Coking Temperature Research Articles

A novel dual-way inference modeling method for coal coking: Predicting H2 and CH4 concentrations in coke oven gas and inferring optimal reaction conditions

Coal coking is an efficient and environmentally friendly technology for energy utilization that yields various industrial materials. However, the intricate nature of the coal coking reaction poses a challenge for chemical theories to fully capture and derive its reaction process. To address this challenge, a novel dual-way inference modeling method was proposed to simulate the coal coking process. This modeling method not only predicts H2 and CH4 concentrations, but also infers optimal operating conditions based on the desired H2 and CH4 concentrations. In this work, three representative machine learning methods (XGBoost, Random Forest, and ANN) are compared with dual-way inference modeling method, and the key factors affecting H2 and CH4 concentrations are thoroughly explored. The experimental results show that the primary factor influencing CH4 concentration is C, H2 concentration is predominantly affected by fixed carbon, while C plays the most important role for CH4 + H2. The dual-way inference modeling method achieved excellent performance in predicting H2 and CH4 concentrations and operating conditions. In the prediction task of H2, CH4, and H2 + CH4 concentrations, the coefficient of R2 achieved 0.9767, 0.9936, and 0.9851, respectively. The result for predicting coking temperature based on the desired H2 and CH4 concentrations indicate a positive correlation between coking temperature and both H2 and CH4 concentrations. In general, as coking temperature increases, the concentrations of both H2 and CH4 will increase.

CFD-DEM study on the raceway transport phenomena and thermo-chemical behaviors in a three-dimensional blast furnace: Effects of process parameters

An in-depth exploration of the kinetic behaviors of the raceway can provide practical insights for optimizing blast furnace (BF) operations. In this study, the transport phenomena and thermo-chemical behaviors in the raceway of a three-dimensional BF were simulated from particulate scale by using the discrete element method-computational fluid dynamics (DEM-CFD) approach. The effects of process parameters (blast velocity, oxygen concentration, blast temperature, coke size and distribution, tuyere insertion depth, and tuyere inclination) on coke combustion characteristics (mass fraction distributions of gas species and reaction kinetics rate) and thermo-chemical behaviors (particle volume fraction, raceway size, mass loss, and coke temperature) were investigated. Meanwhile, microstructures of coke bed were analyzed, and correlations were established for raceway size prediction. The results indicate that the mass fraction distributions of O2 and CO are similar, both showing balloon-like shapes. The distributions of both the CO2 mass fraction and the kinetic rates of reactions exhibit annular shapes. The raceway size increases or even overlaps with increasing blast velocity/oxygen concentration/PSD standard deviation of coke and decreasing blast temperature/coke size. Too large or too small tuyere insertion depth or tuyere inclination is not conducive to the formation of the raceway. Besides, the mass loss, temperature, and microstructures also vary with the process parameters. RSM model can well predict the raceway depth, width, and height. This study extends the particle-scale model by considering transport phenomena towards the global perspective of a real BF, and the obtained new findings on the complex reacting behaviors in the raceway will provide better insights into the optimization of the BF process.

Effect of High Calcium and High Iron Coal on Ash Fusion Characteristics of Petroleum Coke during Cogasification.

Entrained flow gasification provides a more efficient utilization method for high-sulfur petroleum coke. The operation temperature of the entrained flow gasifier must be above the ash fusion temperature (AFT) of petroleum coke due to the liquid slag discharge. In this work, petroleum coke was blended with high-calcium coal and high-iron coal, respectively, under a reducing atmosphere, and the variations in AFTs were recorded by an ash fusion temperature analyzer. The influence of mineral transformations on the ash fusion characteristics of blended ash was analyzed by X-ray diffraction and FactSage. The results showed that both high calcium coal and high iron coal could efficiently reduce the AFTs of petroleum coke. When the ratio of high calcium coal and high iron coal reached 60 wt %, the corresponding flow temperature (FT) of mixed ash decreased to 1225 and 1312 °C, respectively. With the content of high calcium coal increasing, coulsonite (FeV2O4), vanadium trioxide (V2O3) and nickel (Ni) with high-melting points tended to decrease, causing the decrease of AFT for mixed ash. As high iron coal was added, Ni and V2O3 continuously kept decreasing. In particular, the percentage of FeV2O4 first increased and thereafter decreased with high iron coal above 40 wt %.

