煤和石油焦混烧过程NO生成规律实验
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摘要
石油焦是石化行业常用的固体燃料,通常以和煤混烧的形式加以利用,由于其硫分高,一般需采用石灰石炉内脱硫工艺,而添加石灰石以及燃烧中产生的各种固相物质可能会对氮氧化物的排放产生影响。为了探索这方面的规律,在水平管式炉反应器上研究了石灰石、煤灰、石油焦灰、飞灰、底渣以及炉膛内固相物质在煤和石油焦混烧过程对NO生成的影响。结果表明:CaO可以缩短焦炭的燃尽时间,也可以抑制SO_2的生成;石灰石对NO生成有显著的促进作用,这是由石灰石本身或者石灰石的分解过程造成的;含Fe、V、Ni较多的煤和石油焦的灰也可以明显促进NO的生成;而飞灰、底渣以及炉膛中部飞灰对NO的生成影响不明显。该结论有助于理解煤和石油焦燃烧过程中固相物质对氮氧化物排放的影响,对采取合理措施降低氮氧化物排放有积极意义。
Petroleum coke is a common solid fuel of petrochemical industry and is usually used in the form of co-combustion with coal. Because of its high sulphur content, limestone is often employed to capture SO_2.Meanwhile, limestone and various solid materials generated during the combustion process may influence the emission of NO_x. To investigate this influence rules, the effects of limestone, coal ash, petroleum coke ash, fly ash,slag and solid materials on NO formation during co-combustion of coal and petroleum coke are studied on a horizontal tube furnace. The results show that the burn out time of char is shortened and the formation of SO_2 is suppressed by CaO. Besides, the formation of NO is significantly promoted by limestone on account of limestone or the decomposition of limestone. Coal ash and petroleum coke ash with abundant Fe, V and Ni can also promote the formation of NO. While the effects of fly ash, slag and furnace ash are not obvious. This result is conducive to understand the effects of solid materials on NO formation during co-combustion of coal and petroleum coke, and is of positive significance for taking reasonable measures to reduce NO_x emission.
Petroleum coke is a common solid fuel of petrochemical industry and is usually used in the form of co-combustion with coal. Because of its high sulphur content, limestone is often employed to capture SO_2.Meanwhile, limestone and various solid materials generated during the combustion process may influence the emission of NO_x. To investigate this influence rules, the effects of limestone, coal ash, petroleum coke ash, fly ash,slag and solid materials on NO formation during co-combustion of coal and petroleum coke are studied on a horizontal tube furnace. The results show that the burn out time of char is shortened and the formation of SO_2 is suppressed by CaO. Besides, the formation of NO is significantly promoted by limestone on account of limestone or the decomposition of limestone. Coal ash and petroleum coke ash with abundant Fe, V and Ni can also promote the formation of NO. While the effects of fly ash, slag and furnace ash are not obvious. This result is conducive to understand the effects of solid materials on NO formation during co-combustion of coal and petroleum coke, and is of positive significance for taking reasonable measures to reduce NO_x emission.
引文
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[2]ZHAO Changsui,WANG Wenxuan,WANG Fengjun,et al.Emission control of gaseous pollutants from co-firing of petroleum coke and coal in CFB[J].International Conference on Fluidized Bed Combustion,2003:925-934.
[3]SHEN Boxiong,LIU Dechang,CHEN Hanping,et al.A study of the mechanism of petroleum coke pyrolysis[J].Asia-Pacific Journal of Chemical Engineering,2000,8(3/4):351-358.
[4]WANG Jinsheng,ANTHONY E J,ABANADES J C.Clean and efficient use of petroleum coke for combustion and power generation[J].Fuel,2004.83(10):1341-1348.
[5]HILL J M,KARIMI A,MALEKSHAHIAN M.Characterization,gasification,activation,and potential uses for the millions of tonnes of petroleum coke produced in Canada each year[J].Canadian Journal of Chemical Engineering,2015,92(9):1618-1626.
[6]XIAO Jin,ZHONG Qifan,LI Fachuang,et al.Modeling the change of green coke to calcined coke using Qingdao high-sulfur petroleum coke[J].Energy and Fuels,2015,29(5):3345-3352.
[7]XIAO Jin,ZHANG Yanbing,ZHONG Qifan,et al.Reduction and desulfurization of petroleum coke in ammonia and their thermodynamics[J].Energy and Fuels,2016,30(4):3385-3391.
[8]SHIMIZU Tadaaki,TACHIYAMA Yutaka,KURODA Ayumu,et al.Effect of SO2 removal by limestone on NOx and N2O emissions from a circulating fluidized bed combustor[J].Fuel,1992,71(7):841-844.
[9]LUPIá?EZ C,DíEZ L I,ROMEO L M.NO emissions from anthracite oxy-firing in a fluidized-bed combustor:effect of the temperature,limestone,and O2[J].Energy and Fuels,2013,27(12):7619-7627.
[10]侯祥松,李金平,张海,等.石灰石脱硫对循环流化床中NOx生成和排放的影响[J].电站系统工程,2005,21(1):5-7.HOU Xiangsong,LI Jinping,ZHANG Hai,et al.Limestone effects on NOx formation&emission in CFB combustors[J].Power System Engineering,2005,21(1):5-7.
[11]张春林,袁贵成,刘德昌,等.石油焦流化床燃烧过程中氮氧化物的排放研究[J].电站系统工程,2003,19(1):16-18.ZHANG Chunlin,YUAN Guicheng,LIU Dechang,et al.Study on the emission of NOx and N2O during combustion of petroleum coke in a FBC[J].Power System Engineering,2003,19(1):16-18.
[12]SHIMIZU Tadaaki,FUJIKAWA Tomoyasu,TONSHO Masaru,et al.Effect of batch feeding of limestone on NOx and SO2 emissions during petroleum coke combustion in a bubbling fluidized bed combustor[J].Energy and Fuels,2001,15(5):1220-1224.
[13]COMMANDRéJ M,SALVADOR S,VAN DE STEENE L,et al.The formation and reduction of no during the combustion of powdered petroleum coke—the case of cement plant precalciner conditions[J].Combustion Science and Technology,2005,177(3):579–611.
[14]王文选,张守玉,王凤君,等.循环流化床中石油焦与煤混合燃烧NO排放特性[J].煤炭转化,2003,26(4):60-64.WANG Wenxuan,ZHANG Shouyu,WANG Fengjun,et al.Study on no emission of petroleum coke combustion blending with coal in CFB[J].Coal Conversion,2003,26(4):60-64.
[15]朱晓明.220 t/h循环流化床锅炉混烧石油焦与煤的硫/氮排放研究[J].锅炉技术,2013,44(6):25-28.ZHU Xiaoming.Sulfur/nitrogen pollutant emission from mixed combustion of petroleum coke/coal in a 220 t/h circulating fluidized bed boiler[J].Boiler Technology,2013,44(6):25-28.