由褐煤新法干馏半焦制备炭分子筛的研究

本文提出由褐煤的固体热载体新法干馏半焦制备空分富氮用炭分子筛的工艺路线.考察了炭化和碳沉积工艺条件对产品空分性能和微孔结构的影响,发现新法干馏半焦是制备炭分子筛的良好的原料.最佳工艺条件下制得的炭分子筛的空分性能可与进口的同类产品相媲美.     

黑山褐煤热解提质特性及其半焦制备高炉喷吹适用性研究

本文通过性能分析及低温干馏研究,主要考察了褐煤干馏升温速率和干馏温度对内蒙黑山褐煤提质半焦性能的影响;并在上述研究的基础上结合喷吹煤性能的要求,对干馏提质所得到的半焦高炉喷吹适用性进行了分析。研究表明,内蒙黑山褐煤在600℃和750℃干馏温度下,干馏30分钟后,提质后得到的褐煤半焦完全满足普通喷吹煤和特级喷吹煤的主要指标。该研究为潞安喷吹煤添加提质改性褐煤工艺研发提供了理论基础和设计依据。     

褐煤低温干馏及产物的利用

介绍了褐煤的性质及褐煤提质的常规方法。重点介绍了国内外褐煤低温干馏的典型工艺、特点及开发应用现状。分析了干馏工艺中不同的加热方式、热载体类型以及干馏条件对干馏过程和产品的影响。阐述了褐煤低温干馏产品-褐煤半焦、低温煤焦油以及焦炉煤气的综合利用途径。基于目前国内外褐煤低温干馏工艺大多数处于试验或示范性装置运营阶段,未实现大规模运行,指出未来褐煤低温干馏工艺应走大型化、多联产的新型工业化道路,进一步拓宽干馏产品的应用领域,提高其附加值和利用率,才能实现褐煤资源综合效益最大化和可持续发展。     

热解条件对白音华褐煤半焦孔隙结构的影响

以内蒙古白音华褐煤为研究对象,在管式炉中进行了低温热解实验,考察了低温干馏后原煤和固体产物半焦的结构组成变化,分析了干馏条件对固体产物半焦孔隙结构的影响规律.对原煤和不同干馏条件下半焦的吸附/脱附等温曲线的分析结果表明,半焦具有较宽的孔隙分布,而且中孔和微孔占据了很大的比例;对半焦的孔隙特性参数的测定结果表明,干馏终温和保温时间对半焦的比表面积、孔容积和平均孔径都具有较大的影响.     

基于步进式篦床的褐煤干馏提质系统研发

提出了一种基于步进式篦床工作方式的褐煤干馏提质系统。该系统针对小颗粒褐煤进行干馏提质,通过步进式篦床输送褐煤依次经过干燥段、干馏段、余热回收段和冷却段4个工作区域,实现褐煤的干馏提质,得到煤焦油和半焦产品,可有效地提高褐煤的利用价值。     

SH2010型内热式干馏炉在褐煤干馏中的应用

为了综合高效利用褐煤,陕西冶金设计研究院有限公司开发了褐煤干燥-干馏联产工艺。介绍了该工艺的核心设备立式干燥炉和SH2010型内热式干馏炉的工艺流程、工作原理以及褐煤干馏煤气净化与煤焦油回收工艺。结果表明:为了降低褐煤与高温含氧烟气在立式干燥炉中爆炸的可能,需要在干燥炉顶部设防爆板且进料粒度不能大于150 mm。SH2010型内热式干馏炉使褐煤基本干馏完全,提高了褐煤发热量,后续的配套净化工段回收了大部分的煤焦油与煤气。     

中国褐煤提质技术现状及发展趋势

介绍了国内外典型的褐煤干燥提质技术和褐煤干馏技术以及这两类技术的优缺点。阐述了中国褐煤提质市场和主要干馏工艺的发展建设现状,总结了中国褐煤提质工业的发展情况。2008_2012年,中国干馏提质项目明显增加,而干燥提质项目数量基本稳定,多用于坑口电厂的电煤干燥;2010年项目总量和投资额出现低点,2011年以后,中国褐煤提质项目投资额成倍增长。阐述了目前国内主要的褐煤干馏提质项目主要有国富GF褐煤提质工艺、LCC提质工艺、DG工艺直立炭化炉工艺、ZDL工艺等,并对各项目的应用情况进行对比。最后提出了中国褐煤提质技术的发展趋势主要为：减少褐煤直接燃烧,加大褐煤提质再利用;以褐煤干馏提质为主,辅以干燥提质;褐煤资源的多联产梯级利用逐步成为褐煤资源利用的主导;褐煤提质装备系统大型化将是褐煤综合利用系统装备开发的发展主流。     

中国褐煤干馏的利用前景

中国目前能源结构形式决定了储量相对丰富的褐煤资源将是未来可利用的主要能源。基于褐煤水分高、热值低、易风化自燃但其挥发分高、活性好、氢碳原子比高的独特性质,是作为干馏转化的理想原料,探讨了褐煤干馏转化对保障煤化工产业可持续发展、环境保护及能源安全的重大意义;并对褐煤干馏转化的必要性、市场前景进行了分析。     

