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N-doped activated carbons were obtained by using microalgae-sodium alginate (NaAlg) as renewable precursors due to the high nitrogen content of microalgae. One simple carbonization process with flowing N2 gas only and no any other chemical agents or gases was used to prepare the activated carbons. Texture parameters, surface morphology and chemical properties of obtained activated carbons as well...
Although coalbed methane (CBM) poses potential safety hazards in coal mines, it can also be used as a clean energy source. Optimization of the borehole length to maximize gas drainage and efficient use of human and material resources are key factors that determine the feasibility and cost of CBM production. In addition, three geo-stress zones are commonly formed in front of the working face due to...
In this paper, we intensively investigate the influence of steam on the hetero-homogeneous joint ignition of dispersed coal particle streams in both O2/N2 and O2/CO2 conditions of an optically accessible flat-flame burner. Two differently ranked coals and one bituminous char were tested for a comparison. The effects of moisture content in the raw coal, steam content or diluents (N2/CO2) in the ambience,...
To help solve flow mal-distribution and cooling capacity utilization problems in parallel cooling channels of SCRamjet, the variable channel sectional area design is put forward. 3D modelling of the flow and heat transfer in multiple parallel channels is carried out under supercritical pressure. The flow distribution reasonability and cooling effect under different channel sectional area designs are...
Thermal cracking is an important step of heavy tar processing, in which covalent bonds are initially cleaved to form free radical fragments. The free radical fragments, namely the reactive intermediates, react with each other to form lighter products and coke. Quantity and activity of these reactive radicals determine the products distribution and process operation. Since few studies can be found...
This study applied the high temperature stage microscope to investigate coal char combustion in air (O2/N2) and O2/CO2 (volume, 21%/79%) atmospheres with the effect of gasification. A reaction front combustion model was also proposed, coupled with effect of char gasification, to predict the key parameters of char combustion in the O2/CO2 atmospheres. The combustion process and particle evolution of...
The quantitative characterization of pore size distribution in low-rank coal reservoirs is significant for the determination of gas content and evaluation of coalbed methane (CBM) development potential. However, each test method can only detect the limited pore size range and the measured data cannot be used comprehensively. In this paper, a continuous distribution model of pore space was constructed...
A three dimensional transient model was developed to simulate the pyrolysis process of low-rank sub-bituminous coal in a laboratory-scale externally heated fixed-bed reactor. The water evaporation and the release of volatiles were taken into account in the model. The simulation was first validated by the central temperature evolution of reactor. The evolution of bed temperature, generation of gaseous...
Fly ash cenosphere/mullite (FACs/M) composites with excellent high-temperature resistance were prepared through a tert-butyl alcohol gelcasting process, using the mullite and FACs as the matrix and the filler, respectively, and the matrix of mullite was derived from phase transformation of the raw material of kaolin. Results show that the FACs/M exhibited low density and high specific compressive...
The modes in which Na occurs play an important role in its release and catalytic effects during thermal utilization of Zhundong coal. The modes of Na transform with increasing temperature during pyrolysis, but the transformation mechanism remains unclear. In this study, an acid-washed coal was used as a substrate to eliminate the influence of Na inherently present in the raw coal. Na2SO4, NaCl, NaHCO...
The combustion process of diesel/natural gas dual-fuel engine is complicated. In order to decouple the combustion process of natural gas (NG) and diesel, a wide range of the NG from zero to 75%, by increasing the NG flow rate at a constant air and diesel consumption rate were studied. A detailed analysis based on heat release rate data has been carried out to better understand the effect and underlying...
A high performance surfactant formulation was developed using more universally accepted Winsor type phase behavior tests rather than relying primarily on interfacial tension (IFT) measurement for the first time for Daqing oilfield. A surfactant mixture of alkylbenzene sulfonate and fatty alcohol propoxylated ether sulfate was identified which was able to form middle-phase microemulsion with Daqing...
This work investigates the effect of fuel reactivity, mixture preparation (premixed or diffusive) and equivalence ratio (φ = 0.6, 1.0) on the combustion and emission characteristics of ethanol, diesel-gasoline, n-heptane-iso-octane, n-heptane-ethanol and decane-ethanol in a constant volume bomb. It provides the direction to improve the combustion efficiency and reduce the pollutant emissions for the...
The effects of Ni promoter on Mo-S/CNT catalyst towards hydrodesulfurization (HDS) and hydrogen evolution reactions (HER) were studied. Ni promoter was introduced into Mo-S/CNT catalyst by one-step or mechanical mixing method, and Ni species presented in the form of Ni-Mo-S or Ni3S4, respectively. Catalytic assessments indicated that Ni-Mo-S structure had obviously better HDS and HER activities than...
Two-stage solvent extraction, involving acetone (light extraction) and tetrahydrofuran (heavy extraction), was used to obtain materials from the fluid component of the coal matrix during the thermoplastic stage of pyrolysis. These extracted materials were characterized using Laser desorption ionization time of flight mass spectrometry, Gas chromatography-mass spectrometer, 1H nuclear magnetic resonance...
The elliptical orifice diesel nozzle has potential beneficial for improving spray and air-fuel mixing quality, which has great impact on combustion and emission performances for diesel engine. This paper presents experimental studies on the macro spray characteristics and the mechanism of axis-switching for elliptical and circular orifice diesel nozzles with same cross section area, with biodiesel...
Sulfur-containing compounds (SCCs) are the most abundant heteroatom compounds in petroleum. The characterization of SCCs in crude oils and petroleum products has great importance not only for the downstream refining process control/optimization and environmental compliance but also for upstream geochemical studies for exploration and production. In recent years, a variety of methods to analyze SCCs...
Fuel spray and atomization characteristics play an important role in the performance of internal combustion engines and many applications of industry. In drop aerobreakup, there are two main breakup modes: general bag breakup and shear breakup, which are induced by Rayleigh-Taylor instability and Kelvin-Helmholtz instability, respectively. Influence of surfactant on drop deformation and breakup is...
BTX (benzene, toluene, and xylene) was gained from anisole by gas-phase hydrodeoxygenation (HDO) at ambient pressure with zeolite catalysts. The role of supports such as HBeta, ZSM-5, HY, and γ-Al2O3 was investigated. The effect of temperature and 1/WHSV on the product distribution was also evaluated. The results show that the content of BTX with Fe/Ni/HBeta catalysts, peaked at 24.87%. Fe/Ni/ZSM-5...
Developed fractures are beneficial for the efficient development of tight reservoir. But they also lead to formation damage induced by particle capture in fractures during drill-in fluid loss. Effective modelling of particle transport and capture behavior is critical to the prediction and prevention of formation damage. However, the behaviors of particulate suspension transport in fractured media...
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