Coal Fluidity Research Articles

Ash Fluidity and Regulation Mechanism of Iron-Rich Low-Rank Coal in High-Temperature Gasification Process

ABSTRACT To realize the high-efficiency utilization of iron-rich coal, it is necessary to conduct research on ash flow characteristics and regulatory mechanisms. The ash flow test was carried out, and we introduced additives such as Huajin red mud (HJ), pipe scale (GDG), diatomite (GZT), and Naomaohu coal (NMH). The results revealed that the elevated Fe2O3 content triggers the formation of metallic iron, leading to poor high-temperature fluidity. NMH and HJ additives have the ability to depolymerize SiO2 and Al2O3 structures. This generates higher contents of anorthite and sodium nepheline. The inclusion of GDG ash promoted the formation of cordierite and forsterite, contributing to improved slag flow. Caution is warranted when using a higher proportion of GDG ash additive, as excessive MgO can combine with Al2O3 to form a high-melting-point spinel mineral. GZT ash leads to an increase in quartz content. During cooling, mullite preferentially precipitates from the liquid phase, further reducing high-temperature fluidity.

表面張力に基づく石炭配合技術の効果的利用法― 配合炭の流動性影響 ―

表面張力に基づく石炭配合技術の効果的利用法― 配合炭の流動性影響 ―

Effective Utilization Method for Surface Tension Based Coal Blending Technique -Effect of Coal Fluidity-

Effective Utilization Method for Surface Tension Based Coal Blending Technique -Effect of Coal Fluidity-

Use of Biomass and Waste Tires to Facilitate the Use of HDPE in Coking

This work examines the role of various wastes such as pine sawdust, tire crumbs, and hydrochar from pine sawdust in reducing the deleterious impact of high-density polyethylene (HDPE) on coke contraction during coking. Contraction assessed using the Koppers-INCAR test was used as an indirect measurement of coking pressure. The Koppers-INCAR contraction of ternary blends containing coal, HDPE, and one of the other additives was tested together with their devolatilization in a thermobalance. The existence of synergism between the additives was examined to determine whether there were both positive and negative interactions between HDPE and other additives. The temperature corresponding to a 2% conversion increased with the use of additives; this was related to the degree of dangerousness of the blends. In addition, the effect of the additives on coal fluidity and coke quality was tested.

High-temperature rheological behavior and non-isothermal pyrolysis mechanism of macerals separated from different coals

It is a challenge to accurately characterize the caking behavior of coal after thermal softening and its reaction mechanism. In this work, the formation behavior of metaplast during coal macerals coking was investigated using high-temperature confocal laser scanning microscopy and high-temperature small-amplitude oscillatory shear rheometer, the source of diversities in thermal fluidity of coal was revealed by thermogravimetric-mass spectrometry analysis and kinetic-thermodynamic theory calculations. The results showed that although vitrinite was the generator of metaplast in the thermoplastic stage, the expansion rate of vitrinite from coking coal is more than 70% greater than that from gas coal for two consecutive times. Moreover, the total weight loss of vitrinite from gas coal was about 1.262 times higher than that from coking coal, but the latter exhibited more generous aliphatic groups in pyrolysis products. In the thermal flow interval, the reaction activation energy of vitrinite and inertinite from coking coal and gas coal was 271.0 ± 0.7, 302.0 ± 1.5, 241.0 ± 0.1 and 300.25 ± 1.55 kJ/mol, respectively. Eventually, the kinetic and thermodynamic mechanism parameters of raw coal and macerals had favorable correspondence regularity, and macerals with the most prominent parameters would be dominant in the overall thermal properties of raw coal.