Optimization of convection cooling by pressed brick structure and coke conversion rate in coke dry quenching furnace

Segregation of coke temperature and gas flow in Coke Dry Quenching furnace is a crucial issue in coke production, and the pressed brick structure of Coke Dry Quenching furnace plays a significant role in the problem of segregation. In this work, computational fluid dynamics simulation software Ansys Fluent and self-programmed equations were utilized to investigate the fluid flow and heat transfer processes, as well as coke particle combustion behavior, based on the No. 2 Coke Dry Quenching furnace at the Bayuquan coking plant of Ansteel. The focus was on analyzing the impact of gas flow rate and pressed brick structure on the furnace’s flow and temperature fields, as well as assessing the extent of coke particle combustion under different gas flow rates. The simulation involved the use of porous media models, pseudo-fluid models, and non-local thermal equilibrium to simulate the heat transfer processes within the CDQ furnace. The simulation results show that when the coke discharge rate was set at 160 t/h, selecting a circulating gas flow rate of 180,000 m3/h could ensure that the outlet temperature of coke meet the production requirement and reducing energy consumption. Optimizing the pressed brick structure appropriately can clearly improve the segregation in gas flow and temperature within the furnace. This led to a reduction of approximately 0.3 m in the height of coke isotherm line segregation at 500 K, while also lowered the average temperature at the coke outlet. Furthermore, we established the improved random pore model with two new equations to describe the evolution of coke porosity and the molar composition of the ambient gas, and real-time tracking of changes in coke porosity and considered the impact of variable gas concentration on coke conversion rate were provided. These findings offer valuable insights and reference for optimizing operational conditions and coke quality prediction in actual production scenarios.

The concept of axial movement of blast furnaces and temperature distribution on the horizon of air tuyeres

The purpose of the work is to clarify the data on temperature changes on the horizon of the air tuyeres of blast furnaces. The limitations associated with the implementation of the well-known concept of axial movement of blast furnaces in terms of temperature stabilization in the coke nozzle blast furnace are considered. Based on the comparison of the results of studies on the temperature distribution of coke and its fractional composition at level of air tuyeres, it is shown that on blast furnaces equipped with coneless filling devices and coal dust blowing units, the critical zone in the distribution of temperatures and their fluctuations in time is the intermediate zone between "bird's nest" and the center of the furnace. A temporary, but sufficiently long-term decrease in the temperature of coke to 1000 °C in the intermediate zone of modern blast furnaces is not accompanied by the danger of toterman formation, which is facilitated by the existence of an axial coke vent — a kind of heated core of the coke nozzle and sufficient thermal inertia of the furnace. It has been established that the increase in blowing costs affects distribution of coke temperatures on the horizon of air tuyeres in a similar way to the tendency of the hot strength of coke to deteriorate — the temperatures in the intermediate zone of the coke nozzle decrease. It is recommended to take into account the change in the quality of the loaded coke when choosing dimensions of the coke vent in the center of the furnace and the degree of forcing its course by blowing. In the conditions of using pulverized coal fuel, when working on coke of average quality, the most acceptable mode of organization of the radial gas flow is peripheral-axial with an advantage in the development of axial over peripheral. Despite some conventionality of the examples discussed in the article, it can be argued that a long axial stroke without stroke disturbances can be realized only if the intensity of the peripheral gas flow is maintained for specific conditions. That is, in an ideal form, axial movement of blast furnace melting is practically impossible.

Раціональні технологічні засади отримання коксу із заданими показниками питомого електричного опору

