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Study of the Accuracy of Methane Concentration Forecasts in the Area of Longwall Outlet B-3 in Seam 407/1 in KWK “Borynia-Zofiówka” Ruch Zofiówka

Badura Henryk, Zmarzły Marian, Trzaskalik Paweł, Korshunov Aleksandr Ivanovich

New Trends in Production Engineering

2020

Vol. 3, Iss. 1

120--130

In the presented publication, an ex post forecast of methane concentration at the airway outlet was carried out on the basis of equations previously developed and repeatedly tested by H. Badura and its errors were calculated. This forecast was considered as a reference level. Next, using the same forecast equations, the forecasting of methane concentration at the sensor location up to 10 m in front of the longwall face and at the longwall outlet was carried out, followed by the analysis of forecast errors. Since the measurement of methane concentrations in the locations under consideration differed, the results of forecasts also differed. Therefore, in order to assess the accuracy of forecasts, their absolute and relative errors were calculated and then compared with the forecast errors at the airway outlet. The analysis of errors showed that there are differences in forecast accuracy and it is advisable to develop new forecast equations mainly for the longwall outlet, but also for the location of methane concentration sensor installed in the airway up to 10 m in front of the longwall.

Comparative analysis of methane concentration near the junction of the longwall and top road

Zmarzły Marian, Trzaskalik Paweł

Management Systems in Production Engineering

2019

nr 3 (27)

166--173

Mining of longwalls ventilated by the „U” method is willingly applied in Polish coal-mines due to low costs of workings maintenance, low costs of ventilation and a lower fire threat because of a limited flow of air through goafs. However, such a way of ventilation may pose an increased risk of methane explosion. For this reason, the “U” ventilation has been limited in longwalls with methane risk. The mining regulations in force provide that ventilation methane-bearing capacity, i.e. the intensity of methane flow into the ventilation air cannot exceed 20 m3 CH4/min. The regulations also provide that in the event the absolute methane-bearing capacity, i.e. a sum of methane released to the ventilation air and captured by the methane drainage system is higher than 25 m3 CH4/min and the “U” method of ventilation is applied, the effectiveness of methane drainage should be minimum 50% in relation to the forecast absolute methane-bearing capacity. To streamline the process of ventilation near the junction of the longwall and the gallery carrying off the used air, auxiliary ventilation means are applied, such as a ventilation partition, a ventube – which supplies air without methane or with a low concentration of methane, injectors etc. Application of these means is limited by the cross-section of the heading carrying off the air from the longwall. Deformations of the ventilating roadway, which is usually located in the one-sided vicinity of goafs, may prevent the use of a ventilation partition, which has a negative influence on the conditions of ventilating the junction of the longwall and ventilating roadway. The author of the article also refers to such conditions, presenting average values and maximum concentrations of methane concentrations recorded with four methane concentration sensors, located in the vicinity of the junction of the longwall and ventilating roadway.