洁净煤技术

2021, v.27;No.132(02) 246-252

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等速升温流态化下CaO/生物质焦的SO_2/NO联合脱除特性
Characteristics of simultaneous SO_2/NO removal by CaO/bio-char under fluidization at constant heating rate

张春晓;李英杰;
ZHANG Chunxiao;LI Yingjie;School of Energy and Power Engineering,Shandong University;

摘要(Abstract):

燃煤锅炉污染物超低排放标准对电厂脱硫和脱硝系统提出了更高的要求。CaO作为脱硫剂可以实现循环流化床锅炉烟气中SO_2的高效脱除,焦炭作为还原剂直接还原NO,同时CaO的存在对焦炭还原NO起催化作用,可以实现燃煤烟气中SO_2/NO的联合脱除。为了探究连续温度变化对CaO/生物质焦联合脱硫脱硝性能的影响,在钙循环捕集CO_2技术背景下,研究了等速升温流态化下CaO/生物质焦的SO_2/NO联合脱除特性。探究了烟气中O_2和CO_2对CaO/椰壳焦脱除SO_2/NO的影响。结果表明,O_2通过对椰壳焦表面碳原子的活化作用降低了异相还原NO温度,在300~950℃等速升温过程中CaO/椰壳焦的NO脱除效率逐渐增加,780℃以上能实现100%脱硝。O_2也提高了CaO/椰壳焦的脱硫效率。CO_2与CaO的碳酸化反应以及与椰壳焦的气化反应对同时脱除SO_2/NO有明显抑制作用。O_2和CO_2共同作用下,在500~800℃内CaO/椰壳焦的脱硝效率随温度升高而增加,脱硫效率先降低后升高。NO促进了CaO/椰壳焦脱除SO_2,而SO_2对脱硝有抑制作用。800℃时CaO/椰壳焦同时脱除SO_2和NO的效率分别为97.7%和93.9%。
The desulfurization and denitrification systems face sever challenges due to the ultra-low emission rules of coal-fired boilers.CaO-based sorbents can effectively remove SO_2 from flue gas of circulating fluidized bed boilers. Char can be used as a reducing agent to reduce NO directly,and CaO plays a catalytic role in the reduction reaction of NO by char. which can realize the simultaneous SO_2 and NO removal in flue gas. Based on calcium looping technology for CO_2 capture,the simultaneous SO_2/NO removal performance of CaO/bio-char was investigated under fluidization at constant heating rate in this study to explain the effect of continuous temperature change on the simultaneous SO_2 and NO removal by CaO/bio-char. The influences of O_2 and CO_2 in flue gas on the simultaneous SO_2/NO removal performance of CaO/coconut shell char were discussed. The results indicate that O_2 can reduce the temperature of heterogeneous reduction of NO by activating carbon atoms on the surface of coconut shell char. The NO removal efficiency increases gradually with constant rate heating from 300 ℃ to 950 ℃,reaching 100% at above 780 ℃ . The SO_2 removal efficiency of CaO/coconut shell char is also promoted by O_2. The simultaneous SO_2/NO removal is inhibited by the carbonation reaction between CaO and CO_2 as well as CO_2 gasification of coconut shell char. In the presence of both O_2 and CO_2,the NO removal efficiency increases as temperature increases from 500 ℃ to 800 ℃,while the SO_2 removal efficiency firstly decreases and then increases. SO_2 inhibits the NO removal of CaO/coconut shell char,while NO can promote the SO_2 removal performance. The simultaneous SO_2 and NO removal efficiencies of CaO/coconut shell char at 800 ℃ are 97.7% and94%,respectively.

关键词(KeyWords): CaO;生物质焦;SO_2/NO联合脱除;流态化;等速升温;钙循环
CaO;bio-char;simultaneous SO_2/NO removal;fluidization;constant heating rate;calcium looping

Abstract:

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基金项目(Foundation): 国家自然科学基金资助项目(51876105)

作者(Author): 张春晓;李英杰;
ZHANG Chunxiao;LI Yingjie;School of Energy and Power Engineering,Shandong University;

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DOI: 10.13226/j.issn.1006-6772.CCUS20072801

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