Industrial Coke Oven Research Articles

Study on the Influence of Industrial Coke Oven Size on the Quality of Metallurgical Coke

The large-scale coke oven is a developing trend in coking technology, and the influence of the industrial coke oven size on the quality of metallurgical coke needs to be revealed. Under the same raw coals and blending ratios, metallurgical cokes were obtained from top-loading coke ovens with carbonization chamber heights of 6 and 7 m, respectively. The macroscopic quality and microstructure of the refined metallurgical cokes were comprehensively tested. The results showed that the conventional cold and thermal strength indexes of Coke-7m were better than those of Coke-6m. The comprehensive thermal strength at multiple temperatures further showed that the thermal strength advantage of Coke-7m was mainly manifested at low temperatures (1050 and 1100 °C) or a high temperature (1300 °C), where the solution-loss reaction mode of coke tended to be the “uniform reaction model” or “unreacted core model”. At medium temperatures, the solution-loss reaction mode tended to be the “gradient reaction model”, which had a greater destructive effect on the thermal strength of coke. At this time, the thermal strengths of the two cokes were close. Microstructure characterization revealed that industrial coke oven size mainly affected the carbon structure of coke but had little effect on pore structure. The advantage of Coke-7m regarding carbon structure is an important reason for its superior macroscopic quality compared to Coke-6m.

Cooperative treatment and resource utilization of municipal solid waste by industrial coke ovens: Effects of doping ratio and management

For the collaborative treatment and resource utilization of an industrial coke oven on municipal solid waste (MSW), this study used MSW to prepare refuse-derived fuel (RDF). The influence of different mix ratio between RDF and coal on coking products was considered, and technical and economic analyses were conducted. The results showed that under the low mixture ratio (3%), the pyrolytic carbon obtained basically met the class III standard of metallurgical carbon. In the experiment of medium mixture ratio (25%, 30%, 35%), the product contained a certain amount of calorific value, lower than that of the metallurgical coke. It might be that the ash content increased, and such product can be used for civil coke or chemical coke. When the mixture ratio was 100%, the calorific value of pyrolysis carbon was 7.53 MJ/kg, representing 25.7% of the calorific value of ordinary coke. The gas production rate of the discharged gas was 0.35, and the calorific value is 14.0 MJ/kg, reaching 73.6% of the coke oven gas. Under the condition of no coal input, the MSW was converted into usable energy. The results demonstrated that coke oven pyrolysis with 100% RDF addition is the most feasible way to recycle resources and energy.

Modeling of an integrated H2S/NH3 scrubber and regeneration columns for coke oven gas purification

A model of an industrial coke oven gas absorption/stripping process for hydrogen sulfide and ammonia removal is developed. Three scrubbing liquids, weak and strong ammoniacal water produced by the strippers and sodium hydroxide solution, are used in the scrubber. Rate-based modeling is used for both the scrubber and the strippers. The model can accurately predict hydrogen sulfide and ammonia concentration in vapor sampled from multiple locations in the scrubber. The effects of the scrubbing liquid flow rates on the scrubbing efficiency is studied with a sensitivity analysis. It is found that increasing the flow rate of strong ammoniacal water can improve the hydrogen sulfide scrubbing efficiency. Increasing the flow rate of weak ammoniacal water can enhance both hydrogen sulfide and ammonia scrubbing efficiency. However, the pH of the wastewater produced by the process also increases, which may adversely affect the wastewater treatment process. Using more sodium hydroxide solution can effectively enhance hydrogen sulfide scrubbing efficiency, but its effect on the pH of the wastewater is profound. These results can provide guidance for improved operation of this process and similar processes.

A Predictive Model for Coal Coking Based on Product Yield and Energy Balance

A series of experimental coal pyrolysis studies were conducted to define the parameters of a kinetic model to enable complete mass and energy balances by identifying basic process products. The developed model determines the chemical enthalpy of pyrolytic reactions, making it possible to determine the share of exothermic conversions in the coking process. To validate the model, a series of experimental pyrolysis tests of coking coals used in the coke plant and their blends were conducted, including TGA, retort, and industrial coke oven scale. Despite significant differences in the chemical composition of various coal types, element balancing allowed detection of the difference in product composition and the heat effects of the chemical conversion of such a complex substance as coal. Analysis of the heat effects of pyrolytic coal decomposition indicates substantial variability. In the first coking period, there are endothermic reactions; in the second, exothermic reactions occur. Average heat effect of the pyrolytic reaction for whole coking period is exothermic and, depending on the coal type, ranges from −5 to −50 kJ/kg. The model herein can be used to analyze many other pyrolytic processes because it also takes into account the heating rate.

