Capillary flow of liquid pitch

The capillary flow of liquid pitch into a granular coke bed has been theoretically investigated. An equation relating the flow rate with temperature has been derived considering the pitch as a Newtonian liquid. For a given coke granulometry, the wetting angle and the viscosity of the pitch material are the most important factors governing its flow properties. A comparison with experimental flow measurements indicates that some pitches penetrate into the granular coke bed according to the developed equation of flow.     

Correlations between ability of pitch to penetrate coke and the physical characteristics of prebaked anodes for the aluminium industry

The nature of the interaction between coke and pitch is basic to the final properties of anodes for the aluminium melting industry. One of the significant properties of pitch which contribute to the quality of this binding is its ability to wet coke. The investigations reported here indicate the optimum experimental conditions for the use of an automatic apparatus that monitors pitch penetration into a coke bed. The penetration test described can be used to select pitches with good affinity for petroleum coke and to correlate this quality with the physical properties of electrodes produced therefrom. A particularly important conclusion is that the test suggests the suitability of certain pitches which would not satisfy the usual selection criteria. The temperature-dependent ability of a pitch to penetrate a coke bed, in conjunction with the traditional criteria, assists in the selection of binder pitches used in the aluminium industry.     

Pitch-coke interactions

Penetration of molten pitch into a coke bed is correlated with thermodynamic properties of pitch and of pitch-coke interfaces, as well as with the rheology of the liquid. A review of the possible relation between the above properties and the molecular properties of the pitch is presented.     

活性焦颗粒在矩形移动床中流动特性的试验研究

固体颗粒在移动床内的流动特性是影响床层使用效率的一个关键性因素。本文通过对活性焦在矩形移动床中流动特性的试验研究,确定了要满足活性焦颗粒在床层内为整体流其下料斗的倾角大小,以及颗粒在下料斗上部为平推流的临界高度,并研究了内构件对移动床内颗粒流动的影响,为合理设计和有效利用床层提供指导。     

Desulphurization of petroleum coke by butagas

The work described concerns the desulphurization of Egyptian petroleum coke by butagas in a fixed-bed reactor. Optimum values for reaction temperature and coke particle size were observed; but increased gas flow rate, prolonged reaction time, and decreased coke bed depth all favoured increased sulphur removal throughout the ranges studied. The effects of the different factors could be interpreted satisfactorily in terms of the thermodynamic potential of the desulphurization reaction and the diffusion of gases into and out of the coke particles. While gas/coke ratio governs the former, the latter is mainly influenced by sintering of the coke particles. For comparison, some desulphurization runs were carried out using hydrogen in place of butagas, and Syrian petroleum coke instead of the Egyptian coke. The Syrian coke proved difficult to desulphurize.     

沥青种类和焦炭粒度组成对焦炭颗粒增强沥青基炭复合材料性能的影响

采用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、低成本的焦炭颗粒增强沥青基炭复合材料（简称CRPCC材料）。研究了煤沥青的种类、沥青焦中添加冶金焦以及焦炭颗粒的粒度组成配比对CRPCC材料的密度和抗压强度的影响。结果表明：煤沥青的软化点高，用其制备的CRPCC材料的密度和抗压强度未必就高；沥青焦中添加一定含量的冶金焦，则可制备出密度和抗压强度更好的CRPCC材料。     

Research on high-quality pitch-based materials

A method of continuous solvent fractionation of coke oven tar to make an insoluble pitch and an oil fraction has been demonstrated. The distillation residue of the oil fraction (oil pitch) can be further processed to give high-quality electrode coke, carbon fibre precursor, composite-impregnating pitch or components for tar/resin paints. The insoluble pitch gives pitch coke suitable for anode manufacture. Thermal treatment of mixtures of the insoluble pitch and the oil pitch facilitates the production of a wide range of electrode binders and impregnating pitches.     