DOI: 10.31081/1681-309X-2024-0-1-8-15 Specialty 161. U.D.C. 661.66.2:537.311/.312 RATIONAL TECHNOLOGICAL BASES OF PRODUCTION OF COKE WITH SPECIFIED ELECTRICAL RESISTIVITY © I.V. Shulga, Ph.D. in Technical Sciences, O.V. Sytnyk, Ph.D. in Technical Sciences (State Enterprise “Ukrainian State Research Institute for Carbochemistry (UKHIN)”, 7 Vesnina str., Kharkiv, 61023, Ukraine), O.I. Zelenskii, Ph.D. in Technical Sciences, V.V. Vladymirenko (National Technical University "Kharkiv Polytechnic Institute", 2, Kyrpychova str., Kharkiv, 61002, Ukraine) The article is devoted to the practically important issue of obtaining coke with a specific electrical resistance of no more than 0.1 Ohm∙cm for the needs of blast furnace production. Achievement of this indicator should occur simultaneously with the improvement of the entire range of properties of blast furnace coke. It is noted that the concept of production of blast furnace coke of improved quality consists of the formation of a rational raw material base, ensuring proper coking technology and post-furnace coke treatment. It has been shown that the production of high-quality blast furnace coke with low resistivity requires: high sinterability and coking capacity of the charge based on highly sinterable coals; coking pressure of the coal charge not exceeding 7 kPa; coking speed not exceeding 24 mm/hour; final coking temperature of 1050-1100 °C; maximum temperature level in the heating system not exceeding 1410 °C. It is confirmed that in order to obtain a low electrical resistivity, it is necessary to produce coke with the most ordered anisotropic structure. It is shown that the resistivity of coke naturally changes when used in blast furnace production: the destruction of lumps leads to the formation of fragments of different sizes. At the same time, coarser fragments have lower resistivity values, and smaller ones, characterized by an increased concentration of structural defects that are the centers of crack formation, have a higher resistivity. After gasification with carbon dioxide, the number of structural defects increases in grains of any size due to the weakening of the surface due to chemical interaction, so the resistivity of coke increases and becomes almost equal for both coarser and finer grains. Keywords: hard coal coke, blast furnace production, resistivity, vertical temperature, final coking temperature, coke gasification. Corresponding author I.V. Shulga, e-mail: ko@ukhin.org.ua

Ефективність використання коксу із заданими значеннями питомого електричного опору

DOI: 10.31081/1681-309X-2024-0-2-28-32 Specialty161, 051. U.D.C. 661.66.2:537.311/.312 EFFICIENCY OF COKE UTILISATION WITH SPECIFIED VALUES OF ELECTRICAL RESISTIVITY © V.V. Vladymirenko, N.M. Dyakova (National Technical University "Kharkiv Polytechnic Institute", 2, Kyrpychova str., Kharkiv, 61002, Ukraine), I.V. Shulga, Ph.D. in Technical Sciences, (State Enterprise “Ukrainian State Research Institute for Carbochemistry (UKHIN)”, 7 Vesnina str., Kharkiv, 61023, Ukraine) The article shows that ensuring the specified values of coke resistivity for different directions of its use allows achieving a positive effect in metallurgical production. It is noted that the resistivity of coke for modern blast furnaces using pulverised coal should be minimal. This is ensured by the proper final coking temperature, which makes it possible to obtain coke with the required level of readiness – the final temperature should be at least 1100 оС. This reduces not only the specific electrical resistance of coke, but also its reactivity. The post-reaction strength of the coke is also significantly increased. This makes it possible to reduce coke consumption for pig iron production and increase the productivity of blast furnaces. As a result, it can be achieved the generation of an additional profit of UAH 377.20 per ton of coke. The resistivity of ferroalloy coke, unlike blast furnace coke, should be as high as possible, which will increase the amount of heat generated in the electric circuit of ferroalloy furnaces and used for endothermic reduction reactions. Therefore, lower coke readiness and lower final coking temperatures are sufficient to produce ferroalloy coke. The use of such coke makes it possible to increase the productivity of electric furnaces for smelting ferroalloys and reduce the consumption of raw materials and electricity. According to the results presented in this article, the additional profit is 4741.37 UAH per ton of coke. The weighted average efficiency of the use of coke with given values of resistivity in the national economy, determined by the volume of coke use in various industries, is 464.48 UAH per ton of coke. Keywords: coal coke, electrical resistivity, post-reaction strength, blast furnace production, ferroalloy production, economic efficiency. Corresponding author I.V. Shulga, e-mail: ko@ukhin.org.ua

The Relationship between Specific Electrical Resistance and the Readiness of Coal Coke

The readiness of coal coke is a necessary condition for ensuring its high quality, which ultimately depends on the degree of orderliness of the macromolecular structure in the form of graphite-like blocks. Coke then acquires semiconductor properties. According to the zone theory of solid-state physics, the dependence of the specific electrical resistance of coke on the final coking temperature has an exponential form. The pre-exponential factor characterizes the properties of the original coal, including its caking ability, the content of mineral impurities, and their ability to form free current carriers (electrons or holes). The coefficient in the exponent indicates the rate of decrease of the logarithm of resistance with increasing temperature. These two quantities can be determined experimentally. For each blend composition, they determine the final coking temperature required to form the appropriate coke readiness, taking into account its intended use.

