亚临界水条件下煤中汞的脱除

运用半连续反应装置对山西吴家坪煤中汞在亚临界水中的脱除规律进行了研究。考察了反应温度为290 ℃、320 ℃ 、350 ℃、 380 ℃，反应压力为5 MPa、10 MPa、15 MPa,萃取时间为10 min、30 min、60 min、100 min时对汞脱除率的影响。结果表明，在290 ℃～380 ℃，随着温度升高，汞脱除率明显增加；在5 MPa～15 MPa，压力越大，汞的脱除率也越大；在10 min～100 min，随着萃取时间的延长，汞脱除率增加；在380 ℃, 15 MPa, 1 h，汞的脱除率最大可达96％以上。     

Study of mercury adsorption by selected Chinese coal fly ashes

Recent research has shown that fly ash produced in coal-fired power plants can play an important role in mercury removal. The aim of this study was to establish the relationships between fly ashes produced from different coals and boiler types and their mercury adsorption capacity. In order to achieve this objective, Brunauer–Emmett–Teller surface area, scanning electron microscopy, thermogravimetric analysis, and a mercury measurement system were employed to characterize the samples. The results show that the average pore size of fly ash is the single most important factor with residual carbon content fulfilling a secondary role in the capture of elemental mercury. The addition of HBr with fly ash can remarkably enhance the mercury adsorption performance of fly ash.     

热解气氛对晋城煤中汞析出的影响

将程序升温热解反应系统和元素Hg在线检测系统耦合,在200℃～1 200℃,研究了晋城煤在N2、CO2和H2气氛下热解过程中Hg的释放特性,特别是元素Hg在释放总Hg中的分布.在N2、CO2、H2气氛下,Hg的释放均起始于200℃左右,至1 200℃时释放率达95%以上,且Hg的释放率均大于挥发分产率.释放汞的主要形式是元素汞,可说明炭在汞释放中起还原作用;N2气氛下Hg释放总量中元素Hg占97%,CO2和H2气氛下Hg释放总量中元素Hg占73%,说明H2和CO2可将部分元素汞转化为其他价态的汞.     

煤燃烧中的汞转化模型和数值模拟

煤燃烧中汞高温下以单质形式存在,在烟道里随着温度降低,单质汞部分转化为二价汞,并再有部分汞吸附在灰渣中而被除尘设备收集,减少了环境的汞污染。针对煤燃烧汞的转化过程,用动力学模型和吸附模型结合来描述汞的转化机理,并用数值模拟方法研究了煤中氯的质量分数、烟气降温速率、烟气停留时间等因素的影响。结果表明,煤中氯的质量分数为0.08×10－6以上,烟气停留6s以上时,可以使汞的吸附率达到40％以上。对汞转化模型,用一组580MJ/h燃烧系统150℃烟道温度数据进行了验证,结果证实试验数据与计算数据能较好相符,模型具有一定的可靠性。     

晋城煤中汞的热稳定性与赋存形态的研究

利用程序升温热解反应器─元素汞在线检测系统联用装置,研究了晋城煤中汞的热稳定性以及与热稳定性相关的晋城煤中汞的赋存形态。研究表明,煤中大部分汞与煤中无机矿物质伴/共生,少部分与煤中有机质伴/共生。其中,在200℃~300℃和900℃~1200℃释放的汞与煤中无机矿物质伴/共生,在300℃~600℃释放的汞部分与无机矿物质伴/共生,部分与煤中有机质伴/共生。     

高钠煤水热脱钠处理及其对燃烧特性的影响

以五彩湾高钠煤为研究对象,根据煤中钠的赋存形态,分别研究了不同条件下水洗和水热处理两种方式对碱金属的脱除效果,同时考察了水热处理对煤燃烧特性的影响。结果表明,五彩湾煤中钠主要以水溶性钠盐存在;单纯水洗对Na的脱除效果不理想,并且工艺耗时长、耗水量大;水热处理脱钠效率高,钠脱除率高达90.5%,处理后的煤灰中Na2O含量降至0.7%,属于低钠煤范围;水热处理后煤样的燃烧速率曲线移向低温区,燃烧特性优于原煤。     

Preparation of activated carbon for mercury capture from chicken waste and coal

Chicken waste and chicken waste blended samples with selected high sulfur coal were used as raw materials for activated carbon preparation. Raw materials were subjected to the preparation procedures of carbonization in a nitrogen atmosphere and activation in a steam atmosphere. The basic properties of the raw materials, chars and activated carbons were investigated by components analysis, surface porosity and thermogravimetric analysis. Two activated carbon samples were selected for elemental mercury capture tests in a lab-scale drop tube reactor with air flow.