Needle coke formation derived from co-carbonization of ethylene tar pitch and polystyrene

Ethylene tar pitch was co-carbonized with waste polystyrene to prepare needle coke. The modified properties of mesophase, which were greatly improved due to increasing naphthenic and other alkyl content, availed the formation of needle coke with high quality. The coefficient of thermal expansion value was decreased from 3.2 × 10⁻⁶/°C to 0.3 × 10⁻⁶/°C and the optical texture of the coke was changed from coarse mosaic texture to flow domain of high uniaxial orientation after adding waste polystyrene into ethylene tar pitch. The low viscosity of the mesophase pitches favored the development of mesophase and highly uniaxial arrangement. The increase in alkyl group content greatly improved characteristics of the needle coke.     

Carbonization and liquid crystal (mesophase) development. 14. Co-carbonization of coals with A240 Ashland petroleum pitch: effects of conditions of carbonization upon optical textures of resultant cokes

This study examines the effect of pitch concentration, rate of heating, soak temperature and time of soak upon the optical texture of cokes prepared from the co-carbonizations of a coal (Oxcroft-Clowne, NCB Rank 802) and three vitrains of NCB Rank 204, 801, 902 with Ashland A240 petroleum pitch. Using the coal (Rank 802) with 10 wt % and 25 wt % additions of pitch caused progressive penetration of the pitch into the coal with a resultant development of a mozaic anisotropy in the coke to replace partially the original coke isotropy. With 50 wt % addition of pitch almost all of the coal particles, 600 to 1100 μm in size, were modified during carbonization. Some pitch coke was formed. For the coal and three vitrains with increasing rates of co-carbonization from 0.5–10 K min^?1 to 1200 K, using 25 wt % of A240 pitch, resultant cokes showed progressively increased extents of modification. For the two vitrains (Rank 801, 902) soaking at temperatures of 650–690 K caused a decrease in the extent of modification of isotropic coke when compared with the coke of HTT 1200 K. Evidently fast heating rates create the conditions of fluidity necessary for the pitch to modify the coal leading to growth of mesophase and anisotropic coke.     

Sintering properties of composites consisting of carbon filler and binder

The sintering properties of composites consisting of coke and coal pitch are considered. The coke yield from pitch cannot be used to assess the sintering properties. The increase in coke yield from the pitch in the presence of filler is found to be correlated with increase in sintering properties and strength of the composite.     

Carbonization and liquid-crystal (mesophase) development. 22. Micro-strength and optical textures of cokes from coal-pitch co-carbonizations

This study examines the micro-strength and optical textures of a laboratory coke from a base-blend of Freyming and Pocahontas coal (wt ratio, 1:1) and of cokes from the co-carbonization of the blend, with each of five petroleum pitches in various proportions. Coke pieces, 212–600 μm, from the micro-strength test are assessed in terms of origin and propagation of cracks induced by the test. Always, the addition of pitch to the base-blend improves the strength of the resultant cokes, the pitches behaving differently. A qualitative, subjective appraisal of results indicates that increases in coke strength are associated with relative abilities of pitches to interact with the coals to produce a fluid phase, of solution of coal in pitch, which gives an ‘intermediate’ coke with an optical texture of mozaics. This intermediate coke strengthens the bonding at interfaces. Cracks originate predominantly from the shrinkage cracks in the domains of Pocahontas coke. Mozaic structures tend to resist crack propagation. The coal/pitch system may flow around coal particles so containing incipient crack formation in resultant coke particles.     

Three-dimensional modelling of in-furnace coal/coke combustion in a blast furnace

A three-dimensional mathematical model of the combustion of pulverized coal and coke is developed. The model is applied to the region of lance-blowpipe-tuyere-raceway-coke bed to simulate in-furnace phenomena of pulverized coal injection in an ironmaking blast furnace. The model integrates not only pulverized coal combustion model in the blowpipe-tuyere-raceway-coke bed but also coke combustion model in the coke bed. The model is validated against the measurements under different conditions. The comprehensive in-furnace phenomena are investigated in the raceway and coke bed, in terms of flow, temperature, gas composition, and coal burning characteristics. The underlying mechanisms for the in-furnace phenomena are also analysed. The simulation results indicate that it is important to include recirculation region in the raceway and the coke bed reactions for better understanding in-furnace phenomena. The model provides a cost-effective tool for understanding and optimizing the in-furnace flow-thermo-chemical characteristics of the PCI operation in full-scale blast furnaces.     

