高温富氧燃烧过程中煤灰特征元素对煤粉成灰特性的影响  

Influence of characteristic elements in coal on ash formation characteristics of pulverized coal under high temperature oxy-fuel combustion

作　　者：刘庄 吴晓峰 范卫东[1] 张翔[2] 刘煜[2] LIU Zhuang;WU Xiaofeng;FAN Weidong;ZHANG Xiang;LIU Yu(School of Mechanical and Power Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;Shanghai Boiler Works Co.,Ltd.,Shanghai 200245,China)

机构地区：[1]上海交通大学机械与动力工程学院,上海200240 [2]上海锅炉厂有限公司,上海200245

出　　处：《洁净煤技术》2021年第1期272-280,共9页Clean Coal Technology

基　　金：国家重点研发计划资助项目(2018YFB0605301)。

摘　　要：沾污结渣是富氧燃烧锅炉运行的主要问题之一,由于CO2和N2辐射传热和化学性质的差异,富氧锅炉内壁沾污结渣情况更加严重。近年来学者针对富氧情况下煤灰的沾污结渣情况进行了系统分析,得出了较为详实的结果,但仍缺乏富氧情况下基于煤灰内特征元素和气氛对于煤粉燃烧成灰的相关研究。选取煤粉结渣中的关键元素Ca、Na、Fe作为特征元素,选取特征元素的氧化物或氢氧化物作为添加剂,选取灰成分以Al、Si为主的山西无烟煤作为试验煤样,定量研究富氧情况下特征元素对于煤粉高温成灰特性的影响。结果表明,特征元素含量较高时,相比较空气气氛,富氧气氛下煤粉的反应时长减少20~50 min,且随氧气浓度增大,煤粉反应时长逐渐增加;高Fe煤和高Na煤的灰熔融温度比基准煤降低了150℃左右,但Ca对于煤灰的变形温度影响不明显;富氧情况下,高Ca煤中随着氧气浓度升高,出现钙硅铝酸盐和莫来石晶相,随温度升高,钙长石等硅铝酸盐生成,Na、Fe等元素非晶相化加强;高Fe煤中Fe随着氧气浓度升高从氧化物向硅铝酸铁转变,随温度升高,顽火辉石与磁铁矿含量升高,钙铁硅氧化物含量先增加后减少;高Na煤得到的低氧煤灰Na主要以霞石成分存在,氧气浓度升高导致其逐渐转化形成硅酸钠盐;随温度升高,Na的形态会从稳定的酸式盐向硅酸钠盐或其他稳定非晶体转变。Fouling and slagging is one of the main problems in the operation of oxy-fuel combustion boilers.Due to the difference in radiant heat transfer and chemical properties of CO 2 comparing to N 2,the fouling and slagging on the inner wall of oxy-fuel boilers is more serious.In recent years,scholars carried out systematic analyses on the fouling and slagging of coal ash under the condition of oxy-fuel combustion,and obtained more detailed results.However,there is still a lack of research on the ash formation of pulverized coal combustion based on the characteristic elements and atmosphere under oxy-fuel combustion.In this paper,the key elements Ca,Na,Fe in pulverized coal slagging were selected as characteristic elements,and the oxides or hydroxides of characteristic elements were selected as additives.Shanxi Anthracite with Al and Si as main ash components was employed as the experimental coal to quantitatively study the influence of characteristic elements on high temperature ash formation characteristics of coal under oxygen enrichment.It has found by experiment that when the content of characteristic elements is higher,the reaction time of pulverized coal in an oxygen-enriched atmosphere is reduced by 20-50 min compared with that in air atmosphere,and as the oxygen concentration increases,the reaction time of pulverized coal gradually increases;the ash melting point of high Fe coal and high Na coal is about 150℃lower than the benchmark coal,but Ca has no obvious influence on the deformation temperature of coal ash.At the case of oxy-fuel combustion,calcium aluminosilicate and mullite will appear in the high-Ca coal as the oxygen concentration increases,and aluminosilicate such as anorthite is formed,and the amorphous phase of Na and Fe is strengthened as the temperature increases.The Fe in high-Fe coal changes from oxide to ferric aluminosilicate as the oxygen concentration increases.As the temperature increases,the content of enstatite and magnetite increases.The content of calcium iron silicon oxide and calci

关 键 词：富氧燃烧 沾污结渣 特征元素 成灰特性 赋存形态 

分 类 号：TQ53[化学工程—煤化学工程] TK114[动力工程及工程热物理—热能工程]