Distributed Fiber Optic Temperature Measurement and Fire Extinguishing Control System for Mining

Based on Standards

2021 Edition of "Coal Mine Fire Prevention and Extinguishing Regulations"

Article 35: When a shaft equipped with a belt conveyor also serves as an intake shaft, the shaft must be equipped with automatic alarm and automatic fire extinguishing devices, and fire-fighting pipelines must be laid.

Article 55: Belt conveyors must be equipped with protection devices against slipping, deviation, coal piling, tearing, etc., and should also be equipped with temperature and smoke monitoring devices and automatic sprinkler systems. It is advisable to set up an automatic fire extinguishing system with real-time monitoring functions.

System Introduction

The KJ1959 Distributed Fiber Optic Temperature Measurement and Fire Extinguishing Control System for Mining (hereinafter referred to as the "System") is an automatic alarm and fire extinguishing system developed by our company specifically for some key fire-prone areas underground in coal mines, combining fiber optic temperature measurement and sensor real-time fire monitoring.

When a fire occurs, combustion produces a large amount of heat as well as smoke, flames, carbon monoxide, and various mixed gases. The system mainly detects these environmental characteristics of fire to intelligently determine whether a fire has occurred and automatically performs voice, light, and sound alarms and fire extinguishing operations.

System Applications

(1) Real-time temperature monitoring and positioning of key parts such as belt conveyor channel steel, bearings, rollers, head and tail; fire prevention and extinguishing in electromechanical chambers and temporary power distribution points; online monitoring of environmental temperature in underground goaf areas and fire early warning;

(2) By monitoring and analyzing real-time temperature data, determine equipment operating status, eliminate faults and accidents at an early stage, and prevent problems before they occur;

(3) The software features temperature anomaly alarms, temperature anomaly point positioning, real-time temperature curve display, temperature historical data query, electric ball valve status, smoke sensor status, carbon monoxide values, and other real-time monitoring functions;

(4) The system can set alarm functions: including fixed temperature alarm (set maximum/minimum temperature values), differential temperature alarm (large difference between real-time temperature and average temperature to identify local hotspots), rapid temperature rise alarm, fiber optic damage alarm, device abnormality alarms, etc.

Principle Explanation

The system's core device, the KJ1959-Z mining explosion-proof and intrinsically safe distributed fiber optic temperature measurement host, contains a fiber optic temperature measurement module, automatic fire extinguishing control module, and communication transmission module. The fiber optic temperature measurement module is a real-time online continuous data uploading measurement technology using fiber optic as the carrier for temperature sensing and signal transmission, based on the backward Raman scattering effect. Laser pulses enter one end of the fiber optic cable, and during forward propagation, molecular interactions cause various types of scattering. Using Optical Time Domain Reflectometry (OTDR) principles, distributed measurement of the temperature field along the fiber optic cable is achieved, enabling early prediction of goaf areas and fire source positioning as well as automatic fire extinguishing functions. It can provide temperature distribution and alarm positioning within 0.3 meters accuracy for belts inside shafts. The temperature measurement cable is laid along both sides of the conveyor belt starting from the temperature measurement host, enabling immediate temperature monitoring of the belt.

The automatic fire extinguishing control module can monitor sensor values of flames, carbon monoxide, smoke, etc. in real time. Once abnormal values are detected, it automatically determines whether a fire has occurred. If a fire occurs, it immediately controls the corresponding electric ball valve to spray water for extinguishing or controls the dry powder fire extinguishing device to extinguish the fire. This achieves 3D full-area monitoring and automatic fire extinguishing operation for belt fire hazards.

The communication transmission module mainly communicates data with the surface monitoring station, enabling data upload and download.

System Composition

The system mainly consists of the KJ1959-Z mining explosion-proof and intrinsically safe distributed fiber optic temperature measurement host (hereinafter referred to as the "host"), mining intrinsically safe voice and light alarm, mining carbon monoxide sensor, smoke sensor, mining intrinsically safe flame sensor, mining intrinsically safe electric ball valve, fire extinguishing water curtain, mining explosion-proof and intrinsically safe DC stabilized power supply, dry powder fire extinguishing device, powder spraying pipeline, monitoring system, Ethernet switch, etc.

Associated Components Introduction

Mining Explosion-proof and Intrinsically Safe Distributed Fiber Optic Temperature Measurement Host

1. Power Supply Voltage: Underground AC127/380/660V selectable; Surface AC220V;
2. Measurement Channels: 8 channels;
3. Temperature Measurement Range: 0～90℃ (depending on the temperature measurement cable);
4. Single Channel Measurement Distance: 4km (customizable extension available);
5. Communication Interfaces: RJ45 electrical port, SC optical port, RS485, relay output;
6. Temperature Measurement Accuracy: ±1℃;
7. Positioning Accuracy: 0.5m;
8. Measurement Time ≤2s per channel;
9. Spatial Resolution: ≤1m;
10. The host is equipped with a color LCD screen that can display zone alarms, over-temperature alarms, fiber break fault alarms, temperature curves, historical data, etc.;
11. The host has alarm output points internally and can be directly configured with mining intrinsically safe voice and light alarms;
12. Explosion-proof Type: Mining explosion-proof and intrinsically safe, explosion-proof mark: Ex db [ib Mb]I Mb.

