烟气再循环与空气分级对氢氧化铝焙烧炉运行参数的影响  

Effects of flue gas recirculation and air staging on the operating parameters of aluminum hydroxide calciner

作　　者：李潇峰 邹俊 张扬[3] 王志宁 张海[3] 吕俊复[3] 刘青[3] 张守玉[1] LI Xiaofeng;ZOU Jun;ZHANG Yang;WANG Zhining;ZHANG Hai;LYU Junfu;LIU Qing;ZHANG Shouyu(School of Energy and Power Engineering,University of Shanghai for Science and Technology,Shanghai 200093,China;Shanxi Research Institute for Clean Energy Tsinghua University,Taiyuan 030032,China;Key Laboratory for Thermal Science and Power Engineer of Ministry of Education,Department of Energy and Power Engineering,Tsinghua University,Beijing 100084,China)

机构地区：[1]上海理工大学能源与动力工程学院,上海200093 [2]清华大学山西清洁能源研究院,山西太原030032 [3]清华大学能源与动力工程系热科学与动力工程教育部重点实验室,北京100086

出　　处：《洁净煤技术》2020年第5期127-135,共9页Clean Coal Technology

基　　金：国家自然科学基金资助项目(51706119);四川省科技计划资助项目(2018JZ0021,2019YFS04976)。

摘　　要：氢氧化铝焙烧炉常用SCR或SNCR技术降低NOx排放,但存在催化剂被污染以及氨逃逸等问题,亟待发展一条新的减排方案。烟气再循环和空气分级技术是降低氢氧化铝气态悬浮焙烧炉NOx排放的潜在手段,但烟气再循环和空气分级燃烧技术对气态悬浮焙烧炉运行参数的影响规律仍不明确。以3000 t/d规模的氢氧化铝气态悬浮焙烧炉系统为研究对象,研究了烟气再循环和空气分级对氢氧化铝气态悬浮焙烧炉运行参数的影响规律。通过计算发现,当烟气再循环率为20%时,系统总过量空气系数降低至1.1左右,可维持较大的一次风量,保证悬浮焙烧状态的同时,使主焙烧炉(P04)下部达到欠氧还原性气氛,进而抑制NOx的生成。烟气再循环率在20%且空气分级的燃尽风率在25%以内时,GSC炉系统中各分离器效率变化可忽略。GSC炉系统增加烟气再循环和空气分级后,若不调整燃料分配,焙烧温度会降低,可能对氧化铝产品质量产生不利影响。通过优化GSC炉的燃料分配,可显著降低烟气再循环和空气分级对系统运行参数的影响程度。烟气再循环达20%且空气分级的燃尽风率在25%时,优化后的GSC炉系统仍可在保证氢氧化铝焙烧工艺温度和整体热效率的情况下,实现主焙烧炉膛下部的欠氧还原性燃烧气氛,为GSC焙烧炉的低氮燃烧设计提供了必要条件。SCR and SNCR technology are commonly used to reduce NOxemission of aluminum hydroxide gaseous suspension calciners(GSC).However,due to the problems of contamination on catalyst and ammonia slip,it is urgent to develop a new scheme to reduce NOxemission.Fuel gas recirculation and air staged combustion are potential approaches to reduce NOxemissions of aluminum hydroxide GSC.However,the effects of fuel gas recirculation and air staging on operating parameters of GSC are still unclear.In the present study,taking a 3000 t/d aluminum hydroxide GSC as the research object,the effects of the flue gas recirculation and air staging on the GSC operating parameters were investigated.It is found that when the flue gas recirculation rate is 20%,the total excess air ratio of the system is reduced to about 1.1,which can maintain a large primary air volume,ensure the suspension roasting state,and make the lower part of the main roasting furnace(P04)achieve a reductive atmosphere,thus inhibiting the formation of NOx.The changes in the separation efficiency of each cyclone in GSC caused by the flue gas recirculation and air staging ware negligible when the flue gas recirculation ratio are below 20%and the over fire air ratio of the air staged combustion are below 25%.The flue gas recirculation and air staged combustion result in a decrease of the calcination temperature if the fuel distribution is not well adjusted,which may have adverse effects on the quality of alumina products.However,by optimizing fuel distribution of the GSC calciner,the influence of flue gas recirculation and air staging on operating parameters can be largely reduced.When the flue gas recirculation ratio reaches 20%and the over fire air ratio reaches 25%,the lower part of the main furnace of the GSC calciner can achieve a reductive atmosphere while the aluminum hydroxide calcination temperature and overall thermal efficiency are still ensured,which provides the necessary condition for the low-NOxcombustion design of the GSC process.

关 键 词：气态悬浮焙烧炉 烟气再循环 空气分级 物料平衡 热平衡 

分 类 号：TQ133.1[化学工程—无机化工]