Co-carbonization of coking coal with K2CO3: structure of the resulting chars

Oakdale coking coal was co-carbonized with up to 30 wt% of K₂CO₃ to 900 °C. The resulting chars were examined for optical texture and morphology by scanning electron microscopy. No changes in optical texture were observed with additions of < 1 wt% K₂CO₃. Increased additions created an isotropic, non-fusing layer of char around the particles and this prevented the formation of a coherent coke. The size of the remaining anisotropy was also reduced, some char fragments being composed of isotropic carbon. Severe fissuring occurred in the particles of char, causing fragmentation; this was presumably due to diffusion of potassium into the char structure. X-ray studies indicated increased peak half-widths of (002) diffractions for the isotropic carbon.     

煤炭低温干馏技术现状及发展趋势

概述了煤炭低温干馏技术的现状以及目前国内的应用情况,并就煤炭低温干馏技术的发展趋势进行了阐述。     

Coal carbonization and coke anisotropy: some comments

Previously published work is presented in modified form to emphasise that, except under special circumstances, spherical mesophase units have not been observed during coal carbonization and that the viscosity of the fluid phase, considered so important during pitch carbonization, has no strong bearing on the size of anisotropic units found in metallurgical coke.     

煤种及炭化条件对活性焦表面化学性质的影响

在不同煤种及炭化条件下,于一间歇流化床上制备活性焦(AC)。使用XPS等分析手段考察不同制备条件下制得的活性焦表面化学性质的差异。研究结果表明,煤种不同制得的活性焦的表面性质相差较大;炭化条件(炭化温度400—800℃、炭化时间0—60min)对最终制得的彬县煤活性焦表面化学性质影响很小。     

煤焦加压气化反应性研究

利用加压热分析仪,测定了义马煤焦的CO2气化反应性。结果表明:随温度的提高,义马煤焦的反应性和反应速度呈增加趋势,与前期研究常压下的情况一致;压力对气化反应的促进作用不明显,且温度对气化过程的影响大于压力;反应速率在初始阶段最大,随后逐渐减小。经过动力学计算表明:反应速率与温度的关系符合Arrhen ius定律;反应级数随温度增加而减小,近似于线性关系;煤焦活化能大约为60.02 kJ/mol。     

Influence of aluminium chloride on carbonization of coal model compounds and coal derivatives

Changes in spin concentration during carbonization of coal model compounds and coal components in the presence of AlCl₃, a known carbonization catalyst, were studied with an e.s.r. spectrometer equipped with a high-temperature cavity. On addition of AlCl₃ the spin concentration during carbonization increased for compounds with three or fewer aromatic rings and decreased for those with four or more. Only the spin concentration of the quinoline-soluble component of a low-reflectance coal increased during carbonization in the presence of AlCl₃. These phenomena are discussed in terms of molecular orbital theory.     

Properties and potential of formed cokes derived from two Turkish lignites by carbonization of binderless briquettes

Two high-sulphur Turkish lignites were briquetted at room temperature under pressures of 113 or 212 MPa and the briquettes were carbonized to 1158–1173 K over special heating cycles. The lower-rank lignite gave a formed coke of superior mechanical strength, lower porosity and higher sulphur content than typical blast furnace cokes. The formed coke produced from the higher-rank lignite briquettes had slightly poorer mechanical strength, lower porosity and much higher ash yield and sulphur content than conventional cokes. The products were considered attractive for use in non-ferrous metallurgy.     

Carbonization of coals to produce anisotropic cokes. 2. Up-grading of modification activities of petroleum process residues and their correlation with structural parameters

Modifying activities of petroleum pitches and up-graded pitches in the co-carbonization with a range of coals have been examined with the object of proposing an effective co-carbonization process for blast-furnace coke production. Up-grading of additives was attempted using thermal, acidic and oxidative reactions. Acidic reactions with aluminium chloride were most effective with lighter petroleum residues of initially poor modifying activity, this being attributed to dealkylation, ring-closure and ring condensation reactions. The relation between modifying activity and structural indices is discussed. The aromaticity (f_a) and the naphthenic ring number in the unit structure T_n,us can be used as appropriate parameters for the activity when the coking yield is taken into account.     

