of seismic events using
FBG-based accelerometer sensor array.
(8) Mine fire warning system based
on fiber optic gas sensors for monitoring the concentration
level of CO, CH4, CO2, O2 etc.
(9) Using distributed and multi-point temperature sensors
and fiber optic vibration sensors to monitor the operational
conditions of key mine equipments such as coal conveyor
belts, electrical motors and electrical power supplying
system.
The first all fiber optic senor-based
intelligent coal mine safety multi-parameter monitoring
system has been installed in Linzi Coal Mine, Shandong,
China. Four fiber optic methane sensors, 2 mining pressure
sensors, 2 seismic sensors, 2 water pressure sensors and
10 temperature sensors have been installed at a coal production
front. The distances between the sensors and the monitor
centre were about 5 km. The data were remotely collected
from each sensors and transmitted to the monitor center.
These data can be constantly monitored and recorded via
an internet network. Such information database can also
be accessed through the internet.
