Theoretical analysis of hydrogen solubility in direct coal liquefaction solvents

The cyclic hydrogenation technology in a direct coal liquefaction process relies on the dissolved hydrogen of the solvent or oil participating in the hydrogenation reaction.Thus,a theoretical basis for process optimization and reactor design can be established by analyzing the solubility of hydrogen in liquefaction solvents.Experimental studies of hydrogen solubility in liquefaction solvents are challenging due to harsh reaction conditions and complex solvent compositions.In this study,the composition and content of liquefied solvents were analyzed.As model compounds,hexadecane,toluene,naphthalene,tetrahydronaphthalene,and phenanthrene were chosen to represent the liquefied solvents in chain alkanes and monocyclic,bicyclic,and tricyclic aromatic hydrocarbons.The solubility of hydrogen X(mol/mol)in pure solvent components and mixed solvents(alkanes and aromatics mixed in proportion to the chain alkanes+bicyclic aromatic hydrocarbons,bicyclic saturated aromatic hydrocarbons+bicyclic aromatic hydrocarbons,and bicyclic aromatic hydrocarbons+compounds containing het-eroatoms composed of mixed components)are determined using Aspen simulation at temperature and pressure conditions of 373–523 K and 2–10 MPa.The results demonstrated that at high temperatures and pressures,the solubility of hydrogen in the solvent increases with the increase in temperature and pressure,with the pressure having a greater impact.Further-more,the results revealed that hydrogen is more soluble in straight-chain alkanes than in other solvents,and the solubility of eicosanoids reaches a maximum of 0.296.The hydrogen solubility in aromatic ring compounds decreased gradually with an increase in the aromatic ring number.The influence of chain alkanes on the solubility of hydrogen predominates in a mixture of solvents with different mixing ratios of chain alkanes and aromatic hydrocarbons.The solubility of hydrogen in mixed aromatic solvents is less than that in the corresponding single solvents.Hydrogen is less soluble in solvent compounds containing heteroatoms than in compounds without heteroatoms.

Research on the maceral characteristics of Shenhua coal and efficient and directional direct coal liquefaction technology

In this research,molecular structure models were developed respectively for Shenhua coal vitrinite concentrates(SDV)and inertinite concentrates(SDI),on the basis of information on constitutional unit of Shenhau coal and elemental analysis results obtained from^(13)C-NMR analysis characterization,FTIR analysis characterization,X-ray diffraction XRD and XPS analysis characterization.It can be observed from characterization data and molecular structure models that the structure of SDV and SDI is dominated by aromatic hydrocarbon,with aromaticity of SDI higher than that of SDV;SDV mainly consists of small molecule basic structure unit,while SDI is largely made from macromolecular structure unit.Based on bond-level parameters of the molecular model,the research found through the autoclave experiment that vitrinite liquefaction process goes under thermodynamics control and inertinite liquefaction process under dynamics control.The research developed an efficient directional direct coal liquefaction technology based on the maceral characteristics of Shenhua coal,which can effectively improve oil yield and lower gas yield.

Co-pyrolysis characteristics and interaction route between low-rank coals and Shenhua coal direct liquefaction residue

To reasonably utilize the coal direct liquefaction residue(DLR), contrasting research on the co-pyrolysis between different low-rank coals and DLR was investigated using a TGA coupled with an FT-IR spectrophotometer and a fixed-bed reactor. GC–MS, FTIR, and XRD were used to explore the reaction mechanisms of the various co-pyrolysis processes. Based on the TGA results, it was confirmed that the tetrahydrofuran insoluble fraction of DLR helped to catalyze the conversion reaction of lignite. Also, the addition of DLR improved the yield of tar in the fixed-bed, with altering the composition of the tar. Moreover, a kinetic analysis during the co-pyrolysis was conducted using a distributed activation energy model. The co-pyrolysis reactions showed an approximate double-Gaussian distribution.

