高压电力电缆隧道火灾早期预警判据的实验研究

我国城市架空高压电力线路已逐渐下地进入电缆隧道,其中的火灾防控系统是保护整个电力输送安全与稳定的重要一环。搭建了高压电力电缆隧道火灾烟气模拟与测量实验平台,针对电缆受热着火燃烧的典型工况,研究了隧道两端不同开口状态下的顶棚各位置CO浓度、CO2浓度、烟颗粒浓度和温度的变化特征。结果表明,顶棚位置CO浓度和烟颗粒浓度可作为火灾早期预警的优选标志性参数,而CO2浓度和温度较不适合。设定CO浓度和烟颗粒浓度的预警阈值分别为10 ppm和0.05 dB/m,各顶棚位置均可实现报警,各工况下,不同顶棚位置报警时间呈以火源正上方探头为最早报警的V字形分布。此外,电缆隧道两端的开口状态对隧道内CO和烟颗粒运动产生一定影响,进而影响不同预警参数的响应灵敏度,即两端开口时,CO浓度预警模式更早响应,而两端关闭时,烟颗粒浓度预警模式更早响应。研究结果对高压电缆隧道火灾预警系统的设计具有指导作用,也可为未来高压电缆隧道的相关预警标准提供基础。

Experimental study on the criterion for early fire detection in high-voltage cable tunnel

More and more overhead high-voltage power cables have been in underground tunnels in the past decades in China. The fire protection system plays an important role in safe and steady power transportation. An experimental setup is developed to investigate the typical signals during the early stage of a cable fire in an underground tunnel. The detailed CO, CO2, smoke density, and temperature near the tunnel ceiling for smoldering and flaming cable fires are measured with various opening conditions in the tunnel. The results indicate that the signals of CO and smoke density below the ceiling are suitable for early fire detection of cable fire in the tunnel, while the signals of CO2 and temperature cannot be used. Most sensors with different distances to fire sources can release reliable alarms if the criteria of CO and smoke density are set as 10 ppm and 0.05 dB/m, respectively. The sensor above the fire would respond first. Additionally, the CO and smoke transportation behaviors depend on the opening conditions of the tunnel, with varied responding sensitivity between detectors of CO and smoke density. Specifically, CO detectors respond early with the tunnel opening at two ends, while smoke detectors give an early alarm for the closed tunnel.