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不同气氛下钠对煤粉着火特性影响的研究

http://www.doczj.com/doc/5384642703d8ce2f00662337.html - 1 - 中国科技论文在线不同气氛下钠对煤粉着火特性影响的研究

吴乐,乔瑜,王超,徐明厚

基金项目:高等学校博士学科点科研基金资助课题(20090142120056)

作者简介:吴乐,(1984-),男,博士生,主要研究方向:煤粉着火特性

通信联系人:乔瑜,(1977-),男,副教授,主要研究方向:. E-mail: yuqiao@http://www.doczj.com/doc/5384642703d8ce2f00662337.html

(华中科技大学煤燃烧国家重点实验室,武汉 430074) 摘要:煤的氧/燃料燃烧方式是目前最容易实现大规模CO 2富集和减排的技术,首先利用逐5 步萃取研究了LY 褐煤中不同形态钠的分布情况,利用金属网反应器研究了LY 褐煤中不同形态钠在空气和O 2/CO 2气氛下对煤粉着火的影响。研究发现LY 褐煤中内在钠以水溶态和醋酸铵溶态为主,二者共占煤中总钠的88.19%,酸溶态和不可溶态含量较小。煤粉着火的试验结果表明,O 2/CO 2气氛下水洗后煤的着火温度降低约30℃,经醋酸铵和酸洗后煤粉着火温度明显升高,与原煤相比大约分别升高了50和100℃,对各样品进行了反应动力学分析,结10 果表明低温段水洗后煤样的表观活化能比原煤低,而经醋酸铵和酸洗后样品的表观活化能均升高,反应动力学分析与着火试验结果一致。

关键词:O 2/CO 2气氛;着火特性;钠;反应性

中图分类号:TQ534

15

Effect of sodium on pulverized coal ignition temperature

under different atmosphere

WU Le, QIAO Yu, WANG Chao, XU Minghou

(State key laboratory of coal combustion,Huazhong University of Science and Technology, WuHan 430074)

20 Abstract: In this paper LY brown coal was first sequential extracted to classify the form of Na compounds. Experiments were performed in a wire-mesh reactor to determine the effects of indigenous sodium on ignition behaviour of coal in air and O 2/CO 2 conditions. Water-soluble and ammonium acetate-soluble Na are the mainly form in coal represents about 88.19% of the Na present in the coal, acid-soluble Na and insoluble Na represents a small part of the Na present in 25 the coal. Compared with the average particle ignition temperatures of raw coal, those of water-washed coal sample indicated minimum and approximately decreased 30℃ both in air and 21% O 2/79% CO 2 atmosphere, those of ammonium acetate-washed and acid-washed coal samples increased about 50℃and 100℃ respectively. Coal reactivity measurements were also carried out, compared to raw coal the activation energy of water washed LY brown coal decreased, and after 30 the raw coal was washed by ammonium acetate and acid the activation energy increased evidently. As the apparent activation energy higher, the higher the energy needed for reaction, the reaction is more difficult, so the reaction kinetic analysis well agree with the ignition temperature results . Keywords:O 2/CO 2 atmosphere; ignition characteristics; sodium; reactiv
ity

20 Abstract: In this paper LY brown coal was first sequential extracted to classify the form of Na compounds. Experiments were performed in a wire-mesh reactor to determine the effects of indigenous sodium on ignition behaviour of coal in air and O 2/CO 2 conditions. Water-soluble and ammonium acetate-soluble Na are the mainly form in coal represents about 88.19% of the Na present in the coal, acid-soluble Na and insoluble Na represents a small part of the Na present in 25 the coal. Compared with the average particle ignition temperatures of raw coal, those of water-washed coal sample indicated minimum and approximately decreased 30℃ both in air and 21% O 2/79% CO 2 atmosphere, those of ammonium acetate-washed and acid-washed coal samples increased about 50℃and 100℃ respectively. Coal reactivity measurements were also carried out, compared to raw coal the activation energy of water washed LY brown coal decreased, and after 30 the raw coal was washed by ammonium acetate and acid the activation energy increased evidently. As the apparent activation energy higher, the higher the energy needed for reaction, the reaction is more difficult, so the reaction kinetic analysis well agree with the ignition temperature results . Keywords:O 2/CO 2 atmosphere; ignition characteristics; sodium; reactivity

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0 引言

O 2/CO 2燃烧技术是一种被认为是可以分离回收CO 2的新型燃烧技术,该技术排烟中CO 2浓度高达95%以上,可以在油气田回注CO 2既可用来提高油田和煤层气的采收率,将CO 2永久地封存隔离在地下岩层中,可有效减少温室气体的排放。已有的研究结果表明其燃烧机理与常规空气气氛燃烧有明显的不同,研究发现在O 2/CO 2气氛下火焰的着火点模糊和不稳

40 定,通过减少循环烟气量、提高二次风中的氧含量等措施可以改善燃烧特性O 2/CO 2气氛比相同氧含量的O 2/N 2气氛下的火焰温度低[1-7]。与烟煤相比褐煤中碱金属-碱土金属元素(AAEM )在褐煤利用中是必须要考虑的重要因素,研究表明AAEM 尤其是钠元素被认为可以改善煤粉热解、气化、着火特性和燃尽特性的催化剂,许多学者在空气气氛下研究了其

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