All Title Author
Keywords Abstract

-  2018 

生物质气化飞灰的吸附汞性能

DOI: 10.13360/j.issn.2096-1359.2018.06.018

Keywords: 生物质气化, 飞灰, 汞吸附, 吸附性能, 吸附材料
biomass gasification
, fly ash, mercury adsorption, adsorption property, adsorbing materials

Full-Text   Cite this paper   Add to My Lib

Abstract:

为开发高效廉价的新型吸附材料,利用生物质流化床气化副产物――飞灰作为燃煤烟气中汞的吸附材料。以稻秆为原料,在小型流化床试验台上进行气化试验,制得不同工况下的飞灰样品。对飞灰进行NH4Br溶液浸渍改性,采用工业分析、氮气吸附/脱附、扫描电子显微镜-X射线能谱仪(SEM-EDS)、X射线荧光光谱仪(XRF)等分析方法研究飞灰改性前后的理化性质及微观形貌。在固定床气态汞吸附试验台上进行脱汞试验,分析制备工况、吸附温度对飞灰吸附汞效率的影响。结果表明,NH4Br溶液浸渍改性大幅提高了飞灰的比表面积及孔容,并促使其表面有效负载了活性元素溴,从而提升了飞灰的汞吸附性能。同时,升高气化温度有利于改善飞灰孔隙结构,700 ℃气化温度下的飞灰经改性后吸附效率和单位吸附量明显高于600 ℃气化温度下的飞灰样品。而当量比的增加对飞灰的孔隙结构产生了负面影响,不利于活性元素溴的负载,单位吸附量随之减小。吸附效率随吸附温度的增加呈先上升后下降的趋势,当吸附温度为120 ℃时,能达到较好的物理吸附与化学吸附之间的平衡。700 ℃气化温度及0.10当量比下的飞灰经NH4Br溶液改性后吸附效率最高,可达90%以上,单位吸附量为42.89 μg/g,且对应工况的气化气热值最高,可在较好的生产系统性下同时获得高热值燃气和高吸附性能的气化飞灰。
In purpose to develop efficient and inexpensive adsorbing materials, gasification fly ashes, the by-products of biomass gasification in fluidized beds, were used as sorbents for capturing mercury in the coal-fired flue gas. Fly ashes from rice straw gasification in a bench-scale fluidized bed were produced under different operating conditions. Obtained fly ashes were treated by impregnation method with NH4Br solution. The original and modified fly ashes were then characterized by proximate analysis, nitrogen adsorption/desorption, SEM-EDS and XRF for their physicochemical properties and microscopic appearances. The effects of preparation condition and adsorbent temperature on the adsorption efficiency of the fly ashes to remove mercury were performed on a fixed-bed reactor. The experimental results showed that the impregnation treatment with NH4Br solution could increase the specific area and pore volume of the fly ashes and load the active element Br to the surface of the samples, which enhanced both the physical and chemical adsorption capability of the fly ashes. In addition, the increase of gasification temperature played a positive role in improving the pore structure of fly ashes by effectively loading more active element. The adsorption efficiency and quantity of the modified fly ash from gasification at 700 ℃ were apparently higher than those of the sample from gasification at 600 ℃. However, increasing equivalence ratio had the opposite effects on the pore structure of fly ashes and the load of the active element, leading to a lower adsorption quantity. At the same time, the adsorbent temperature had a significant influence on the adsorption efficiency in the process of the mercury removal. The adsorption efficiency increased firstly then descended latter with the increase of adsorbent temperature, and a good balance between physical absorption and chemical adsorption could be achieved when the adsorbent temperature was 120 ℃. To conclude, the modified fly ash produced from

Full-Text

comments powered by Disqus

Contact Us

service@oalib.com

QQ:3279437679

微信:OALib Journal