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Behind the mine accident- the necessity of intellignet monitoring technology

Source:Shenzhen Baianda Communication Co,. Ltd.Time:2017-02-09

     In recent years, China's coal industry is a very prominent problem is mine frequent, to the country and the people's lives and property caused great losses. According to the statistics of the relevant departments, China's annual coal mine accidents due to the number of deaths accounted for 80% of the number of deaths worldwide, millions of tons of mortality close to 6, is the United States as much as 140 times. Although the state has taken stringent regulatory measures, and made a number of documents to emphasize the safety of coal production, but the large and small mine is still occurring.
     Careful analysis of the reasons for the occurrence of these mines, it can be clearly seen in the mine behind, in addition to the coal mine itself, the objective conditions are poor, the safety management system is not perfect and other reasons, the very important point is the mine under the surface monitoring technology Weak and missing.

     1. the structure of coal mine monitoring system

     Coal mine monitoring system is a set of integrated detection technology, communication technology, control technology, computer technology as a whole integrated application system, it and the traditional security system in the video surveillance is very different, not to video image acquisition and processing as the leading The This monitoring includes two levels of content: "monitoring" refers to the coal mine environment and production parameters for automatic detection. "Control" refers to the monitoring of a variety of information for analysis and processing, to develop a corresponding solution to the production site after the feedback to the environment and production process control. In China, the geological conditions of coal mining are not good, coal seam buried deep, poor stability, complex geological structure. Suitable for open-pit mining of coal resources is very small, only 4% of the total coal resources. Therefore, most of the coal mining operations are carried out in the depths of the formation. Which caused the mining prone to water, fire, gas, coal dust, roof and other natural disasters. In this objective environment, the monitoring technology of coal mine monitoring system has become the core problem of safety production. Only by accurately monitoring the real-time value and change of various parameters related to safety production in mine can we take effective method to The normal control of the production process to ensure the safety of underground production.

     2.  The basic working principle of coal mine monitoring system

     The sensor carries out real-time detection of various environmental parameters and important equipment running status of coal mine, and collects and collects the various parameters detected. This monitoring is through the installation of a variety of sensors in the underground collection of environmental parameters, and then these parameters first transmitted to the underground workstation for pretreatment, and then transmitted to the ground through the transmission line, the central station in accordance with the monitoring software pre-defined instructions will The incoming data is analyzed and processed, sent to the underground sub-station, by the sub-station control signals, such as cut off the power, open the emergency channel. At the same time, the central station real-time storage down to send all kinds of data, generate databases and reports. More than the specified value to be prompted, alarm, if necessary, the database part of the data compression package, through the LAN to the upper authorities, the competent departments and then these data to the provincial and municipal safety production supervision departments to achieve more Position supervision. As the coal mine environment is poor, accurate monitoring of various environmental parameters to prevent the occurrence of the most fundamental line of defense.

    3.  The range of coal mine monitoring system

     Coal mine safety monitoring system mainly on the underground environment and production real-time monitoring, the main contents include:
     (1) environmental monitoring: the detection of various harmful toxic gases in the mine and the working environment on the working environment. Such as: methane gas concentration, carbon monoxide, oxygen concentration, wind speed, negative pressure, temperature, rock coal temperature, roof pressure, smoke concentration, real-time digital display.
     (2) production monitoring: monitoring in and out of the main production processes of various production parameters and key equipment operating status parameters, such as: coal warehouse coal level, water level, water supply voltage, power supply current, power and other analog; Hoisting machine, the main fan, the main fan, tape machine, shearer, switch, magnetic starter operating status and parameters, to achieve automatic and manual control.
     Any of these parameters of any of these abnormalities, will affect the safety of the mine production, it must use the computer, all kinds of sensors, signal transmission and processing system for centralized monitoring and control, and in the gas, carbon monoxide and other parameters overrun or underground smoke and Other problems when the alarm, the regional power control.

      4, The underground substation and monitoring sensors

      (1) underground sub-station
      Coal mine monitoring system according to the different equipment manufacturers and slightly different, but its function is basically the following aspects: power-on self-test and the machine initialization, communication testing, sub-station control (such as: to achieve breakpoint, Wind power gas lock, gas pipeline monitoring, environmental monitoring), crash automatically reset.

      The ground center station can initialize and parameterize the underground substation. Such as: sensor adapter channel number, range settings, power points set, alarm, the lower limit settings. Sub-station itself with overrun alarm function. Sub-station receiving center station on the station designated channel output control relay to perform manual operation and off-site power.

     (2) monitoring system with a variety of sensors
      A sensor is a device or device that converts a particular measured information (including physical quantities, chemical quantities, biomass, etc.) into some sort of available signal output. It consists of sensitive components, conversion elements and other auxiliary circuits. The sensing element directly senses the measured information (non-electric) part of the object to be measured, and the switching element can convert the information sensed by the sensitive element directly into an electrical signal and output it through the signal regulating circuit.
     The stability and reliability of the sensor is an important guarantee for the normal operation of the coal mine monitoring system. Currently used for coal mine monitoring and monitoring system sensors are:
     A. Environmental parameters sensor: gas, carbon monoxide, wind speed, negative pressure analog sensor.
     B. Production parameters of the sensor: a variety of temperature parameters, coal warehouse coal, water level, current and voltage, power and other analog sensors.
     C. Equipment status sensor: There are also for the mechanical and electrical equipment open and close, feed status, damper switch status and other switch sensor.

