SCR脱硝系统烟道气动流场数值研究

发布时间：2019-05-11 11:35

【摘要】：近年来,随着火电行业“超低”排放概念再次热议,氮氧化物排放要求得到了进一步提高。SCR脱硝技术由于脱硝效率高、技术成熟等优点,一直是控制NOx排放的主要选择。本文以某300MW燃煤机组SCR脱硝烟道内部烟气的流动问题为研究对象,采用Fluent软件对原始设计模型进行了气动流场数值模拟。在分析得出原型烟气分布规律的前提下,结合烟气流动特性以及压力损失变化,首先研究了扩张流道导流板与倾斜流道扰流管对喷氨系统以及反应器内速度场的影响。其次,根据喷氨混合系统存在的缺陷,通过增大涡流混合器直径、倾斜角度以及改变喷嘴位置等措施,有针对性地对原型进行了改进,优化了烟道内氨与烟气的浓度分布。最后,综合上述方案,获得速度和浓度均匀性均满足工程要求的最终优化方案。结果表明：原型流场的速度和浓度均匀性较差。增加导流板改善了扩张流道内的烟气流动,均化了速度和NH3/NO分布。扰流管改变了烟气贴壁流动规律,消除了催化剂入口速度分布不均现象,并且对压力损失和浓度均匀性影响很小。适当增加涡流混合器直径和倾斜角度可以明显增强喷氨系统氨氮的湍流掺混,结合喷嘴位置调整,明显优化了反应器内的浓度均匀性。
[Abstract]:In recent years, with the re-discussion of the concept of "ultra-low" emissions in thermal power industry, the emission requirements of nitrogen oxides have been further improved. NOx denitrification technology has been the main choice to control NOx emissions because of its high denitrification efficiency and mature technology. In this paper, the flow of flue gas in the SCR flue of a 300MW coal-fired unit is studied, and the aerodynamic flow field of the original design model is simulated by using Fluent software. On the premise of analyzing the distribution law of prototype flue gas, combined with the characteristics of flue gas flow and the change of pressure loss, the effects of diffuser guide plate and inclined channel spoiler on ammonia injection system and velocity field in reactor are studied at first. Secondly, according to the defects of ammonia injection mixing system, the prototype is improved by increasing the diameter of vortex mixer, inclined angle and changing the position of nozzle, and the concentration distribution of ammonia and flue gas in flue gas is optimized. Finally, the final optimization scheme which meets the engineering requirements is obtained by synthesizing the above scheme. The results show that the velocity and concentration uniformity of the prototype flow field is poor. The flue gas flow in the expansion channel is improved by increasing the guide plate, and the velocity and NH3/NO distribution are homogenized. The turbulent tube changed the flow law of flue gas adhesion, eliminated the uneven velocity distribution at the inlet of catalyst, and had little effect on pressure loss and concentration uniformity. Properly increasing the diameter and tilt angle of the swirl mixer can obviously enhance the turbulent mixing of ammonia nitrogen in the ammonia injection system, and the uniformity of the concentration in the reactor can be obviously optimized by adjusting the position of the nozzle.
【学位授予单位】：大连海事大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X773

【参考文献】