Production of isotropic coke in industrial trials

The influence of the production conditions on the properties of coke is considered. Coke is produced in a pilot plant at the Institute of Technical Chemistry, Ural Branch, Russian Academy of Sciences, in a 200-L reactor equipped with an air-supply valve and heating elements. The first stage in coke production is air-blowing of the batch with constant temperature rise at 10–12°C/h from 290–310°C; the air flow rate is 45–55 L/kg h. At this stage, the final air-blowing temperature and the batch composition are varied. The second stage is coking, with temperature rise at 25°C/h to 550–600°C. The batch consists of industrial air-blown pitch (ABP), modified by pitch tar (PT). Oxidation of the ABP, even with a very high final temperature (434°C), does not permit the production of isotropic coke. An analogous result is obtained on adding small portions of PT to the batch (15%). On adding >50% PT, totally isotropic coke may be produced. To obtain coke of isotropic microstructure, the optimal content of PT is 36–41%, and the final air-blowing temperature should be high (>390°C). The influence of PT on the structural parameters of the coke is associated with the formation of nonmesogenic structures on air-blowing. On coking, these structures suppress the growth of large mesophase. The isotropic coke produced has the following characteristics: limited expansion in the range 1300–2400°C; high structural strength; and optimal density. Graphite based on such coke is considerably superior to graphite based on industrial pitch coke in terms of its compressive strength, density, and electrical resistivity.     

Structure and carbonization properties of pitches produced catalytically from aromatic hydrocarbons with

Carbonization properties of pitches synthesized from some aromatic hydrocarbons by the aid of were studied under atmospheric 1.1 and 3.1 MPa pressures. The highest coke yields obtained under atmospheric pressure and 3.1 MPa were 64% and 85%, respectively, both of which were observed with anthracene pitch. Pyrene pitch exhibited a low coke yield of 37% under atmospheric pressure, but as high as 85% under 3.1 MPa.The pitches were revealed with ¹H-NMR and FD-MS to consist essentially of oligomers of starting aromatic rings such as dimers, trimers, and tetramers. The oligomers carried significant amounts of naphthenic hydrogens, which provide their low softening point and enable the development of an anisotropic flow texture when the pitch was carbonized. The carbonization scheme is discussed in relation to the coke yield.     

Carbonization properties of carbonaceous substances oxidized by air blowing—II: Acid-catalyzed modification of oxidized residual oil for better anisotropic development

The catalytic carbonization and modification of oxidized residual oils were studied using AlCl₃. Although the catalyst increased the coke yield in the carbonization, the size of the anisotropic units developed in the resultant coke decreased. Modification at proper temperatures was found effective in restoring the potential of the pitch for the anisotropic development of the flow texture. The modified pitch remained essentially quinoline soluble after the above-mentioned modification with only a minor amount of it becoming insoluble. After the modification, some anisotropic units of small diameter were observable in the quinoline soluble phase after separation of the quinoline insoluble phase. These units were recrystallized into smaller numbers of larger units by the gentle evaporation of the solvent quinoline. The significance of the soluble mesophase was discussed.     

沥青粘结剂产炭率对制品性能的影响

研究了粘结剂沥青产炭率与块状炭制品材料性能的关系,拟通过提高粘结剂沥青产炭率的方法改善炭制品的性质。实验采用比目前工业沥青粘结剂产炭率更高的沥青作为粘结剂,经过混捏、成型和焙烧制成炭制品。研究发现,采用产炭率高的粘结剂可以得到性能较好的产品,但对于强度来说,过高产炭率的粘结剂并不总是正面影响的,应考虑到粘结剂中β组分的含量。     

Effect of pitch powder addition on the microstructure and properties of carbon blocks for blast furnace

