Influence of petroleum coking additive on the quality of coal batch,coke, and tar

Given the shortage of coal with good coking properties, a petroleum coking additive is introduced in coal batch so as to expand the range of plasticity. This additive improves coke quality in every respect, except the total sulfur content. Measures to reduce the additive’s negative impact on the coal pitch are considered.     

Oxidation of coke with petroleum-based coking additives

The properties of coking batch may be stabilized by means of DK coking additive based on the products of petroleum pyrolysis, characterized by low ash content (A^d = 0.4%), high sulfur content (S_t^d= 4.1%), and high yield of volatiles (V^daf = 17.2%) relative to coal concentrates. Individual coking of DK coking additive yields a product (particle size >40 mm) with postreactive strength CSR = 77–79%, reactivity CRI = 18–22%, and density 1200–1400 kg/m³. Differential scanning calorimetry of experimental coke samples reveals six stages in their heat treatment in air: preliminary heating, intense oxidation, gasification of carbon, surface combustion of the gaseous products, their flare combustion, and oxidation of the residue. The use of DK coking additive in the coking batch shifts the oxidation process to higher temperatures and ensures the largest interval of heat liberation at elevated heating rate, with up to 50% DK additive. With increase in the content of DK additive from 30 to 50%, the activation energy is increased by 4.56 kJ/mol for each additional 10%. In that case, the supply of atmospheric oxygen to the combustion zone must be improved     

影响焦炭质量的因素分析

焦炭的质量主要取决于配合煤性质和工艺条件。配合煤的性质主要是结焦性、煤的粘结性对焦炭强度的影响较大;炼焦煤的性质影响焦炭的灰分、硫分等化学组成,影响焦炭强度。炼焦的工艺条件是水分、灰分、细度、堆密度等;结焦时间影响焦炭冷态、热态性能和显微特性。     

Influence of batch properties and the final coking temperature on the coke yield

At PAO Zaporozhkoks, the coke yield is determined experimentally as a function of the batch properties and the final coking temperature, in box coking. An empirical formula for the coke yield is obtained. With increase in the yield of volatiles from dry batch by 1%, the coke yield falls by 0.71%. With increase in the final coking temperature by 50°C, the coke yield falls by 0.35%.     

Industrial utilization of spent ion-exchange resin in the coke battery

Experimental coking with spent ion-exchange resins as an additive in the coal batch is considered; rammed batch is employed. Both box coking and large-scale coking are considered; the resin content in the batch is 1–5 wt %. The influence of the resins on coke quality is assessed. The coal blend used in industrial coke production is employed. Adding small quantities of resin (<5 wt %) to the batch improves the coke’s cold strength M ₈₀ and M ₄₀, without impairment of CRI and CSR. The quality of the coal tar and the organized gas emission remains unchanged. Hence, spent ion-exchange resins may be recycled by adding small quantities (3%) to the coal batch in coke production.     

Influence of the coking properties of coal batch on coke properties

At OAO Zapadno-Sibirskii Metallurgicheskii Kombinat (ZSMK), research is undertaken to improve the optimization of coking batch. The basic approach, proposed by specialists from OAO Nizhne-tagil’skii Metallurgicheskii Kombinat, employs the coefficient K _opt, which characterizes the deviation of the batch from its optimal composition. The coking properties of the OAO ZSMK coal batch over the last few years are analyzed. After laboratory and industrial coking of batch with different K _opt, the strength and reactivity of the resulting coke is investigated. Evaluation of coke-grade coal in terms of its rank according to State Standard GOST 25543-88 proves inadequate, since coal of the same rank may differ markedly in coking properties. A method is established for assessing the optimality of the coal batch at OAO ZSMK.     

Effects of weathered coal on coking properties and coke quality

Determinations of weathered coal by petrographic methods, and coking tests in an 18-inch ($\text{≈}\text{1}\text{2}\text{m}$) test oven were used to quantify the effects of weathered coal on coking properties and coke quality. The results show that the presence of weathered coal causes a decrease in coke stability and coking rate and an increase in coke reactivity and coke-breeze generation. Because these effects contribute to increased costs in both the coke plant and the blast furnace, every effort should be made to reduce the amount of weathered coal in coking coal mixes.     

