The purpose of the work is to justification the parameters safe functioning of precinct degassing pipelines of coal mines to reduce the level accidents in the working areas and excavation sites. Object of research – the process of transporting methane-air mixture through the precinct degassing pipelines. To solve the tasks, the following research methods were used: methods calculating gas and hydraulic networks with local resistances, as well as experimental studies of changes gas-dynamic parameters gas mixture in precinct degassing pipeline with moisture accumulations, experimental studies of changes in the concentration methane in windhole, which divert air, at accumulation of liquid in the degassing pipeline. Analysis of the calculation results and experimental data allowed to justification the parameters safe functioning of precinct degassing pipelines of coal mines, to develop a methodic for calculating and controlling parameters safe transportation of methane-air mixture.
Main theoretical results: 1) aerodynamic resistance of moisture accumulation in precinct degassing pipeline is directly proportional to the time of formation the wave disturbance to liquid with maximum amplitude and varies exponentially. At this, the initial reduction in area cross section of pipeline from 50 to 80% leads to an emergency disruption it’s functioning in the range from 1 to 2 s, and the aerodynamic resistance reaches its maximum; 2) the accumulation of moisture in the precinct degassing pipeline results an exponential increase of concentration methane in the windhole in the period from 2.5 to 3 hours by a magnitude from 0.12 to 0.32% with additional her increase on 0.03-0.08% within 15 minutes after disconnecting the pipeline. Wherein, a complete stop of means of degassing leads to a similar increase in the concentration methane in excess of its safe value through 10-15 minutes and achieving stabilization level through 30 minutes or more. Scientific novelty of the results: 1) for the first time, the dependences aerodynamic resistance of moisture accumulation in the precinct degassing pipeline from time of formation a wave disturbance of a liquid with a maximum amplitude at initial reduction of the cross section pipeline, which allow to determine the time of emergency violation of its functioning; 2) for the first time are set dependencies of methane concentration in windhole from the duration deactivation of the degassing facilities and the time of moisture accumulation in precinct degassing pipeline, which allow to determine the corresponding periods and ranges changes of methane concentration. The practical significance of the results is to develop: 1) the methodical of calculation rational parameters transportation methane-air mixture in the precinct degassing pipelines which consideration flooding factor, which allows determining the parameters secure transport options gas mixture, allows determining the gas-dynamic parameters of a wet methane-air mixture in precinct degassing pipelines when their bandwidth changes, to carry out make a choice of safe parameters of gas mixture transportation, as well as the number and type of vacuum pumps; 2) the methodical of parameters control gas mixture transporting in precinct degassing pipelines with the accumulation of liquid, allows you to control the gas-dynamic parameters of a methane-air mixture in district degassing pipelines and ventilation ducts, and also to prevent the occurrence of emergency situations caused by liquids accumulations in pipelines. Research results realization. The methodical of calculating rational parameters transportation of methane-air mixture through precinct degassing pipelines, taking into account with consideration flooding fact, was used in the degassing project on PJSC «А. F. Zasyadko» (Certificate of implementation from 02.06.2015), as well as was transferred to MM «Dobropolsky» LLC "DTEK Dobropillyavuhillya" (An act of transfer from 26.03.2018). The methodical of parameters control of the gas mixture transporting in the precinct degassing pipelines with the accumulation of liquid was transferred to SE «Selidovugol» (An act of transfer from 04.04.2018). The overall expected economic effect from introduction of methodicals was 874614 UAH per year. Results of work it is advisable to use in coal mines, design and a research institute that are engaged in the development of methods for calculating underground and terrestrial gas pipelines, methods and means their control, security of transportation and utilization methane for coal deposits and also the safety labor in the coal industry.
