链条炉沼气再燃还原氮氧化物数值模拟与优化

为利用废弃沼气作为工业锅炉再燃燃料,实现对氮氧化物(NOx)的高效率还原,达到资源回收和NOx减排的目的. 联用FLIC和FLUENT软件对工业锅炉床层及炉内燃烧特性进行了模拟,进而探究了CH4/NO摩尔比、沼气稀释比和沼气喷口布置形式对炉膛内NOx还原的影响. 结果表明:CH4/NO摩尔比和两者混合程度是影响NOx还原两大主要因素,总体上NOx的还原率随着CH4/NO摩尔比和沼气稀释比的增大而升高；当CH4/NO摩尔比较小时,影响NOx还原率的主导因素是两者的混合程度；当沼气稀释到一定程度,其所具有的动量能够与主气流实现较好混合时,影响NOx还原率的主导因素是CH4/NO摩尔比；同时沼气稀释比的增大有利于减小气体不完全燃烧损失；为实现NOx高效率还原,再燃沼气喷口宜布置在前墙,但位置不宜过于偏下. 本文能够为沼气在工业锅炉燃烧及NOx还原的工业应用提供一定的参考.
In order to realize the waste biogas recycled as reburning fuel in industrial boilers aims to reduce nitrogen oxides （NOx） high efficiency, which can achieve resource recovery and NOx emission reduction. Characteristics of industrial boiler bed and furnace were simulated by combining FLIC and FLUENT software, and the effects of CH4/NO molar ratio, biogas dilution and biogas nozzles arrangement on in-furnace NOx emission were investigated. The results showed that the CH4/NO molar ratio and the degree of mixing between the two were the main factors affecting the reduction of NOx, and NOx reduction efficiency increased with CH4/NO molar ratio and biogas dilution ratio increasing in general. When the CH4/NO molar ratio was small, the dominant factor influencing NOx reduction efficiency was the mixture degree of them. When biogas was diluted to a certain degree, which could guarantee possessing sufficient momentum to mix well with the main flow, the dominant factor influencing NOx reduction efficiency was CH4/NO molar ratio. At the same time, increasing of biogas dilution ratio was beneficial to reduce the loss of gas incomplete combustion. To realize of NOx high efficiency reduction, the biomass nozzles should be arranged at the front wall, and the position should not be too low. This paper could provide some reference of biogas for industrial boilers combustion and NOx reduction.