摘要
燃煤释放的大量SO_(2)气体给人类的生活和生产活动带来极大的危害。与此同时,燃煤排出的固体废弃物粉煤灰大量堆积也易造成粉尘污染。降低燃煤SO_(2)排放和消减粉煤灰已成为主要研究课题。粉煤灰的主要成分为SiO_(2),Al_(2)O_(3),Fe_(2)O_(3)和CaO,其中Fe_(2)O_(3)和CaO对烟气中的SO_(2)具有一定脱除作用。CaO烟气脱硫效率高,但钙利用率较低,可以通过合适的改性方法提高其利用率。基于以废治废原则,通过湿式磁选将粉煤灰中的铁氧化物富集,获得高铁灰,将高铁灰与氧化钙水合制备钙基脱硫剂,并在固定床评价系统上进行SO_(2)脱除试验,结合XRD,BET和FTIR等揭示高铁灰对钙基脱硫剂脱除SO_(2)行为的影响。结果显示,高铁灰钙基脱硫剂具有较好的脱硫性能,穿透时间和硫容分别为26 min和14.87 mg/g。其原因是在钙基脱硫剂中添加高铁灰后,可增加钙基脱硫剂内水化物和铁氧化物等活性组分,脱硫反应活性中心由CaO颗粒转移至Fe_(2)O_(3)颗粒;Fe_(2)O_(3)具备储氧释氧功能,同时附着于CaO颗粒表面,使高铁灰脱硫剂表面具有优良的孔隙结构,易于SO_(2)气体穿过孔隙进入脱硫剂内部,延长脱硫反应时间,进而提升脱硫剂的脱硫能力;另一方面,Fe_(2)O_(3)的存在促进了被吸附在脱硫剂表面的SO_(2)转化为SO3,最终脱除的SO_(2)以SO^(2-)_(4)形式存在。动力学分析结果显示化学吸附脱除在吸附脱硫中起主导作用,化学吸附动力学遵循准二级动力学模型,高铁灰有助于增强钙基脱硫剂对SO_(2)的化学脱除能力。
A large amount of SO_(2)gas released by coal-burning brings great harm to human life and production activities.Meanwhile,the accumulation of solid waste fly ash discharged by coal-burning can cause dust pollution.Reducing SO_(2)emissions and fly ash from coal-burning have long been the main research topics for many researchers.The main components in fly ash are SiO_(2),Al_(2)O_(3),Fe_(2)O_(3),and CaO,among which Fe_(2)O_(3)and CaO have a certain SO_(2)removal activity.The desulfurization efficiency of CaO is higher,but the calcium utilization rate is lower.Its utilization rate may be improved by appropriate modification methods.In this paper,the rich iron oxides in fly ash were extracted by wet magnetic separation,thus the high-content iron ash was obtained.Calcium oxide was modified by hydration with the high-content iron ash and the calcium-based desulfurizer was obtained.The SO_(2)removal experiments were carried out on the fixed bed evaluation system.Combined with the results of XRD,BET,and FTIR,the influence of high-content iron ash on the SO_(2)removal performance of calcium-based desulfurizer is revealed.The results show that calcium-based desulfurizer modified by the high-content iron ash has good desulfurization ability,and the breakthrough time and sulfur capacity are 26 min and 14.87 mg/g,respectively.The hydration modification of calcium oxide and high-content iron ash can increase hydrates and the active components of iron oxides,and the active center of the desulfurization reaction is transferred from CaO to Fe_(2)O_(3)particles.Fe_(2)O_(3)has the function of oxygen storage and release,and is attached to the surface of CaO particles,resulting in excellent pore structure on the surface of desulfurizer.It is easy for SO_(2)to enter the desulfurizer through the pores,thus,the desulfurization reaction time is prolonged and the desulfurization capacity of desulfurizer is improved.On the other hand,Fe_(2)O_(3)can promote the conversion of SO_(2)adsorbed on the desulfurizer surface into SO3,and the final removed SO_(2)exists in the form of SO^(2-)_(4).The results of the kinetic analysis show that the chemical adsorption removal plays a leading role in adsorption desulfurization,and the chemical adsorption kinetics follows the quasi second-order kinetic model.The high-content iron ash may enhance the chemical removal ability of calcium-based desulfurizer for SO_(2).
作者
郑仙荣
梁云波
谭煜幺
ZHENG Xianrong;LIANG Yunbo;TAN Yuyao(College of Electrical and Power Engineering,Taiyuan University of Technology,Taiyuan 030024,China)
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2022年第S01期350-355,共6页
Journal of China Coal Society
基金
山西省自然科学基金资助项目(201901D111121)
关键词
高铁灰
钙基脱硫剂
水合改性
脱硫
化学吸附
high-content iron ash
hydration modification
calcium-based desulfurizer
desulfurization
chemical adsorption
