Research For Monitoring Leakage Of Heating Network Based On Distributed Optical Fiber System

Distributed optical fiber temperature sensor has the advantages of simple structure,strong maintainability,anti-electromagnetic interference,good reliability and strong durability,but it is seldom used in the health condition monitoring of heating pipe network system.In this thesis,a distributed optical fiber temperature sensing system is designed according to the actual application environment of power plant,and the optical cable is laid on the hot mesh pipeline to realize the real-time and the on-line detection for temperature and position of the leakage point.At the same time,based on optical fiber sensing technology,the detection of expansion section in thermal pipeline is studied,which provides a new idea for realizing the on-line monitoring of thermal pipe network.The main research contents of this thesis are as follows: Firstly,this thesis gives an overview of the development of temperature measurement using optical fiber sensing technology at home and abroad,and expounds its application fields in detail.Combined with the existing measurement method of pipeline leakage,the unique advantages of applying this system to thermal pipeline are compared and illustrated.Then the principle of distributed optical fiber sensing technology is analyzed in detail,and three demodulation algorithms of the system are compared respectively.Combining with the theory of optical fiber sensing,this thesis introduces the main three indexes affecting the temperature measurement system,selects the hardware of the system according to the mutual restriction relationship between the indexes,and successfully builds a set of distributed optical fiber temperature sensing system based on Viso Basic development of the upper computer interface.Then the system is optimized and debugged,combined with laboratory experiments and experiments in the actual environment of power plant,the stability of the system is improved by the design of the cable laying mode and the improvement of the demodulation algorithm.This thesis focuses on the analysis of the operating state of the system in the power plant environment,and finally proves that the system can reliably and effectively realize the on-line monitoring of the thermal pipe network.Finally,through the experimental study on the on-line detection of the expansion of the expansion section of the thermodynamic pipeline network,the expansion section detection device is designed and developed,a new expansion detection model is proposed,and the establishment process of the expansion detection model is described in detail.Then the model is optimized,the expansion of expansion section is measured directly by using light intensity fitting data,and in this thesis,the measurement of expansion quantity greater than 3.3mm and the measurementerror of nearly 3% under the temperature measurement range of 36 ? to 70 ? are given.The results show that the on-line detection method of expansion section expansion proposed in this thesis can ensure that the low error is effective and feasible,and provides a high practical application value for the engineering environment.