Effect of coke reactivity on softening-melting and dripping behaviors of sinter

ABSTRACT The use of high reactivity coke in blast furnaces is an important direction for low-carbon development. In this study, we investigated the effect of coke reactivity on the softening-melting behaviors of the sinter. The results show that the gasification temperature of coke decreased with increasing coke reactivity. With increasing coke reactivity from 24.75% to 45.11%, the initial melting temperature rose from 1294°C to 1312°C, the dripping temperature dropped from 1522°C to 1507°C and the melting region decreased from 228°C to 195°C, respectively. The cohesive zone shifted downward and the thickness narrowed. The permeability index and highest differential pressure dropped from 1219.67 KPa·°C to 607.61 KPa·°C and from 7.0962 KPa to 4.8523 KPa, respectively. Coke with high reactivity can improve the gas permeability of burden. The gas utilization ratio in the softening-melting and dripping processes of the sinter raised by about 2% with increasing coke reactivity.

Numerical and experimental study on temperature and heat transfer characteristics in centrifugal compressor diffuser

Lubrication oil aerosol deposit and coking in the compressor diffuser is a typical issue for the high power density internal combustion engine (ICE) using the closed crankcase ventilation (CCV) system. The aerosol coking significantly negatively influences the compressor's performance, leading to a penalty on ICE performance. The severity of the coking effect is highly dependent on temperature. In order to predict occurrence of coking and to clarify how to avoid aerosol coking in the compressor, the temperature distribution and heat transfer characteristics are investigated in this study. An experimental investigation on the diffuser temperature distribution at shroud side was carried out first. Numerical simulations that consider the heat transfer between the solid domain and the fluid domain are conducted, aiming at analyzing the temperature distribution of inner surface. The detailed simulation model of small high-pressure-ratio compressor for predicting coking risk is established. Furthermore, the simulation model is validated by the experimental results. The results indicate that the shroud side of the diffuser sees the highest temperature level in the diffuser. Under typical operation conditions, the temperature at the diffuser wall exceeds the threshold coking temperature of lubrication oil aerosol, this location most likely to have severe coking issues. Thus, the location of the shroud plate is the primary region that needs to be cooled down to mitigate the coking issue. Meanwhile, the intensity of heat transfer between the fluid and solid domain in the diffuser region degrades significantly along the flow direction and sees an 80% drop from diffuser inlet to outlet, indicating the requirements for further enhancement of heat transfer in diffuser shroud side along streamwise.

ВИКОРИСТАННЯ ПОКАЗНИКА ПИТОМОГО ЕЛЕКТРИЧНОГО ОПОРУ ДЛЯ ОЦІНКИ ГОТОВНОСТІ КОКСУ (огляд)

The article provides a review of scientific information on the use of the resistivity index to assess the readiness of coke, which is ultimately determined by the degree of orderliness of the macromolecular structure in the form of graphite-like blocks. In this process, coke acquires semiconductor properties and its resistivity decreases. Coke for modern blast furnaces using pulverized coal should have a minimum resistivity of 0.1 ohm∙cm or less. For other applications (in particular, in ferroalloy production), the resistivity of coke should be higher. It has been shown that the most acceptable method for an objective assessment of the resistivity is the two-probe method of measuring the resistivity of coke powder, a representative sample for which is obtained with minimal time and labor. The main factor that affects the resistivity of the coke produced is the final coking temperature, i.e. this characteristic is indeed an objective indicator of coke readiness. With the increase of the final coking temperature, the supramolecular structure of coke is streamlined, which in a certain way approaches the structure of graphite, and this leads to a decrease in the resistivity of coke. It is concluded that it is necessary to theoretically analyze the processes that lead to changes in the electrical conductivity of coke. This will make it possible to reasonably determine the nature of the dependence of the coke resistivity on the final coking temperature. Determination of the numerical parameters of this dependence, in turn, will make it possible to establish a rational level of the final temperature for coke production for various applications, which is of great practical importance. Keywords:hard coal coke, electrical resistivity, coke readiness, blast furnace coke, ferroalloy coke. Corresponding author І.V. Shulga, e-mail: ko@ukhin.org.ua

Використання показника питомого електричного опору для оцінки готовності коксу (огляд).

