Optimization of carbonization conditions for needle coke production from a low-sulphur petroleum vacuum residue

The optimum carbonization conditions for converting a low-sulphur petroleum vacuum residue in a tube bomb in terms of pressure and temperature into better needle coke of low CTE, with less production of poor bottom coke, were studied by observation of the resultant cokes and sequential analyses of carbonization intermediates by means of solvent fractionation and gas evolution. Carbonization at 460°C under 15 kg cm^–2 G produced the best needle coke. The quality of the resultant needle coke was strongly influenced by viscosity changes of the system, the solidification range and gas evolution in the carbonization progress. The first two characteristics reflect the rates of condensation (such as QI formation) and devolatilization of soluble fractions, strongly influencing the growth of anisotropic units. The last characteristic reflects the pyrolytic cracking reaction to define the timing of gas evolution during carbonization, influencing the axial orientation of anisotropic texture as well as the porosity in the resultant coke. Both profiles varied very much, depending on the carbonization temperature. Finally, the formation of a bottom coke of fine mosaic texture is discussed from the viewpoint of the co-carbonization concept.     

Carbonization of coal-tar pitch into lump needle coke in a tube bomb

The carbonization of coal-tar pitches and their QI (quinoline insoluble)-free fractions was studied by evaluating their lump cokes produced in a tube bomb at various temperatures (470 to 550° C) and pressures (0 to 75 kg cm^–2 gauge). The lump coke from QI-free fractions had a comparable anisotropic development and coefficient of thermal expansion (CTE). The carbonization temperature and pressure were found to influence strongly the properties of the cokes. At the highest temperature of 550° C, the most appropriate pressure for the best needle coke was 15 kg cm^–2 G (gauge). Either higher or lower pressure increased the CTE value of coke. In contrast, at a moderate temperature of 500° C, the higher pressure produced the better coke. At the lowest temperature of 470° C, it took 10 h to complete the carbonization, and the lowest pressure allowed the best extent of uniaxial arrangement. Among the cokes prepared under the present conditions, the Carbonization at 500° C under 40 kg cm^–2 G produced the best needle coke with a CTE value as low as 0.1 × 10^–6° C^–1. The carbonization scheme leading into the needle coke is discussed for a better understanding of how the carbonization temperature and pressure cooperatively influence the quality of the resultant coke, in relation to the carbonization reactivity of coal-tar pitch.     

Binderless moulding of green cokes delivered from solvent refined coal and ethylene tar pitch

Green cokes, derived from the co-carbonization of Solvent Refined Coals with ethylene tar pitch, have been moulded into discs without using a binder. Cokes with a range of size of optical texture have been prepared by control of the ratios of the two components of the carbonization blend. The appearance of the discs was assessed by optical and scanning microscopy after calcination to 1200° C. The most acceptable disc was prepared by moulding carbon of a heat treatment temperature (HTT) of 440° C. With cokes of HTT< 440° C excessive dilation adversely decreased the density of the disc. With cokes of HTT > 440° C, dimished cohesion of the coke grains prevented the development of a strong disc on calcination. It is considered that the presence of benzene-soluble (BS) and benzene-insoluble/quinoline-soluble (BI/QS) fractions in the pitch systems contribute to cohesion of coke particles having a HTT of 440° C.     

为化剂对沥青浸渍性能的影响

通过采用常压热缩聚、压力热缩聚、硫氧化等常规工艺和以呋喃树脂、均四甲苯和石油沥青为共炭化剂进行共炭化的方法对煤沥青改性,比较了不同工艺和不同共炭化剂对改善沥青浸渍剂综合性能的效果,希望提高沥青浸渍剂产炭率的同时使沥青仍保持良好的流动性。研究结果表明,硫氧化法使沥青产生了过度的交联,很高软化点的沥青只具有较低的产炭率水平;压力热缩聚可以得到综合性能较好的浸渍剂沥青。而通过选用合适的共炭化剂,可以进一步改善沥青浸渍剂的综合性能;石油沥青共炭化在经济上具有一定的优势。     

石油渣油制备针状焦研究--中间馏分热反应研究

石油渣油的组成复杂,分子量分布宽,直接焦化不能生产针状焦。采用一定的预处理技术将渣油中适宜制备针状焦的组分保留,可获得理想的焦化原料。通过以辽河减压渣油为原料,经溶剂萃取对渣油进行"掐头去尾"处理,获得了分子量分布窄、杂质含量少的中间馏分A及馏分B。对馏分A、B分别进行热反应研究,结果表明:渣油的预处理效果明显,中间馏分热反应产物具有光学各向异性物含量高、取向性好等特点,是制备针状焦的理想原料。     