A semi-industrial scale study of petroleum coke as an additive in cokemaking

The addition of petroleum coke to a typical industrial coal blend used in the production of metallurgical coke was studied. Cokes were produced at semi-industrial scale at the INCAR coking plant, using petroleum coke of different particle size distribution as an additive. Special attention was paid to changes caused in the textural properties (porosity, pore size distribution, fissures at the interface between metallurgical coke and petroleum coke) which have been found to be responsible for variations in the metallurgical coke quality parameters (e.g., mechanical strength and reactivity towards CO₂). Variation in porosity was found to depend on particle size and the proportion of the additive. The decrease in the microporosity (i.e., pore radius<3.7 nm) of the metallurgical cokes observed when petroleum coke is added to the coal blend, is postulated to be one of the main factors responsible for the decrease in the reactivity of these cokes. The variation of the mechanical strength indices can be explained by the changes in porosity and the quality of the interfaces between petroleum coke and metallurgical coke.     

Evaluation of coal and its influence on coke quality and the coking process

The evaluation of coal batch is considered, along with its influence on coke quality and the coking properties. The quality of the coal available for coking at OAO Zapadno-Sibirskii Metallurgicheskii Kombinat is declining. Given the shortage of coking coal, coal ranks that are not of equivalent coking and enrichment characteristics are being added to the batch. In some cases, mixtures with energy coals are prepared. The ash content of the batch sent for enrichment is rising, and the concentrate yield is falling. With decrease in the content of bituminous coal in the coking batch, the strength of the coke is declining. Improving the performance of the coke-production and blast-furnace shops depends on access to coal of satisfactory structure and quality.     

加强焦炉生产管理 提高焦炭机械强度

炼焦生产工艺管理如加热制度、装平煤操作会影响焦炭的机械强度,只有通过不断加强炼焦的生产管理才能提高焦炭质量。     

Ensuring stable quality of blast-furnace coke

Blast-furnace performance is dependent on the coke quality and, above all, its stability. The stability of coke properties is ensured by effective homogenization of the coal components on storage and on blending crushed coal to form the coking batch.     

捣固焦生产技术研究

本文通过对顶装炼焦与捣固炼焦生产技术的分析、比较,认为捣固炼焦能大幅度降低焦炭生产成本,增加企业利润。捣固焦炉是焦化行业发展的主要方向之一,大型化是炼焦技术发展的总趋势。     

Plastic wastes, lube oils and carbochemical products as secondary feedstocks for blast-furnace coke production

Two plastic wastes (polyolefin-enriched and multicomponent), two lube oils (paraffinic and synthetic) and one coal-tar were assessed as individual and combined additives to coal blends for the production of blast furnace coke. The effects of adding 2 wt.% of these additives or their mixtures (50:50 w/w) on the coking capacity of coal, coking pressure and coke quality parameters were investigated. It was found that the two plastic wastes reduce fluidity, whereas the addition of oils and tar helps to partially restore the fluidity of the coal-plastic blend. From the co-carbonization of the coking blend with the different wastes in a movable wall oven of over 15 kg capacity, it was deduced that polyolefins have a detrimental effect on coking pressure. The addition of oils and tar to the coal-plastic blend has different modifying effects. Whereas paraffinic oil eliminated the high coking pressure caused by the polyolefins, polyol-ester oil had a weak reducing effect unlike coal-tar which had a strong enhancing effect. The compatibility of the oils/tar with plastics and coal and the beneficial influence of these combinations on coking pressure is discussed in relation to the miscibility of the plastic and the oily and bituminous additives, and the amount and composition of the volatile matter evolved from each additive during pyrolysis as evaluated by thermal analysis. Furthermore, it was found that coke reactivity towards CO₂ (CRI) and coke strength after reaction with CO₂ (CSR) are heavily dependent on the composition of the plastic waste, with polystyrene (PS) and polyethylene terephthalate (PET) having a clear negative effect. The porosity of the cokes obtained from blends containing plastic wastes is always higher, but the pores are smaller in size.     

