Research On High Temperature Optical Fiber Sensing Technology Integrating Temperature And Pressure In Petrochemical Reactor

The simultaneous monitoring of temperature and pressure in petrochemical reactor is of great significance to ensure the safe and efficient operation of the reaction process.Traditional electrical sensors such as thermocouples and electronic pressure gauges are vulnerable to electromagnetic interference and high-temperature chemical environment,resulting in low measurement accuracy and short service life.Optical fiber sensor has the characteristics of high temperature resistance,simple structure,high measurement accuracy and anti-electromagnetic interference,but at this stage,it can only measure a single parameter of temperature or pressure.In view of this,this paper proposes and studies a high temperature optical fiber Fabry Perot(F-P)sensor and system for simultaneous monitoring of gas-liquid medium temperature and pressure in petrochemical reactor.The main research contents are as follows:(1)In view of the limitations of the existing temperature and pressure measurement technology in petrochemical industry,a high-temperature optical fiber sensor and system for simultaneous on-line monitoring of temperature and pressure in petrochemical reactor are proposed;The multi-beam interference principle and temperature or pressure sensitivity mechanism of optical fiber F-P sensor are analyzed,and the theoretical expression of its sensitivity is deduced,which provides a theoretical basis for the design of subsequent sensors.(2)Based on the sensing theory and practical application requirements of optical fiber F-P temperature pressure composite sensor,the key parameters affecting temperature or pressure sensitivity and output interference spectrum characteristics are analyzed,and the parameter indexes of F-P composite cavity under ideal conditions are obtained,and the sensitivity characteristics are verified by finite element software modeling and simulation;According to the parameter optimization,the overall structure of optical fiber F-P temperature pressure composite sensor is designed,and the preparation,packaging and aging process of the sensor are studied.(3)The signal demodulation system of optical fiber F-P temperature pressure composite sensor is built,and a variable step cross-correlation demodulation algorithm based on fast Fourier transform(FFT)is studied.The secondary development is carried out according to the software development package of photoelectric detection module,and a set of F-P composite cavity signal demodulation software is designed to realize the real-time acquisition,processing and result display of the output spectral signal of the sensor.(4)Through the experimental test and analysis of the performance of the optical fiber F-P temperature pressure composite sensing system,the results show that the temperature cavity of the sensor is only affected by the temperature in the temperature range of 20～ 600℃ and the pressure range of 0.1～5MPa,and the temperature response is a quadratic curve,which has good repeatability;The pressure chamber is affected by pressure and temperature at the same time,and the response sensitivity is0.7941μm/MPa and 0.0165μm/℃ respectively;The relative errors of temperature and pressure measurement of the sensor at 100℃,300℃ and 500℃ shall not exceed 0.896%and 2.360% respectively.The sensing system is applied to the petrochemical field to realize the remote real-time on-line monitoring of the internal temperature and pressure of the petrochemical reactor.