Mining Intrinsically Safe Voice and Light Alarm

1. Rated Operating Voltage: DC18V;

2. Operating Current: ≤600mA;

3. Communication Signal: RS485;

4. Voice File Storage: 30 files;

5. Main Functions

a. Has the function to play stored voice files;

b. Has audio-visual alarm function, the alarm light signal is clearly visible at 20m distance in a dark environment.

6. Explosion-proof type: intrinsic safety type for mining, explosion-proof mark: Ex ib I Mb.

Mining Carbon Monoxide Sensor

1. Operating voltage: 18VDC;

2. Operating current: ≤200mA;

3. RS485 output signal

a. Number of channels: 1 channel;

b. Baud rate: 2400bps;

4. Measurement range and resolution

a. Measurement range: (0～1000)×10-6 CO;

b. Resolution: 1×10-6 CO.

5. Explosion-proof type: intrinsic safety type for mining, explosion-proof mark: Ex ib I Mb.

Mining Intrinsic Safety Smoke Sensor

1. Rated operating voltage: DC18V;

2. Operating voltage range: DC9V～DC24V;

3. Maximum operating current: ≤200mA;

4. Sensitivity and response time

When smoke concentration reaches 5% obs/m, the sensor should activate, and the response time should not exceed 20s.

5. Operating performance

When smoke concentration ≥5% obs/m, the red LED light stays on, buzzer alarms, relay activates, RS485 outputs alarm signal;

When smoke concentration <5% obs/m, the red LED light turns off, buzzer stops, relay resets, RS485 outputs normal signal.

6. Sensor output signals

a. RS485 signal;

b. Passive node signal;

7. Explosion-proof type: intrinsic safety type for mining, explosion-proof mark: Ex ib I Mb.

Mining Intrinsic Safety Flame Sensor

1. Operating voltage: DC12-16V;
2. Operating current: 16-40mA;
3. Output signal: No fire alarm signal: high impedance state, high level ≥13V; fire alarm signal: low level ≤3V.

Mining Intrinsic Safety Electric Ball Valve

1. Rated operating voltage: DC 12V;
2. Rated operating current: ≤500 mA;
3. Operating pressure range: 0.2～7MPa;
4. Nominal diameter: 20mm;
5. Delay time: 0～9999s, set by remote control;
6. Signal transmission: 2 channels of high/low level signals; 2 channels of RS485 signals;
7. Display method: LCD display, clearly shows current ball valve working status, sensor data, etc.;
8. With remote calibration function, all parameters can be remotely modified via remote control;
9. Explosion-proof type: intrinsic safety type for mining, explosion-proof mark: Ex ib I Mb.

Mining Flameproof and Intrinsic Safety DC Regulated Power Supply

1) Rated operating voltage: AC127V/220V/380V/660V;

2) Input apparent power: ≤150VA;

3) Power supply fluctuation range: 75%～110%;

4) Output voltage: 1 channel 12V; 1 channel 18V.

5) Main functions

a. When AC power is off, the backup battery immediately automatically starts working.

b. The power supply has overcurrent, overvoltage, and short circuit protection functions. When a fault occurs, the power supply automatically protects itself and automatically resumes normal operation after the fault is cleared.

c. The power supply has AC/DC working status indication function.

6) Explosion-proof type: mining flameproof and intrinsic safety type, explosion-proof mark: Ex db [ib Mb]I Mb.

System Features

(1) Three-dimensional temperature measurement, no blind spots, temperature measurement along the line as the temperature measurement optical cable is laid.

(2) Accurate temperature measurement, accuracy up to ±0.1℃.

(3) Temperature alarm mode can be flexibly set.

(4) The working status of the electric ball valve can be viewed in real time.

(5) The number of electric ball valves to open can be set in the software: fully open/single open/adjacent open.

(6) The system configuration is flexible and can be combined according to different occasions.

(8) Temperature information is sensed by optical fiber, intrinsically safe, electromagnetic interference resistant, and highly stable;

(9) Temperature information is transmitted through optical signals, unaffected by electromagnetic interference;

(10) It has high sensitivity and resolution, a wide measurement frequency band, fast response speed, and a large dynamic measurement range;

(11) Long measurement distance, small size, intrinsically non-electrified, simple wiring, unaffected by electromagnetic interference, and good radiation resistance;

Main Technical Parameters

(1) Analog input transmission processing error not greater than 1%;

(2) Maximum system inspection cycle not greater than 30s;

(3) Remote control response time not greater than 30s;

(4) Response time for calling up 85% of the full screen not greater than 2s, other screens not greater than 5s;

(5) Time from main host failure to manual switching to backup host normal operation not greater than 5min;

(6) System transmission error rate not greater than 10 ^-8 ；

(7) Real-time monitoring values of important monitoring points' analog quantities can be saved for more than 7 days; records of analog quantity statistics, switch status and change times, equipment failure/recovery times and statuses can be saved for more than 1 year. When the system fails, the lost time of the above information is not greater than 5 minutes.