The article provides a review of scientific information on the use of the resistivity index to assess the readiness of coke, which is ultimately determined by the degree of orderliness of the macromolecular structure in the form of graphite-like blocks. In this process, coke acquires semiconductor properties and its resistivity decreases. Coke for modern blast furnaces using pulverized coal should have a minimum resistivity of 0.1 ohm∙cm or less. For other applications (in particular, in ferroalloy production), the resistivity of coke should be higher. It has been shown that the most acceptable method for an objective assessment of the resistivity is the two-probe method of measuring the resistivity of coke powder, a representative sample for which is obtained with minimal time and labor. The main factor that affects the resistivity of the coke produced is the final coking temperature, i.e. this characteristic is indeed an objective indicator of coke readiness. With the increase of the final coking temperature, the supramolecular structure of coke is streamlined, which in a certain way approaches the structure of graphite, and this leads to a decrease in the resistivity of coke. It is concluded that it is necessary to theoretically analyze the processes that lead to changes in the electrical conductivity of coke. This will make it possible to reasonably determine the nature of the dependence of the coke resistivity on the final coking temperature. Determination of the numerical parameters of this dependence, in turn, will make it possible to establish a rational level of the final temperature for coke production for various applications, which is of great practical importance. Keywords:hard coal coke, electrical resistivity, coke readiness, blast furnace coke, ferroalloy coke. Corresponding author І.V. Shulga, e-mail: ko@ukhin.org.ua

Експериментальне дослідження залежності питомого електричного опору коксу від кінцевої температури

The dependence of the resistivity on the final coking temperature was studied on cokes obtained from the charge of one of the leading coke plants in Ukraine in a laboratory furnace designed by SE "UKHIN" with electric heating. The increase in the final temperature naturally contributes to an increase in coke readiness and the degree of orderliness of its structure. This is manifested in an increase in coke strength (increased resistance to grinding forces and post-reaction strength, reduced abrasion), increased coke density and porosity, reduced reactivity, volatile substance yield and specific electrical resistance. The increase in the final temperature contributes to the deepening of thermochemical polycondensation processes of coke formation, which causes the loss of additional low-molecular weight products, resulting in a slight decrease in the yield of gross coke and its sulphur content with a simultaneous increase in ash content. The previously theoretically substantiated hypothesis about the exponential nature of the dependence of the decrease in the specific electric coke with an increase in the final coking temperature was experimentally confirmed. Processing of the obtained experimental data made it possible to determine the numerical characteristics of this dependence, which makes it possible to determine the rational level of final coking temperatures when producing coke for various applications. In particular, to produce coke with a resistivity not exceeding 0.1 ohm∙cm, the final coking temperature should not be less than 957 oC. This is in line with the practice of coke production. To produce blast furnace coke with a lower resistivity, a higher temperature is required, while to produce ferroalloy coke with a higher resistivity, on the contrary, a lower temperature level is sufficient. Keywords: coal coke, electrical resistivity, final coking temperature, coke readiness, blast furnace coke, ferroalloy coke. Corresponding author I.V. Shulga, e-mail: ko@ukhin.org.ua

Petroleum coking additive - raw material component for metallurgical coke production. Part 2. Experimental studies of obtaining a petroleum coking additive

