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题名	解耦燃烧与烟气返回降低铁矿烧结过程NOx的基础研究
作者	陈彦广
学位类别	博士
答辩日期	2008-12-28
授予单位	中国科学院过程工程研究所
授予地点	过程工程研究所
导师	郭占成
关键词	解耦燃烧 烟气返回 烧结 脱硝
其他题名	Fundamental Research on NOx Reduction by Decoupling Combustion with Recycling Flue Gas during Iron Ore Sintering
学位专业	化学工艺
中文摘要	目前，我国铁矿烧结过程NOx年排放量达100万吨以上，约占全国NOx总排放量的10%，NOx导致酸雨与光化学烟雾的形成，危害人体健康和影响生态环境，因此需要降低烧结过程NOx排放。我国烧结工序在脱硫除尘方面做了大量的研究，并取得良好的效果，但国内绝大部分烧结厂的烟气未经脱硝处理直接排放到大气中。随着环保要求的提高，降低烧结过程NOx排放已成为钢铁企业的一项长期战略目标。 在煤的解耦耦合燃烧降低NOx排放原理和烟气返回脱硝技术的基础上，结合烧结过程的特点，本文提出了解耦燃烧与烟气返回降低烧结过程NOx排放的新工艺。该工艺将煤热解产生的热解气引入到烧结过程，以添加剂改性后焦炭作为烧结燃料，同时将部分烟气返回到烧结过程，降低烧结过程NOx排放量。本文从热力学计算与实验研究两方面对该工艺进行了应用基础研究。 本论文在以下几个方面取得了创新性进展： (1) 为从理论上证实该新工艺的可行性，系统地进行了热解气组分以及焦炭还原NOx热力学计算。结果表明，热解气主要组分H2、CO、CH4和含氮化合物NH3、HCN还原性气体均能有效还原NOx。增大反应体系中O2浓度不利于NOx脱除。在焦炭燃烧过程中，燃烧的焦炭是良好的NOx还原剂，可将NOx还原为N2；在焦炭燃烧过程中，引入热解气组分H2、CO、CH4、NH3或HCN均可进一步提高NOx转化率。 (2) 为了研究烧结过程NOx还原作用机理，考察了热解气还原NOx均相反应中工艺参数对NOx脱除的影响。结果表明，在热解气还原NOx均相反应中，还原气氛下NOx可被完全还原为N2；NOx转化率随反应体系中O2浓度升高逐渐降低。采用Fe质反应器有利于提高NOx转化率。 (3) 在分段模拟烧结过程NOx还原反应的基础上，研究了烧结料层不同带层发生的脱硝反应与机理。结果表明，在烧结矿带，烧结矿对H2、CO和NH3还原NOx反应具有催化作用的组分为CaO、MgO和Fe2O3。在空气气氛下，烧结矿对热解气还原NOx反应的催化温度区间为300～650℃，NOx转化率为10～30%。以焦炭燃烧模拟燃烧带，在焦炭燃烧过程中引入4.0%的H2、CO，NOx排放分别降低9.4%和15.8%；引入0.15%的NH3可使NOx排放降低5.7%。以150ppmNOx模拟返回烟气，引入到上面三个过程，NOx排放量分别降低23.1%、18.0%和17.1%。 (4) 结合添加剂在改性焦炭燃烧过程的原位催化作用及烟气返回降低NOx排放机理，获得了焦炭改性与烟气返回工艺中NOx的排放规律。结果表明，K2CO3、Na2CO3、CaO、CaCl2、Fe3O4(38～47μm)和CeO2(38～47μm)负载量均为2.0%时，焦炭燃烧过程NOx排放量分别降低了26.54%、17.40%、8.58%、22.29%、15.05%和14.84%。以含150ppmNOx的气体模拟返回烟气，引入到2.0%K2CO3、2.0%CaO和2.0%Fe3O4和2.0%CeO2改性焦炭燃烧过程中，NOx排放量分别降低了36.7%、20.2%、19.8%和26.2%。 (5) 为实现解耦燃烧与烟气返回降低烧结NOx排放，考察了40kg级烧结放大实验NOx排放规律及脱硝工艺对烧结过程的影响。结果表明，以2.0%CaO、2.0%K2CO3和2.0%CeO2改性焦粉作为烧结燃料，NOx排放量分别降低13.5%、16.5%和18.8%。将含45ppmNOx的模拟烟气返回到2.0%CaO、2.0%K2CO3和2.0%CeO2改性焦粉为燃料的烧结过程中，NOx排放量分别降低32.56%、32.17%和36.10%，在上述烧结过程同时引入热解气组分H2、CO和NH3可将NOx排放降低40%以上。解耦燃烧与烟气返回降低烧结过程NOx排放工艺对烧结矿的机械强度和冶金还原性能影响较小，同时该工艺还具有经济性好，操作简单等优点，是一种有良好前景的烧结过程NOx减排新技术。
英文摘要	At present, the Chinese sintering process of iron ore annually emits 1.0×106 metric tons of NOx, which occupies around 10% of the total national emission of NOx. The sintering plants have had their hands full with two other pollution problems: sulfur dioxide and soot, and have achieved great success. Unfortunately, the flue gas was discharged into air without any NOx treatment. As emission control regulations get stricter, the NOx reduction in sintering process becomes an important environmental concern due to its role in the formation of photochemical smog and acid rain. Based on the principle of decoupling combustion of coal and the denitrification technology with recycling flue, and combined with the characteristics of iron ore sintering, a new process, named NOx reduction by coupling combustion with recycling flue gas, is proposed. The principles and technology of new process are introduced in detail in this paper. Pyrolysis gas and coke are produced during coking process, the pyrolysis are introduced into iron ore sintering, and the coke modified by additives are used as sintering fuel, and a part of flue gas is recycled into the sintering process, thereby fulfilling the NOx reduction in the sinter bed. Based on the calculation of NOx reduction by pyrolysis gas in thermodynamics and experimental investigation, the thesis aims to carry out the applied fundamental research on the above issues. In this thesis, the following achievements and progresses were summarized as follows: (1) To texify the feasibility of this new process, the reduction of NOx