The Important Factors of Coke Pore Formation: Collaboration and Competition between Coal Fluidity and Volatile Fraction

The Important Factors of Coke Pore Formation: Collaboration and Competition between Coal Fluidity and Volatile Fraction

ВОЛОГА ВУГІЛЛЯ (ОГЛЯД)

The article is devoted to the actual problem of the presence of excessive moisture in coal, which leads to a decrease in its operational properties. The types and properties of moisture in coal have been considered. Mathematical equations and a statistical evaluation of the effect of the maximum moisture content on the quality indicators of coals are given. The relationship between the pore volume and the maximum moisture content in coals of a various degrees of metamorphism has been analyzed. It is shown that safe humidity depends on the grade of coal and on the size class for most coal marks. The effect of moisture on the bulk density of coal concentrates and coal charges has been determined, the changes in moisture during the coal defrosting and preparation for coking have been analyzed, and the effect of moisture on the flowability of coal charges was confirmed. The moisture content in the coal charge significantly affects on the thermal regime of the coke oven battery and on the heat consumption for coking. Moisture also changes the thermal properties of the coal charge during loading: for wet material, the thermal conductivity coefficient is much higher than for the dry material and the water separately. It has been shown that the maximum moisture content depends apon the nature of coal and the degree of its metamorphism, expressed by such indicators as the yield of volatile substances, the reflection of vitrinite, the content of carbon and hydrogen, as well as the calorific capacity. With the transforming of coal from a coarse size class to a fine one, the maximum moisture capacity increases due to an increasing of the specific surface area of coal. The maximum moisture capacity practically does not depend on the coal degree of oxidation and the chemical composition of coal ash. It has been established that the bulk density reaches a maximum for dry coal and decreases to a minimum depending on the size of the pieces at a moisture content of 6-10 %. The classification of coal charges according to moisture index has been developed. An increase of the moisture content in coal leads to a decrease of its grindability and reduces the coal fluidity. An increase of the moisture content of the coal charge leads to an increase of the calorific value of coke oven gas, to the formation of coke of uneven size, to an increase of its porosity and a decrease of mechanical strength, and also leads to a decrease of the service life of coke ovens. Keywords: moisture, coal, coking, preparation scheme, coke oven gas, mathematical equations. Corresponding author D. V. Miroshnichenko, e-mail: dvmir79@gmail.com

Deciphering the Differential Influence of Organic Additives on Coal Fluidity Development: A First-Principles Investigation

Formation of high-quality coke is essentially controlled by the development of the extended stability of the coal fluid phase during industrial carbonization processes. Stabilization of coal free r...

Addition Effect of Aromatic Amines on Coal Fluidity and Coke Strength

Coal fluidity is an important parameter in coal blending techniques for coke making because it strongly influences coke qualities. On the other hand, recently, the amount of high fluidity coal has been limited. To cope with this problem, caking additive method which improves fluidity of coal has been developed and commercialized. However, since tight supply of high fluidity coal is anticipated in the future, it is of great importance to develop more effective caking additive. Therefore, in this study, we investigated effect of 11 kinds of polyaromatic hydrocarbons which include oxygen, sulfur and nitrogen containing compounds on coal fluidity in order to search for more effective chemical substances. The additives were added to low fluidity coal, and fluidity analyses were carried out according to the Gieseler plastometer method. Addition of sulfur and oxygen containing compounds lowered fluidity of coal, whereas addition of aromatic amines enhanced fluidity of coal. Coal fluidity ameliorated with increasing the molecular weight of aromatic amine, and N, N'-di-2-naphthyl-1, 4-phenylenediamine (DNPD) was the most effective aromatic amine in this study. Carbonization tests in an electric furnace were conducted to investigate an effect of DNPD on coke strength. As a result of adding only 1 wt% DNPD, fluidity of blended coal and coke strength (Drum Index) were highly improved.

Study of the swelling pressure of coals and coal charges in the coking process

The maintenance of furnaces is one of the most important problems for by-product coke production. Swelling pressure is one of the least studied factors affecting the lining of coke furnace walls. The results of studies of the swelling pressure of PJSC “Koks” feedstock coal are presented in this paper. Research has been carried out to identify the dependence of the swelling pressure on the coal quality indicators, estimated during the incoming control of the central plant laboratory of PJSC “Koks”. The plastic properties of PJSC “Koks” feedstock coals were studied using Gieseler plastometer. The relationship between the swelling pressure and the maximum coal fluidity is revealed.

