【作者】 张彭；

【导师】 韦红旗；

【作者基本信息】 东南大学 ， 热能工程， 2017， 硕士

【摘要】 为达到超低排放的要求,燃煤机组在近期加装了 SCR脱硝装置或对已有装置进行了改造。在运行一段时间之后,发现部分机组存在较为严重的催化剂积灰、催化剂磨损以及氨逃逸的现象,导致脱硝效率降低,严重时甚至危及机组的安全运行。因此,对国内燃煤电站SCR脱硝装置所存在的问题进行研究具有重要的现实意义。本文首先对十台燃煤机组SCR脱硝装置的运行现状进行了调研。其次,在冷态通风的条件下完成了各机组SCR脱硝装置内流场的测试,同时对SCR脱硝装置进、出口截面的烟气成分进行了测量,以分析SCR脱硝装置所存在的问题与流场之间的关系。最后,使用数值模拟的手段对典型结构内部的流场进行模拟,在利用试验数据对模拟结果的正确性进行验证之后,使用数模结果对SCR脱硝装置内部的流场进行详细的分析,寻找出导致流场分布不均的结构因素并针对性提出优化方案。本文的主要结论有:催化剂入口截面烟气流场的分布不均是导致催化剂积灰与磨损的主要原因;可通过调整整流格栅的位置优化前墙侧烟气的流场;可通过调整顶棚高度差的尺寸优化后墙侧烟气的流场,顶棚高度差的最佳范围为20mm～60mm;整流格栅支撑横梁前侧流场的高速区随工字梁尺寸的减小、工字梁个数的减少以及整流格栅与上层催化剂之间距离的增加而减小。喷氨截面烟气流场宽度方向上的分布不均是导致氨逃逸以及局部脱硝效率偏低的主要原因;可通过降低省煤器出口段烟道的倾角以及扩张角,实现喷氨截面烟气流场的优化,倾角应在满足检修空间的条件下尽量减小,扩张角应选取在30°以内。更多还原

【Abstract】 In order to meet the requirements of ultra-low emissions,SCR has been equipped or transformed on coal-fired units.After a period of operation,some problems have been found like catalyst abrasion and ammonia slip.It is necessary to tudy the existing problems of SCR in coal-fired power plants.In this paper,ten SCR of coal-fired units are investigated.After then,the flow field in the SCR is tested under the condition of cold ventilation.At the same time,the flue gas composition of inlet and outlet of SCR is measured to analyze the relationship between problems and flow field.Finally,simulate the flow field in the SCR by numerical simulation.In order to find out the structural factors which leading to uneven distribution of flow field and optimiza it,analyzing the flow field inside the SCR after the correctness of numerical simulation results is verificated.The main conclusions are as follows:the problems of SCR have a close relationship with flow field.The low velocity zone on the front wall is resulted by the irrational design of the straightening gratings,and it can be achieved by optimizing the position of the straightening gratings.Catalyst abrasion on the backwall is related to the height difference between straightening gratings and ceiling,the best range is 20mm～60mm.With the decrease of the size and quantity of I-beam,the increase of the distance between straightening gratings and the first catalyzer,the high velocity zone in front of the I-beam is decreasing.Ammonia slip is resulted by the irrational design of tilt and cone angle on the flue behind economizer.When designing or optimizing the SCR device,tilt should be minimized under the condition of maintenance while cone angle should not be more than 30 degree.更多还原