The phase composition and microstructural evolution of pitch-containing matrix sample with additive of silicon had been compared with pitch-free or resin-containing matrix sample to illustrate the strengthening effect of pitch. Two different pitch powders (CARBORES^@P and High temperature pitch) were then incorporated into carbon blocks, respectively and the effect of pitch powder addition on microstructure and properties of carbon blocks fired at 1000?°C and 1400?°C in a coke bed was evaluated systematically. The results showed that compared with amorphous carbonized resin, carbonized pitch was a kind of highly graphitized carbon and could react with silicon and form SiC whiskers at 1400?°C. In carbon blocks, pitch powder accelerated the formation of AlN at 1000?°C and growth of β-SiC whiskers at 1400?°C, respectively, which enhanced the cold compressive strength, thermal conductivity and hot metal erosion resistance of carbon blocks. Moreover, carbon blocks containing CARBORES^@P pitch with higher carbon yield exhibited better properties because of formation of more ceramic whiskers. The strengthening mechanism of pitch powder for carbon blocks was attributed to the pore-blocking effect of pitch carbonization and more in-situ formed whiskers derived from the reaction between carbonized pitch with silicon at 1400?°C.     

Analysis of stress and buoyancy for solids flow in the lower part of a blast furnace

A quasi-stagnant coke bed formed in the lower part of blast furnace, called ‘deadman’, is replaced by new coke over a long renewal interval. The repetition motion, floating of the hearth coke bed due to buoyancy during storage of the molten material and refilling the bottom space due to descending motion of the coke bed during the discharge, is considered to be one of the driving forces for the deadman renewal motion. The purpose of the present study is to clarify the critical condition for the hearth bed to be forced to float up due to buoyancy. Assuming deadman to be a conical body, the stresses acting at the deadman surface are obtained at first extending Walters’ theory (Walters, Chem. Eng. Sci. 28 (1973a) 13; 28 (1973b) 779) to the diverging shaft and the converging annular flow-channel between deadman and furnace wall under gas flow. In the next place, a stress field in an active state of stress is proposed to predict the distribution of solid load developed in the deadman and lower hearth part. The critical storage level of molten liquid for hearth bed floating is then derived from a force balance between the solids load, buoyancy and wall shear stress. It is found that the floating mode depends on the horizontal profile of vertical load at the critical liquid level. In the case of the load profile is uniform across the cross section, the hearth bed would start to float up leaving a solid-free liquid space with horizontally uniform height. In the case of the vertical load is high in most of the cross section, but becomes lower near the wall, two types are possible for bed motion. Thus, a diagram classifying the floating mode into three categories according to the way the hearth bed behaves at the beginning of floating is given.     

改质沥青配煤炼焦的研究与实践

根据沥青黏结性较好、灰分低的特点,利用40kg试验小焦炉进行沥青配煤炼焦试验,确定配煤方案和配入比例后进行大焦炉试验,最终成功应用于JN60焦炉进行连续生产。沥青配煤的应用,改善了焦炭质量,扩大了配煤的使用范围,降低了焦炭生产成本。     

煤沥青对焦炭的浸润性及其在核石墨制备中的作用

作为炭素材料,核石墨是高温气冷堆和熔盐堆的关键材料.在炭素材料的制备过程中,粘结剂沥青对骨料焦炭颗粒的浸润性对炭素材料的生产工艺以及最终产品的强度、耐磨性都有重要影响.在研究中,人们先后采用润湿角法、液滴测试技术、渗透层厚度法以及结焦实验对煤沥青/焦炭的浸润性进行表征和检测.沥青的化学组分和结构、焦炭的粒度、表面官能团决定了沥青的表面张力、沥青的黏度以及沥青液滴在焦炭基体上的接触角,是影响沥青浸润性的主要因素.提高沥青浸润性的常用方法包括控制沥青组分,采用表面活性剂改变沥青的结构或将润湿沥青和非润湿沥青进行混合.文章的最后对我国国产核石墨研制中煤沥青浸润性的改善途径提出建议.