The relationship between the microstructures and catalytic behaviors of iron–oxygen precursors during direct coal liquefaction

A series of both unsupported and coal‐supported iron–oxygen compounds with gradual changes in microstructure were synthesized by a precipitation‐oxidation process at 20 to 70°C.The relationship between the microstructures and catalytic activities of these precursors during direct coal liquefaction was studied.The results show that the microstructure could be controlled through adjusting the synthesis temperature during the precipitation‐oxidation procedure,and that compounds synthesized at lower temperatures exhibit higher catalytic activity.As a result of their higher proportions ofγ‐FeOOH orα‐FeOOH crystalline phases,the unsupported iron–oxygen compounds synthesized at 20–30°C,which also had high specific surface areas and moisture levels,generate oil yields 4.5%–4.6%higher than those obtained with precursors synthesized at 70°C.It was also determined that higher oil yields were obtained when the catalytically‐active phase formed by the precursors during liquefaction(pyrrhotite,Fe1-xS)had smaller crystallites.Feed coal added as a carrier was found to efficiently disperse the active precursors,which in turn significantly improved the catalytic activity during coal liquefaction.

Mechanisms and characteristics of mesocarbon microbeads prepared by co-carbonization of coal tar pitch and direct coal liquefaction residue

DCLR-P was prepared by direct coal liquefaction residue (DCLR) with ash removal.In the present experiments,mesocarbon microbeads (MCMBs) were prepared by co-carbonization of coal tar pitch (CTP) and DCLR-P.With the increase of DCLR-P content,the yield of MCMBs increased from 47.8% to 56.8%.At the same time,the particle sizes distribution of MCMBs was narrowed,resulting in the decrease of D9o/D10 ratio from 154.88 to 6.53.The results showed that DCLR-P had a positive effect on the preparation of MCMBs.1H-NMR,FTIR,SEM and XRD were used to analyze the mechanisms and characteristics of MCMBs prepared by co-carbonization of CTP and DCLR-P.The results showed that the Proton Donor Quality Index (PDQI) of DCLR-P was 13.32,significantly higher than that of CTP (0.83).This indicated that DCLR-P had more naphthenic structure than CTP,which leads to hydrogen transferring in polycondensation reaction.The aliphatic structure of DCLR-P can improve the solubility and fusibility of mesophase,thereby making the structure of MCMBs more structured.The microstructure of the graphitized MCMBs had a substantially parallel carbon layer useful for its electrical performance.The performance of graphitized MCMBs as a negative electrode material for Li-ion batteries was tested.The particle sizes,tap density,specific surface area and initial charge-discharge efficiency of graphitized MCMBs met the requirements of CMB-I in GB/T-24533-2009.However,the initial discharge capacity of graphitized MCMB was only 296.3 mA h g-1 due to the low degree of graphitization of MCMBs.

Study on reaction characteristics of phenolic hydroxyl in coal by using the model compound during direct coal liquefaction

The reaction characteristics of phenolic hydroxyl group were studied under the conditions of direct coal liquefaction. 2-naphthol was used as a coal model compound in this study. Under the conditions of with and without catalysts, a series of experiments were conducted at different temperatures, pressures and reaction time. Gas chromatography-mass spectrometry and gas chromatography were used to identify and quantify the reactants and products respectively. The conversion of 2-naphthol rises with the increase of reaction temperature, initial pressure and catalyst amount. The results indicated that tem- perature had a significant effect on 2-naphthol conversion, which promoted the dehydroxylation reaction. However, initial pressure had an important influence on the hydrogenation of 2-naphthol and naphthalene. The iron catalyst plays a significant role of cracking instead of hydrogenation. It is concluded that the harsh reaction conditions of high temperature, high pressure, and more catalyst are conducive to promoting dehydroxylation of 2-naphthol. The reaction mechanism was put forward based the experimental results, in which 2-tetralone was an intermediate.

