Study On Temperature Field Measurement In Biomembrane Reactor Based On The Method Of Fiber Bragg Grating

Trickling biofilter reactor is an extremely complex system which is composed of biochemical reactions, multiphase fluid flow, heat and mass transfer. And fluidic multiphase flow and transmission property are closely associated with the characteristics of biochemical reaction in the packing column. The paper has researched the literatures including domestic and international theories and experiments, and concluded that the trickling biofilter can be dynamically controlled and the treatment efficiency of the trickling biofilter will be affected by the thermophysical parameters including the system temperature field, concentration and velocity field of organic wastewater, gas velocity and concentration field and pressure field in the reactor etc. these parameters are of complexity, spatial distribution and dynamic characteristic of the time. Simultaneously, the organic matter diffusion comprising velocity field, density field even the biofilm thickness in the biofilm has been directly or indirectly affected by the parameters. Eventually, the affection has given rise to the degradation efficiency of the trickling biofilter for treating the organic wastewater. The biochemical reactions process is of considerable complexity and uncertainty in the biofilm reactor, which increases the difficulty to study the mechanism and optimal control process. The temperature field of reactor has been researched by the technology of distributed fiber Bragg grating (DFBG), a theoretic model has been established for describing temperature distribution of the reactor, and the cross-sensitivity characteristic of fiber Bragg grating (FBG) on temperature and pressure was studied in the paper. The main results are as follows.①The experimental device for treating organic wastewater, and the liquid distributor and collector which accorded to the geometric characteristics of the reactor and processing object, were designed and constructed. Meanwhile, there were analyses on the degradation efficiency impact factors of the reactor.②FBG temperature sensor unit and array were designed and built. The temperature resolution, measurement error, and the functional relationship between the Bragg center wavelength drift and the temperature were researched for the sensor unit and array. The experimental results show that the resolution was 0.10℃, and measurement error was 0.20℃of the FBG temperature sensing unit and array. Besides concentrating on the cross-sensitivity characteristic of temperature and pressure for FBG, the mathematical model and simulation results were achieved. The simulation results show that the value of cross-sensitive items reached 1pm when the temperature and pressure respectively changed to 90℃and 90MPa.③According to the parameters involving thermodynamic parameters, gas-liquid- solid-biology multiphase flow parameters and structure parameters of the biomembrane reactor etc, the mathematical models of temperature and pressure distribution in the reactor were figured out which based on the models including the metabolic heat model of cell, seepage flow model of non-newtonian fluid in the capillary, and convection heat transfer equivalent model on expanding micro-plane of the capillary. Also, it focused particularly on the research of the theoretical modle between temperature distribution and degradation efficiency of the reactor.④There were experimental studies on the temperature distribution of biofilm reactor including pre-start-up, early-start-up and after stable-start-up by adopting the system of FBG temperature sensor array. The results reveal that the radial temperature difference was from 0.80℃to 1.38℃and axial temperature difference from 2.08℃to 3.04℃when the start-up was from initial to stable (120h～360h) in the packing section. While the liquid fluid was with variable velocity, the upper part temperature of the packing section changed significantly with the increase of the liquid flow rate, finally, it tended to fluid inlet temperature. The lower part temperature rised accordingly with the increase of the liquid flow rate, and it was higher than that of the upper part when the liquid flow rate reached 45L/h.