PENGARUH KANDUNGAN ABU DAN ZAT TERBANG TERHADAP MAKSIMUM FLUIDITAS BATUBARA FORMASI TANJUNG DI DAERAH SEKAKO, KALIMANTAN TENGAH

ABSTRAK
 Batubara high – low volatile bituminous Formasi Tanjung di Kalimantan Tengah dikenal berpotensi sebagai coking coals. Maksimum fluiditas merupakan ssalah satu parameter penting yang sangat berkaitan dengan kualitas kokas yang dihasilkan. Penelitian ini bertujuan untuk menganalisis distribusi kandungan zat terbang dan abu serta pengaruhnya terhadap maksimum fluiditas batubara khususnya untuk batubara dari Formasi Tanjung. Batubara diambil dari lapangan di Daerah Sekako dengan channel sampling ply by ply berdasarkan litotipenya kemudian dilakukan analisis laboratorium meliputi analisis proksimat dan analisis Gieseler plastometer. Batubara yang diambil dari 2 seam Formasi Tanjung yang diproduksi tersusun dominan atas litotipe bright coals dan banded bright coals dengan memiliki kandungan abu (ash) 2,79 – 9,05 (wt%, adb), kandungan zat terbang (volatile matter) 35,14 – 39,50 (wt%, adb) dan maksimum fluiditas 22263 – 49029 (ddpm). Kandungan abu berkorelasi negatif kuat (r = -0,656; R2 = 0,431) dan tidak berpengaruh signifikan (sig. 0,055 > 0,05) terhadap maksimum fluiditas batubara. Sementara itu, kandungan zat terbang berkorelasi positif sangat kuat (r = 0,794; R2 = 0,6301) dan berpengaruh signifikan (sig. 0,003 < 0,05) terhadap maksimum fluiditas batubara. Semakin tinggi kandugan abu maka maksimum fluiditas batubara semakin rendah dan sebaliknya semakin tinggi kandungan zat terbang maka maksimum fluiditas batubara semakin tinggi. Hubungan kandungan zat terbang dengan maksimum fluiditas batubara dapat dinyatakan dengan persamaan y = 6327,9x - 200248.

Kinetic modelling of coking coal fluidity development

Coal plasticity is a phenomenon directly affecting the creation of coke structure. It is very much a time- and temperature-dependent transformation of the coal matrix, which allows changing the physical phase from solid to liquid-like and again into solid of different properties. The coking process, particularly in a plasticization temperature range, can be considered as a non-isothermal reaction at a constant heating rate. In this work, a macro-kinetics approach is applied that results in effective kinetic parameters, i.e. pre-exponential factor and activation energy. It is postulated in this work that the original content of metaplast (M0) is a part of volatile matter that melts under the effect of temperature. The coal sample can melt steadily with the temperature increase, achieving the maximum fluidity (Fmax) when the total amount of metaplast available turns into the plastic state. Coal behaviour while it is being heated can be described by two mechanisms. Under first one, the coal turns into plastic phase starting at t1 and ending at tmax, where solidification starts. This can be considered as independent reactions model. In the second model, both plasticization and solidification reactions compete over entire range of phenomena. This can be considered as reactions in the series model. The developed models were validated against experimental data of coal fluidity delivering kinetic parameters.

