Research On A New Flow Parameters Measurement Method Of Gas-solid Two Phase Flow

Gas-solid two phase flow is widely used in the pneumatic conveying process of the blast furnace coal powder injection process. Capacitive method is the main phase concentration measurement method of gas-solid two phase flow. The invariance of the solid phase’s permittivity is deemed to be the premise of present capacitive phase concentration measurement method. However, measurement errors of solid phase’s concentration would be caused while the solid phase’s permittivity changes. The measurement results of phase concentration are influenced by the flow patterns as well. As a result, the measurement error of phase concentration caused by the variation of the solid phase’s permittivity and changes of the flow patterns need to be compensated.Based on the experiments in the laboratory and the simulations in the finite analysis software ANSYS and the fluid analysis software FLUENT, the capacitive phase concentration sensors were analyzed and studied in this thesis. A new phase concentration measurement method which can compensate the variation of the solid phase’s permittivity was proposed; the flow process of gas-solid two phase flow in a vertical pipe was analyzed; the turbulence devices of vertical pipes were designed and optimized.The main work of this thesis is showed as follows,(1) Present phase concentration measurement method of gas-solid two phase flow was studied and analyzed by reading related literature; the compensating method of the variation of the solid phase’s permittivity was studied; a new phase concentration measurement method which can compensate the variation of the solid phase’s permittivity was proposed.(2) Capacitance sensors with parallel surface plates, spiral plates, and other structures were analyzed in ANSYS; the relationship between the sensors’output signals and the solid phase’s permittivity was analyzed and fitted.(3) The measurement results of different capacitance sensor combinations with different solid phase permittivity were simulated; structures and sizes of capacitance sensor combinations with best compensating results were obtained.(4) The flow characteristics of gas-solid phase two phase flow in the pneumatic conveying were analyzed; gas-solid two phase flow process was modeled and simulated based on the fluid analysis software FLUENT.(5) The drag force function was programmed in FLUENT to calculate the interactions between solid phase and gas phase; discrete particle model and Euler two-fluid model in the FLUENT were studied; three-dimensional flow process of gas-solid two phase flow in a vertical pipe was simulated; capacitance sensors’output signals of different flow patterns were analyzed.(6) The influence of turbulence devices with different structures on the gas-solid two phase flow were analyzed; the structures of the turbulence devices were designed and optimized by using controlling variable method and orthogonal test method; the installation position of capacitance sensors were analyzed and optimized.(7) A phase concentration measurement system of gas-solid two phase flow which can compensate the variation of solid phase’s permittivity was built in laboratory and a series of verification experiments were proceeded to verify the feasibility of this new method. The results of the experiments revealed that all the error compensating parameter were greater than 30%.In this thesis, a new capacitive phase concentration measurement method which can compensate the variation of the solid phase’s permittivity was proposed; the flow characteristics of gas-solid two phase flow in vertical pipe were analyzed; turbulence device of vertical pipe was designed and optimized. Based on the measurement system with the new phase concentration method, a series of verification experiments were proceeded. The results of the experiments revealed that all the error compensating parameter were greater than 30%.