FLUENT中煤粉燃烧飞灰含碳量数值模型的改进

Improvement of the Numerical Model for Determining the Carbon Content of Flying Ash During Combustion of Pulverized Coal Contained in the Software Fluent

为了提高FLUENT软件对电站煤粉锅炉飞灰含碳量的预测精度,推导了考虑灰层扩散阻力的焦炭缩核燃烧模型,基于FLUENT软件提供的"多表面反应模型"框架,结合用户自定义函数技术对其自带的焦炭燃烧模型进行了改进。然后对某1 025 t/h电站锅炉分别采用自带和改进的焦炭燃烧模型进行模拟,并和测试结果进行了对比。结果表明:自带模型由于忽略了灰层对燃烧气体的扩散阻力,求得的飞灰含碳量仅为0.1%,改进模型求得的飞灰含碳量为3.1%,与测试结果 2.2%更为接近;自带模型和改进模型求得的炉膛出口O2体积百分比分别为3.0%和3.3%,误差在±10%范围内。

To enhance the precision predicting the carbon content of flying ash from a pulverized coal-fired boiler in a power plant by using the software Fluent,deducted was the core shrinkage model for coke with the dispersion resistance in the ash layer being taken into account and improved was the coke combustion model contained in the software Fluent by itself based on the ' multiple surface reaction' framework provided by the software Fluent and in combination with the user defined function technology. On this basis,the self-contained and improved combustion model for coke were used respectively to simulate a 1 025 t / h utility boiler and the simulation results were contrasted with the test ones. It has been found that due to the dispersion resistance of the ash layer to the combustion gas ignored by the self-contained model,the carbon content of flying ash thus obtained is only 0. 1% while that obtained by using the improved model is 3. 1%,the latter is closer to the test result 2. 2%. The oxygen volumetric percentages at the outlet of the furnace obtained by using the self-contained and improved model are 3. 0% and 3. 3% respectively,thus the error is in a range of ± 10%.