Spatio-temporal variation and propagation direction of coal fire in Jharia Coalfield,India by satellite-based multi-temporal night-time land surface temperature imaging

In this paper,the spatio-temporal variation and propagation direction of coal fire were studied in the Jharia Coalfield(JCF),India during 2006–2015 through satellite-based night-time land surface temperature(LST)imaging.The LST was retrieved from Advanced Spaceborne Thermal Emission and Reflection Radiometer(ASTER)night-time thermal-infrared data by a robust split-window algorithm based on scene-specific regression coefficients,band-specific hybrid emissivity,and night-time atmospheric transmittance.The LST-profile-based coal fire detection algorithm was formulated through statistical analysis of the LST values along multiple transects across diverse coal fire locations in the JCF in order to compute date-specific threshold temperatures for separating thermally-anomalous and background pixels.This algorithm efficiently separates surface fire,subsurface fire,and thermally-anomalous transitional pixels.During the observation period,it was noticed that the coal fire area increased significantly,which resulted from new coal fire at many places owing to extensive opencast-mining operations.It was observed that the fire propagation occurred primarily along the dip direction of the coal seams.At places,lateral-propagation of limited spatial extent was also observed along the strike direction possibly due to spatial continuity of the coal seams along strike.Moreover,the opencast-mining activities carried out during 2009–2015 and the structurally weak planes facilitated the fire propagation.

Compatibility Evaluation between Direct Coal Liquefaction Residue and Bitumen

The compatibility between direct coal liquefaction residue(DCLR) and five kinds of pure bitumen(Shell-90,SK-90, ZSY-70, DM-70 and KLMY-50) was evaluated in this study. The rheological characteristics, glass transition temperatures(T_g), solubility parameters(SP) and SARA(saturates, aromatics, resins, and asphaltenes) fractions of DCLR,five kinds of pure bitumen and their blends(named as DCLR modified bitumen) were measured using the dynamic shear rheometer(DSR), differential scanning calorimetry(DSC), viscosity, and SARA tests, respectively. And the compatibility between DCLR and pure bitumen was characterized with three approaches, viz. the Cole-Cole plot,T_g, and the solubility parameter difference(SPD) method. Since each method has its own working mechanism, the compatibility ranking for the DCLR and five kinds of pure bitumen is slightly different according to the three approaches. However, the difference is pretty close and sometimes can be ignored. The general compatibility ranking decreases in the following order: Shell-90≈SK-90>DM-70≈ZSY-70>KLMY-50, which is affected by the asphaltenes content and the colloid index(I_c) value in the pure bitumen. Pure bitumen with lower asphaltenes content and colloid index(I_c) value has better compatibility with DCLR.

Determination of the gas compositions for direct coal liquefaction by gas chromatography

Via multi-dimensional gas chromatography, configured with parallel dual-channel, double detectors, valves switching and back flushing, rapid analysis of the gas compositions consisting of C1-C5 hydrocarbons and permanent gases, such as CO2, H2S, H2, and CO, for direct coal liquefaction has been realized. With four packed chromatographic columns, which are Hayesep-Q pre-column, Hayesep-Q column, molecular sieve 5A column and one PLOT A1203 S capillary column, the gas compositions for direct coal liquefaction are analyzed qualitatively and quantitatively by the external standard method. The determination method has such advantages as excellent separation, simple operation, rapid analysis and accurate results.

Direct-impact of sieving coal and gangue

Gangue from underground separation of coal can directly be used for filling mined out areas, saving transport capacity and reducing the amount of waste polluting the environment above the ground. We introduced a structure and operating principle of an underground direct-impact sieving device by which a separation experiment was carried out. By means of high speed conveyer belts, coal and gangue impacted the breaking board at high speeds ranging from 6 to 14 m/s. Given the differences of hardness between coal and gangue, after selective crushing, the gangue with the higher hardness was crushed less and coal with lower hardness crushed more, which could be separated by a 50 mm sieving plate. The material above the sieving plate was disposed of as gangue and the material below as coal. The results indicate that the crush ratio below the 50 mm sieving plate increases linearly with an increase in impact velocity and decays exponentially with an increase in hardness. Employing this equipment to separate coal and gangue, the hardness of coal f should be <2. This separation device provides relatively good effect in separating coal and gangue with a relatively wide difference of hardness.

