Research And Application Of Fiber Bragg Grating Monitoring Technology For Tank Deformation

With the establishment of the National Petroleum Strategic Reserve Base and the continuous improvement of the design and construction capacity of large oil storage tanks in China,the number of large oil storage tanks put into use has increased significantly in recent years.In view of the major hazards of oil tank leakage and the lack of deformation monitoring and management of large storage tanks,it is necessary to develop a monitoring system for large storage tank deformation.In this dissertation,a commercial warehouse in Dalian,China,is taken as 10×10~4m~3.Based on the structure and material data of an external floating roof crude oil tank,the finite element simulation model is established,and the stress distribution is studied.According to the principle and characteristics of FBG sensing technology,the strain monitoring system of the tank is designed.The monitoring system is installed on a large tank model in Dalian to verify the application effect of the system.The main research contents are as follows:The ANSYS simulation software is used to study the deformation characteristics of storage tanks.The influence of secondary structure on the deformation of storage tanks is neglected in the modeling process,and the tank model is simplified to obtain the location of larger deformation degree of storage tanks.In order to calculate the deformation of the storage tank under the ultimate stress,the maximum stress intensity and the ultimate strain of the storage tank at the junction of one or two layers of panels are obtained under the condition of water pressure and butterfly settlement,which have a great influence on the deformation of the storage tank.This provides a basis for the layout of the monitoring system and the setting of alarm values.Based on the principle of fiber Bragg grating sensing technology and the general principle of monitoring system design,the special requirements of tank deformation monitoring are put forward.The structure of tank deformation monitoring system is designed by choosing appropriate hardware devices such as sensors,demodulators and software modules to meet the functional requirements,so as to prepare for the test application of the monitoring system.The designed FBG deformation detection system is applied to the model of medium-sized storage tank.According to the results of ANSYS simulation,the monitoring points of storage tanks are determined,and the monitoring network is installed according to the hardware and software structure of the designed monitoring system.Deformation is generated by step-by-step water injection pressure and simulated settlement of ground deformation.Monitoring data of sensors are obtained.Finally,monitoring data are compared with numerical simulation values to evaluate the effectiveness of monitoring system.