Evaporation experiment and numerical simulation study of desulfurization wastewater in high-temperature raw gas

This study adopts Fluent software to perform a numerical simulation on the evaporation of desulfurization wastewater, which is based on the experimental study of spraying desulfurization wastewater to the high-temperature raw gas (around 750 °C) inside the single riser of industrial coke oven. Regarding to the results, a further optimization was applied to the core-part nozzle structures of spraying wastewater in the experimental plant. The results indicated that the farthest distance of the droplets movement calculated by the modified formula We = f(T) was 0.051 m at 800 °C, which is more consistent with the experiment. When the flow rate of raw gas was increased from 0 m3/h to 700 m3/h, the dispersion degree of droplet particle trajectory was enlarged from range −0.181−0.174 m to −0.308−0.246 m on the x-axis, and the time that the droplet particles reached the gas flow rate accelerated from 0.007 s to 0.02 s. The relationship between the riser’s average temperatures before and after spraying desulfurization wastewater was T = 568.49In(T0) − 3151.9. It was consistent with the actual value. Within the coking time of 20 h, the average temperature of the riser after evaporation was 620.44 °C and the average evaporation time was 0.0025 s, when the desulfurization wastewater was sprayed at 3 m away from the water seal of the riser. The optimized injection system according to the simulation results has improved the treatment effect of the wastewater in the experimental plant.

Environmental impact of polymer-waste disposal

The laboratory carbonization of well-known polymers to 850°C is studied, in order to determine the benzo[a]pyrene emissions. In carbonization, the exhaust gases from all the polymers contain benzo[a]pyrene in levels far exceeding workplace air standards. The levels are higher for carbon-chain polymers than for heterochain polymers. The utilization of polymer wastes with the coal batch in coke ovens is investigated. It is found that the yield of gas and its content of benzo[a]pyrene are several times higher than for industrial coke ovens. This means that, in the industrial coking of coal batch with added carbon-chain polymers, elevated expansion pressure should be expected in the coke oven, along with increased atmospheric emissions of benzo[a]pyrene.

One-dimensional model of heat-recovery, non-recovery coke ovens. Part III: Upper-oven, down-comers and sole-flues

This paper is Part III of the series (Buczynski et al., 2016) concerning the mathematical modeling of HR/NR coke ovens and it formulates one-dimensional models describing combustion and heat transfer in the space above coking-bed (upper-oven), in down-comers and in sole-flues. The space above a coking-bed is modeled using the well-stirred reactor concept while other oven branches are modeled using the long plug-flow furnace concept. The numerical simulations indicate a slow mixing-controlled combustion of gaseous mixtures in the down-comers and in the sole-flue channels. Such a behavior is typical for industrial coke ovens. Thermal radiation is the main mechanism of heat transfer and it accounts for up to 90% of the overall heat transfer rate. The mathematical model calculates also the refractory temperatures and in some sole-flue branches they approach too high values which may render oven damages.

Effects of rapid thermal alteration on coal: Geochemical and petrographic signatures in the Springfield (No. 5) Coal, Illinois Basin