焦炭强度指标间关系探讨

焦炭的冷态强度测定周期较短?成本低廉,而热态性能测定周期相对较长?成本昂贵。因此,利用焦炭冷态强度预测热态性能,不但对指导焦化生产具有一定的意义,而且利用各强度指标间的关系可以检验实际测量数据是否存在异常值。     

Assessing coke on the basis of the yield of volatiles

Existing methods of assessing coke in production conditions are analyzed. Significant deficiencies are noted in the gravimetric method of determining the yield of volatiles and in methods of determining the temperature of the coke leaving the coking chamber. Assessment of coke on the basis of a modified method of determining the yield of volatiles (by volume) at 1150°C is proposed. In the coke shops at PAO Zaporozhkoks, samples of industrial coke are assessed by the proposed method. A close correlation is found between the yield of volatiles (by volume) and two important coking characteristics: the final temperature and the coking rate. Determination of the yield of volatiles by volume is currently used in the central laboratory at PAO Zaporozhkoks in continually assessing the coke produced and correcting the coking temperature.     

延迟焦化装置长周期运行的措施及设想

焦化炉是延迟焦化装置的核心设备 ,认为引起焦化炉管结焦的主要原因有进料性质、辐射管表面热强度、辐射炉管排列方式、炉出口温度控制、炉管介质流速及流动状态等。根据延迟焦化原理 ,合理设计 ,精心操作 ,可减缓焦炭生成速度 ,使焦化炉的连续开工周期得以延长。针对焦化装置普遍存在的炉管结焦、大油气线结焦、分馏塔底结焦等问题 ,在生产中摸索了一些经验 ,取得了良好的效果     

利用气煤和焦粉制备优质铸造焦的研究

针对中国主焦煤资源短缺而气煤储量相对丰富的资源特点，采用气煤为主焦化煤种，配用焦粉做瘦化剂，并添加一定量的沥青作粘结剂，通过系列配煤方案制备铸造型焦，获得可制备一级铸造焦的优化配煤方案为45：50：5。实验结果表明，随着气煤和沥青配入量减少，焦炭的M40提高，气孔率Ps降低，焦炭显微结构越趋向于致密化。在实验配比条件下，沥青添加量降低对于焦炭强度提高的影响较气煤显著；而气煤配比减少对于焦炭气孔率降低的影响较沥青显著。     

Oil-cum-gas-fired experimental coke oven developed at CFRI and the correlation studies of its coke with commercial oven coke

Assessment of the coking behaviour of coals and blends by conducting coking tests in experimental coke ovens still continues to be the most reliable method and is extensively used all over the world. The oil-cum-gas fired experimental coke oven developed at CFRI has a coal charging capacity of 1100 kg and simulates industrial carbonising conditions. The oven is capable of intermittent operation and can be brought up to working temperature within 36 hours.Correlation studies of coke quality were carried out by conducting a series of coking tests on the same blend, carbonised under similar conditions in the CFRI experimental coke oven and the commercial coke ovens of Bokaro Steel Plant. The study has revealed that the physical strength of the CFRI oven coke compares favourably with the Bokaro oven coke. M₄₀ and M₁₀ indices of the commercial oven coke can be predicted fairly accurately from the results of CFRI oven coke.T-tests performed on the shatter results showed that at 5% probability level there was no significant variation between the shatter indices of both cokes. The quality of the gas produced from the CFRI test oven was very similar to that of the gas produced from the Bokaro ovens.     

Adding coke dust to coal batch

The granulometric composition of coke dust from the dry-slaking machine is determined. The influence of additions of 3−7% coke dust on the quality of industrial coking batch and the coke obtained by box coking is estimated. Adding 1% coke dust to coking batch does not markedly change the coke quality. Industrial equipment for the supply of dry-slaking dust to the batch is described.     

常规焦炉上的完全型煤炼焦

简单介绍了型煤炼焦技术在国内外的发展情况。分析了型煤炼焦的优点,包括提高了非主流炼焦煤种的利用量;在降低入炉煤水分的同时,缩短了炼焦周期,降低了焦粉产率。但型煤炼焦也存在诸多问题,主要包括炉型小且适应性差,炼焦过程中对环境的污染严重,产出的炼焦产品质量不稳定。为了解决上述问题,研究了常规焦炉上的完全型煤炼焦技术。介绍了该工艺的流程,重点分析了其经济意义与技术可行性。结果表明:完全型煤炼焦可以提高不粘煤的配入比例,从而直接提高焦炭产量。在降低入炉煤成本的情况下,提高了焦炭品质。