Research on the Resistance and Flame Retardant Performance of Flame Arresters in Low-Concentration Coalbed Methane...

In order to ensure the safety of the coalbed methane pump station and the underground coalbed methane extraction system, the low-concentration coalbed methane transmission pipeline needs to be installed with fire arresters. The traditional fire arrester design is not standardized, the reliability of the fire prevention effect is low, and the resistance is large. Based on the theory of flame quenching, through numerical simulation and experimental methods, this paper studies the structure of fire arresters suitable for the safety assurance system of low-concentration coalbed methane transportation, so as to provide safety assurance for the raw gas transmission of low-concentration coalbed methane utilization devices. The results are stated as follows: After the coalbed methane explosion, the flame accelerates along the direction of propagation within the pipeline. The pressure of the shock wave inside the pipeline reaches its maximum value and then decreases and stabilizes. When the flame encounters obstacles within the pipeline, there is a noticeable jump in both flame speed and pressure. Flame arresters installed in low-concentration coalbed methane utilization systems should be equipped with corrugated plate flame-arresting cores that have sufficient mechanical strength to resist the sudden increase in pressure and velocity. To accelerate the cooling of the flame during propagation and reduce resistance, the diameter of the central flame-arresting core should be sufficiently large. For the optimized DN500 dry flame arrester, the optimal diameter of the flame-arresting core is 1500 mm, the expansion angle of the flame arrester housing is 30°, the spacing between corrugated plates is 30 mm, the thickness of the corrugated strip is 0.25 mm, and the number of corrugated plates is 2. When the flow velocity of the coalbed methane is 15 m s^-1, the resistance is 670 Pa. Experimental tests have shown that when the flame propagation velocity is below 775 m s^-1, the flame arrester can successfully interrupt the flame propagation.