200MW燃煤电厂SCR流场数值模拟优化与实验研究

发布时间：2019-01-17 19:52

【摘要】：目前我国对燃煤电站氮氧化物的排放控制要求日益严格，选择性催化还原（Selective Catalytic Reduction，SCR）烟气脱硝法是一种高效、成熟的技术，在国内外电厂污染物控制领域得到广泛应用。在SCR反应系统中，流场的速度分布和还原剂与烟气的混合均匀性直接决定着氮氧化物的脱除效率。本文采用CFD数值模拟及物理模型实验的方法，对某电厂200MW机组SCR脱硝工程反应系统的流场进行研究，并提出了优化方案。本文首先针对不同特点、不同结构的SCR反应器的导流装置的设计要点进行了总结。之后，对某电厂SCR反应系统的初始流场进行了模拟，分析了初始流场存在的缺陷。在此基础上，在烟道和反应器主体加设导流板组及整流格栅等装置优化速度场。根据反应器烟道结构设计喷氨格栅（AIG），以到达氨气与烟气充分混合的目的。在充分考虑系统压损及烟道安装空间后，加设静态混合器可进一步提高氨氮摩尔比的均匀程度。本文设计了一种新型静态混合器，并分别从尺寸大小、倾斜角度、安装位置三个方面进行研究，得出一种压损最小，扰流效果最强的设计方案。为确保数值模拟的正确性，根据相似原理，搭建冷态物理模型进行验证，并重点关注了飞灰的沉积情况。本文采用二氧化碳作为示踪气体，，模拟氨气与烟气混合效果；采用打孔钢板模拟催化剂层产生系统压损；采用面粉代替锅炉飞灰。对物理模型的速度场和浓度场以及烟气入射角、系统压损等进行实际测量，从而完善了数值模拟的结果，提出可运用于工程实践的设计方案。
[Abstract]:At present, the emission control requirements of nitrogen oxides from coal-fired power stations are increasingly stringent. Selective catalytic reduction of (Selective Catalytic Reduction,SCR (selective catalytic reduction) flue gas denitrification is an efficient and mature technology, which has been widely used in the field of power plant pollutant control at home and abroad. In the SCR reaction system, the velocity distribution of the flow field and the homogeneity of the mixture of reducing agent and flue gas directly determine the removal efficiency of nitrogen oxides. In this paper, CFD numerical simulation and physical model experiments are used to study the flow field of the SCR denitrification engineering reaction system of a 200MW unit in a power plant, and an optimized scheme is put forward. In this paper, the main points of design of diversion device for SCR reactor with different characteristics and different structures are summarized. Then, the initial flow field of SCR reaction system in a power plant is simulated, and the defects of the initial flow field are analyzed. On this basis, the flow guide plate and rectifier grid are added to the flue and reactor body to optimize the velocity field. The ammonia grille (AIG), was designed according to the flue structure of the reactor to achieve the purpose of fully mixing ammonia gas and flue gas. After considering the pressure loss of the system and the installation space of flue, the uniformity of ammonia nitrogen molar ratio can be further improved by adding static mixer. In this paper, a new static mixer is designed and studied from three aspects: size, inclination angle and installation position. A design scheme with minimum pressure loss and the strongest scrambling effect is obtained. In order to ensure the correctness of the numerical simulation, a cold physical model was built to verify the similarity principle, and the deposition of fly ash was focused on. In this paper, carbon dioxide is used as tracer gas to simulate the mixing effect of ammonia gas and flue gas; perforated steel plate is used to simulate the pressure loss of catalyst layer; flour is used instead of boiler fly ash. The velocity field and concentration field of the physical model as well as the incident angle of flue gas and the pressure loss of the system are measured. The results of the numerical simulation are perfected and the design scheme which can be used in engineering practice is put forward.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：X773

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