选择性脱除三氧化硫技术研究
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摘要
目前常用于控制SO_3的吸收剂在脱除SO_3的同时也会脱除SO_2,导致吸收剂用量大、成本高。针对该问题,考察了NaHSO_3、Na_2SO_3等7种常用吸收剂对SO_3的脱除率和选择性,筛选出可以高效选择性脱除SO_3的吸收剂NaHSO_3,并研究了烟气工况对NaHSO_3脱除SO_3效率和选择性的影响。结果表明:吸收剂NaHSO_3在温度为300℃,空速为60000 h~(-1)的烟气工况下经过1 h的连续反应后,对SO_3的脱除率维持在86.2%左右,其选择性为100%;通过升高温度、增大空速和增加入口SO_3浓度等方式,相同时间内SO_3的累积脱除量均有所提高。用颗粒内扩散模型和Elovich动力学模型对不同烟气工况下的实验结果进行拟合,结果表明颗粒内扩散不是控制脱除过程的唯一因素,而化学吸附可能是NaHSO_3脱除SO_3的主要途径。
Since the current common absorbents for SO_3 controlling will also remove SO_2 while removing SO_3, which results in the large consumption of absorbents and high cost, therefore, in order to solve this problem, the removal efficiency and selectivity of SO_3 by seven absorbents including NaHSO_3, Na_2SO_3, etc., were investigated and NaHSO_3 was screened out as the optimal one. The effect of flue gas conditions on the removal efficiency and selectivity of SO_3 was also studied with NaHSO_3. The results showed that after a continuous reaction for 1 h under 300 ℃ at a space velocity of 60000 h~(-1), the SO_3 removal efficiency by NaHSO_3 maintained at about 86.2% with selectivity of 100%; moreover, with the increase of temperature, space velocity, and SO_3 concentration at entrance, the cumulative removal amount of SO_3 increased within the same time. The intra-particle diffusion model and the Elovich kinetic model were used to fit the experimental results under different flue gas conditions, and the results showed that intra-particle diffusion was not the only factor to control the removal process, while chemical adsorption might be the main way for NaHSO_3 to remove SO_3.
Since the current common absorbents for SO_3 controlling will also remove SO_2 while removing SO_3, which results in the large consumption of absorbents and high cost, therefore, in order to solve this problem, the removal efficiency and selectivity of SO_3 by seven absorbents including NaHSO_3, Na_2SO_3, etc., were investigated and NaHSO_3 was screened out as the optimal one. The effect of flue gas conditions on the removal efficiency and selectivity of SO_3 was also studied with NaHSO_3. The results showed that after a continuous reaction for 1 h under 300 ℃ at a space velocity of 60000 h~(-1), the SO_3 removal efficiency by NaHSO_3 maintained at about 86.2% with selectivity of 100%; moreover, with the increase of temperature, space velocity, and SO_3 concentration at entrance, the cumulative removal amount of SO_3 increased within the same time. The intra-particle diffusion model and the Elovich kinetic model were used to fit the experimental results under different flue gas conditions, and the results showed that intra-particle diffusion was not the only factor to control the removal process, while chemical adsorption might be the main way for NaHSO_3 to remove SO_3.
引文
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[2] 刘宇,单广波,闫松,等. 燃煤锅炉烟气中SO3的生成、危害及控制技术研究进展[J]. 环境工程,2016,34(12):93-97.
[3] 罗汉成,潘卫国,丁红蕾,等. 燃煤锅炉烟气中SO3的产生机理及其控制技术[J]. 锅炉技术,2015,46(6):69-72.
[4] 唐昊,陆强,杨江毅,等. 废弃SCR催化剂的循环再利用及表征分析研究[J]. 燃料化学学报,2018,46(2):233-242.
[5] 竹涛,张书庆,郭娜. 火电行业SO3控制技术研究进展[J]. 环境工程,2018,36(2):109-112,130.
[6] Kocaefe D,Karman D,Steward F R. Comparison of the sulfation rates of calcium, magnesium and zinc oxides with SO2 and SO3[J]. The Canadian Journal of Chemical Engineering,1985,63(6):971-977.
[7] 高智溥,胡冬,张志刚,等. 碱性吸附剂脱除SO3技术在大型燃煤机组中的应用[J]. 中国电力,2017,50(7):102-108.
[8] 刘含笑,姚宇平,郦建国,等. 燃煤电厂烟气中SO3生成、治理及测试技术研究[J]. 中国电力,2015,48(9):152-156.
[9] 蔡培,赵洋. 脱除三氧化硫解决空预器堵塞优化方案研究[J]. 电力科技与环保,2016,32(3):42-43.
[10] 蒋海涛,蔡兴飞,付玉玲,等. 燃煤电厂SO3形成、危害及控制技术[J]. 发电设备,2013,27(5):366-368.
[11] 王宏亮,薛建明,许月阳,等. 燃煤电站锅炉烟气中SO3的生成及控制[J]. 电力科技与环保,2014,30(5):17-20.
[12] 李小龙,段玖祥,李军状,等. 燃煤电厂烟气中SO3控制技术及测试方法探讨[J]. 环境工程,2017,35(5):98-102.
[13] 杨雪梅,林玉,白正伟. 钍试剂滴定法测定硫化催化裂化烟气中二氧化硫和三氧化硫的含量[J]. 理化检验(化学分册),2015,51(7):893-896.
[14] 陈松涛. 富氧燃烧条件下SO3催化生成及吸附脱除的研究[D]. 武汉:华中科技大学,2015.
[15] 刘平,陶政修. 醋酸钙溶液吸收二氧化硫烟气的试验研究[J]. 环境科学导刊,2007(1):4-6.
[16] 周强,段钰锋,冒咏秋,等. 活性炭汞吸附动力学及吸附机制研究[J]. 中国电机工程学报,2013,33(29):10-17.
[17] 蔡梦琦. 活性炭吸附烟气中CO2的研究[D]. 北京:北京化工大学,2015.