火电厂水媒式烟气加热器烟道优化数值模拟  

Numerical simulation on optimization for MGGH flue in thermal power plants

作　　者：郭艳玲 

机构地区：[1]中国大唐集团科学技术研究院有限公司西北分公司,陕西西安710065

出　　处：《热力发电》2018年第1期72-77,共6页Thermal Power Generation

摘　　要：目前国内火电厂烟道优化研究多数针对主流超低排放改造的烟道,缺乏对新兴余热利用设备的烟道优化分析,未深入考虑烟道设计对设备换热的影响。某600 MW火电机组水媒式烟气加热器(MGGH)烟道设计不合理,导致系统阻力大、机组带负荷能力不足。对此,本文采用CFD数值模拟方法分析该MGGH烟道流场,模拟结果与试验结果吻合良好,在判断其烟道设计问题基础上,提出了3种烟道优化方案,可有效改善MGGH前烟道流场,实现MGGH入口截面流速偏差减小6百分点,利于提高换热均匀性。3种烟道优化方案分别可降低阻力11.6%、16.0%、45.6%,其中优化方案3综合提高了MGGH前、后烟道的流动均匀性,尤其对烟箱内流场改善效果良好,烟道总阻力减少448 Pa,比改造前降低了45.6%,预计风机能耗降低10%,可达到提升机组带负荷能力的目的。Currently, most of the research on flue optimization in domestic thermal power plants mainly focuses on ducts for main ultra-low emission reconstruction, while that for flue duct in emerging energy-saving equipments is rarely studied, and without deeply considering the influences of flue design on heat transfer of the equipments. High pressure drop and insufficient load capacity occurred on a 600 MW thermal power unit due to unreasonable MGGH flue design. To solve this problem, the field flow of this MGGH flue was simulated by CFD numerical methods, and numerical results agree well with the experimental data. By analyzing the flue design problems, three optimization schemes were proposed. The results show that, after the three schemes are applied, the flow field in front of the MGGH is improved and the flue velocity deviation at the MGGH inlet decreases by 6%, which benefits the heat transfer uniformity. The pressure drop under the above three optimization schemes reduces by 11.6%, 16.0% and 45.6%, respectively. The optimization scheme III remarkably improves the flow field uniformity for the MGGH flue, especially for the flue behind the MGGH. After the optimization scheme III is applied, the total pressure drop reduces by 448 Pa （45.6%）, the energy consumption of the fan is estimated to reduce by 10%, indicating the unit load capacity can be increased.

关 键 词：火电厂 MGGH 烟道优化 流场特性 CFD 流速偏差 烟道阻力 超低排放 

分 类 号：TK11[动力工程及工程热物理—热能工程]