-
摘要: 以稻秸秆和玉米秸秆为原料, 考察了弱还原性气氛以及550-1300℃生物质中矿物质的变化, 并采用FactSage软件对生物质中矿物质在高温下的演变行为进行了模拟。结果表明, 生物质灰中Na和K元素的存在形式相对稳定, 部分以气态氯化物的形式挥发出去, 部分存在于低熔点硅酸盐或硫酸盐中; Si元素与Ca、Fe、Mg和Al四种元素形成的硅酸盐的变化形式较多, 主要形成辉石、橄榄石和黄长石三类物质, 随着温度的升高, 部分辉石会转化为橄榄石与黄长石, 此三类物质相互作用易形成熔点较低的共熔体而导致矿物质的熔融。方石英和莫来石是导致稻秸秆流动温度高于玉米秸秆的主要原因, 莫来石最终转化为斜铁辉石、铁尖晶石和钙长石等熔点较低的矿物质。Abstract: The composition and reaction of mineral matters in rice straw and corn stalk were investigated in weak reducing atmosphere at temperature range of 550-1300℃. The FactSage was also used to simulate the evolution behaviors of mineral matters under high temperatures. The results show that the existing form of Na and K in biomass is relatively stable, including volatilized chlorides, silicates and sulphates with a lower melting point. The silicates made up of Si, Ca, Mg, Fe and Al have various forms, mainly including pyroxene, olivine and melilite. Pyroxene is transformed into olivine and melilite with the increasing of temperature. The interaction of the three kinds of materials could result in the generation of eutectics which could lead to the melting of mineral matters in biomass. The formation of cristobalite and mullite leads to a higher flow temperature of rice straw ash than corn stalk ash, the mullite ultimately is transformed into low melting point materials like clinoferrosilite, iron spinel and anorthite.
-
Key words:
- biomass /
- mineral matter /
- ash fusion temperature /
- XRD /
- FactSage
-
图 1 不同热处理温度下稻秸秆灰的XRD谱图
Figure 1 XRD patterns of the rice straw ash produced at different temperatures
Q: quartz [SiO2]; C: cristobalite [SiO2]; Sy: sylvine [KCl]; Co: calcium oxide [CaO]; Wh: whitlockite [Ca3(PO4)2]; N: nepheline [NaAlSiO4]; Mo: monticellite [CaMgSiO4]; E: enstatite [MgSiO3]; Ce: clinoenstatite [MgSiO3]; Cf: clinoferrosilite [FeSiO3]; A: akermanite [Ca2MgSi2O7]; Si: sillimanite [Al2SiO5]; K: kaliophilite [KAlSiO4]; Cs: calcium silicate [CaSiO3]; G: gehlenite [CaAl2SiO7]; Cor: cordierite [Mg2Al4Si5O18]; Mu: mullite [Al6Si2O13]
图 2 不同热处理温度下玉米秸秆灰的XRD谱图
Figure 2 XRD patterns of the corn stalk ash produced at different temperatures
Q: quartz [SiO2]; C: cristobalite[SiO2]; Sy: sylvine [KCl]; K: kalsilite [KAlSiO4]; Co: calcium oxide [CaO]; Wo: wollastonite [CaSiO3]; Pas: potassium aluminum silicate eutectic [K0.85Al0.85Si0.15O2]; Wh: whitlockite [Ca3(PO4)2]; Ds: disodium sulfate[Na2SO4]; Ps: potassium silicate[K2Si2O5]; Fo: forsterite[Mg2SiO4]; Fa: fayalite[Fe2SiO4]; D: diopside[CaMgSi2O6]; Ce: clinoenstatite[MgSiO3]; Cf: clinoferrosilite[FeSiO3]
