The Mechanics Research On The Pulsating Fluidized Bed

Pulsating combustion is used widely in commercial run and civil heating, because it has the merit of high combustion intensity, high combustion efficiency, perfect heat-transfer effect and low pollutant discharge. While fluidized bed combustion technology has attractive features of high heat and mass transfer, broad operating specification of elastic coefficient, large capacity of unit equipment, simple structure of equipment, low cost of manufacturing and maintenance and low pollutant discharge.This subject matter develop a novel concept of pulsating fluidized bed combustion, it is the combination of pulsating combustion and fluidized bed combustion. It is expected that the pulsating combustion can reinforce heat and mass transfer, reduce the environmental pollution, and the time using the flow field with high intensity oscillation to change the motion character of the fluid material in the bed, and then optimize the gas-solid flow of the fluidized bed.The thesis is comprised of six sections, it includes the review and summarize of pulsating combustion technology, the experimental research on the fluidization and sounding pressure characters, the experimental research on the heat transfer characters, the experimental research on the desulfurizing characters of the pulsating fluidized bed, and the numerical simulation of Rijke combustor and flow field in the pulsating fluidized bed.Pulsating Combustion Review and Summarize A critical review of the rise, development and research survey on heat transfer and desulfurization of pulsating combustion. The experimental research situation and the analytical method on the model of Rijke tube and Rijke combustor have been summarized. After analyzing the merits and drawbacks of the pulsating combustion and fluidizing combustion, it presents the research contents of this thesis.Fluidization and Sounding Pressure Characters Experimental Research on Pulsating Fluidized Bed After verifying experimentally the Rijke type self-exciting pulsating fluidized bed combustion, under different operating conditions (different empty cross-section wind speed and inaction bed height), experimental research the oscillation characters of sounding pressure in the pulsating fluidized bed. The results indicate that the sound characters in the Rijke type self-exciting pulsating fluidized bed combustor are the same with it in the Rijke type combustor, the pressure in the combustor oscillate up and down in the sinusoidal manner and the pressure is the superposition of the multiple harmonic waves. At the same time the pressure in the pulsating fluidized bed is the sum of the pressure in fluidized bed and the one in the Rijke type combustor.Heat Transfer Characters Experimental Research on Pulsating Fluidized Bed Under different empty cross-section wind speed and inaction bed height, research the heat transfer characters between the bed and the wall, the high temperature gas and the horizontal tube with pulsating or not. The results indicate that the heat transfer coefficient increase about fourteen percent between the bed and the wall and the one between the gas and horizontal tube increase about twenty two percent, it means pulsating promote heat transfer,Desulfurizing Characters Experimental Research on Pulsating Fluidized Bed With different initial SO₂ density, mean diametric of the calcium oxide and combustion temperature, the experimental results of desulfurization with pulsating or not indicate that the desulfurizing characters of the Rijke type self-exciting pulsating fluidized bed are the same with the conventional fluidized bed combustor, it is that the utilization ratio of the calcium oxide increasing with the initial SO₂ density, the desulfurizing combustion temperature has the best value and the utilization ratio of the calcium oxide reducing with the mean diametric of the calcium oxide. The utilization ratio of the calcium oxide with pulsating is high apparently than the one without pulsating.Numerical Simulation of Rijke Combustor The CFD is used to simulate the two-dimension Rijke type combustor, the simulation results have the distribution of the combustion reactant and product and the temperature in the tube, linear increase character and limited circulate character of the pressure amplitude under pulsating combustion.Numerical Simulation of Flow Field in Pulsating Fluidized Bed Under special entry conditions, the CFD is used to simulate the three-dimension fluidized bed with different oscillation intensity and frequency in order to research the effect of sound oscillation on flow field in the fluidized bed. The results indicate that the sound oscillation can make the distribution of the flow field more uniform and can promote the heat and mass transfer.The results getting form experimental research and simulation set the base to the further research and application of this new combustion technology.