An experimental investigation about influence of chlorine content on transfer characteristic of sodium and calcium in Zhundong coal

doi:10.16085/j.issn.1000-6613.2017.02.018

Abstract

Abstract: The influence of chlorine content on transfer of sodium and calcium during combustion of Zhundong coal is conducted by the equilibrium experiment with inductively coupled plasma and atomic emission spectrum(ICP-AES),X ray diffraction analysis and horizon tube furnace. Results show that the chlorine content in Zhundong coal can promote the volatilization of sodium. The escape rate of sodium rises from 76.6% to 92.9% when PVC content increases from 0 to 0.6wt.%. More sodium chloride is produced and then transported into gas phase due to the higher concentration of sodium and chlorine,and the sulfate formed by votatile sodium and SO₂/SO₃ sticks on the tube wall between 450℃ and 650℃. Consequecely,the initial contamination layer is formed. Chlorine content in Zhundong coal has little effect on the migration of calcium because calcium salt is stable and difficult to volatilize. Only around 5% of the calcium volatilizes into gas phase and only 0.7% of calcium is absorbed by the water washing system. Around 3% of calcium sticks on the wall to form a slagging layer. This paper provides data support and theoretical guidance in solving or relieving slagging problems during combustion of Zhundong coal.

Key words: coal, Zhundong coal, chlorine, sodium, calcium, transfer characteristic

摘要： 借助电感耦合等离子体原子发射光谱仪、X射线衍射仪及管式炉实验系统，通过钠、钙平衡实验研究氯元素对准东煤中钠、钙迁移规律影响。结果表明：氯元素的含量对准东煤中的钠元素迁移起促进作用，随着聚氯乙烯（PVC）添加量从0增加到0.6%（质量分数），钠的逃逸率从76.6%升高至92.9%，这是由于更多的钠元素与氯元素结合形成氯化钠进入气相中，且逃逸出来的钠元素会与SO₂、SO₃等形成硫酸盐并在管壁温度450~650℃的管壁上沾污，形成沾污初始层；氯元素的含量对准东煤中钙元素迁移规律的影响不大，因为钙盐稳定不易挥发，仅有5%左右的钙挥发进入气相，且最多仅有0.7%的钙被尾部水洗装置吸收，剩余的3%左右的钙会沉积在管壁上，形成结渣层。为解决或减轻准东煤结渣问题提供数据支撑及理论指导。

关键词: 煤, 准东煤, 氯, 钠, 钙, 迁移特性

CLC Number:

TK534

KOU Xuesen, JIN Jing, LIU Dunyu, ZHONG Chengpeng, WANG Yongzhen. An experimental investigation about influence of chlorine content on transfer characteristic of sodium and calcium in Zhundong coal[J]. Chemical Industry and Engineering Progree, 2017, 36(02): 525-529.

寇学森, 金晶, 刘敦禹, 钟程鹏, 王永贞. 氯元素含量对准东煤中钠、钙迁移特性影响实验研究[J]. 化工进展, 2017, 36(02): 525-529.

References

[1] 石新安. 浅谈如何提高准东煤掺烧比例[J]. 中小企业管理与科技(下旬刊),2012(3):202-202. SHI X A. Discuss how to improve the blending proportion of Zhundong coal[J]. Management & Technology of SME,2012(3):202-202.
[2] LI G,WANG C,YAN Y,et al. Release and transformation of sodium during combustion of zhundong coals[J]. Journal of the Energy Institute,2015,29(1):48-56.
[3] ZHANG X,ZHANG H,NA Y. Transformation of sodium during the ashing of Zhundong Coal[J]. Procedia Engineering,2015,102:305-314.
[4] 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.
[5] 姚宇翔,金晶,钟程鹏,等. 准东煤中钠的赋存形态及挥发特性[J]. 煤炭转化,2016,39(1):1-5. YAO Y X,JIN J,ZHONG C P,et al. Occurrence mode and olatilization characiteristic of sodium in zhundong coal[J]. Coal Convertion,2016,39(1):1-5.
[6] 汉春利,张军,刘坤磊,等. 煤中钠存在形式的研究[J]. 燃料化学学报,1999,27(6):575-578. HAN C L,ZHANG J,LIU K L,et al. Mode of occurrence of sodium in coals[J]. Journal of Fuel Chemistry and Technology,1999,27(6):575-578.
[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 X F,LIU T F,HUANG J X,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] 丁一. 生物质衍生燃料气化过程中碱金属/氯的形态转化与赋存特性[D]. 沈阳:沈阳航空航天大学,2014. DING Y. Study on the transformation of alkali metals and chlorine during co-gasification of biomass and plastic[D]. Shenyang:Shenyang Aerospace University,2014.
[9] 徐旭,蒋旭光,何杰,等. 煤中氯赋存形态的试验研究[J]. 煤田地质与勘探,2002(4):3-6. XU X,JIANG X G,H J,et al. Experimental research on present form of chlorine in coal[J]. Coal Geology & Exploration,2002(4):3-6.
[10] 杨天华,丁一,开兴平,等. 水稻秸秆与PVC塑料共气化过程中钾、钠、氯的迁移行为[J]. 燃料化学学报,2014,42(3):336-342. YANG T H,DING Y,KAI X P,et al. Transformation of K,Na and Cl elements in the co-gasification of rice straw and PVC[J]. Journal of Fuel Chemistry and Technology,2014,42(3):336-342.
[11] 陈兢,傅培舫,张斌,等. 生物质燃烧中碱金属和氯沉积烧结行为分析[J]. 工程热物理学报,2014(7):1453-1456. CHEN J,FU P F,ZHANG B,et al. Deposition and sintering behavior of alkali metals and chlorine in biomass combustion[J].Journal of Engineering Thermaphysics,2014(7):1453-1456.
[12] DAYBELL G N,PRINGLE W J. The mode of occurrence of chlorine in coal[J]. Fuel,1958,37:283-289.
[13] COX J A. Chemical,extraction-based and ion chromatographic methods for the determination of chlorine in coal[M]//Coal Science and Technology,New York:Elsevier Science Publishers,1991:31-38.
[14] QUYN D M,WU H,BBATTACBARYA S P. Volatilisation and catalytic effects of alkali and alkaline earth metallic species during the gyrobIsis and gasification of Victorian brown coal. Part II. Effects of chemical form and valence[J]. Fuel,2002,81(2):151-158.
[15] TAKARADA T,ISBIKAWA H,ABE H,et al. Coal science and technology[C]//24. Proc Eighth Int. Conf. Coal Sci.,1995:687.
[16] VALAMARI T. Potassium behaviour during combustion of wood in circulating fluidised bed power plants[J]. Dissertation. Technical Research Center of Finland. VTT publications 414. Espoo Finland,2000.
[17] ROINE A. HSC Chemistry for Windows V.4.1. Chemical reaction and equilibrium software with tbennocbemical database[J]. Finland:Outokumpu Research Oy,1999.