NASKOVICH VITALIY ALEKSEEVICH
Master of the faculty: computer information technology and automations
profession: automated managerial system
subject master work: development of the computer system to metanew to dangers and his monitoring in coal mine
project manager: prof. Krasik Y. L.
alekseich2004@mail.ru

7th International Mine Ventilation Congress June 17-22, 2001, Cracow, Poland

        METHANE HAZARD AND ITS MONITORING

        In the paper the results of research on methane hazard and its monitoring for mines exploiting coal seams with blow methane emission and also inclined to sudden outbursts of coal and gas are given. A method of the analysis of the «Operator-Machine-Environment» system is considered to formulate definition of different sorts of hazard and multi-factor systems for explosion-hazard states monitoring with the help of the analysis of risk factors is described. The theoretical version for an estimation of probability of an average number of air-methane mixtures explosions is given at presence of statistical data, and also methods for an evaluation of the hazard monitoring system as a whole and estimation of safe time of its stay in an abnormal state.
        In the majority of mining sites of Ukraine the coal seams with high methane content, inclined to sudden outbursts of coal and gas as well as blow emission of methane are mined Currently used methods of the outburst hazard prediction and control of gas emission speed, and also the seismoacoustic method of similar assignment becomes all less reliable in connection with transition of mining operations to more deep horizons (1000 m and more). The process of shaft drilling is unsafe because of appearance of sudden outbursts and others gas dynamic phenomena.
        The seismoacoustic method in main meets the requirements of mining, however, the area of its application is limited to a level seismoacoustic properties of a coal seam. Besides, this method does not allow to differentiate the prediction of dangerous zones with regard to dynamic appearances along the whole length of the coal face, and also it does not takes into account how the outburst hazard is influenced by such factors as rock pressure, gas content and physics-mechanical characteristics of a coal seam when it is destroyed during mining operations.
        Research carried out by AWTOGORMASZ, MAKNH and IGD in the years 1980-1985 confirmed expediency of creation of the system for automatic outbursts hazard prediction of coal seams based on a control and analysis of the multifactor information.