     5.  The problem of coal mine monitoring

     Although the great effort in coal mine safety monitoring, the frequent mine accidents have allowed us to admit that there are still many problems in the monitoring of safety production.

     Monitoring data is missing and inaccurate
     Due to the monitoring of the quality of the sensor or the monitoring point is unscientific, some important downhole environmental parameters have not been accurately measured. The accuracy of the sensor usually represents the reliability of the sensor operation, which is expressed by the following formula:
     Formula: A-sensor accuracy </ P>
     △ A Maximum allowable error within the range of measurement </ P>
     Yfs-full-scale output value </ P>
     This accuracy is actually achieved by repeatedly measuring the degree of dispersion of the results repeatedly over a relatively short period of time. In the domestic sensor test, we found that the measured data deviated from the larger, it is difficult to meet the safety needs of the accuracy. In addition, in the service life, adjustment cycle, zero drift, etc., compared with foreign products, there is a big gap.
     Gas is the most terrible killer mine, many domestic mines have installed a gas concentration monitoring system can be a number of locations downhole for 24 consecutive hours of gas measurement. However, because the underground gas distribution is not uniform, this point of measurement can not achieve a regional spatial gas concentration for all-round measurement. When the monitoring data of the gas concentration at a certain location is not exceeded, and the gas in the adjacent area is likely to have reached the risk level, which is due to the sensor installation location unscientific accidents. </ P>
     In the coal mine monitoring system, the sensor is the first line of defense, it provides the most basic data to prevent accidents. In the choice of sensors, not cheap win, be sure to pay attention to the long-term stability of products and reliability. This is a matter of being directly related to the safety of laborers, and there must be a clear understanding of it.

     Delay of the data

     Various downhole data collected by the sensor need to be uploaded to the underground workstations and the well control center in time to ensure that control measures are taken in the shortest possible time for incident signs. However, due to the instability of the monitoring signal and limited transmission bandwidth and other reasons, resulting in a certain degree of signal transmission delay. Resulting in changes in coal mine gas concentration data can not be monitored in time, resulting in the occurrence of gas explosion. In the future, optical fiber communication will be a large-scale introduction of coal mine monitoring system. The signal from the ground center station to the underground substation is transmitted by optical fiber, which can eliminate the electromagnetic interference of the electrical and mechanical equipment in the mine, reduce the possibility of the external factors such as lightning strike, and improve the stability of the system.

     Communication protocol is not standardized
     National coal mine existing monitoring system equipment by a number of production, each almost all adopt their own dedicated communication protocol, it is difficult to achieve the compatibility of different systems. This has become a coal mine monitoring system transformation, expansion, upgrade a supporting factor. When a system failure and can not be timely repair, it is difficult to use other manufacturers of products to replace, can only make the system sick work, planted a security risk. The root cause of this situation is the lack of uniform standards for the industry.

     Lack of technical staff and low technical level
     In China, coal mining on the scene of the general lack of technical staff, and technical level and work responsibility to be improved. If the field sensor needs to be calibrated at intervals from time to time to ensure the accuracy of the collected data, but in practice often due to the lack of technical staff, the sensor can not be commissioned in accordance with the provisions of the time, making the field test data error, increased the accident risk. </ P>

    6, Measures of coal mine monitoring system
     In view of the country's strong supervision of the safety of coal production, leaders at all levels to prevent the occurrence of mine has been very seriously. Although from the strengthening of the safety management system can have a certain effect, but relying on scientific and technological means to reduce the occurrence of mine should still be the main measure. </ P>
     For the domestic coal mine production safety monitoring system, to improve its system function to better play its role, the following measures are feasible:
     1. Strict quality sensor, to insist on the installation of various types of sensors in the underground high-density regular inspection, calibration and calibration, found that the problem immediately replaced. For poor quality, unstable work of the sensor products to resolutely clear. National authorities should organize the development of a new generation of high reliability sensors. As the new components continue to appear, the sensor production process and manufacturing level also need to improve. In addition to improving the measurement accuracy, response speed, high reliability requirements, the degree of intelligence and integration also need to improve. </ P>
     2. And gradually to the point-to-point cable transmission to bus system to ensure that the face of a uniform distribution of monitoring points, the collection of accurate and reliable signal, and timely upload. Signal transmission media as far as possible the use of fiber optic cable to overcome the underground mechanical and electrical equipment work when the electromagnetic interference. </ P>
     3. The existing coal mine monitoring system to integrate the mainstream products, standardize the communication protocol equipment, and pay close attention to the development of scientific and rational policies and regulations and industry safety standards. In the application of software, should be developed according to the measured environment location parameters for effective risk judgments, analysis, prediction and decision-making solutions.
     4. In the monitoring system running process, the system should have intelligent judgment and self-test function, the equipment can be used in the failure of the analysis. In particular, the sensor sent to the monitoring signal should be able to achieve according to the set value of the analysis and analysis, analysis to determine the signal is true reliability, a timely warning.
     5. Strengthen the construction of video surveillance system, the underground video images collected and uploaded to the ground center station. Duty officers should observe the working status of underground personnel at any time. At the same time, monitor the image to be stored for more than two weeks to ensure that in the event of an accident can be judged according to the image analysis of the cause of the accident, the development of appropriate rescue measures.

 Author: LI Hongbo

     Resource: China Security Network