标题:
PC锅炉之双相流研究Solid-Air Two Phase Flow in a Pulverized Coal Boiler
作者:
张育诚, 吴国光, 焦鸿文, 郑景亮
关键字:
双相流, 粉煤管, 锅炉Two Phase Flow; Pipeline; Boiler
期刊名称:
《Sustainable Energy》, Vol.2 No.1, 2012-01-18
摘要:
PC锅炉(pulverized coal boiler)在燃烧之前，粉煤是以气体输送方式进入燃烧机，其过程是藉由固气双相流动模式，而固气双相流分析相当复杂，特别是粉煤流经弯管时，由于粉煤在管中流动不是均匀分布于其管路截面，因而产生集中于管路某侧的现象。这将造成空气与粉煤无法充分混和燃烧，导致过量之过剩燃烧空气及提高未燃碳损失。因此，若能了解粉煤在空气管流中的分布情形，将有助于提升整体锅炉燃烧效率及减少氮氧化物的排放。本研究藉由一座实厂前墙式燃煤锅炉，上、下两排共计四支燃烧器，满载蒸汽产量为七十吨，以工程计算流体力学软件进行粉煤管流实体网格建立，同时模拟最佳粉煤取样位置及粉煤管内空气与粉煤分布状况，藉此仿真结果，作为现场性能测试之参考依据，可提供现场锅炉运转之一次风流速与相关运转操作参数之设定。根据趋势模拟分析结果指出，等动量粉煤取样点设置点，可于粉煤管直管段3D~5D位置，此处粉煤分布状况，可降低等动量取样误差之影响。
In the case of coal-fired power plants that operate on a continuous supply of pulverised coal to furnaces, maldistribution of pulverised fuel often occurs as coal particles are pneumatically transported from the mill through ducts consisting of numerous bends and straight sections. The study was carried out on a coal-fired boiler with capacity of 70 tons of steam per hour. Iso-kinetic sampling of pulverized coal was performed to find out the airflow rate and coal flow rate in the two-phase flow. With baseline operation parameters from a cogeneration boiler, computational fluid dynamics (CFD) software was used to simulate the two-phase flow. Based on simulation results, the best sampling point was the location of 3D - 5D straight pipeline. The influence of sampling error was minor in these locations.