摘要
燃气-蒸汽联合循环发电中燃气轮机与余热锅炉主体经常采用大扩张角过渡段连接,导致下游烟气流动不均匀,影响余热锅炉NOx选择性催化还原烟气脱硝效率.对此,提出通过布置三级导流板来改善烟道内烟气的流动均匀性,并采用计算流体力学模拟方法研究过渡段导流板布置形式、安装角度及布置密度等参数对烟道内烟气流动特性的影响规律.结果表明:未设置导流装置时过渡段出现明显漩涡,涡度可达 20 m-1,导致烟气流动均匀性差;过渡段安装一级变倾角导流板可显著抑制漩涡的尺寸,安装二级变倾角导流板可显著改善过渡段内烟气流动均匀性,但是烟道后端烟气速度均匀性仍不高,安装三级导流板可同步改善过渡段和烟道内烟气流动均匀性,在换热模块三之后相对速度标准差系数降至 2.1%.优化的导流板布置为:一级导流板水平投影长度 2.25 m,间距 1.20 m,角度15°～30°等差递增;二级导流板水平投影长度 1.36 m,间距1.40 m,角度 15°～60°等差递增;三级导流板长度0.70 m,间距1.00 m,水平安装.研究结果可为烟气均流装置的设计提供理论指导.
Abstract
In natural gas-steam combined cycle power plants,the connection section between the gas turbine and the waste heat boiler is characterized by a sharply expanded channel confined by plates with large inclination angles,which often results in unsatisfactory flow pattern and consequently leads to a reduction in deNOx efficiency in the downstream.Installation of triple layers of deflectors is proposed to improve the flue gas flow uniformity.Computational fluid dynamics modeling approach is adopted to investigate the influences of the deflector parameters including installation arrangements,installation angle and density on the flue gas flow characteristics in the flue duct.A large vortex is clearly observed in the connection section with a vorticity up to 20 m-1,when no deflector is installed.Installing a single layer of deflector with varying installation angles is able to decrease the size of the vortex,while installation of double layers of similar deflectors leads to a satisfactory flow pattern in the connection section.A more preferable flue gas flow pattern in the whole boiler channel is obtained by a setup of triple layers of deflectors.The optimal lengths projected horizontally are 2.25 m,1.36 m and 0.70 m for the three-layer deflector plates,and the distances between two plates are 1.20 m,1.40 m and 1.00 m separately.The installation angle is between 15° and 30° with uniform incrementation for the first deflector,and between 15° and 60° with uniform incrementation for the second deflector.A relative velocity standard deviation of 2.1%is obtained at outlet cross-section with the triple deflectors.The research results can provide theoretical guidance for the design of flue gas flow equalization devices
基金项目
合肥市关键共性技术"揭榜挂帅"(GJ2022QN02)
中央高校基本科研业务费专项资助(PA2023GDSK0119)
维普
万方数据