Double-directional control bolt support technology and engineering application at large span Y-type intersections in deep coal mines

Under deep and complex geological conditions,severe deformation occurs at intersection points of Y-type roadways with large cross sections during engineering projects in coal mines,especially at junction arches.Based on in-situ investigations and theoretical studies,we have summarized typical forms of destruction and identified high stress and unrestricted support at both sides of junction arch as its main causes.In this study,we also presented double-directional control bolt support technology for a large Y-type span intersection,applied to deep intersection engineering in the Jiahe Coal Mine,which has proved effective.

INFLUENCE OF COAL SORT ON THE DIRECT REDUCTION OF HIGH-IRON-CONTENT RED MUD

The technology of coal-based direct reduction of high-ironcontent red mud is studied. The factors affecting this kind of direct reduction mainly are: coal sort, carbon amount, time, temperature and etc. has been investigated. It has been shown that an ide

Discharge characteristics of coal and extraction residue from direct coal liquefaction in partial fluidization silo

Gasification of extraction residue(ER) from direct coal liquefaction with pulverized coal is an efficient way for the utilization of carbonaceous wastes, which improve the overall efficiency of direct coal liquefaction technology. The discharge characteristics of ER mixing with pulverized coal is important paraments for its gasification process, which is seldom studied in the literature. In this study, the discharge characteristics of the pulverized coal(M1) as well as its mixture with ER(M2) were systematically investigated in an atmospheric pressure partial fluidization silo with different fluidization apparent velocity. It was observed that although M2 is a viscous powder with lower flowability than M1, the mass flow rate of M2 is 65% higher than M1 at the 3.7 mm·s-1apparent gas velocity. M2 exhibits the properties of Geldart A type powder, which improves the mass flow rate and stability of the discharged material. The mass flow rate of both M1 and M2 first increases and then slowly decreases with the increase of apparent gas velocity of the fluidizing air, which means the discharge process of M1 and M2 can be optimized by the apparent gas velocity.

Prediction of coal structure using particle size characteristics of coalbed methane well cuttings

Severely deformed coal seams barely deliver satisfactory gas production. This research was undertaken to develop a new method to predict the positions of deformed coals for a horizontal CBM well. Firstly, the drilling cuttings of different structure coals were collected from a coal mine and compared. In light of the varying cuttings characteristics for different structure coals, the coal structure of the horizontally drilled coal seam was predicted. And the feasibility of this prediction method was discussed. The result shows that exogenetic fractures have an important influence on the deformation of coal seams. The hardness coefficient of coal decreases with the deformation degree in the order of primary structural, cataclastic and fragmented coal. And the expanding-ratio of gas drainage holes and the average particle size of cuttings increase with the increase of the deformation degree. The particle size distribution of coal cuttings for the three types of coals is distinctive from each other. Based on the particle size distribution of cuttings from X-2 well in a coal seam, six sections of fragmented coal which are unsuitable for perforating are predicted. This method may benefit the optimization of perforation and fracturing of a horizontal CBM well in the study area.

Action rules of H_2 and CO in gas-based direct reduction of iron ore pellets

Alastraet： The gas-based direct reduction of iron ore pellets was carried out by simulating the typical gas composition in coal gasification process, Midrex and HyMII processes. The influences of gas composition and temperature on reduction were studied. Results show that the increasing of HE proportion is helpful to improve the reduction rate. However, when ~o（H2）：~o（CO）〉1.6：1, changes of HE content have little influence on it. Appropriate reduction temperature is about 950 ℃, and higher temperature （1 000 ℃） may unfavorably slow the reduction rate. From the kinetics analysis at 950 ℃, the most part of reduction course is likely controlled by interfacial chemical reaction mechanism and in the final stage controlled by a combined effect of gaseous diffusion and interfacial chemical reaction mechanisms. From the utilizations study of different reducing gases at 950 ℃, the key step in reduction course is the 3rd stage （FeO→Fe）, and the utilization of reducing gas increases with the rise of HE proportion.