石油沥青对煤焦油沥青焦结构和电性能的影响

为了研究石油沥青(PP)作为煤沥青添加剂对沥青焦结构及导电性能的影响,将精制煤沥青(RCTP)与PP混合共炭化,同时在机械搅拌的作用下制焦,并对共炭化过程中PP和机械作用产生的影响机理进行了探讨和分析.采用偏光显微镜、X射线衍射仪、热重分析仪、比表面分析仪对所制半焦的结构进行了分析,利用电化学石英晶体微天平及电阻率仪对所制针状焦的性能进行了考察.结果表明:当PP质量分数为10%、搅拌速率为100 r/min、以间歇搅拌方式所制针状焦,其纤维组织占比达到了67.9%,电阻率降为676Ω·mm~2/m,即PP和机械搅拌二者联合作用存在下可显著增加中间相各向异性组织和纤维组织的含量,有利于改善半焦结构,使其结构更加趋于有序,所得针状焦电阻率也得到明显降低.     

高附加值石油焦新材料

石油焦是一种廉价的石油副产品，主要成分为碳。在快速发展的材料科学中，石油焦作为碳源材料显示出独特的作用，可以用来制备包括高比表面积活性炭、纳米碳化物材料、先进复合材料、电流变材料和锂离子电池负极材料等在内的新材料。这些利用途径都大大提高了石油焦的附加值，具有较大的经济效益，是石油焦传统应用领域以外的引人注目的新的应用途径。     

粒状增强体种类对沥青基炭复合材料性能的影响

采用普通液压机及新型的模压半炭化成型工艺,在大气环境下制备出了高密度、低成本、应用广的三种焦炭(冶金焦、沥青焦Ⅰ和沥青焦Ⅱ)颗粒增强的沥青基炭复合材料(简称PCCs).通过对PCCs材料先后进行快速焙烧处理,沥青浸渍-炭化致密化处理和高温石墨化(2373K)处理,制得了PCC材料的焙烧样品、致密化样品和石墨化样品.通过力学性能试验,SEM和XRD等方法,研究了增强体焦炭颗粒的种类对沥青基炭复合材料的体积密度和抗压强度的影响.结果表明:PCCs材料抗压强度的高低,除了与其体积密度相关外,还与其所采用的增强体焦炭颗粒的耐压强度、微观结构和表面状态有密切的关系.焦炭颗粒的耐压强度愈高、表面越粗糙、开孔孔隙越多,其对沥青基炭复合材料的增强作用也就越显著.无论PCCs材料是焙烧样品、致密化样品、还是石墨化样品,用磨碎冶金焦制备的PCCs材料的三种样品的抗压强度最大,用沥青焦Ⅱ制备的PCCs材料的次之,用沥青焦Ⅰ制备的CRPCC材料的最小.粒状增强体的种类对CRPCC材料的力学性能不仅具有非常重要的影响,而且其强度也具有一定的遗传性.     

炭化压力对沥青成焦形貌及航空刹车用C/C复合材料浸渍增密效果的影响

将武钢中温沥青和太钢高温沥青在不同压力下炭化，进一步对所得沥青焦进行了高温热处理，利用扫描电子显微镜（SEM）和光学显微镜观察所得沥青焦形貌。结果表明；低压炭化时，沥青焦体积密度小，疏松、多大孔，主要为流线区域型各向异性结构；高压炭化时，沥青焦体积密度明显变大，孔变小且均匀分布，主要为小区域和细镶嵌型各向异笥显微结构。考察了不同炭化压力对浸渍增密航空刹车用C／C复合材料的增密效率的影响，结果显示，对整个沥青而言的宏观残炭率明显高于只针对样品而言的实际残炭率，因此有必要进行高压浸渍／炭化实现快速增密。利用XRD和显微硬度测试仪检测了不同炭化压力所得沥青焦热处理后的石墨化度和显微硬度，发现高压下形成的沥青炭更难于石墨化，但石墨化度与显微硬度的热处理后的粗糙层（RL）CVD炭有较好的可比性。     

预炭化对KOH活化石油焦的结构及电容性能的影响

以不同温度炭化的石油焦为原料、KOH为活化剂制备电化学电容器用炭电极材料. 采用XRD、TEM和N₂吸附法对前驱体及活化产物的结构进行了表征, 并考察了样品的电化学性能. 结果表明: 通过调整前驱体的预炭化温度, 可实现对石油焦基活性炭的微晶结构和孔结构的调控, 分别制得无晶体特性的高比表面积活性炭和由大量类石墨微晶构成的低比表面积活性炭. 低表面积活性炭依靠充电过程中电解质离子嵌入类石墨微晶层间而实现能量存储, 具有比高比面积活性炭高10倍的面积比电容和更大的体积比电容.     