Igneous intrusion into a coal bed can change the geochemical and petrographic properties of the coal including vitrinite reflectance, maceral petrographic composition, optical texture, mineralogy, stable isotope composition, trace element composition, and bulk geochemistry. The intent of this study was to evaluate petrographic and geochemical changes in an intruded coal and compare them to trends seen in coals altered by normal burial maturation, thereby evaluating whether or not the intruded coals followed a different maturation pathway. The current study reports petrographic, bulk geochemical (proximate, ultimate), Leco total organic carbon (TOC), and Rock-Eval pyrolysis data for a suite of samples from the Springfield (No. 5) Coal (Pennsylvanian, Desmoinesian) in the southern part of the Illinois Basin where the coal had been intruded by a Permian-age peridotite dike.Petrographic analysis shows an increase in vitrinite reflectance (Rm) from background levels of 0.55–0.63% up to ~4.80%, a loss in ability to differentiate liptinite macerals, formation of isotropic coke and, at the dike/coal contact, development of fine-grained mosaic anisotropic coke texture. Volatile matter (VM) content decreases and fixed carbon (FC) content, ash, and mineral matter (Parr formula) increase approaching the intrusion contact. Carbon increases whereas nitrogen, hydrogen, and oxygen decrease approaching the intrusion. The presence of carbonate minerals (confirmed by X-ray diffraction and petrographic analysis) has a significant impact on proximate and ultimate data. However, even after removal of carbonates, trends for VM vs. Rm, %C vs. Rm, and H vs. C do not follow typical trends associated with normal burial coalification. Approaching the contact, Leco TOC, Rock-Eval free oil content (S1), remaining hydrocarbon potential (S2), CO2 from pyrolysis of the organic matter (S3), and hydrogen (HI) and oxygen (OI) indices decrease whereas thermal maturity (Tmax, °C) increases. S2 vs. Rm and Tmax vs. Rm diverge from the pathways seen in previous studies of coals that have undergone normal burial maturation.Geochemical data from this study suggest that the intruded Springfield (No. 5) Coal may have followed a maturation track that differed from that seen under normal burial maturation, perhaps due to the geologically rapid, high heating event associated with the emplacement of the intrusion. It is also suggested here that the natural coke textures produced by this rapid geological heating may differ from those observed for metallurgical cokes produced under standard industrial coking conditions. Typically, in an industrial coke oven, a coal of this initial rank (Ro=~0.6%) would produce an isotropic coke, rather than the fine-grained circular anisotropic coke seen here. However, as variations in heating rate, duration of heating, maximum temperatures attained, hydrothermal conditions, and pressure are mostly unknown for the intrusive event, it is not unreasonable to suggest that differences in these variables contributed to the higher anisotropy of the coke. Alternatively, the development of this texture may reflect “pre-heating” of the coal during the intrusion event.

Coke Oven Carbon Deposits Growth and Their Burning Off

Burning off is the main method of carbon deposit removal from coke oven chambers. Optimisation of this operation is of a great interest both from the point of view of current production loss reduction and of coke oven plant lifetime extension. In this study the deposits originating from different parts of chambers have been characterised by chemical analysis, optical microscopy, XRD, Raman spectroscopy and mercury porosimetry. This investigation has shown that deposits contain two carbonaceous phases: the char from pyrolysed carry over coal particles and the pyrolytic carbon from raw gas cracking. Furthermore, the monitoring method for carbon deposits growth in coke oven chamber is presented. The statistical analysis of the visual inspection data has been a useful tool in the evaluation of the rate of deposit growth in individual coke oven chambers. The combustion kinetics of carbon deposits were studied by thermogravimetry under non-isothermal conditions with natural air draft and under isothermal conditions at controlled air flow rate. It was found that the reactivity of carbon deposits is in-between metallurgical coke and electrographite reactivity. At the temperatures below 700 degrees C, under laboratory conditions, the combustion rate (on the basis of external surface) is controlled by surface reaction at higher temperature and activation energy is around is 170 kJ/mol. At temperature higher than 700 degrees C combustion is controlled by gas film diffusion. Modelling of combustion in thermobalance experiments and in industrial coke oven chamber was carried out on the basis of measurement of kinetics using commercial CFD software.

99/02948 Investigation of mechanisms leading to coal pressure swelling in industrial coke oven

99/02948 Investigation of mechanisms leading to coal pressure swelling in industrial coke oven

98/01047 Selection criteria for the optimal charging-discharging batch operation of large coke ovens. 3. Determination of bulging pressure in industrial coke ovens: Sheptovitskii, M. S. et al. Koks Khim., 1995, (9), 14–18. (in Russian)

98/01047 Selection criteria for the optimal charging-discharging batch operation of large coke ovens. 3. Determination of bulging pressure in industrial coke ovens: Sheptovitskii, M. S. et al. Koks Khim., 1995, (9), 14–18. (in Russian)

98/00003 Characterization of the swelling behavior of coals in industrial coke ovens

98/00003 Characterization of the swelling behavior of coals in industrial coke ovens

97/03111 Criteria for selection of optimal bonding-discharge series for large coke ovens. 3. Determination of wall pressure in industrial coke ovens. Reply to comments. Method for measurement of wall pressure in industrial coke ovens

97/03111 Criteria for selection of optimal bonding-discharge series for large coke ovens. 3. Determination of wall pressure in industrial coke ovens. Reply to comments. Method for measurement of wall pressure in industrial coke ovens

97/00577 Measurement of coking pressure in industrial coke ovens

97/00577 Measurement of coking pressure in industrial coke ovens

Study of the apparent density in 7 m industrial coke ovens

Study of the apparent density in 7 m industrial coke ovens

Application of the retention index system in the gas chromatographic analysis of industrial coke oven samples containing cyclopentadiene

Application of the retention index system in the gas chromatographic analysis of industrial coke oven samples containing cyclopentadiene