【作者】 唐军；

【导师】 黄永春； 童张法；

【作者基本信息】 广西大学 ， 化学工艺， 2008， 硕士

【摘要】 燃硫炉是制糖工业中用来制备二氧化硫气体的主要设备。燃硫炉燃烧室的燃烧过程包括流体流动、传热、传质和化学反应以及它们之间相互作用的复杂的物理化学变化。长期以来,燃硫炉燃烧室结构的优化设计方法主要是依靠经验。随着燃烧学和计算流体力学的迅速发展,数值模拟在燃烧方面得到了广泛的应用,为燃烧室的结构优化设计研究提供了有力的工具。本文针对燃硫炉燃烧室的结构及硫磺燃烧的特点,建立了燃硫炉燃烧室中燃烧过程的数学物理模型。其中数学模型是以连续性方程、动量守恒方程、能量守恒方程及组分守恒方程为基础的控制方程,物理模型包括标准的k-ε湍流模型、通用有限速率/涡耗散模型、非预混合燃烧反应模型和蒸发离散项模型。并设置了合理的边界条件及模型的求解方法。通过对传统自熔式燃硫炉燃烧室中在不同过量空气系数α时的燃烧过程进行了数值模拟,得出最佳过量空气系数α为1.6,以及燃烧室中的速度场、温度场及各组分浓度场。通过对传统自熔式燃硫炉燃烧室内流场分析,结果表明其燃烧室中存在空气与燃气混合不均匀,导致燃烧不均匀,使出口燃气存在大量S₂及SO₃。在最佳的α条件下,出口燃气中,SO₂摩尔分数达到13.0%,S₂的摩尔分数达到0.011%,SO₃的摩尔分数达到0.088%。为了验证模拟方法的可行性及准确性,将模拟结果与实际运行结果进行比较,结果表明:在边界条件相同的条件下,模拟结果与实际运行结果吻合良好,说明模型的选择是合理的,模拟方法是可靠的。为克服传统自熔式燃硫炉的缺陷,本文选用旋风燃烧方式对硫磺燃烧进行数值模拟研究。由旋风炉的燃烧特性设计出燃烧量6吨/日的立式旋风燃硫炉,通过对立式旋风燃硫炉二次燃烧室在不同过量空气系数α时的燃烧过程进行了数值模拟,得出最佳过量空气系数α为1.10,以及燃烧室中的速度场、温度场及各组分浓度场。通过各流场分析及利用数值模拟方法对二次燃烧室的结构进行了优化,得到最优结构参数为:增加过度环型燃烧室（过度角45°）、混合燃气进口直径d₁为0.125 m、二次空气进口直径d₂为0.065m、前后燃烧室直径比为1:0.80、二次空气进口高度h为0.80 m。在最优结构参数条件下,出口燃气中SO₂、S₂、SO₃的摩尔分数分别为18.8%、0%、0.0188%。通过对比传统自熔式燃硫炉与立式旋风燃硫炉的燃烧过程的模拟结果,表明:旋风立式燃硫炉燃烧室内气体混合均匀,燃烧更完全,出口燃气中S₂为零,有极少的SO₃生成,SO₂浓度更高。达到了减少燃烧室中S₂和SO₃的含量,从而提高SO₂含量的优化设计的目的。更多还原

【Abstract】 The brimstone furnace is one of the main installations in producing the sulphur dioxide in sugar production project. And the combustion is an important part of brimstone furnace. In studying the combusting process of the combustion chamber in the brimstone Furnace, theories of dynamics, heat transfer, and chemical reaction have to be applied. In the past, the design of the combustion chamber always depended on experience. However, with the rapid development of the numerical simulation in combustion, it provide strong tool for structure optimization and design.Based on the structure of combustion chamber and the character of combustion, the mathematical and physical models were established. The mathematical models mainly consist of continuity equation, momentum equation, energy equation and component equation. Thephysical models include standard k -εturbulence model, finite-rate or eddy-dissipationmodel, non-premixed combustion model and evaporation discrete phase model. The boundary conditions and solving method of model were set up.The combustion process in traditional self-fluxing brimstone furnace was simulated by computational fluid dynamics method. Under the different excess air ratio, obtained the optimum excess air ratio with 1.6 and the velocity field, the temperature field and the mass fraction field in the combustion chamber. The velocity field, the temperature field and the mass fraction field in combustion process were analyzed, and it is discovered that there are not well for mixing in the traditional self-fluxing brimstone furnace and have a quantity of SO₂, S₂, and SO₃ at the exit of furnace. Under the optimum excess air ratio, the molar fraction of SO₂, S₂, and SO₃ respectively achieve 13.0%, 0.011% and 0.088%. In order to prove numerical simulation method feasibility and the accuracy, the simulation results were compared with actual results. The numerical simulation results showed reasonably good agreement with the actual data under the same boundary conditions. The results showed that it was reasonable for choosing the model and the simulation method.In order to overcome the flaw in traditional self-fluxing brimstone furnace, the combustion process by using the way of cyclone borning was studied on numerical simulation. The 6 t/d vertical cyclone brimstone furnace was designed according to vertical cyclone boiler’s combustion characteristic.The combustion process in the vertical cyclone brimstone furnace was simulated by numerical simulation under the different excess air ratio. It was obtained the optimum excess air ratio with 1.6 and the velocity field, the temperature field and the mass fraction field in the secondary combustion chamber.Then the secondary combustion chamber was optimized by numerical simulation. The optimal structure parameters were obtained and as follows: increasing excessively annular combustion （excessive angle 45°）,the mixing fule gas’s import diameter 0.125 m,the secondary air’s import diameter 0.065 m,the pretage combustion and the postpositioned diameter ratio 1/0.80 and the secondary air’s import high 0.80 m. Under the optimal structure parameters, the molar fraction of SO₂, S₂, SO₃ respectively achieve 18.8%, 0% and 0.0188%.By the result in vertical cyclone brimstone furnace constrasted with the result in traditional self-fluxing brimstone furnace, the conductions were obtained that the combustion efficiency in vertical cyclone brimstone furnace was higher than that in the traditional self-fluxing brimstone furnace. In the vertical cyclone brimstone furnace the quantity of S₂ was zero and the quantity of SO3 were very few. It can be concluded that the vertical cyclone brimstone furnace is better the traditional self-fluxing brimstone furnace.更多还原