Structural changes during pitch-based carbon granular composites carbonisation

This article deals with the study of carbon composites behavior during their carbonization. Composites were prepared using four granular carbons (graphite, anthracite, green petroleum coke, and foundry coke) and four pitches (a commercial impregnating coal-tar pitch, an air-blown and two thermally treated pitches). The evolution of the optical microstructure, porosity, volume, and weight of carbon composites was monitored at different intermediate carbonization temperatures (350, 500, 700, and finally 1000 °C). The porosity of composites increases with carbonization due to volume changes and weight loss of pitches. Weight loss of carbon composites during their carbonization mainly depends on the pitch characteristics and it was slightly influenced by the presence of granular carbon. On the other hand, carbon composites with the commercial coal-tar pitch and foundry coke, anthracite, or graphite deform in the initial stages of carbonization (<350 °C) probably due to the lower porosity of the green pellets and the high amount of low-molecular weight compounds of the pitch. Carbon composites with green petroleum coke underwent important dimensional changes during their carbonization, expanding initially and then shrinking at temperatures above 700 °C. The type of granular carbon strongly influenced the microstructure of the final carbon composite, as a result of its effect on the development of mesophase. Graphite, anthracite and foundry coke delays mesophase development, whereas green petroleum coke accelerates mesophase formation.     

Reactor Graphites Based on Inexpensive Raw Materials

Data are presented on the performance characteristics and properties of Russian-produced graphites molded with inexpensive fillers—electrode, schistose, and pitch cokes. Replacement of petroleum coke, used earlier, by these cokes ensures performance parameters that meet the relevant specifications.     

原料粒度对石油焦基活性炭性能的影响

以不同粒度范围的石油焦为原料,KOH为活化剂,采用化学活化工艺制备了超级电容器用活性炭电极材料.采用N2吸附法表征了活性炭材料的BET比表面积及孔结构;在1mol/L的Et4NBF4/AN有机电解液体系下组装成模拟电容器,并考察了活性炭材料的电化学性能.结果表明:随着原料粒度的减小,活性炭的振实密度和收率先增大,然后再减小.原料粒度范围越窄,活性炭具有越小的BET比表面积和孔容.在1mol/L的Et4NBF4/AN电解液体系下,随着石油焦粒度的不断减小,活性炭材料的质量比容量不断增大,在粒度<38μm时取得最大值140F/g.粒度为38～44μm的石油焦制备出的活性炭在1A/g电流下质量比容量为126.6F/g,在20A/g电流下质量比容量为116.2F/g,容量衰减只有8.2%,表现出良好的功率特性.     

高比表面积活性炭的制备及其吸附性能的初步研究

以石油焦为原料,采用ＫＯＨ化学活化法,在不同的活化条件下对石油焦进行活化。研究原料粒度、活化温度以及活化时间对所制得的活性炭的比表面积及孔结构的影响。结果表明：以石油焦为原料可以制得比表面积为３３００ｍ２／ｇ的高比表面积活性炭。活性炭的孔径分布较窄,其碘吸附值和苯吸附值均较常规活性炭有大幅度提高。     

针状焦和沥青焦用作锂离子电池负极材料的电极性能

研究了针状焦、沥青焦原料的物化性质对其石墨化样品的微结构及其用作锂离子电池负极材料电极性能的影响机制。研究结果表明:(1)因针状焦在制备过程中存在沥青的净化以及中间相的形成、融并和有序排列过程,导致在相同石墨化条件下,针状焦比沥青焦更易于石墨化;(2)经2800℃石墨化处理后,针状焦的d002、La、Lc值分别为0.3373nm、56.05nm、27.11nm,而石墨化沥青焦的La、Lc仅为石墨化针状焦的53.4%;(3)石墨化针状焦经反复充放电40次后,其嵌锂容量能稳定在301mAh/g,而石墨化沥青焦却只有240mAh/g。     