褐煤新法干馏

褐煤含挥发分高 ,适于转化利用。简单介绍了 1 50 t/ d平庄工业试验褐煤固体热载体低温干馏 (新法干馏 )工艺流程。讨论了干燥 ,混合 ,气固分离和灰熔温度。中国年轻煤多 ,有利于发展新法干馏技术。     

褐煤干燥—干馏工艺技术研究

介绍了锡林郭勒盟褐煤褐煤干燥—干馏联产工艺技术,利用该技术生产得到褐煤半焦及其附产品,取得了良好的经济价值。     

Microstructural variations of lignite,subbituminous and bituminous coals and their high temperature chars

Microstructure of a North Dakota lignite, a Washington subbituminous and a New Mexico bituminous coal and their chars produced by devolatilization in nitrogen at 1000 to 1300°C was investigated in this work using the CO₂ adsorption method conducted at 25°C. For each coal and char, specific surface area, micropore volume, micropore surface area, mean equivalent radius of micropores and characteristic energy of adsorption, as well as micropore volume distribution, were determined, and their variations with devolatilization temperature studied and interpreted. It was found that, overall, specific surface areas, micropore volumes and micropore surface areas of chars decreased monotonically as devolatilization temperature was raised from 1000 to 1300°C, although most of these values were much larger than that of their parent coals. The micropore volume distributions of the three coals and their high temperature chars were interpreted and found to provide an interesting insight into the micro structural variations of these coals and chars.     

H2O/O2气氛下胜利褐煤气化半焦的孔隙特性

采用实验室气流床反应器, 在H₂O、O₂及其混合气氛, 900℃条件下进行了胜利褐煤气化实验, 研究了气化半焦的孔隙结构特征。结果表明, 在所有气氛下, 半焦的吸附等温线均属于第II类型, 吸附回线为H3型, 褐煤气化半焦具有连续的较完整的孔体系, 孔隙结构类似。反应气氛影响气化半焦的孔径分布, 半焦中的大孔在3种气氛下均较少, 中孔从多到少的顺序是:H₂O > O₂ > H₂O+1%O₂, 微孔与之相反。在水蒸气气氛下, 随水蒸气浓度增加, 半焦的比表面积先增大后趋于稳定。添加1%O₂后, 比表面积提升30多倍。低浓度O₂气氛下, 随O₂浓度的增加, 比表面积呈线性增长。褐煤转化率与微孔容积和总孔容积的比值以及比表面积的关系式为X=0.196(V_m/V)+45.651, X=0.037S+48.066。     

Development of porosity in brown-coal chars on activation with carbon dioxide

Two petrographic types of Tertiary brown coals, xylitic and earthy, were carbonized, and activated with carbon dioxide between 1123 and 1273 K. The development of porosity in the activated chars was studied by adsorption of benzene and carbon dioxide at 298 K and by mercury porosimetry. The type of brown coal exerts a dominant influence on the properties of the activated chars. The xylitic brown-coal, when compared with the earthy brown-coal, yields products with a higher pore volume and better sorptive properties. Activated chars from the xylitic brown-coal reach a surface area of 800 m² g^?1, contained principally in micropores and very narrow mesopores (radius below 3.0 nm). Dimensions of pores in the activated chars from the earthy brown-coal are less uniform, the mesopores are broader (an important part of them has a radius between 5.0 and 100.0 nm), and micropores are present to a smaller extent; the surface area of these products is between 200 and 350 m² g^?1. Activated chars from both types of brown coals have a well developed system of macropores.     

Importance of carbon active sites in the gasification of coal chars

A demineralized lignite has been used in a fundamental study of the role of carbon active sites in coal char gasification. The chars were prepared in N₂ under a wide variety of conditions of heating rate (10 K min^?1 to 10⁴ K s^?1), temperature (975–1475 K) and residence time (0.3 s–1 h). Both pyrolysis residence time and temperature have a significant effect on the reactivity of chars in 0.1 MPa air, determined by isothermal thermogravimetric analysis. The chars were characterized in terms of their elemental composition, micropore volume, total and active surface area, and carbon crystallite size. Total surface area, calculated from C0₂ adsorption isotherms at 298 K, was found not to be a relevant reactivity normalization parameter. Oxygen chemisorption capacity at 375 K and 0.1 MPa air was found to be a valid index of char reactivity and, therefore, gives an indication, at least from a relative standpoint, of the concentration of carbon active sites in a char. The commonly observed deactivation of coal chars with increasing severity of pyrolysis conditions was correlated with their active surface areas. The importance of the concept of active sites in gasification reactions is illustrated for carbons of increasing purity and crystallinity including a Saran char, a graphitized carbon black and a spectroscopically pure natural graphite.     