The current results show that chicken waste is not a suitable raw material for activated carbon production due to its higher contents of volatile matter and ash. Coal can be used as a carbon carrier for improving the carbon content of products. A low-cost activated carbon was prepared by a co-process of chicken waste and coal, and examining the high capture efficiency for elemental mercury. It suggests that the coal provides a carbon carrier or trap for some active species, such as chlorine released from the chicken waste. These active species would likely provide or create the adsorptive sites on the surface of activated carbon for elemental mercury.     

Preparation of activated carbon for mercury capture from chicken waste and coal

Chicken waste and chicken waste blended samples with selected high sulfur coal were used as raw materials for activated carbon preparation. Raw materials were subjected to the preparation procedures of carbonization in a nitrogen atmosphere and activation in a steam atmosphere. The basic properties of the raw materials, chars and activated carbons were investigated by components analysis, surface porosity and thermogravimetric analysis. Two activated carbon samples were selected for elemental mercury capture tests in a lab-scale drop tube reactor with air flow.The current results show that chicken waste is not a suitable raw material for activated carbon production due to its higher contents of volatile matter and ash. Coal can be used as a carbon carrier for improving the carbon content of products. A low-cost activated carbon was prepared by a co-process of chicken waste and coal, and examining the high capture efficiency for elemental mercury. It suggests that the coal provides a carbon carrier or trap for some active species, such as chlorine released from the chicken waste. These active species would likely provide or create the adsorptive sites on the surface of activated carbon for elemental mercury.     

Bioabatement to remove inhibitors from biomass-derived sugar hydrolysates

Bioabatement is a potential method to remove inhibitory compounds from lignocellulose hydrolysates that could be incorporated into a scheme for fermentation of ethanol from cellulose. Coniochaeta ligniaria NRRL30616, an Ascomycete that metabolizes furfural and 5-hydroxymethylfurfural, is a unique strain that may be useful for detoxifying biomass sugars. NRRL30616 and 23 related fungal strains were screened for the ability to metabolize furans and grow in dilute-acid hydrolysate of corn stover. NRRL30616 was the best strain for removal of inhibitors from hydrolysate, and abatement of hydrolysate by inoculation with the strain allowed subsequent yeast fermentation of cellulose to ethanol. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.     

Nanofiltration treatment of aqueous solutions to remove triazine herbicides

Nanofiltration treatment of aqueous solutions to remove triazine herbicides (terbumetone, desmetrine, atrazine) with an OPMN-P membrane was studied. The effect of the molecular mass of herbicides, working pressure, and extent of permeate removal on the retention of solutes was analyzed.     

Sorption purification of saturated hydrocarbons to remove aromatic compounds

Prospects for use of microscopic amounts of fullerenes as a modifying additive for improving the absorption capacity of conventional adsorbents in both static and dynamic conditions of purification of saturated hydrocarbons to remove aromatic compounds were examined.     

Treatment of wastewater to remove ammonium ions by precipitation

The process of wastewater treatment to remove ammonium ions by precipitation in the form of ammonium magnesium phosphate was studied. The fundamental aspects of the chemical precipitation process were examined. The effect of various factors on the efficiency of wastewater treatment was experimentally analyzed.     