Perchloroethylene (PCE) adsorption on coal macerals as derived from micro-FTIR spectroscopic analysis and mapping of the C=C bonds from PCE

ABSTRACT Organic liquids are used to prepare the density medium to produce clean coal composites for coal quality and coking test evaluations during the coal exploration stage. Perchloroethylene (PCE) is commonly used as a density medium for this procedure; however, it has been shown before that PCE affects Gieseler Fluidity and Ruhr Dilatation indices of coal, as well as the quality of the resulting coke. It was also found that PCE has a negative effect on the coking properties of coals with a high inertinite content. This paper investigates the adsorption of PCE on various coal maceral surfaces using micro-Fourier Transform Infrared Spectroscopy (micro-FTIR) analysis to observe the changes in the absorbance of the double carbon bond C = C (C = C absorbance peak is used as a marker to indicate the presence of PCE) before and after PCE was applied onto their surfaces. The micro-FTIR mapping of absorbance intensity of the C = C bond on coal macerals showed an increasing trend in the presence of these bonds on the surface of all macerals with the time after exposure to the PCE. The SEM- energy-dispersive X-ray spectroscopy was used to analyze the composition of minerals associated with fusinite and semifusinite, as they were filling the pores in these macerals.

Addition Effect of Aromatic Amines on Coal Fluidity and Coke Strength

Addition Effect of Aromatic Amines on Coal Fluidity and Coke Strength

Study of chemical structure transition in the plastic layers sampled from a pilot-scale coke oven using a thermogravimetric analyzer coupled with Fourier transform infrared spectrometer

The aim of this study was to characterize the pyrolysis behavior of the plastic layer formed during the coking process in a 4 kg laboratory-scale coke oven facility. The 4 kg coke oven rig was used to produce semi-coke samples that included the plastic layer. The semi-coke samples were analyzed by using the Synchrotron Micro-CT to characterize their physical structures and identify the plastic layer features. Sectioned plastic layer samples corresponding to softening, maximum fluidity, and resolidification of coal were obtained for five coking coals of varying thermoplastic properties. Pyrolysis behavior and structural changes of the plastic layer samples were analyzed by a thermogravimetric analyzer coupled with a Fourier transform infrared spectroscopy (TG-FTIR) and an attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). The TG-FTIR analysis allowed the characterization of the changes in pyrolysis behavior including volatile matter yields, the changes in aliphatic and aromatic C–H structures in the sectioned plastic layer samples. These structure changes agreed well with the ATR-FTIR analysis which also showed chemical structure changes across the plastic layer. The results suggest that the aliphatic C–H bonds of the five coals underwent the greatest reduction with the progression of the coking process in the coal charge. It was observed that the aliphatic C–H across the thermoplastic layer region varied with the thermoplastic properties of the parent coal. This implies that the aliphatic structures in coal may have played a significant role in the development of thermoplastic properties during the formation of the plastic layer.

Evolution profile of gases during coal carbonization and relationship between their amounts and the fluidity or coke strength

The evolution of inorganic-gases (H2, CO, CO2 or H2O) and hydrocarbon gases CH4, C2(C2H4, C2H6), or C3(C3H6 + C3H8) during the carbonization of caking coals is examined to clear the influence of the evolution amount of these gases on the Gieseler maximum fluidity (MF) and coke strength (DI15015). The samples are carbonized at 3 °C/min up to 1000 °C in high-purity He. The MF and the evolution profile of gases depend on the coal type. A negative relation exists between evolution amounts of gases, except for H2, until initial softening temperature (IST) and MF values. Additionally, the evolution amounts of inorganic gases, except for H2, until the IST increase with the increase of the carboxyl (COOH) group contents in raw coal. Moreover, the MF values trends to decrease with the increase in the COOH in raw samples. Thereby, it is found that the inherently-present coal-O adverse affect coal fluidity. Drum index (DI15015) of coke increases with the increase of C%-dry ash free (daf), fixed carbon (FC) %-dry, and reflectance (R0) vol% in raw coal, while the values decrease with the increase O%-daf and volatile matter (VM) %-dry. The DI15015 values exhibit an increasing trend with regard to the amount of the evolved H2 or CH4 during the carbonization. However, the values decrease as the amount of O-containing gases increased. A similar trend is observed in semi-coke and coke, where the values decrease as the remaining O% increased. Although the proportion of turbostatic-C (T-carbon) in coke depends on the coal type, DI15015 increases as the proportion of T-carbon increased. Therefore, it is found that the coal-O also has an adverse influence on coke strength.

