【摘要】 基于研发6 t/h燃天然气蒸汽锅炉低NO_x燃烧器,以NO_x排放质量浓度低于30 mg/m~3为目标,进行燃气锅炉低NO_x燃烧技术的研究。简述NO_x生成机理与影响因素,提出低NO_x燃烧器的设计要点,介绍低NO_x燃烧器结构,阐述燃气和空气分级供给、分割火焰燃烧、烟气内循环、避免不完全燃烧等低NO_x燃烧关键技术的原理。低NO_x燃烧器通过采用燃气和空气分两级供给、分割火焰燃烧及两级烟气内循环等低NO_x燃烧技术,控制燃气与空气的混合过程,充分利用锅炉炉膛水冷壁冷却火焰的作用,加强烟气内循环,可以有效抑制NO_x生成。对影响NO_x生成因素进行实验研究,实验锅炉选用某锅炉房6 t/h卧式二回程燃天然气蒸汽锅炉,配置本项目研发的低NO_x燃烧器,进行燃气分级供给配比、过剩空气系数、锅炉负荷影响NO_x生成的实验。通过实验得出了影响NO_x生成的规律:降低一级燃气量的占比,可以降低火焰温度,使烟气中NO_x质量浓度降低;增大过剩空气系数,可以增加烟气内循环量,使烟气中NO_x质量浓度降低;锅炉负荷的变化会影响烟气内循环量,随着锅炉负荷增加,烟气中NO_x质量浓度先增加后降低。更多还原

【Abstract】 Based on the development of low NO_x burner of 6 t/h natural gas-fired steam boiler,the low NO_x combustion technology for gas boiler is studied with NO_x emission mass concentration lower than 30 mg/m~3. The generation mechanism of NO_x and the influence factors are sketched,and the key points of designing the low NO_x burner are put forward. The structure of low NO_x burner is introduced,and the principles of the key technologies of low NO_x combustion including gas and air staging supply,the slip flame combustion,the flue gas internal circulation and the avoiding incomplete combustion. By using the low NO_x technologies including gas and air two stage supply,the slip flame combustion and the two stage flue gas internal circulation,the generating of the NO_x can be effectively suppressed by controlling the mixing process of gas and air,making full use of the cooling flame role of water cooling wall in the boiler hearth and enhancing the internal circulation of flue gas. The experimental research on the factors affecting the generation of NO_x is performed. A 6 t/h horizontal two-way natural gas-fired steam boiler in a boiler room is chosen to be the experimental boiler,and the low NO_x burner developed by this project is installed to conduct experiments on effect of gas staging supply ratio,excess air coefficient and boiler load on generation of NO_x. The law of influencing the NO_x generation is obtained by experiments.The reduction of the primary gas ratio can decrease the temperature of the flame to reduce the mass concentration of NO_x in flue gas. The increase of excess air coefficient can increase the flue gas internal circulation to reduce the mass concentration of NO_x in flue gas. The change of boiler load can affect the flue gas internal circulation,the mass concentration of NO_x in flue gas firstly increases and then decreases with the increase of boiler load更多还原