Reaction kinetics calculations of gaseous NaCl sulfation pathway when burning high alkali coal

doi:10.16085/j.issn.1000-6613.2017-1394

Abstract

Abstract: In order to study the sulfation paths of gaseous sodium chloride in high alkali coal flue gas and the factors influencing the sulfation ratio,the sulfation process of gas sodium chloride in flue gas under different working conditions was calculated based on the chemical reaction kinetics theory. Each reaction in the system was analyzed by using the rate of production (ROP)method. The results showed that the gaseous sodium chloride was mainly sulfated by formation of NaHSO₄ and NaSO₄ and both of them can be formed by several paths. The sulfation paths of NaCl in middle temperature region was more than that in the high temperature region for the reason that more gaseous sodium species can stably exist in the medium temperature,while the decomposition rate of NaO₂ and NaSO₃Cl was higher in the high temperature region. Increasing excess air coefficient, coal sulfur content and coal moisture content will promote the sulfation process of gaseous sodium chloride, while increasing the flue gas temperature will significantly decrease the sulfation ratio of gaseous sodium chloride mainly due to that the decomposition rate of gaseous sodium species increased under the high temperature region, leading to the decrease of sulfation paths.

Key words: coal combustion, high alkali coal, sodium chloride(NaCl), sulfur trioxide(SO₃), gaseous sulfation, reaction kinetics

摘要： 为研究高碱煤烟气中气相NaCl生成硫酸钠的途径以及硫酸化比例的影响因素，对不同工况下高碱煤理论烟气中气相NaCl的硫酸化过程进行了计算，使用生成速率（ROP）分析法对体系中各基元反应进行了分析。结果表明，烟气中的NaCl主要是通过生成NaHSO₄和NaSO₄两种前体物质进行硫酸化，两种硫酸钠前体物质均可通过多个途径生成；在中温区域多种含钠中间物质均能够稳定存在，而在高温区域NaO₂、NaSO₃Cl两种物质由于分解速率较大不能稳定存在，所以中温区域NaCl硫酸化途径多于高温区域；增加过量空气系数、煤种含硫量、煤种水分含量对NaCl的硫酸化过程均有一定的促进作用；高温区域含钠中间物质分解速度增大，NaCl硫酸化途径减少，导致高温下NaCl硫酸化比例大幅度下降。

关键词: 煤燃烧, 高碱煤, 氧化钠, 三氧化硫, 气相硫酸化, 反应动力学

CLC Number:

TK16

XIAO Haiping, QI Chao, SUN Baomin. Reaction kinetics calculations of gaseous NaCl sulfation pathway when burning high alkali coal[J]. Chemical Industry and Engineering Progress, 2018, 37(05): 1760-1766.

肖海平, 祁超, 孙保民. 燃烧用高碱煤气相NaCl硫酸化途径的反应动力学计算[J]. 化工进展, 2018, 37(05): 1760-1766.