煤焦CO2气化反应动力学研究

在热天平实验装置上进行了霍林河、义马、兖州、平朔、神华、大同6种煤焦的CO2气化反应性实验，实验温度为900～1050℃。通过对实验数据处理，取得了6种煤焦的反应动力学参数等，利用不同的参数对煤焦CO2气化的反应活性进行了比较。     

Possibilities of tar addition to coal as a method of improving coke strength

Tests carried out in a pilot oven, in individual 19-t ovens and for a short time, in a 4.5 m high 54 oven battery, showed that addition of a certain amount of tar directly to any coal mix can improve the coke properties. The experimental procedure adopted for tar addition and the determination of the coke properties are highlighted.     

升温速率及反应温度对焦炭反应性及反应后强度的影响

针对焦炭反应性及反应后强度测试规范性强,测试误差也较大的问题,探索了升温速率及反应温度对焦炭反应性及反应后强度的影响。实验结果表明,随着升温速率的不断的增大,焦炭的反应性在不断的减少,焦炭的反应后强度在不断的增大;小范围改变反应温度,仍对焦炭反应性及反应后强度产生比较显著的影响。升温速率越快,反应初期焦粒内部的温度低于1100℃的幅度就越大,即反应初期焦粒内部在低于1100℃条件下与二氧化碳反应的时间就越长。     

煤与废塑料处理及共焦化应用前景

本文综述了当前处理废塑料的几种方法,结合国外煤与废塑料共焦化的相关研究,提出了煤与废塑料共焦化研究的新方向,以期实现煤与废塑料共焦化工艺。该工艺的初步设想为“废塑料的收集→预处理→与煤共同粉碎→共焦化”,为解决“白色污染”提供一种有效的途径。     

The thermoplasticity of coal and the effect of K2CO3 addition in relation to the reactivity of the char in gasification

The thermoplastic properties of a medium-volatile and a high-volatile A bituminous coal have been studied by means of high-pressure dilatometry as a function of the heating rate (10 and 65 K min⁻¹), particle size (< 44 μm, < 75 μm, 106–200 μm and 212–400 μm) and gas pressure (1–28 bar). The thermoplastic properties of the coals are significantly different at elevated pressures from those at atmospheric pressure. At atmospheric pressure the volume swelling increases strongly with increasing heating rate and, at 10 K min⁻¹, with increasing particle size. At a pressure of 28 bar however, the swelling is nearly independent of heating rate and particle size. The effect of addition of K₂CO₃ (20% by weight) was investigated at 65 K min⁻¹ and turned out to depend on the gas pressure and particle size. At atmospheric pressure, K₂CO₃ reduces the dilatation of the coals almost completely. This reduction decreases with increasing pressure, especially for the larger particle size fraction (212–400 μm). A detailed mechanism for the interaction of alkali metal carbonates with the coal is suggested. The softening and swelling of coal particles has consequences for the available and accessible surface area of the char formed and thus for the reactivity of the char in gasification. Results of reactivity measurements in a CO₂ atmosphere in a thermobalance that illustrate this effect are presented and related to the morphology of the char.     

清洁煤技术与CO_2地质封存

中国能源资源特点决定现在以煤为主的消费结构,但煤炭在消费过程中存在高污染和低效率的问题,因此为提高资源利用率,煤炭行业面临结构调整。煤炭行业的清洁化、高效化、低碳化将是产业发展方向,煤炭高效洁净转化将取代传统的转化技术,如何解决煤炭利用过程中产生的CO2是清洁煤技术面临的新问题。通过研究清洁煤技术与CO2地质封存技术,特别是深部盐水层封存技术,为煤炭利用中产生的CO2排放提供了一种大规模、安全、稳定的存储方式,从而解决目前中国能源结构造成的CO2排放问题。     

Fe2O3和K2CO3对高灰分煤催化燃烧影响及机理分析

为提高淮北矿区高灰分煤的燃烧效率,采用热重分析实验对比分析了Fe2O3和K2CO3对煤粉着火与燃尽温度、燃烧特性指数、放热面积的影响.结果发现Fe2O3和K2CO3可分别将煤粉的着火温度由480.3℃降低470.4℃和397.3℃,燃尽温度由628.4℃降到609.7℃和547.7℃,燃烧特性指数提高,放热量增大.利用SEM、XRD和FTIR测试技术对煤粉燃烧残余物的微观结构、物相组成及官能团变化进行研究,分析燃煤催化剂在燃烧反应中的作用机理;通过BET方程计算燃烧煤焦的比表面积,分析其孔隙结构的变化.结果表明Fe2O3和K2CO3的主要作用机理是促进燃烧反应过程中挥发分的析出,增强煤粉的吸附性能,加快燃烧反应过程中固定碳的燃烧.     

