【作者】 石磊；

【导师】 朱曙光；

【作者基本信息】 南京理工大学 ， 热能工程， 2018， 硕士

【摘要】 选择性催化还原(SCR)脱硝烟道内首层催化剂入口处的流场均匀性对系统中烟气与氨气等还原剂的充分混合以及系统的脱硝效率有着重要影响。基于这种情况,本文首先针对实验室现有的按照某电厂实际脱硝烟道以15:1比例搭建的模化实验台进行了流场多点分区测量,结果显示其首层催化剂截面处速度分布极不均匀,速度不均匀系数Cv值较高,然后利用Fluent软件针对该模化实验台进行数值模拟,应用k-ε双方程模型模拟计算烟气的湍流运动,通过优化其内部导流板对模化实验台结构进行优化,进而研究添加导流板的位置及角度对催化剂入口流场的影响,得到优化后的导流板安装位置和角度,并对首层催化剂入口流场进行流场多点分区测量,结果表明优化后催化剂入口流场的均匀性得到了很大的改善,其Cv值小于15%,满足了催化剂层入口对流场均匀性的要求。同时,针对不同锅炉出力工况,提出了增设角度可随负荷调整的可动导流板以改善催化剂入口流场均匀性的改造方案,通过调整几块可动导流板的转动角度形成不同的导流板布置方案,可以使得各种锅炉出力工况下的首层催化剂入口截面速度不均匀系数都小于15%,并在模化实验台上进行了实验验证。最后针对国信靖江电厂实际运行中的SCR脱硝系统进行了数值模拟,同样提出了增设包含角度可调整的可动导流板在内的导流板组以改善催化剂入口流场均匀性。模拟结果表明,本文提出的可调整角度的导流板针对多种假设的不均匀入口速度场都可以将催化剂入口速度不均匀系数控制在15%以下,完全满足催化剂层对入口流场均匀性的要求,对改善催化剂层的脱硝效率有着重要的意义。更多还原

【Abstract】 The uniformity of the flow field at the inlet of the first layer of the catalyst in the SCR denitrification flue has an important effect on the full mixing of the reducing agent such as flue gas and ammonia in the system and the denitrification efficiency of the system.Based on this situation,in this paper,the multi-point measurement of the flow field is firstly performed on the laboratory’s existing modeled bench with a ratio of 15:1 according to the actual denitration flue.The results show that the velocity field of the first layer of catalyst is extremely uneven.The non-uniform coefficient of speed is high.Then this paper uses the Fluent software to perform numerical simulations on the modeling bench.The k-ε double equation model is used to simulate the turbulent motion of the flue gas,and the structure of the SCR denitrification system is optimized by optimizing the deflector plate to study the influence of the position and angle of the deflector on the inlet flow field of the catalyst.Then the paper got the optimized installation position and angle of the deflector.After that,the multi-point measurement of the flow field was performed on the inlet flow field of the catalyst.The results showed that the uniformity of the inlet flow field of the catalyst after optimization was greatly improved.Its Cv value satisfies the requirement for the uniformity of the flow field at the inlet of the catalyst layer.At the same time,for the different working conditions of boilers,an improvement plan was proposed to increase the uniformity of the inlet flow field of the catalyst by adding movable angled deflectors to adjust the boiler Ioad.By adjusting the rotation angles of several movable deflectors to form different deflectors arrangement schemes,the non-uniform coefficient of velocity of the first layer catalyst entrance under various boiler load can be less than 15%.Then,experimental verification was performed on the modeled bench.Finally,the numerical simulation of the SCR denitrification system in the actual operation of Guoxin Jingjiang Power Plant was carried out.Samely,a modification scheme was proposed to improve the uniformity of the inlet flow field of the catalyst by adding the adjustable angle deflector.The simulation results show that the adjustable angle deflector proposed in this paper can control the inlet velocity non-uniformity coefficient of the catalyst to 15%or less for a variety of assumed non-uniform inlet velocity fields,which fully satisfies the uniformity of the catalyst layer to the inlet flow field.It is of great significance to improve the life of the catalyst layer and improve the denitration efficiency of the catalyst layer.更多还原