442 / 2018-12-30 10:50:03

生物质气与煤混燃的数值模拟及燃烧分析

生物质气；混燃；数值模拟；污染物；温度分布

全体主题 > 数值模拟、建模与CFD

摘要：为了进一步提高生物质能源的利用效率，同时响应国家不断严格的排放物减排号召，国内外的部分电站锅炉开始使用生物质气化合成气与煤混合燃烧来进行发电。生物质气的掺烧必然会对电站锅炉的运行状况以及燃烧产物产生一定的影响，为了研究两者混燃后炉膛内燃烧情况的变化，利用GAMBIT软件对某电厂亚临界 300 MW 机组锅炉的炉膛结构进行网格划分，并且基于FLUENT软件，搭建生物质气与煤混合燃烧模型，分别对纯煤粉燃烧和混合燃烧过程进行数值模拟。分析生物质气喷口位置发生改变时，炉膛内的速度场、温度场、组分场以及污染物NOx的分布规律。结果表明：与纯煤粉燃烧相比，煤与生物质气混燃后的最高燃烧温度降低，炉膛出口烟温降低，NO体积分数降低；在不改变炉膛总体结构和总热量的情况下，生物质气喷口位置对炉膛内的温度分布和NO生成量有较大影响。
Abstract: In order to further improve the utilization efficiency of biomass energy, and in response to increasingly stringent call for emission reduction, some domestic and foreign utility boilers begin to use co-firing of biomass gasification syngas and coal to generate electricity. Co-firing will inevitably have a certain impact on the operation of power plant boilers and combustion products. In order to study the changes of combustion in the furnace after co-firing of biomass gas and coal, the furnace structure of a 300 MW sub-critical unit boiler in a power plant is meshed by GAMBIT software. Based on FLUENT software, the co-firing model of biomass gas and coal is built. Combustion processes of pure pulverized coal and co-firing are simulated respectively. The distributions of velocity field, temperature field, component field and pollutant NOx in the furnace are analyzed when the position of biomass gas nozzle changes. The results show that, compared with pure pulverized coal combustion, the maximum combustion temperature, flue gas temperature at the outlet of the furnace and NO volume fraction are lower, and the position of biomass gas nozzle has a great influence on the temperature distribution and NO production in the furnace without changing the overall structure and total heat of the furnace.