by pyrolysis gas components and coke was systematically calculated in thermodynamics. The results indicate that the major components, such as H2, CO, CH4, in pyrolysis gas and nitrogen compounds, such NH3 and HCN, can effectively convert NOx to N2. The enhancement of O2 concentration doesn’t favor the denitrification reactions. In coke combustion, the burning coke is better reducing agents for the conversion of NOx to N2, and the NOx conversion can be further increased by introducing the major components of pyrolysis gas, such as H2, CO, CH4, NH3 and HCN. (2) To realize the mechanism of NOx reduction in sintering, technical parameters in the homogeneous reaction of NOx reduction by pyrolysis gas were examined. The results show that NOx can be completely reduced to N2 under reducing atmosphere, while it would decrease with the increasing of O2 concentration. The iron reactor favors the enhancement of NOx conversion. (3) Based on the simulated segmental study of NOx reduction in sintering, the mechanism and reactions in the different layers of sinter ore were investigated. The results show that, the components of sinter ore possessing catalytic effect on NOx reduction are CaO, MgO and Fe2O3, the NOx conversion is 10~30% for 300~650℃. In the simulation investigation of combustion layer, the NOx emission can be reduced by 15.8%, 9.4% and 5.7% when the coke combustion with introducing 4.0%CO, 4.0% H2 and 0.15%NH3 respectively, the NOx emission can be reduced by 23.1%, 18.0% and 17.1% when the above processes are introduced by the recycled flue gas, simulated by air containing 150ppm NO. (4) Based on the in-situ catalytic effects of additives on NOx reduction in coke combustion and the mechanism of NOx reduction with recycling fule gas, the role of NOx emissions in NOx reduction by modified coke and recycling flue gas were obtained. NOx emission decreased by 26.54%, 17.40%, 8.58%, 15.05% and 14.84% when the loadings of K2CO3, Na2CO3, CaO, CaCl2, Fe3O4(38~47μm) and CeO2(38~47μm) were all 2.0%. The NOx emission could be reduced by 36.7%, 20.2%, 19.8% and 26.2% when the recycled flue gas, simulated by air containing 150ppm NO, was introduced into the combustion of coke loaded with 2.0%K2CO3, 2.0%CaO, 2.0%Fe3O4 and 2.0% CeO2. (5) To fulfilling NOx reduction by decoupling combustion and recycling flue gas in actual sintering process, the role of NOx emission in sintering pot test at 40kg level and the effect of denitrification process on sintering were investigated. The results show that NOx emission decrased by 13.5%, 16.5% and 18.8% when the coke loaded with 2.0% CaO, 2.0% K2CO3 and 2.0% CeO2 were used as sintering fuel, respectively. When the simulated flue gas containing 45ppm NO was recycled into the sintering process using 2.0% CaO, 2.0% K2CO3 and 2.0% CeO2 as fuel, NOx emission decreased by 32.56%, 32.17% and 36.10% respectively. If the pyrolysis gas was simultaneously introducing into sintering process, the NOx emission could be reduced by more than 40%. This new process had little side-effect on the mechanical strength and reducing performance of sintered ore, it also possessed such merits as ecological efficiency and simplification, therefore, it would be a proposing method of decreasing NOx emission in sintering process.
语种	中文
公开日期	2013-09-13
页码	217
内容类型	学位论文
源URL	[http://ir.ipe.ac.cn/handle/122111/1195]
专题	过程工程研究所_研究所（批量导入）
推荐引用方式 GB/T 7714	陈彦广. 解耦燃烧与烟气返回降低铁矿烧结过程NOx的基础研究[D]. 过程工程研究所. 中国科学院过程工程研究所. 2008.

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