Mercury removal performance of bromine-modified coconut shell activated carbon in real flue gas

doi:10.16085/j.issn.1000-6613.2018-2086

Abstract

Abstract:

The bromine-modified coconut shell activated carbon (YAC-Br) for mercury removal adsorbent was prepared by using the coconut shell activated carbon (YAC) as raw material and impregnating with NH₄Br solution. The mercury removal experiments of YAC and YAC-Br were carried out in a fixed bed. The effects of initial mercury (Hg⁰) concentration on the mercury removal performance of YAC-Br were studied. The principle of mercury removal from YAC-Br was analyzed, combined with characterization methods such as BET, SEM and XRF. Activated carbon injection (ACI) experiments were carried out on a 0.3MW coal-fired circulating fluidized bed boiler to study the adsorption effect of YAC-Br on mercury in real flue gas. The results showed that the modification process has no damage on the original pore structure and pore volume of YAC, but it makes the surface smoother. After chemical modification, the Br-loading capacity on the activated carbon surface increases and becomes the main active adsorption site of Hg⁰. The results of the fixed bed experiments showed that the initial mercury adsorption efficiency and unit cumulative mercury adsorption capacity of YAC-Br increases by 6.02 times and 21.8 times, respectively. The adsorption efficiency decreases with the increase of mercury initial concentration. The results of the 0.3MW circulating fluidized bed coal combustion experiments showed that YAC-Br has good adsorption to elemental mercury and oxidized mercury. The mercury removal efficiency increases with the increase of the adsorbent injection amount. When the injection amount was 0.7kg/h, the mercury removal efficiency reached 76.38%.

Key words: ammonium bromide, modification, coconut shell activated carbon, CFB, mercury adsorption, injecting mercury removal

摘要：

以椰壳活性炭（YAC）为原料，通过NH₄Br溶液浸渍改性，制备了溴素改性椰壳活性炭脱汞吸附剂（YAC-Br）。在固定床实验台上开展了YAC和YAC-Br的汞脱除实验，主要研究了入口汞（Hg⁰）浓度对YAC-Br脱汞性能的影响，并结合BET、SEM、XRF等表征手段分析了YAC-Br的脱汞原理。在0.3MW燃煤循环流化床锅炉上对YAC-Br进行了烟气管道喷射吸附剂脱汞（ACI）实验，验证了其在实际燃煤烟气中对汞的脱除效果。结果表明：改性过程不会破坏椰壳活性炭原有的孔隙结构和微孔容积，而会使活性炭表面更加平整；化学改性后活性炭表面Br负载量提高，成为Hg⁰的主要活性吸附位。固定床实验结果说明：改性后椰壳活性炭的初始汞吸附效率和单位累积汞吸附量分别提高了6.02倍和21.8倍，吸附效率随汞浓度增大而降低。0.3MW燃煤循环流化床实验结果表明：改性后椰壳活性炭对元素汞和氧化汞均有很好的脱除作用，脱汞效率随着吸附剂喷射量的增加而增加，当喷射量为0.7kg/h时，脱汞效率可达到76.38%。

关键词: 溴化铵, 改性, 椰壳活性炭, 循环流化床, 汞吸附, 喷射脱汞

CLC Number:

X 511

Fan ZHANG,Yufeng DUAN,Shuai LIU,Jincheng LU,Shaojun REN,Hongqi WEI,Jun WANG. Mercury removal performance of bromine-modified coconut shell activated carbon in real flue gas[J]. Chemical Industry and Engineering Progress, 2019, 38(08): 3881-3888.

张帆,段钰锋,柳帅,卢锦程,任少君,韦红旗,王军. 溴元素改性椰壳活性炭对实际燃煤烟气的脱汞性能[J]. 化工进展, 2019, 38(08): 3881-3888.

Figures/Tables 13

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序号	喷射量/kg·h^-1	烟气温度/℃	停留时间/s	氨氮比	SO₂/μL·L^-1	NO/μL·L^-1	O₂体积分数/%
1	0.3	170	3	0.8	678	335	9
2	0.5	170	3	0.8	633	311	7.8
3	0.7	170	3	0.8	719	351	10.07

序号	喷射量/kg·h^-1	烟气温度/℃	停留时间/s	氨氮比	SO₂/μL·L^-1	NO/μL·L^-1	O₂体积分数/%
1	0.3	170	3	0.8	678	335	9
2	0.5	170	3	0.8	633	311	7.8
3	0.7	170	3	0.8	719	351	10.07

样品	BET比表面积/m²·g^-1	微孔容积/cm³·g^-1	总孔容积/cm³·g^-1	微孔率/%	平均孔径/nm
YAC	761	0.30	0.39	75.2	2.07
YAC-Br	769	0.31	0.40	76.1	2.09

样品	BET比表面积/m²·g^-1	微孔容积/cm³·g^-1	总孔容积/cm³·g^-1	微孔率/%	平均孔径/nm
YAC	761	0.30	0.39	75.2	2.07
YAC-Br	769	0.31	0.40	76.1	2.09

样品	C	O	Si	Na	Mg	Al	Cl	Br
YAC	73.19	21.73	1.84	0.50	0.29	0.42	0.29	—
YAC-Br	75.79	20.19	1.20	0.23	0.23	0.46	0.22	0.011