混煤热解过程中的表面形态

以管式电炉为热解室,改变热解终温,在惰性气氛下对无烟煤与烟煤的混煤进行快速加热条件下的热解。采用低温氮气吸附方法研究混煤焦表面形态的变化规律。通过对吸附等温线的分析,表明煤焦具有连续、完整的孔隙结构,无定形孔的存在使得吸附迴线存在不闭合的状态。随着热解终温的升高,混煤焦的比表面积先增加后减小;随着烟煤掺混比例的增加,混煤焦的微孔容积和表面积也先增加后减小,A1B2混煤焦具有最大微孔容积和表面积。对煤焦孔隙的分形研究发现煤焦孔隙分形维数与微孔结构关系密切。混煤焦表面形态的变化规律体现了混煤热解的独立性以及相互作用。     

煤拔头中低温快速热解烟煤半焦的孔隙结构

利用喷动载流床模拟煤拔头工艺,在550, 650, 750和850℃热解温度下对大同烟煤进行热解得到拔头半焦. 采用氮吸附法对该烟煤及其半焦的孔隙结构进行了研究. 结果表明,拔头半焦的孔隙发达度都弱于原煤;由低到高4个热解温度下挥发分析出率(Y)依次为7.89%, 21.79%, 22.12%, 39.33%,中孔尺寸随Y增加而减小,微孔和大孔尺寸及总孔体积和总孔比表面积基本随Y增加而增加;550℃时挥发分的析出对孔隙结构的发展无明显有利影响. 从原煤到半焦(热解温度由低到高),样品满足BET吸附等温式的相对压力范围依次为0.101~0.351, 0.093~0.201, 0.072~0.152, 0.032~0.053, 0.058~0.108,BET比表面积与NLDFT总孔比表面积变化趋势一致.     

氮吸附法和压汞法测量生物质焦孔隙结构的比较

采用氮吸附法和压汞法对四种生物质焦（稻壳、树叶、玉米杆、棉花杆）的孔隙结构进行了测量,得到了两种测量方法下焦样的比表面积和孔径分布。结果表明不同测量方法得到的焦样比表面积和孔径分布有明显差别。氮吸附法主要测量焦样中微孔的孔隙结构,压汞法主要测量焦样大孔（和部分中孔）的孔隙结构。微孔对焦样的比表面积贡献最大,大孔对焦样的孔容积贡献最大。当热解温度升高时,焦样的微孔结构迅速增多,氮吸附法测得的比表面积变化大;而热解温度对大孔的影响较小,所以压汞法测得的比表面积变化不大。     

Formation of the pore structure of brown coal upon thermolysis with potassium hydroxide

The pore-structure characteristics of active carbons prepared by the thermolysis (800°C) of brown coal impregnated with potassium hydroxide were studied. The dependence of the specific surface area, total pore volume, micropore volume, micropore fraction, and micropore size distribution on the KOH/coal weight ratio R _KOH ≤ 1.0 g/g was found. Condensation processes with the formation of a low-porosity material were predominant at low ratios of R _KOH ≤ 0.1 g/g. The development of a micropore structure was observed at R _KOH ≥ 0.1 g/g, and it increased as R _KOH was increased to 1.0 g/g. It was hypothesized that pore formation was due to the thermally initiated reactions of the structural fragments of coal with KOH molecules, which occurred within the framework of coal.     

煤焦中灰成分对甲烷裂解的影响

利用煤焦作为催化剂,采用小型石英管固定床为反应装置,对甲烷在煤焦、脱灰煤焦、煤灰以及石英砂床层上在温度为1123 K下的裂解反应进行了较为详细的研究。甲烷在脱灰煤焦上和新鲜的褐煤焦上的转化率和氢气收率有一定的差别。煤灰作为催化剂时,甲烷初始转化率和氢气初始收率分别为9.81%和8.14%。表明煤焦中的灰成分对甲烷裂解有一定的影响。随着反应时间的增加,甲烷的转化率和氢气的收率都逐渐降低。通过扫描电子显微镜和比表面积测定仪对反应前后的褐煤焦、脱灰煤焦进行了表征。甲烷裂解后煤焦比表面积、微孔容都明显降低,平均孔径增大。说明甲烷裂解生成的积炭堵塞煤焦的微孔。SEM照片显示甲烷裂解后积炭覆盖在煤焦的表面,使煤焦的催化活性逐渐降低。     

Variation of the pore structure of coal chars during gasification

The variation of the pore structure of several coal chars during gasification in air and carbon dioxide was studied by argon adsorption at 87 K and CO₂ adsorption at 273 K. It is found that the surface area and volume of the small pores (<10 Å) do not change with carbon conversion when the coal char is gasified in air, while those of the larger pores (10-20 Å, 20-50 Å, 50-2500 Å) increase with increase of carbon conversion. However in CO₂ gasification, all the pores in different size ranges increase in surface area and volume with increase of carbon conversion. Simultaneously, the reaction rate normalized by the surface area of the pores >10 Å for air gasification is constant over a wide range of conversion (>20%), while for CO₂ gasification similar results are obtained using the total surface area. However, in the early stages of gasification (<20%) the normalized reaction rate is much higher than that in the later stage of gasification, due to existence of more inaccessible pores in the beginning of gasification. The inaccessibility of the micropores to adsorption at low and ambient temperatures is confirmed by the measurement of the helium density of the coal chars. The random pore model can fit the experimental data well and the fitted structural parameters match those obtained by physical gas adsorption for coal chars without closed pores.