Petroleum coke is a potential partial replacement of coking coals (being in short supply) in manufacture of metallurgical coke; in Russia and other CIS countries it was entitled as petroleum coking additive (PCA), petroleum coke with output of volatile substances within the range 15-25 %. The second part of the work describes the results of conducted experimental researches in the field of manufacture of petroleum coke additive on the example of use of two kinds of sulfuric petroleum residues of “KINEF” JSC as raw materials: residue of atmospheric distillation and mixture of residues of vacuum distillation and visbreaking. The research was conducted for two temperature procedures within the ranges 455-465 and 475-485 °С. Eight samples of carbon material were obtained as a result of conversion, and influence of input parameters of the coking process on composition and physical-chemical properties of obtained carbon materials was established. Based on content of volatile substances in petroleum coke additive and its group chemical composition, which was determined via extraction method (content of α-, β- and γ-fractions) and via infrared Fourier spectroscopy, assessment and ranging of the eight obtained PCA samples were carried out by their sintering susceptibility. Interpretation of infrared spectra of obtained PCA samples was conducted via comparison with infrared spectra of coking coal, which have identical absorption stripes. Relation between PCA sintering ability and procedure parameters of the coking process was revealed. It was determined that technological process occurring at the less coking temperature 455-465 °С provides high quality PCA forming, otherwise the procedure with higher temperature (475-485 °С). This work was carried out as part of the State Assignment 0792-2020-0010 “Development of scientific foundations of innovative technologies for processing heavy hydrocarbon raw materials into environmentally friendly motor fuels and new carbon materials with controlled macro- and microstructural organization of mesophase”.

Enhanced gasification effect from discharges and the formation of centimeter-scale plasma during microwave combustion of coke

Microwave technology has been demonstrated as a promising candidate for utilizing fossil fuel in a carbon-efficient manner to ensure energy supply security during the transition to the future green energy economy. Microwave plasma enhancement on gas fuel combustion has been demonstrated, which is attributed to the production of reactive radicals and fuel cracking. However, for solid fuels with low volatilities and ignition and combustion efficiency problems, such as coke; it is still unknown whether the discharge plasma can assist in destroying its aromatic structure, thereby producing extra combustible gases. This process may be a common concern associated with various gas–solid heterogeneous reactions using coal as a reactant. In this study, a centimeter-sized plasma was generated during the combustion of coke under microwave radiation, which significantly promoted the flame burning. Two main factors accounting for the formation of centimeter-scale plasma are discussed: the carbonization temperature and particle size of coke. Additionally, the correlation between CO production and microwave discharge was also examined. Finally, the synergistic promotion mechanism of flame combustion and microwave discharge is proposed. This paper provides new insights into the microwave enhancement mechanism in gas–solid heterogeneous reactions.

Formation and Combustion Heat Release of Naphthenic-Based Crude Oil Cokes at Different Reaction Temperatures.

Petroleum cokes prepared from naphthenic crude oil differ significantly in terms of the oxygen content and hydrogen/carbon (H/C) ratio, which mainly depend on the different coking temperatures. Thermogravimetric-differential scanning calorimetry was applied to study the heat release and combustion weight loss of petroleum cokes prepared at 350 and 500 °C, respectively. The effect of different coke formation temperatures on the combustion properties of the coke formed during air injection in situ combustion (ISC) was also investigated. The results showed that the petroleum coke formed under oxygen exhibited an H/C ratio of 0.895 and an O/C ratio of 0.109 at 350 °C and an H/C ratio of 0.395 and an O/C ratio of 0.054 at 500 °C. As the temperature rises, the hydrogen atoms on the petroleum coke molecules intensify to separate and form water molecules and thus giving off heat. It can be further inferred that under the combustion temperature of air injection ISC, the coke at 350 °C can release more heat in the lower combustion temperature range, and the combustion weight loss is faster; however, the formation temperature continues to rise due to combustion at 500 °C, coke begins to release massive heat, and the combustion weight loss is as high as 97.95%. The combustion residuals of both temperature cokes and the residual solid content of the formation after combustion in porous media are both little, which can be used as fire flooding fuels at different formation temperatures to provide heat energy for oil displacement.

Metallurgical Coke Production with Biomass Additives: Study of Biocoke Properties for Blast Furnace and Submerged Arc Furnace Purposes.

Biocoke has the potential to reduce the fossil-based materials in metallurgical processes, along with mitigating anthropogenic CO2- and greenhouse gas (GHG) emissions. Reducing those emissions is possible by using bio-based carbon, which is CO2-neutral, as a partial replacement of fossil carbon. In this paper, the effect of adding 5, 10, 15, 30, and 45 wt.% biomass pellets on the reactivity, the physicomechanical, and electrical properties of biocoke was established to assess the possibility of using it as a fuel and reducing agent for a blast furnace (BF) or as a carbon source in a submerged arc furnace (SAF). Biocoke was obtained under laboratory conditions at final coking temperatures of 950 or 1100 °C. Research results indicate that for BF purposes, 5 wt.% biomass additives are the maximum as the reactivity increases and the strength after reaction with CO2 decreases. On the other hand, biocoke’s physicomechanical and electrical properties, obtained at a carbonization temperature of 950 °C, can be considered a promising option for the SAF.