Densification of raw coke powder compacts

The effects of grinding on densification of a petroleum raw coke were examined. The compact of the powder ground for a short time showed large puffing during calcination below 400 °C, and no densification by subsequent heat treatment. It was found that the puffing could be suppressed by long grinding of the powder. In the compact of the powder subjected to prolonged grinding, the pore volume decreased in two temperature ranges of calcination, at 400–500 and 600–700 °C. The first decrease seems to be attributed to softening and volume reduction due to carbonization of quinoline-soluble components among the coke grains. The second decrease suggests that the sintering due to solid state material transport, such as viscous flow and plastic deformation, takes place in addition to gas-phase material transport. The increase in bulk density at temperatures over 1000 °C was mainly due to contraction of constituent grains in which micropores decreased, not a decrease in pore volume of the compact. The most remarkable effect of grinding on densification of the raw coke was the suppression of puffing during the calcination process.     

The texture and strength of metallurgical coke

Attempts to relate the tensile strength of pilot-oven cokes, of blast-furnace quality, to their textural compositions, i.e. the proportions present of the various textural components identifiable in polished coke surfaces under polarized light are described. Of the various equations used, a relationship obtained by multi-linear regression (MLR) analysis permitted the strengths of the cokes from 44 blended coal charges to be calculated with the highest precision but gave no insight into coke breakage behaviour. Equations were therefore derived from consideration of a simple structural model of coke failing in tension by intergranular and transgranular mechanisms. Although predicting coke strengths from textural data with lower precision than the MLR equation, these equations permitted the ready identification of those textural components associated with high strength. Transgranular fracture was indicated as the more probable failure mechanism. A small improvement in precision was obtained by taking the porosity of the coke into account.     

原料配比对石墨材料热传导性能的影响

以煅烧石油焦和煤沥青为基本原料，采用热压工艺制备了一系列石墨材料，考察了煅烧石油焦填料的粒度分布以及粘结剂用量对石墨材料的传导性能的影响，并阐明了粘结剂与填料粒子在热混捏与热压过程中相互作用原理。结果表明：石墨材料的传导性能不仅依赖于原料种类，粒度，而且与其质量配比有关，有最佳原料配比所制备的块状石墨具有高密度，低孔率，低电阻以及高导热等特点；填料煅烧石油焦颗粒以及粘结剂用量的过多或过少，都不利于石墨材料的传导性能，本文填料中最佳煅烧石油焦颗粒用量为25%，原料中最佳粘结剂含量为25%。     

Recycling petroleum coke in blended cement mortar to produce lightweight material for Impact Noise Reduction

This work introduces a new way to use low-cost petroleum (pet) coke as lightweight aggregate in cement mortars to make sound barriers. The feasibility of adding pet coke in cement matrix was investigated: an in-depth characterization of as-received coke and the new lightweight mortar was made. The acoustic behaviour herein was assessed by constructing a large dimension mortar slab (made of cement and coke as aggregate) used as floor covering and measuring, according to the procedure described in international standards, the impact noise pressure level over the range of frequencies 100–5000 Hz. Impact Noise Reduction (INR) was also obtained and the results were compared to the ones experimentally obtained from a control mortar slab (made of cement and sand). Results showed that coke addition leads to a decrease in mechanical properties of resultant mortars, this is principally due to an increase of the porosity (～60%). A gradual increase of impact noise insulation was observed in lightweight floor covering from middle to higher frequencies tested, reaching, within this range, a remarkable improvement of sound insulation compared to control slab (～14 dB).     

Recycling petroleum coke in blended cement mortar to produce lightweight material for Impact Noise Reduction

This work introduces a new way to use low-cost petroleum (pet) coke as lightweight aggregate in cement mortars to make sound barriers. The feasibility of adding pet coke in cement matrix was investigated: an in-depth characterization of as-received coke and the new lightweight mortar was made. The acoustic behaviour herein was assessed by constructing a large dimension mortar slab (made of cement and coke as aggregate) used as floor covering and measuring, according to the procedure described in international standards, the impact noise pressure level over the range of frequencies 100–5000 Hz. Impact Noise Reduction (INR) was also obtained and the results were compared to the ones experimentally obtained from a control mortar slab (made of cement and sand). Results showed that coke addition leads to a decrease in mechanical properties of resultant mortars, this is principally due to an increase of the porosity (∼60%). A gradual increase of impact noise insulation was observed in lightweight floor covering from middle to higher frequencies tested, reaching, within this range, a remarkable improvement of sound insulation compared to control slab (∼14 dB).