References

[1] CROMPTON P,WU Y R.Energy consumption in China.Past trends and future directions[J].Energy Econ.,2005,27(1):195-208.
[2] 严陆光,夏训诚,吕绍勤,等.大力推进新疆大规模综合能源基地的发展[J].电工电能新技术,2011(1):1-7. YAN Luguang,XIA Xunchen,LV Shaoqin,et al.Great promotion of development of large scale integrative energy base in Xinjiang[J].Advanced Technology of Electrical Engineering and Energy,2011(1):1-7.
[3] 陈新蔚,庄新国,周继兵,等. 准东煤田煤质特征及分布规律[J]. 新疆地质,2013(1):89-93. CHEN Xinwei,ZHUANG Xinguo,ZHOU Jibing,et al.Coal quality and its distribution of the eastern junggar coalfield in junggar basin,Xinjiang[J].Xinjiang Geology,2013(1):89-93.
[4] 邱忠,梁进林. 循环流化床锅炉燃烧新疆准东五彩湾煤的对策探讨[J]. 应用能源技术,2012(12):16-19. QIU Zhong,LIANG Jinlin.Circulating fluidized bed boiler burning Xinjiang Wucaiwan area in Zhundong coal measures[J]. Applied Energy Technology,2012(12):16-19.
[5] 杨忠灿,刘家利,姚伟. 准东煤灰沾污指标研究[J]. 洁净煤技术,2013(2):81-84. YANG Zhongcan,LIU Jiali,YAO Wei. Fouling index of Zhundong coal ash[J]. Clean Coal Technology,2013(2):81-84.
[6] GE H,SHEN L,GU H,et al. Combustion performance and sodium transformation of high-sodium Zhundong coal during chemical looping combustion with hematite as oxygen carrier[J]. Fuel,2015,159:107-117.
[7] 卫小芳,刘铁峰,黄戒介,等.澳大利亚高盐煤中钠在热解过程中的形态变迁[J].燃料化学学报,2010,38(2):144-148. WEI Xiaofang,LIU Tiefeng,HUANG Jiejie,et al.Transformation of Na in an australian high-sodium coal during pyrolysis[J].Journal of Fuel Chemistry and Technology,2010,38(2):144-148.
[8] 刘敬,王智化,项飞鹏,等. 准东煤中碱金属的赋存形式及其在燃烧过程中的迁移规律实验研究[J]. 燃料化学学报,2014(3):316-322. LIU Jing,WANG Zhihua,XIANG Feipeng,et al.Modes of occurrence and transformation of alkali metals in Zhundong coal during combustion[J]. Journal of Fuel Chemistry and Technology,2014(3):316-322.
[9] 王智化,李谦,刘敬,等. 准东煤中碱金属的赋存形态及其在热解过程中的迁移规律[J]. 中国电机工程学报,2014(s1):130-135. WANG Zhihua,LI Qian,LIU Jing,,et al.Occurrence of alkali metals in Zhundong coal and it's migration during pyrolysis process[J]. Proceedings of the CSEE,2014(s1):130-135.
[10] 魏博,谭厚章,王学斌,等. 准东煤灰沉积与无机元素迁徙特性研究[J]. 工程热物理学报,2016(8):1783-1788. WEI Bo,TAN Houzhang,WANG Xuebin,et al.ash deposition and inorganic element transformation during Zhundong coal combustion[J]. Journal of Engineering Thermophysics,2016(8):1783-1788.
[11] 孙亦騄. 飞灰烧结强度测定和对煤灰沾污指数的分析[J]. 热力发电,1981(1):1-23. SUN Yilu. Determine of strength of sintered fly ash and analysis on coal ash contamination index[J]. Thermal Power Generation,1981(1):1-23.
[12] 王礼鹏,赵永椿,张军营,等. 准东煤沾污结渣特性研究[J]. 工程热物理学报,2015(6):1381-1385. WANG Lipeng,ZHAO Yongchun,ZHANG Junying,et al.Research on the slagging and fouling characteristics of Zhundong coal[J]. Journal of Engineering Thermophysics,2015(6):1381-1385.
[13] 张守玉,陈川,施大钟,等. 高钠煤燃烧利用现状[J]. 中国电机工程学报,2013(5):1-12,17. ZHANG Shouyu,CHEN Chuan,SHI Dazhong,et al.Situation of combustion utilization of high sodium coal[J]. Proceedings of the CSEE,2013(5):1-12,17.
[14] SRINIVASACHAR S,HELBLE J J,HAM D O,et al.A kinetic description of vapor phase alkali transformations in combustion systems[J]. Progress in Energy and Combustion Science,1990,16(4):303-309.
[15] LI B,SUN Z W,LI Z S,et al.Post-flame gas-phase sulfation of potassium chloride[J]. Combustion and Flame,2013,160(5):959-969.
[16] HANBY V I. Sodium sulphate formation and deposition in marine gas turbines[J]. J. Eng. Power,1974,96(2):129-133.
[17] KOHL F J,SANTORO G J,STEARNS C A,et al. Theoretical and experimental studies of the deposition of Na₂SO₄ from seeded combustion gases[J]. Journal of the Electrochemical Society,1979,126(6):1054-1061.
[18] MARTIN S,KEITH S. The chemistry of sodium with sulfur in flames[J]. Progress in Energy and Combustion Science,1990,16(4):311-317.
[19] DURI R A,MILINE J W,SMITH M Y. The deposition of salts from hydrocarbon flames containing sodium and sulphur species[J]. Combustion and Flame,1977,30:221-230.
[20] SANTIAGO J,JAVIER B. Formation and emission of submicron particles in pulverized olive residue(orujillo)combustion[J]. Aerosol Science and Technology,2004,38(7):707-723.
[21] BOONSONGSUP L,ⅡSA K,FREDERICK W J. Kinetics of the sulfation of NaCl at combustion conditions[J]. Industrial and Engineering Chemistry Research,1997,36(10):4212-4216.
[22] FIELDER W L,STEARNS C A,KOHL F J. Reactions of NaCl with gaseous SO₃,SO₂,and O₂[J]. Journal of The Electrochemical Society,1984,131(10):2414-2417.
[23] ⅡSA K,LU Y. Sulfation of potassium chloride at combustion conditions[J]. Energy Fuels,1999,13(6):1184-1190
[24] 桑倩莲,胡中发,张兰,等. 冷凝相NaCl的硫酸化动力学机理[J]. 热力发电,2015(10):41-45. SANG Qianlian,HU Zhongfa,ZHANG Lan,et al.Kinetic mechanism of sulfation of condensed sodium chlorides[J]. Thermal Power Generation,2015(10):41-45.
[25] 陶玉洁,张彦威,周俊虎,等. 准东煤在燃烧过程中的矿物演变过程及Na、Ca释放规律[J]. 中国电机工程学报,2015(5):1169-1175. TAO Yujie,ZHANG Yanwei,ZHOU Junhu,et al.Mineral conversion regularity and release behavior of Na,Ca during Zhundong coal's combustion[J]. Proceedings of the CSEE,2015(5):1169-1175.
[26] 翁青松,王长安,车得福,等. 准东煤碱金属赋存形态及对燃烧特性的影响[J]. 燃烧科学与技术,2014(3):216-221. WENG Qingsong,WANG Changan,CHE Defu,et al.Alkali metal occurrence mode and it's influence on combustion characteristics in Zhundong coals[J]. Journal of Fuel Chemistry and Technology,2014(3):216-221.
[27] PILL M J,TURANYI T,HUGHES K J.Combined mechanisms,Release3[EB/OL]. Leeds City,UK:The University of Leeds,2004.http://www.chem.leeds.ac.uk/Combustion/Combustion.html.
[28] PETER G,PAUL M. Mechanism and modeling of the formation of gaseous alkali sulfates[J]. Combustion and Flame,2005,141(1):22-39.
[29] LUSI H,FLEMMING F,HANS L,et al.An exploratory study of alkali sulfate aerosol formation during biomass combustion[J]. Fuel,2008,87(8-9):1591-1600.