Research On Methods And Key Technologies Of Safely Detecting And Monitoring For Dangerous Environments Based On Fiber Optic Sensing Technology

Dangerous environment is highly critical safety accident place, which will endanger the human life and social security. It is necessary to establish a scientific and rigorous security management system that effectively prevents the major accident. Meanwhile, utilizing new and advanced technologies and establishing perfect, effective security monitoring systems and enhance the ability of self-defence and self-help.For signal detecting in dangerous environment, problem of traditional electrical sensors are long-term stability, durability and distributed measurement. Especially the detection and transmission of electrical signal introduce electricity into dangerous areas, which can not basically avoid the potential danger. Optic fiber sensing technology efficiently conquers the deficiency of the electrical sensing system, especially its feature of intrinsic safety. This affords a promising technical solution to detect security parameter in dangerous environments.With the financial support from national MOST including the 863 project "fiber grating sensing technology and its industrialization" and the new production project "fiber grating temperature sensing for fire alarm system", under my tutor's guidance in 5 years, security monitoring, optic fiber sensing technology and optic fiber sensing security system are studied in basic theory, basic approach, key technologies and engineering application. These resolve the major technology problem of dangerous environment security monitoring and satisfy the industry safety production and the networking information management. Many items of the research work in this paper has passed the judgment and has widely used in industry production providing a new resolvent for security production management in dangerous environments.This paper studies the security monitoring basic method and theory in dangerous environment. The security monitoring parameter and existing method are analyzed; problems and its solutions way that influent the reliability of monitoring system are discussed. Optic fiber sensing technology in dangerous environment is studied; the requirement of sensor explosive proof feature is discussed based on the intrinsic safety feature of sensors. The principle and catalog of the optic fiber sensors are introduced and several different kinds of optic fiber sensors are compared. Key instrument of optic fiber monitoring technology in dangerous environment is discussed, including fiber grating temperature sensing fire alarm and its system, fiber grating strain sensors, fiber liquid level meters and fiber gas detectors. Meanwhile, the signal sampling and transmission technology in dangerous environment are reviewed, including the optic fiber sensing network data transmission technology based on the MODBUS field bus technology, which is the basic of optic fiber security monitoring technology in dangerous environments.The theory of security monitoring system in dangerous environment based on the optic fiber sensing is investigated. The basic composition is discussed, the system structure of security monitoring system is established using optic fiber sensor as method to obtain security information and using computer network technology as platform. The implement technology and method are discussed, including fiber grating demodulation technology, multi optic fiber sensors system integration, signal transmission technology and its system software. The reliability of the system and material anti-jamming method, lightning protection measures are discussed in the last.The last chapter is engineering application technology of dangerous environment optic fiber sensing security monitoring system. The key technologies and implement technologies of data sampling and transmission of this system, redundance network designing, OPC technology and long-distance maintenance are studied. The application methods are studied on how to realize the oil leak check with fiber liquid level meters and fiber grating temperature sensors, the video-linked safety check with fiber grating fire annunciators and video monitors. The typical application of fiber optic security monitoring system in oil field, oil depot and tunnel validate the feasibility, practicability and security of the monitoring method and technology in dangerous environment based on optic fiber sensing.