氧弹分解-原子荧光法测定煤中汞的研究进展

介绍氧弹分解-原子荧光法测定煤中汞含量的研究进展。影响该方法主要因素为称样量、氧气浓度、吸收剂、还原剂、煤种以及灰分含量。分别综述了各个因素对该方法的影响,可为相关标准的制定提供参考。该方法能够简单、经济、快速地测定煤中汞的含量,但是目前学者们对于该方法的相关研究还存在分歧,需要进一步的研究验证;同时,还需要注意以下几个研究方向:吸收剂和还原剂的选择对汞回收率的影响;吸收剂在密闭氧弹中对汞的回收率及吸收时间的研究;氧弹废气中汞含量的测定;煤种和灰分含量对汞含量测定的影响。     

CaCl2添加对热解煤中汞析出规律影响的实验研究

在程序升温热解反应装置上,研究了低氯煤中添加不同氯含量（质量分数0.1%、0.3%、0.5%）的CaCl₂对煤热解过程中汞析出规律的影响。实验结果表明,温度是影响汞析出的关键因素;随着氯添加量的增加,Hg²⁺析出比例呈上升趋势,且汞的最佳析出温度降低,汞的释放率也有所降低;随着热解气氛中O₂比例的增加,Hg²⁺比例也略有增加;较高的升温速率能加快汞的释放,也能提高Hg²⁺的比例。低氯煤中添加氯化钙能够强化单质汞的氧化。     

膨润土-壳聚糖及其改性吸附剂脱除燃烧烟气中Hg0的性能研究

应用VM3000在线测汞仪作为检测手段,在固定床实验台架上,以改性膨润土 壳聚糖为吸附剂进行脱汞(Hg⁰)实验研究。采用N₂吸附/脱附、扫描电镜(SEM)和傅里叶变换红外光谱(FT-IR)等分析仪对吸附剂进行表征。分析发现改性后吸附剂的孔隙和比表面积降低;碘离子进入了膨润土的内部,碘、硫酸和壳聚糖中的氨基发生了化学反应。脱汞实验表明,负载壳聚糖的膨润土吸附剂表现出较膨润土差的脱汞效果,证明膨润土负载壳聚糖脱除气态中单质汞的机理和液相中二价汞的机理不同。经碘改性后,各吸附剂均可不同程度地提高其脱汞效率,且以碘改性膨润土的脱汞效果最好;碘改性吸附剂中添加适量的硫酸后,膨润土负载壳聚糖吸附剂的脱汞效率从85%提高至100%,因与膨润土负载壳聚糖不同的物理化学特性,碘和硫酸改性的膨润土的脱汞效率则降低。     

A radiochemical neutron activation analysis method for the determination of total mercury in coal

A radiochemical neutron activation analysis method has been developed based on pyrolysis followed by double gold amalgamation for the determination of mercury in solid samples. Accurate results were obtained for mercury in six standard reference materials of varying matrices, including coal. Linearity was demonstrated up to mercury concentrations of 10,000 ng/g. The method is capable of yielding precise, reproducible values with a detection limit of 5 ng/g for mercury in coal.     

Wastewater treatment with new activated charcoals to remove butanol

Adsorption of butanol under static conditions on two types of activated charcoals, prepared from birch and a blend of oak and beech, was studied. The adsorption on birch charcoal was carried out under dynamic conditions. The limiting stage of the process was determined. The dependence of the purification efficiency on the fractional composition of activated charcoal and the feed rate of the contaminated solution was studied. The regeneration of birch charcoal with steam and by calcination was performed.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 9, 2004, pp. 1525–1527.Original Russian Text Copyright © 2004 by Krivosheev, Komarova, Poletaeva, Lebedev, Lavrinenko.     

芬顿预处理对木质素快速热解甲氧基脱除规律研究

采用不同H₂O₂含量的芬顿溶液对碱木质素进行预处理，并结合快速热解，探究轻质生物油中含甲氧基化合物含量的变化规律，同时研究了芬顿溶液对木质素结构的影响规律。结果表明，轻质生物油中含甲氧基团的酚类化合物峰面积从AL（未处理碱木质素）的7.3×10⁹下降至13-FML（H₂O₂含量为13 mL/g芬顿溶液预处理碱木质素）的5.2×10⁹，减少了0.29倍。而含甲基团和乙基团的酚类化合物峰面积从AL的3.9×10⁹上升到13-FML的7.2×10⁹，增加了0.85倍。同时，轻质生物油产率从22.4%提高到28.7%。通过FT-IR、¹H NMR和¹³C NMR分析发现，芬顿预处理使木质素凝缩性结构单元减少，甲氧基含量降低，为后续快速热解产生低甲氧基含量的生物油提供了有利条件。