The composition analysis of coal-derived light oil

The composition of coal-derived light oil (IBP-220℃) was separated into 5 fractions by atmospheric distillation and analyzed by gas chromatography/mass spec- trometry (GC/MS).The light oil was made at 0.1 t/d coal direct liquefaction bench scale unit (BSU) at China Coal Research Institute (CCRI).Six groups of organics,including acyclic hydrocarbon,alicyclic hydrocarbon,aromatics,phenols,polynuclear aromatics and heterocyclics,were found and 80 compounds were tentatively identified in total.Alicyclic hydrocarbon is the main component of the light oil compared to other groups whether in relative mass percentage or the number of compounds in group.The predominant oxy- gen-contained compound is phenols,and the nitrogen-containing compound is pyridine. No sulfur-containing compound is detected.

Analysis and Numerical Simulation for Tunnelling Through Coal Seam Assisted by Water Jet

Tunnel though coal seam is one of the most difficult tunnels since its risk of coal and gas outburst and the complex geological conditions.According to the directional cutting of water jet and the characteristic of the coal seam and rock mass,this paper presents a new method of tunnelling though coal seam assisted by water jet slotting,which can be divided into improving permeability of coal seam and directional cracking in the rock mass.The mechanism of improving permeability of coal seam was stated,and the crack criterion of rock during blasting was established based on fracture theory.Then,the evolution law of pressure wave and the crack propagation were simulated by FEM software ANSYS/LS-DYNA,the results show that the shape of the crush zone formed by stress wave is different between the normal borehole blasting and the slotted borehole blasting,and the tension is the main factor which let crack propagation.What is more,for normal borehole blasting,the tension concentration occurred along the direction of 45 degrees and let crack expand,while for slotted borehole blasting the tension concentration occurred along the direction of 0 degrees and 90 degrees,and the maximum tension along the direction of 0 degrees is larger than the maximum tension along the direction of 90 degrees,and the main crack expand along the direction of 0 degrees,which prove that the existence of the slot play a good role of orientation for directional cracking.

In-situ gas contents of a multi-section coal seam in Sydney basin for coal and gas outburst management

The gas content is crucial for evaluating coal and gas outburst potential in underground coal mining. This study focuses on investigating the in-situ coal seam gas content and gas sorption capacity in a representative coal seam with multiple sections (A1, A2, and A3) in the Sydney basin, where the CO_(2) composition exceeds 90%. The fast direct desorption method and associated devices were described in detail and employed to measure the in-situ gas components (Q_(1), Q_(2), and Q_(3)) of the coal seam. The results show that in-situ total gas content (Q_(T)) ranges from 9.48 m^(3)/t for the A2 section to 14.80 m^(3)/t for the A3 section, surpassing the Level 2 outburst threshold limit value, thereby necessitating gas drainage measures. Among the gas components, Q_(2) demonstrates the highest contribution to Q_(T), ranging between 55% and 70%. Furthermore, high-pressure isothermal gas sorption experiments were conducted on coal samples from each seam section to explore their gas sorption capacity. The Langmuir model accurately characterizes CO_(2) sorption behavior, with ft coefcients (R^(2)) greater than 0.99. Strong positive correlations are observed between in-situ gas content and Langmuir volume, as well as between residual gas content (Q_(3)) and sorption hysteresis. Notably, the A3 seam section is proved to have a higher outburst propensity due to its higher Q_(1) and Q_(2) gas contents, lower sorption hysteresis, and reduced coal toughness f value. The insights derived from the study can contribute to the development of efective gas management strategies and enhance the safety and efciency of coal mining operations.