        MULTIFACTOR SYSTEMS FOR METHANE EXPLOSION DANGER MONITORING IN COAL MINES

        The operation conditions of coal mines in Ukraine differ from the majority of mining companies in other countries of the world mainly by high level and diversity of sorts of hazards.
        During the last eight years (1991-2000) there were more than 40 explosions and serious fires in Ukrainian underground mines. As a result of these accidents more than 500 men have died. The majority of explosions were initiated by explosions of methane in longwalls and headings or as a result of gas outbursts. The explosions with the most serious consequences were frequently caused by coal-dust explosions initiated by explosions of methane.
        At the beginning of thud millenium the level of electronic and information technologies in the world has reached considerable heights which has created new possibilities in the field of safety of technological operations in coal mining industry.
        The system analysis of dangerous situations which can led to crashes (including those with tragical consequences) convinces that the monitoring system of safety parameters is a multifactor one.
        The modern hardware of information systems with the mandatory prediction and estimation of danger and degree of risk of carried out technological task will allow to essentially reduce a number of tragedies in Ukrainian coal mines.
        The system is open and can be supplemented by other subsystems qualitatively fulfilling the prediction and estimation of safety of technological processes.
        The most dangerous risk factors in underground workings are the explosions of gas and dust.
        The explosion itself is usually preceded by confluence of a number of circumstances arising at presence of objectively existing sorts of danger, such as sudden outbursts, rock bumps, methane accumulation in dangerous concentration, poor ventilation, sources of fire hazard, abnormal rise of ambient temperature, absence of minewide systems for monitoring states of isolation of high-voltage cable networks, underground substations and protection circuits, sources of potentially possible sparking etc.
        The simple listing and brief analysis of different sorts of danger which accompany underground mining operations distinctly shows the multifactor character of all processes which precede ignition (explosion) of technological environment of a coal mine.
        The events that precede development of catastrophe, as a rule, carry a random character. They are conditioned by origin and development of several sorts of threat and can be detected with the help of means of continuous control, multifactor analysis and prediction of crash development.
        The manufacturers-developers, as a rule, are occupied in creation of means to control of different sorts of danger. In solving this problem no system approach and no multifactor estimation of safety of mining operations management is used
        The idea of this work consists in multifactor control, analysis and prediction of different sorts of hazard originating at realization of mining operations, with maximum use of technical means and operating on the basis of the created algorithms and special software, giving on the terminal device output information about development of danger situation in a form of three conditions: «normal slate», «danger», «stop operations
        The information can be saved in a special memory during time defined by a requirement specification at the system.
        The purpose of this work is to develop and introduce the system of a multifactor monitoring, prediction and instrumental estimation of safety of mining operations in underground coal mines both at longwalls and development workings.
        The work can be fulfilled with maximum use of currently produced and being developed devices for monitoring of ventilation parameters, outburst hazard and other factors which unfavorable combination carries on to origin of an explosion-threat situation.
        The «System ... » consists of subsystems which process and monitor information about:
        • outburst and bumps hazard;
        • state of mine ventilation and temperature conditions;
        • state of cable networks and substations, commutative apparatus and protection circuits;
        • concentration of CH4, CO, volume of intake air,
        • fire hazard and equipment for dust suppression;
        • sources of ignition and potentially possible sparking.
        At a general-system level the tasks of the multifactor analysis of situational conditions should be solved with regard of actual risk factors and the most dangerous coincidences of these factors should be determined for acceptance of concrete solutions.
        The application software of processing and output of the information being a system kernel, includes special processing algorithm for an evaluation of danger degree for each of subsystems or system as a whole. This involves that special programs for information processing should be made, basing on logical relations and using probability and regression methods of information analysis. Wide usage of a state-space method and features of expert systems is also necessary in the software.
        The «System...» is open and can be easily supplemented by additional subsystems, e.g. those to monitor rock pressure in dangerous zones, and other monitoring functions that can positively influence the safety of mining operations.
        Creation of such system will with great profit be paid back if even one of possible mine catastrophes is avoided.
        It is obvious that only system approach to evaluation of development of abnormal situation in combination with a multi-factor monitoring and prediction of a state of mining operations safety, instrument estimation and computer processing of information can rationally change the actual state in this area of underground mining.
        The system of safety state evaluation, presently existing on mines, has practically no generalized information for a complex estimation of safety on separate sites of a mine. Each particular staff of a mine is responsible for its own part of safety and has an access to the "own" information on threats pursuing the miner. Besides, existing on mines monitoring of sorts of threats is periodic, and only parameters of a methane emission are inspected continuously in rather limited number. This information reaches, with considerable delay, people responsible for safety. That procedure does not allow to effectively track the origin of a dangerous situation, to forecast its development and to make a decision on localization and removal of threat in time.
        Taking above into account, seems to be rational to create and implement a complex system of a multifactor monitoring and instrumental evaluation of state of mine technological processes safety. The system should provide early detection and continuous monitoring of potential sorts of threat, mapping dangerous zones on displays together with warning information and short instruction for miners being presently within dangerous zones, and also recording and mapping of parameters monitored by subsystems.
        The further growth of longwall load and rise of productivity of miners work is impossible without advance in the field of mine safety. That is why the highest priorities should be given to those problems.

        SUMMARY

        This paper is devoted to an actual problem of methane danger warning with the help of monitoring systems.
        The theoretical aspects of origin of explosions are considered. In view of the obtained results it the following recommendations can be formulated:
        • mine environment should be considered as the potential source of explosion, for which research is necessary to define risk factors, using for the analysis the three-part system «Operator - Machine - Environments.
        • as technical means it is necessary to use multifactor systems for monitoring and prediction of hazards with the purpose of anticipation of development of a crash;
        • with the help of theoretical methods is shown that the losses can be diminished or even eliminated with the help of means of a continuous monitoring of methane conditions and potential sources of sparking;
        • the mean value of a restoring time of the monitoring system should be obligatorily less than safe time of the system stay in a state of failure.