摘要
近年来 ,针对标识性气体的探测成为火灾探测技术中发展最活跃的领域之一。将可检测极低浓度的某一气体的光声检测技术应用于极早期火灾气体产物的检测是一个新的尝试 ,将可能实现高灵敏度、高可靠性的火灾探测。但常规光声气体检测设备结构复杂、价格昂贵 ,必须恰当的重新设计才能应用到火灾探测系统中。分析了该技术在火灾探测中应用的关键问题 ,并提出了一种利用光声腔和光源间的“自由吸收路径”进行测量的光声气体探测系统 ,避免了对光源的窄带滤波要求 ,实现了在线式的气体检测。起始状态下 ,光声腔密封有纯CO气体 ,吸收光源中 4 6 μm的辐射 ,产生一定强度的初始光声信号 ;当火灾气体产物流经吸收路径时 ,其中的CO气体吸收使到达光声腔的光辐射在 4 6 μm波长上发生衰减 ,导致光声信号减弱 ,这个信号的变化量就反映了吸收路径中的CO气体浓度。
The requirements and principles of using photoacoustic gas detection technique in fire detection area are discussed and an unusual photoacoustic gas detection system is presented. Common photoacoustic gas detection systems in laboratories are not suitable for fire warning because of their poor real-time performance and high wavelength qualification for the optical setup. Besides,they are too complex and expensive. These limitations can be solved with a different system design in which an enclosed photoacoustic cell filled with CO is used to achieve CO selection instead of optical filters or laser infrared source. Online CO measurement is realized in an exposed absorption path between the cell and the IR source. At first when there is no combustion gas in the absorption path,the CO cell absorbs the light radiation at 4.6 μm and gives an initial photoacoustic signal. Once combustion gases pass through,the contained CO composition can reduce the radiation that reaches the cell at 4.6 μm and accordingly attenuate the initial photoacoustic signal. Thus CO selection in the absorption path is achieved by enclosed CO itself in the cell,and the photoacoustic signal attenuation further indicates the CO concentration in the absorption path.
出处
《中国工程科学》
2004年第7期60-64,共5页
Strategic Study of CAE
基金
中国科学院知识创新方向性资助项目 (KGCX2 -3 0 8)
九七三国家重点基础研究发展规划资助项目 (2 0 0 1CB40 960 8)
关键词
火灾探测
光声
气体检测
fire detection
photoacoustic
gas detection