Some physical properties of Canadian coals and their effects on coal reactivity

The pore volume, surface area and compressibility of eleven Canadian coals, varying in rank from lignite to semianthracite, have been determined by mercury porosimetry, gas adsorption method and relations derived from helium and mercury densities. The total pore volume was measured in the diameter range of 0.2 nm–2.98 μm, which was subdivided into two groups, namely the micropore region (< 0.0036 μm) and the combined meso- and macropore region (0.0036–2.98 μm). It has been determined that the porosity of the eleven coals studied varies from 2 to 39%. It has been found that the total pore volume, micropore volume, surface area and the apparent compressibility of these coals decrease with increase in the carbon content, or the rank of the coals. The effect of the total pore volume, micropore volume and surface area on chemical reactivity of the coal is discussed separately. A good correlation was obtained between the carbon content and helium density of the coal after correction is made for the mineral content.     

Carbonization of coals to produce anisotropic cokes. 1. Modifying activities of some additives in the co-carbonization of low-rank coals

Using low-rank coals, the modifying activities of some petroleum, coal tar and aromatic hydrocarbon additives have been examined to find procedures for their utilization in the preparation of blast furnace coke. Petroleum pitch, especially after hydrogenation, exhibited excellent modifying activity even with non-fusible coals. In contrast, the activity of coal tar was very limited with such coals. The napththenic component, revealed by n.m.r. of the additives, appears to be important in the co-carbonization by inducing fusibility and anisotropic development in such coals. Co-carbonization to recover the dehydrogenated additives was attempted. However, there was no development of the anisotropy in the resultant coke by dissolution of the coal particles although the coal particles were firmly fixed in the matrix. Acid-refluxing treatment of non-fusible coals was found to enhance their modification susceptibility, indicating that some of the acid-soluble mineral matter is important in the thermal depolymerization or fusion process of the coal.     

Effect of SO42− on catalytic activity of Fe2O3 for hydrocracking of coal

The catalytic activity of Fe₂O₃for the hydrocracking of a bituminous coal at 673K increases when a small amount of SO₄^2? is included in the catalyst. The effect of SO₄^2? is marked in the formation of resins, stronger polar compounds and asphaltenes.     

秸秆灰对煤焦气化反应性的影响

钾、钙对煤焦气化反应性具有重要影响,秸秆灰中含有丰富的钾、钙。以神木煤为制焦原料,通过STA409PC同步热分析仪研究了秸秆灰对煤焦气化反应性的影响,并通过测定煤焦的碘吸附值对其比表面积及孔隙结构进行了分析。结果表明：煤与玉米秸秆共焦化所得煤焦的气化反应性明显优于单独煤焦,且与玉米秸秆的添加比例有关;采用脱灰玉米秸秆与煤共焦化所得煤焦的气化反应性与单纯煤焦相近;将与玉米秸秆等效的秸秆灰添加到煤焦中,煤焦的气化效果明显优于等效玉米秸秆与煤共焦化所得煤焦。煤焦碘吸附值测定结果表明,脱灰秸秆与煤共焦化所得煤焦的碘吸附值最大,单纯煤焦的碘吸附值最小,说明玉米秸秆及秸秆灰对煤焦的比表面积及孔隙结构具有重要的影响,与煤焦的气化反应性评价结果基本一致。     

O2/CO2燃烧对神华煤Ca和Fe交互反应影响

选用高Ca、高Fe含量的神华煤,在沉降炉系统中进行空气以及O₂/CO₂燃烧实验。利用X射线荧光探针(XRF)、X射线衍射仪(XRD)、先进计算机控制扫描电镜(CCSEM)分别对总灰元素、晶相组成以及主要矿物元素的共生特性进行深入表征。结果表明氧/燃料燃烧促进了Fe、Ca与其他矿物元素的交互反应,总灰中Fe在Fe-rich类矿物分布减少,而在铁铝硅酸盐(Fe-alsil),尤其是在Fe与Ca发生交互反应的Fe+Ca类矿物的分布增加,同时Ca也存在类似的分布规律。对总灰中Fe+Ca类矿物深入分析发现,氧/燃料燃烧条件下总灰中Fe+Ca类矿物结渣倾向更严重(Fe₂O₃/CaO摩尔比为0.5～3)。