表 1 生物质的工业分析与元素分析
Table 1 Proximate and ultimate analysis of biomass
Sample Proximate analysis wd/% Ultimate analysis wd/% A V FC C H St N DJG 20.14 72.81 7.05 43.91 5.75 0.15 1.37 YMJG 4.27 72.00 23.73 46.91 5.24 0.12 1.28 表 2 生物质灰的组成
Table 2 Ash analysis of biomass
Sample Component w/% Na2O K2O CaO MgO Fe2O3 Al2O3 SiO2 Cl SO3 P2O5 TiO2 DJG 1.91 10.80 5.14 3.37 1.30 2.29 66.60 2.61 2.36 2.64 0.12 YMJG 0.41 26.43 14.26 9.59 0.93 0.99 36.68 4.13 2.52 3.74 0.05 表 3 生物质灰熔融特征温度
Table 3 Ash fusion temperatures of biomass
Sample Temperature t/℃ DT ST HT FT DJG 826 1010 1188 1269 YMJG 976 1033 1048 1076 Temperature t/℃ Possible reaction 550-800 quartz [SiO2]→cristobalite [SiO2], Na2O+Al2O3+2SiO2→2NaAlSiO4, 3CaO+P2O5→Ca3(PO4)2, Fe2O3+CO→2FeO+CO2, FeO+SiO2→FeSiO3, MgO+SiO2→MgSiO3, CaO+ MgSiO3→CaMgSiO4 800-900 Al2O3+SiO2→Al2SiO5, K2O+Al2O3+2SiO2→2KAlSiO4, CaO+SiO2→CaSiO3, CaSiO3+ CaO→Ca2SiO4, Ca2SiO4+MgSiO3→Ca2MgSi2O7 900-1000 Ca2SiO4+Al2O3→Ca2Al2SiO7, 2MgO+2Al2O3+5SiO2→Mg2Al4Si5O18 1000-1100 enstatite [MgSiO3]→clinoenstatite [MgSiO3] 1100-1200 2Al2SiO5+Al2O3→Al6Si2O13 1200-1300 Al6Si2O13+5FeO→2FeSiO3+3FeAl2O4, Al6Si2O13+CaO→CaAl2Si2O8+2Al2O3 表 5 玉米秸秆中矿物质在高温下可能发生的反应[9]
Table 5 Possible reactions of corn stalk mineral matters at high temperatures[9]
Temperature t/℃ Possible reaction 550-800 puartz [SiO2]→cristobalite [SiO2], CaO+SiO2→CaSiO3, 3CaO+P2O5→Ca3(PO4)2, K2O+Al2O3+2SiO2→2KAlSiO4, K2O+SiO2→K2Si2O5, Fe2O3+CO→2FeO+CO2, FeO+SiO2→FeSiO3, FeO+ FeSiO3→Fe2SiO4, MgO+SiO2→MgSiO3, CaSiO3+ MgSiO3→CaMgSi2O6 800-900 Al2O3+SiO2→Al2SiO5, K2O+Al2O3+2SiO2→2KAlSiO4, Na2O+SO3→Na2SO4, MgO+MgSiO3→Mg2SiO4 900-1100 0.15KAlSiO4+0.35K2O+0.35Al2O3→K0.85Al0.85Si0.15O2 -
[1] XIAO R R, CHEN X L, WANG F C, YU G S. The physicochemical properties of different biomass ashes at different ashing temperatures[J]. Renew Energy, 2011, 36:244-249. doi: 10.1016/j.renene.2010.06.027 [2] 马志斌, 白宗庆, 白进, 李文, 郭振兴.高温弱还原气氛下高硅铝比煤灰变化行为的研究[J].燃料化学学报, 2012, 40(3):279-285. http://rlhxxb.sxicc.ac.cn/CN/abstract/abstract17897.shtmlMA Zhi-bin, BAI Zong-qing, BAI Jin, LI Wen, GUO Zhen-xing. Evolution of coal ash with high Si/Al ratio under reducing atmosphere at high temperatures[J]. J Fuel Chem Technol, 2012, 40(3):279-285. http://rlhxxb.sxicc.ac.cn/CN/abstract/abstract17897.shtml [3] 白进, 李文, LI Chun-zhu, 白宗庆, 李保庆.高温下煤中矿物质对气化反应的影响[J].