Metallurgical Coke Combustion with Different Reactivity under Nonisothermal Conditions: A Kinetic Study.

The combustion characteristics and kinetics of high- and low-reactivity metallurgical cokes in an air atmosphere were studied by thermogravimetric instrument. The Coats–Redfern, FWO, and Vyazovkin integral methods were used to analyze the kinetics of the cokes, and the kinetic parameters of high- and low-reactivity metallurgical cokes were compared. The results show that the heating rate affected the comprehensive combustion index and combustion reaction temperature range of the cokes. The ignition temperature, burnout temperature, combustion characteristics, and maximum weight-loss rate of low-reactivity coke (L-Coke) were better than high-reactivity coke (H-Coke). Low-reactivity coke had better thermal stability and combustion characteristics. At the same time, it was calculated via three kinetic analysis methods that the combustion activation energy gradually decreased with the progress of the reaction. The coke combustion activation energy calculated by the Coats–Redfern method was larger than the coke combustion activation energy calculated by the FWO and Vyazovkin methods, but the laws were consistent. The activation energy of L-Coke was about 4~8 kJ/mol more than that of H-Coke.

Particle-scale study of coke combustion in the raceway of an ironmaking blast furnace

The raceway is a zone of considerable significance in a blast furnace (BF) because it supplies energy and reducing agents that ensure successful and stable BF operation. Recently, experimental and numerical studies of BF have been widely conducted to examine the inner multiphase flow transport phenomena; however, the study of reacting flows at the particle level in BF is limited. In this study, a multiscale method that couples computational fluid dynamics (CFD) with discrete element method (DEM) is employed to examine the dynamic evolution of the raceway and inner thermo-chemical behaviours in a BF. Raceway evolution and formation, microscale characteristics, and coke temperature and combustion are comprehensively explored and analysed under various operating conditions. The predicted results show that the distributions of coke temperature, carbon loss, and diameter variation are consistent. More burning coke particles occurs in the vicinity of the region next to the tuyere, where there is a stronger high-temperature circular gas flow than in other regions. The increase in oxygen concentration indirectly increased the carbon monoxide concentration, but changes in the inlet gas temperature and flow rate yielded no effect on the carbon monoxide level in the studied ranges. These new perceptions of the complicated reacting flows inside the raceway area are beneficial for the fundamental understanding of energy utilisation and process optimisation.

Nickel Catalyst with Atomically-Thin Meshed Coating Fabricated with ALD for Improved Durability in Dry Reforming of Methane

Recent advances in natural gas recovery and applications have drawn much attention to the dry reforming of methane (DRM) with carbon dioxide (CO2). While nickel (Ni) nanoparticles are attractive catalysts for DRM reactions in terms of activity and cost, its practical application is plagued by the quick deactivation in the catalytic environment. In this talk, atomically thin meshed-like Co coating catalytic structure is designed and fabricated to decorate Ni nanoparticles via atomic layer deposition. The coating structure improve the catalytic activity and effectively eliminates carbon deposition for the DRM reaction. Optimized catalytic performance is achieved by fine tuning the density of Co coating on nickel particles. The meshed coating structures partition the Ni surface to prevent continuous carbon nanotubes network formation. The Co component helps stabilizing the metallic phase of Ni in the DRM reaction. The Co-Ni interfaces created are beneficial for reducing carbon intermediates CHx formation and accelerate carbon removal. The amount of carbon formation can be reduced to 2.9%, which is a significant improvement (reduction over 2 to 6 times) compared with a series of state-of-the-art research reports (8%-23%) on Ni-based catalysts in the severe coking temperature range (around 650 ºC). The Co coating layer provides physical confinement and also improves the thermal stability of Ni nanoparticles from sintering and agglomeration up to 850 ºC. The strategies of selective ALD have demonstrated unique advantages to design and fabricate the catalysts in atomic scale and provided insights to understand the structure–activity relationship in a more direct way.