29th International Conference of Safety in Mines Research Institutes, Аvtor: Yu. F. Bulgakov "The basic pricipeles and aspects of development of the mine automatic fire protection systems."

A new principle of development of the automatic fire protection systems based on the conception of the underground fire as a controlled system with certain parameters (temperature, heating rating, velocity of propagation along the mine working) that predetermine selection of methods and combination of fire-fighting means guaranteeing the maximum possible fire-extinguishing efficiency for. each concrete fire is expounded. Technical characteristics of the newest systems intended for fire protection of the mine workings and the mining equipment are substantiated. Analysis of designs of the existing home and foreign fire-fighting means is fulfilled. It is shown that in spite of the rather wide stores of the modern mine fire-fighting systems their structure can be brought to the common not complicated block diagram that includes subsystem of monitoring the environmental parameters, subsystem of fighting the fires, lock and starting valves, distributing pipeline with sprayers as well auxilliary monitoring and measuring devices. The principal parameter that is controlled by the mine fire-fighting systems is the temperature. It is checked by means of the mine heat fire detectors that are intended to warn about elevation of the air temperature sin the mine working being protected. Besides the heat fire detectors the smoke detectors of various design can belong to the complete set of the mine automatic systems.

INTRODUCTION

The underground fires remain one of the most complicated and hazardous kinds of accidents ac present that devastate entrails of the earth, destroy mine workings and expensive equipment, do enormous moral and material damage to coal enterprises and are frequently accompanied by victims. In the mines of Ukraine 160. ..200 underground fires occur on the average every year, 50. ..70 % of which are the open ones (figure 1). Fighting the developed underground fires is one of the most complicated and actual scientific and technical problems of coal industry. Two ways of solving this problem exist: the first way is-wide use of the scientifically grounded preventive measures that exclude possibility of ignition and following fire development, and the second one is creation of methods and means of fighting the developed fires.

Figure 1. Number of open fires in mines of the Ministry of Fuel and Energy (Mintopenergo) of Ukraine.

Figure 2. Economic damage stipulated by the open fires in mines of the Mintopenergo of Ukraine.

The scientific-research and project and development works in the sphere of prevention and fighting the open fires are directed to development of the high-efficient fire-fighting equipment with use of water, air-mechanical foam, inert gases, fire-extinguishing powders, aerosols as well their combinations as fire-fighting substances. Water remains the most widespread and cheap fire-fighting means on account of its unique physical properties. The automatic plants that are possible to protect effectively the mine workings and technological equipment against the underground fires are of the. greatest interest. The basis of conception of creation of the modern mine automatic fife-fighting systems is the; principle based on idea that the underground fire is a controlled system with certain parameters (temperature, heating rating, velocity of propagation along the mine working) that predetermine selection of methods and combination of fire-fighting means guaranteeing the maximum possible fire-extinguishing efficiency for each concrete fire. In spite of this the automatic system realizes steady monitoring of the environment checking its parameters and comparing them with regulated values for the purpose of producing the control signal to switch on the fire-fighting plants. The principal parameter that is controlled by the mine fire-fighting systems is the temperature. It is checked by means of the mine heat fire detectors that are intended to warn about elevation of the air temperature in the mine working being protected. Besides the heat fire detectors the smoke detectors of various design can belong to the complete set of the mine automatic systems. One of the most significant aspects of creation of the mine automatic fire-fighting systems is scientific substantiation of selection of type and design of the fire detector depending on its purpose and service conditions. One can determine sluggishness of the fire detector for the case of convective heat exchange on the dimensionless parameter Q and criteria Bio (Bi) and Fourier (Fo):

where tw, tf and t0 - temperature of detector operation, temperature of environment by the fire in the place of detector location, and initial temperature before the fire, °C accordingly.