An index of fluidity-temperature area for evaluating cohesiveness of coking coal by Gieseler fluidity characterization

Gieseler fluidity characterization is an important method to evaluate the fluidity of coal which highly influences the cohesive properties of coke formation. A concept of fluidity-temperature area SlgF instead of maximum fluidity lgMF was put forward to be used as the index of Gieseler fluidity characterization. Thirty-five coal samples were tested by Gieseler characterization and the sensitivity for identifying coal cohesiveness by SlgF and lgMF were compared. It was found that SlgF has a more sensitive resolution of coal fluidity than lgMF and it could give a correct result for judging coal cohesiveness in accordance with the comprehensive cohesiveness in most cases, especially for coals having almost same lgMF values.

Influence of Inherently Present Oxygen-Functional Groups on Coal Fluidity and Coke Strength

The effect of various oxygen-containing compounds added and/or inherent O-species on coal fluidity and coke strength has been investigated in detail. When several O-containing compounds, which have different O-containing groups, are added independently to caking coal, the MF value almost decreases, and the extent of the decrease being ether < ketone < lactone < hydroxyl < acid anhydride < < ether/hydroxyl/lactone < carboxyl group. The COOH content in four coals used increases with decreasing C%, and the MF values decrease with increasing the content. The evolution of gaseous O-containing species (CO, CO2, and H2O) during carbonization at 3 °C/min of four coals up to 400 °C has been studied mainly with a flow-type quartz-made fixed-bed reactor to clarify the effect of the amount of O-containing gases evolved with the Gieseler fluidity of coal particles. A positive correlation is found between the amount of CO, CO2, or H2O evolved up to 400 °C and the COOH content in coal. However, a negative correlation be...

Study Relationship Between the Coal Thermoplastic Factor With Its Organic and Inorganic Properties by the Support Vector Regression Method

ABSTRACT Metallurgical cokes, as fuel for blast furnaces, have certain properties which are directly related to their blended parental coal characters. The maximum fluidity (MF) of coal as an energy index is typically used to estimate the coke properties. In this investigation, Support Vector Regression (SVR), as an intelligent method, has been applied to link characteristics and pyrolysis properties of coal samples with their representative MFs. SVR variable importance measurement (VIM) through a wide range of coal properties indicated that volatile matter (VM) and maximum vitrinite reflectance (Rmax) are the most effective parameters for the MF prediction. The results indicated that low rank coal samples (VM>45% and Rmax>0.7) have log(MF) higher than 14 and high rank ones (VM<35% and Rmax<0.6) have log(MF) less than 4. The evaluation of the SVR model trained with these two selected input variables showed that SVR can predict MF quite accurately where the coefficient of determination (R 2) between actual MF and SVR predicted was 0.86. According to these results, generation of SVR models which can predict and measure variable importance dependently, potentially may be applied for the scaling up of laboratory coal thermoplastic behavior to industrial levels, helping to sustainable development, and satisfactorily estimating coal consumption in the steel-making plants.

Thermoplastic Properties of Coal and Coal Extract

The aim of this study is to find a simple, effective, and non-destructive way to estimate the fluidity of coal. Three kinds of metallurgical coals were blended in a specific ratio for fluidity measurement by a Gieseler plastometer and coke strength by the Roga test. One of the metallurgical coals was extracted with four kinds of solvents. The solvent-extracted extracts further underwent heat treatment at different temperatures and were then added to the blended coal to examine the change of fluidity and coke strength. Both the heat-treated and untreated coal extracts were further investigated by elemental analysis, thermogravimetric analysis, solid-state 13C nuclear magnetic resonance, and X-ray diffractometry, and it was found that the heat treatment will increase the degree of graphitization. The aromatic carbon content was found to correlate significantly with the fluidity of coal, and the relationship among the ratio of aromatic carbon/aliphatic carbon, aromaticity, and fluidity was studied in this work. Finally, X-ray diffractometry is suggested to be a non-destructive method to estimate the fluidity of coal.