燃料化学学报, 2009, 37(2):134-138. doi: 10.1016/S1872-5813(09)60014-1BAI Jin, LI Wen, LI Chun-zhu, BAI Zong-qing, LI Bao-qing. Influences of mineral matter on high temperature gasification of coal char[J]. J Fuel Chem Technol, 2009, 37(2):134-138. doi: 10.1016/S1872-5813(09)60014-1 [4] RATALE H M, DAVID F, COLIN R W, PETRUS C P, LI Z S. Behaviour of coal mineral matter in sintering and slagging of ash during the gasification process[J]. Fuel Process Technol, 2011, 92:1426-1433. doi: 10.1016/j.fuproc.2011.03.002 [5] DU S L, YANG H P, QIAN K Z, WANG X H, CHEN H P. Fusion and transformation properties of the inorganic components in biomass ash[J]. Fuel, 2014, 117:1281-1287. doi: 10.1016/j.fuel.2013.07.085 [6] LIU B, HE Q H, JIANG Z H, XU R F, HU B X. Relationship between coal ash composition and ash fusion temperatures[J]. Fuel, 2013, 105:293-300. doi: 10.1016/j.fuel.2012.06.046 [7] 贾明生, 张乾熙.影响煤灰熔融性温度的控制因素[J].煤化工, 2007, 3:1-5. http://www.cnki.com.cn/Article/CJFDTOTAL-MHGZ200703000.htmJIA Ming-sheng, ZHANG Qian-xi. Key factors affecting fusion temperature of coal ash[J]. Coal Chem Ind, 2007, 3:1-5. http://www.cnki.com.cn/Article/CJFDTOTAL-MHGZ200703000.htm [8] THY P, JENKINS B M, GRUNDVIG S, SHIRAKI R, LESHER C E. High temperature elemental losses and mineralogical changes in common biomass ashes[J]. Fuel, 2006, 85:783-795. doi: 10.1016/j.fuel.2005.08.020 [9] 李文, 白进.煤的灰化学[M].北京:科学出版社, 2013.LI Wen, BAI Jin. Chemistry of Ash Form Coal[M]. Beijing:Science Press, 2013. [10] 乌晓江, 张忠孝, 周托, 陈玉爽, 陈国艳, 陆成, 黄凤豹.气化条件下混煤熔融特性及矿物质演变特性[J].燃烧科学与技术, 2010, 16(6):508-514. http://www.cnki.com.cn/Article/CJFDTOTAL-RSKX201006007.htmWU Xiao-jiang, ZHANG Zhong-xiao, ZHOU Tuo, CHEN Yu-shuang, CHEN Guo-yan, LU Cheng, HUANG Feng-bao. Ash fusion characteristics and mineral evolvement of blended ash under gasification condition[J]. J Combust Sci Technol, 2010, 16(6):508-514. http://www.cnki.com.cn/Article/CJFDTOTAL-RSKX201006007.htm [11] WU X J, ZHANG Z X, CHEN Y S, ZHOU T, FAN J J, PIAO G L, KOBAYASHI N, MORI S, ITAYA Y. Main mineral melting behavior and mineral reaction mechanism at molecular level of blended coal ash under gasification condition[J]. Fuel Process Technol, 2010, 91:1591-1600. doi: 10.1016/j.fuproc.2010.06.007 [12] CHAKRAVARTY S, MOHANTY A, BANERJEE A, TRIPATHY R, MANDAL G K, BASARIYA M R, SHARMA M. Composition, mineral matter characteristics and ash fusion behavior of some Indian coals[J]. Fuel, 2015, 150:96-101. doi: 10.1016/j.fuel.2015.02.015