The fire detectors with the operation temperature of 72 °C are used in the designs of the modern mine fire-fighting systems. In spite of the rather wide stores of the modern mine fire-fighting systems their structure can be brought to the common, not complicated block diagram that includes subsystem of monitoring the environmental parameters, subsystem of fighting the fires, lock and starting valves, distributing pipeline with sprayers as well auxiliary monitoring and measuring devices and devices for preparation and technical maintenance of the system. The powder systems that can efficiently fight the fires of the A, В, С classes, as well ignition of the electrical equipment at a voltage up to 1140 V are most universal from the point of view of various classes of the underground fires. The typical block diagram of the mine dry-powder fire-fighting system is presented in figure 3. As a rule, the parts of the system are: automatic fire-fighting plant, АУПП type (or its modifications) with starting units (of mechanical and electrical switching-on), light and audible warning devices, distributing pipe-lines (perforated or with sprayers), fire-alarm station, СЦ-1, СЦ-2. СП-types (or their modifications) with the set of fire, heat or smoke detectors, signaling stabs and switching elements. The dry-powder fire-fighting systems operate as follows. The fire detector that is the nearest one to the ignition source operates by the fire in the zone being protected. The electric signal comes from it to the fire-alarm station that switches on the light and audible alarms and begins realization of logical estimation of the arrived pulse determining its value and nature of origin. In this case the station checks integrity of stabs uniting the detectors with each other, determines availability of short circuit current in their circuit, integrity of the detectors and "de-excitates" the diagnostics results on the control panel. In the case of operation of the second detector the station produces the control electric signal to start the fire-fighting plant. The automatic plants are started by means of the starting devices (units) which design is determined by the purpose of the system. Logical processing the signals that arrive from the fire detectors is realized by the СЦ station. Principle of operation, design, technical parameters, installation rules and other information about the СЦ station are presented in the Specifications.

Volume protected by one automatic fire-fighting plant with charge mass of 80 kg of fire-extinguishing powder, П-2АП type, or of analogous class, m3, not less than 250
Sluggishness of the automatic plant - time from operation of the starting unit to beginning of gas-powder mixture outle from sprayers or perforation openings, sec 10... 12
Operation temperature of sensors, °C 72
Operation temperature interval of the station, СЦ-1 type, and its modifications, °C -10...+50
Operation temperature interval of vessels of the automatic plants, АУПП type, °C -35...+55
Supply voltage of the station and starting units, V 220

Compressed air pressure in cylinders of the plants, MPa 15 Mass of liquid carbon dioxide in cylinders of the plants at a temperature of 20 °C, kg 2.8...3.0
Starting pressure of working gas in vessels of the plants, MPa 0.7...0.9
Mass of the automatic plant charged, kg 145
Total service life, years, not less than 6
Number of stabs being controlled, pieces
СЦ-1 10
СЦ-2 20 The system can "recognize" at the early stage and fight the underground fires of the А, В, С classes and ignitions of the electrical equipment being at the voltage up to 1140 V. Procedure of calculation of the principal parameters of the mine automatic plants forming a part of the fire-fighting systems is worked out. Besides that, procedure of determination of fire-fighting efficiency of the automatic fire-fighting systems is developed. It includes determination of capacity of the fire-fighting modules, mass of fire-fighting charge, working pressure values in the working vessels, as well calculation of design parameters of the plants and characteristics of the distributing pipe-lines. Natural fire tests of the systems, САП-1 type, were carried out that confirmed their reliability and high fire-fighting efficiency.

The principle of development of the mine automatic fire-fighting systems based on the conception of the underground fire as a controlled system with certain parameters (temperature, heating rating, velocity of propagation along the mine working) that predetermine selection of methods and combination of the fire-fighting means, guaranteeing the maximum possible fire-fighting efficiency for each concrete fire is worked out. The modern high-efficient fire-fighting system, САП type, and its modifications are developed, tested and introduced in the industry. The system can "recognize" at the early stage and fight the underground fires of the А, В, С classes and ignitions of the electrical equipment being at the voltage up to 1140 V. Procedure of calculation of the principal parameters of the mine automatic plants forming a part of the fire-fighting systems, САП-1 type, were carried out that confirmed their reliability and high fire-fighting efficiency. They can be used most efficiently and expediently for fire protection of mine electric substations and electric locomotive garages, tower-type headgears and administrative and service centres of the mines. There are more than 50 automatic systems, САП type, in the coal mines of Ukraine and Russia in operation at present.